Molecular Physiology of TRPC Channels

TRPC 通道的分子生理学

• 批准号: 7303055
• 负责人: Alexander G. Obukhov
• 金额: $ 34.01万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-04 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7303055
• 关键词: calcium flux; catecholamines; chromaffin cells; corticosterone; dexamethasone; exocytosis; growth factor; hormone regulation /control mechanism; immunocytochemistry; laboratory rat; membrane channels; membrane permeability; molecular biology; protein localization; receptor expression; secretion; stoichiometry; tissue /cell culture; voltage /patch clamp

DESCRIPTION (provided by applicant): The long-term objective of this research proposal is to understand the molecular mechanisms involved in controlling hormone-induced Ca2+ influx. Receptor-operated and store-operated cation channels (ROC and SOC) represent vital Ca2+ influx pathways in almost all cellular systems. ROC and SOC play a crucial role in mediating numerous cellular functions including exocytosis and contraction. In adrenal chromaffin cells (ACC), circulating-hormone-activated ROC and SOC channels act in concert with voltage-gated Ca2+ channels to modulate exocytosis of catecholamines, essential regulators of vascular tone, cardiac output and heart rate. Little is known about the molecular nature of hormone-activated ROC and SOC in ACC. A growing body of evidence suggests that Canonical Transient Receptor Potential (TRPC) channels can form, or be a component of, ROC and SOC in various cell types. We have shown that TRPC channels are expressed in ACC and that over-expression of TRPCs increases sustained Ca influx and catecholamine secretion. A factor that determines Ca2+ influx through TRPCs is channel permeability. Regulation of TRPC channel permeability is not well understood, however, certain heteromers of TRPC channels exhibit reduced permeability. We hypothesize that TRPCs mediate hormone-evoked exocytosis in ACC and their heteromerization serves to regulate this ability. This project is aimed to identify the role and the regulation of endogenous TRPC channels in ACC. To do this we will use molecular biological, biochemical, patch-clamp and fluorescence imaging methods to address the following specific aims: (1) identify which TRPCs are endogenously expressed in ACC; (2) identify mechanisms regulating the expression of endogenous TRPCs in ACC; and (3) identify the molecular determinants governing heteromeric TRPC permeability. Together these studies will shed light on the mechanisms regulating circulating-hormone-activated catecholamine exocytosis in ACC. Catecholamines are crucial regulators of the cardiovascular function, therefore, understanding mechanisms involved in controlling secretion of catecholamines in ACC is an important health care issue.

描述（由申请人提供）：本研究计划的长期目标是了解控制激素诱导的 Ca2+ 流入的分子机制。受体操纵和存储操纵的阳离子通道（ROC 和 SOC）代表几乎所有细胞系统中重要的 Ca2+ 流入途径。 ROC 和 SOC 在介导许多细胞功能（包括胞吐作用和收缩）中发挥着至关重要的作用。在肾上腺嗜铬细胞 (ACC) 中，循环激素激活的 ROC 和 SOC 通道与电压门控 Ca2+ 通道协同作用，调节儿茶酚胺的胞吐作用，儿茶酚胺是血管张力、心输出量和心率的重要调节剂。对于 ACC 中激素激活的 ROC 和 SOC 的分子性质知之甚少。越来越多的证据表明，规范瞬时受体电位 (TRPC) 通道可以在各种细胞类型中形成 ROC 和 SOC，或者成为 ROC 和 SOC 的组成部分。我们已经证明 TRPC 通道在 ACC 中表达，并且 TRPC 的过度表达会增加持续的 Ca 流入和儿茶酚胺分泌。决定 Ca2+ 通过 TRPC 流入的一个因素是通道渗透性。 TRPC 通道通透性的调节尚不清楚，然而，TRPC 通道的某些异聚体表现出通透性降低。我们假设 TRPC 介导 ACC 中激素诱发的胞吐作用，并且它们的异聚化有助于调节这种能力。该项目旨在确定 ACC 中内源性 TRPC 通道的作用和调节。为此，我们将使用分子生物学、生化、膜片钳和荧光成像方法来实现以下具体目标：（1）确定哪些TRPC在ACC中内源表达； (2) 确定调节 ACC 中内源性 TRPC 表达的机制； (3) 确定控制异聚 TRPC 渗透性的分子决定因素。这些研究将共同​​揭示 ACC 中循环激素激活的儿茶酚胺胞吐作用的调节机制。儿茶酚胺是心血管功能的重要调节剂，因此，了解控制 ACC 中儿茶酚胺分泌的机制是一个重要的卫生保健问题。