TRPC1, Calcium, and Saliva Secretion

描述(申请人提供)：唾液具有许多极其重要的生物学功能，有助于维持口腔健康。据估计，美国有500多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，钙被认为是调节液体分泌的主要细胞内因子，但参与调节胞浆钙的分子机制尚不清楚。这主要是由于缺乏关于唾液腺中存在的钙通道调节机制的信息。此外，还没有关于胞浆钙如何调节唾液分泌的信息。此外，在干燥综合征患者中，尽管腺泡组织看起来正常，但它们功能不正常，对激动剂刺激的钙反应降低。这一观察结果提出了钙通道在这种病理状态下可能发生改变的可能性。我们的获奖结果表明，TRPC1是唾液腺的主要钙通道，与唾液分泌密切相关。为了了解TRPC1通道的调节，我们已经证明在人类颌下腺细胞中，TRPC1与STIM1、Cav1和Orai1的相互作用决定了TRPC1介导的钙内流。此外，这些蛋白质-蛋白质的相互作用仅限于质膜中的特定区域，然而，目前尚不清楚在唾液腺组织中是否也存在类似的机制。因此，在这次更新中，我们打算深入研究细胞内钙在唾液腺功能中的作用，并确定瞬时受体典型电位(TRPC1)-1与唾液分泌的关系。本研究的假设是，由于通过TRPC1的钙内流在唾液腺的生理功能中起着关键作用，因此，唾液腺钙通道的特征对于了解唾液分泌的机制将是重要的，这可能作为治疗唾液腺功能障碍的药物靶点。我们将协调努力，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TRPC1通道组装/激活中的作用，并将确定通过STIM1和Orai1调控TRPC1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。更好地了解这些导致唾液分泌的事件对于阐明唾液腺功能障碍的新疗法将是重要的。 与公共健康相关：据估计，美国有500多万人患有唾液腺功能障碍。唾液腺功能丧失是许多药物的限制性副作用，是使用放射疗法治疗头颈癌的严重后果，也是自身免疫性疾病(如Sj“gren综合征)的常见后果。我们目前的研究集中在钙内流通过瞬时受体电位Canonical-1在调节唾液分泌中的作用。我们预计，阐明钙离子进入调节唾液分泌的机制将对理解唾液腺功能障碍很重要。此外，我们将确定TRPC1介导的钙内流所需的信号复合体，并确定参与调节TRPC1通道本身的机制。更好地了解这些事件不仅对了解唾液分泌很重要，而且对阐明唾液腺功能障碍的新疗法也很重要。

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. PUBLIC HEALTH RELEVANCE: It has been estimated that more than 5 million people in the US suffer from salivary gland dysfunctions. Loss of salivary gland function is a limiting side-effect of numerous drugs, serious consequences of head and neck cancer treatment using radiation therapy, and also a frequent outcome of autoimmune diseases such as Sj"gren's syndrome. Our current studies are focused on the function of calcium influx via the Transient Receptor Potential canonical-1 in modulating saliva secretion. We anticipate that elucidating the mechanism of calcium entry-mediated regulation of saliva secretion; will be important to understand salivary gland dysfunction. Furthermore, we will identify the signalplex necessary for TRPC1-mediated calcium entry and define the mechanism involved in regulating TRPC1 channel per se. Greater understanding of these events will not only be important for understanding saliva secretion, but will be important in elucidating new therapies for salivary gland dysfunctions.