ETHANOL AND INTRACELLULAR SIGNAL TRANSDUCTION

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This is a proposal for a KO-5 Senior Scientist Award. The candidate, Raphael Rubin, M.D., is a Professor in the Dept. of Pathology, Thomas Jefferson University. Dr. Rubin has a longstanding alcohol research program that investigates the effects of alcohol on intracellular signaling processes. These studies have been performed within the environment of the Thomas Jefferson University Alcohol Research Center. He has been funded continuously by the NIAAA for 15 years with RO-1 and career development awards. The KO-5 award would allow the candidate to dedicate most of his time to alcohol research by providing substantial relief from administrative and clinical responsibilities. The overall focus of Dr. Rubin's current studies is the effect of ethanol on tyrosine kinase receptor signaling. Ethanol inhibits IGF-IR tryosine autophosphorylation and subsequent signaling events resulting in the inhibited cell proliferation and enhancement of apoptosis. This proposal reviews currently funded studies designed to assess molecular and functional aspects of the interaction of ethanol with the IGF-I signaling pathway. It is hypothesized that ethanol interferes with the tyrosine kinase activity residing within the cytoplasmic beta domain of the IGF-IR. Studies will determine the effect of ethanol on the tyrosine kinase activity of purified IGF-IR in vitro, and on the phosphorylation of specific tyrosines. Ethanol-sensitive sites on the IGF-IR beta domain will be functionally mapped by site-directed mutagenesis. The consequences of the ethanol-IGF-IR interaction for apoptosis will be assessed in murine fibroblasts and neuroglial cell lines. The enhancement of apoptosis by ethanol will be correlated with the expression of IGF-IR and its proximal signal mediators. A novel functional expression cDNA cloning approach will be used to determine the effect of ethanol on IGF-I-inducible survival gene expression. Additional studies have also demonstrated cross-talk pathways in cerebellar granule cells between NMDA and IRS-1 signaling pathways. Future studies are designed to further assess the mechanism of NMDA-induced IRS-1 action, and to evaluate the role of the IGF-IR in NMDA neuroprotection.