Acinar Cell Biology and Pancreatic Disease

正常和病理生理状态下钙离子在调节胰腺腺泡细胞功能中的关键作用 然而，响应升高的钙离子而发生的分子变化是 很大程度上是未知的。这一建议提出了一种新的机制，通过细胞内钙调节 磷脂和相关调节蛋白在内分泌途径中的运输 腺泡细胞。钙反应热稳定蛋白(CRHSP-28)是一种关键的调控分子。 腺泡细胞的分泌途径。CRHSP-28受细胞内钙离子变化的高度调控 通过其依赖的钙离子1)调节消化酶的分泌，2)与囊泡的相互作用 蛋白Annexin VI，以及3)丝氨酸磷酸化，它触发CRHSP-28从 膜结合复合体。这项提议的主要目标是检验CRHSP- 28作为钙传感器促进和稳定腺泡细胞膜所需的关键蛋白质相互作用 贩卖人口。在特定目标1中，实验将解决CRHSP-28与膜联蛋白相互作用的概念 VI指导CRHSP-28与支持分泌功能所必需的内小体的结合。立地 针对膜联蛋白VI结合域的特定突变体将在腺泡中表达并对酶原产生影响 分泌物和膜转运被确定。特殊目标2将利用CRHSP-28突变体改变 主要的CRHSP-28磷酸化位点，丝氨酸136，以验证磷酸化抑制CRHSP-28的理论 通过将其从膜结合状态中置换出来而起作用。具体目标3将解决以下假设 CRHSP-28调节不同于酶原颗粒的顶膜转运途径和 负责将重要的调节分子穿梭到顶膜。对分子的解释 CRHSP-28调节外分泌功能的机制可以为我们提供有价值的见解。 腺泡细胞分泌途径的依赖性，这是发展的关键。 针对胰腺外分泌疾病的治疗策略。 这一建议旨在了解细胞内钙离子变化调节的生化机制。 正常和病理状态下的胰腺功能。因此，这些研究将有助于确定潜在的 以治疗胰腺疾病为目标的药物发现和治疗策略。

The pivotal role of Ca2+ in regulating pancreatic acinar cell function under normal and pathophysiological conditions is well established, however, the molecular changes that occur in response to elevated Ca2+ are largely unknown. This proposal addresses a novel mechanism by which cytosolic Ca2+ modulates the trafficking of phospholipids and associated regulatory proteins in the secretory and endocytic pathways in acinar cells. Calcium responsive heat-stable protein (CRHSP-28) is a key regulatory molecule in the secretory pathway of acinar cells. CRHSP-28 is highly modulated by changes in cellular Ca2+ as indicated by its Ca2+-dependent 1) regulation of digestive enzyme secretion, 2) interaction with the vesicletrafficking protein annexin VI, and 3) serine phosphorylation, which triggers the release of CRHSP-28 from a membrane associated complex. The primary objective of this proposal is to test the hypothesis that CRHSP- 28 acts as Ca2+-sensor to promote and stabilize key protein interactions necessary for acinar cell membrane trafficking. In Specific Aim 1 experiments will address the concept that interaction of CRHSP-28 with annexin VI directs CRHSP-28 association with endosomes that are necessary to support secretory function. Site specific mutants targeting the annexin VI binding domain will be expressed in acini and effects on zymogen secretion and membrane trafficking determined. Specific Aim 2 will utilize CRHSP-28 mutants that alter the major CRHSP-28 phosphorylation site, serine 136, to test the theory that phosphorylation inhibits CRHSP-28 function by displacing it from a membrane-bound state. Specific Aim 3 will address the hypothesis that CRHSP-28 regulates an apical membrane trafficking pathway that is distinct from zymogen granules and acts to shuttle important regulatory molecules to the apical membrane. Elucidation of the molecular mechanism by which CRHSP-28 modulates exocrine function should provide valuable insight into the.Ca2+- dependent nature of the secretory pathway in acinar cells, which is essential for the development of therapeutic strategies aimed at the treatment of exocrine pancreatic disease. This proposal is aimed at understanding the biochemical mechanism by which changes in cell Ca2+ regulate pancreatic function in normal and pathological states. As such, these studies will help to identify potential targets for drug discovery and therapeutic strategies ajmed at treating pancreatic disease.