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。唾液的分泌由许多离子通道和转运蛋白的协同活动驱动。尽管钙被认为是调节液体分泌的主要细胞内因子，但涉及胞质钙调节的分子机制尚不清楚。这主要是由于缺乏有关唾液腺中钙通道调节机制的信息。此外，没有关于细胞溶质钙的增加如何调节唾液分泌的信息。此外，在干燥综合征患者中，虽然腺泡组织看起来是正常的，但它们不能正常发挥功能，并且对激动剂刺激的钙反应降低。这一观察结果提出了在这种病理条件下钙通道可能改变的可能性。从我们获得的资助获得的结果表明，TRPC 1是唾液腺中的主要钙通道，并密切参与唾液分泌。为了理解TRPC 1通道的调节，我们已经表明，在人下颌下腺细胞中，TRPC 1与STIM 1，Cav 1和Orai 1的相互作用决定了TRPC 1介导的钙离子内流。此外，这些蛋白质-蛋白质相互作用仅限于质膜中的特定结构域，然而，如果类似的机制也存在于唾液腺组织中，则一无所知。因此，在这次更新中，我们打算彻底表征细胞溶质钙在唾液腺功能中的作用，并确定瞬时受体电位典型（TRPC 1）-1和唾液分泌之间的关系。本研究的假设是，由于通过TRPC 1的钙内流在唾液腺的生理功能中起着关键作用，因此唾液腺中钙通道的表征对于理解唾液分泌机制将是重要的，这可能代表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TRPC 1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TRPC 1通道的组装/激活中的作用，并将确定通过STIM 1和Orai 1调节TRPC 1的机制。我们的研究结果有望为钙通道的作用和参与唾液分泌的分子机制提供新的见解。更好地了解这些事件负责唾液分泌将是重要的，阐明新的治疗唾液腺功能障碍。

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.