REGULATION OF ZYMOGEN GRANULE K+ TRANSPORT/EXOCYTOSIS

受调控的胞吐作用是细胞对 通过将储存的产物释放到细胞外来传递生理信号 通过分泌颗粒与血浆的融合而形成的环境 薄膜。胞吐作用是消化、唾液分泌的基础， 肺维持、内分泌释放和突触传递。一个 这一系统的具体故障是导致病理的原因 与囊性纤维化有关。为了理解和纠正 胞吐功能紊乱，必须首先弄清其基本机制。 这项建议使用了具有良好特性的大鼠胰腺作为模型，并且 旨在阐明分泌颗粒电解质之间的耦合 转运和胞吐膜融合。这些分泌颗粒 含有氯离子和钾离子通道，在以下情况下能够进行净盐运移 激活了。具体地说，项目将确定机制 负责激活胰腺中的KATP通道 酶原颗粒及其生理作用 频道。使用分离的酵素原颗粒，KATP通道将被 电生理学检查和G蛋白偶联途径 我们将演示如何激活。被测试的模型提出， 颗粒KATP通道负责控制净颗粒盐 运输和肿胀。使用体外膜融合试验， 这一颗粒通道的激活和净溶质运输将是 被证明有助于胞吐事件的效率或速率。 这些实验将进一步区分颗粒运输 对初始熔融孔的形成有直接贡献 或者通过简单地使微孔进入完整的膜 通过拓宽和稳定连接实现融合。

Regulated exocytosis is the process whereby a cell responds to a physiological signal by releasing a stored product into the extracellular environment through the fusion of secretory granules with the plasma membrane. Exocytosis is fundamental to digestion, salivary secretion, lung maintenance, endocrine release, and synaptic transmission. A specific failure of this system is responsible for the pathology associated with cystic fibrosis. In order to understand and rectify disturbances of exocytosis, the basic mechanism must first be clarified. This proposal uses the well characterized rat pancreas as a model, and is designed to elucidate a coupling between secretory granule electrolyte transport and exocytotic membrane fusion. These secretory granules contain Cl-and K+ channels that are capable of net salt transport when activated. Specifically, the project will determine the mechanism responsible for the activation of the KATP channel in the pancreatic zymogen granule along with the physiological role of these granule ion channels. Using isolated zymogen granules, the KATP channel will be examined electrophysiologically and a G-protein coupled route to activation will be demonstrated. The model to be tested proposes that the granule KATP channel is responsible for controlling net granule salt transport and swelling. Using in vitro assays for membrane fusion, the activation of this granule channel, and net solute transport, will be shown to contribute to the efficiency or rate of the exocytotic event. The experiments will further differentiate between granule transport having a direct contribution to the formation of the initial fusion pore or by simply causing the microscopic pore to proceed to full membrane fusion via the widening and stabilizing of the connection.