Store-operated channels in the nervous system

描述(申请人提供)：钙信号调节神经系统发育中的多种功能，包括神经干细胞(NSCs)的增殖和分化、新生神经元的迁移和细胞凋亡。虽然钙信号在神经系统发育中的作用已被广泛认识，但对神经干细胞中产生钙信号的机制知之甚少。在细胞内产生钙信号的各种机制中，钙离子释放激活的钙离子通道(CRAC)是一种广泛存在的调节钙离子依赖功能的途径，包括转录、运动和增殖。CRAC通道由Orai基因编码，产生三种高度同源的蛋白，在大多数组织中广泛表达。我们实验室的新证据表明，由规范的Orai1-STIM1蛋白产生的CRAC通道构成了神经干细胞钙离子进入的主要途径。此外，我们发现，通过CRAC通道的钙离子内流通过转录因子NFAT有效地激活了钙依赖基因的表达，并调节了神经干细胞的增殖。我们假设CRAC通道是调节基因表达、自我更新和神经前体细胞分化的关键检查点。本研究的主要目的是阐明神经干细胞中CRAC通道的分子和功能特性，阐明其在神经干细胞基因表达、增殖和分化中的作用。利用光学、电生理和生化方法的强大组合以及缺乏CRAC通道功能的基因工程小鼠，我们将：1)确定神经干细胞中CRAC通道的电生理特性和分子机制；2)研究CRAC通道在神经干细胞中的生理激活剂；以及3)阐明CRAC通道在基因表达、增殖和谱系承诺方面的下游功能。这些研究结果将揭示一个重要但尚未探索的钙信号通路在神经干细胞生物学中的作用，并促进以神经干细胞工程为基础的治疗神经退行性疾病和脑创伤的策略。

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.