Role of store-operated Ca entry mechanism in signal transduction in gastrointestinal intrinsic neurons

本研究的目的是确定胃肠内源性神经元的电容性钙离子内流的调节机制。为此，我们分析了电容性钙内流的特性及其与细胞内信使和可能的通道分子的调节机制。1)建立了单个培养的胃肠道内源性神经元钙信号的可视化实验系统。2)ATP通过释放细胞内钙，激活大鼠胃肠道内源性神经元的电容性钙内流和P2X2通道，从而引起细胞内钙的增加。3)缓激肽通过激活胃肠神经胶质细胞分泌的PGE2受体，引起胃肠内源性神经元钙离子浓度升高。4)在PC12细胞中表达的TRPC5通道可作为钙通道与GTP结合蛋白受体偶联。5)克隆了TRPV1的互补DNA，并在HEK293细胞中高效表达。我们发现TRPV1通道是具有高钙通透性的多通道受体通道。这些结果表明，电容性钙通道在胃肠内源性神经元的功能性钙通道中起作用，该通路受多种内在因素如三磷酸腺苷和缓激肽的调节。克隆的TRPC5和TRPV1构成了细胞内钙信号调节的钙通道。

The aim of this project was to identify the regulatory mechanisms of capacitative Ca entry in gastrointestinal intrinsic neurons. For these purposes, we analyzed the properties of capacitative Ca entry, its regulatory mechanisms with intracellular messengers and putative channel molecules. 1) We established experimental system for visualization of Ca signaling in single cultured gastrointestinal intrinsic neurons. 2) ATP elicited Ca increases through release of Ca from intracellular stores, the activation of capacitative Ca entry and P2X2 channels in rat cultured gastrointestinal intrinsic neurons. 3) Bradykinin evoked the elevation of Ca through B2 receptor activation on gastrointestinal intrinsic neurons via PGE2 secreted from enteric glial cells. 4) Cloned TRPC5 channels expressed in PC12 cells functioned as Ca entry channels coupled with GTP-binding protein receptors. 5) Complimentary DNA for TRPV1 was cloned and was hetelogeously expressed in HEK293 cells. We revealed that TRPV1 channels functioned as polymodal receptor channels with high Ca permeability. These results indicate that capacitative Ca entry channels play a role for functional Ca entry pathways in gastrointestinal intrinsic neurons, which are regulated by various intrinsic factors such as ATP and bradykinin. Cloned TRPC5 and TRPV1 constitute Ca entry channels for regulation of intracellular Ca signallings.