Structural determinants and pharmacological modulation of synaptic GEFs and GAPs

SUMMARY - PROJECT 1 The goal of this Center is to understand how gene expression and associated gene function within key neuronal subtypes regulates the neurobiological substrates required to form cortical circuits that enable decision-making and behavioral adaptations (i.e., behavioral circuits). Fitting with this theme, Project 1 will investigate the biology of synaptic GEFs and GAPs at the molecular/biochemical and cellular levels. GEFs and GAPs are complex multidomain proteins with multiple splice variants. Their protein domains perform enzymatic catalysis, subcellular targeting, and autoregulation. Such domain combinatorial complexity can further specialize function to various subcellular compartments, neuronal subtypes, and developmental time-points. Project 1 will test the hypothesis that a structure-function analyses of isoforms, domains, and clinical variants will reveal mechanisms of protein regulation that underlie neuronal morphogenesis, synapse formation, and synapse plasticity. We recently developed novel high- and medium-throughput assays to characterize the modulation of GEF/GAP catalytic activity and neuronal function by single nucleotide variants and chemical probes. Using these, we will delineate GEF and GAP spatiotemporal complexity by dissecting the roles of splice variants, enzymatic domains, and non-catalytic domains at the molecular and cellular levels. Additionally, Project 1 will develop chemical probes which will be utilized to further define their biological function in Projects 2-4. Spatiotemporal and GTPase activity analyses will identify critical periods and cell/tissue specificity for biological activity and genetic and pharmacological manipulation to inform Projects 2–4. Mutation-driven structure-function analysis will reveal mechanistic insight to guide iPSC and mouse studies in Projects 2–4. Chemical probes will be highly valuable in Projects 2–4 and for the field. Data generated will reveal novel mechanism of function and regulation to provide a conceptual framework for the large family of > 180 Ras/Rho GEF/GAPs, with broad implications.