[Ca2+]i and Secretory Dynamics in Parotid Acinar Cells

唾液对口腔健康至关重要。它对口腔粘膜的水合是必不可少的；它提供润滑剂，开始 营养消化，为口腔和上半身提供抗菌和机械保护 胃肠道。唾液流量减少(口干症)极大地影响患者的生活质量。一把钥匙 刺激唾液中的液体和蛋白质成分的促分泌剂事件是增加 细胞内游离钙浓度[Ca~(2+)]_i。这种[Ca~(2+)]_i的升高具有特定的时间和空间特征 被认为对适当地激活效应器很重要的特征 唾液分泌。乙酰胆碱和大多数其他促分泌剂的作用是代谢性的。 刺激肌醇1，4，5-三磷酸(Insps)的产生和细胞内钙离子的释放。在……里面 唾液腺泡细胞，钙信号也可以由另一种，很大程度上独立的亲离子性产生 三磷酸腺苷(ATP)激活P2X类钙离子的过程 频道。后一种机制将被预测为导致钙信号和效应器激活 具有明显的空间和时间特征。使用现代光学技术，例如数字成像， 全内反射显微镜和共聚焦显微镜结合转基因动物模型和 具体的药理学，我们将扩大在分离的唾液腺腺泡中产生的发现，以定义钙离子 通过代谢刺激的信号事件，特别是通过离子型P2X4嘌呤能刺激的信号事件 器官型腮腺切片制剂中的受体(P2X4R)刺激(目标1)。CA2+信号作为 蛋白激酶A(PKA)激活后，P2X4R的激活效果显著增强。由于流体 当PKA被激活时，分泌也会增加，这可能是生理上的相关情况。在……里面 具体目标2我们建议定义这一事件背后的分子机制。在具体目标3 a中 主要目标将是评估通过P2X4受体(P2X4R)的离子亲和性嘌呤能信号， 单独或遵循特定的药理操作是液体的有效激活剂和 胞吐分泌机制。这些研究旨在促进我们对该复合体的理解 一系列受调控的分子事件，导致体液分泌，并最终可能导致 利用残留物的生理学治疗口干症的治疗策略 功能性腺泡组织。

Saliva is vital for oral health. It is essential for the hydration of the oral mucosa; it provides lubrication, begins nutrient digestion and imparts antimicrobial and mechanical protection for the mouth and upper gastrointestinal tract. Reduced flow of saliva (xerostomia) greatly impact the quality of life of suffers. A key event in the secretagogue stimulation of both the fluid and protein component of saliva is an increase in the cytosolic free calcium concentration [Ca2+]i. This increase in [Ca2+]i has specific temporal and spatial characteristics which are thought to be important for appropriately activating effectors important for the secretion of saliva. Acetylcholine and the majority of other secretagogues act in a metabotropic manner stimulating the production of inositol 1,4,5-trisphosphate (InsPS) and the release of intracellular Ca2+. In salivary acinar cells, Ca2+ signals can also be generated by an alternative, largely independent ionotropic process following adenosine triphosphate (ATP) activation of the P2X class of Ca2+ permeable ion channels. The latter mechanism would be predicted to result in Ca2+ signals and effector activation with distinct spatial and temporal characteristics. Using contemporary optical techniques such as digital imaging, total internal reflection microscopy and confocal microscopy combined with transgenic animal models and specific pharmacology we will expand on findings generated in isolated salivary gland acini to define Ca2+ signaling events stimulated through both metabotropic and in particular through ionotropic P2X4 purinergic receptor (P2X4R) stimulation in an organotypic parotid gland slice preparation (aim 1). Ca2+ signals as a result of P2X4R activation are profoundly enhanced following protein kinase A (PKA) activation. Since fluid secretion is also enhanced when PKA is activated this may be the physiologically relevant situation. In specific aim 2 we propose to define the molecular mechanism underlying this event. In specific aim 3 a primary goal will be to assess whether ionotropic purinergic signaling through P2X4 receptors (P2X4R), either alone, or following specific pharmacological manipulation is an effective activator of the fluid and exocytotic secretion mechanism. These studies are designed to advance our understanding of the complex series of regulated molecular events which result in fluid secretion and may ultimately lead to the design of therapeutic strategies for the treatment of xerostomia based on exploiting the physiology of remaining functional acinar tissue.