TRPC1, Calcium, and Saliva Secretion

描述（由申请人提供）：唾液具有许多极其重要的生物功能，有助于维持口腔健康。据估计，美国有超过500万人患有唾液腺功能障碍。唾液的分泌是由许多离子通道和转运体的协同活动驱动的。虽然认为钙是调节体液分泌的主要细胞内因子，但胞质钙调控的分子机制尚不清楚。这主要是由于缺乏关于唾液腺钙通道调节机制的信息。此外，没有关于胞质钙增加如何调节唾液分泌的信息。此外，在Sj"gren's综合征患者中，尽管腺泡组织看起来正常，但它们不能正常工作，并且对激动剂刺激的钙反应降低。这一观察结果提出了钙通道可能在这种病理状态下发生改变的可能性。我们获得的研究结果表明，TRPC1是唾液腺的主要钙通道，与唾液分泌密切相关。为了理解TRPC1通道的调控，我们已经证明，在人颌下腺细胞中，TRPC1与STIM1、Cav1和Orai1的相互作用决定了TRPC1介导的钙进入。此外，这些蛋白-蛋白相互作用局限于质膜的特定区域，然而，在体内唾液腺组织中是否也存在类似的机制尚不清楚。因此，在本次更新中，我们打算彻底表征细胞质钙在唾液腺功能中的作用，并确定瞬时受体电位规范(TRPC1) -1与唾液分泌之间的关系。本研究的假设是，由于钙通过TRPC1内流在唾液腺的生理功能中起着关键作用，因此唾液腺钙通道的表征对了解唾液分泌机制具有重要意义，可以作为唾液腺功能障碍的药物靶点。我们将协调我们的努力，以确定TRPC1通道在调节唾液分泌中的功能意义。我们还将研究脂筏在小鼠颌下腺细胞中TRPC1通道的组装/激活中的作用，并将确定通过STIM1和Orai1调节TRPC1的机制。我们的研究结果有望为钙通道的作用和唾液分泌的分子机制提供新的见解。更好地了解这些与唾液分泌有关的事件，将对阐明唾液腺功能障碍的新疗法具有重要意义。

DESCRIPTION (provided by applicant): Saliva performs a number of extremely important biological functions that are instrumental in maintaining oral health. It has been estimated that more than 5 million people in the US suffers from salivary gland dysfunction. Secretion of saliva is driven by concerted activities of a number of ion channels and transporters. Although, it is believed that calcium is the primary intracellular factor that regulates fluid secretion, the molecular mechanism involved in the regulation of cytosolic calcium is not clearly understood. This is primarily due to the lack of information regarding the mechanism of regulation of calcium channels present in salivary glands. Furthermore, no information is available as how increase in cytosolic calcium modulates saliva secretion. Moreover, in Sj"gren's syndrome patients, although the acinar tissues appear to be normal, they do not function properly and have a decreased calcium response to agonist-stimulation. This observation raises the possibility that calcium channels might be altered in this pathological condition. Results obtained from our awarded grant indicate that TRPC1 is the primary calcium channel in salivary glands and is intimately involved saliva secretion. To understand the regulation of TRPC1 channel we have shown that in human submandibular gland cells, TRPC1 interaction with STIM1, Cav1, and Orai1 dictates TRPC1 mediated calcium entry. Furthermore, these protein-protein interactions were confined to specific domains in the plasma membrane, however nothing is known if similar mechanisms are also present in vivo in salivary gland tissues. Therefore, in this renewal we intend to thoroughly characterize the role of cytosolic calcium in salivary gland function and to determine the relationship between transient receptor potential canonical (TRPC1) -1 and saliva secretion. The hypothesis of this study is that because calcium influx via TRPC1 plays a pivotal role in the physiological function of salivary glands, characterization of calcium channels in salivary glands will be important to understand the mechanism of saliva secretion, which could represent as drug targets in salivary gland dysfunction. We will coordinate our efforts in order to determine the functional significance of TRPC1 channel in regulating saliva secretion. We will also investigate the role of lipid rafts in the assembly/activation of the TRPC1 channel in mouse submandibular gland cells and will identify the mechanism involved in the regulation of TRPC1 via STIM1 and Orai1. The results of our studies are expected to provide new insights into the role of calcium channels and the molecular mechanism involved in saliva secretion. Greater understanding of these events responsible for saliva secretion will be important in elucidating new therapy for salivary gland dysfunctions.