Calcium regulation of secretion in neuroendocrine cells

神经内分泌细胞分泌的钙调节

• 批准号: 6855754
• 负责人: THOMAS F. J. MARTIN
• 金额: $ 30.58万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-06-10 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6855754
• 关键词: Caenorhabditis elegans; PC12 cells; X ray crystallography; calcium binding protein; calcium ion; cell membrane; crystallization; electrical measurement; electrophysiology; exocytosis; intermolecular interaction; membrane fusion; molecular cloning; molecular site; nerve /myelin protein; neural transmission; neuroendocrine system; neurogenetics; neuroregulation; phosphatidylinositols; phosphorylation; protein structure function; secretion; site directed mutagenesis; syntaxin; yeast two hybrid system

DESCRIPTION (provided by applicant): Synaptic transmission is mediated by release of fast-acting transmitters at synapses via synaptic vesicle (SV) exocytosis. Synaptic modulation is, in contrast, mediated by release from dense-core vesicles (DCVs) of modulatory transmitters that act pre- and postsynaptically to modify synaptic transmission. The understanding of the molecular mechanisms that underlie rapid Ca2+-dependent SV exocytosis has increased over the past decade and the same molecular constituents are required for DCV exocytosis. However, differences in the physiological regulation of SV and DCV exocytosis suggest that there are also molecular mechanisms distinct to each. We discovered that CAPS (ca2+-dependent activator protein for secretion) resides on DCVs but not SVs and is required for DCV but not SV exocytosis. In our continuation studies, we will determine the molecular mechanism through which CAPS acts to facilitate Ca2-dependent DCV fusion with the plasma membrane. This will be accomplished by identifying domains on CAPS that mediate its interactions with plasma and DCV membranes (Aim 1). These studies will define the basis of the DCV-selectivity of CAPS function. To further elucidate the mechanism of CAPS action, the functional importance of its interactions with proteins such as syntaxin, rabphilin and Muncl8 will be determined (Aim 2). These studies will provide a molecular explanation of how CAPS regulates the fusion machinery to facilitate DCV exocytosis. To further define domains of CAPS required for function, we will characterize loss-of-function CAPS mutants as well as determine CAPS structure by X-ray crystallographic studies (Aim 3). To relate the molecular interactions of CAPS to its role in DCV exocytosis, we will study fusion pore dynamics in cells with modified CAPS function (Aim 4). Completion of these studies will provide insight on the regulation of the fusion machinery and on molecular differences between DCV and SV exocytosis. The results may find application in the therapy of nervous system and endocrine disorders that involve hypo- or hypersecretion of monoamine transmitters or peptide hormones.

描述（由申请人提供）：突触传输介导 通过突触囊泡（SV）在突触处释放快速作用发射器 胞吞作用。相反，突触调制是通过从 调节发射器的致密核囊泡（DCV） 突触后修改突触传播。对 基于快速Ca2+依赖性SV胞吐作用的分子机制具有 在过去的十年中增加，需要相同的分子成分 DCV胞吐作用。但是，SV的生理调节差异 DCV胞吐作用表明，也存在与众不同的分子机制 每个。我们发现帽子（Ca2+依赖性激活蛋白用于分泌）） 驻留在DCV上，但不存在于SVS上，而DCV则需要SV胞吐作用。在 我们的继续研究，我们将通过 哪个帽子起作用可促进Ca2依赖性DCV融合与等离子体 膜。这将通过确定介导的帽子上的域来实现 它与血浆和DCV膜的相互作用（AIM 1）。这些研究会 定义CAPS功能的DCV选择性的基础。进一步阐明 CAPS动作的机制，其相互作用的功能重要性 将确定诸如语法素，rabphilin和muncl8之类的蛋白质（目标） 2）。这些研究将提供分子解释帽如何调节 融合机械促进DCV胞吐作用。进一步定义 功能所需的帽子，我们将表征功能丧失的帽突变体 以及通过X射线晶体学研究确定盖结构（AIM 3）。 为了将CAPS的分子相互作用与其在DCV胞吐作用中的作用相关联，我们 将研究具有修饰帽功能的细胞中的融合孔动力学（AIM 4）。 这些研究的完成将提供有关调节的见解 融合机制以及DCV和SV胞吐作用之间的分子差异。 结果可能会在神经系统和内分泌的治疗中找到应用 涉及单胺发射器或过度分泌过度分泌的疾病或 肽激素。