Calcium and Pancreatic Stimulus-Secretion Coupling

钙和胰腺刺激分泌耦合

基本信息

批准号：
7337622
负责人：
JOHN A WILLIAMS
金额：
$ 28.54万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
1989
资助国家：
美国
起止时间：
1989-01-01 至 2010-11-30
项目状态：
已结题

项目摘要

The overall aim of this research is to understand how regulatory neurotransmitters and gastrointestinal hormones act through changes in intracellular free Ca2+ to bring about digestive enzyme secretion by pancreatic acinar cells. This proposal focuses on the mechanisms involved in the terminal steps in secretion culminating in exocytosis. Using a proteomics discovery strategy, we have identified a number of small GTP binding proteins on the zymogen granule including RabSD, Rab6, Rab11, Rab27B and Rap1. Since Rabs are believed to regulate vesicular trafficking by organizing and regulating effector proteins the focus of this work includes two of these Rab molecules, RabSD and Rab27B as well as Rap1.Two other small G proteins, Rho and Rac which regulate the actin cytoskeleton will also be studied. The overall goal is to determine the role of each of these G proteins in the series of sequential processes by which zymogen granules are brought to the apical membrane, become fusion competent and undergo exocytosis. Specific aims of this proposal include: 1) What is the extent of activation (GTPliganded form) of Rab27B andRap1 on zymogen granules and is it increased by secretagogues such as cholecystokinin (CCK) and acetylcholine? Is Rap1important for secretion as has been shown for RabSD and 27B? Does Rap1 activation mediate the secretory stimulation by cyclic AMP? 2) What are the GEFs or other regulatory protein involved in activating the three granule small G proteins, Rho and Rac? Are they activated by specific heterotrimeric G proteins and/or by intracellular messengers such as Ca2+? Is a cyclic AMP activated GEF (Epac) involved in activating Rap1? 3) What are the downstream effector proteins for RabSD, Rab27B and Rap1? Are linker proteins of the Sip or Slac families involved? Is there a relation of specific small G proteins to myosin Vc? to Noc2? Which small G proteins directly or indirectly regulate SNARE complexes? This work will lead to better molecular understanding of the regulation of digestive enzyme secretion in acinar cells and potential sites for the pathological regulation that occurs in experimental pancreatitis. Relevance to public health: the pancreas is the major organ that secretes digestive breakdown of food and assimilation of nutrients. If these enzymes are not inflammatory disease pancreatitis can result. The present work is directed at understanding of the proteins involved in normal digestive enzyme secretion.

这项研究的总体目标是了解调节神经递质和胃肠道如何激素通过细胞内游离Ca2+的变化而发挥作用，从而引起消化酶的分泌胰腺腺泡细胞。该提案重点关注分泌最终步骤所涉及的机制最终导致胞吐作用。使用蛋白质组学发现策略，我们已经鉴定了许多小 GTP 酶原颗粒上的结合蛋白包括 RabSD、Rab6、Rab11、Rab27B 和 Rap1。自从拉布斯据信通过组织和调节效应蛋白来调节囊泡运输，这是本研究的重点工作包括其中两个 Rab 分子，RabSD 和 Rab27B 以及 Rap1。另外两个小 G 调节肌动蛋白细胞骨架的蛋白质 Rho 和 Rac 也将被研究。总体目标是确定每个 G 蛋白在一系列连续过程中的作用，酶原通过这些过程颗粒被带到顶膜，变得具有融合能力并进行胞吐作用。具体的该提案的目的包括： 1) Rab27B 和 Rap1 的激活程度（GTPliganded 形式）是多少酶原颗粒上的酶原颗粒是否会通过胆囊收缩素 (CCK) 等促分泌剂和乙酰胆碱？ Rap1 对于分泌是否重要，如 RabSD 和 27B 所示？说唱1吗激活介导环磷酸腺苷的分泌刺激？ 2) 什么是 GEF 或其他监管机构参与激活三种颗粒小 G 蛋白 Rho 和 Rac？它们是否被激活特定异源三聚体 G 蛋白和/或细胞内信使如 Ca2+?是环状AMP 激活的 GEF (Epac) 参与激活 Rap1？ 3) RabSD 的下游效应蛋白是什么， Rab27B 和 Rap1？是否涉及 Sip 或 Slac 家族的连接蛋白？有没有具体的关系小G蛋白到肌球蛋白Vc？到Noc2？哪些小G蛋白直接或间接调节SNARE 复合体？这项工作将有助于更好地从分子角度理解消化酶的调节腺泡细胞的分泌和实验中发生的病理调节的潜在位点胰腺炎。与公共卫生的相关性：胰腺是分泌消化液的主要器官食物的分解和营养物质的吸收。如果这些酶不可导致炎症性疾病胰腺炎。目前的工作是针对了解参与正常消化酶分泌的蛋白质。