Mechanisms of IP3-dependent Ca++ homestasis regulation

描述(申请人提供)：钙(钙)是一种普遍存在的细胞内信号，负责控制许多细胞过程。这项建议侧重于利用线虫分子遗传学的力量来理解钙离子的稳态调节。这项建议旨在研究细胞间钙波传播和存储操作的钙(SOC)通道的功能和机制，这是肌醇1，4，5-三磷酸(IPS)依赖途径的一部分。细胞间钙波的传播在许多不同物种的各种细胞类型中都可以观察到。有人提出，细胞间的钙波在特定的器官中起着同步细胞活动的作用。我们首次观察到线虫肠道细胞内钙波的传播，但其功能尚不清楚。由于细胞内钙波的传播是一种被广泛观察到的生物学现象，这可能成为利用遗传学研究其机制和功能的重要模型系统。在细胞内钙库耗尽时，SOC通道对细胞外液中的钙摄取具有重要作用。推测SOC内流在神经信号转导和某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起重要作用。尽管SOC通道在生物学和临床上具有重要意义，但它们的分子同一性仍存在很大争议。我们将检验这一假设，即任何瞬时受体电位通道都与线虫肠道中的SOC活动有关。为了研究钙稳态，我们开发了一种结合遗传学、钙成像和电生理方法的独特的检测系统。该系统的这种独特性可能有助于揭示钙离子稳态调节机制的新方面，这些方面在其他系统中无法很好地解决。利用这一检测系统，我们将解决以下三个问题：1)研究细胞间钙波传播的功能；2)利用反向遗传学鉴定细胞内操纵的钙通道；3)利用正向遗传学分离影响钙稳态的突变。第二个和第三个目标将相辅相成，以确定调节钙稳态的重要分子。该项目的完成将为研究由钙离子稳态异常引起的人类疾病提供新的见解。

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.