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）：该研究建议的长期目标是了解控制激素诱导的Ca2+涌入所涉及的分子机制。受体经营和储存的阳离子通道（ROC和SOC）几乎代表了几乎所有细胞系统中的重要CA2+涌入途径。 ROC和SOC在介导许多细胞功能（包括胞吐和收缩）中起着至关重要的作用。在肾上腺染色体细胞（ACC）中，循环激活的ROC和SOC通道与电压门控CA2+通道共同起作用，可调节儿茶酚胺的胞吐作用，血管张力，心脏输出和心脏速率的基本调节剂。关于激素激活的ROC和ACC中SOC的分子性质知之甚少。越来越多的证据表明，规范瞬态受体电位（TRPC）通道可以形成或成为各种细胞类型的ROC和SOC的组成部分。我们已经表明，TRPC通道在ACC中表达，TRPC的过表达增加了CA的涌入和儿茶酚胺分泌。确定通过TRPC的CA2+流入的因素是通道渗透性。 TRPC通道渗透率的调节尚不清楚，但是，TRPC通道的某些异构体表现出降低的渗透性。我们假设TRPC介导ACC中激素诱发的胞吐作用，它们的异质化有助于调节这种能力。该项目的目的是确定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，斑块钳和荧光成像方法来解决以下特定目的：（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）确定控制异源TRPC渗透性的分子决定因素。这些研究共同阐明了调节ACC中循环激素激活的儿茶酚胺胞吐的机制。儿茶酚胺是心血管功能的关键调节剂，因此，了解控制儿茶酚胺在ACC中涉及的机制是一个重要的医疗保健问题。