You are here

Silver, Debra Lynn

Overview:

Our laboratory studies embryonic brain development, focusing on the process of neurogenesis.  During neurogenesis of the cerebral cortex, neural progenitors produce neurons.  This process helps dictate the size, structure, and function of the adult brain. Moreover, aberrant neurogenesis can cause neurodevelopmental disorders such as microcephaly (reduced brain size associated with intellectual disability) and autism spectrum disorder. Despite the fundamental clinical relevance of neurogenesis, the mechanisms controlling this process remain poorly understood. Our goal is to help fill this void by elucidating genetic and cellular regulation of neural progenitors in the developing brain.


A major research direction of our lab is to understand mechanisms controlling brain size. We are especially interested in how post-transcriptional regulation influences dynamic neural progenitor behavior and function.  The RNA binding proteins studied are associated with neurodevelopmental pathologies including brain malformations.  A second focus of our research is to understand how regulatory sequences, termed enhancers, contribute to unique features of the human brain by modulating neural progenitor proliferation. The lab employs a repertoire of genetic and cell biological tools including mouse genetics, ex vivo and in vitro live imaging, genomics, and proteomics. Using multidisciplinary approaches give us mechanistic insights at molecular, cellular, and tissue levels.  Our long-term objective is to help broaden our fundamental understanding of how the brain is built, how stem cells behave, and the etiology of developmental diseases.

Positions:

Assistant Professor in Molecular Genetics and Microbiology

Molecular Genetics and Microbiology
School of Medicine

Assistant Professor in Cell Biology

Cell Biology
School of Medicine

Assistant Professor of Neurobiology

Neurobiology
School of Medicine

Investigator in the Duke Institute for Brain Sciences

Duke Institute for Brain Sciences
Institutes and Provost's Academic Units

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

B.S. 1993

B.S. — Tufts University

Ph.D. 2003

Ph.D. — Johns Hopkins University

News:

Grants:

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

Amelioration of neural stem cell defects underlying Zika virus induced microcephaly

Administered By
Molecular Genetics and Microbiology
AwardedBy
Hartwell Foundation
Role
Principal Investigator
Start Date
April 01, 2017
End Date
March 31, 2020

RNA localization in neural stem cells during cortical development

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2016
End Date
June 30, 2019

Post-transcriptional RNA regulation in mammalian neural stem cells

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
April 01, 2017
End Date
March 31, 2019

Zika virus infection of neural stem cells to model pathogen-induced microcephaly

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
September 30, 2016
End Date
August 31, 2018

Mechanisms of neural progenitor division in the developing brain

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
June 01, 2013
End Date
May 31, 2018

Dissecting the role of the exon junction complex in embryonic corticogenesis

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
April 01, 2016
End Date
March 31, 2018

Training Program in Developmental and Stem Cell Biology

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

Basic predoctoral training in neuroscience

Administered By
Neurobiology
AwardedBy
National Institutes of Health
Role
Training Faculty
Start Date
July 01, 1992
End Date
June 30, 2017

Serial Block Face Scanning Electron Microscope

Administered By
Pathology
AwardedBy
National Institutes of Health
Role
Major User
Start Date
June 01, 2016
End Date
May 31, 2017

Analysis of the Exon Junction Complex in Neural Development and Microcephaly

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
December 01, 2008
End Date
November 30, 2013
Show More

Publications:

EIF4A3 deficient human iPSCs and mouse models demonstrate neural crest defects that underlie Richieri-Costa-Pereira Syndrome.

Biallelic loss-of-function mutations in the RNA binding protein EIF4A3 cause Richieri-Costa-Pereira syndrome (RCPS), an autosomal recessive condition mainly characterized by craniofacial and limb malformations. However, the pathogenic cellular mechanisms responsible for this syndrome are entirely unknown. Here we used two complementary approaches, patient-derived induced pluripotent stem cells (iPSCs) and conditional Eif4a3 mouse models, to demonstrate that defective Neural Crest Cell (NCC) development explains RCPS craniofacial abnormalities. RCPS iNCCs have decreased migratory capacity, a distinct phenotype relative to other craniofacial disorders. Eif4a3 haploinsufficient embryos presented altered mandibular process fusion and micrognathia, thus recapitulating the most penetrant phenotypes of the syndrome. These defects were evident in either ubiquitous or NCC-specific Eif4a3 haploinsufficient animals, demonstrating an autonomous requirement of Eif4a3 in NCCs. Notably, RCPS NCC-derived mesenchymal cells (nMSCs) showed premature bone differentiation, a phenotype paralleled by premature clavicle ossification in Eif4a3 haploinsufficient embryos. Likewise, nMSCs presented compromised in vitro chondrogenesis, and Meckeĺs cartilage was underdeveloped in vivo. These findings indicate novel and essential requirements of EIF4A3 for NCC migration and osteochondrogenic differentiation during craniofacial development. Altogether, complementary use of iPSCs and mouse models pinpoint unique cellular mechanisms by which EIF4A3 mutation causes RCPS, and provide a paradigm to study craniofacial disorders.

Authors
Miller, EE; Kobayashi, GS; Musso, CM; Allen, M; Ishiy, FAA; de Caires Junior, LC; Guimarães, ESG; Griesi-Oliveira, K; Zechi-Ceide, RM; Richieri-Costa, A; Bertola, DR; Passos-Bueno, MR; Silver, DL
MLA Citation
Miller, EE, Kobayashi, GS, Musso, CM, Allen, M, Ishiy, FAA, de Caires Junior, LC, Guimarães, ESG, Griesi-Oliveira, K, Zechi-Ceide, RM, Richieri-Costa, A, Bertola, DR, Passos-Bueno, MR, and Silver, DL. "EIF4A3 deficient human iPSCs and mouse models demonstrate neural crest defects that underlie Richieri-Costa-Pereira Syndrome." Human molecular genetics (March 2, 2017).
PMID
28334780
Source
epmc
Published In
Human Molecular Genetics
Publish Date
2017
DOI
10.1093/hmg/ddx078

Mouse models of Casc3 reveal developmental functions distinct from other components of the exon junction complex.

The exon junction complex (EJC) is a multiprotein complex integral to mRNA metabolism. Biochemistry and genetic studies have concluded that the EJC is composed of four core proteins, MAGOH, EIF4A3, RBM8A, and CASC3. Yet recent studies in Drosophila indicate divergent physiological functions for Barentsz, the mammalian Casc3 ortholog, raising the question as to whether CASC3 is a constitutive component of the EJC. This issue remains poorly understood, particularly in an in vivo mammalian context. We previously found that haploinsufficiency for Magoh, Eif4a3, or Rbm8a disrupts neuronal viability and neural progenitor proliferation, resulting in severe microcephaly. Here, we use two new Casc3 mouse alleles to demonstrate developmental phenotypes that sharply contrast those of other core EJC components. Homozygosity for either null or hypomorphic Casc3 alleles led to embryonic and perinatal lethality, respectively. Compound embryos lacking Casc3 expression were smaller with proportionately reduced brain size. Mutant brains contained fewer neurons and progenitors, but no apoptosis, all phenotypes explained by developmental delay. This finding, which contrasts with severe neural phenotypes evident in other EJC mutants, indicates Casc3 is largely dispensable for brain development. In the developing brain, CASC3 protein expression is substoichiometric relative to MAGOH, EIF4A3, and RBM8A. Taken together, this argues that CASC3 is not an essential EJC component in brain development and suggests it could function in a tissue-specific manner.

Authors
Mao, H; Brown, HE; Silver, DL
MLA Citation
Mao, H, Brown, HE, and Silver, DL. "Mouse models of Casc3 reveal developmental functions distinct from other components of the exon junction complex." RNA (New York, N.Y.) 23.1 (January 2017): 23-31.
PMID
27780844
Source
epmc
Published In
RNA (New York, N.Y.)
Volume
23
Issue
1
Publish Date
2017
Start Page
23
End Page
31
DOI
10.1261/rna.058826.116

The exon junction complex in neural development and neurodevelopmental disease.

Post-transcriptional mRNA metabolism has emerged as a critical regulatory nexus in proper development and function of the nervous system. In particular, recent studies highlight roles for the exon junction complex (EJC) in neurodevelopment. The EJC is an RNA binding complex composed of 3 core proteins, EIF4A3 (DDX48), RBM8A (Y14), and MAGOH, and is a major hub of post-transcriptional regulation. Following deposition onto mRNA, the EJC serves as a platform for the binding of peripheral factors which together regulate splicing, nonsense mediated decay, translation, and RNA localization. While fundamental molecular roles of the EJC have been well established, the in vivo relevance in mammals has only recently been examined. New genetic models and cellular assays have revealed core and peripheral EJC components play critical roles in brain development, stem cell function, neuronal outgrowth, and neuronal activity. Moreover, human genetics studies increasingly implicate EJC components in the etiology of neurodevelopmental disorders. Collectively, these findings indicate that proper dosage of EJC components is necessary for diverse aspects of neuronal development and function. Going forward, genetic models of EJC components will provide valuable tools for further elucidating functions in the nervous system relevant for neurodevelopmental disease.

Authors
McMahon, JJ; Miller, EE; Silver, DL
MLA Citation
McMahon, JJ, Miller, EE, and Silver, DL. "The exon junction complex in neural development and neurodevelopmental disease." International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience 55 (December 2016): 117-123.
PMID
27071691
Source
epmc
Published In
International Journal of Developmental Neuroscience
Volume
55
Publish Date
2016
Start Page
117
End Page
123
DOI
10.1016/j.ijdevneu.2016.03.006

Dynamic mRNA Transport and Local Translation in Radial Glial Progenitors of the Developing Brain.

In the developing brain, neurons are produced from neural stem cells termed radial glia [1, 2]. Radial glial progenitors span the neuroepithelium, extending long basal processes to form endfeet hundreds of micrometers away from the soma. Basal structures influence neuronal migration, tissue integrity, and proliferation [3-7]. Yet, despite the significance of these distal structures, their cell biology remains poorly characterized, impeding our understanding of how basal processes and endfeet influence neurogenesis. Here we use live imaging of embryonic brain tissue to visualize, for the first time, rapid mRNA transport in radial glia, revealing that the basal process is a highway for directed molecular transport. RNA- and mRNA-binding proteins, including the syndromic autism protein FMRP, move in basal processes at velocities consistent with microtubule-based transport, accumulating in endfeet. We develop an ex vivo tissue preparation to mechanically isolate radial glia endfeet from the soma, and we use photoconvertible proteins to demonstrate that mRNA is locally translated. Using RNA immunoprecipitation and microarray analyses of endfeet, we discover FMRP-bound transcripts, which encode signaling and cytoskeletal regulators, including many implicated in autism and neurogenesis. We show FMRP controls transport and localization of one target, Kif26a. These discoveries reveal a rich, regulated local transcriptome in radial glia, far from the soma, and establish a tractable mammalian model for studying mRNA transport and local translation in vivo. We conclude that cytoskeletal and signaling events at endfeet may be controlled through translation of specific mRNAs transported from the soma, exposing new mechanistic layers within stem cells of the developing brain.

Authors
Pilaz, L-J; Lennox, AL; Rouanet, JP; Silver, DL
MLA Citation
Pilaz, L-J, Lennox, AL, Rouanet, JP, and Silver, DL. "Dynamic mRNA Transport and Local Translation in Radial Glial Progenitors of the Developing Brain." Current biology : CB 26.24 (December 2016): 3383-3392.
PMID
27916527
Source
epmc
Published In
Current Biology
Volume
26
Issue
24
Publish Date
2016
Start Page
3383
End Page
3392
DOI
10.1016/j.cub.2016.10.040

Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly.

The exon junction complex (EJC) is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling. Using a new conditional allele, we first show that Eif4a3 haploinsufficiency phenocopies aberrant neurogenesis and microcephaly of Magoh and Rbm8a mutant mice. Transcriptomic and proteomic analyses of embryonic brains at the onset of neurogenesis identifies common pathways altered in each of the 3 EJC mutants, including ribosome, proteasome, and p53 signaling components. We further demonstrate all 3 mutants exhibit defective splicing of RNA regulatory proteins, implying an EJC dependent RNA regulatory network that fine-tunes gene expression. Finally, we show that genetic ablation of one downstream pathway, p53, significantly rescues microcephaly of all 3 EJC mutants. This implicates p53 activation as a major node of neurodevelopmental pathogenesis following EJC impairment. Altogether our study reveals new mechanisms to help explain how EJC mutations influence neurogenesis and underlie neurodevelopmental disease.

Authors
Mao, H; McMahon, JJ; Tsai, Y-H; Wang, Z; Silver, DL
MLA Citation
Mao, H, McMahon, JJ, Tsai, Y-H, Wang, Z, and Silver, DL. "Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly." PLoS genetics 12.9 (September 12, 2016): e1006282-.
Website
http://hdl.handle.net/10161/12975
PMID
27618312
Source
epmc
Published In
PLoS genetics
Volume
12
Issue
9
Publish Date
2016
Start Page
e1006282
DOI
10.1371/journal.pgen.1006282

Genomic divergence and brain evolution: How regulatory DNA influences development of the cerebral cortex.

The cerebral cortex controls our most distinguishing higher cognitive functions. Human-specific gene expression differences are abundant in the cerebral cortex, yet we have only begun to understand how these variations impact brain function. This review discusses the current evidence linking non-coding regulatory DNA changes, including enhancers, with neocortical evolution. Functional interrogation using animal models reveals converging roles for our genome in key aspects of cortical development including progenitor cell cycle and neuronal signaling. New technologies, including iPS cells and organoids, offer potential alternatives to modeling evolutionary modifications in a relevant species context. Several diseases rooted in the cerebral cortex uniquely manifest in humans compared to other primates, thus highlighting the importance of understanding human brain differences. Future studies of regulatory loci, including those implicated in disease, will collectively help elucidate key cellular and genetic mechanisms underlying our distinguishing cognitive traits.

Authors
Silver, DL
MLA Citation
Silver, DL. "Genomic divergence and brain evolution: How regulatory DNA influences development of the cerebral cortex." BioEssays : news and reviews in molecular, cellular and developmental biology 38.2 (February 2016): 162-171. (Review)
PMID
26642006
Source
epmc
Published In
Bioessays
Volume
38
Issue
2
Publish Date
2016
Start Page
162
End Page
171
DOI
10.1002/bies.201500108

Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain

Authors
Pilaz, L-J; McMahon, JJ; Miller, EE; Lennox, AL; Suzuki, A; Salmon, E; Silver, DL
MLA Citation
Pilaz, L-J, McMahon, JJ, Miller, EE, Lennox, AL, Suzuki, A, Salmon, E, and Silver, DL. "Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain." NEURON 89.1 (January 6, 2016): 83-99.
Source
wos-lite
Published In
Neuron
Volume
89
Issue
1
Publish Date
2016
Start Page
83
End Page
99
DOI
10.1016/j.neuron.2015.12.007

Astrocytes Assemble Thalamocortical Synapses by Bridging NRX1α and NL1 via Hevin.

Proper establishment of synapses is critical for constructing functional circuits. Interactions between presynaptic neurexins and postsynaptic neuroligins coordinate the formation of synaptic adhesions. An isoform code determines the direct interactions of neurexins and neuroligins across the synapse. However, whether extracellular linker proteins can expand such a code is unknown. Using a combination of in vitro and in vivo approaches, we found that hevin, an astrocyte-secreted synaptogenic protein, assembles glutamatergic synapses by bridging neurexin-1alpha and neuroligin-1B, two isoforms that do not interact with each other. Bridging of neurexin-1alpha and neuroligin-1B via hevin is critical for the formation and plasticity of thalamocortical connections in the developing visual cortex. These results show that astrocytes promote the formation of synapses by modulating neurexin/neuroligin adhesions through hevin secretion. Our findings also provide an important mechanistic insight into how mutations in these genes may lead to circuit dysfunction in diseases such as autism.

Authors
Singh, SK; Stogsdill, JA; Pulimood, NS; Dingsdale, H; Kim, YH; Pilaz, L-J; Kim, IH; Manhaes, AC; Rodrigues, WS; Pamukcu, A; Enustun, E; Ertuz, Z; Scheiffele, P; Soderling, SH; Silver, DL; Ji, R-R; Medina, AE; Eroglu, C
MLA Citation
Singh, SK, Stogsdill, JA, Pulimood, NS, Dingsdale, H, Kim, YH, Pilaz, L-J, Kim, IH, Manhaes, AC, Rodrigues, WS, Pamukcu, A, Enustun, E, Ertuz, Z, Scheiffele, P, Soderling, SH, Silver, DL, Ji, R-R, Medina, AE, and Eroglu, C. "Astrocytes Assemble Thalamocortical Synapses by Bridging NRX1α and NL1 via Hevin." Cell 164.1-2 (January 2016): 183-196.
PMID
26771491
Source
epmc
Published In
Cell
Volume
164
Issue
1-2
Publish Date
2016
Start Page
183
End Page
196
DOI
10.1016/j.cell.2015.11.034

Post-transcriptional regulation in corticogenesis: how RNA-binding proteins help build the brain.

The cerebral cortex, the brain structure responsible for our higher cognitive functions, is built during embryonic development in a process called corticogenesis. During corticogenesis, neural stem cells generate distinct populations of progenitors and excitatory neurons. These new neurons migrate radially in the cortex, eventually forming neuronal layers and establishing synaptic connections with other neurons both within and outside the cortex. Perturbations to corticogenesis can result in severe neurodevelopmental disorders, thus emphasizing the need to better understand molecular regulation of brain development. Recent studies in both model organisms and humans have collectively highlighted roles for post-transcriptional regulation in virtually all steps of corticogenesis. Genomic approaches have revealed global RNA changes associated with spatial and temporal regulation of cortical development. Additionally, genetic studies have uncovered RNA-binding proteins (RBPs) critical for cell proliferation, differentiation, and migration within the developing neocortex. Many of these same RBPs play causal roles in neurodevelopmental pathologies. In the developing neocortex, RBPs influence diverse steps of mRNA metabolism, including splicing, stability, translation, and localization. With the advent of new technologies, researchers have begun to uncover key transcripts regulated by these RBPs. Given the complexity of the developing mammalian cortex, a major challenge for the future will be to understand how dynamic RNA regulation occurs within heterogeneous cell populations, across space and time. In sum, post-transcriptional regulation has emerged as a critical mechanism for driving corticogenesis and exciting direction of future research.

Authors
Pilaz, L-J; Silver, DL
MLA Citation
Pilaz, L-J, and Silver, DL. "Post-transcriptional regulation in corticogenesis: how RNA-binding proteins help build the brain." Wiley interdisciplinary reviews. RNA 6.5 (September 2015): 501-515. (Review)
PMID
26088328
Source
epmc
Published In
Wiley interdisciplinary reviews. RNA
Volume
6
Issue
5
Publish Date
2015
Start Page
501
End Page
515
DOI
10.1002/wrna.1289

Rbm8a haploinsufficiency disrupts embryonic cortical development resulting in microcephaly.

The cerebral cortex is built during embryonic neurogenesis, a period when excitatory neurons are generated from progenitors. Defects in neurogenesis can cause acute neurodevelopmental disorders, such as microcephaly (reduced brain size). Altered dosage of the 1q21.1 locus has been implicated in the etiology of neurodevelopmental phenotypes; however, the role of 1q21.1 genes in neurogenesis has remained elusive. Here, we show that haploinsufficiency for Rbm8a, an exon junction complex (EJC) component within 1q21.1, causes severe microcephaly and defective neurogenesis in the mouse. At the onset of neurogenesis, Rbm8a regulates radial glia proliferation and prevents premature neuronal differentiation. Reduced Rbm8a levels result in subsequent apoptosis of neurons, and to a lesser extent, radial glia. Hence, compared to control, Rbm8a-haploinsufficient brains have fewer progenitors and neurons, resulting in defective cortical lamination. To determine whether reciprocal dosage change of Rbm8a alters embryonic neurogenesis, we overexpressed human RBM8A in two animal models. Using in utero electroporation of mouse neocortices as well as zebrafish models, we find RBM8A overexpression does not significantly perturb progenitor number or head size. Our findings demonstrate that Rbm8a is an essential neurogenesis regulator, and add to a growing literature highlighting roles for EJC components in cortical development and neurodevelopmental pathology. Our results indicate that disruption of RBM8A may contribute to neurodevelopmental phenotypes associated with proximal 1q21.1 microdeletions.

Authors
Mao, H; Pilaz, L-J; McMahon, JJ; Golzio, C; Wu, D; Shi, L; Katsanis, N; Silver, DL
MLA Citation
Mao, H, Pilaz, L-J, McMahon, JJ, Golzio, C, Wu, D, Shi, L, Katsanis, N, and Silver, DL. "Rbm8a haploinsufficiency disrupts embryonic cortical development resulting in microcephaly." The Journal of neuroscience : the official journal of the Society for Neuroscience 35.18 (May 2015): 7003-7018.
PMID
25948253
Source
epmc
Published In
The Journal of neuroscience : the official journal of the Society for Neuroscience
Volume
35
Issue
18
Publish Date
2015
Start Page
7003
End Page
7018
DOI
10.1523/jneurosci.0018-15.2015

Human-chimpanzee differences in a FZD8 enhancer alter cell-cycle dynamics in the developing neocortex.

The human neocortex differs from that of other great apes in several notable regards, including altered cell cycle, prolonged corticogenesis, and increased size [1-5]. Although these evolutionary changes most likely contributed to the origin of distinctively human cognitive faculties, their genetic basis remains almost entirely unknown. Highly conserved non-coding regions showing rapid sequence changes along the human lineage are candidate loci for the development and evolution of uniquely human traits. Several studies have identified human-accelerated enhancers [6-14], but none have linked an expression difference to a specific organismal trait. Here we report the discovery of a human-accelerated regulatory enhancer (HARE5) of FZD8, a receptor of the Wnt pathway implicated in brain development and size [15, 16]. Using transgenic mice, we demonstrate dramatic differences in human and chimpanzee HARE5 activity, with human HARE5 driving early and robust expression at the onset of corticogenesis. Similar to HARE5 activity, FZD8 is expressed in neural progenitors of the developing neocortex [17-19]. Chromosome conformation capture assays reveal that HARE5 physically and specifically contacts the core Fzd8 promoter in the mouse embryonic neocortex. To assess the phenotypic consequences of HARE5 activity, we generated transgenic mice in which Fzd8 expression is under control of orthologous enhancers (Pt-HARE5::Fzd8 and Hs-HARE5::Fzd8). In comparison to Pt-HARE5::Fzd8, Hs-HARE5::Fzd8 mice showed marked acceleration of neural progenitor cell cycle and increased brain size. Changes in HARE5 function unique to humans thus alter the cell-cycle dynamics of a critical population of stem cells during corticogenesis and may underlie some distinctive anatomical features of the human brain.

Authors
Boyd, JL; Skove, SL; Rouanet, JP; Pilaz, L-J; Bepler, T; Gordân, R; Wray, GA; Silver, DL
MLA Citation
Boyd, JL, Skove, SL, Rouanet, JP, Pilaz, L-J, Bepler, T, Gordân, R, Wray, GA, and Silver, DL. "Human-chimpanzee differences in a FZD8 enhancer alter cell-cycle dynamics in the developing neocortex." Current biology : CB 25.6 (March 2015): 772-779.
Website
http://hdl.handle.net/10161/9492
PMID
25702574
Source
epmc
Published In
Current Biology
Volume
25
Issue
6
Publish Date
2015
Start Page
772
End Page
779
DOI
10.1016/j.cub.2015.01.041

Astrocytes refine cortical connectivity at dendritic spines.

During cortical synaptic development, thalamic axons must establish synaptic connections despite the presence of the more abundant intracortical projections. How thalamocortical synapses are formed and maintained in this competitive environment is unknown. Here, we show that astrocyte-secreted protein hevin is required for normal thalamocortical synaptic connectivity in the mouse cortex. Absence of hevin results in a profound, long-lasting reduction in thalamocortical synapses accompanied by a transient increase in intracortical excitatory connections. Three-dimensional reconstructions of cortical neurons from serial section electron microscopy (ssEM) revealed that, during early postnatal development, dendritic spines often receive multiple excitatory inputs. Immuno-EM and confocal analyses revealed that majority of the spines with multiple excitatory contacts (SMECs) receive simultaneous thalamic and cortical inputs. Proportion of SMECs diminishes as the brain develops, but SMECs remain abundant in Hevin-null mice. These findings reveal that, through secretion of hevin, astrocytes control an important developmental synaptic refinement process at dendritic spines.

Authors
Risher, WC; Patel, S; Kim, IH; Uezu, A; Bhagat, S; Wilton, DK; Pilaz, L-J; Singh Alvarado, J; Calhan, OY; Silver, DL; Stevens, B; Calakos, N; Soderling, SH; Eroglu, C
MLA Citation
Risher, WC, Patel, S, Kim, IH, Uezu, A, Bhagat, S, Wilton, DK, Pilaz, L-J, Singh Alvarado, J, Calhan, OY, Silver, DL, Stevens, B, Calakos, N, Soderling, SH, and Eroglu, C. "Astrocytes refine cortical connectivity at dendritic spines." eLife 3 (December 17, 2014).
Website
http://hdl.handle.net/10161/9362
PMID
25517933
Source
epmc
Published In
eLife
Volume
3
Publish Date
2014
DOI
10.7554/elife.04047

Elucidating the role of the RNA binding exon junction complex in mitosis

Authors
Miller, EE; Suzuki, A; Pilaz, L; Salmon, ED; Silver, DL
MLA Citation
Miller, EE, Suzuki, A, Pilaz, L, Salmon, ED, and Silver, DL. "Elucidating the role of the RNA binding exon junction complex in mitosis." December 2014.
Source
wos-lite
Published In
Molecular Biology of the Cell
Volume
25
Publish Date
2014

Generation of a Magoh conditional allele in mice.

Magoh encodes a core component of the exon junction complex (EJC), which binds mRNA and regulates mRNA metabolism. Magoh is highly expressed in proliferative tissues during development. EJC components have been implicated in several developmental disorders including TAR syndrome, Richieri-Costa-Pereira syndrome, and intellectual disability. Existing germline null Magoh mice are embryonic lethal as homozygotes and perinatal lethal as heterozygotes, precluding detailed analysis of embryonic and postnatal functions. Here, we report the generation of a new genetic tool to dissect temporal and tissue-specific roles for Magoh in development and adult homeostasis. This Magoh conditional allele has two loxP sites flanking the second exon. Ubiquitous Cre-mediated deletion of the floxed allele in a heterozygous mouse (Magoh(del/+) ) causes 50% reduction of both Magoh mRNA and protein. Magoh(del/+) mice exhibit both microcephaly and hypopigmentation, thus phenocopying germline haploinsufficient Magoh mice. Using Emx1-Cre, we further show that conditional Magoh deletion in neural progenitors during embryonic development also causes microcephaly. We anticipate this novel conditional allele will be a valuable tool for assessing tissue-specific roles for Magoh in mammalian development and postnatal processes.

Authors
McMahon, JJ; Shi, L; Silver, DL
MLA Citation
McMahon, JJ, Shi, L, and Silver, DL. "Generation of a Magoh conditional allele in mice." Genesis (New York, N.Y. : 2000) 52.8 (August 2014): 752-758.
PMID
24771530
Source
epmc
Published In
Genesis: the Journal of Genetics and Development
Volume
52
Issue
8
Publish Date
2014
Start Page
752
End Page
758
DOI
10.1002/dvg.22788

Live imaging of mitosis in the developing mouse embryonic cortex.

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the developing cerebral cortex, abnormal mitosis of neural progenitors can cause defects in brain size and function. Hence, there is a critical need for tools to understand the mechanisms of neural progenitor mitosis. Cortical development in rodents is an outstanding model for studying this process. Neural progenitor mitosis is commonly examined in fixed brain sections. This protocol will describe in detail an approach for live imaging of mitosis in ex vivo embryonic brain slices. We will describe the critical steps for this procedure, which include: brain extraction, brain embedding, vibratome sectioning of brain slices, staining and culturing of slices, and time-lapse imaging. We will then demonstrate and describe in detail how to perform post-acquisition analysis of mitosis. We include representative results from this assay using the vital dye Syto11, transgenic mice (histone H2B-EGFP and centrin-EGFP), and in utero electroporation (mCherry-α-tubulin). We will discuss how this procedure can be best optimized and how it can be modified for study of genetic regulation of mitosis. Live imaging of mitosis in brain slices is a flexible approach to assess the impact of age, anatomy, and genetic perturbation in a controlled environment, and to generate a large amount of data with high temporal and spatial resolution. Hence this protocol will complement existing tools for analysis of neural progenitor mitosis.

Authors
Pilaz, L-J; Silver, DL
MLA Citation
Pilaz, L-J, and Silver, DL. "Live imaging of mitosis in the developing mouse embryonic cortex." Journal of visualized experiments : JoVE 88 (June 4, 2014).
PMID
24961595
Source
epmc
Published In
Journal of Visualized Experiments
Issue
88
Publish Date
2014
DOI
10.3791/51298

Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy.

We analyzed four families that presented with a similar condition characterized by congenital microcephaly, intellectual disability, progressive cerebral atrophy, and intractable seizures. We show that recessive mutations in the ASNS gene are responsible for this syndrome. Two of the identified missense mutations dramatically reduce ASNS protein abundance, suggesting that the mutations cause loss of function. Hypomorphic Asns mutant mice have structural brain abnormalities, including enlarged ventricles and reduced cortical thickness, and show deficits in learning and memory mimicking aspects of the patient phenotype. ASNS encodes asparagine synthetase, which catalyzes the synthesis of asparagine from glutamine and aspartate. The neurological impairment resulting from ASNS deficiency may be explained by asparagine depletion in the brain or by accumulation of aspartate/glutamate leading to enhanced excitability and neuronal damage. Our study thus indicates that asparagine synthesis is essential for the development and function of the brain but not for that of other organs.

Authors
Ruzzo, EK; Capo-Chichi, J-M; Ben-Zeev, B; Chitayat, D; Mao, H; Pappas, AL; Hitomi, Y; Lu, Y-F; Yao, X; Hamdan, FF; Pelak, K; Reznik-Wolf, H; Bar-Joseph, I; Oz-Levi, D; Lev, D; Lerman-Sagie, T; Leshinsky-Silver, E; Anikster, Y; Ben-Asher, E; Olender, T; Colleaux, L; Décarie, J-C; Blaser, S; Banwell, B; Joshi, RB; He, X-P; Patry, L; Silver, RJ; Dobrzeniecka, S; Islam, MS; Hasnat, A; Samuels, ME; Aryal, DK; Rodriguiz, RM; Jiang, Y-H; Wetsel, WC; McNamara, JO; Rouleau, GA; Silver, DL; Lancet, D et al.
MLA Citation
Ruzzo, EK, Capo-Chichi, J-M, Ben-Zeev, B, Chitayat, D, Mao, H, Pappas, AL, Hitomi, Y, Lu, Y-F, Yao, X, Hamdan, FF, Pelak, K, Reznik-Wolf, H, Bar-Joseph, I, Oz-Levi, D, Lev, D, Lerman-Sagie, T, Leshinsky-Silver, E, Anikster, Y, Ben-Asher, E, Olender, T, Colleaux, L, Décarie, J-C, Blaser, S, Banwell, B, Joshi, RB, He, X-P, Patry, L, Silver, RJ, Dobrzeniecka, S, Islam, MS, Hasnat, A, Samuels, ME, Aryal, DK, Rodriguiz, RM, Jiang, Y-H, Wetsel, WC, McNamara, JO, Rouleau, GA, Silver, DL, and Lancet, D et al. "Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy." Neuron 80.2 (October 16, 2013): 429-441.
PMID
24139043
Source
pubmed
Published In
Neuron
Volume
80
Issue
2
Publish Date
2013
Start Page
429
End Page
441
DOI
10.1016/j.neuron.2013.08.013

The EJC component Magoh regulates proliferation and expansion of neural crest-derived melanocytes.

Melanoblasts are a population of neural crest-derived cells that generate the pigment-producing cells of our body. Defective melanoblast development and function underlies many disorders including Waardenburg syndrome and melanoma. Understanding the genetic regulation of melanoblast development will help elucidate the etiology of these and other neurocristopathies. Here we demonstrate that Magoh, a component of the exon junction complex, is required for normal melanoblast development. Magoh haploinsufficient mice are hypopigmented and exhibit robust genetic interactions with the transcription factor, Sox10. These phenotypes are caused by a marked reduction in melanoblast number beginning at mid-embryogenesis. Strikingly, while Magoh haploinsufficiency severely reduces epidermal melanoblasts, it does not significantly affect the number of dermal melanoblasts. These data indicate Magoh impacts melanoblast development by disproportionately affecting expansion of epidermal melanoblast populations. We probed the cellular basis for melanoblast reduction and discovered that Magoh mutant melanoblasts do not undergo increased apoptosis, but instead are arrested in mitosis. Mitotic arrest is evident in both Magoh haploinsufficient embryos and in Magoh siRNA treated melanoma cell lines. Together our findings indicate that Magoh-regulated proliferation of melanoblasts in the dermis may be critical for production of epidermally-bound melanoblasts. Our results point to a central role for Magoh in melanocyte development.

Authors
Silver, DL; Leeds, KE; Hwang, H-W; Miller, EE; Pavan, WJ
MLA Citation
Silver, DL, Leeds, KE, Hwang, H-W, Miller, EE, and Pavan, WJ. "The EJC component Magoh regulates proliferation and expansion of neural crest-derived melanocytes." Dev Biol 375.2 (March 15, 2013): 172-181.
PMID
23333945
Source
pubmed
Published In
Developmental Biology
Volume
375
Issue
2
Publish Date
2013
Start Page
172
End Page
181
DOI
10.1016/j.ydbio.2013.01.004

Genetic interaction screens identify a role for hedgehog signaling in drosophila border cell migration

Background: Cell motility is essential for embryonic development and physiological processes such as the immune response, but also contributes to pathological conditions such as tumor progression and inflammation. However, our understanding of the mechanisms underlying migratory processes is incomplete. Drosophila border cells provide a powerful genetic model to identify the roles of genes that contribute to cell migration. Results: Members of the Hedgehog signaling pathway were uncovered in two independent screens for interactions with the small GTPase Rac and the polarity protein Par-1 in border cell migration. Consistent with a role in migration, multiple Hh signaling components were enriched in the migratory border cells. Interference with Hh signaling by several different methods resulted in incomplete cell migration. Moreover, the polarized distribution of E-Cadherin and a marker of tyrosine kinase activity were altered when Hh signaling was disrupted. Conservation of Hh-Rac and Hh-Par-1 signaling was illustrated in the wing, in which Hh-dependent phenotypes were enhanced by loss of Rac or par-1. Conclusions: We identified a pathway by which Hh signaling connects to Rac and Par-1 in cell migration. These results further highlight the importance of modifier screens in the identification of new genes that function in developmental pathways. © 2013 Wiley Periodicals, Inc.

Authors
Geisbrecht, ER; Sawant, K; Su, Y; Liu, ZC; Silver, DL; Burtscher, A; Wang, X; Zhu, AJ; Mcdonald, JA
MLA Citation
Geisbrecht, ER, Sawant, K, Su, Y, Liu, ZC, Silver, DL, Burtscher, A, Wang, X, Zhu, AJ, and Mcdonald, JA. "Genetic interaction screens identify a role for hedgehog signaling in drosophila border cell migration." Developmental Dynamics 242.5 (2013): 414-431.
Source
scival
Published In
Developmental Dynamics
Volume
242
Issue
5
Publish Date
2013
Start Page
414
End Page
431
DOI
10.1002/dvdy.23926

The exon junction complex component Magoh controls brain size by regulating neural stem cell division

Brain structure and size require precise division of neural stem cells (NSCs), which self-renew and generate intermediate neural progenitors (INPs) and neurons. The factors that regulate NSCs remain poorly understood, and mechanistic explanations of how aberrant NSC division causes the reduced brain size seen in microcephaly are lacking. Here we show that Magoh, a component of the exon junction complex (EJC) that binds RNA, controls mouse cerebral cortical size by regulating NSC division. Magoh haploinsufficiency causes microcephaly because of INP depletion and neuronal apoptosis. Defective mitosis underlies these phenotypes, as depletion of EJC components disrupts mitotic spindle orientation and integrity, chromosome number and genomic stability. In utero rescue experiments showed that a key function of Magoh is to control levels of the microcephaly-associated protein Lis1 during neurogenesis. Our results uncover requirements for the EJC in brain development, NSC maintenance and mitosis, thereby implicating this complex in the pathogenesis of microcephaly. © 2010 Nature America, Inc. All rights reserved.

Authors
Silver, DL; Watkins-Chow, DE; Schreck, KC; Pierfelice, TJ; Larson, DM; Burnetti, AJ; Liaw, H-J; Myung, K; Walsh, CA; Gaiano, N; Pavan, WJ
MLA Citation
Silver, DL, Watkins-Chow, DE, Schreck, KC, Pierfelice, TJ, Larson, DM, Burnetti, AJ, Liaw, H-J, Myung, K, Walsh, CA, Gaiano, N, and Pavan, WJ. "The exon junction complex component Magoh controls brain size by regulating neural stem cell division." Nature Neuroscience 13.5 (2010): 551-558.
PMID
20364144
Source
scival
Published In
Nature Neuroscience
Volume
13
Issue
5
Publish Date
2010
Start Page
551
End Page
558
DOI
10.1038/nn.2527

ADAMTS Metalloproteases Generate Active Versican Fragments that Regulate Interdigital Web Regression

We show that combinatorial mouse alleles for the secreted metalloproteases Adamts5, Adamts20 (bt), and Adamts9 result in fully penetrant soft-tissue syndactyly. Interdigital webs in Adamts5-/-;bt/bt mice had reduced apoptosis and decreased cleavage of the proteoglycan versican; however, the BMP-FGF axis, which regulates interdigital apoptosis was unaffected. BMP4 induced apoptosis, but without concomitant versican proteolysis. Haploinsufficiency of either Vcan or Fbln1, a cofactor for versican processing by ADAMTS5, led to highly penetrant syndactyly in bt mice, suggesting that cleaved versican was essential for web regression. The local application of an aminoterminal versican fragment corresponding to ADAMTS-processed versican, induced cell death in Adamts5-/-;bt/bt webs. Thus, ADAMTS proteases cooperatively maintain versican proteolysis above a required threshold to create a permissive environment for apoptosis. The data highlight the developmental significance of proteolytic action on the ECM, not only as a clearance mechanism, but also as a means to generate bioactive versican fragments. © 2009 Elsevier Inc. All rights reserved.

Authors
McCulloch, DR; Nelson, CM; Dixon, LJ; Silver, DL; Wylie, JD; Lindner, V; Sasaki, T; Cooley, MA; Argraves, WS; Apte, SS
MLA Citation
McCulloch, DR, Nelson, CM, Dixon, LJ, Silver, DL, Wylie, JD, Lindner, V, Sasaki, T, Cooley, MA, Argraves, WS, and Apte, SS. "ADAMTS Metalloproteases Generate Active Versican Fragments that Regulate Interdigital Web Regression." Developmental Cell 17.5 (2009): 687-698.
PMID
19922873
Source
scival
Published In
Developmental Cell
Volume
17
Issue
5
Publish Date
2009
Start Page
687
End Page
698
DOI
10.1016/j.devcel.2009.09.008

A sensitized mutagenesis screen identifies Gli3 as a modifier of Sox10 neurocristopathy

Haploinsufficiency for the transcription factor SOX10 is associated with the pigmentary deficiencies of Waardenburg syndrome (WS) and is modeled in Sox10 haploinsufficient mice (Sox10LacZ/+). As genetic background affects WS severity in both humans and mice, we established an N-ethyl-N-nitrosourea (ENU) mutagenesis screen to identify modifiers that increase the phenotypic severity of Sox10LacZ/+ mice. Analysis of 230 pedigrees identified three modifiers, named modifier of Sox10 neurocristopathies (Mos1, Mos2 and Mos3). Linkage analysis confirmed their locations on mouse chromosomes 13, 4 and 3, respectively, within regions distinct from previously identified WS loci. Positional candidate analysis of Mos1 identified a truncation mutation in a hedgehog(HH)-signaling mediator, GLI-Kruppel family member 3 (Gli3). Complementation tests using a second allele of Gli3 (Gli3Xt-J) confirmed that a null mutation of Gli3 causes the increased hypopigmentation in Sox10LacZ/+; Gli3Mos1/+ double heterozygotes. Early melanoblast markers (Mitf, Sox10, Dct, and Si) are reduced in Gli3Mos1/Mos1 embryos, indicating that loss of GLI3 signaling disrupts melanoblast specification. In contrast, mice expressing only the GLI3 repressor have normal melanoblast specification, indicating that the full-length GLI3 activator is not required for specification of neural crest to the melanocyte lineage. This study demonstrates the feasibility of sensitized screens to identify disease modifier loci and implicates GLI3 and other HH signaling components as modifiers of human neurocristopathies. © The Author 2008. Published by Oxford University Press. All rights reserved.

Authors
Matera, I; Watkins-Chow, DE; Loftus, SK; Hou, L; Incao, A; Silver, DL; Rivas, C; Elliott, EC; Baxter, LL; Pavan, WJ
MLA Citation
Matera, I, Watkins-Chow, DE, Loftus, SK, Hou, L, Incao, A, Silver, DL, Rivas, C, Elliott, EC, Baxter, LL, and Pavan, WJ. "A sensitized mutagenesis screen identifies Gli3 as a modifier of Sox10 neurocristopathy." Human Molecular Genetics 17.14 (2008): 2118-2131.
PMID
18397875
Source
scival
Published In
Human Molecular Genetics
Volume
17
Issue
14
Publish Date
2008
Start Page
2118
End Page
2131
DOI
10.1093/hmg/ddn110

The secreted metalloprotease ADAMTS20 is required for melanoblast survival

ADAMTS20 (A disintegrin-like and metalloprotease domain with thrombospondin type-1 motifs) is a member of a family of secreted metalloproteases that can process a variety of extracellular matrix (ECM) components and secreted molecules. Adamts20 mutations in belted (bt) mice cause white spotting of the dorsal and ventral torso, indicative of defective neural crest (NC)-derived melanoblast development. The expression pattern of Adamts20 in dermal mesenchymal cells adjacent to migrating melanoblasts led us to initially propose that Adamts20 regulated melanoblast migration. However, using a Dct-LacZ transgene to track melanoblast development, we determined that melanoblasts were distributed normally in whole mount E12.5 bt/bt embryos, but were specifically reduced in the trunk of E13.5 bt/bt embryos due to a seven-fold higher rate of apoptosis. The melanoblast defect was exacerbated in newborn skin and embryos from bt/bt animals that were also haploinsufficient for Adamts9, a close homolog of Adamts20, indicating that these metalloproteases functionally overlap in melanoblast development. We identified two potential mechanisms by which Adamts20 may regulate melanoblast survival. First, skin explant cultures demonstrated that Adamts20 was required for melanoblasts to respond to soluble Kit ligand (sKitl). In support of this requirement, bt/bt;Kittm1Alf/+ and bt/bt;KitlSl/+ mice exhibited synergistically increased spotting. Second, ADAMTS20 cleaved the aggregating proteoglycan versican in vitro and was necessary for versican processing in vivo, raising the possibility that versican can participate in melanoblast development. These findings reveal previously unrecognized roles for Adamts proteases in cell survival and in mediating Kit signaling during melanoblast colonization of the skin. Our results have implications not only for understanding mechanisms of NC-derived melanoblast development but also provide insights on novel biological functions of secreted metalloproteases.

Authors
Silver, DL; Hou, L; Somerville, R; Young, ME; Apte, SS; Pavan, WJ
MLA Citation
Silver, DL, Hou, L, Somerville, R, Young, ME, Apte, SS, and Pavan, WJ. "The secreted metalloprotease ADAMTS20 is required for melanoblast survival." PLoS Genetics 4.2 (2008).
PMID
18454205
Source
scival
Published In
PLoS genetics
Volume
4
Issue
2
Publish Date
2008
DOI
10.1371/journal.pgen.1000003

The origin and development of neural crest-derived melanocytes

Melanocytes are specified from pluripotent neural crest cells that delaminate from the developing neural tube and overlying ectoderm early in development. As a subset of these neural crest cells migrate along the dorsal-lateral path, they begin to differentiate into melanocyte precursors (called melanoblasts). While the melanoblasts continue to differentiate, the population expands through proliferation and prosurvival processes. Melanoblasts eventually migrate through the dermis, into the epidermis, and, in mice and humans, into hair follicles, in which they produce melanin. Several classes of proteins, including transcription factors, extracellular ligands, transmembrane receptors, and intracellular signaling molecules regulate these processes. The genes that are currently implicated in melanocyte development and their relationship with each other will be discussed in this chapter. © 2006 Humana Press Inc.

Authors
Silver, DL; Pavan, WJ
MLA Citation
Silver, DL, and Pavan, WJ. "The origin and development of neural crest-derived melanocytes." (December 1, 2006): 3-26. (Chapter)
Source
scopus
Publish Date
2006
Start Page
3
End Page
26
DOI
10.1007/978-1-59259-994-3_1

The genetic regulation of pigment cell development

Pigment cells in developing vertebrates are derived from a transient and pluripotent population of cells called neural crest. The neural crest delaminates from the developing neural tube and overlying ectoderm early in development. The pigment cells are the only derivative to migrate along the dorso-lateral pathway. As they migrate, the precursor pigment cell population differentiates and expands through proliferation and pro-survival processes, ultimately contributing to the coloration of organisms. The types of pigment cells that develop, timing of these processes, and final destination can vary between organisms. Studies from mice, chick, Xenopus, zebrafish, and medaka have led to the identification of many genes that regulate pigment cell development. These include several classes of proteins: transcription factors, transmembrane receptors, and extracellular ligands. This chapter discusses an overview of pigment cell development and the genes that regulate this important process. © 2006 Landes Bioscience and Springer Science+Business Media, LLC.

Authors
Silver, DL; Hou, L; Pavan, WJ
MLA Citation
Silver, DL, Hou, L, and Pavan, WJ. "The genetic regulation of pigment cell development." Advances in Experimental Medicine and Biology 589 (January 1, 2006): 155-169. (Review)
Source
scopus
Published In
Advances in experimental medicine and biology
Volume
589
Publish Date
2006
Start Page
155
End Page
169
DOI
10.1007/978-0-387-46954-6_9

Requirement for JAK/STAT signaling throughout border cell migration in Drosophila

The evolutionarily conserved JAK/STAT signaling pathway is essential for the proliferation, survival and differentiation of many cells including cancer cells. Recent studies have implicated this transcriptional pathway in the process of cell migration in humans, mice, Drosophila and Dictyostelium. In the Drosophila ovary, JAK/STAT signaling is necessary and sufficient for the specification and migration of a group of cells called the border cells; however, it is not clear to what extent the requirement for cell fate is distinct from that for cell migration. We found that STAT protein is enriched in the migrating border cells throughout their migration and is an indicator of cells with highest JAK/STAT activity. In addition, statts mutants exhibited border cell migration defects after just 30 minutes at the non-permissive temperature, prior to any detectable change in the expression of cell fate markers. At later times, cell fate changes became evident, indicating that border cell fate is labile. JAK/STAT signaling was also required for organization of the border cell cluster. Finally, we show that both the accumulation of STAT protein and nuclear accumulation are positively regulated by JAK/STAT activity. The activity of the pathway is negatively regulated by overexpression of a SOCS protein and by blocking endocytosis. Together, our findings suggest that the requirement for STAT in border cells extends beyond the initial specification and delamination of cells from the epithelium.

Authors
Silver, DL; Geisbrecht, ER; Montell, DJ
MLA Citation
Silver, DL, Geisbrecht, ER, and Montell, DJ. "Requirement for JAK/STAT signaling throughout border cell migration in Drosophila." Development 132.15 (2005): 3483-3492.
PMID
16000386
Source
scival
Published In
Development
Volume
132
Issue
15
Publish Date
2005
Start Page
3483
End Page
3492
DOI
10.1242/dev.01910

Activated signal transducer and activator of transcription (STAT) 3: Localization in focal adhesions and function in ovarian cancer cell motility

Constitutive activation of the Janus-activated kinase/signal transducer and activator of transcription (STAT) pathway promotes the proliferation and survival of cancer cells in culture and is associated with various cancers, including those of the ovary. We found that constitutively activated STAT3 levels correlated with aggressive clinical behavior of ovarian carcinoma specimens. Furthermore, inhibition of STAT3 reduced the motility of ovarian cancer cells in vitro. Surprisingly, we found that activated STAT3 localized not only to nuclei but also to focal adhesions in these cells. Activated STAT3 coimmunoprecipitated with phosphorylated paxillin and focal adhesion kinase and required paxillin and Src for its localization to focal adhesions. These results suggest that Janus-activated kinase/STAT signaling may contribute to ovarian cancer cell invasiveness.

Authors
Silver, DL; Naora, H; Liu, J; Cheng, W; Montell, DJ
MLA Citation
Silver, DL, Naora, H, Liu, J, Cheng, W, and Montell, DJ. "Activated signal transducer and activator of transcription (STAT) 3: Localization in focal adhesions and function in ovarian cancer cell motility." Cancer Research 64.10 (2004): 3550-3558.
PMID
15150111
Source
scival
Published In
Cancer Research
Volume
64
Issue
10
Publish Date
2004
Start Page
3550
End Page
3558
DOI
10.1158/0008-5472.CAN-03-3959

A new trick for cyclin-cdk: Activation of STAT

New work in Drosophila demonstrates that cdk4 loss causes phenotypes similar to the loss of JAK/STAT pathway components. Cdk4 overexpression can bypass requirements for JAK but not STAT. These results demonstrate a new function for Cdk4 and a new mode of STAT activation.

Authors
Silver, DL; Montell, DJ
MLA Citation
Silver, DL, and Montell, DJ. "A new trick for cyclin-cdk: Activation of STAT." Developmental Cell 4.2 (2003): 148-149.
PMID
12586057
Source
scival
Published In
Developmental Cell
Volume
4
Issue
2
Publish Date
2003
Start Page
148
End Page
149
DOI
10.1016/S1534-5807(03)00028-5

Paracrine signaling through the JAK/STAT pathway activates invasive behavior of ovarian epithelial cells in drosophila

The JAK/STAT signaling pathway, renowned for its effects on cell proliferation and survival, is constitutively active in various human cancers, including ovarian. We have found that JAK and STAT are required to convert the border cells in the Drosophila ovary from stationary, epithelial cells to migratory, invasive cells. The ligand for this pathway, Unpaired (UPD), is expressed by two central cells within the migratory cell cluster. Mutations in upd or jak cause defects in migration and a reduction in the number of cells recruited to the cluster. Ectopic expression of either UPD or JAK is sufficient to induce extra epithelial cells to migrate. Thus, a localized signal activates the JAK/STAT pathway in neighboring epithelial cells, causing them to become invasive.

Authors
Silver, DL; Montell, DJ
MLA Citation
Silver, DL, and Montell, DJ. "Paracrine signaling through the JAK/STAT pathway activates invasive behavior of ovarian epithelial cells in drosophila." Cell 107.7 (2001): 831-841.
PMID
11779460
Source
scival
Published In
Cell
Volume
107
Issue
7
Publish Date
2001
Start Page
831
End Page
841
DOI
10.1016/S0092-8674(01)00607-9

Tyrosine Phosphorylation of the  3 Cytoplasmic Domain Mediates Integrin-Cytoskeletal Interactions

Authors
Jenkins, AL; Nannizzi-Alaimo, L; Silver, D; Sellers, JR; Ginsberg, MH; Law, DA; Phillips, DR
MLA Citation
Jenkins, AL, Nannizzi-Alaimo, L, Silver, D, Sellers, JR, Ginsberg, MH, Law, DA, and Phillips, DR. "Tyrosine Phosphorylation of the  3 Cytoplasmic Domain Mediates Integrin-Cytoskeletal Interactions." Journal of Biological Chemistry 273.22 (May 29, 1998): 13878-13885.
Source
crossref
Published In
The Journal of biological chemistry
Volume
273
Issue
22
Publish Date
1998
Start Page
13878
End Page
13885
DOI
10.1074/jbc.273.22.13878

Requirement for the Vasa RNA helicase in gurken mRNA localization

Localization of specific mRNAs to distinct sites within the Drosophila oocyte is an early and key step in establishing the anterior-posterior and dorsal-ventral axes. We describe a new function for the RNA helicase encoded by the 'posterior' group gene vasa (vas) in control of localization of the mRNA encoded by the 'dorsal-ventral' patterning gene gurken (grk). Two new ethyl methane sulfonate-induced, female sterile alleles of vas have been isolated. In these mutants grk mRNA fails to become localized properly and GRK protein is barely detectable. Surprisingly fs(1)K10, a recessive female sterile mutation that results in mislocalization of GRK mRNA to the anterior end of the oocyte, is epistatic to these vas alleles. This result demonstrates that GRK protein levels sufficient to dorsalize the egg chamber can accumulate in vas mutants, if fs(1)K10 is also mutant. Taken together these results suggest that regulation of GRK mRNA localization normally occurs, directly or indirectly, through the VAS RNA-dependent RNA helicase and may suggest that accumulation of GRK protein normally depends on GRK mRNA localization.

Authors
Tinker, R; Silver, D; Montell, DJ
MLA Citation
Tinker, R, Silver, D, and Montell, DJ. "Requirement for the Vasa RNA helicase in gurken mRNA localization." Developmental Biology 199.1 (1998): 1-10.
PMID
9676188
Source
scival
Published In
Developmental Biology
Volume
199
Issue
1
Publish Date
1998
Start Page
1
End Page
10
DOI
10.1006/dbio.1998.8941

Sites of interaction between kinase-related protein and smooth muscle myosin

Kinase-related protein, also known as KRP or telokin, is an independently expressed protein product derived from a gene within the gene for myosin light chain kinase (MLCK). KRP binds to unphosphorylated smooth muscle myosin filaments and stabilizes them against ATP-induced depolymerization in vitro. KRP competes with MLCK for binding to myosin, suggesting that both proteins bind to myosin by the KRP domain (Shirinsky, V. P., Vorotnikov, A. V., Birukov, K. G., Nanaev, A. K., Collinge, M., Lukas, T. J., Sellers, J. R., and Watterson, D. M. (1993) J. Biol. Chem. 268, 16578- 16583). In this study, we investigated which regions of myosin and KRP interact in vitro. Using cosedimentation assays, we determined that KRP binds to unphosphorylated myosin with a stoichiometry of 1 mol of KRP/1 mol of myosin and an affinity of 5.5 μm. KRP slows the rate of proteolytic cleavage of the head-tail junction of heavy meromyosin by papain and chymotrypsin, suggesting it is binding to this region of myosin. In addition, competition experiments, using soluble headless fragments of nonmuscle myosin, confirmed that KRP interacts with the regulatory light chain binding region of myosin. The regions important for KRP's binding to myosin were investigated using bacterially expressed KRP truncation mutants. We determined that the acid- rich sequence between Gly138 and Asp151 of KRP is required for high affinity myosin binding, and that the amino terminus and 2b-barrel regions weakly interact with myosin. All KRP truncations, at concentrations comparable to their K(D) values, exhibited some stabilization of myosin filaments against ATP depolymerization in vitro, suggesting that KRP's ability to stabilize myosin filaments is commensurate with its myosin binding affinity. KRP weakened the K(m) but not the V(max) of phosphorylation of myosin by MLCK, demonstrating that bound KRP does not prevent MLCK from activating myosin.

Authors
Silver, DL; Vorotnikov, AV; Watterson, DM; Shirinsky, VP; Sellers, JR
MLA Citation
Silver, DL, Vorotnikov, AV, Watterson, DM, Shirinsky, VP, and Sellers, JR. "Sites of interaction between kinase-related protein and smooth muscle myosin." Journal of Biological Chemistry 272.40 (1997): 25353-25359.
PMID
9312155
Source
scival
Published In
The Journal of biological chemistry
Volume
272
Issue
40
Publish Date
1997
Start Page
25353
End Page
25359
DOI
10.1074/jbc.272.40.25353

Effect of Mts1 on the structure and activity of nonmuscle myosin II

The mts1 gene codes for a 9 kDa protein belonging to the S100 subfamily of Ca2+-binding proteins and is known to play a role in metastasis. Its role in metastasis may be through cellular locomotion, as transfection of mts1 into mouse mammary adenocarcinoma cells increases cellular motility in modified Boyden chemotaxis chambers. The Mts1 protein interacts with nonmuscle myosin II in the presence of Ca2+ with an affinity of approximately 7.9 x 104 M-1 and an approximate stoichiometry of 3 mol of Mts1/mol of myosin heavy chain. No interaction was found with myosin I or myosin V. The binding site of Mts1 on myosin is in the rod region, particularly to the light meromyosin portion of the rod. To understand the mechanism by which Mts1 alters cellular motility, we examined its effect on myosin structure and activity. Cosedimentation analysis and electron microscopy suggest that Mts1 destabilizes myosin filaments. In the presence of Ca2+, Mts1 inhibits the actin-activated MgATPase activity of myosin in vitro. The data demonstrate an effect of Mts1 on both myosin structure and function, and suggest a route through which Mts1 affects motility as well as metastasis.

Authors
Ford, HL; Silver, DL; Kachar, B; Sellers, JR; Zain, SB
MLA Citation
Ford, HL, Silver, DL, Kachar, B, Sellers, JR, and Zain, SB. "Effect of Mts1 on the structure and activity of nonmuscle myosin II." Biochemistry 36.51 (1997): 16321-16327.
PMID
9405067
Source
scival
Published In
Biochemistry
Volume
36
Issue
51
Publish Date
1997
Start Page
16321
End Page
16327
DOI
10.1021/bi971182l
Show More

Research Areas:

  • Adolescent
  • Animals
  • Aspartate-Ammonia Ligase
  • Atrophy
  • Body Patterning
  • Brain
  • Brain Chemistry
  • Cell Count
  • Cell Line
  • Cell Proliferation
  • Child
  • Electroporation
  • Embryo, Mammalian
  • Exons
  • Female
  • G2 Phase Cell Cycle Checkpoints
  • Gene Deletion
  • Gene Expression Regulation, Developmental
  • Gene Targeting
  • Genetic Predisposition to Disease
  • Haploinsufficiency
  • Homozygote
  • Humans
  • Hypopigmentation
  • Image Processing, Computer-Assisted
  • In Situ Hybridization
  • Infant
  • Infant, Newborn
  • Intellectual Disability
  • Male
  • Melanocytes
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microcephaly
  • Mitosis
  • Mutation, Missense
  • Neural Crest
  • Neural Stem Cells
  • Nuclear Proteins
  • Organ Specificity
  • Pedigree
  • SOXE Transcription Factors
  • Syndrome