Mechanisms of IP3-dependent Ca++ homestasis regulation

描述（由申请人提供）：钙（Ca2+）是一种普遍存在的细胞内信号，它负责控制许多细胞过程。该建议的重点是利用秀丽隐杆线虫分子遗传学的力量来理解Ca2+稳态调节。这一建议是针对细胞间Ca +波传播和存储操作的Ca2+ (SOC)通道的功能和机制的研究，这是肌醇1,4,5-三磷酸（IPS）依赖途径的一部分。细胞间Ca2+波的传播是在许多不同物种的多种细胞类型中观察到的。有人提出，细胞间Ca2+波的功能是同步细胞活动在一个特定的器官。我们首次观察到秀丽隐杆线虫肠道细胞间Ca2+波的传播，但其功能尚不清楚。由于细胞间Ca2+波传播是一种广泛观察到的生物现象，这可以成为利用遗传学研究其机制和功能的重要模型系统。SOC通道在细胞内Ca2+储存耗尽时从细胞外溶液中摄取Ca2+具有重要功能。推测SOC内流在神经信号传导和一些神经退行性疾病的发病机制中具有重要作用：SOC内流可能在阿尔茨海默病的早期发展中发挥重要作用。尽管SOC通道具有重要的生物学和临床意义，但它们的分子特性仍存在很大争议。我们将测试任何瞬时受体电位通道都负责秀丽隐杆线虫肠道SOC活性的假设。为了研究Ca2+稳态，我们通过结合遗传、Ca2+成像和电生理方法开发了一种独特的分析系统。该系统的这种独特性可能有助于揭示Ca2+稳态调节机制的新方面，这些机制在其他系统中无法很好地解决。使用该检测系统，我们将解决以下三个问题：1)研究细胞间Ca2+波传播的功能，2)使用反向遗传学识别存储操作的Ca2+通道，以及3)使用正向遗传学分离影响Ca2+稳态的突变。第二个和第三个目标将相互补充，以确定Ca2+稳态调节的重要分子。该项目的完成将为人类疾病提供新的见解，这些疾病是由异常Ca2+稳态引起的。

DESCRIPTION (provided by applicant): Calcium (Ca2+) is a ubiquitous intracellular signal, which is responsible for controlling numerous cellular processes. This proposal focuses on understanding of Ca2+-homeostasis regulation using the power of C. elegans molecular genetics. This proposal is directed toward an investigation of functions and mechanisms of the intercellular Ca +-wave propagation and the store-operated Ca2+ (SOC) channels, which are part of the inositol 1,4,5-trisphosphate (IPS)-dependent pathway. The intercellular Ca2+-wave propagation is observed in a variety of cell types in many different species. It has been proposed that the intercellular Ca2+ waves function as synchronizing cellular activities in a particular organ. We first observed the intercellular Ca2+-wave propagation in C. elegans intestine, but its function is not known at all. Since intercellular Ca2+-wave propagation is a widely observed biological phenomena, this can be an important model system to investigate its mechanism and function using genetics. The SOC channels have an important function for Ca2+ uptake from the extracellular solution upon depletion of intracellular Ca2+ stores. It is speculated that the SOC influx has an important function for neural signaling and the pathogenesis of some neurodegenerative diseases: SOC influx may play an important role in the early development of Alzheimer's disease. Despite the biological and clinical importance of the SOC channels, their molecular identity is highly controversial. We will test the hypothesis that any transient receptor potential channels are responsible for the SOC activity in the C. elegans intestine. To study Ca2+ homeostasis, we developed a unique assay system by combining genetic, Ca2+-imaging, and electrophysiological approaches. This uniqueness of the system could contribute to revealing new aspects in the regulatory mechanisms of Ca2+ homeostasis, which were not able to be addressed well in other systems. Using this assay system, we will address the following three issues 1) investigating the function of the intercellular Ca2+-wave propagation, 2) identifying the store-operated Ca2+ channels using reverse genetics, and 3) isolation of mutations that affect Ca2+ homeostasis using forward genetics. The second and third aims will complement each other to identify important molecules for regulation of Ca2+ homeostasis. Completion of this project will provide new insights into human disorders that are caused by abnormal Ca2+ homeostasis.