Store-operated channels in the nervous system

描述（由申请人提供）：神经系统中的Ca2+信号介导多种细胞功能，包括神经递质释放，膜兴奋性和增殖。为了控制这种多功能信使介导的信号的动态特征并产生特异性，神经元被赋予了大量的离子通道、泵和细胞器，它们共同作用来塑造Ca2+信号。在这个列表中，最不容易理解的是存储操作通道（SOC）。SOCs被定义为质膜上的通道，响应内质网（ER） Ca2+的耗尽而开放，是触发Ca2+流入细胞的广泛机制。在神经系统中，已知soc影响神经递质释放和突触可塑性，并且涉及soc的异常信号与阿尔茨海默病有关。然而，人们对神经元soc的基本特性以及将储存耗尽与通道激活联系起来的机制知之甚少。这项工作的长期目标是了解神经元soc的生物物理特性、分子基础和功能组织，识别触发其激活的刺激，并阐明其激活对神经元功能的下游后果。荧光钙指示器和显微镜的最新进展为深入了解SOC激活过程的本质提供了机会。本提案的总体主旨是利用新的工具来探测神经元中存储操作的Ca2+信号网络，这是由soc和内质网组成的，并探索这种信号传导对基因表达的下游后果。我们的直接目标是：(1)使用膜片钳电生理学定义神经元soc的生物物理特性。(2)利用cameleon测量ER Ca2+信号，确定SOC激活对ER Ca2+的依赖性。这与STIM1激活的ER Ca2+依赖性相比如何？ STIM1是Ca2+传感器的候选分子，可将[Ca2+]ER的信息传递给soc。(3)研究SOCs在启动由转录因子NFAT介导的Ca2+依赖性基因表达中的作用。最近的研究表明，NFAT参与了一些基本功能，如轴突生长、神经元存活和突触可塑性。对神经系统中soc的生物物理特性、激活机制和功能的进一步了解可能最终揭示Ca2+调节神经元功能的新检查点，从而为预防和治疗阿尔茨海默病等疾病提供新的策略。

DESCRIPTION (provided by applicant): Ca2+ signals in the nervous system mediate a remarkable variety of cellular functions, including neurotransmitter release, membrane excitability, and proliferation. To control the dynamic features of the signals mediated by this multifunctional messenger and generate specificity, neurons are endowed with a large repertoire of ion channels, pumps, and cellular organelles that work together to sculpt Ca2+ signals. In this repertoire, one of the least understood is the store-operated channel (SOC). SOCs, defined as channels in the plasma membrane that open in response to depletion of Ca2+ from the endoplasmic reticulum (ER), are a widespread mechanism for triggering Ca2+ influx into the cell. In the nervous system, SOCs are known to influence neurotransmitter release and synaptic plasticity, and aberrant signaling involving SOCs is associated with Alzheimer's disease. However, very little is known about the basic properties of neuronal SOCs and the mechanisms linking store depletion to channel activation. The long-term goals of this work are to understand the biophysical characteristics, molecular basis, and functional organization of neuronal SOCs, to identify stimuli that trigger their activation, and to elucidate the downstream consequences of their activation for neuronal function. Recent advances in fluorescent calcium indicators and microscopy provide an opportunity to gain insight into the nature of the SOC activation process. The overall thrust of present proposal is to exploit new tools to probe the store-operated Ca2+ signaling network in neurons, which is comprised of SOCs and the ER, and to explore downstream consequences of this signaling for gene expression. Our immediate objectives are: (1) Define the biophysical properties of neuronal SOCs using patch-clamp electrophysiology. (2) Define the ER Ca2+-dependence of SOC activation by employing cameleon to measure ER Ca2+ signals. How does this compare to the ER Ca2+-dependence of the activation of STIM1, a candidate molecule for the Ca2+ sensor that communicates information about [Ca2+]ER to SOCs? (3) Investigate the role of SOCs in initiating Ca2+-dependent gene expression mediated by the transcription factor, NFAT. Recent work indicates that NFAT is involved in several essential functions such as axonal outgrowth, neuronal survival, and synapse plasticity. An improved understanding of the biophysical properties, activation mechanisms, and functions of SOCs in the nervous system could ultimately reveal novel check points for the regulation of neuronal function by Ca2+, leading to new strategies for the prevention and treatment of diseases such as Alzheimer's disease.