Ca2+ and secretory dynamics in salivary acinar cells

充足的唾液分泌对口腔健康和整体健康至关重要。这是最好的赞赏下 唾液腺功能减退的情况。口干（口干症）与显著的发病率相关， 个体经历味觉的改变，吞咽和说话的问题， 口腔感染和龋齿的易感性。口干的一个主要原因是相对常见的 自身免疫性疾病，干燥综合征（SS）。SS具有较高的女性优势，并与 严重的唾液流丧失，几乎没有治疗选择。值得注意的是，在疾病晚期， 液体流动可归因于淋巴细胞浸润后的腺体破坏， 唾液腺功能明显丧失，但没有广泛的淋巴细胞受累， 完整的腺体结构。这一信息强烈表明，SS的早期事件是对 产生唾液的细胞机制。与这一想法相一致，我们最近报告说， 丰富的细胞内钙释放通道，肌醇1，4，5-三磷酸受体（IP 3R），这是 负责唾液腺中离子和液体运动的机制的中枢，在两种小鼠中均减少 模型组和SS组淋巴细胞浸润程度较低，腺体结构完整。此外，委员会还认为， 我们现在表明，在全长蛋白下调之前，IP 3R受到有限的 蛋白水解裂解。令人惊讶的是，蛋白水解切割不会使通道失效，但会显著改变通道的结构。 Ca 2+信号的时空特性。推动这一提议的核心科学前提是，IP 3R 在SS的液体分泌丧失中起关键作用。实验的目的是探索机械细节 假设首先，IP 3R蛋白水解后改变的Ca 2+信号导致不适当的激活 Ca 2+依赖性效应物对体液分泌和体内平衡以及随后IP 3R如何 最终导致长期功能减退。我们建议使用几个互补的 SS模型，包括Aec 1Aec 2 NOD和IL 14 α小鼠，以及SS疾病的小鼠模型， 由急性激活免疫系统引起。我们计划使用患者来源的 组织.为了实现这些目标，具体目标将首先研究IP 3R的机制 片段化及其对唾液腺中Ca 2+信号传导的时空特性的影响 疾病早期阶段（Aim 1）。改变的Ca 2+信号对急性激活Cl-和Ca 2+信号的影响。 以及维持体内平衡所必需的K通道和线粒体生物能量学。(Aim 2）。最后我们将 探索下调和转录改变对IP 3R蛋白水平降低的贡献。 这个项目的首要目标是获得一个机械的理解过程发生在早期， SS，认为这一知识可能最终提出新的治疗目标，用于治疗 疾病

Adequate production of saliva is essential for oral health and general well-being. This is best appreciated under conditions of salivary gland hypofunction. Dry mouth (xerostomia) is associated with significant morbidity as individuals experience an altered perception of taste, problems swallowing and speaking and an increased susceptibility to oral infections and dental caries. A major cause of dry mouth is the relatively common autoimmune disease, Sjögrens syndrome (SS). SS has a high female predominance and is associated with profound loss of salivary flow with few treatment options. Notably, while late in the disease when the loss of fluid flow can be attributed to glandular destruction following lymphocyte infiltration, patients often present with a marked loss of salivary gland function, but without extensive lymphocyte involvement and with seemingly intact glandular structure. This information suggests strongly that an early event in SS is disruption to the cellular machinery which produces saliva. Consistent with this idea, we have recently reported that the abundance of the intracellular Ca2+ release channel, the inositol 1,4,5-trisphosphate receptor (IP3R), which is central to the mechanisms responsible for ion and fluid movement in salivary glands, is reduced in both mouse models and SS patients with low grade lymphocyte involvement and intact glandular structure. Furthermore, we now shown that prior to down-regulation of the full-length protein that the IP3R is subject to limited proteolytic cleavage. Surprisingly, proteolytic cleavage does not disable the channel but markedly alters the spatiotemporal properties of the Ca2+ signal. The central scientific premise driving this proposal is that IP3R play pivotal roles in the loss of fluid secretion in SS. Experiments are designed to explore in mechanistic detail the hypothesis that first, the altered Ca2+ signal following IP3R proteolysis results in inappropriate activation of Ca2+ dependent effectors necessary for fluid secretion and homeostasis and subsequently how IP3R are downregulated ultimately resulting in long term hypofunction. We propose to use several complementary models of SS, including the Aec1Aec2 NOD and IL14α mice, together with mouse models where SS disease is induced by acutely activating the immune system. We plan to confirm major findings using patient derived tissue. To address these goals, the specific aims will first investigate the mechanisms underlying IP3R fragmentation and its impact on the spatiotemporal properties of Ca2+ signaling in salivary glands at various stages early in disease (Aim1). The consequences of the altered Ca2+ signals for both the acute activation of Cl and K channels and mitochondrial bioenergetics necessary to maintain homeostasis. (Aim 2). Finally, we will explore the contribution of downregulation and altered transcription for the reduction of IP3R protein levels. The overarching objective of this project is to gain a mechanistic understanding of processes occurring early in SS, with a view that this knowledge may ultimately suggest novel therapeutic targets for the treatment of disease.