MECHANISMS OF PEPSINOGEN SECRETION FROM CHIEF CELLS

主细胞分泌胃蛋白酶原的机制

• 批准号: 3232530
• 负责人: JEAN-PIERRE RAUFMAN
• 金额: $ 16万
• 依托单位: SUNY DOWNSTATE MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-07-01 至 1991-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3232530
• 关键词: adenylate cyclase; calcium; calcium metabolism; calmodulin; carbachol; cholecystokinin; cholera toxin; cyclic AMP; enzyme induction /repression; guinea pigs; hormone regulation /control mechanism; ionophores; pepsinogens; phosphatidylinositols; phosphorylation; prostaglandins; protein kinase C; radioimmunoassay; secretin; secretion; stomach; vasoactive intestinal peptide

The long-range goals of this project are to elucidate the cellular mechanisms of pepsinogen secretion. For this purpose, the Principal Investigator has developed methods for preparing a nearly homogeneous population of dispersed chief cells that secrete pepsinogen in response to various stimuli. These cells have been used to determine that changes in cAMP mediate the actions of secretin, vasoactive intestinal peptide, prostaglandins, and cholera toxin, whereas changes in cell calcium concentration play a role in mediating the actions of carbachol, cholecystokinin, and calcium ionophores. Although it has been known for several years that potentiation of pepsinogen secretion occurs when agents whose actions involve changes in cAMP are combined with agents whose actions involve changes in cell calcium, the cellular mechanisms mediating this phenomonon were unknown. However, during the previous period of funding, the Principal Investigator discovered that agents whose actions are mediated by changes in cell calcium can potentiate cAMP-mediated enzyme secretion by means of a calcium/calmodulin-dependent activation of the adenylate cyclase system. In other tissues, similar effects appear to be caused by a protein kinase C-mediated phosphorylation of components of adenylate cyclase. Therefore, in the present application, we propose to test the following hypothesis: In chief cells, protein kinase C, activated by secretagogue-induced stimulation of the calcium/phosphoinositide messenger system, has calcium-calmodulin- dependent actions on the adenylate cyclase system that result in augmentation of cellular levels of cAMP, thereby causing potentiation of pepsinogen secretion. This hypothesis will be tested by using various inhibitors of calmodulin and activators and inhibitors of protein kinase C, and by modulating intra- and extra- cellular calcium concentration to determine the role of these cellular mediators in the interaction between second messenger systems. We will also determine whether phosphorylation of chief cell proteins, such as components of the adenylate cyclase system, occurs when cells are stimulated by secretagogues that activate protein kinase C. This new direction for our laboratory will require consultation with faculty in the Dept. of Biochemistry who agree to lend their support to this project. These experiments will increase our understanding of so-called "cross-talk" between second messenger systems in chief cells. Moreover, the new information gained from these studies should increase our understanding of signal transduction in secretory cells in general.

该项目的长期目标是阐明细胞 胃蛋白酶原分泌机制。 为此， 首席研究员开发了一种方法来准备近乎 分散的主细胞同质群体，分泌 胃蛋白酶原对各种刺激作出反应。 这些细胞已 用于确定 cAMP 的变化介导的作用 促胰液素、血管活性肠肽、前列腺素和 霍乱毒素，而细胞钙浓度的变化则发挥作用 介导卡巴胆碱、胆囊收缩素和 钙离子载体。 虽然已经知道好几年了 当以下药物作用时，胃蛋白酶原分泌会增强： 涉及 cAMP 变化的行动与以下药物组合： 作用涉及细胞钙的变化，细胞机制 介导这种现象的因素尚不清楚。 然而，在此期间 首席研究员发现，上一期的资助 其作用是由细胞钙的变化介导的药物 可以通过以下方式增强 cAMP 介导的酶分泌 腺苷酸环化酶的钙/钙调蛋白依赖性激活 系统。 在其他组织中，类似的效果似乎是由 蛋白激酶 C 介导的组分磷酸化 腺苷酸环化酶。 因此，在本申请中，我们 提议检验以下假设：在主细胞中，蛋白质 激酶 C，由促分泌素诱导的刺激激活 钙/磷酸肌醇信使系统，具有钙-钙调蛋白- 依赖于腺苷酸环化酶系统的作用，导致 增加细胞内 cAMP 水平，从而导致 胃蛋白酶原分泌增强。 这个假设将是 通过使用各种钙调蛋白抑制剂和激活剂进行测试， 蛋白激酶 C 抑制剂，并通过调节内和外 细胞钙浓度确定这些的作用 第二信使之间相互作用的细胞介质 系统。 我们还将确定主要的磷酸化是否 细胞蛋白，例如腺苷酸环化酶系统的成分， 当细胞受到促分泌素刺激时发生 蛋白激酶 C。我们实验室的这个新方向将 需要咨询生物化学系的教员 同意为该项目提供支持。 这些实验 将增加我们对之间所谓的“串扰”的理解 主细胞中的第二信使系统。 此外，新 从这些研究中获得的信息应该会增加我们的 一般性地了解分泌细胞中的信号转导。