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Mark  S Williams
 

Mark S Williams Ph.D.

Academic Title: Assistant Professor
Primary Appointment: Microbiology and Immunology
marwilliams@som.umaryland.edu
Location: Bio Park 310
Phone: (410) 706-8204
Fax: (410) 706-8234

Research Interests:

Cells of all species have developed evolutionarily conserved, innate responses to exogenous stressors, regulating growth and survival via changes in signal transduction and gene expression. It has become clear that, in response to stimulation of cell surface receptors by agents as diverse as angiotensin II, platelet derived growth factor (PDGF), shear stress or LDL, cells also endogenously generate intracellular oxidative stress to regulate growth and survival.

The major focus of my lab is to investigate the mechanisms by which reactive oxygen or nitrogen species affect the immune system. Our results clearly demonstrate that endogenous reactive species are produced upon T cell receptor (TcR) or Fas stimulation in cultured and primary T cells. Overexpression of specific antioxidant enzymes (catalase and superoxide dismutase) was used to define the ROS produced upon receptor stimulation and is being used to define their biologic role(s) and the molecular targets of receptor stimulated ROS generation. This production of ROS has been shown to regulate TcR-stimulated signal transduction including activation of MAPK and expression of FasL. 
Current studies are using knockout and transgenic mouse models and overexpression of dominant negative and dominant active forms of signaling molecules to define pathways regulating ROS generation. We are combining these approaches with biochemical analysis of protein phosphorylation, protein:protein interaction and oxidative modification of proteins to define the mechanisms by which ROS modulate signal transduction and gene expression. New studies are investigating how viral gene products and exogenous toxicants (including chemotherapeutic agents) alter these redox dependent signaling pathways.

Publications:

Bakdash, N. and Williams, M.S. Platelet Activation by Thrombin and Convulxin are Differentially Regulated by Reactive Oxygen Species. Manuscript Submitted. 2005.

Kwon, J., Qui, C.-K., and Williams, M.S. TcR Stimulated Generation of Reactive Oxygen Species Regulates Gads-SLP-76-ADAP via Oxidative Modification of SHP-2. The EMBO Journal. In Press. 2005.

Williams, M.S. and Henkart, P.H. Do Cytotoxic Lymphocytes Kill via Reactive Oxygen Species? Immunity. 272-4. 2005.

Williams, M.S. and Kwon, J. Invited Review - Generation of Reactive Oxygen Species in Response to T cell Receptor Stimulation. Free Radical Biology and Medicine. 37: 1144-1151. 2004.

Jackson, S. H., Devadas, S., Kwon, J. and Williams, M.S. T Cells Express a Phagocyte-type NADPH Oxidase that is Activated After TcR Stimulation. Nature Immunology. 5: 818-827. 2004.

Devadas, S., Hinshaw, J.A., Zaritskaya, L., and Williams, M.S. Fas Stimulated Generation of Reactive Oxygen Species or Exogenous Oxidative Stress Regulate Sensitivity to Fas mediated Apoptosis. Free Rad. Biol Med. 35: 648-661. 2003.

Kwon, J., Devadas, S. and Williams, M.S. T Cell Receptor Stimulated Generation of Hydrogen Peroxide Inhibits MEK-ERK Activation and lck Phosphorylation. Free Rad. Biol. Med. 35: 406-417. 2003.

Davidson, W.F., Haudenschild, C. and Williams, M.S. T Cell Receptor Ligation Triggers Novel Non-apoptotic Cell Death Pathways that are Fas-independent or Fas-dependent. J Immunol. 169: 6218-30. 2002.

Devadas, S., Zaritskaya, L., Rhee, S.G., Oberley, L.W. and Williams, M.S.. Discrete Generation of Superoxide and Hydrogen Peroxide by T Cell Receptor Stimulation: Selective Regulation of Mitogen-Activated Protein Kinase Activation and Fas Ligand Expression. J. Exp. Med. 195: 59-70. 2002.