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Capel, Blanche

Overview:

In mammals, the primary step in male sex determination is the initiation of testis development in the bipotential gonad primordium. This step depends on the Y-linked male sex-determining gene, Sry. Expression of Sry in the XY gonad, or as a transgene in an XX gonad, leads to the differentiation of Sertoli cells. Failures in Sertoli cell differentiation in the XY gonad result in sex reversal and ovary formation. In addition to Sertoli cell differentiation, we are studying the signaling pathways between Sry expression and early steps in testis organogenesis using mouse as a model system. Using genetic and cell biology approaches, we determined the origin of several key cell types of the testis. We also identified two pathways, proliferation and cell migration, that are controlled by Sry and lead to the architectural patterning of the testis. Currently we are investigating the novel hypothesis that reciprocal signals between the vasculature and Sertoli cells are involved in patterning testis cords. Testis organogenesis is an ideal model system to study the integration of vasculature during development of organ structure. In addition, we are investigating critical signals between Sertoli cells and germ cells during testis cord formation. Defects in these signals result in teratomas and gonadal blastomas, common neoplasias in young boys. Experimental approaches include the use of molecular and biochemical techniques, mutant mice, transgenics, organ culture assays, differential screens, immunocytochemistry imaging techniques, and classic mouse genetics.

Positions:

James B. Duke Professor of Cell Biology

Cell Biology
School of Medicine

Professor of Cell Biology

Cell Biology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Affiliate of the Regeneration Next Initiative

Regeneration Next Initiative
School of Medicine

Education:

Ph.D. 1989

Ph.D. — University of Pennsylvania

Grants:

Opposing Pathways in Mammalian Sex Determination

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
June 18, 2016
End Date
May 31, 2021

Genetics Training Grant

Administered By
Basic Science Departments
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
September 01, 1979
End Date
June 30, 2020

Organization and Function of Cellular Structure

Administered By
Basic Science Departments
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
July 01, 1975
End Date
June 30, 2020

Molecular Atlas of Lung Development - Data Coordinating Center

Administered By
Duke Clinical Research Institute
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
June 15, 2014
End Date
April 30, 2019

Center for Molecular & Cellular Studies of Ped Disease

Administered By
Pediatrics
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
April 11, 2003
End Date
November 30, 2017

Training Program in Developmental and Stem Cell Biology

Administered By
Basic Science Departments
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
May 01, 2001
End Date
October 31, 2017

Temporal profiling and functional analysis of temperature-dependent sex determination

Administered By
Cell Biology
AwardedBy
National Science Foundation
Role
Principal Investigator
Start Date
September 15, 2013
End Date
August 31, 2017

Role of Lamin B Receptor in Male Germ Cell Differentiation and Epigenetic Regulation

Administered By
Cell Biology
AwardedBy
Lalor Foundation, Inc.
Role
Principal Investigator
Start Date
September 01, 2016
End Date
August 12, 2017

Bioinformatics and Computational Biology Training Program

Administered By
Basic Science Departments
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
July 01, 2005
End Date
June 30, 2016

Opposing Pathways in Mammalian Sex Determination

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
January 01, 1998
End Date
May 31, 2016

The Seventh International Symposium on the Biology of Vertebrate Sex Determination

Administered By
Cell Biology
AwardedBy
March of Dimes
Role
Principal Investigator
Start Date
March 01, 2015
End Date
August 31, 2015

Regulation of Germ Cell Pluripotency Through The RNA-Binding Protein, DND1

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 01, 2010
End Date
July 31, 2014

A new cell population regulating cell fate and morphogenesis in the mouse testis

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
May 01, 2009
End Date
April 30, 2012

A Functional Assay to Test Conserved Mechanisms of Sex Determination in the Turtle, T. scripta

Administered By
Cell Biology
AwardedBy
National Science Foundation
Role
Principal Investigator
Start Date
May 01, 2009
End Date
July 31, 2011

WNT4- Mediated Signaling During Mammalian Sex Determination

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
April 01, 2007
End Date
March 31, 2010

Organ-specific Mechanisms of Vascular Development

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
June 01, 1999
End Date
October 31, 2008

Mechanisms of Gonad Organogenesis in the red-eared slider tutle (Trachemys scripta)

Administered By
Cell Biology
AwardedBy
National Science Foundation
Role
Principal Investigator
Start Date
September 01, 2003
End Date
February 29, 2008

Fourth Annual Symposium on the Biology of Vertebrate Sex Determination

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
March 10, 2006
End Date
November 30, 2006

Zeiss LSM510 META confocal-fluorescence spectroscopy

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Co Investigator
Start Date
May 01, 2003
End Date
October 30, 2004

Analysis of Sonic Hedgehog Function During Gonadogenesis

Administered By
Cell Biology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 01, 2001
End Date
July 31, 2004

Sry and Signals Controlling the Origin and Specification of Sertoli Cells

Administered By
Cell Biology
AwardedBy
National Science Foundation
Role
Principal Investigator
Start Date
August 01, 1999
End Date
July 31, 2002
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Awards:

AAAS Fellows. American Association for the Advancement of Science, The.

Type
National
Awarded By
American Association for the Advancement of Science, The
Date
January 01, 2010

Publications:

Numb regulates somatic cell lineage commitment during early gonadogenesis in mice.

During early gonadogenesis, proliferating cells in the coelomic epithelium (CE) give rise to most somatic cells in both XX and XY gonads. Previous dye-labeling experiments showed that a single CE cell could give rise to additional CE cells and to both supporting and interstitial cell lineages, implying that cells in the CE domain are multipotent progenitors, and suggesting that an asymmetric division is involved in the acquisition of gonadal cell fates. We found that NUMB is asymmetrically localized in CE cells, suggesting that it might be involved. To test this hypothesis, we conditionally deleted Numb on a Numb-like mutant background just prior to gonadogenesis. Mutant gonads showed a loss of cell polarity in the surface epithelial layers, large interior cell patches expressing the undifferentiated marker LHX9, and loss of differentiated cells in somatic cell lineages. These results indicate that NUMB is necessary for establishing polarity in CE cells, and that asymmetric divisions resulting from CE polarity are required for commitment to differentiated somatic cell fates. Surprisingly, germ cells, which do not arise from the CE, were also affected in mutants, which may be a direct or indirect effect of loss of Numb.

Authors
Lin, Y-T; Barske, L; DeFalco, T; Capel, B
MLA Citation
Lin, Y-T, Barske, L, DeFalco, T, and Capel, B. "Numb regulates somatic cell lineage commitment during early gonadogenesis in mice." March 30, 2017.
PMID
28360133
Source
epmc
Published In
Development (Cambridge)
Publish Date
2017
DOI
10.1242/dev.149203

Genome-wide identification of regulatory elements in Sertoli cells.

A current goal of molecular biology is to identify transcriptional networks that regulate cell differentiation. However, identifying functional gene regulatory elements has been challenging in the context of developing tissues where material is limited and cell types are mixed. To identify regulatory sites during sex determination, we subjected Sertoli cells from mouse fetal testes to DNaseI-seq and ChIP-seq for H3K27ac. DNaseI-seq identified putative regulatory sites around genes enriched in Sertoli and pregranulosa cells; however, active enhancers marked by H3K27ac were enriched proximal to only Sertoli-enriched genes. Sequence analysis identified putative binding sites of known and novel transcription factors likely controlling Sertoli cell differentiation. As a validation of this approach, we identified a novel Sertoli cell enhancer upstream of Wt1, and used it to drive expression of a transgenic reporter in Sertoli cells. This work furthers our understanding of the complex genetic network that underlies sex determination and identifies regions that potentially harbor non-coding mutations underlying disorders of sexual development.

Authors
Maatouk, DM; Natarajan, A; Shibata, Y; Song, L; Crawford, GE; Ohler, U; Capel, B
MLA Citation
Maatouk, DM, Natarajan, A, Shibata, Y, Song, L, Crawford, GE, Ohler, U, and Capel, B. "Genome-wide identification of regulatory elements in Sertoli cells." Development (Cambridge, England) 144.4 (February 2017): 720-730.
PMID
28087634
Source
epmc
Published In
Development (Cambridge)
Volume
144
Issue
4
Publish Date
2017
Start Page
720
End Page
730
DOI
10.1242/dev.142554

A timecourse analysis of systemic and gonadal effects of temperature on sexual development of the red-eared slider turtle Trachemys scripta elegans.

Temperature dependent sex determination (TSD) is the process by which the environmental temperature experienced during embryogenesis influences the sex of an organism, as in the red-eared slider turtle Trachemys scripta elegans. In accord with current paradigms of vertebrate sex determination, temperature is believed to exert its effects on sexual development in T. scripta entirely within the middle third of development, when the gonad is forming. However, whether temperature regulates the transcriptome in T. scripta early embryos in a manner that could influence secondary sex characteristics or establish a pro-male or pro-female environment has not been investigated. In addition, apart from a handful of candidate genes, very little is known about potential similarities between the expression cascade during TSD and the genetic cascade that drives mammalian sex determination. Here, we conducted an unbiased transcriptome-wide analysis of the effects of male- and female-promoting temperatures on the turtle embryo prior to gonad formation, and on the gonad during the temperature sensitive period. We found sexually dimorphic expression reflecting differences in steroidogenic enzymes and brain development prior to gonad formation. Within the gonad, we mapped a cascade of differential expression similar to the genetic cascade established in mammals. Using a Hidden Markov Model based clustering approach, we identified groups of genes that show heterochronic shifts between M. musculus and T. scripta. We propose a model in which multiple factors influenced by temperature accumulate during early gonadogenesis, and converge on the antagonistic regulation of aromatase to canalize sex determination near the end of the temperature sensitive window of development.

Authors
Czerwinski, M; Natarajan, A; Barske, L; Looger, LL; Capel, B
MLA Citation
Czerwinski, M, Natarajan, A, Barske, L, Looger, LL, and Capel, B. "A timecourse analysis of systemic and gonadal effects of temperature on sexual development of the red-eared slider turtle Trachemys scripta elegans." Developmental biology 420.1 (December 2016): 166-177.
PMID
27671871
Source
epmc
Published In
Developmental Biology
Volume
420
Issue
1
Publish Date
2016
Start Page
166
End Page
177
DOI
10.1016/j.ydbio.2016.09.018

A grafted ovarian fragment rescues host fertility after chemotherapy.

Can host fertility be rescued by grafting of a fragment of a healthy ovary soon after chemotherapy?We found that grafting a green fluorescent protein (GFP)-positive fragment from a healthy isogenic ovary to the left ovary of a chemo-treated host rescued function and fertility of the grafted host ovary, and resulted in the production of host-derived offspring as late as the sixth litter after chemotherapy (CTx) treatment, whereas none of the ungrafted controls produced a second litter.In women and girls undergoing chemotherapy, infertility and premature ovarian failure are frequent outcomes. There are accumulating reports of improved endocrine function after autotransplantation of an ovarian fragment, raising the possibility that the transplant is beneficial to the endogenous ovary.We first established a CTx treatment regimen that resulted in the permanent loss of fertility in 100% of female mice of the FVB inbred strain. We grafted an isogenic ovary fragment from a healthy female homozygous for a GFP transgene to the left ovary of 100 CTx-treated hosts, and compared fertility to 39 ungrafted controls in 6 months of continuous matings, using GFP to distinguish offspring derived from the graft, and those derived from the host.Immunofluoresece and western blot analysis of 39 treated ovaries during and 15 days after CTx treatment revealed elevated apoptosis, rapid loss of granulosa cells and an increased recruitment of growing follicles. Using immunofluorescence and confocal imaging, we tracked the outcome of the grafted tissue over 4 months and its effect on the adjacent and contralateral ovary of the host.Fifty-three percent of grafted females produced a second litter whereas none of the ungrafted females produced a second litter. The likelihood that this could occur by chance is very low (P < 0.0001).These results are shown only in mice, and whether or how they might apply to chemotherapy patients subjected to different CTx regimens is not yet clear.Our experiments prove that rescue of a chemo-treated ovary is possible, and establish a system to investigate the mechanism of rescue and to identify the factors responsible with the long-term goal of developing therapies for preservation of ovarian endocrine function and fertility in women undergoing chemotherapy.No large datasets were produced.Duke University Medical Center Chancellor's Discovery Grant to BC; ESJ was supported by an NRSA 5F31CA165545; SK was supported by NIH RO1 GM08033; RWT was supported by the Duke University School of Medicine Ovarian Cancer Research Fellowship; XBM was supported by CONICYT. The authors have no conflicts of interest to declare.

Authors
Batchvarov, IS; Taylor, RW; Bustamante-Marín, X; Czerwinski, M; Johnson, ES; Kornbluth, S; Capel, B
MLA Citation
Batchvarov, IS, Taylor, RW, Bustamante-Marín, X, Czerwinski, M, Johnson, ES, Kornbluth, S, and Capel, B. "A grafted ovarian fragment rescues host fertility after chemotherapy." Molecular human reproduction 22.12 (December 2016): 842-851.
PMID
27698028
Source
epmc
Published In
Molecular Human Reproduction
Volume
22
Issue
12
Publish Date
2016
Start Page
842
End Page
851

Cycling in the Cell Fate Landscape.

The causal relationship between the cell cycle and cell fate has recently been reconsidered in several developmental systems, now including sex determination. Direct links between cell cycle machinery and developmental factors demonstrate how modulating the cell cycle can have a profound influence on cellular decisions, through phenomena largely divided into phase-specific interactions seen as "priming" and "competence," or global changes in transcription or histone modifications during transitions. This integration challenges the common view of cell fate landscapes.

Authors
Bunce, C; Capel, B
MLA Citation
Bunce, C, and Capel, B. "Cycling in the Cell Fate Landscape." Current topics in developmental biology 116 (January 21, 2016): 153-165.
PMID
26970618
Source
epmc
Published In
Current topics in developmental biology
Volume
116
Publish Date
2016
Start Page
153
End Page
165
DOI
10.1016/bs.ctdb.2015.10.001

Left-Biased Spermatogenic Failure in 129/SvJ Dnd1Ter/+ Mice Correlates with Differences in Vascular Architecture, Oxygen Availability, and Metabolites.

Homozygosity for the Ter mutation in the RNA-binding protein Dead end 1 (Dnd1(Ter/Ter)) sensitizes germ cells to degeneration in all mouse strains. In 129/SvJ mice, approximately 10% of Dnd1(Ter/+) heterozygotes develop spermatogenic failure, and 95% of unilateral cases occur in the left testis. The first differences between right and left testes were detected at Postnatal Day 15 when many more spermatogonial stem cells (SSCs) were undergoing apoptosis in the left testis compared to the right. As we detected no significant left/right differences in the molecular pathway associated with body axis asymmetry or in the expression of signals known to promote proliferation, differentiation, and survival of germ cells, we investigated whether physiological differences might account for asymmetry of the degeneration phenotype. We show that left/right differences in vascular architecture are associated with a decrease in hemoglobin saturation and increased levels of HIF-1alpha in the left testis compared to the right. In Dnd1 heterozygotes, lower oxygen availability was associated with metabolic differences, including lower levels of ATP and NADH in the left testis. These experiments suggest a dependence on oxygen availability and metabolic substrates for SSC survival and suggest that Dnd1(Ter/+) SSCs may act as efficient sensors to detect subtle environmental changes that alter SSC fate.

Authors
Bustamante-Marin, XM; Cook, MS; Gooding, J; Newgard, C; Capel, B
MLA Citation
Bustamante-Marin, XM, Cook, MS, Gooding, J, Newgard, C, and Capel, B. "Left-Biased Spermatogenic Failure in 129/SvJ Dnd1Ter/+ Mice Correlates with Differences in Vascular Architecture, Oxygen Availability, and Metabolites." Biology of reproduction 93.3 (September 2015): 78-.
PMID
26224005
Source
epmc
Published In
Biology of Reproduction
Volume
93
Issue
3
Publish Date
2015
Start Page
78
DOI
10.1095/biolreprod.115.128850

Macrophages Contribute to the Spermatogonial Niche in the Adult Testis.

The testis produces sperm throughout the male reproductive lifespan by balancing self-renewal and differentiation of spermatogonial stem cells (SSCs). Part of the SSC niche is thought to lie outside the seminiferous tubules of the testis; however, specific interstitial components of the niche that regulate spermatogonial divisions and differentiation remain undefined. We identified distinct populations of testicular macrophages, one of which lies on the surface of seminiferous tubules, in close apposition to areas of tubules enriched for undifferentiated spermatogonia. These macrophages express spermatogonial proliferation- and differentiation-inducing factors, such as colony-stimulating factor 1 (CSF1) and enzymes involved in retinoic acid (RA) biosynthesis. We show that transient depletion of macrophages leads to a disruption in spermatogonial differentiation. These findings reveal an unexpected role for macrophages in the spermatogonial niche in the testis and raise the possibility that macrophages play previously unappreciated roles in stem/progenitor cell regulation in other tissues.

Authors
DeFalco, T; Potter, SJ; Williams, AV; Waller, B; Kan, MJ; Capel, B
MLA Citation
DeFalco, T, Potter, SJ, Williams, AV, Waller, B, Kan, MJ, and Capel, B. "Macrophages Contribute to the Spermatogonial Niche in the Adult Testis." Cell reports 12.7 (August 5, 2015): 1107-1119.
PMID
26257171
Source
epmc
Published In
Cell Reports
Volume
12
Issue
7
Publish Date
2015
Start Page
1107
End Page
1119
DOI
10.1016/j.celrep.2015.07.015

Cell fate commitment during mammalian sex determination.

The gonads form bilaterally as bipotential organs that can develop as testes or ovaries. All secondary sex characteristics that we associate with 'maleness' or 'femaleness' depend on whether testes or ovaries form. The fate of the gonads depends on a cell fate decision that occurs in a somatic cell referred to as the 'supporting cell lineage'. Once supporting cell progenitors commit to Sertoli (male) or granulosa (female) fate, they propagate this decision to the other cells within the organ. In this review, we will describe what is known about the bipotential state of somatic and germ cell lineages in the gonad and the transcriptional and antagonistic signaling networks that lead to commitment, propagation, and maintenance of testis or ovary fate.

Authors
Lin, Y-T; Capel, B
MLA Citation
Lin, Y-T, and Capel, B. "Cell fate commitment during mammalian sex determination." Current opinion in genetics & development 32 (June 2015): 144-152. (Review)
PMID
25841206
Source
epmc
Published In
Current Opinion in Genetics & Development
Volume
32
Publish Date
2015
Start Page
144
End Page
152
DOI
10.1016/j.gde.2015.03.003

Ovarian epithelium regeneration by Lgr5(+) cells.

Lgr5, a marker of stem cells in many organs, is found expressed in cells scattered through the ovarian epithelium that expand to repair and regenerate the damaged ovarian surface after each ovulation. Lgr5-positive stem cells in the ovary and the fimbria of the oviduct may be critical cells of origin for ovarian cancer.

Authors
Capel, B
MLA Citation
Capel, B. "Ovarian epithelium regeneration by Lgr5(+) cells." Nature cell biology 16.8 (August 2014): 743-744.
PMID
25082199
Source
epmc
Published In
Nature Cell Biology
Volume
16
Issue
8
Publish Date
2014
Start Page
743
End Page
744
DOI
10.1038/ncb3020

Yolk-sac-derived macrophages regulate fetal testis vascularization and morphogenesis.

Organogenesis of the testis is initiated when expression of Sry in pre-Sertoli cells directs the gonad toward a male-specific fate. The cells in the early bipotential gonad undergo de novo organization to form testis cords that enclose germ cells inside tubules lined by epithelial Sertoli cells. Although Sertoli cells are a driving force in the de novo formation of testis cords, recent studies in mouse showed that reorganization of the vasculature and of interstitial cells also play critical roles in testis cord morphogenesis. However, the mechanism driving reorganization of the vasculature during fetal organogenesis remained unclear. Here we demonstrate that fetal macrophages are associated with nascent gonadal and mesonephric vasculature during the initial phases of testis morphogenesis. Macrophages mediate vascular reorganization and prune errant germ cells and somatic cells after testis architecture is established. We show that gonadal macrophages are derived from primitive yolk-sac hematopoietic progenitors and exhibit hallmarks of M2 activation status, suggestive of angiogenic and tissue remodeling functions. Depletion of macrophages resulted in impaired vascular reorganization and abnormal cord formation. These findings reveal a previously unappreciated role for macrophages in testis morphogenesis and suggest that macrophages are an intermediary between neovascularization and organ architecture during fetal organogenesis.

Authors
DeFalco, T; Bhattacharya, I; Williams, AV; Sams, DM; Capel, B
MLA Citation
DeFalco, T, Bhattacharya, I, Williams, AV, Sams, DM, and Capel, B. "Yolk-sac-derived macrophages regulate fetal testis vascularization and morphogenesis." Proceedings of the National Academy of Sciences of the United States of America 111.23 (June 2014): E2384-E2393.
PMID
24912173
Source
epmc
Published In
Proceedings of the National Academy of Sciences of USA
Volume
111
Issue
23
Publish Date
2014
Start Page
E2384
End Page
E2393
DOI
10.1073/pnas.1400057111

Predetermination of sexual fate in a turtle with temperature-dependent sex determination.

Egg incubation temperature determines offspring sex in many reptilian species, including red-eared slider turtles, where embryos incubated at low temperatures during the initial stages of gonad formation develop as males, while those kept at higher temperatures develop as females. Incubation at the threshold, or pivotal, temperature (PvT) yields an even ratio of males and females. This strong susceptibility to temperature indicates that each embryo of this species is competent to develop as a male or a female. However, the mechanism that determines sexual fate at the PvT has not been identified. One possibility is that sexual fate is stochastic at the PvT, but coordinated by systemic signals within a single embryo. If this is the case, gonads explanted separately to culture should not coordinate their fate. Here we show that gonad pairs from embryos incubated at the PvT share a strong predisposition for one sex or the other when cultured in isolation, indicating that they were affected by shared genetic signals, maternally-deposited yolk hormones or other transient influences received prior to the stage of dissection. In ovo studies involving shifts from the male- or female-producing temperature to the PvT further indicate that embryos adopt a sexual differentiation trajectory many days prior to the onset of morphological differentiation into testes or ovaries and usually maintain this fate in the absence of an extreme temperature signal favoring the development of the other sex. Our findings therefore suggest that the outcome of sex determination in these reptiles is heavily influenced (i) by an inherent predisposition at the PvT and (ii) by the sexual differentiation trajectory established early in gonad development under male- or female-producing temperatures.

Authors
Mork, L; Czerwinski, M; Capel, B
MLA Citation
Mork, L, Czerwinski, M, and Capel, B. "Predetermination of sexual fate in a turtle with temperature-dependent sex determination." Dev Biol 386.1 (February 1, 2014): 264-271.
PMID
24316144
Source
pubmed
Published In
Developmental Biology
Volume
386
Issue
1
Publish Date
2014
Start Page
264
End Page
271
DOI
10.1016/j.ydbio.2013.11.026

Predetermination of sexual fate in a turtle with temperature-dependent sex determination

Egg incubation temperature determines offspring sex in many reptilian species, including red-eared slider turtles, where embryos incubated at low temperatures during the initial stages of gonad formation develop as males, while those kept at higher temperatures develop as females. Incubation at the threshold, or pivotal, temperature (PvT) yields an even ratio of males and females. This strong susceptibility to temperature indicates that each embryo of this species is competent to develop as a male or a female. However, the mechanism that determines sexual fate at the PvT has not been identified. One possibility is that sexual fate is stochastic at the PvT, but coordinated by systemic signals within a single embryo. If this is the case, gonads explanted separately to culture should not coordinate their fate. Here we show that gonad pairs from embryos incubated at the PvT share a strong predisposition for one sex or the other when cultured in isolation, indicating that they were affected by shared genetic signals, maternally-deposited yolk hormones or other transient influences received prior to the stage of dissection. In ovo studies involving shifts from the male- or female-producing temperature to the PvT further indicate that embryos adopt a sexual differentiation trajectory many days prior to the onset of morphological differentiation into testes or ovaries and usually maintain this fate in the absence of an extreme temperature signal favoring the development of the other sex. Our findings therefore suggest that the outcome of sex determination in these reptiles is heavily influenced (i) by an inherent predisposition at the PvT and (ii) by the sexual differentiation trajectory established early in gonad development under male- or female-producing temperatures. © 2013 Elsevier Inc.

Authors
Mork, L; Czerwinski, M; Capel, B
MLA Citation
Mork, L, Czerwinski, M, and Capel, B. "Predetermination of sexual fate in a turtle with temperature-dependent sex determination." Developmental Biology 386.1 (February 1, 2014): 264-271.
Source
scopus
Published In
Developmental Biology
Volume
386
Issue
1
Publish Date
2014
Start Page
264
End Page
271
DOI
10.1016/j.ydbio.2013.11.026

Development. The minimalist Y.

Authors
Capel, B
MLA Citation
Capel, B. "Development. The minimalist Y." Science 343.6166 (January 3, 2014): 32-33.
PMID
24385621
Source
pubmed
Published In
Science
Volume
343
Issue
6166
Publish Date
2014
Start Page
32
End Page
33
DOI
10.1126/science.1248486

Disruption of mitotic arrest precedes precocious differentiation and transdifferentiation of pregranulosa cells in the perinatal Wnt4 mutant ovary.

Mammalian sex determination is controlled by antagonistic pathways that are initially co-expressed in the bipotential gonad and subsequently become male- or female-specific. In XY gonads, testis development is initiated by upregulation of Sox9 by SRY in pre-Sertoli cells. Disruption of either gene leads to complete male-to-female sex reversal. Ovarian development is dependent on canonical Wnt signaling through Wnt4, Rspo1 and β-catenin. However, only a partial female-to-male sex reversal results from disruption of these ovary-promoting genes. In Wnt4 and Rspo1 mutants, there is evidence of pregranulosa cell-to-Sertoli cell transdifferentiation near birth, following a severe decline in germ cells. It is currently unclear why primary sex reversal does not occur at the sex-determining stage, but instead occurs near birth in these mutants. Here we show that Wnt4-null and Rspo1-null pregranulosa cells transition through a differentiated granulosa cell state prior to transdifferentiating towards a Sertoli cell fate. This transition is preceded by a wave of germ cell death that is closely associated with the disruption of pregranulosa cell quiescence. Our results suggest that maintenance of mitotic arrest in pregranulosa cells may preclude upregulation of Sox9 in cases where female sex-determining genes are disrupted. This may explain the lack of complete sex reversal in such mutants at the sex-determining stage.

Authors
Maatouk, DM; Mork, L; Chassot, A-A; Chaboissier, M-C; Capel, B
MLA Citation
Maatouk, DM, Mork, L, Chassot, A-A, Chaboissier, M-C, and Capel, B. "Disruption of mitotic arrest precedes precocious differentiation and transdifferentiation of pregranulosa cells in the perinatal Wnt4 mutant ovary." Dev Biol 383.2 (November 15, 2013): 295-306.
PMID
24036309
Source
pubmed
Published In
Developmental Biology
Volume
383
Issue
2
Publish Date
2013
Start Page
295
End Page
306
DOI
10.1016/j.ydbio.2013.08.026

Forward to the special issue on sex determination.

Authors
Capel, B; Tanaka, M
MLA Citation
Capel, B, and Tanaka, M. "Forward to the special issue on sex determination." Dev Dyn 242.4 (April 2013): 303-306.
PMID
23404452
Source
pubmed
Published In
Developmental Dynamics
Volume
242
Issue
4
Publish Date
2013
Start Page
303
End Page
306
DOI
10.1002/dvdy.23937

Testosterone levels influence mouse fetal Leydig cell progenitors through notch signaling.

Leydig cells are the steroidogenic lineage of the mammalian testis that produces testosterone, a key hormone required throughout male fetal and adult life for virilization and spermatogenesis. Both fetal and adult Leydig cells arise from a progenitor population in the testis interstitium but are thought to be lineage-independent of one another. Genetic evidence indicates that Notch signaling is required during fetal life to maintain a balance between differentiated Leydig cells and their progenitors, but the elusive progenitor cell type and ligands involved have not been identified. In this study, we show that the Notch pathway signals through the ligand JAG1 in perivascular interstitial cells during fetal life. In the early postnatal testis, we show that circulating levels of testosterone directly affect Notch signaling, implicating a feedback role for systemic circulating factors in the regulation of progenitor cells. Between Postnatal Days 3 and 21, as fetal Leydig cells disappear from the testis and are replaced by adult Leydig cells, the perivascular population of interstitial cells active for Notch signaling declines, consistent with distinct regulation of adult Leydig progenitors.

Authors
Defalco, T; Saraswathula, A; Briot, A; Iruela-Arispe, ML; Capel, B
MLA Citation
Defalco, T, Saraswathula, A, Briot, A, Iruela-Arispe, ML, and Capel, B. "Testosterone levels influence mouse fetal Leydig cell progenitors through notch signaling. (Published online)" Biol Reprod 88.4 (April 2013): 91-.
PMID
23467742
Source
pubmed
Published In
Biology of Reproduction
Volume
88
Issue
4
Publish Date
2013
Start Page
91
DOI
10.1095/biolreprod.112.106138

Disruption of mitotic arrest precedes precocious differentiation and transdifferentiation of pregranulosa cells in the perinatal Wnt4 mutant ovary

Mammalian sex determination is controlled by antagonistic pathways that are initially co-expressed in the bipotential gonad and subsequently become male- or female-specific. In XY gonads, testis development is initiated by upregulation of Sox9 by SRY in pre-Sertoli cells. Disruption of either gene leads to complete male-to-female sex reversal. Ovarian development is dependent on canonical Wnt signaling through Wnt4, Rspo1 and β-catenin. However, only a partial female-to-male sex reversal results from disruption of these ovary-promoting genes. In Wnt4 and Rspo1 mutants, there is evidence of pregranulosa cell-to-Sertoli cell transdifferentiation near birth, following a severe decline in germ cells. It is currently unclear why primary sex reversal does not occur at the sex-determining stage, but instead occurs near birth in these mutants. Here we show that Wnt4-null and Rspo1-null pregranulosa cells transition through a differentiated granulosa cell state prior to transdifferentiating towards a Sertoli cell fate. This transition is preceded by a wave of germ cell death that is closely associated with the disruption of pregranulosa cell quiescence. Our results suggest that maintenance of mitotic arrest in pregranulosa cells may preclude upregulation of Sox9 in cases where female sex-determining genes are disrupted. This may explain the lack of complete sex reversal in such mutants at the sex-determining stage. © 2013 Elsevier Inc.

Authors
Maatouk, DM; Mork, L; Chassot, AA; Chaboissier, MC; Capel, B
MLA Citation
Maatouk, DM, Mork, L, Chassot, AA, Chaboissier, MC, and Capel, B. "Disruption of mitotic arrest precedes precocious differentiation and transdifferentiation of pregranulosa cells in the perinatal Wnt4 mutant ovary." Developmental Biology 383.2 (2013): 295-306.
Source
scival
Published In
Developmental Biology
Volume
383
Issue
2
Publish Date
2013
Start Page
295
End Page
306
DOI
10.1016/j.ydbio.2013.08.026

Conserved action of β-catenin during female fate determination in the red-eared slider turtle

In reptiles such as the red-eared slider turtle Trachemys scripta, development of an ovary from the bipotential gonad requires a coordinated expansion of the cortical domain and regression of the medulla. While estrogen, which is necessary and sufficient for ovarian development in non-mammalian vertebrates, is thought to feminize both compartments, it remains unclear whether there is a signaling relationship between the two domains that coordinates their fates. We show that aromatase, the estrogen-synthesizing enzyme, is localized to the medulla of the differentiating turtle ovary and that differentiation of the medulla precedes and is independent of cortical expansion. Coordinated feminization of the two domains may therefore rely on an estrogenic signal from the differentiating medulla. In eutherian mammals, where estrogen is dispensable for early ovary development, the canonical Wnt signaling pathway is critical for female fate determination. Whether this function is conserved among vertebrates and how it is potentially integrated with estrogen signaling are uncertain. Using a novel in vitro turtle gonad culture system, we demonstrate that ectopic activation of the canonical Wnt signaling pathway in presumptive male gonads induced a partial sex-reversal of the medulla, but inhibition of the pathway was not sufficient to sex-reverse differentiating ovaries. These patterns are similar to those previously observed in mice. Wnt signaling appears to function downstream of estrogen, as ectopic activation of the pathway rescued female development when estrogen synthesis was inhibited. Our findings therefore suggest that the ovary-promoting effects of the Wnt signaling pathway may be functionally conserved between mammals and reptiles. © 2013 Wiley Periodicals, Inc.

Authors
Mork, L; Capel, B
MLA Citation
Mork, L, and Capel, B. "Conserved action of β-catenin during female fate determination in the red-eared slider turtle." Evolution and Development 15.2 (2013): 96-106.
PMID
25098635
Source
scival
Published In
Evolution and Development
Volume
15
Issue
2
Publish Date
2013
Start Page
96
End Page
106
DOI
10.1111/ede.12020

Constitutive activation of NOTCH1 signaling in Sertoli cells causes gonocyte exit from quiescence

Notch signaling components have long been detected in Sertoli and germ cells in the developing and mature testis. However, the role of this pathway in testis development and spermatogenesis remains unknown. Using reporter mice expressing green fluorescent protein following Notch receptor activation, we found that Notch signaling was active in Sertoli cells at various fetal, neonatal, and adult stages. Since Notch signaling specifies stem cell fate in many developing and mature organ systems, we hypothesized that maintenance and differentiation of gonocytes and/or spermatogonial stem cells would be modulated through this pathway in Sertoli cells. To this end, we generated mutant mice constitutively expressing the active, intracellular domain of NOTCH1 (NICD1) in Sertoli cells. We found that mutant Sertoli cells were morphologically normal before and after birth, but presented a number of functional changes that drastically affected gonocyte numbers and physiology. We observed aberrant exit of gonocytes from mitotic arrest, migration toward cord periphery, and premature differentiation before birth. These events, presumably unsupported by the cellular microenvironment, were followed by gonocyte apoptosis and near complete disappearance of the gonocytes by day 2 after birth. Molecular analysis demonstrated that these effects are correlated with a dysregulation of Sertoli-expressed genes that are required for germ cell maintenance, such as Cyp26b1 and Gdnf. Taken together, our results demonstrate that Notch signaling is active in Sertoli cells throughout development and that proper regulation of Notch signaling in Sertoli cells is required for the maintenance of gonocytes in an undifferentiated state during fetal development. © 2013 Elsevier Inc. All rights reserved.

Authors
Garcia, TX; DeFalco, T; Capel, B; Hofmann, M-C
MLA Citation
Garcia, TX, DeFalco, T, Capel, B, and Hofmann, M-C. "Constitutive activation of NOTCH1 signaling in Sertoli cells causes gonocyte exit from quiescence." Developmental Biology (2013).
PMID
23391689
Source
scival
Published In
Developmental Biology
Publish Date
2013
DOI
10.1016/j.ydbio.2013.01.031

The western painted turtle genome, a model for the evolution of extreme physiological adaptations in a slowly evolving lineage

Background: We describe the genome of the western painted turtle, Chrysemys picta bellii, one of the most widespread, abundant and well-studied turtles. We place the genome into a comparative evolutionary context, and focus on genomic features associated with tooth loss, immune function, longevity, sex differentiation and determination, and the species' physiological capacities to withstand extreme anoxia and tissue freezing. Results: Our phylogenetic analyses confirm that turtles are the sister group to living archosaurs, and demonstrate an extraordinarily slow rate of sequence evolution in the painted turtle. The ability of the painted turtle to withstand complete anoxia and partial freezing appears to be associated with common vertebrate gene networks, and we identify candidate genes for future functional analyses. Tooth loss shares a common pattern of pseudogenization and degradation of tooth-specific genes with birds, although the rate of accumulation of mutations is much slower in the painted turtle. Genes associated with sex differentiation generally reflect phylogeny rather than convergence in sex determination functionality. Among gene families that demonstrate exceptional expansions or show signatures of strong natural selection, immune function and musculoskeletal patterning genes are consistently overrepresented. Conclusions: Our comparative genomic analyses indicate that common vertebrate regulatory networks, some of which have analogs in human diseases, are often involved in the western painted turtle's extraordinary physiological capacities. As these regulatory pathways are analyzed at the functional level, the painted turtle may offer important insights into the management of a number of human health disorders.

Authors
Abramyan, J; Badenhorst, D; Biggar, KK; Borchert, GM; Botka, CW; Bowden, RM; Braun, EL; Bronikowski, AM; Bruneau, BG; Buck, LT; al, E
MLA Citation
Abramyan, J, Badenhorst, D, Biggar, KK, Borchert, GM, Botka, CW, Bowden, RM, Braun, EL, Bronikowski, AM, Bruneau, BG, Buck, LT, and al, E. "The western painted turtle genome, a model for the evolution of extreme physiological adaptations in a slowly evolving lineage." Genome Biology (2013): R28-.
PMID
23537068
Source
scival
Published In
Genome Biology
Publish Date
2013
Start Page
R28
DOI
10.1186/gb-2013-14-3-r28

Constitutive activation of NOTCH1 signaling in Sertoli cells causes gonocyte exit from quiescence

Notch signaling components have long been detected in Sertoli and germ cells in the developing and mature testis. However, the role of this pathway in testis development and spermatogenesis remains unknown. Using reporter mice expressing green fluorescent protein following Notch receptor activation, we found that Notch signaling was active in Sertoli cells at various fetal, neonatal, and adult stages. Since Notch signaling specifies stem cell fate in many developing and mature organ systems, we hypothesized that maintenance and differentiation of gonocytes and/or spermatogonial stem cells would be modulated through this pathway in Sertoli cells. To this end, we generated mutant mice constitutively expressing the active, intracellular domain of NOTCH1 (NICD1) in Sertoli cells. We found that mutant Sertoli cells were morphologically normal before and after birth, but presented a number of functional changes that drastically affected gonocyte numbers and physiology. We observed aberrant exit of gonocytes from mitotic arrest, migration toward cord periphery, and premature differentiation before birth. These events, presumably unsupported by the cellular microenvironment, were followed by gonocyte apoptosis and near complete disappearance of the gonocytes by day 2 after birth. Molecular analysis demonstrated that these effects are correlated with a dysregulation of Sertoli-expressed genes that are required for germ cell maintenance, such as Cyp26b1 and Gdnf. Taken together, our results demonstrate that Notch signaling is active in Sertoli cells throughout development and that proper regulation of Notch signaling in Sertoli cells is required for the maintenance of gonocytes in an undifferentiated state during fetal development. © 2013 Elsevier Inc.

Authors
Garcia, TX; DeFalco, T; Capel, B; Hofmann, MC
MLA Citation
Garcia, TX, DeFalco, T, Capel, B, and Hofmann, MC. "Constitutive activation of NOTCH1 signaling in Sertoli cells causes gonocyte exit from quiescence." Developmental Biology 377.1 (2013): 188-201.
Source
scival
Published In
Developmental Biology
Volume
377
Issue
1
Publish Date
2013
Start Page
188
End Page
201
DOI
10.1016/j.ydbio.2013.01.031

Testicular teratomas: an intersection of pluripotency, differentiation and cancer biology.

Teratomas represent a critical interface between stem cells, differentiation and tumorigenesis. These tumors are composed of cell types representing all three germ layers reflecting the pluripotent nature of their cell of origin. The study of these curious tumors became possible when Leroy Stevens identified the 129 mouse strain as a model of spontaneous testicular teratoma and later isolated a substrain carrying the Ter mutation, a potent modifier of tumor incidence. Early studies with 129 mice lead to the discovery of embryonal carcinoma (EC) cells which played a foundational role in the embryonic stem (ES) cell field and the study of pluripotency. The cells of origin of testicular teratomas are germ cells. During early development, primordial germ cells diverge from somatic differentiation and establish their pluripotent nature, maintaining or re-expressing core pluripotency genes; Oct4, Sox2 and Nanog. It is believed that a misregulation of male germ cell pluripotency plays a critical role in teratoma development. Several mouse models of teratoma development have now been identified, including a chromosome substitution strain, 129-Chr19(MOLF), conditional Dmrt1 and Pten alleles and the Ter mutation in the Dnd1 gene. However, it is still unknown what role somatic cells and/or physiology play in the sensitivity to teratoma development. These unusual tumors may hold the key to understanding how pluripotency is regulated in vivo.

Authors
Bustamante-Marín, X; Garness, JA; Capel, B
MLA Citation
Bustamante-Marín, X, Garness, JA, and Capel, B. "Testicular teratomas: an intersection of pluripotency, differentiation and cancer biology." Int J Dev Biol 57.2-4 (2013): 201-210. (Review)
PMID
23784831
Source
pubmed
Published In
International Journal of Developmental Biology
Volume
57
Issue
2-4
Publish Date
2013
Start Page
201
End Page
210
DOI
10.1387/ijdb.130136bc

Fine time course expression analysis identifies cascades of activation and repression and maps a putative regulator of mammalian sex determination.

In vertebrates, primary sex determination refers to the decision within a bipotential organ precursor to differentiate as a testis or ovary. Bifurcation of organ fate begins between embryonic day (E) 11.0-E12.0 in mice and likely involves a dynamic transcription network that is poorly understood. To elucidate the first steps of sexual fate specification, we profiled the XX and XY gonad transcriptomes at fine granularity during this period and resolved cascades of gene activation and repression. C57BL/6J (B6) XY gonads showed a consistent ~5-hour delay in the activation of most male pathway genes and repression of female pathway genes relative to 129S1/SvImJ, which likely explains the sensitivity of the B6 strain to male-to-female sex reversal. Using this fine time course data, we predicted novel regulatory genes underlying expression QTLs (eQTLs) mapped in a previous study. To test predictions, we developed an in vitro gonad primary cell assay and optimized a lentivirus-based shRNA delivery method to silence candidate genes and quantify effects on putative targets. We provide strong evidence that Lmo4 (Lim-domain only 4) is a novel regulator of sex determination upstream of SF1 (Nr5a1), Sox9, Fgf9, and Col9a3. This approach can be readily applied to identify regulatory interactions in other systems.

Authors
Munger, SC; Natarajan, A; Looger, LL; Ohler, U; Capel, B
MLA Citation
Munger, SC, Natarajan, A, Looger, LL, Ohler, U, and Capel, B. "Fine time course expression analysis identifies cascades of activation and repression and maps a putative regulator of mammalian sex determination." PLoS Genet 9.7 (2013): e1003630-.
PMID
23874228
Source
pubmed
Published In
PLoS genetics
Volume
9
Issue
7
Publish Date
2013
Start Page
e1003630
DOI
10.1371/journal.pgen.1003630

The western painted turtle genome, a model for the evolution of extreme physiological adaptations in a slowly evolving lineage

Background: We describe the genome of the western painted turtle, Chrysemys picta bellii, one of the most widespread, abundant, and well-studied turtles. We place the genome into a comparative evolutionary context, and focus on genomic features associated with tooth loss, immune function, longevity, sex differentiation and determination, and the species' physiological capacities to withstand extreme anoxia and tissue freezing.Results: Our phylogenetic analyses confirm that turtles are the sister group to living archosaurs, and demonstrate an extraordinarily slow rate of sequence evolution in the painted turtle. The ability of the painted turtle to withstand complete anoxia and partial freezing appears to be associated with common vertebrate gene networks, and we identify candidate genes for future functional analyses. Tooth loss shares a common pattern of pseudogenization and degradation of tooth-specific genes with birds, although the rate of accumulation of mutations is much slower in the painted turtle. Genes associated with sex differentiation generally reflect phylogeny rather than convergence in sex determination functionality. Among gene families that demonstrate exceptional expansions or show signatures of strong natural selection, immune function and musculoskeletal patterning genes are consistently over-represented.Conclusions: Our comparative genomic analyses indicate that common vertebrate regulatory networks, some of which have analogs in human diseases, are often involved in the western painted turtle's extraordinary physiological capacities. As these regulatory pathways are analyzed at the functional level, the painted turtle may offer important insights into the management of a number of human health disorders. © 2013 Shaffer et al.; licensee BioMed Central Ltd.

Authors
Shaffer, HB; Minx, P; Warren, DE; Shedlock, AM; Thomson, RC; Valenzuela, N; Abramyan, J; Amemiya, CT; Badenhorst, D; Biggar, KK; Borchert, GM; Botka, CW; Bowden, RM; Braun, EL; Bronikowski, AM; Bruneau, BG; Buck, LT; Capel, B; Castoe, TA; Czerwinski, M; Delehaunty, KD; Edwards, SV; Fronick, CC; Fujita, MK; Fulton, L; Graves, TA; Green, RE; Haerty, W; Hariharan, R; Hernandez, O; Hillier, LW; Holloway, AK; Janes, D; Janzen, FJ; Kandoth, C; Kong, L; Koning, APJD; Li, Y; Literman, R; McGaugh, SE et al.
MLA Citation
Shaffer, HB, Minx, P, Warren, DE, Shedlock, AM, Thomson, RC, Valenzuela, N, Abramyan, J, Amemiya, CT, Badenhorst, D, Biggar, KK, Borchert, GM, Botka, CW, Bowden, RM, Braun, EL, Bronikowski, AM, Bruneau, BG, Buck, LT, Capel, B, Castoe, TA, Czerwinski, M, Delehaunty, KD, Edwards, SV, Fronick, CC, Fujita, MK, Fulton, L, Graves, TA, Green, RE, Haerty, W, Hariharan, R, Hernandez, O, Hillier, LW, Holloway, AK, Janes, D, Janzen, FJ, Kandoth, C, Kong, L, Koning, APJD, Li, Y, Literman, R, and McGaugh, SE et al. "The western painted turtle genome, a model for the evolution of extreme physiological adaptations in a slowly evolving lineage." Genome Biology 14.3 (2013).
Source
scival
Published In
Genome Biology
Volume
14
Issue
3
Publish Date
2013
DOI
10.1186/gb-2013-14-3-r28

Testis formation in the fetal mouse: dynamic and complex de novo tubulogenesis.

Soon after Sry initiates male sex determination, cells in XY gonads undergo an unusual process of de novo cord formation that results in the organization of Sertoli cells into epithelial tubules enclosing germ cells and partitioning mesenchymal cells and vasculature to the interstitial space of the testis. Recent experiments investigating this dynamic process in four dimensions have begun to shed new light on the collective interactions of multiple cell types during morphogenesis of testis cords.

Authors
Cool, J; DeFalco, T; Capel, B
MLA Citation
Cool, J, DeFalco, T, and Capel, B. "Testis formation in the fetal mouse: dynamic and complex de novo tubulogenesis." Wiley Interdiscip Rev Dev Biol 1.6 (November 2012): 847-859. (Review)
PMID
23799626
Source
pubmed
Published In
Wiley Interdisciplinary Reviews: Developmental Biology
Volume
1
Issue
6
Publish Date
2012
Start Page
847
End Page
859
DOI
10.1002/wdev.62

Testis development requires the repression of Wnt4 by Fgf signaling.

The bipotential gonad expresses genes associated with both the male and female pathways. Adoption of the male testicular fate is associated with the repression of many female genes including Wnt4. However, the importance of repression of Wnt4 to the establishment of male development was not previously determined. Deletion of either Fgf9 or Fgfr2 in an XY gonad resulted in up-regulation of Wnt4 and male-to-female sex reversal. We investigated whether the deletion if Wnt4 could rescue sex reversal in Fgf9 and Fgfr2 mutants. XY Fgf9/Wnt4 and Fgfr2/Wnt4 double mutants developed testes with male somatic and germ cells present, suggesting that the primary role of Fgf signaling is the repression of female-promoting genes. Thus, the decision to adopt the male fate is based not only on whether male genes, such as Sox9, are expressed, but also on the active repression of female genes, such as Wnt4. Because loss of Wnt4 results in the up-regulation of Fgf9, we also tested the possibility that derepression of Fgf9 was responsible for the aspects of male development observed in XX Wnt4 mutants. However, we found that the relationship between these two signaling factors is not symmetric: loss of Fgf9 in XX Wnt4(-/-) gonads does not rescue their partial female-to-male sex-reversal.

Authors
Jameson, SA; Lin, Y-T; Capel, B
MLA Citation
Jameson, SA, Lin, Y-T, and Capel, B. "Testis development requires the repression of Wnt4 by Fgf signaling." Dev Biol 370.1 (October 1, 2012): 24-32.
PMID
22705479
Source
pubmed
Published In
Developmental Biology
Volume
370
Issue
1
Publish Date
2012
Start Page
24
End Page
32
DOI
10.1016/j.ydbio.2012.06.009

Sex and the circuitry: progress toward a systems-level understanding of vertebrate sex determination.

In vertebrates, the gonad arises as a bipotential primordium that can differentiate as a testis or ovary. Cells are initially primed to adopt either fate by balanced antagonistic signaling pathways and transcription networks. Sexual fate is determined by activating the testis or ovarian pathway and repressing the alternative pathway. A complex, dynamic transcription network underlies this process, as approximately half the genome is being transcribed during this period, and many genes are expressed in a sexually dimorphic manner. This network is highly plastic; however, multiple lines of evidence suggest that many elements of the pathway converge on the stabilization or disruption of Sox9 expression. The single gene mutational approach has led to the identification of ∼30 additional genes involved in vertebrate sex determination. However, >50% of human disorders of sexual development (DSDs) are not explained by any of these genes, suggesting many critical elements of the system await discovery. Emerging technologies and genetic resources enable the investigation of the sex determination network on a global scale in the context of a variable genetic background or environmental influences. Using these new tools we can investigate how cells establish a bipotential state that is poised to adopt either sexual fate, and how they integrate multiple signaling and transcriptional inputs to drive a cell fate decision. Elucidating the genetic architecture underlying sex determination in model systems can lead to the identification of conserved modules correlated with phenotypic outcomes, and critical pressure points in the network that predict genes involved in DSDs in humans.

Authors
Munger, SC; Capel, B
MLA Citation
Munger, SC, and Capel, B. "Sex and the circuitry: progress toward a systems-level understanding of vertebrate sex determination." Wiley Interdiscip Rev Syst Biol Med 4.4 (July 2012): 401-412.
PMID
22605638
Source
pubmed
Published In
Wiley Interdisciplinary Reviews: Systems Biology and Medicine
Volume
4
Issue
4
Publish Date
2012
Start Page
401
End Page
412
DOI
10.1002/wsbm.1172

Temporal differences in granulosa cell specification in the ovary reflect distinct follicle fates in mice.

The embryonic origins of ovarian granulosa cells have been a subject of debate for decades. By tamoxifen-induced lineage tracing of Foxl2-expressing cells, we show that descendants of the bipotential supporting cell precursors in the early gonad contribute granulosa cells to a specific population of follicles in the medulla of the ovary that begin to grow immediately after birth. These precursor cells arise from the proliferative ovarian surface epithelium and enter mitotic arrest prior to upregulating Foxl2. Granulosa cells that populate the cortical primordial follicles activated in adult life derive from the surface epithelium perinatally, and enter mitotic arrest at that stage. Ingression from the surface epithelium dropped to undetectable levels by Postnatal Day 7, when most surviving oocytes were individually encapsulated by granulosa cells. These findings add complexity to the standard model of sex determination in which the Sertoli and granulosa cells of the adult testis and ovary directly stem from the supporting cell precursors of the bipotential gonad.

Authors
Mork, L; Maatouk, DM; McMahon, JA; Guo, JJ; Zhang, P; McMahon, AP; Capel, B
MLA Citation
Mork, L, Maatouk, DM, McMahon, JA, Guo, JJ, Zhang, P, McMahon, AP, and Capel, B. "Temporal differences in granulosa cell specification in the ovary reflect distinct follicle fates in mice. (Published online)" Biol Reprod 86.2 (February 2012): 37-.
PMID
21976597
Source
pubmed
Published In
Biology of Reproduction
Volume
86
Issue
2
Publish Date
2012
Start Page
37
DOI
10.1095/biolreprod.111.095208

Mouse germ cell clusters form by aggregation as well as clonal divisions.

After their arrival in the fetal gonad, mammalian germ cells express E-cadherin and are found in large clusters, similar to germ cell cysts in Drosophila. In Drosophila, germ cells in cysts are connected by ring canals. Several molecular components of intercellular bridges in mammalian cells have been identified, including TEX14, a protein required for the stabilization of intercellular bridges, and several associated proteins that are components of the cytokinesis complex. This has led to the hypothesis that germ cell clusters in the mammalian gonad arise through incomplete cell divisions. We tested this hypothesis by generating chimeras between GFP-positive and GFP-negative mice. We show that germ cell clusters in the fetal gonad arise through aggregation as well as cell division. Intercellular bridges, however, are likely restricted to cells of the same genotype.

Authors
Mork, L; Tang, H; Batchvarov, I; Capel, B
MLA Citation
Mork, L, Tang, H, Batchvarov, I, and Capel, B. "Mouse germ cell clusters form by aggregation as well as clonal divisions." Mech Dev 128.11-12 (January 2012): 591-596.
PMID
22245112
Source
pubmed
Published In
Mechanisms of Development
Volume
128
Issue
11-12
Publish Date
2012
Start Page
591
End Page
596
DOI
10.1016/j.mod.2011.12.005

Germ cells are not required to establish the female pathway in mouse fetal gonads.

The fetal gonad is composed of a mixture of somatic cell lineages and germ cells. The fate of the gonad, male or female, is determined by a population of somatic cells that differentiate into Sertoli or granulosa cells and direct testis or ovary development. It is well established that germ cells are not required for the establishment or maintenance of Sertoli cells or testis cords in the male gonad. However, in the agametic ovary, follicles do not form suggesting that germ cells may influence granulosa cell development. Prior investigations of ovaries in which pre-meiotic germ cells were ablated during fetal life reported no histological changes during stages prior to birth. However, whether granulosa cells underwent normal molecular differentiation was not investigated. In cases where germ cell loss occurred secondary to other mutations, transdifferentiation of granulosa cells towards a Sertoli cell fate was observed, raising questions about whether germ cells play an active role in establishing or maintaining the fate of granulosa cells. We developed a group of molecular markers associated with ovarian development, and show here that the loss of pre-meiotic germ cells does not disrupt the somatic ovarian differentiation program during fetal life, or cause transdifferentiation as defined by expression of Sertoli markers. Since we do not find defects in the ovarian somatic program, the subsequent failure to form follicles at perinatal stages is likely attributable to the absence of germ cells rather than to defects in the somatic cells.

Authors
Maatouk, DM; Mork, L; Hinson, A; Kobayashi, A; McMahon, AP; Capel, B
MLA Citation
Maatouk, DM, Mork, L, Hinson, A, Kobayashi, A, McMahon, AP, and Capel, B. "Germ cells are not required to establish the female pathway in mouse fetal gonads." PLoS One 7.10 (2012): e47238-.
PMID
23091613
Source
pubmed
Published In
PloS one
Volume
7
Issue
10
Publish Date
2012
Start Page
e47238
DOI
10.1371/journal.pone.0047238

Temporal transcriptional profiling of somatic and germ cells reveals biased lineage priming of sexual fate in the fetal mouse gonad.

The divergence of distinct cell populations from multipotent progenitors is poorly understood, particularly in vivo. The gonad is an ideal place to study this process, because it originates as a bipotential primordium where multiple distinct lineages acquire sex-specific fates as the organ differentiates as a testis or an ovary. To gain a more detailed understanding of the process of gonadal differentiation at the level of the individual cell populations, we conducted microarrays on sorted cells from XX and XY mouse gonads at three time points spanning the period when the gonadal cells transition from sexually undifferentiated progenitors to their respective sex-specific fates. We analyzed supporting cells, interstitial/stromal cells, germ cells, and endothelial cells. This work identified genes specifically depleted and enriched in each lineage as it underwent sex-specific differentiation. We determined that the sexually undifferentiated germ cell and supporting cell progenitors showed lineage priming. We found that germ cell progenitors were primed with a bias toward the male fate. In contrast, supporting cells were primed with a female bias, indicative of the robust repression program involved in the commitment to XY supporting cell fate. This study provides a molecular explanation reconciling the female default and balanced models of sex determination and represents a rich resource for the field. More importantly, it yields new insights into the mechanisms by which different cell types in a single organ adopt their respective fates.

Authors
Jameson, SA; Natarajan, A; Cool, J; DeFalco, T; Maatouk, DM; Mork, L; Munger, SC; Capel, B
MLA Citation
Jameson, SA, Natarajan, A, Cool, J, DeFalco, T, Maatouk, DM, Mork, L, Munger, SC, and Capel, B. "Temporal transcriptional profiling of somatic and germ cells reveals biased lineage priming of sexual fate in the fetal mouse gonad." PLoS Genet 8.3 (2012): e1002575-.
PMID
22438826
Source
pubmed
Published In
PLoS genetics
Volume
8
Issue
3
Publish Date
2012
Start Page
e1002575
DOI
10.1371/journal.pgen.1002575

Two distinct origins for Leydig cell progenitors in the fetal testis.

During the differentiation of the mammalian embryonic testis, two compartments are defined: the testis cords and the interstitium. The testis cords give rise to the adult seminiferous tubules, whereas steroidogenic Leydig cells and other less well characterized cell types differentiate in the interstitium (the space between testis cords). Although the process of testis cord formation is essential for male development, it is not entirely understood. It has been viewed as a Sertoli-cell driven process, but growing evidence suggests that interstitial cells play an essential role during testis formation. However, little is known about the origin of the interstitium or the molecular and cellular diversity within this early stromal compartment. To better understand the process of mammalian gonad differentiation, we have undertaken an analysis of developing interstitial/stromal cells in the early mouse testis and ovary. We have discovered molecular heterogeneity in the interstitium and have characterized new markers of distinct cell types in the gonad: MAFB, C-MAF, and VCAM1. Our results show that at least two distinct progenitor lineages give rise to the interstitial/stromal compartment of the gonad: the coelomic epithelium and specialized cells along the gonad-mesonephros border. We demonstrate that both these populations give rise to interstitial precursors that can differentiate into fetal Leydig cells. Our analysis also reveals that perivascular cells migrate into the gonad from the mesonephric border along with endothelial cells and that these vessel-associated cells likely represent an interstitial precursor lineage. This study highlights the cellular diversity of the interstitial cell population and suggests that complex cell-cell interactions among cells in the interstitium are involved in testis morphogenesis.

Authors
DeFalco, T; Takahashi, S; Capel, B
MLA Citation
DeFalco, T, Takahashi, S, and Capel, B. "Two distinct origins for Leydig cell progenitors in the fetal testis." Dev Biol 352.1 (April 1, 2011): 14-26.
PMID
21255566
Source
pubmed
Published In
Developmental Biology
Volume
352
Issue
1
Publish Date
2011
Start Page
14
End Page
26
DOI
10.1016/j.ydbio.2011.01.011

Vascular-mesenchymal cross-talk through Vegf and Pdgf drives organ patterning.

The initiation of de novo testis cord organization in the fetal gonad is poorly understood. Endothelial cell migration into XY gonads initiates testis morphogenesis. However, neither the signals that regulate vascularization of the gonad nor the mechanisms through which vessels affect tissue morphogenesis are known. Here, we show that Vegf signaling is required for gonad vascularization and cord morphogenesis. We establish that interstitial cells express Vegfa and respond, by proliferation, to endothelial migration. In the absence of vasculature, four-dimensional imaging of whole organs revealed that interstitial proliferation is reduced and prevents formation of wedge-like structures that partition the gonad into cord-forming domains. Antagonizing vessel maturation also reduced proliferation. However, proliferation of mesenchymal cells was rescued by the addition of PDGF-BB. These results suggest a pathway that integrates initiation of vascular development and testis cord morphogenesis, and lead to a model in which undifferentiated mesenchyme recruits blood vessels, proliferates in response, and performs a primary function in the morphogenesis and patterning of the developing organ.

Authors
Cool, J; DeFalco, TJ; Capel, B
MLA Citation
Cool, J, DeFalco, TJ, and Capel, B. "Vascular-mesenchymal cross-talk through Vegf and Pdgf drives organ patterning." Proc Natl Acad Sci U S A 108.1 (January 4, 2011): 167-172.
PMID
21173261
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
108
Issue
1
Publish Date
2011
Start Page
167
End Page
172
DOI
10.1073/pnas.1010299108

Oestrogen shuts the door on SOX9.

Oestrogen exerts a robust yet imperfectly understood effect on sexual development in vertebrate embryos. New work by Pask and colleagues in BMC Biology indicates that it may interfere with male development by preventing nuclear localization of SOX9, a master regulator of the testis differentiation pathway. See research article http://www.biomedcentral.com/1741-7007/8/113.

Authors
Mork, L; Capel, B
MLA Citation
Mork, L, and Capel, B. "Oestrogen shuts the door on SOX9. (Published online)" BMC Biol 8 (August 31, 2010): 110-.
Website
http://hdl.handle.net/10161/4374
PMID
20828373
Source
pubmed
Published In
BMC Biology
Volume
8
Publish Date
2010
Start Page
110
DOI
10.1186/1741-7007-8-110

Estrogen represses SOX9 during sex determination in the red-eared slider turtle Trachemys scripta.

Production of male offspring in viviparous eutherian mammals requires a sex-determining mechanism resistant to maternal hormones. This constraint is relaxed in egg-laying species, which are sensitive to hormones during sex determination and often use an increase in aromatase, the estrogen-synthesizing enzyme, as a key feminizing signal. In the turtle Trachemys scripta, sex is normally determined by temperature, but estrogen treatment overrides this cue and leads exclusively to female development. We assessed whether the expression of SOX9, a central male sex-determining gene in mammals, or three other conserved transcription factors (WT1, GATA4, and LHX9) was regulated by estrogen signaling in the turtle. As in mice, all somatic cell types in the immature turtle gonad initially expressed WT1 and GATA4, whereas SOX9 was restricted to the Sertoli precursors and LHX9 to the coelomic epithelium and interstitium. After the bipotential period, SOX9 was abruptly down-regulated at the female temperature. Strikingly, embryos treated with beta-estradiol at the male temperature lost SOX9 expression more than two stages earlier than controls, though WT1, GATA4, and LHX9 were unaffected. Conversely, inhibition of estrogen synthesis and signaling prevented or delayed SOX9 down-regulation at the female temperature. These results suggest that endogenous estrogen feminizes the medulla of the bipotential turtle gonad by inhibiting SOX9 expression. This mechanism may be involved in the male-to-female sex reversal in wild populations exposed to environmental estrogens, and is consistent with results showing that the estrogen receptor represses Sox9 to block transdifferentiation of granulosa cells into Sertoli-like cells in the adult mouse ovary.

Authors
Barske, LA; Capel, B
MLA Citation
Barske, LA, and Capel, B. "Estrogen represses SOX9 during sex determination in the red-eared slider turtle Trachemys scripta." Dev Biol 341.1 (May 1, 2010): 305-314.
PMID
20153744
Source
pubmed
Published In
Developmental Biology
Volume
341
Issue
1
Publish Date
2010
Start Page
305
End Page
314
DOI
10.1016/j.ydbio.2010.02.010

Unmasking a role for sex chromosomes in gene silencing.

Several sexually dimorphic phenotypes correlate with sex-chromosome dosage rather than with phenotypic sex. New research suggests that sex chromosome dimorphism helps to regulate gene silencing.

Authors
Maatouk, DM; Capel, B
MLA Citation
Maatouk, DM, and Capel, B. "Unmasking a role for sex chromosomes in gene silencing." Genome Biol 11.9 (2010): 134-.
Website
http://hdl.handle.net/10161/4396
PMID
20875148
Source
pubmed
Published In
Genome Biology
Volume
11
Issue
9
Publish Date
2010
Start Page
134
DOI
10.1186/gb-2010-11-9-134

Sex determination: An avian sexual revolution

Authors
Barske, LA; Capel, B
MLA Citation
Barske, LA, and Capel, B. "Sex determination: An avian sexual revolution." Nature 464.7286 (2010): 171-172.
PMID
20220830
Source
scival
Published In
Nature
Volume
464
Issue
7286
Publish Date
2010
Start Page
171
End Page
172
DOI
10.1038/464171a

Shifting gears and putting on the brakes: Female germ cells transition into meiosis

Authors
Cook, MS; Capel, B
MLA Citation
Cook, MS, and Capel, B. "Shifting gears and putting on the brakes: Female germ cells transition into meiosis." Cell Cycle 9.3 (2010): 447-448.
PMID
20130453
Source
scival
Published In
Cell Cycle
Volume
9
Issue
3
Publish Date
2010
Start Page
447
End Page
448

Elucidation of the transcription network governing mammalian sex determination by exploiting strain-specific susceptibility to sex reversal.

Despite the identification of some key genes that regulate sex determination, most cases of disorders of sexual development remain unexplained. Evidence suggests that the sexual fate decision in the developing gonad depends on a complex network of interacting factors that converge on a critical threshold. To elucidate the transcriptional network underlying sex determination, we took the first expression quantitative trait loci (eQTL) approach in a developing organ. We identified reproducible differences in the transcriptome of the embryonic day 11.5 (E11.5) XY gonad between C57BL/6J (B6) and 129S1/SvImJ (129S1), indicating that the reported sensitivity of B6 to sex reversal is consistent with a higher expression of a female-like transcriptome in B6. Gene expression is highly variable in F2 XY gonads from B6 and 129S1 intercrosses, yet strong correlations emerged. We estimated the F2 coexpression network and predicted roles for genes of unknown function based on their connectivity and position within the network. A genetic analysis of the F2 population detected autosomal regions that control the expression of many sex-related genes, including Sry (sex-determining region of the Y chromosome) and Sox9 (Sry-box containing gene 9), the key regulators of male sex determination. Our results reveal the complex transcription architecture underlying sex determination, and provide a mechanism by which individuals may be sensitized for sex reversal.

Authors
Munger, SC; Aylor, DL; Syed, HA; Magwene, PM; Threadgill, DW; Capel, B
MLA Citation
Munger, SC, Aylor, DL, Syed, HA, Magwene, PM, Threadgill, DW, and Capel, B. "Elucidation of the transcription network governing mammalian sex determination by exploiting strain-specific susceptibility to sex reversal." Genes Dev 23.21 (November 1, 2009): 2521-2536.
PMID
19884258
Source
pubmed
Published In
Genes & development
Volume
23
Issue
21
Publish Date
2009
Start Page
2521
End Page
2536
DOI
10.1101/gad.1835809

BAX-mediated cell death affects early germ cell loss and incidence of testicular teratomas in Dnd1(Ter/Ter) mice.

A homozygous nonsense mutation (Ter) in murine Dnd1 (Dnd1(Ter/Ter)) results in a significant early loss of primordial germ cells (PGCs) prior to colonization of the gonad in both sexes and all genetic backgrounds tested. The same mutation also leads to testicular teratomas only on the 129Sv/J background. Male mutants on other genetic backgrounds ultimately lose all PGCs with no incidence of teratoma formation. It is not clear how these PGCs are lost or what factors directly control the strain-specific phenotype variation. To determine the mechanism underlying early PGC loss we crossed Dnd1(Ter/Ter) embryos to a Bax-null background and found that germ cells were partially rescued. Surprisingly, on a mixed genetic background, rescued male germ cells also generated fully developed teratomas at a high rate. Double-mutant females on a mixed background did not develop teratomas, but were fertile and produced viable off-spring. However, when Dnd1(Ter/Ter) XX germ cells developed in a testicular environment they gave rise to the same neoplastic clusters as mutant XY germ cells in a testis. We conclude that BAX-mediated apoptosis plays a role in early germ cell loss and protects from testicular teratoma formation on a mixed genetic background.

Authors
Cook, MS; Coveney, D; Batchvarov, I; Nadeau, JH; Capel, B
MLA Citation
Cook, MS, Coveney, D, Batchvarov, I, Nadeau, JH, and Capel, B. "BAX-mediated cell death affects early germ cell loss and incidence of testicular teratomas in Dnd1(Ter/Ter) mice." Dev Biol 328.2 (April 15, 2009): 377-383.
PMID
19389346
Source
pubmed
Published In
Developmental Biology
Volume
328
Issue
2
Publish Date
2009
Start Page
377
End Page
383
DOI
10.1016/j.ydbio.2009.01.041

Gonad morphogenesis in vertebrates: divergent means to a convergent end.

A critical element of successful sexual reproduction is the generation of sexually dimorphic adult reproductive organs, the testis and ovary, which produce functional gametes. Examination of different vertebrate species shows that the adult gonad is remarkably similar in its morphology across different phylogenetic classes. Surprisingly, however, the cellular and molecular programs employed to create similar organs are not evolutionarily conserved. We highlight the mechanisms used by different vertebrate model systems to generate the somatic architecture necessary to support gametogenesis. In addition, we examine the different vertebrate patterns of germ cell migration from their site of origin to colonize the gonad and highlight their roles in sex-specific morphogenesis. We also discuss the plasticity of the adult gonad and consider how different genetic and environmental conditions can induce transitions between testis and ovary morphology.

Authors
DeFalco, T; Capel, B
MLA Citation
DeFalco, T, and Capel, B. "Gonad morphogenesis in vertebrates: divergent means to a convergent end." Annual review of cell and developmental biology 25 (January 2009): 457-482. (Review)
PMID
19807280
Source
epmc
Published In
Annual Review of Cell and Developmental Biology
Volume
25
Publish Date
2009
Start Page
457
End Page
482
DOI
10.1146/annurev.cellbio.042308.13350

Mixed signals: development of the testis.

Induction and patterning of the testis occurs over a brief window of time. Before male-specific morphogenesis, the gonad primordium is bipotential and capable of developing into either an ovary or testis. However, expression of the transcription factor SRY initiates male development and induces patterning, proliferation, and epithelialization specific to the testis. Male sex determination begins with commitment of Sertoli cells via autonomous and nonautonomous mechanisms. These mechanisms have recently been shown to both promote the male fate and simultaneously repress ovarian development. A second critical event in the development of the testis is the epithelialization of testis cords. After their specification, Sertoli cells epithelialize and surround the male germ line to form large looping structures bound by extracellular matrix. Cells excluded from cord structures are called interstitial cells and comprise several different cell types, including steroidogenic cells, endothelial cells, and a smooth muscle cell that directly surround the cords. Numerous male-specific signaling pathways influence testis cord morphogenesis and specification of distinct cell types, although a coherent progression of events is unclear. In this article we focus on signals in the male gonad that first are responsible for the specification of Sertoli cells, and second for the specification and patterning of interstitial cells.

Authors
Cool, J; Capel, B
MLA Citation
Cool, J, and Capel, B. "Mixed signals: development of the testis." Semin Reprod Med 27.1 (January 2009): 5-13. (Review)
PMID
19197800
Source
pubmed
Published In
Seminars in Reproductive Medicine
Volume
27
Issue
1
Publish Date
2009
Start Page
5
End Page
13
DOI
10.1055/s-0028-1108005

The DM domain protein DMRT1 is a dose-sensitive regulator of fetal germ cell proliferation and pluripotency

Dmrt1 (doublesex and mab-3 related transcription factor 1) is a conserved transcriptional regulator of male differentiation required for testicular development in vertebrates. Here, we show that in mice of the 129Sv strain, loss of Dmrt1 causes a high incidence of teratomas, whereas these tumors do not form in Dmrt1 mutant C57BL/6J mice. Conditional gene targeting indicates that Dmrt1 is required in fetal germ cells but not in Sertoli cells to prevent teratoma formation. Mutant 129Sv germ cells undergo apparently normal differentiation up to embryonic day 13.5 (E13.5), but some cells fail to arrest mitosis and ectopically express pluripotency markers. Expression analysis and chromatin immunoprecipitation identified DMRT1 target genes, whose missexpression may underlie teratoma formation. DMRT1 indirectly activates the GDNF coreceptor Ret, and it directly represses the pluripotency regulator Sox2. Analysis of human germ cell tumors reveals similar gene expression changes correlated to DMRT1 levels. Dmrt1 behaves genetically as a dose-sensitive tumor suppressor gene in 129Sv mice, and natural variation in Dmrt1 activity can confer teratoma susceptibility. This work reveals a genetic link between testicular dysgenesis, pluripotency regulation, and teratoma susceptibility that is highly sensitive to genetic background and to gene dosage.

Authors
Krentz, AD; Murphy, MW; Kim, S; Cook, MS; Capel, B; Zhu, R; Matin, A; Sarver, AL; Parker, KL; Griswold, MD; Looijenga, LHJ; Bardwell, VJ; Zarkower, D
MLA Citation
Krentz, AD, Murphy, MW, Kim, S, Cook, MS, Capel, B, Zhu, R, Matin, A, Sarver, AL, Parker, KL, Griswold, MD, Looijenga, LHJ, Bardwell, VJ, and Zarkower, D. "The DM domain protein DMRT1 is a dose-sensitive regulator of fetal germ cell proliferation and pluripotency." Proceedings of the National Academy of Sciences of the United States of America 106.52 (2009): 22323-22328.
PMID
20007774
Source
scival
Published In
Proceedings of the National Academy of Sciences of USA
Volume
106
Issue
52
Publish Date
2009
Start Page
22323
End Page
22328
DOI
10.1073/pnas.0905431106

Choosing Sex

Authors
Capel, B
MLA Citation
Capel, B. "Choosing Sex." Scientist 23.10 (2009).
Source
scival
Published In
Scientist (Philadelphia, Pa.)
Volume
23
Issue
10
Publish Date
2009

Blurring the edges in vertebrate sex determination.

Sex in vertebrates is determined by genetically or environmentally based signals. These signals initiate molecular cascades and cell-cell interactions within the gonad that lead to the adoption of the male or female fate. Previously, genetically and environmentally based mechanisms were thought to be distinct, but this idea is fading as a result of the unexpected discovery of coincident genetic and thermal influences within single species. Together with accumulating phylogenetic evidence of frequent transitions between sex-determining mechanisms, these findings suggest that genetic and environmental sex determination actually represent points on a continuum rather than discrete categories, and that populations may shift in one direction or the other in response to mutations or changing ecological conditions. Elucidation of the underlying molecular basis of sex determination in mice has yielded a bistable model of mutually antagonistic signaling pathways and feedback regulatory loops. This system would be highly responsive to changes in the upstream primary signal and may provide a basis for the rapid evolution of and transitions between different methods of sex determination.

Authors
Barske, LA; Capel, B
MLA Citation
Barske, LA, and Capel, B. "Blurring the edges in vertebrate sex determination." Curr Opin Genet Dev 18.6 (December 2008): 499-505.
PMID
19152784
Source
pubmed
Published In
Current Opinion in Genetics and Development
Volume
18
Issue
6
Publish Date
2008
Start Page
499
End Page
505
DOI
10.1016/j.gde.2008.11.004

Sex chromatin staining in amnion cells.

INTRODUCTIONThe procedure described here provides a quick and reliable method for determining the sex of mouse embryos that are <12.5 days post-coitum (dpc). Cells from amniotic membranes are stained with toluidine blue. The presence of a heavily stained condensed chromatin body (i.e., a Barr body) indicates the XX samples. With experience, we find a >95% concordance with genotyping data based on PCR for Y-chromosome sequences in extracted tail DNA. This protocol has the advantage of speed and efficiency: When assembling cultures with live tissue, samples can be sexed in 30 min.

Authors
Capel, B; Batchvarov, J
MLA Citation
Capel, B, and Batchvarov, J. "Sex chromatin staining in amnion cells. (Published online)" CSH Protoc 2008 (November 1, 2008): pdb.prot5079-.
PMID
21356720
Source
pubmed
Published In
CSH Protoc
Volume
2008
Publish Date
2008
Start Page
pdb.prot5079

Preparing recombinant gonad organ cultures.

INTRODUCTIONIt can be useful to assay migration between any two adjacent tissues during development. This protocol assays cell migration between the gonad and mesonephros using tissue recombination between genetically marked and unmarked tissue, combined with an organ culture technique. First, agar blocks are prepared in a custom-built mold. The size and shape of the wells are important to maintain the authentic three-dimensional morphology of the organ; the molds here are designed specifically to accommodate the gonad/mesonephros complex. Freshly dissected organs are then transferred to grooves within the agar blocks, where they are allowed to grow over 24-48 h. Using this protocol, organs develop with good morphology, and show only an ~12-h delay relative to in vivo development.

Authors
Capel, B; Batchvarov, J
MLA Citation
Capel, B, and Batchvarov, J. "Preparing recombinant gonad organ cultures. (Published online)" CSH Protoc 2008 (November 1, 2008): pdb.prot5078-.
PMID
21356719
Source
pubmed
Published In
CSH Protoc
Volume
2008
Publish Date
2008
Start Page
pdb.prot5078

Notch signaling maintains Leydig progenitor cells in the mouse testis.

During testis development, fetal Leydig cells increase their population from a pool of progenitor cells rather than from proliferation of a differentiated cell population. However, the mechanism that regulates Leydig stem cell self-renewal and differentiation is unknown. Here, we show that blocking Notch signaling, by inhibiting gamma-secretase activity or deleting the downstream target gene Hairy/Enhancer-of-split 1, results in an increase in Leydig cells in the testis. By contrast, constitutively active Notch signaling in gonadal somatic progenitor cells causes a dramatic Leydig cell loss, associated with an increase in undifferentiated mesenchymal cells. These results indicate that active Notch signaling restricts fetal Leydig cell differentiation by promoting a progenitor cell fate. Germ cell loss and abnormal testis cord formation were observed in both gain- and loss-of-function gonads, suggesting that regulation of the Leydig/interstitial cell population is important for male germ cell survival and testis cord formation.

Authors
Tang, H; Brennan, J; Karl, J; Hamada, Y; Raetzman, L; Capel, B
MLA Citation
Tang, H, Brennan, J, Karl, J, Hamada, Y, Raetzman, L, and Capel, B. "Notch signaling maintains Leydig progenitor cells in the mouse testis." Development 135.22 (November 2008): 3745-3753.
PMID
18927153
Source
pubmed
Published In
Development (Cambridge)
Volume
135
Issue
22
Publish Date
2008
Start Page
3745
End Page
3753
DOI
10.1242/dev.024786

Stabilization of beta-catenin in XY gonads causes male-to-female sex-reversal.

During mammalian sex determination, expression of the Y-linked gene Sry shifts the bipotential gonad toward a testicular fate by upregulating a feed-forward loop between FGF9 and SOX9 to establish SOX9 expression in somatic cells. We previously proposed that these signals are mutually antagonistic with counteracting signals in XX gonads and that a shift in the balance of these factors leads to either male or female development. Evidence in mice and humans suggests that the male pathway is opposed by the expression of two signals, WNT4 and R-SPONDIN-1 (RSPO1), that promote the ovarian fate and block testis development. Both of these ligands can activate the canonical Wnt signaling pathway. Duplication of the distal portion of chromosome 1p, which includes both WNT4 and RSPO1, overrides the male program and causes male-to-female sex reversal in XY patients. To determine whether activation of beta-catenin is sufficient to block the testis pathway, we have ectopically expressed a stabilized form of beta-catenin in the somatic cells of XY gonads. Our results show that activation of beta-catenin in otherwise normal XY mice effectively disrupts the male program and results in male-to-female sex-reversal. The identification of beta-catenin as a key pro-ovarian and anti-testis signaling molecule will further our understanding of the mechanisms controlling sex determination and the molecular mechanisms that lead to sex-reversal.

Authors
Maatouk, DM; DiNapoli, L; Alvers, A; Parker, KL; Taketo, MM; Capel, B
MLA Citation
Maatouk, DM, DiNapoli, L, Alvers, A, Parker, KL, Taketo, MM, and Capel, B. "Stabilization of beta-catenin in XY gonads causes male-to-female sex-reversal." Hum Mol Genet 17.19 (October 1, 2008): 2949-2955.
PMID
18617533
Source
pubmed
Published In
Human Molecular Genetics
Volume
17
Issue
19
Publish Date
2008
Start Page
2949
End Page
2955
DOI
10.1093/hmg/ddn193

Expression and functional analysis of Gm114, a putative mammalian ortholog of Drosophila bam.

In the testis, the continuous production of sperm is maintained by a small population of stem cells called germ line stem cells (GSCs) in Drosophila, or spermatogonial stem cells (SSCs) in mammals. This stem cell population can self-renew or produce daughter cells that differentiate into mature sperm. In Drosophila, BMP signals inhibit GSC differentiation by blocking transcription of the gene bag of marbles (bam). Once bam is activated, germ cells initiate differentiation. We identified a novel gene in mouse, Gm114, that shows homology to Drosophila bam. In male germ cells, expression of Gm114 begins at 12.5-13.5 days post coitum (dpc), the stage in mice when germ cells cease proliferation and begin differentiation into prospermatogonia. In the adult testis, Gm114 is highly expressed in differentiated spermatocytes and spermatids but not in undifferentiated spermatogonia, strongly suggesting that, similar to Bam, GM114 plays an important role in mammalian germ line stem cell self-renewal and differentiation. Interestingly, deletion of the majority of the GM114 protein does not affect mouse viability or fertility. This suggests that either there is a function for the remaining N-terminal of GM114, or that there are alternative mechanisms in the mammalian system that control germ cell differentiation.

Authors
Tang, H; Ross, A; Capel, B
MLA Citation
Tang, H, Ross, A, and Capel, B. "Expression and functional analysis of Gm114, a putative mammalian ortholog of Drosophila bam." Dev Biol 318.1 (June 1, 2008): 73-81.
PMID
18423593
Source
pubmed
Published In
Developmental Biology
Volume
318
Issue
1
Publish Date
2008
Start Page
73
End Page
81
DOI
10.1016/j.ydbio.2008.03.001

Four-dimensional analysis of vascularization during primary development of an organ, the gonad.

Time-lapse microscopy has advanced our understanding of yolk sac and early embryonic vascularization. However, it has been difficult to assess endothelial interactions during epithelial morphogenesis of internal organs. To address this issue we have developed the first time-lapse system to study vascularization of a mammalian organ in four dimensions. We show that vascularization of XX and XY gonads is a highly dynamic, sexually dimorphic process. The XX gonad recruits vasculature by a typical angiogenic process. In contrast, the XY gonad recruits and patterns vasculature by a novel remodeling mechanism beginning with breakdown of an existing mesonephric vessel. Subsequently, in XY organs individual endothelial cells migrate and reaggregate in the coelomic domain to form the major testicular artery. Migrating endothelial cells respect domain boundaries well before they are morphologically evident, subdividing the gonad into 10 avascular regions where testis cords form. This model of vascular development in an internal organ has a direct impact on the current dogma of vascular integration during organ development and presents important parallels with mechanisms of tumor vascularization.

Authors
Coveney, D; Cool, J; Oliver, T; Capel, B
MLA Citation
Coveney, D, Cool, J, Oliver, T, and Capel, B. "Four-dimensional analysis of vascularization during primary development of an organ, the gonad." Proc Natl Acad Sci U S A 105.20 (May 20, 2008): 7212-7217.
PMID
18480267
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
105
Issue
20
Publish Date
2008
Start Page
7212
End Page
7217
DOI
10.1073/pnas.0707674105

SRY and the standoff in sex determination.

SRY was identified as the mammalian sex-determining gene more than 15 yr ago and has been extensively studied since. Although many of the pathways regulating sexual differentiation have been elucidated, direct downstream targets of SRY are still unclear, making a top down approach difficult. However, recent work has demonstrated that the fate of the gonad is actively contested by both male-promoting and female-promoting signals. Sox9 and Fgf9 push gonads towards testis differentiation. These two genes are opposed by Wnt4, and possibly RSPO1, which push gonads toward ovary differentiation. In this review, we will discuss the history of the field, current findings, and exciting new directions in vertebrate sex determination.

Authors
DiNapoli, L; Capel, B
MLA Citation
DiNapoli, L, and Capel, B. "SRY and the standoff in sex determination." Mol Endocrinol 22.1 (January 2008): 1-9. (Review)
PMID
17666585
Source
pubmed
Published In
Molecular endocrinology (Baltimore, Md.)
Volume
22
Issue
1
Publish Date
2008
Start Page
1
End Page
9
DOI
10.1210/me.2007-0250

Erratum to "A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation" [Gene Expression Patterns 7 (2007) 82-92]

Authors
Coveney, D; Ross, AJ; Slone, JD; Capel, B
MLA Citation
Coveney, D, Ross, AJ, Slone, JD, and Capel, B. "Erratum to "A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation" [Gene Expression Patterns 7 (2007) 82-92]." Gene Expression Patterns 8.7-8 (2008): 528--.
Source
scival
Published In
Gene Expression Patterns
Volume
8
Issue
7-8
Publish Date
2008
Start Page
528-
DOI
10.1016/j.gep.2008.05.005

Peritubular myoid cells are not the migrating population required for testis cord formation in the XY gonad.

Cell migration is one of the earliest events required for development of the testis. Migration occurs only in XY gonads downstream of Sry expression and is required for the subsequent epithelialization of testis cords. Using organ culture experiments and tissue recombination, we and others speculated that peritubular myoid (PTM) cells were among the migratory cells and were likely the cell type required for cord formation. However, because no unique marker was found for PTM cells, their positive identification during or after migration remained unclear. alpha-Smooth Muscle Actin (alphaSma; approved gene symbol Acta2), a classic marker of adult PTM cells,is expressed broadly in testis interstitial cells at E12.5, and becomes highly enriched in PTM cells by E15.5-16.5. We used a novel transgenic line expressingEYFP under the control of an alphaSma promoter to determine whether alphaSma-EYFP positive cellsmigrate into the gonad. Surprisingly, mesonephroi expressing alphaSma-EYFP do not contribute any EYFP positive cells to XY gonads when used as donors in recombination cultures. These results indicate that alphaSma-EYFP cells do not migrate into the gonad during the critical window of sex determination and cannot be the migrating cell type required for testis cord formation. Our results suggest that PTM cells, and most other interstitial lineages, with the exception of endothelial cells, are induced within the gonad. These experiments suggest that endothelial cells are the migrating cell type required for epithelialization of testis cords.

Authors
Cool, J; Carmona, FD; Szucsik, JC; Capel, B
MLA Citation
Cool, J, Carmona, FD, Szucsik, JC, and Capel, B. "Peritubular myoid cells are not the migrating population required for testis cord formation in the XY gonad." Sex Dev 2.3 (2008): 128-133.
PMID
18769072
Source
pubmed
Published In
Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation
Volume
2
Issue
3
Publish Date
2008
Start Page
128
End Page
133
DOI
10.1159/000143430

A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation (DOI:10.1016/j.modgep.2006.05.012)

One of the earliest morphological changes during testicular differentiation is the establishment of an XY specific vasculature. The testis vascular system is derived from mesonephric endothelial cells that migrate into the gonad. In the XX gonad, mesonephric cell migration and testis vascular development are inhibited by WNT4 signaling. In Wnt4 mutant XX gonads, endothelial cells migrate from the mesonephros and form a male-like coelomic vessel. Interestingly, this process occurs in the absence of other obvious features of testis differentiation, suggesting that Wnt4 specifically inhibits XY vascular development. Consequently, the XX Wnt4 mutant mice presented an opportunity to focus a gene expression screen on the processes of mesonephric cell migration and testicular vascular development. We compared differences in gene expression between XY Wnt4+/+ and XX Wnt4+/+ gonads and between XX Wnt4-/- and XX Wnt4+/+ gonads to identify sets of genes similarly upregulated in wildtype XY gonads and XX mutant gonads or upregulated in XX gonads as compared to XY gonads and XX mutant gonads. We show that several genes identified in the first set are expressed in vascular domains, and have predicted functions related to cell migration or vascular development. However, the expression patterns and known functions of other genes are not consistent with roles in these processes. This screen has identified candidates for regulation of sex specific vascular development, and has implicated a role for WNT4 signaling in the development of Sertoli and germ cell lineages not immediately obvious from previous phenotypic analyses.

Authors
Coveney, D; Ross, AJ; Slone, JD; Capel, B
MLA Citation
Coveney, D, Ross, AJ, Slone, JD, and Capel, B. "A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation (DOI:10.1016/j.modgep.2006.05.012)." Gene Expression Patterns 8.7-8 (2008): 529-537.
Source
scival
Published In
Gene Expression Patterns
Volume
8
Issue
7-8
Publish Date
2008
Start Page
529
End Page
537
DOI
10.1016/j.gep.2008.05.006

Sexual development of the soma in the mouse.

Sex determination in mammals results in two discrete sexes, male and female. The sexes are genetically distinct at fertilization (XY = male and XX = female). However, there is little evidence for differences in their development until mid-gestation when the gonadal primordium forms. Recent research suggests that signals within this tissue maintain the gonad in a bipotential state, balanced between two alternative fates, testis or ovary. At mid-gestation, expression of the Y-linked gene Sry in gonadal cells triggers the divergence of gonad development toward the testis pathway. The critical role of Sry may be simply to promote the stable expression of SOX9 in the key cell population in the gonad. Establishment of SOX9 in this lineage is opposed by female promoting factors that push the gonad toward an ovarian fate. Both the male and female sides of these antagonistic pathways are augmented by feedback loops and reinforcing signals that canalize development, once the initial choice is made. Hormones and growth factors produced by the developing testis regulate the male differentiation of the sex ducts and the external genitalia during fetal life. In contrast, the ovary is not required for the fetal development of female genital ducts or female external genitalia, as these organs develop in the absence of a gonad. At puberty, hormones produced by the testis or the ovary control the sex-specific differentiation of the musculature, mammary tissue, and body hair. Male or female development of the brain was previously thought to depend on hormones produced by the testis or ovary. However, recent evidence reveals expression differences between XX and XY brains prior to the time that hormones are circulating, suggesting that some influences on brain development may be autonomous to the cells of the brain.

Authors
Maatouk, DM; Capel, B
MLA Citation
Maatouk, DM, and Capel, B. "Sexual development of the soma in the mouse." Curr Top Dev Biol 83 (2008): 151-183.
PMID
19118666
Source
pubmed
Published In
Current topics in developmental biology
Volume
83
Publish Date
2008
Start Page
151
End Page
183
DOI
10.1016/S0070-2153(08)00405-5

Chapter 6 Development of Germ Cells in the Mouse

In mammals, germ cells are induced from a population of cells at the base of the allantois. This regulative mechanism of germ line induction depends on Bmp signals and a combination of epigenetic changes that silence somatic differentiation genes and activate pluripotency genes. RNA binding proteins are a conserved feature of germ cell development in mammals, and play critical roles in the establishment and maintenance of pluripotency. After their specification, germ cells move through the gut to the gonads under the influence of migratory and attractive cues. In the gonad, germ cells initiate sex-specific differentiation. Germ cells that arrive in the ovary enter meiosis, whereas germ cells that arrive in the testis undergo mitotic arrest. Entry into meiosis is controlled by retinoic acid signals that are blocked in the testis. The signals regulating mitotic arrest in the testis are still not completely understood, but likely involve RNA-binding proteins. Epigenetic reprograming occurs during specification, migratory stages, and sex-specific stages, when maternal and paternal imprints are established. The facility of transitions between germ cells and stem cells suggests a close relationship among their genomic programs. © 2008 Elsevier Inc. All rights reserved.

Authors
Durcova-Hills, G; Capel, B
MLA Citation
Durcova-Hills, G, and Capel, B. "Chapter 6 Development of Germ Cells in the Mouse." Current Topics in Developmental Biology 83 (2008): 185-212.
Source
scival
Published In
Current topics in developmental biology
Volume
83
Publish Date
2008
Start Page
185
End Page
212
DOI
10.1016/S0070-2153(08)00406-7

Fibroblast growth factor receptor 2 regulates proliferation and Sertoli differentiation during male sex determination.

Targeted mutagenesis of Fgf9 in mice causes male-to-female sex reversal. Among the four FGF receptors, FGFR2 showed two highly specific patterns based on antibody staining, suggesting that it might be the receptor-mediating FGF9 signaling in the gonad. FGFR2 was detected at the plasma membrane in proliferating coelomic epithelial cells and in the nucleus in Sertoli progenitor cells. This expression pattern suggested that Fgfr2 might play more than one role in testis development. To test the hypothesis that Fgfr2 is required for male sex determination, we crossed mice carrying a floxed allele of Fgfr2 with two different Cre lines to induce a temporal or cell-specific deletion of this receptor. Results show that deletion of Fgfr2 in embryonic gonads phenocopies deletion of Fgf9 and leads to male-to-female sex reversal. Using these two Cre lines, we provide the first genetic evidence that Fgfr2 plays distinct roles in proliferation and Sertoli cell differentiation during testis development.

Authors
Kim, Y; Bingham, N; Sekido, R; Parker, KL; Lovell-Badge, R; Capel, B
MLA Citation
Kim, Y, Bingham, N, Sekido, R, Parker, KL, Lovell-Badge, R, and Capel, B. "Fibroblast growth factor receptor 2 regulates proliferation and Sertoli differentiation during male sex determination." Proc Natl Acad Sci U S A 104.42 (October 16, 2007): 16558-16563.
PMID
17940049
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
104
Issue
42
Publish Date
2007
Start Page
16558
End Page
16563
DOI
10.1073/pnas.0702581104

A high-resolution anatomical ontology of the developing murine genitourinary tract.

Cataloguing gene expression during development of the genitourinary tract will increase our understanding not only of this process but also of congenital defects and disease affecting this organ system. We have developed a high-resolution ontology with which to describe the subcompartments of the developing murine genitourinary tract. This ontology incorporates what can be defined histologically and begins to encompass other structures and cell types already identified at the molecular level. The ontology is being used to annotate in situ hybridisation data generated as part of the Genitourinary Development Molecular Anatomy Project (GUDMAP), a publicly available data resource on gene and protein expression during genitourinary development. The GUDMAP ontology encompasses Theiler stage (TS) 17-27 of development as well as the sexually mature adult. It has been written as a partonomic, text-based, hierarchical ontology that, for the embryological stages, has been developed as a high-resolution expansion of the existing Edinburgh Mouse Atlas Project (EMAP) ontology. It also includes group terms for well-characterised structural and/or functional units comprising several sub-structures, such as the nephron and juxtaglomerular complex. Each term has been assigned a unique identification number. Synonyms have been used to improve the success of query searching and maintain wherever possible existing EMAP terms relating to this organ system. We describe here the principles and structure of the ontology and provide representative diagrammatic, histological, and whole mount and section RNA in situ hybridisation images to clarify the terms used within the ontology. Visual examples of how terms appear in different specimen types are also provided.

Authors
Little, MH; Brennan, J; Georgas, K; Davies, JA; Davidson, DR; Baldock, RA; Beverdam, A; Bertram, JF; Capel, B; Chiu, HS; Clements, D; Cullen-McEwen, L; Fleming, J; Gilbert, T; Herzlinger, D; Houghton, D; Kaufman, MH; Kleymenova, E; Koopman, PA; Lewis, AG; McMahon, AP; Mendelsohn, CL; Mitchell, EK; Rumballe, BA; Sweeney, DE; Valerius, MT; Yamada, G; Yang, Y; Yu, J
MLA Citation
Little, MH, Brennan, J, Georgas, K, Davies, JA, Davidson, DR, Baldock, RA, Beverdam, A, Bertram, JF, Capel, B, Chiu, HS, Clements, D, Cullen-McEwen, L, Fleming, J, Gilbert, T, Herzlinger, D, Houghton, D, Kaufman, MH, Kleymenova, E, Koopman, PA, Lewis, AG, McMahon, AP, Mendelsohn, CL, Mitchell, EK, Rumballe, BA, Sweeney, DE, Valerius, MT, Yamada, G, Yang, Y, and Yu, J. "A high-resolution anatomical ontology of the developing murine genitourinary tract." Gene Expr Patterns 7.6 (June 2007): 680-699.
PMID
17452023
Source
pubmed
Published In
Gene Expression Patterns
Volume
7
Issue
6
Publish Date
2007
Start Page
680
End Page
699
DOI
10.1016/j.modgep.2007.03.002

Optimized regimen for expression of heat-inducible Cre in mice.

Authors
DiNapoli, L; Dietrich, P; Capel, B
MLA Citation
DiNapoli, L, Dietrich, P, and Capel, B. "Optimized regimen for expression of heat-inducible Cre in mice." Biotechniques 42.6 (June 2007): 710-714.
PMID
17612293
Source
pubmed
Published In
BioTechniques
Volume
42
Issue
6
Publish Date
2007
Start Page
710
End Page
714

Germ cell depletion does not alter the morphogenesis of the fetal testis or ovary in the red-eared slider turtle (Trachemys scripta).

In the red-eared slider turtle, Trachemys scripta, both prospective male and female gonads contain primitive cord structures at the time when the gonad first forms. Primordial germ cells arrive in the gonad and accumulate on the coelomic surface. If testis development is initiated, these cords develop further at the same time that germ cells migrate from the coelomic surface and become sequestered in the interior of the cords. In contrast, in the developing ovary germ cells proliferate in a defined cortical domain, while the primitive cords regress and form flattened lacunae in the medulla. Because of their intimate association with these developmental processes, we investigated whether germ cells were required in turtles to establish the morphology of the fetal testis and ovary. We present evidence that normal morphological development of the fetal gonad occurs in both sexes in T. scripta after germ cell depletion, suggesting a conservation of developmental mechanisms across vertebrates.

Authors
DiNapoli, L; Capel, B
MLA Citation
DiNapoli, L, and Capel, B. "Germ cell depletion does not alter the morphogenesis of the fetal testis or ovary in the red-eared slider turtle (Trachemys scripta)." J Exp Zool B Mol Dev Evol 308.3 (May 15, 2007): 236-241.
PMID
17041961
Source
pubmed
Published In
Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
Volume
308
Issue
3
Publish Date
2007
Start Page
236
End Page
241
DOI
10.1002/jez.b.21136

A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation.

One of the earliest morphological changes during testicular differentiation is the establishment of an XY specific vasculature. The testis vascular system is derived from mesonephric endothelial cells that migrate into the gonad. In the XX gonad, mesonephric cell migration and testis vascular development are inhibited by WNT4 signaling. In Wnt4 mutant XX gonads, endothelial cells migrate from the mesonephros and form a male-like coelomic vessel. Interestingly, this process occurs in the absence of other obvious features of testis differentiation, suggesting that Wnt4 specifically inhibits XY vascular development. Consequently, the XX Wnt4 mutant mice presented an opportunity to focus a gene expression screen on the processes of mesonephric cell migration and testicular vascular development. We compared differences in gene expression between XY Wnt4+/+ and XX Wnt4+/+ gonads and between XX Wnt4+/+ and XX Wnt4+/+ gonads to identify sets of genes similarly upregulated in wildtype XY gonads and XX mutant gonads or upregulated in XX gonads as compared to XY gonads and XX mutant gonads. We show that several genes identified in the first set are expressed in vascular domains, and have predicted functions related to cell migration or vascular development. However, the expression patterns and known functions of other genes are not consistent with roles in these processes. This screen has identified candidates for regulation of sex specific vascular development, and has implicated a role for WNT4 signaling in the development of Sertoli and germ cell lineages not immediately obvious from previous phenotypic analyses.

Authors
Coveney, D; Ross, AJ; Slone, JD; Capel, B
MLA Citation
Coveney, D, Ross, AJ, Slone, JD, and Capel, B. "A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation." Gene Expr Patterns 7.1-2 (January 2007): 82-92.
PMID
16844427
Source
pubmed
Published In
Gene Expression Patterns
Volume
7
Issue
1-2
Publish Date
2007
Start Page
82
End Page
92
DOI
10.1016/j.modgep.2006.05.012

Corrigendum to "A high-resolution anatomical ontology of the developing murine genitourinary tract" [Gene Expression Patterns 7 (2007) 680-699] (DOI:10.1016/j.modgep.2007.03.002)

Authors
Little, MH; Brennan, J; Georgas, K; Davies, JA; Davidson, DR; Baldock, RA; Beverdam, A; Bertram, JF; Capel, B; Chiu, HS; Clements, D; Cullen-McEwen, L; Fleming, J; Gilbert, T; Herzlinger, D; Houghton, D; Kaufman, MH; Kleymenova, E; Koopman, PA; Lewis, AG; McMahon, AP; Mendelsohn, CL; Mitchell, EK; Rumballe, BA; Sweeney, DE; Valerius, MT; Yamada, G; Yang, Y; Yu, J
MLA Citation
Little, MH, Brennan, J, Georgas, K, Davies, JA, Davidson, DR, Baldock, RA, Beverdam, A, Bertram, JF, Capel, B, Chiu, HS, Clements, D, Cullen-McEwen, L, Fleming, J, Gilbert, T, Herzlinger, D, Houghton, D, Kaufman, MH, Kleymenova, E, Koopman, PA, Lewis, AG, McMahon, AP, Mendelsohn, CL, Mitchell, EK, Rumballe, BA, Sweeney, DE, Valerius, MT, Yamada, G, Yang, Y, and Yu, J. "Corrigendum to "A high-resolution anatomical ontology of the developing murine genitourinary tract" [Gene Expression Patterns 7 (2007) 680-699] (DOI:10.1016/j.modgep.2007.03.002)." Gene Expression Patterns 8.1 (2007): 47-50.
Source
scival
Published In
Gene Expression Patterns
Volume
8
Issue
1
Publish Date
2007
Start Page
47
End Page
50
DOI
10.1016/j.modgep.2007.07.003

Bmp7 regulates germ cell proliferation in mouse fetal gonads.

Relatively little is known regarding the signals that regulate the proliferation and sex-specific development of germ cells during mammalian fetal gonad differentiation. Members of the bone morphogenetic protein (BMP) family have been identified as key regulators of germ cells in the Drosophila gonad. Here we show that in mice Bmp7 is expressed in gonads of both sexes and is required for germ cell proliferation during a narrow window of development between 10.5-11.5 days post coitum (dpc). The proliferation defect is more severe in male than in female embryos suggesting that there are sexually dimorphic compensatory pathways. BMP signaling appears to be an evolutionarily conserved pathway regulating embryonic germ cell proliferation in vertebrate and invertebrate species.

Authors
Ross, A; Munger, S; Capel, B
MLA Citation
Ross, A, Munger, S, and Capel, B. "Bmp7 regulates germ cell proliferation in mouse fetal gonads." Sex Dev 1.2 (2007): 127-137.
PMID
18391523
Source
pubmed
Published In
Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation
Volume
1
Issue
2
Publish Date
2007
Start Page
127
End Page
137
DOI
10.1159/000100034

R-spondin1 tips the balance in sex determination.

Authors
Capel, B
MLA Citation
Capel, B. "R-spondin1 tips the balance in sex determination." Nat Genet 38.11 (November 2006): 1233-1234.
PMID
17072299
Source
pubmed
Published In
Nature Genetics
Volume
38
Issue
11
Publish Date
2006
Start Page
1233
End Page
1234
DOI
10.1038/ng1106-1233

Successful management of orbital cellulitis and temporary visual loss after blepharoplasty.

Authors
Chiu, ES; Capell, BC; Press, R; Aston, SJ; Jelks, EB; Jelks, GW
MLA Citation
Chiu, ES, Capell, BC, Press, R, Aston, SJ, Jelks, EB, and Jelks, GW. "Successful management of orbital cellulitis and temporary visual loss after blepharoplasty." Plast Reconstr Surg 118.3 (September 2006): 67e-72e. (Review)
PMID
16932160
Source
pubmed
Published In
Plastic and Reconstructive Surgery
Volume
118
Issue
3
Publish Date
2006
Start Page
67e
End Page
72e
DOI
10.1097/01.prs.0000233031.17109.c6

Balancing the bipotential gonad between alternative organ fates: a new perspective on an old problem.

The embryonic gonads give rise to one of two morphologically and functionally different organs, a testis or an ovary. Sex determination is the embryonic process that determines the developmental fate of the gonad. In mammals, sex determination is regulated by a DNA binding protein encoded on the Y chromosome, Sry, and it's downstream mediator, Sox9, which trigger testis determination in the bipotential gonad. However, evidence suggests that the extracellular signals. Fgf9 and Wnt4, are also required to establish divergent organogenesis of the gonad. In this review, we discuss how these extracellular signals interface with cell-autonomous factors to determine the fate of the mammalian gonad, and we derive a model that could provide a molecular explanation for testis determination in vertebrates where Sry is absent.

Authors
Kim, Y; Capel, B
MLA Citation
Kim, Y, and Capel, B. "Balancing the bipotential gonad between alternative organ fates: a new perspective on an old problem." Dev Dyn 235.9 (September 2006): 2292-2300. (Review)
PMID
16881057
Source
pubmed
Published In
Developmental Dynamics
Volume
235
Issue
9
Publish Date
2006
Start Page
2292
End Page
2300
DOI
10.1002/dvdy.20894

Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination.

The genes encoding members of the wingless-related MMTV integration site (WNT) and fibroblast growth factor (FGF) families coordinate growth, morphogenesis, and differentiation in many fields of cells during development. In the mouse, Fgf9 and Wnt4 are expressed in gonads of both sexes prior to sex determination. Loss of Fgf9 leads to XY sex reversal, whereas loss of Wnt4 results in partial testis development in XX gonads. However, the relationship between these signals and the male sex-determining gene, Sry, was unknown. We show through gain- and loss-of-function experiments that fibroblast growth factor 9 (FGF9) and WNT4 act as opposing signals to regulate sex determination. In the mouse XY gonad, Sry normally initiates a feed-forward loop between Sox9 and Fgf9, which up-regulates Fgf9 and represses Wnt4 to establish the testis pathway. Surprisingly, loss of Wnt4 in XX gonads is sufficient to up-regulate Fgf9 and Sox9 in the absence of Sry. These data suggest that the fate of the gonad is controlled by antagonism between Fgf9 and Wnt4. The role of the male sex-determining switch--Sry in the case of mammals--is to tip the balance between these underlying patterning signals. In principle, sex determination in other vertebrates may operate through any switch that introduces an imbalance between these two signaling pathways.

Authors
Kim, Y; Kobayashi, A; Sekido, R; DiNapoli, L; Brennan, J; Chaboissier, M-C; Poulat, F; Behringer, RR; Lovell-Badge, R; Capel, B
MLA Citation
Kim, Y, Kobayashi, A, Sekido, R, DiNapoli, L, Brennan, J, Chaboissier, M-C, Poulat, F, Behringer, RR, Lovell-Badge, R, and Capel, B. "Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination." PLoS Biol 4.6 (June 2006): e187-.
PMID
16700629
Source
pubmed
Published In
PLoS biology
Volume
4
Issue
6
Publish Date
2006
Start Page
e187
DOI
10.1371/journal.pbio.0040187

FGF9 promotes survival of germ cells in the fetal testis.

In addition to its role in somatic cell development in the testis, our data have revealed a role for Fgf9 in XY germ cell survival. In Fgf9-null mice, germ cells in the XY gonad decline in numbers after 11.5 days post coitum (dpc), while germ cell numbers in XX gonads are unaffected. We present evidence that germ cells resident in the XY gonad become dependent on FGF9 signaling between 10.5 dpc and 11.5 dpc, and that FGF9 directly promotes XY gonocyte survival after 11.5 dpc, independently from Sertoli cell differentiation. Furthermore, XY Fgf9-null gonads undergo true male-to-female sex reversal as they initiate but fail to maintain the male pathway and subsequently express markers of ovarian differentiation (Fst and Bmp2). By 14.5 dpc, these gonads contain germ cells that enter meiosis synchronously with ovarian gonocytes. FGF9 is necessary for 11.5 dpc XY gonocyte survival and is the earliest reported factor with a sex-specific role in regulating germ cell survival.

Authors
DiNapoli, L; Batchvarov, J; Capel, B
MLA Citation
DiNapoli, L, Batchvarov, J, and Capel, B. "FGF9 promotes survival of germ cells in the fetal testis." Development 133.8 (April 2006): 1519-1527.
PMID
16540514
Source
pubmed
Published In
Development (Cambridge)
Volume
133
Issue
8
Publish Date
2006
Start Page
1519
End Page
1527
DOI
10.1242/dev.02303

Retinoic acid regulates sex-specific timing of meiotic initiation in mice.

In mammals, meiosis is initiated at different time points in males and females, but the mechanism underlying this difference is unknown. Female germ cells begin meiosis during embryogenesis. In males, embryonic germ cells undergo G0/G1 mitotic cell cycle arrest, and meiosis begins after birth. In mice, the Stimulated by Retinoic Acid Gene 8 (Stra8) has been found to be required for the transition into meiosis in both female and male germ cells. Stra8 is expressed in embryonic ovaries just before meiotic initiation, whereas its expression in testes is first detected after birth. Here we examine the mechanism underlying the sex-specific timing of Stra8 expression and meiotic initiation in mice. Our work shows that signaling by retinoic acid (RA), an active derivative of vitamin A, is required for Stra8 expression and thereby meiotic initiation in embryonic ovaries. We also discovered that RA is sufficient to induce Stra8 expression in embryonic testes and in vitamin A-deficient adult testes in vivo. Finally, our results show that cytochrome p450 (CYP)-mediated RA metabolism prevents premature Stra8 expression in embryonic testes. Treatment with an inhibitor specific to RA-metabolizing enzymes indicates that a cytochrome p450 from the 26 family (CYP26) is responsible for delaying Stra8 expression in embryonic testes. Sex-specific regulation of RA signaling thus plays an essential role in meiotic initiation in embryonic ovaries and precludes its occurrence in embryonic testes. Because RA signaling regulates Stra8 expression in both embryonic ovaries and adult testes, this portion of the meiotic initiation pathway may be identical in both sexes.

Authors
Koubova, J; Menke, DB; Zhou, Q; Capel, B; Griswold, MD; Page, DC
MLA Citation
Koubova, J, Menke, DB, Zhou, Q, Capel, B, Griswold, MD, and Page, DC. "Retinoic acid regulates sex-specific timing of meiotic initiation in mice." Proc Natl Acad Sci U S A 103.8 (February 21, 2006): 2474-2479.
PMID
16461896
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
103
Issue
8
Publish Date
2006
Start Page
2474
End Page
2479
DOI
10.1073/pnas.0510813103

Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination

The genes encoding members of the wingless-related MMTV integration site (WNT) and fibroblast growth factor (FGF) families coordinate growth, morphogenesis, and differentiation in many fields of cells during development. In the mouse, Fgf9 and Wnt4 are expressed in gonads of both sexes prior to sex determination. Loss of Fgf9 leads to XY sex reversal, whereas loss of Wnt4 results in partial testis development in XX gonads. However, the relationship between these signals and the male sex-determining gene, Sry, was unknown. We show through gain- and loss-of-function experiments that fibroblast growth factor 9 (FGF9) and WNT4 act as opposing signals to regulate sex determination. In the mouse XY gonad, Sry normally initiates a feed-forward loop between Sox9 and Fgf9, which up-regulates Fgf9 and represses Wnt4 to establish the testis pathway. Surprisingly, loss of Wnt4 in XX gonads is sufficient to up-regulate Fgf9 and Sox9 in the absence of Sry. These data suggest that the fate of the gonad is controlled by antagonism between Fgf9 and Wnt4. The role of the male sex-determining switch - Sry in the case of mammals - is to tip the balance between these underlying patterning signals. In principle, sex determination in other vertebrates may operate through any switch that introduces an imbalance between these two signaling pathways. © 2006 Kim et al.

Authors
Kim, Y; Kobayashi, A; Sekido, R; DiNapoli, L; Brennan, J; Chaboissier, M-C; Poulat, F; Behringer, RR; Lovell-Badge, R; Capel, B
MLA Citation
Kim, Y, Kobayashi, A, Sekido, R, DiNapoli, L, Brennan, J, Chaboissier, M-C, Poulat, F, Behringer, RR, Lovell-Badge, R, and Capel, B. "Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination." PLoS Biology 4.6 (2006): 1000-1009.
Source
scival
Published In
PLoS biology
Volume
4
Issue
6
Publish Date
2006
Start Page
1000
End Page
1009
DOI
10.1007/11558958_121

Temperature, genes, and sex: a comparative view of sex determination in Trachemys scripta and Mus musculus.

Sex determination, the step at which differentiation of males and females is initiated in the embryo, is of central importance to the propagation of species. There is a remarkable diversity of mechanisms by which sex determination is accomplished. In general these mechanisms fall into two categories: Genetic Sex Determination (GSD), which depends on genetic differences between the sexes, and Environmental Sex Determination (ESD), which depends on extrinsic cues. In this review we will consider these two means of determining sex with particular emphasis on two species: a species that depends on GSD, Mus musculus, and a species that depends on ESD, Trachemys scripta. Because the structural organization of the adult testis and ovary is very similar across vertebrates, most biologists had expected that the pathways downstream of the sex-determining switch would be conserved. However, emerging data indicate that not only are the initial sex determining mechanisms different, but the downstream pathways and morphogenetic events leading to the development of a testis or ovary also are different.

Authors
Yao, HH-C; Capel, B
MLA Citation
Yao, HH-C, and Capel, B. "Temperature, genes, and sex: a comparative view of sex determination in Trachemys scripta and Mus musculus." J Biochem 138.1 (July 2005): 5-12. (Review)
PMID
16046442
Source
pubmed
Published In
The Journal of Biochemistry
Volume
138
Issue
1
Publish Date
2005
Start Page
5
End Page
12
DOI
10.1093/jb/mvi097

The Ter mutation in the dead end gene causes germ cell loss and testicular germ cell tumours.

In mice, the Ter mutation causes primordial germ cell (PGC) loss in all genetic backgrounds. Ter is also a potent modifier of spontaneous testicular germ cell tumour (TGCT) susceptibility in the 129 family of inbred strains, and markedly increases TGCT incidence in 129-Ter/Ter males. In 129-Ter/Ter mice, some of the remaining PGCs transform into undifferentiated pluripotent embryonal carcinoma cells, and after birth differentiate into various cells and tissues that compose TGCTs. Here, we report the positional cloning of Ter, revealing a point mutation that introduces a termination codon in the mouse orthologue (Dnd1) of the zebrafish dead end (dnd) gene. PGC deficiency is corrected both with bacterial artificial chromosomes that contain Dnd1 and with a Dnd1-encoding transgene. Dnd1 is expressed in fetal gonads during the critical period when TGCTs originate. DND1 has an RNA recognition motif and is most similar to the apobec complementation factor, a component of the cytidine to uridine RNA-editing complex. These results suggest that Ter may adversely affect essential aspects of RNA biology during PGC development. DND1 is the first protein known to have an RNA recognition motif directly implicated as a heritable cause of spontaneous tumorigenesis. TGCT development in the 129-Ter mouse strain models paediatric TGCT in humans. This work will have important implications for our understanding of the genetic control of TGCT pathogenesis and PGC biology.

Authors
Youngren, KK; Coveney, D; Peng, X; Bhattacharya, C; Schmidt, LS; Nickerson, ML; Lamb, BT; Deng, JM; Behringer, RR; Capel, B; Rubin, EM; Nadeau, JH; Matin, A
MLA Citation
Youngren, KK, Coveney, D, Peng, X, Bhattacharya, C, Schmidt, LS, Nickerson, ML, Lamb, BT, Deng, JM, Behringer, RR, Capel, B, Rubin, EM, Nadeau, JH, and Matin, A. "The Ter mutation in the dead end gene causes germ cell loss and testicular germ cell tumours." Nature 435.7040 (May 19, 2005): 360-364.
PMID
15902260
Source
pubmed
Published In
Nature
Volume
435
Issue
7040
Publish Date
2005
Start Page
360
End Page
364
DOI
10.1038/nature03595

Signaling at the crossroads of gonad development.

In mammals, the gonads arise as bipotential primordia that are capable of developing as either testes or ovaries. Expression of the Y-linked gene Sry in the XY gonad initiates testis differentiation; in the absence of Sry, ovarian pathways prevail. Although the molecular targets of SRY are not known, many of the early cellular and morphological events that occur downstream of Sry have been characterized. These include increased cell proliferation, Sertoli cell differentiation, testis cord formation, development of a testis-specific vasculature and differentiation of interstitial lineages. Recently, several of the molecular signals that direct these processes have been identified. In addition, the pathways that suppress features of testis development in the XX gonad are being elucidated.

Authors
Ross, AJ; Capel, B
MLA Citation
Ross, AJ, and Capel, B. "Signaling at the crossroads of gonad development." Trends Endocrinol Metab 16.1 (January 2005): 19-25. (Review)
PMID
15620545
Source
pubmed
Published In
Trends in Endocrinology and Metabolism
Volume
16
Issue
1
Publish Date
2005
Start Page
19
End Page
25
DOI
10.1016/j.tem.2004.11.004

New clues to the genetic basis of testicular cancer suggest dead end mutations

Authors
Peng, X; Bhattacharya, C; Jian, MD; Behringer, R; Youngren, K; Lamb, B; Coveney, D; Capel, B; Nickerson, M; Schmidt, L; Rubin, E
MLA Citation
Peng, X, Bhattacharya, C, Jian, MD, Behringer, R, Youngren, K, Lamb, B, Coveney, D, Capel, B, Nickerson, M, Schmidt, L, and Rubin, E. "New clues to the genetic basis of testicular cancer suggest dead end mutations." Cancer Biology and Therapy 4.6 (2005): 10DUMMY-.
Source
scival
Published In
Cancer Biology and Therapy
Volume
4
Issue
6
Publish Date
2005
Start Page
10DUMMY

Frank Lillie's freemartin: illuminating the pathway to 21st century reproductive endocrinology.

Authors
Capel, B; Coveney, D
MLA Citation
Capel, B, and Coveney, D. "Frank Lillie's freemartin: illuminating the pathway to 21st century reproductive endocrinology." J Exp Zool A Comp Exp Biol 301.11 (November 1, 2004): 853-856.
PMID
15673106
Source
pubmed
Published In
Journal of Experimental Zoology Part A: Comparative Experimental Biology
Volume
301
Issue
11
Publish Date
2004
Start Page
853
End Page
856
DOI
10.1002/jez.a.107

Cellular mechanisms of sex determination in the red-eared slider turtle, Trachemys scripta.

In all vertebrates sex determination is the step at which development of a testis or ovary is initiated in the bipotential gonad. Although Mus musculus and the red-eared slider turtle, Trachemys scripta, use different mechanisms to initiate organogenesis of the testis (the Y-linked gene, Sry, in the mouse vs. the incubation temperature of the egg in the turtle), the structure of the adult testis is strikingly similar. We have identified several cellular mechanisms involved in testis organogenesis in mouse. Here we investigated whether these cellular mechanisms are conserved in T. scripta downstream of the temperature-dependent switch. Cell tracing experiments indicated that the coelomic epithelium in T. scripta contributes precursors for Sertoli cells and interstitial cells as in mouse. However, we detect no male-specific mesonephric cell migration, a process required for the de novo testis cord-forming process in mouse. In contrast to mouse gonads, where no cord structure is discernible until after the divergence of testis development, we find that primitive sex cords continuous with the coelomic epithelium exist in all T. scripta gonads from the earliest bipotential stages examined. We conclude that typical testis architecture results from the maintenance and elaboration of primitive sex cords in T. scripta rather than the assembly of de novo structures as in mouse.

Authors
Yao, HH-C; DiNapoli, L; Capel, B
MLA Citation
Yao, HH-C, DiNapoli, L, and Capel, B. "Cellular mechanisms of sex determination in the red-eared slider turtle, Trachemys scripta." Mech Dev 121.11 (November 2004): 1393-1401.
PMID
15454268
Source
pubmed
Published In
Mechanisms of Development
Volume
121
Issue
11
Publish Date
2004
Start Page
1393
End Page
1401
DOI
10.1016/j.mod.2004.06.001

Sox8 is expressed at similar levels in gonads of both sexes during the sex determining period in turtles.

A critical gene involved in mammalian sex determination and differentiation is the Sry-related gene Sox9. In reptiles, Sox9 resembles that of mammals in both structure and expression pattern in the developing gonad, but a causal role in male sex determination has not been established. A closely related gene, Sox8, is conserved in human, mouse, and trout and is expressed in developing testes and not developing ovaries in mouse. In this study, we tested the possibility of Sox8 being important for sex determination or sex differentiation in the red-eared slider turtle Trachemys scripta, in which sex is determined by egg incubation temperature between stages 15 and 20. We cloned partial turtle Sox8 and anti-Müllerian hormone (Amh) cDNAs, and analyzed the expression patterns of these genes in developing gonads by reverse transcriptase-polymerase chain reaction and whole-mount in situ hybridization. While Amh is expressed more strongly in males than in females at stage 17, Sox8 is expressed at similar levels in males and females throughout the sex-determining period. These observations suggest that differential transcription of Sox8 is not responsible for regulation of Amh, nor responsible for sex determination in turtle.

Authors
Takada, S; DiNapoli, L; Capel, B; Koopman, P
MLA Citation
Takada, S, DiNapoli, L, Capel, B, and Koopman, P. "Sox8 is expressed at similar levels in gonads of both sexes during the sex determining period in turtles." Dev Dyn 231.2 (October 2004): 387-395.
PMID
15366016
Source
pubmed
Published In
Developmental Dynamics
Volume
231
Issue
2
Publish Date
2004
Start Page
387
End Page
395
DOI
10.1002/dvdy.20132

Fgf9 induces proliferation and nuclear localization of FGFR2 in Sertoli precursors during male sex determination.

Recently, we demonstrated that loss of Fgf9 results in a block of testis development and a male to female sex-reversed phenotype; however, the function of Fgf9 in sex determination was unknown. We now show that Fgf9 is necessary for two steps of testis development just downstream of the male sex-determining gene, Sry: (1) for the proliferation of a population of cells that give rise to Sertoli progenitors; and (2) for the nuclear localization of an FGF receptor (FGFR2) in Sertoli cell precursors. The nuclear localization of FGFR2 coincides with the initiation of Sry expression and the nuclear localization of SOX9 during the early differentiation of Sertoli cells and the determination of male fate.

Authors
Schmahl, J; Kim, Y; Colvin, JS; Ornitz, DM; Capel, B
MLA Citation
Schmahl, J, Kim, Y, Colvin, JS, Ornitz, DM, and Capel, B. "Fgf9 induces proliferation and nuclear localization of FGFR2 in Sertoli precursors during male sex determination." Development 131.15 (August 2004): 3627-3636.
PMID
15229180
Source
pubmed
Published In
Development (Cambridge)
Volume
131
Issue
15
Publish Date
2004
Start Page
3627
End Page
3636
DOI
10.1242/dev.01239

Disrupted gonadogenesis and male-to-female sex reversal in Pod1 knockout mice.

Congenital defects in genital and/or gonadal development occur in 1 in 1000 humans, but the molecular basis for these defects in most cases remains undefined. We show that the basic helix-loop-helix transcription factor Pod1 (capsulin/epicardin/Tcf21) is essential for normal development of the testes and ovaries, and hence for sexual differentiation. The gonads of Pod1 knockout (KO) mice were markedly hypoplastic, and the urogenital tracts of both XX and XY mice remained indistinguishable throughout embryogenesis. Within Pod1 KO gonads, the number of cells expressing the cholesterol side-chain cleavage enzyme (Scc) was increased markedly. Biochemical and genetic approaches demonstrated that Pod1 transcriptionally represses steroidogenic factor 1 (Sf1/Nr5a1/Ad4BP), an orphan nuclear receptor that regulates the expression of multiple genes (including Scc) that mediate sexual differentiation. Our results establish that Pod1 is essential for gonadal development, and place it in a transcriptional network that orchestrates cell fate decisions in gonadal progenitors.

Authors
Cui, S; Ross, A; Stallings, N; Parker, KL; Capel, B; Quaggin, SE
MLA Citation
Cui, S, Ross, A, Stallings, N, Parker, KL, Capel, B, and Quaggin, SE. "Disrupted gonadogenesis and male-to-female sex reversal in Pod1 knockout mice." Development 131.16 (August 2004): 4095-4105.
PMID
15289436
Source
pubmed
Published In
Development (Cambridge)
Volume
131
Issue
16
Publish Date
2004
Start Page
4095
End Page
4105
DOI
10.1242/dev.01266

One tissue, two fates: molecular genetic events that underlie testis versus ovary development.

Authors
Brennan, J; Capel, B
MLA Citation
Brennan, J, and Capel, B. "One tissue, two fates: molecular genetic events that underlie testis versus ovary development." Nat Rev Genet 5.7 (July 2004): 509-521. (Review)
PMID
15211353
Source
pubmed
Published In
Nature Reviews Genetics
Volume
5
Issue
7
Publish Date
2004
Start Page
509
End Page
521
DOI
10.1038/nrg1381

Follistatin operates downstream of Wnt4 in mammalian ovary organogenesis.

Wnt4(-/-) XX gonads display features normally associated with testis differentiation, suggesting that WNT4 actively represses elements of the male pathway during ovarian development. Here, we show that follistatin (Fst), which encodes a TGFbeta superfamily binding protein, is a downstream component of Wnt4 signaling. Fst inhibits formation of the XY-specific coelomic vessel in XX gonads. In addition, germ cells in the ovarian cortex are almost completely lost in both Wnt4 and Fst null gonads before birth. Thus, we propose that WNT4 acts through FST to regulate vascular boundaries and maintain germ cell survival in the ovary.

Authors
Yao, HHC; Matzuk, MM; Jorgez, CJ; Menke, DB; Page, DC; Swain, A; Capel, B
MLA Citation
Yao, HHC, Matzuk, MM, Jorgez, CJ, Menke, DB, Page, DC, Swain, A, and Capel, B. "Follistatin operates downstream of Wnt4 in mammalian ovary organogenesis." Dev Dyn 230.2 (June 2004): 210-215.
PMID
15162500
Source
pubmed
Published In
Developmental Dynamics
Volume
230
Issue
2
Publish Date
2004
Start Page
210
End Page
215
DOI
10.1002/dvdy.20042

AMH induces mesonephric cell migration in XX gonads.

Migration of mesonephric cells into XY gonads is a critical early event in testis cord formation. Based on the fact that anti-Müllerian hormone (AMH) can induce testis cord formation in XX gonads, we investigated whether AMH plays a role in the induction of cell migration. Addition of recombinant AMH induced mesonephric migration into XX gonads in culture. AMH-treated XX gonads displayed increased vascular development and altered morphology of the coelomic epithelium, both features of normal testis differentiation. AMH did not induce markers of Sertoli or Leydig cell differentiation. We examined early testis development in Amh-deficient mice, but found no abnormalities, suggesting that any function AMH may have in vivo is redundant. Other transforming growth factor (TGF-beta) family proteins, bone morphogenetic proteins (BMP2 and BMP4) show similar inductive effects on XX gonads in culture. Although neither BMP2 nor BMP4 is expressed in embryonic XY gonads, our findings suggest that a TGF-beta signalling pathway endogenous to the XY gonad may be involved in regulation of mesonephric cell migration. The factors involved in this process remain to be identified.

Authors
Ross, AJ; Tilman, C; Yao, H; MacLaughlin, D; Capel, B
MLA Citation
Ross, AJ, Tilman, C, Yao, H, MacLaughlin, D, and Capel, B. "AMH induces mesonephric cell migration in XX gonads." Mol Cell Endocrinol 211.1-2 (December 15, 2003): 1-7.
PMID
14656469
Source
pubmed
Published In
Molecular and Cellular Endocrinology
Volume
211
Issue
1-2
Publish Date
2003
Start Page
1
End Page
7

Meiotic germ cells antagonize mesonephric cell migration and testis cord formation in mouse gonads.

The developmental fate of primordial germ cells in the mammalian gonad depends on their environment. In the XY gonad, Sry induces a cascade of molecular and cellular events leading to the organization of testis cords. Germ cells are sequestered inside testis cords by 12.5 dpc where they arrest in mitosis. If the testis pathway is not initiated, germ cells spontaneously enter meiosis by 13.5 dpc, and the gonad follows the ovarian fate. We have previously shown that some testis-specific events, such as mesonephric cell migration, can be experimentally induced into XX gonads prior to 12.5 dpc. However, after that time, XX gonads are resistant to the induction of cell migration. In current experiments, we provide evidence that this effect is dependent on XX germ cells rather than on XX somatic cells. We show that, although mesonephric cell migration cannot be induced into normal XX gonads at 14.5 dpc, it can be induced into XX gonads depleted of germ cells. We also show that when 14.5 dpc XX somatic cells are recombined with XY somatic cells, testis cord structures form normally; however, when XX germ cells are recombined with XY somatic cells, cord structures are disrupted. Sandwich culture experiments suggest that the inhibitory effect of XX germ cells is mediated through short-range interactions rather than through a long-range diffusible factor. The developmental stage at which XX germ cells show a disruptive effect on the male pathway is the stage at which meiosis is normally initiated, based on the immunodetection of meiotic markers. We suggest that at the stage when germ cells commit to meiosis, they reinforce ovarian fate by antagonizing the testis pathway.

Authors
Yao, HH-C; DiNapoli, L; Capel, B
MLA Citation
Yao, HH-C, DiNapoli, L, and Capel, B. "Meiotic germ cells antagonize mesonephric cell migration and testis cord formation in mouse gonads." Development 130.24 (December 2003): 5895-5902.
PMID
14561636
Source
pubmed
Published In
Development (Cambridge)
Volume
130
Issue
24
Publish Date
2003
Start Page
5895
End Page
5902
DOI
10.1242/dev.00836

Endothelial and steroidogenic cell migration are regulated by WNT4 in the developing mammalian gonad.

The signalling molecule WNT4 has been associated with sex reversal phenotypes in mammals. Here we show that the role of WNT4 in gonad development is to pattern the sex-specific vasculature and to regulate steroidogenic cell recruitment. Vascular formation and steroid production in the mammalian gonad occur in a sex-specific manner. During testis development, endothelial cells migrate from the mesonephros into the gonad to form a coelomic blood vessel. Leydig cells differentiate and produce steroid hormones a day later. Neither of these events occurs in the XX gonad. We show that WNT4 represses mesonephric endothelial and steroidogenic cell migration in the XX gonad, preventing the formation of a male-specific coelomic blood vessel and the production of steroids. In the XY gonad, Wnt4 expression is downregulated after sex determination. Transgenic misexpression of Wnt4 in the embryonic testis did not inhibit coelomic vessel formation but vascular pattern was affected. Leydig cell differentiation was not affected in these transgenic animals and our data implies that Wnt4 does not regulate steroidogenic cell differentiation but represses the migration of steroidogenic adrenal precursors into the gonad. These studies provide a model for understanding how the same signalling molecule can act on two different cell types to coordinate sex development.

Authors
Jeays-Ward, K; Hoyle, C; Brennan, J; Dandonneau, M; Alldus, G; Capel, B; Swain, A
MLA Citation
Jeays-Ward, K, Hoyle, C, Brennan, J, Dandonneau, M, Alldus, G, Capel, B, and Swain, A. "Endothelial and steroidogenic cell migration are regulated by WNT4 in the developing mammalian gonad." Development 130.16 (August 2003): 3663-3670.
PMID
12835383
Source
pubmed
Published In
Development (Cambridge)
Volume
130
Issue
16
Publish Date
2003
Start Page
3663
End Page
3670

Pin1 regulates the timing of mammalian primordial germ cell proliferation.

Primordial germ cells (PGCs) give rise to male and female germ cells to transmit the genome from generation to generation. Defects in PGC development often result in infertility. In the mouse embryo, PGCs undergo proliferation and expansion during and after their migration to the gonads from 8.5 to 13.5 days post coitum (dpc). We show that a peptidyl-prolyl isomerase, Pin1, is involved in the regulation of mammalian PGC proliferation. We discovered that both the male and female Pin1(-/-) mice had profound fertility defects. Investigation of the reproductive organs revealed significantly fewer germ cells in the adult Pin1(-/-) testes and ovaries than in wild type or heterozygotes, which resulted from Pin1(-/-) males and females being born with severely reduced number of gonocytes and oocytes. Further studies in 8.5 to 13.5 dpc Pin1(-/-) embryos showed that PGCs were allocated properly at the base of the allantois, but their cell expansion was progressively impaired, resulting in a markedly reduced number of PGCs at 13.5 dpc. Analyses using markers of cell cycle parameters and apoptosis revealed that Pin1(-/-) PGCs did not undergo cell cycle arrest or apoptosis. Instead, Pin1(-/-) PGCs had a lower BrdU labeling index compared with wild-type PGCs. We conclude that PGCs have a prolonged cell cycle in the absence of Pin1, which translates into fewer cell divisions and strikingly fewer Pin1(-/-) PGCs by the end of the proliferative phase. These results indicate that Pin1 regulates the timing of PGC proliferation during mouse embryonic development.

Authors
Atchison, FW; Capel, B; Means, AR
MLA Citation
Atchison, FW, Capel, B, and Means, AR. "Pin1 regulates the timing of mammalian primordial germ cell proliferation." Development 130.15 (August 2003): 3579-3586.
PMID
12810604
Source
pubmed
Published In
Development (Cambridge)
Volume
130
Issue
15
Publish Date
2003
Start Page
3579
End Page
3586

Cell proliferation is necessary for the determination of male fate in the gonad.

Cell proliferation has been shown to have multiple functions in development and pattern formation, including roles in growth, morphogenesis, and gene expression. Previously, we determined that the earliest known morphological event downstream of the male sex determining gene, Sry, is the induction of proliferation. In this study, we used proliferation inhibitors to block cell division during early gonad development, at stages before the XY gonad has committed to the testis pathway. Using the expression of sex-specific genes and the formation of testis morphology as markers of testis determination, we found that proliferation within a specific 8-h window was critical for the establishment of the male pathway and the formation of the testis. Inhibition of proliferation before or after this critical period led to smaller gonads, but did not block testis formation. The critical period of proliferation coincides with the initiation of Sry expression and is essential for the differentiation of Sertoli cells, suggesting that proliferation is a vital component of the initiation of the male pathway by Sry. We believe these studies suggest that proliferation is involved not only in the elaboration of organ pattern, but also in the choice between patterns (male and female) in the bipotential gonad.

Authors
Schmahl, J; Capel, B
MLA Citation
Schmahl, J, and Capel, B. "Cell proliferation is necessary for the determination of male fate in the gonad." Dev Biol 258.2 (June 15, 2003): 264-276.
PMID
12798287
Source
pubmed
Published In
Developmental Biology
Volume
258
Issue
2
Publish Date
2003
Start Page
264
End Page
276

Colocalization of WT1 and cell proliferation reveals conserved mechanisms in temperature-dependent sex determination.

During vertebrate development the gonad has two possible fates, the testis or the ovary. The choice between these fates is made by a variety of sex-determining mechanisms, from the sex-determining gene on the Y chromosome (Sry) in mammals, to nongenetic temperature-dependent systems in many reptiles. Despite the differences in the mechanisms at the top of the sex-determining cascade, the resulting morphology and many genes involved in early testis and ovarian development are common to most vertebrates, leading to the hypothesis that the underlying processes of sex determination are conserved. In this study, we examined the early steps of gonad development in the red-eared slider turtle (Trachemys scripta), a species that uses the temperature of egg incubation to determine sex. A dramatic increase in cell proliferation was observed in the male gonad during the earliest stages of sex determination. Using the localization of Wilms' Tumor suppressor 1 (WT1), we determined that this proliferation increase occurred in a population that contained pre-Sertoli cells. The proliferation of pre-Sertoli cells has been documented during sex determination in both mice and alligators, suggesting that proliferation of this cell type has an important role in vertebrate testis organogenesis and the determination of male fate.

Authors
Schmahl, J; Yao, HH; Pierucci-Alves, F; Capel, B
MLA Citation
Schmahl, J, Yao, HH, Pierucci-Alves, F, and Capel, B. "Colocalization of WT1 and cell proliferation reveals conserved mechanisms in temperature-dependent sex determination." Genesis 35.4 (April 2003): 193-201.
PMID
12717730
Source
pubmed
Published In
Genesis: the Journal of Genetics and Development
Volume
35
Issue
4
Publish Date
2003
Start Page
193
End Page
201
DOI
10.1002/gene.10176

Pdgfr-alpha mediates testis cord organization and fetal Leydig cell development in the XY gonad.

During testis development, the rapid morphological changes initiated by Sry require the coordinate integration of many signaling pathways. Based on the established role of the platelet-derived growth factor (PDGF) family of ligands and receptors in migration, proliferation, and differentiation of cells in various organ systems, we have investigated the role of PDGF in testis organogenesis. Analysis of expression patterns and characterization of the gonad phenotype in Pdgfr-alpha(-/-) embryos identified PDGFR-alpha as a critical mediator of signaling in the early testis at multiple steps of testis development. Pdgfr-alpha(-/-) XY gonads displayed disruptions in the organization of the vasculature and in the partitioning of interstitial and testis cord compartments. Closer examination revealed severe reductions in characteristic XY proliferation, mesonephric cell migration, and fetal Leydig cell differentiation. This work identifies PDGF signaling through the alpha receptor as an important event downstream of Sry in testis organogenesis and Leydig cell differentiation.

Authors
Brennan, J; Tilmann, C; Capel, B
MLA Citation
Brennan, J, Tilmann, C, and Capel, B. "Pdgfr-alpha mediates testis cord organization and fetal Leydig cell development in the XY gonad." Genes Dev 17.6 (March 15, 2003): 800-810.
PMID
12651897
Source
pubmed
Published In
Genes & development
Volume
17
Issue
6
Publish Date
2003
Start Page
800
End Page
810
DOI
10.1101/gad.1052503

Disruption of testis cords by cyclopamine or forskolin reveals independent cellular pathways in testis organogenesis.

Most studies to date indicate that the formation of testis cords is critical for proper Sertoli cell differentiation, inhibition of germ cell meiosis, and regulation of Leydig cell differentiation. However, the connections between these events are poorly understood. The objective of this study was to dissect the molecular and cellular relationships between these events in testis formation. We took advantage of the different effects of two hedgehog signaling inhibitors, cyclopamine and forskolin, on gonad explant cultures. Both hedgehog inhibitors phenocopied the disruptive effect of Dhh(-/-) on formation of testis cords without influencing Sertoli cell differentiation. However, they exhibited different effects on other cellular events during testis development. Treatment with cyclopamine did not affect inhibition of germ cell meiosis and mesonephric cell migration but caused defects in Leydig cell differentiation. In contrast, forskolin treatment induced germ cell meiosis, inhibited mesonephric cell migration, and had no effect on Leydig cell differentiation. By carefully contrasting the different effects of these two hedgehog inhibitors, we demonstrate that, although formation of testis cords and development of other cell types normally take place in a tightly regulated sequence, each of these events can occur independent of the others.

Authors
Yao, HH-C; Capel, B
MLA Citation
Yao, HH-C, and Capel, B. "Disruption of testis cords by cyclopamine or forskolin reveals independent cellular pathways in testis organogenesis." Dev Biol 246.2 (June 15, 2002): 356-365.
PMID
12051821
Source
pubmed
Published In
Developmental Biology
Volume
246
Issue
2
Publish Date
2002
Start Page
356
End Page
365
DOI
10.1006/dbio.2002.0663

Desert Hedgehog/Patched 1 signaling specifies fetal Leydig cell fate in testis organogenesis.

Establishment of the steroid-producing Leydig cell lineage is an event downstream of Sry that is critical for masculinization of mammalian embryos. Neither the origin of fetal Leydig cell precursors nor the signaling pathway that specifies the Leydig cell lineage is known. Based on the sex-specific expression patterns of Desert Hedgehog (Dhh) and its receptor Patched 1 (Ptch1) in XY gonads, we investigated the potential role of DHH/PTCH1 signaling in the origin and specification of fetal Leydig cells. Analysis of Dhh(-/-) XY gonads revealed that differentiation of fetal Leydig cells was severely defective. Defects in Leydig cell differentiation in Dhh(-/-) XY gonads did not result from failure of cell migration from the mesonephros, thought to be a possible source of Leydig cell precursors. Nor did DHH/PTCH1 signaling appear to be involved in the proliferation or survival of fetal Leydig precursors in the interstitium of the XY gonad. Instead, our results suggest that DHH/PTCH1 signaling triggers Leydig cell differentiation by up-regulating Steroidogenic Factor 1 and P450 Side Chain Cleavage enzyme expression in Ptch1-expressing precursor cells located outside testis cords.

Authors
Yao, HH-C; Whoriskey, W; Capel, B
MLA Citation
Yao, HH-C, Whoriskey, W, and Capel, B. "Desert Hedgehog/Patched 1 signaling specifies fetal Leydig cell fate in testis organogenesis." Genes Dev 16.11 (June 1, 2002): 1433-1440.
PMID
12050120
Source
pubmed
Published In
Genes & development
Volume
16
Issue
11
Publish Date
2002
Start Page
1433
End Page
1440
DOI
10.1101/gad.981202

Divergent vascular mechanisms downstream of Sry establish the arterial system in the XY gonad.

Although the primitive vasculature is identical in XX and XY genital ridges until 11.5 days postcoitum (dpc), by 12.5 dpc the XY gonad develops a distinct vasculature. This male-specific vasculature, which includes the development of a large coelomic vessel, develops coincident with expression of Sry and formation of testis cords. We show that similar levels of proliferation and vasculogenesis expand the primary vasculature in XX and XY gonads. However, soon after Sry expression begins, the XY gonad recruits a large number of endothelial cells from the adjacent mesonephros, a mechanism totally absent in XX gonads. These migrating cells do not contribute to venous or lymphatic development. Instead, these cells contribute to the arterial system, as indicated by expression of ephrinB2 and by elements of the Notch signaling pathway. This newly formed arterial system establishes a new pattern of blood flow in the XY gonad, which we speculate may have an important role in export of testosterone to masculinize the XY embryo.

Authors
Brennan, J; Karl, J; Capel, B
MLA Citation
Brennan, J, Karl, J, and Capel, B. "Divergent vascular mechanisms downstream of Sry establish the arterial system in the XY gonad." Dev Biol 244.2 (April 15, 2002): 418-428.
PMID
11944948
Source
pubmed
Published In
Developmental Biology
Volume
244
Issue
2
Publish Date
2002
Start Page
418
End Page
428
DOI
10.1006/dbio.2002.0578

Cellular and molecular pathways regulating mammalian sex determination.

In mammals, sex is determined by the presence or absence of a single gene on the Y chromosome, Sry. Sry, a member of the high mobility group family of transcription factors, is required to initiate male-specific pathways and repress female-specific pathways. Expression of Sry in the gonad, beginning at 10.5 days postcoitum, leads to the differentiation of the somatic supporting cell precursors as Sertoli cells. These cells direct the other cells of the gonad into their respective lineages. Currently, no direct targets of Sry are known. A number of cellular pathways initiated by Sry are required for testis development. These include the proliferation of pre-Sertoli cells and commitment to the Sertoli lineage, migration of cells from the adjacent mesonephros, and formation of a male-specific vasculature. Work is underway to identify genes controlling these processes. These genes will then be linked to Sry.

Authors
Tilmann, C; Capel, B
MLA Citation
Tilmann, C, and Capel, B. "Cellular and molecular pathways regulating mammalian sex determination." Recent Prog Horm Res 57 (2002): 1-18. (Review)
PMID
12017538
Source
pubmed
Published In
Recent progress in hormone research
Volume
57
Publish Date
2002
Start Page
1
End Page
18

The battle of the sexes: opposing pathways in sex determination.

In mammals, a primordial gonad forms in XY and XX embryos that develops into a testis or an ovary depending on expression of Sry. Sry induces cell signalling pathways, including proliferation of Sertoli precursors and migration of peritubular myoid and vascular cells from the mesonephros. These events result in increased testis size and testis cord organization. Testis cord formation normally prohibits germ cells from entering meiosis. Ovarian fate is initiated in the absence of Sry, and has been proposed to be dependent upon the presence of meiotic germ cells in the gonad. We have shown that a developmental window exists during which testis development can be experimentally induced in XX gonads. This window closes just prior to the time that germ cells enter meiosis. Based on our work and much work that has preceded it, we suggest that the autonomous entry of germ cells into meiosis initiates the ovarian pathway and blocks testis development. Sry opposes this pathway by initiating testis cord formation prior to meiosis which sequesters germ cells inside cords and arrests them in mitosis. Current experiments in the lab address the hypothesis that cord formation and germ cell entry into meiosis are competing pathways in gonad development.

Authors
Yao, HH-C; Tilmann, C; Zhao, G-Q; Capel, B
MLA Citation
Yao, HH-C, Tilmann, C, Zhao, G-Q, and Capel, B. "The battle of the sexes: opposing pathways in sex determination." Novartis Found Symp 244 (2002): 187-198. (Review)
PMID
11990791
Source
pubmed
Published In
Novartis Foundation Symposium
Volume
244
Publish Date
2002
Start Page
187
End Page
198

Male-to-female sex reversal in mice lacking fibroblast growth factor 9.

Fgfs direct embryogenesis of several organs, including the lung, limb, and anterior pituitary. Here we report male-to-female sex reversal in mice lacking Fibroblast growth factor 9 (Fgf9), demonstrating a novel role for FGF signaling in testicular embryogenesis. Fgf9(-/-) mice also exhibit lung hypoplasia and die at birth. Reproductive system phenotypes range from testicular hypoplasia to complete sex reversal, with most Fgf9(-/-) XY reproductive systems appearing grossly female at birth. Fgf9 appears to act downstream of Sry to stimulate mesenchymal proliferation, mesonephric cell migration, and Sertoli cell differentiation in the embryonic testis. While Sry is found only in some mammals, Fgfs are highly conserved. Thus, Fgfs may function in sex determination and reproductive system development in many species.

Authors
Colvin, JS; Green, RP; Schmahl, J; Capel, B; Ornitz, DM
MLA Citation
Colvin, JS, Green, RP, Schmahl, J, Capel, B, and Ornitz, DM. "Male-to-female sex reversal in mice lacking fibroblast growth factor 9." Cell 104.6 (March 23, 2001): 875-889.
PMID
11290325
Source
pubmed
Published In
Cell
Volume
104
Issue
6
Publish Date
2001
Start Page
875
End Page
889

Defective mesonephric cell migration is associated with abnormal testis cord development in C57BL/6J XY(Mus domesticus) mice.

During the critical period of mouse sex determination, mesenchymal cells migrate from the mesonephros into the adjacent developing testis. This process is thought to initiate cord development and is dependent on Sry. The presence of Sry, however, does not always guarantee normal testis development. For example, transfer of certain Mus domesticus-derived Y chromosomes, i.e., M. domesticus Sry alleles, onto the C57BL/6J (B6) inbred mouse strain results in abnormal testis development. We tested the hypothesis that mesonephric cell migration was impaired in three cases representing a range of aberrant testis development: B6 XY(AKR), B6 XY(POS), and (BXD-21 x B6-Y(POS))F1 XY(POS). In each case, mesonephric cell migration was abnormal. Furthermore, the timing, extent, and position of migrating cells in vitro and cord development in vivo were coincident, supporting the hypothesis that mesonephric cells are critical for cord development. Additional experiments indicated that aberrant testis development results from the inability of Sry(M. domesticus) to initiate normal cell migration, but that downstream signal transduction mechanisms are intact. These experiments provide new insight into the mechanism of C57BL/6J-Y(M. domesticus) sex reversal. We present a model incorporating these findings as they relate to mammalian sex determination.

Authors
Albrecht, KH; Capel, B; Washburn, LL; Eicher, EM
MLA Citation
Albrecht, KH, Capel, B, Washburn, LL, and Eicher, EM. "Defective mesonephric cell migration is associated with abnormal testis cord development in C57BL/6J XY(Mus domesticus) mice." Dev Biol 225.1 (September 1, 2000): 26-36.
PMID
10964462
Source
pubmed
Published In
Developmental Biology
Volume
225
Issue
1
Publish Date
2000
Start Page
26
End Page
36
DOI
10.1006/dbio.2000.9819

The battle of the sexes.

The sex determining gene, Sry, determines the sex of the organism by initiating development of a testis rather than an ovary from the cells of the bipotential gonad. In the 10 years since the discovery of Sry, new genes and cellular pathways that operate in the establishment of the gonadal primordium and the initiation of testis development have been discovered. Experiments defining mechanisms downstream of Sry are providing clear examples of how a regulatory transcription factor initiates cellular processes including proliferation and cell migration, which in turn influence architectural patterning, fate commitment, and differentiation of cells within an organ.

Authors
Capel, B
MLA Citation
Capel, B. "The battle of the sexes." Mech Dev 92.1 (March 15, 2000): 89-103. (Review)
PMID
10704890
Source
pubmed
Published In
Mechanisms of Development
Volume
92
Issue
1
Publish Date
2000
Start Page
89
End Page
103

Sry induces cell proliferation in the mouse gonad.

Sry is the only gene on the Y chromosome that is required for testis formation in mammals. One of the earliest morphological changes that occurs as a result of Sry expression is a size increase of the rudimentary XY gonad relative to the XX gonad. Using 5'-bromo-2'-deoxyuridine (BrdU) incorporation to label dividing cells, we found that the size increase corresponds with a dramatic increase in somatic cell proliferation in XY gonads, which is not detected in XX gonads. This male-specific proliferation was observed initially in the cells of the coelomic epithelium and occurred in two distinct stages. During the first stage, proliferation in the XY gonad was observed largely in SF1-positive cells and contributed to the Sertoli cell population. During the second stage, proliferation was observed in SF1-negative cells at and below the coelomic epithelium and did not give rise to Sertoli cells. Both stages of proliferation were dependent on Sry and independent of any other genetic differences between male and female gonads, such as X chromosome dosage or other genes on the Y chromosome. The increase in cell proliferation began less than 24 hours after the onset of Sry expression, before the establishment of male-specific gene expression patterns, and before the appearance of any other known male-specific morphological changes in the XY gonad. Therefore, an increase in cell proliferation in the male coelomic epithelium is the earliest identified effect of Sry expression.

Authors
Schmahl, J; Eicher, EM; Washburn, LL; Capel, B
MLA Citation
Schmahl, J, Eicher, EM, Washburn, LL, and Capel, B. "Sry induces cell proliferation in the mouse gonad." Development 127.1 (January 2000): 65-73.
PMID
10654601
Source
pubmed
Published In
Development (Cambridge)
Volume
127
Issue
1
Publish Date
2000
Start Page
65
End Page
73

Mesonephric cell migration induces testis cord formation and Sertoli cell differentiation in the mammalian gonad.

In mammals a single gene on the Y chromosome, Sry, controls testis formation. One of the earliest effects of Sry expression is the induction of somatic cell migration from the mesonephros into the XY gonad. Here we show that mesonephric cells are required for cord formation and male-specific gene expression in XY gonads in a stage-specific manner. Culturing XX gonads with an XY gonad at their surface, as a 'sandwich', resulted in cell migration into the XX tissue. Analysis of sandwich gonads revealed that in the presence of migrating cells, XX gonads organized cord structures and acquired male-specific gene expression patterns. From these results, we conclude that mesonephric cell migration plays a critical role in the formation of testis cords and the differentiation of XY versus XX cell types.

Authors
Tilmann, C; Capel, B
MLA Citation
Tilmann, C, and Capel, B. "Mesonephric cell migration induces testis cord formation and Sertoli cell differentiation in the mammalian gonad." Development 126.13 (July 1999): 2883-2890.
PMID
10357932
Source
pubmed
Published In
Development (Cambridge)
Volume
126
Issue
13
Publish Date
1999
Start Page
2883
End Page
2890

Migration of mesonephric cells into the mammalian gonad depends on Sry.

In mammals, the primary step in male sex determination is the initiation of testis development which depends on the expression of the Y-linked testis determining gene, Sry. The mechanisms by which Sry controls this process are unknown. Studies showed that cell migration from the adjacent mesonephros only occurs into XY gonads; however, it was not known whether this effect depended on Sry, another Y-linked gene, or the presence of one versus two X chromosomes. Here we provide genetic proof that Sry is the only Y-linked gene necessary for cell migration into the gonad. Cell migration from the mesonephros into the differentiating gonad is consistently associated with Sty's presence and with testis cord formation, suggesting that cell migration plays a critical role in the initiation of testis cord development. The induction of cell migration represents the earliest signaling pathway yet assigned to Sry.

Authors
Capel, B; Albrecht, KH; Washburn, LL; Eicher, EM
MLA Citation
Capel, B, Albrecht, KH, Washburn, LL, and Eicher, EM. "Migration of mesonephric cells into the mammalian gonad depends on Sry." Mech Dev 84.1-2 (June 1999): 127-131.
PMID
10473126
Source
pubmed
Published In
Mechanisms of Development
Volume
84
Issue
1-2
Publish Date
1999
Start Page
127
End Page
131

Sertoli cells of the mouse testis originate from the coelomic epithelium.

During mouse development, the gonad begins to form shortly before 10. 5 days postcoitum (dpc) on the ventromedial side of the mesonephros. The XY gonad consists of germ cells and somatic cells. The origin of the germ cells is clearly established; however, the origin of the somatic cells, especially the epithelial supporting cell lineages, called Sertoli cells, is still unclear. Sertoli cells are the first somatic cell type to differentiate in the testis and are thought to express Sry, the male sex-determining gene, and to play a crucial role in directing testis development. Previous data have suggested that the somatic cells of the gonad may arise from the mesonephric tubules, the mesonephric mesenchyme, or the coelomic epithelium. Immunohistochemical staining of the gonad at 11.5 dpc showed that the basement membrane barrier under the coelomic epithelium is discontinuous, suggesting that cells in the coelomic epithelium at this stage might move inward. To test this possibility directly, cells of the coelomic epithelium were labeled using the fluorescent lipophilic dye, DiI. We show that when labeled at tail somite 15-17 stages, corresponding to 11.2-11.4 dpc, the coelomic epithelial cells of both sexes migrated into the gonad. In XY gonads, the migrating coelomic epithelial cells became Sertoli cells, as well as interstitial cells. This ability of the coelomic epithelium to give rise to Sertoli cells was developmentally regulated. When labeled at tail somite 18-20 stages, corresponding to 11.5-11.7 dpc, the coelomic epithelial cells no longer became Sertoli cells. Instead, cells that migrated into the gonad stayed outside testis cords, in the interstitium. Migration gradually decreased and ceased by tail somite 30 stage, corresponding to 12.5 dpc, after testis cords had formed and the basement membrane layer underlying the coelomic epithelium had thickened to form the tunica albuginea. In XX gonads, coelomic epithelial cells also migrated into the gonad, but there was no obvious fate restriction during the same developmental period. Taken together, our data show that the coelomic epithelium is a source of Sertoli cells as well as other somatic cells of the gonad in the developing mouse testis.

Authors
Karl, J; Capel, B
MLA Citation
Karl, J, and Capel, B. "Sertoli cells of the mouse testis originate from the coelomic epithelium." Dev Biol 203.2 (November 15, 1998): 323-333.
PMID
9808783
Source
pubmed
Published In
Developmental Biology
Volume
203
Issue
2
Publish Date
1998
Start Page
323
End Page
333
DOI
10.1006/dbio.1998.9068

Sry and the testis: molecular pathways of organogenesis.

The gene Sry acts as a switch, initiating pathways leading to the differentiation of a testis rather than an ovary from the indifferent gonad (genital ridge) in mammals. The early events following Sry expression include rapid changes in the topographical organization of cells in the XY gonad. Sry must therefore initiate signaling pathways that direct male-specific patterns of proliferation, migration, cell-cell organization, and vascularization. We have identified an increase in male-specific proliferation by 12.0 days post coitum, while proliferation in the female gonad declines. We have also observed male-specific cell migration from the mesonephros into the gonad in a composite organ culture system in which gonads from wild-type mice (CD1) and mesonephroi from a transgenic strain expressing beta-galactosidase in all its cells (ROSA26) were grafted together in vitro at the indifferent stage of gonadogenesis. Migration depends on an active signal that requires the presence of a Y chromosome in the gonadal portion of the graft. The signals that trigger migration operate over considerable distances, suggesting either a long-range diffusible factor or the involvement of a rapid and efficient relay mechanism. Identification of the somatic cells contributed from the mesonephros with cell-specific markers indicated that some of the migrating cells were endothelial, revealing differences in processes of vascularization between male and female gonads. A second distinct population of migrating cells lay in close apposition to endothelial cells, and a third population occupied positions circumscribing areas of condensing Sertoli cells.

Authors
Brennan, J; Karl, J; Martineau, J; Nordqvist, K; Schmahl, J; Tilmann, C; Ung, K; Capel, B
MLA Citation
Brennan, J, Karl, J, Martineau, J, Nordqvist, K, Schmahl, J, Tilmann, C, Ung, K, and Capel, B. "Sry and the testis: molecular pathways of organogenesis." J Exp Zool 281.5 (August 1, 1998): 494-500.
PMID
9662836
Source
pubmed
Published In
Journal of Experimental Zoology
Volume
281
Issue
5
Publish Date
1998
Start Page
494
End Page
500

Sex in the 90s: SRY and the switch to the male pathway.

In mammals the male sex determination switch is controlled by a single gene on the Y chromosome, SRY. SRY encodes a protein with an HMG-like DNA-binding domain, which probably acts as a local organizer of chromatin structure. It is believed to regulate downstream genes in the sex determination cascade, although no direct targets of SRY are clearly known. More genes in the pathway have been isolated through mutation approaches in mouse and human. At least three genes, SRY itself, SOX9, and DAX1, are dosage sensitive, providing molecular evidence that the sex determination step operates at a critical threshold. SRY initiates development of a testis from the bipotential cells of the early gonad. The dimorphic male and female pathways present a rare opportunity to link a pivotal gene in development with morphogenetic mechanisms that operate to pattern an organ and the differentiation of its cells. Mechanisms of testis organogenesis triggered downstream of SRY include pathways of cell signaling controlling cell reorganization, cell proliferation, cell migration, and vascularization.

Authors
Capel, B
MLA Citation
Capel, B. "Sex in the 90s: SRY and the switch to the male pathway." Annu Rev Physiol 60 (1998): 497-523. (Review)
PMID
9558474
Source
pubmed
Published In
Annual Review of Physiology
Volume
60
Publish Date
1998
Start Page
497
End Page
523
DOI
10.1146/annurev.physiol.60.1.497

Male-specific cell migration into the developing gonad.

BACKGROUND: The gene Sry acts as a developmental switch, initiating a pathway of gene activity that leads to the differentiation of testis rather than ovary from the indifferent gonad (genital ridge) in mammalian embryos. The early events following Sry expression include rapid changes in the topographical organization of cells in the XY gonad. To investigate the contribution of mesonephric cells to this process, gonads from wild-type mice (CD1), and mesonephroi from a transgenic strain ubiquitously expressing beta-galactosidase (ROSA26), were grafted together in vitro. After culture, organs were fixed and stained for beta-galactosidase activity to identify cells contributed from the mesonephros to the male or female gonad. RESULTS: Migration of mesonephric cells occurred into XY but not XX gonads from 11.5-16.5 days post coitum (dpc). Somatic cells contributed from the mesonephros were distinguished by their histological location and by available cell-specific markers. Some of the migrating cells were endothelial; a second population occupied positions circumscribing areas of condensing Sertoli cells; and a third population lay in close apposition to endothelial cells. CONCLUSIONS: OFFgration from the mesonephros to the gonad is male specific at this stage of development and depends on an active signal that requires the presence of a Y chromosome in the gonad. The signals that trigger migration operate over considerable distances and behave as chemoattractants. We suggest that migration of cells into the bipotential gonad may have a critical role in initiating the divergence of development towards the testis pathway.

Authors
Martineau, J; Nordqvist, K; Tilmann, C; Lovell-Badge, R; Capel, B
MLA Citation
Martineau, J, Nordqvist, K, Tilmann, C, Lovell-Badge, R, and Capel, B. "Male-specific cell migration into the developing gonad." Curr Biol 7.12 (December 1, 1997): 958-968.
PMID
9382843
Source
pubmed
Published In
Current Biology
Volume
7
Issue
12
Publish Date
1997
Start Page
958
End Page
968

Establishment and characterization of conditionally immortalized cells from the mouse urogenital ridge.

Cell cultures from the urogenital ridge have been established to facilitate the study of the regulation and downstream interactions of Sry in mammalian sex determination. Cells have been explanted from transgenic mice carrying a temperature sensitive SV40 large T-antigen, and established in ongoing cultures. Analysis of the cells in these cultures at the electron microscope level reveals multiple cell types that compare to the cell types found in vivo during this period of development. Primordial germ cells, that are simultaneously explanted in the course of these experiments, also survive in culture. The explants undergo a morphogenetic organization into branching cord-like structures when cells are trypsinized and plated in extracellular matrix (Matrigel). We analyzed the expression of a number of molecular markers of the fetal gonad during monolayer culture, during in vitro morphogenesis in Matrigel, and in clonal lines derived from the complex explants. This analysis included Sry which is found to be expressed in some cultures from XY urogenital ridges that have been maintained for as long as 8 months.

Authors
Capel, B; Hawkins, JR; Hirst, E; Kioussis, D; Lovell-Badge, R
MLA Citation
Capel, B, Hawkins, JR, Hirst, E, Kioussis, D, and Lovell-Badge, R. "Establishment and characterization of conditionally immortalized cells from the mouse urogenital ridge." J Cell Sci 109 ( Pt 5) (May 1996): 899-909.
PMID
8743937
Source
pubmed
Published In
Journal of cell science
Volume
109 ( Pt 5)
Publish Date
1996
Start Page
899
End Page
909

The role of Sry in cellular events underlying mammalian sex determination.

Authors
Capel, B
MLA Citation
Capel, B. "The role of Sry in cellular events underlying mammalian sex determination." Curr Top Dev Biol 32 (1996): 1-37. (Review)
PMID
8929664
Source
pubmed
Published In
Current topics in developmental biology
Volume
32
Publish Date
1996
Start Page
1
End Page
37

Three-dimensional structure of the developing mouse genital ridge.

We are interested in understanding how the field of cells which forms the gonad arises, and how the testis-determining gene, Sry, controls morphogenesis of a testis within this field of cells. To appreciate changes in the three-dimensional structure of the mouse genital ridge at this time in development, whole-mount genital ridges taken from male and female embryos over the developmental period when the initiation of testis cord morphogenesis takes place, were stained with an antibody against laminin. Samples were visualized using confocal microscopy. Anti-laminin illuminates the elaborate array of mesonephric duct and tubules which occupy the cranial two-thirds of the mesonephros at the earliest timepoint. This complex structure gradually regresses as testis cords form in male gonads. No structural organisation is recognized by this antibody in the female gonadal region during this period. Confocal sections in the Z-plane reveal continuous cellular connections between 3-6 mesonephric tubules and the gonadal primordium. These cellular bridges are present in male and female gonads, so they do not depend on the expression of Sry. We consider the possibility that these bridges constitute the pathways of the founder cells of the gonadal primordium.

Authors
Karl, J; Capel, B
MLA Citation
Karl, J, and Capel, B. "Three-dimensional structure of the developing mouse genital ridge." Philos Trans R Soc Lond B Biol Sci 350.1333 (November 29, 1995): 235-242.
PMID
8570687
Source
pubmed
Published In
Philosophical Transactions B
Volume
350
Issue
1333
Publish Date
1995
Start Page
235
End Page
242
DOI
10.1098/rstb.1995.0157

Expression of Sry, the mouse sex determining gene.

In the mouse, Sry is expressed by germ cells in the adult testis and by somatic cells in the genital ridge. Transcripts in the former exist as circular RNA molecules of 1.23 kb, which are unlikely to be efficiently translated. We have used RNase protection to map the extent of the less abundant Sry transcript in the developing gonad. We demonstrate that it is a linear mRNA derived from a single exon. This begins in the unique region 5' of the protein coding region and extends several kilobases into the 3' arm of the large inverted repeat which bounds the Sry genomic locus. Knowledge of this transcript, which is very different from that of the human SRY gene, allows us to predict its protein product and reveals several features which may be involved in translational control. Our data is also consistent with there being two promoters for the Sry gene, a proximal one that gives functional transcripts in the genital ridge and a distal promoter used in germ cells in the adult testis. As RNase protection is a quantitative technique, a detailed timecourse of Sry expression was carried out using accurately staged samples. Sry transcripts are first detectable just after 10.5 days post coitum, they reach a peak at 11.5 days and then decline sharply so that none are detected 24 hours later. This was compared with anti-Müllerian hormone gene expression, an early marker of Sertoli cells and the first known downstream gene of Sry. Amh expression begins 20 hours after the onset of Sry expression at a time when Sry transcripts are at their peak. While this result does not prove a direct interaction between the two genes, it defines the critical period during which Sry must act to initiate Sertoli cell differentiation.

Authors
Hacker, A; Capel, B; Goodfellow, P; Lovell-Badge, R
MLA Citation
Hacker, A, Capel, B, Goodfellow, P, and Lovell-Badge, R. "Expression of Sry, the mouse sex determining gene." Development 121.6 (June 1995): 1603-1614.
PMID
7600978
Source
pubmed
Published In
Development (Cambridge)
Volume
121
Issue
6
Publish Date
1995
Start Page
1603
End Page
1614

New bedfellows in the mammalian sex-determination affair.

Authors
Capel, B
MLA Citation
Capel, B. "New bedfellows in the mammalian sex-determination affair." Trends Genet 11.5 (May 1995): 161-163. (Review)
PMID
7785069
Source
pubmed
Published In
Trends in Genetics
Volume
11
Issue
5
Publish Date
1995
Start Page
161
End Page
163
DOI
10.1016/S0168-9525(00)89031-9

Y353/B: a candidate multiple-copy spermiogenesis gene on the mouse Y chromosome.

There is evidence from Y Chromosome (Chr) deletion mapping that there is a gene on the long arm of the mouse Y Chr that is needed for the normal development of the sperm head. Since mice with partial Y long arm deletions show incomplete penetrance of the sperm head defect, whereas mice with no Y long arm show complete penetrance, it has been suggested that the 'spermiogenesis' gene may be present in multiple copies. A Y-specific genomic DNA sequence (Y353/B) has previously been described that is present in multiple copies on the long arm of the mouse Y and identifies testis-specific transcripts. We have suggested that Y353/B could be the proposed multiple copy 'spermiogenesis' gene. In support of this suggestion, we show here that mice with a partial Y long arm deletion associated with a 3.5-fold increase in the frequency of abnormal sperm heads have a marked reduction in genomic Y353/B copies and a corresponding reduction in Y353/B-related transcripts. Thus, the incompletely penetrant phenotype correlates with a reduction in Y353/B-related transcription. Furthermore, by in situ hybridization with a Y353/B riboprobe to testis sections, we show that the Y353/B-related transcripts are confined to the round spermatid stage of spermiogenesis, just prior to the shaping of the sperm head. The transcripts sediment with the fraction of cytoplasmic RNA in adult testis that is loaded on polysomes, suggesting that the transcripts are actively translated.

Authors
Conway, SJ; Mahadevaiah, SK; Darling, SM; Capel, B; Rattigan, AM; Burgoyne, PS
MLA Citation
Conway, SJ, Mahadevaiah, SK, Darling, SM, Capel, B, Rattigan, AM, and Burgoyne, PS. "Y353/B: a candidate multiple-copy spermiogenesis gene on the mouse Y chromosome." Mamm Genome 5.4 (April 1994): 203-210.
PMID
7516747
Source
pubmed
Published In
Mammalian Genome
Volume
5
Issue
4
Publish Date
1994
Start Page
203
End Page
210

Deletion of Y chromosome sequences located outside the testis determining region can cause XY female sex reversal.

An approach designed to map and generate mutations in the region of the short arm of the mouse Y chromosome, known to be involved in sex determination and spermatogenesis, is described. This relies on homologous Yp-Sxra pairing and asymmetrical exchange which can occur at meiosis in XY males carrying Sxra on their X chromosome. Such exchange potentially generates deficiencies and duplications of Yp or Sxra. Three fertile XY females were found out of about 450 XY offspring from XSxra/Y x XX crosses. In all three, despite evidence for deletion of Y chromosomal material, the Sry locus was intact. Each deletion involved a repeat sequence, Sx1, located at a distance from Sry. Since expression of Sry was affected these results suggest that long range position effects have disrupted Sry action.

Authors
Capel, B; Rasberry, C; Dyson, J; Bishop, CE; Simpson, E; Vivian, N; Lovell-Badge, R; Rastan, S; Cattanach, BM
MLA Citation
Capel, B, Rasberry, C, Dyson, J, Bishop, CE, Simpson, E, Vivian, N, Lovell-Badge, R, Rastan, S, and Cattanach, BM. "Deletion of Y chromosome sequences located outside the testis determining region can cause XY female sex reversal." Nat Genet 5.3 (November 1993): 301-307.
PMID
8275095
Source
pubmed
Published In
Nature Genetics
Volume
5
Issue
3
Publish Date
1993
Start Page
301
End Page
307
DOI
10.1038/ng1193-301

Circular transcripts of the testis-determining gene Sry in adult mouse testis.

Sry is expressed at higher levels in the adult testis, where no function has been determined, than in the genital ridge, its critical site of action. cDNA and 5' RACE clones isolated from testis or from Sry-transfected cell lines have an unusual structure, with 3' sequences located in a 5' position. RNAase protection assays and reverse transcription polymerase chain reactions confirmed that these unusual RNA molecules represent the most abundant transcript in testis. Furthermore, oligonucleotide hybridization and RNAase H digestion proved that these Sry RNA molecules are circular. Similar transcripts were detected in the testes of mice with Mus musculus musculus, Mus musculus domesticus, and Mus spretus Sry genes. The circular RNA is found in the cytoplasm but is not substantially bound to polysomes. We suggest that the circles arise from normal splicing processes as a consequence of the unusual genomic structure surrounding the Sry locus in the mouse.

Authors
Capel, B; Swain, A; Nicolis, S; Hacker, A; Walter, M; Koopman, P; Goodfellow, P; Lovell-Badge, R
MLA Citation
Capel, B, Swain, A, Nicolis, S, Hacker, A, Walter, M, Koopman, P, Goodfellow, P, and Lovell-Badge, R. "Circular transcripts of the testis-determining gene Sry in adult mouse testis." Cell 73.5 (June 4, 1993): 1019-1030.
PMID
7684656
Source
pubmed
Published In
Cell
Volume
73
Issue
5
Publish Date
1993
Start Page
1019
End Page
1030

The sry gene and sex determination in mammals

With the isolation and characterization of Sry, a gene with a critical role in development has been defined. Sry can be described as a master regulatory gene in that it has a pivotal role in the sex determination pathway. However, much work must be done to discover how the gene fits into such a pathway, both at the level of molecular cascades and their integration with morphogenic events during organogenesis. First, the precise pattern of expression of Sry suggests that it must be regulated by tissue-specific transcription factors, or a unique combination of factors present within the supporting cell precursor lineage. These factors are clearly not sex-specific. Second, there are likely to be gene products that interact with the Sry protein and contribute to the specificity of its interaction with target genes. Third, the downstream target genes need to be defined. Sry must initiate (or repress) the expression of some critical genes. Sry appears to act only for a very brief period just before testis cord formation; therefore, it is not required for any long-term maintenance of gene activity. How does the expression of Sry lead to the changes in cellular properties which result in organization into testis cords? Determining the nature of the interaction of Sry with DNA, and the definition of target genes will clearly be required before the role of Sry in sex determination can be understood at the cellular and molecular levels.

Authors
Capel, B; Lovell-Badge, R
MLA Citation
Capel, B, and Lovell-Badge, R. "The sry gene and sex determination in mammals." Advances in Developmental Biology (1992) 2.C (1993): 1-35.
Source
scival
Published In
Advances in Developmental Biology (1992)
Volume
2
Issue
C
Publish Date
1993
Start Page
1
End Page
35

Expression of a candidate sex-determining gene during mouse testis differentiation.

The development of a eutherian mammal as a male is a consequence of testis formation in the embryo, which is thought to be initiated by a gene on the Y chromosome. In the absence of this gene, ovaries are formed and female characteristics develop. Sex determination therefore hinges on the action of this testis-determining gene, known as Tdy in mice and TDF in humans. In the past, several genes proposed as candidates for Tdy/TDF have subsequently been dismissed on the grounds of inappropriate location or expression. We have recently described a candidate for Tdy, which maps to the minimum sex-determining region of the mouse Y chromosome. To examine further the involvement of this gene, Sry, in testis development, we have studied its expression in detail. Fetal expression of Sry is limited to the period in which testes begin to form. This expression is confined to gonadal tissue and does not require the presence of germ cells. Our observations strongly support a primary role for Sry in mouse sex determination.

Authors
Koopman, P; Münsterberg, A; Capel, B; Vivian, N; Lovell-Badge, R
MLA Citation
Koopman, P, Münsterberg, A, Capel, B, Vivian, N, and Lovell-Badge, R. "Expression of a candidate sex-determining gene during mouse testis differentiation." Nature 348.6300 (November 29, 1990): 450-452.
PMID
2247150
Source
pubmed
Published In
Nature
Volume
348
Issue
6300
Publish Date
1990
Start Page
450
End Page
452
DOI
10.1038/348450a0

A gene mapping to the sex-determining region of the mouse Y chromosome is a member of a novel family of embryonically expressed genes.

A gene mapping to the sex-determining region of the mouse Y chromosome is deleted in a line of XY female mice mutant for Tdy, and is expressed at a stage during male gonadal development consistent with its having a role in testis determination. This gene is a member of a new family of at least five mouse genes, related by an amino-acid motif showing homology to other known or putative DNA-binding domains.

Authors
Gubbay, J; Collignon, J; Koopman, P; Capel, B; Economou, A; Münsterberg, A; Vivian, N; Goodfellow, P; Lovell-Badge, R
MLA Citation
Gubbay, J, Collignon, J, Koopman, P, Capel, B, Economou, A, Münsterberg, A, Vivian, N, Goodfellow, P, and Lovell-Badge, R. "A gene mapping to the sex-determining region of the mouse Y chromosome is a member of a novel family of embryonically expressed genes." Nature 346.6281 (July 19, 1990): 245-250.
PMID
2374589
Source
pubmed
Published In
Nature
Volume
346
Issue
6281
Publish Date
1990
Start Page
245
End Page
250
DOI
10.1038/346245a0

Long- and short-lived murine hematopoietic stem cell clones individually identified with retroviral integration markers.

The proliferative longevity of totipotent hematopoietic stem cells (THSC) is a limiting factor in normal hematopoiesis and in therapy by cell- or gene-replacement, but has not yet been ascertained. We have followed the long-term fate of individual clones of mouse THSC from fetal liver or adult bone marrow, after labeling in culture, followed by engraftment and serial transplantation in unirradiated W/Wv-C57BL/6 hosts. The ancestor cell of each clone and its mitotic progeny were uniquely identifiable retrospectively by the DNA integration pattern experimentally produced by replication-incompetent recombinant murine retroviruses. These viruses provided physiologically neutral markers. The marked clones proved to be derived from THSC, based on their contributions to a wide array of myeloid and lymphoid blood lineages in the hosts. The label also identified the target cells as the population displaying clonal succession. The various labeled stem cell clones proliferated for substantially different periods of time. The longest observed clone endured, after the original cell was marked, for at least 2 1/2 years--the equivalent of a mouse's lifetime. However, the results suggest that THSC clones are not all long-lived and that even the longest-lived ones may not be potentially immortal. Thus, the unpredictable lifespan of any given THSC clone indicates the desirability of introducing multiple clones in therapeutic transplants.

Authors
Capel, B; Hawley, RG; Mintz, B
MLA Citation
Capel, B, Hawley, RG, and Mintz, B. "Long- and short-lived murine hematopoietic stem cell clones individually identified with retroviral integration markers." Blood 75.12 (June 15, 1990): 2267-2270.
PMID
2350573
Source
pubmed
Published In
Blood
Volume
75
Issue
12
Publish Date
1990
Start Page
2267
End Page
2270

Neonatal W-mutant mice are favorable hosts for tracking development of marked hematopoietic stem cells.

Neonatal unirradiated mice of W-mutant genotypes, with a hematopoietic stem cell defect and anemia, were injected i.v. with normal fetal liver hematopoietic cells. Efficient, long-term engraftment occurred as a result of the competitive advantage to the donor stem cells. The frequency of engraftment and rate of repopulation characteristically diminish in the series W/Wv, Wf/Wf, and Wv/+, in which the severity of the endogenous defect is progressively less. H-2 compatibility is required in the inbred strain combinations examined; other histocompatibility loci play a minor role in some strain combinations. Engraftment is due to self-renewing hematopoietic stem cells ancestral to myeloid and lymphoid lineages. The more mildly defective mutants display much greater variability in the kinetics of repopulation--a result consistent with seeding by single, or very few, stem cells that form developing clones. Engraftment efficiency is reduced by prolonged culture of fetal liver cells during experimental infection by recombinant retroviruses; nevertheless, after 24 h in vitro to achieve retroviral marking, stem cells retain their ability to repopulate and develop in W/Wv neonates.

Authors
Capel, B; Mintz, B
MLA Citation
Capel, B, and Mintz, B. "Neonatal W-mutant mice are favorable hosts for tracking development of marked hematopoietic stem cells." Exp Hematol 17.8 (September 1989): 872-876.
PMID
2569983
Source
pubmed
Published In
Experimental Hematology
Volume
17
Issue
8
Publish Date
1989
Start Page
872
End Page
876

Clonal contributions of small numbers of retrovirally marked hematopoietic stem cells engrafted in unirradiated neonatal W/Wv mice.

Mice were repopulated with small numbers of retrovirally marked hematopoietic cells operationally definable as totipotent hematopoietic stem cells, without engraftment of cells at later stages of hematopoiesis, in order to facilitate analysis of stem cell clonal histories. This result depended upon the use of unirradiated W/Wv newborn recipients. Before transplantation, viral integration markers were introduced during cocultivation of fetal liver or bone marrow cells with helper cell lines exporting defective recombinant murine retroviruses of the HHAM series. Omission of selection in culture [although the vector contained the bacterial neomycin-resistance (neo) gene] also limited the proportion of stem cells that were virally labeled. Under these conditions, engraftment was restricted to a small population of marked and unmarked normal donor stem cells, due to their competitive advantage over the corresponding defective cells of the mutant hosts. A relatively simple and coherent pattern emerged, of one or a few virally marked clones, in contrast to previous studies. In order to establish the totipotent hematopoietic stem cell identity of the engrafted cells, tissues were sampled for viral and inbred-strain markers for periods close to one year after transplantation. The virally labeled clones were characterized as stem cell clones by their extensive self-renewal and by formation of the wide range of myeloid and lymphoid lineages tested. Results clearly documented concurrent contributions of cohorts of stem cells to hematopoiesis. A given stem cell can increase or decrease its proliferative activity, become completely inactive or lost, or become active after a long latent period. The contribution of a single clone present in a particular lineage was usually between 5% and 20%.

Authors
Capel, B; Hawley, R; Covarrubias, L; Hawley, T; Mintz, B
MLA Citation
Capel, B, Hawley, R, Covarrubias, L, Hawley, T, and Mintz, B. "Clonal contributions of small numbers of retrovirally marked hematopoietic stem cells engrafted in unirradiated neonatal W/Wv mice." Proc Natl Acad Sci U S A 86.12 (June 1989): 4564-4568.
PMID
2567516
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
86
Issue
12
Publish Date
1989
Start Page
4564
End Page
4568

Complete and N-terminal amino-acid sequences of CNBr-peptides CB5 and CB3 from diphteria toxin fragment B [proceedings].

Authors
Falmagne, P; Capiau, C; Capel, B; Lambotte, P; Dirkx, J
MLA Citation
Falmagne, P, Capiau, C, Capel, B, Lambotte, P, and Dirkx, J. "Complete and N-terminal amino-acid sequences of CNBr-peptides CB5 and CB3 from diphteria toxin fragment B [proceedings]." Arch Int Physiol Biochim 87.4 (October 1979): 812-813.
PMID
93919
Source
pubmed
Published In
Archives Internationales de Physiologie et de Biochimie
Volume
87
Issue
4
Publish Date
1979
Start Page
812
End Page
813
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