The development of immature T cells into mature, antigen-specific, functional T lymphocytes is central to immune defenses against pathogens. It is essential that this process be efficient, lest autoreactive T lymphocytes develop and migrate to the peripheral lymphoid system where they can mediate autoimmune disease. Class I MHC molecules present on epithelial cell surfaces play a pivotal role in the development of thymocytes. The long-term goals of the proposed studies are to elucidate the subcellular organization of thymic epithelium and to determine if a specialized distribution of MHC molecules on specific membrane domains of thymic epithelial cells plays a role in the development of thymocytes. Glycosylphosphatidylinositol (GPI)-tethered proteins are targeted to specialized membrane domains in certain cell types, including neurons and epithelial cells. A GPI-tethered class I MHC molecule has been reported to be defective in mediating the development of thymocytes whose antigen receptors are specific for that class I MHC molecule. To determine if thymic epithelium has specialized membrane domains, mutant forms of the mouse H-2Db class I MHC molecule, including a GPI-tethered form, will be generated and introduced into the germline of mice. These transgenic mice will then be mated to other transgenic mice which express a T-cell receptor specific for H-Y antigen + H-2Db to generate double transgenic mice. The development of T lymphocytes in single and double transgenic female and male mice will be analyzed. The submembranic localization of wild type and mutant H-2Db molecules will be examined to determine if a GPI tether causes a redistribution of H-2Db on the surfaces of thymic epithelial cells. Because GPI-anchored proteins also differ from wild type class I MHC molecules in terms of their trafficking to and from the cell surface, the endocytosis and recycling of wild type and mutant H-2Db molecules will be studied. Finally, since many GPI-tethered proteins have been shown to form protein complexes with tyrosine protein kinases known to be involved in signal transduction pathways, biochemical studies will be performed to determine if H-2Db-GPI molecules associate with protein kinases. These studies provide a model system for analyzing the role that the thymic architecture plays in T lymphocyte development. These studies have implications for malfunctions of the immune system such as autoimmunity and immunodeficiency diseases.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG2-ALY (01))
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Kehn, Patricia J
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University of California Santa Cruz
Schools of Arts and Sciences
Santa Cruz
United States
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