Store-operated channels in the nervous system

Northwestern University At Chicago, Evanston IL

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Abstract

DESCRIPTION (provided by applicant): Ca2+ signals regulate diverse functions in the developing nervous system, including proliferation and differentiation of neural stem cells (NSCs), migration of nascent neurons, and apoptosis. Although the role of Ca2+ signaling in the development of the nervous system is widely recognized, little is known about the mechanisms responsible for the production of Ca2+ signals in NSCs. Among the various mechanisms by which cellular Ca2+ signals are generated, store-operated Ca2+ release-activated Ca2+ (CRAC) channels have emerged as a widespread pathway for regulating many Ca2+-dependent functions, including transcription, motility and proliferation. CRAC channels are encoded by the Orai genes, which give rise to three highly homologous proteins that are widely expressed in most tissues. Emerging evidence in our laboratory indicates that CRAC channels arising from the canonical Orai1-STIM1 proteins comprise a major route of Ca2+ entry in NSCs. Moreover, we find that Ca2+ influx through CRAC channels powerfully activates Ca2+-dependent gene expression through the transcription factor, NFAT, and regulates proliferation of NSCs. We hypothesize that CRAC channels are a key checkpoint for regulating gene expression, self-renewal, and differentiation of neural progenitors. The overall thrust of the present proposal is to elucidate the molecular and functional properties of CRAC channels in NSCs and illuminate their role for gene expression, proliferation, and differentiation of NSCs. Using a powerful combination of optical, electrophysiological and biochemical approaches as well as genetically engineered mice lacking CRAC channel function, we will: 1) define the electrophysiological properties and molecular machinery of CRAC channels in NSCs, 2) investigate the physiological activators of CRAC channels in NSCs, and, 3) illuminate the downstream functions of CRAC channels for gene expression, proliferation, and lineage commitment. Findings from these studies will reveal the role of an important yet unexplored Ca2+ signaling pathway for the biology of NSCs, and facilitate strategies to develop therapeutics based on the engineering of neural stems cells for neurodegenerative diseases and brain trauma.