Elementary Events of Intracellular Calcium Signaling

描述(由申请人提供)：几乎所有类型的细胞都利用细胞内储存的钙离子释放到胞浆中作为信号机制来调节各种功能，如电兴奋、分泌、增殖和细胞死亡。改进的成像技术揭示，通过三磷酸肌醇受体/通道(IP3R)释放钙离子是不连续发生的，因为钙信号的层次涉及单通道(基础事件)和多通道的协同开放(基础事件)。这些短暂的、局部的游离[Ca~(2+)]升高是通过聚集在内质网离散功能释放部位的IP3R引起的。单个位点具有自主的信号功能，它们的活性可能通过钙离子扩散和钙离子诱导的钙释放来进一步协调，从而传播细胞内的整体钙波。因此，基础和基本事件形成了复杂的时空钙信号下的分层构建块，允许分级和选择性地调节细胞功能。因此，阐明它们的产生、相互作用和功能后果是理解普遍存在的钙信使途径的生理功能及其参与病理状态的关键。我们的总体目标是阐明细胞如何产生IP3介导的钙信号的层次结构，如何利用这些信号来对效应器反应进行特定和局部的调节，以及信号通路中的中断可能如何参与疾病。通过利用先进的生物光子学工具，包括共焦显微镜、多光子显微镜和全内反射显微镜，以及光释放的IP3，我们的目标是：(I)开发改进的光学技术，以便成像通过完整细胞内单个通道的钙离子通量。(Ii)阐明IP3R在释放部位的活动是如何被编排以产生基本的Ca2v信号的。(Iii)确定细胞内的钙缓冲如何调节释放部位之间的协调，以产生全球钙信号。(Iv)探索钙瞬变的时空模式编码特定和选择性细胞信号的原理。(V)探讨IPA/Ca~(2+)信使通路在神经元信号转导和AIzheimer病发病机制中的作用。

DESCRIPTION (provided by applicant): The liberation of Ca2+ from intracellular stores into the cytosol is used as a signaling mechanism by virtually all cell types to regulate functions as diverse as electrical excitability, secretion, proliferation and cell death. Improved imaging technology has revealed that Ca2+ liberation through inositol trisphosphate receptor/channels (IP3R) occurs discontinuously, as a hierarchy of Ca2+ signals involving single channels ('fundamental' events) and concerted openings of multiple channels ('elementary' events). These transient, localized free [Ca 2+] elevations arise through IP3R clustered at discrete functional release sites on the endoplasmic reticulum. Individual sites serve autonomous signaling functions, and their activity may further be coordinated through Ca2+ diffusion and Ca2+-induced Ca2+ release to propagate global cellular Ca2+ waves. Fundamental and elementary events thus form hierarchical building blocks underlying the complex spatiotemporal Ca2+ signals that permit graded and selective regulation of cell functions. Elucidation of their generation, interaction and functional consequences is, therefore, pivotal to understand the physiological functioning of the ubiquitous Ca2+ messenger pathway and its involvement in pathological states. Our overall goals are to elucidate how cells generate the hierarchy of IP3-mediated Ca2+ signals, how these are utilized for specific and localized regulation of effector responses, and how disruptions in the signaling pathway may be involved in disease. By utilizing advanced biophotonic tools - including confocal, multiphoton and total internal reflection microscopy, and photoreleased IP3 - we aim to: (i) Develop improved optical techniques so as to image Ca2+ flux through individual channels within the intact cell. (ii) Elucidate how the activity of IP3R at a release site is orchestrated to generate elementary Ca2v signals. (iii) Determine how cellular Ca2+ buffers modulate the coordination between release sites to generate global Ca2+ signals. (iv) Explore the principles by which spatio-temporal patterning of Ca 2+ transients encodes specific and selective cell signals. (v) Investigate the roles of the IPa/Ca2+ messenger pathway in neuronal signaling and in the pathogenesis of AIzheimer's disease.