T-cell growth factor pathways and immune modulation

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EXCEED THE SPACE PROVIDED. Organ failure associated with aging and advanced diabetes mellitus as well as severe autoimmune and inflammatory diseases represent severe medical problems. Despite major progress, achieving effective immunosuppression and long-term graft survival remains a serious obstacle that is complicated by their extreme side effects and toxicities associated with these first and second generation immunosuppressants including cyclosporine A and FK506. It is therefore essential to explore novel molecular aspects of T-cell activation and expansion so that safe and effective therapeutic strategies can be designed. Whereas cyclosporJne targets T-cell receptor activation, several lines of evidence now justify a critical investigation of the later phase of T cell activity that is driven by interleukin-2 (IL2) family cytokines as new molecular targets for immune suppression. In this application, we present extensive and compelling preliminary data suggesting that pharmacological inhibition of IL2-induced Stat5 phosphorylation is remarkably effective against allograft rejection in animal models. The objective of this application is to investigate the effector pathways that regulate Stat5a/b activation and the genes they target. The principal hypothesis to be tested is that active Stat5 transcription factors are critical for T cell modiated immunity, and that in addition to the Jak3 tyrosine kinase, a yet-to-be identified Stat5 serine kinase is also imporotant for mediating T cell responses. To accomplish the objective of this proposal, we will pursue three specific aims to 1) Determine the role that early and late phase T-cell surface receptors regulate Stat5a/b activation, 2) Functionally characterize and identify the 80 kDa proline-directed Stat5 serine kinase; and 3) Identify Stat5 target genes in human T cells using a genome-wide technology for trapping Stats response elements. This work is important, and may significantly advance the field by providing direct molecular rationale and preclinical evidence for a new immunosuppressive strategy that could replace or complement current treatments. PERFORMANCE SITE ========================================Section End===========================================