Francis Ka-Ming Chan

Overview:

Our lab is interested in how cell death impacts innate inflammation and immune responses.  We have a long-standing interest in the biology and signaling mechanism of tumor necrosis factor (TNF), a key cytokine that regulates many inflammatory diseases (e.g. rheumatoid arthritis, inflammatory bowel diseases etc), pathogen infections, and cancer.  Several key discoveries made by the PI during his graduate school and postdoctoral training include identification of one of the first cell cycle inhibitors, INK4d-p19 (Mol Cell Biol. 1995, cited over 300 times), and the discovery of the "pre-ligand assembly domain (PLAD)" that mediates TNF receptors signal transduction (Science 2000, cited over 800 times).

In recent years, we have focused our effort on elucidating the signaling mechanism of a novel form of inflammatory cell death termed necroptosis.  In 2009, our group identified Receptor Interacting Protein kinase 3 (RIPK3) as a central mediator of necroptosis (Cell, 2009, cited over 1000 times).  Current projects include (1) deciphering the signaling mechanisms of necroptosis, (2) interrogation of the biology of RIPK3 and related necroptosis signaling molecules in intestinal wound healing and inflammation, (3) elucidation of the role of necroptosis in pathogen infections, and many others. 

We aim to take the knowledge we gain from basic pathway discovery to better understand the principles of immune regulation.  We believe our endeavor will pave the way for more efficacious therapeutic intervention in auto-inflammatory diseases, cancers and pathogen infections.

Current research projects in the lab include the following broad areas.  Interested students and postdoctoral candidates are encouraged to contact Dr. Chan for more information on rotation projects and research opportunities.

1. The role of necroptosis signal adaptors in inflammatory diseases
We are interested in how the kinases RIPK1 and RIPK3, both of which have critical functions in cell death, contribute to injury-induced inflammation and tissue repair.  Currently, we are using mouse models of intestinal injury and inflammation to study the function of these signal adaptors in intestinal homeostasis.

2. The role of cell death in anti-viral immune responses
We have discovered that necroptosis is an important innate immune defense mechanism against certain viruses.  We are interested in how host cell death during pathogen infections can alter the course of the host immune response.  On the other hand, we are also interested in exploring the mechanisms employed by different viral pathogens in combating the host cell death machinery.

3. Signaling mechanism of RIP kinases in cell death and inflammation
We found that the RIP kinases can promote inflammation through cell death-dependent and independent mechanisms.  What are the molecular events that regulate the diverse functions of the RIP kinases?  We are using biochemical, cell biological, and genetic tools to dissect the molecular regulation of these important immune signaling molecules.

Positions:

Professor of Immunology

Immunology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 1996

University of California - Berkeley

Grants:

Necroptosis signaling adaptors in inflammatory diseases

Administered By
Immunology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Viral mechanisms of necroptosis evasion

Administered By
Immunology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Viral inhibition of cell death in host immune responses

Administered By
Immunology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Viral inhibition of cell death in host immune responses

Administered By
Immunology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Publications:

TNF, cell death and inflammation

Tumor necrosis factor (TNFα) is a pleiotropic cytokine that mediates diverse biological responses. In the immune system, TNFα facilitates many aspects of immune responses against pathogenic challenges. While TNFα plays a critical role in the immune defense against pathogens, hyper-activation of the TNFα signaling cascade often results in the development of inflammatory and autoimmune diseases. Examination of natural mutations in human and experimental mouse models that affect TNFα-TNF receptor interaction or their downstream signaling components confirm the importance of this cytokine /receptor pair in the inflammatory process and immunity. Blockade of TNF-TNF receptor interaction has been highly successful in treating several autoimmune diseases including rheumatoid arthritis and Crohn's disease. The pro-inflammatory effects of TNFα can be achieved through several distinct signaling mechanisms including the activation of NF-κB and programmed cell death. In this review, we discuss recent advances in our understanding of the mechanisms by which TNFα induces different forms of programmed cell death and the role they play in mediating the inflammatory response. Specifically, we discuss how the induction of a recently defined cell death pathway, programmed necrosis, by TNFα may contribute to the activation of innate immune responses and the inflammatory process. © 2005 Bentham Science Publishers Ltd.
Authors
Bixby, J; Ray, TD; Chan, FKM
MLA Citation
Bixby, J., et al. “TNF, cell death and inflammation.” Current Medicinal Chemistry: Anti Inflammatory and Anti Allergy Agents, vol. 4, no. 6, Jan. 2005, pp. 557–67. Scopus, doi:10.2174/156801405774933214.
URI
https://scholars.duke.edu/individual/pub1498616
Source
scopus
Published In
Current Medicinal Chemistry: Anti Inflammatory and Anti Allergy Agents
Volume
4
Published Date
Start Page
557
End Page
567
DOI
10.2174/156801405774933214

RIPK1-RIPK3-MLKL-Associated Necroptosis Drives Leishmania infantum Killing in Neutrophils.

Necroptosis is a pro-inflammatory cell death, which happens in the context of caspase-8 inhibition, allowing activation of the receptor interacting protein kinase 1-receptor interacting protein kinase 3-mixed lineage kinase domain-like (RIPK1-RIPK3-MLKL) axis. Recently, necroptosis has emerged as a key component of resistance against pathogens including infected macrophage by Leishmania infantum, the ethiologic agent of Visceral leishmaniasis (VL). VL is the most severe form of Leishmaniasis, characterized by systemic inflammation and neutropenia. However, the role of neutrophil cell death in VL has not been characterized. Here, we showed that VL patients exhibited increased lactate dehydrogenase levels in the serum, a hallmark of cell death and tissue damage. We investigated the effect of necroptosis in neutrophil infection in vitro. Human neutrophils pretreated with zVAD-fmk (pan-caspase inhibitor) and zIETD-fmk (caspase-8 inhibitor) increased reactive oxygen species (ROS) level in response to Leishmania infection, which is associated with necroptotic cell death. MLKL, an important effector molecule downstream of necroptosis pathway, was also required for Leishmania killing. Moreover, in absence of caspases-8, murine neutrophils displayed loss of membrane integrity, higher levels of ROS, and decreased L. infantum viability. Pharmacological inhibition of RIPK1 or RIPK3 increased parasite survival when caspase-8 was blocked. Electron microscopy assays revealed morphological features associated with necroptotic death in L. infantum infected-neutrophils pretreated with caspase inhibitor, whereas infected cells pretreated with RIPK1 and RIPK3 inhibitors did not show ultra-structural alterations in membrane integrity and presented viable Leishmania within parasitophorous vacuoles. Taken together, these findings suggest that inhibition of caspase-8 contributes to elimination of L. infantum in neutrophils by triggering necroptosis. Thus, targeting necroptosis may represent a new strategy to control Leishmania replication.
Authors
Barbosa, LA; Fiuza, PP; Borges, LJ; Rolim, FA; Andrade, MB; Luz, NF; Quintela-Carvalho, G; Lima, JB; Almeida, RP; Chan, FK; Bozza, MT; Borges, VM; Prates, DB
MLA Citation
Barbosa, Laiana A., et al. “RIPK1-RIPK3-MLKL-Associated Necroptosis Drives Leishmania infantum Killing in Neutrophils.Front Immunol, vol. 9, 2018, p. 1818. Pubmed, doi:10.3389/fimmu.2018.01818.
URI
https://scholars.duke.edu/individual/pub1489400
PMID
30154785
Source
pubmed
Published In
Frontiers in Immunology
Volume
9
Published Date
Start Page
1818
DOI
10.3389/fimmu.2018.01818

Editorial

Authors
MLA Citation
Chan, F. K. M. “Editorial.” Current Medicinal Chemistry: Anti Inflammatory and Anti Allergy Agents, vol. 4, no. 6, Jan. 2005, p. 555. Scopus, doi:10.2174/156801405774933179.
URI
https://scholars.duke.edu/individual/pub1498619
Source
scopus
Published In
Current Medicinal Chemistry: Anti Inflammatory and Anti Allergy Agents
Volume
4
Published Date
Start Page
555
DOI
10.2174/156801405774933179

Flow cytometric analysis of fluorescence resonance energy transfer: a tool for high-throughput screening of molecular interactions in living cells.

The study of cellular processes has been facilitated by the use of methods to detect molecular associations both in vivo and in vitro. An invaluable tool to study molecular associations associated with dynamic processes in living cells utilizes the phenomenon of fluorescence resonance energy transfer (FRET), together with selected fluorophores that are attached to molecules of interest. Many reports have utilized fluorophores conjugated to antibodies for FRET pairs. However, these methods are restricted to extracellular molecules and dependent upon the availability of appropriate antibodies. The recent development of green fluorescent protein (GFP) variants suitable for FRET has expanded the utility of this methodology by permitting the study of intracellular as well as extracellular processes. Combining FRET with flow cytometric analysis results in a powerful high-throughput assay for molecular associations. This article details the use of green fluorescent protein (GFP) mutants cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) to measure the association of the signaling component TRAF2 with the TNFR-2 receptor to illustrate the versatility of this methodology.
Authors
Chan, FK-M; Holmes, KL
MLA Citation
Chan, Francis Ka-Ming, and Kevin L. Holmes. “Flow cytometric analysis of fluorescence resonance energy transfer: a tool for high-throughput screening of molecular interactions in living cells.Methods in Molecular Biology (Clifton, N.J.), vol. 263, Jan. 2004, pp. 281–92. Epmc, doi:10.1385/1-59259-773-4:281.
URI
https://scholars.duke.edu/individual/pub1498614
PMID
14976372
Source
epmc
Published In
Methods in Molecular Biology (Clifton, N.J.)
Volume
263
Published Date
Start Page
281
End Page
292
DOI
10.1385/1-59259-773-4:281

Programmed necrosis/necroptosis: An inflammatory form of cell death

It was not long ago when necrosis was thought to be cell injury caused by nonspecific physical trauma. In recent years, a dedicated pathway that triggers necrosis in response to TNF-like death cytokines, certain toll-like receptors, and in response to viral pathogens was described. Signaling adaptors that contain the RIP homotypic interaction motif (RHIM), such as receptor interacting protein kinase (RIPK) 1 and RIPK3, are key inducers for this form of regulated necrosis, often referred to as programmed necrosis or necroptosis. Genetic and biochemical experiments show that RIP kinase-dependent necrosis and caspase-dependent apoptosis are intimately linked. Unlike apoptosis, necrosis tends to promote inflammation. Emerging evidence indicates that the pro-inflammatory nature of necrosis is a critical driver in a wide range of disease pathologies. In this chapter, I discuss the molecular pathway that controls necrosis and how it contributes to different inflammatory diseases.
Authors
MLA Citation
Chan, F. K. M. “Programmed necrosis/necroptosis: An inflammatory form of cell death.” Cell Death: Mechanism and Disease, vol. 9781461493020, 2014, pp. 211–28. Scopus, doi:10.1007/978-1-4614-9302-0_10.
URI
https://scholars.duke.edu/individual/pub1498611
Source
scopus
Volume
9781461493020
Published Date
Start Page
211
End Page
228
DOI
10.1007/978-1-4614-9302-0_10