Mechanisms Regulating Calcium Flux In Salivary Glands

唾液腺中液体分泌的神经递质刺激通过胞质[Ca-2+]的双相升高介导;由于内部释放而导致的初始瞬时增加和由于Ca-2+内流而导致的后期持续增加。持续的液体分泌被认为直接依赖于[Ca-2+]的持续升高，从而依赖于Ca-2+内流。该项目旨在了解唾液腺细胞中介导和调节Ca-2+信号的机制。近年来，我们的工作主要集中在对唾液腺细胞内Ca-2+内流的调控机制的研究上。唾液细胞中的Ca-2+内流是许多其他非兴奋细胞中存在的钙库操纵的Ca-2+内流机制的原型。这种流入的分子机制尚未在任何细胞类型中确定。最近，离子通道蛋白的瞬时受体电位（Trp）家族已被提出作为钙池操纵的Ca-2+内流通道的分子组成部分。我们以前曾报道大鼠Trp 1的克隆和鉴定和定位的内源性Trp 1蛋白在大鼠和人唾液腺细胞。在本报告期间，我们进一步研究了Trp 1在钙池操纵的Ca-2+内流机制中的作用。我们的研究表明，Trp 1是一个强有力的候选人在唾液腺细胞的Ca-2+内流通道。此外，我们已经报道，Trp 1定位于脂筏区，在那里它与其他Ca-2+信号分子，如IP 3R和G-蛋白一起组装成一个更大的信号复合物沿着。唾液腺和人唾液腺细胞系。我们建议，蛋白质-蛋白质相互作用促进在这个signaplex调节存储操作的Ca-2+内流。从我们的功能研究中，我们已经检查了钙池操纵的Ca-2+通道通过使用膜片钳方法介导的Ca-2+电流的结果，也与这些发现一致。本研究将继续关注钙池调控的Ca-2+内流途径及其在唾液腺分泌中的调节和作用。

Neurotransmitter stimulation of fluid secretion in salivary glands is mediated via a biphasic elevation in cytosolic [Ca-2+]; an initial transient increase due to internal release and a latter sustained increase due to Ca-2+ influx. Sustained fluid secretion is suggested to directly dependent upon the sustained elevation of [Ca-2+]and thus on Ca-2+ influx. This project is aimed towards understanding the mechanisms which mediate and regulate Ca-2+ signaling in salivary gland cells. Recently, our efforts have been focused on the mechanisms involved in mediating and regulating Ca-2+ influx into salivary gland cells. Ca-2+ influx in salivary cells is prototypical of the store-operated Ca-2+ influx mechanism present in many other non-excitable cells. The molecular mechanism(s) of this influx has not yet been determined in any cell type. Recently, the transient receptor potential (Trp)family of ion channel proteins have been proposed as molecular components of the store-operated Ca-2+ influx channel. We have previously reported cloning of rat Trp1 and identification and localization of the endogenous Trp1 protein in rat and human salivary gland cells. In this reporting period we have further studied the role of Trp1 in the store-operated Ca-2+ influx mechanism. Our studies suggest that Trp1 is a strong candidate for the Ca-2+ influx channel in salivary gland cells. Further, we have reported that Trp1 is localized in a lipid raft region where it is assembled in a larger signaplex along with other Ca-2+ signaling molecules, such as the IP3R and G-proteins. salivary glands and human salivary gland cell lines. We propose that protein-protein interactions facilitated within this signaplex regulate store-operated Ca-2+ influx. Results from our functional studies where we have examined the Ca-2+ current mediated by the store-operated Ca-2+ channel by using patch clamp methodology, are also consistent with these findings. Our future studies will continue to focus on the store-operated Ca-2+ influx pathway, its regulation and role in salivary gland fluid secretion.