Exocrine Pancreatic Zymogen Activation

外分泌胰腺酶原激活

基本信息

批准号：
8099725
负责人：
Fred Sanford Gorelick
金额：
$ 23万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-07-15 至 2013-06-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): The pathologic proteolytic activation of digestive zymogens (primarily proteases such as chymotrypsinogen) within pancreatic acinar cells is a key step in initiating acute pancreatitis. Our laboratory examines extracellular factors and intracellular mechanisms responsible for this activation. Supraphysiologic (>10 fold than required for maximal secretion), but not physiologic concentrations of cholecystokinin (CCK), given in vivo cause zymogen activation and pancreatitis. Similarly treated isolated pancreatic acinar cells respond with zymogen activation and injury. Factors that can sensitize the acinar cell might convert the physiologic actions of CCK and other ligands to pathologic responses and may be relevant to the pathogenesis of acute pancreatitis. For example, experimental studies of pancreatitis induced by ischemia, bile salts, the CDE diet, pancreatic duct obstruction and ethanol suggest that such sensitization contributes to disease. During our past funding period we reported the sensitizing effects of cAMP agonists and alcohols on CCK-induced zymogen activation. We propose to continue examining the mechanisms of sensitization. Further, we have also found that the assembly and activation of a vacuolar ATPase (vATPase) is central to acinar cell zymogen activation. Indeed, it may be the final mediator of the zymogen activation response. It is relevant vATPase's containing distinct isoforms can be localized to specific organelles and activated by different mechanisms. Preliminary studies suggest that zymogen activation takes place in a compartment associated with a specific vATPase isoform (V0a2). Given the importance of the vATPase in this phenomenon and its role in other cell systems, it will be a major focus of our studies. The following specific aims will be pursued. 1) Define the vacuolar ATPase subunit composition, subcellular distribution, localization and assembly responses after cholecystokinin treatment in acini and in vivo using physiologic conditions and those that generate acute pancreatitis, 2) Examine the sensitizing effects alcohols and glucose on pathologic zymogen activation in the pancreatic acinar cell and vATPase activation and assembly, 3) Examine the effects of specific signaling pathways (cAMP, PKC, AMPK) on zymogen activation and vATPase assembly in intact cells and in a cell-free system and the effects of the vATPase on calcium signaling, 4) Develop new approaches to reduce vATPase activity using molecular and biochemical approaches.

描述（由申请人提供）：胰腺腺泡细胞内消化酶原（主要是蛋白酶，如胰凝乳蛋白酶原）的病理性蛋白水解激活是引发急性胰腺炎的关键步骤。我们的实验室检查负责这种激活的细胞外因素和细胞内机制。胆囊收缩素 (CCK) 的超生理浓度（> 最大分泌所需的 10 倍），但不是生理浓度，体内给予会导致酶原激活和胰腺炎。类似处理的分离的胰腺腺泡细胞响应酶原激活和损伤。使腺泡细胞敏感的因素可能将CCK和其他配体的生理作用转化为病理反应，并可能与急性胰腺炎的发病机制有关。例如，对由缺血、胆盐、CDE 饮食、胰管阻塞和乙醇诱发的胰腺炎的实验研究表明，这种致敏作用会导致疾病。在我们过去的资助期间，我们报告了 cAMP 激动剂和酒精对 CCK 诱导的酶原激活的敏化作用。我们建议继续研究敏化机制。此外，我们还发现液泡 ATP 酶（vATP 酶）的组装和激活对于腺泡细胞酶原激活至关重要。事实上，它可能是酶原激活反应的最终介质。相关的 vATP 酶含有不同的亚型，可以定位到特定的细胞器并通过不同的机制激活。初步研究表明，酶原激活发生在与特定 vATP 酶亚型 (V0a2) 相关的隔室中。鉴于 vATP 酶在这一现象中的重要性及其在其他细胞系统中的作用，它将成为我们研究的主要焦点。将追求以下具体目标。 1) 使用生理条件和产生急性胰腺炎的条件，定义在腺泡和体内经胆囊收缩素处理后的液泡 ATP 酶亚基组成、亚细胞分布、定位和组装反应，2) 检查酒精和葡萄糖对胰腺病理性酶原激活的敏化作用腺泡细胞和vATP酶的激活和组装，3）检查特定信号通路（cAMP、PKC、AMPK）对完整细胞和无细胞系统中的酶原激活和 vATPase 组装以及 vATPase 对钙信号传导的影响，4) 使用分子和生化方法开发新方法来降低 vATPase 活性。