Modulation of Cardiac E-C Coupling by Sorcin

Sorcin 对心脏 E-C 耦合的调节

• 批准号: 7023828
• 负责人: Hector H Valdivia
• 金额: $ 35.28万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7023828
• 关键词: calcium binding protein; calcium channel; genetically modified animals; heart; heart cell; heart electrical activity; laboratory mouse; mutant; myocardium; phosphorylation; protein protein interaction; protein structure; tissue /cell culture; transfection; voltage /patch clamp

DESCRIPTION (provided by applicant): Excitation-contraction (E-C) coupling is a Ca-dependent process in cardiac muscle. Depolarization of the surface membrane permits a small influx of Ca (the inward Ca current, ICa). ICa then evokes Ca release from the sarcoplasmic reticulum (SR), a process termed Ca-induced Ca release (CICR). The protein responsible for CICR is the Ca release channel/ryanodine receptor (RyR). Isolated RyRs are "eager Ca responders" that quickly open when (Ca) rises and remain open as long as (Ca) remains high. This willingness of RyRs to act as Ca indicators is surprising given that in cellular settings RyRs quickly close despite (Ca) being high, thereby avoiding SR Ca depletion and overflowing of cytosolic compartments with Ca. The mechanism(s) that allows RyR closure in vivo is unknown. This proposal will determine whether sorcin, a novel Ca-binding protein inhibitor of RyRs, is an important component of the mechanism that quenches CICR in intact cells. The specific aims are: 1) To establish the structural determinants of sorcin modulation of cardiac RyRs. We will determine the kinetics of sorcin interaction with RyRs and the role played by phosphorylation. Also, we will obtain sorcin mutants that are unable to bind Ca in one or several of its five E-F hands as well as sorcin mutants unable to undergo phosphorylation; of special interest is F112L-sorcin, a sorcin mutant associated with Familial Hypertrophic Cardiomyopathy and hypertension. 2) To determine the role of sorcin in regulation of Ca release and E-C coupling of cardiac cells. We will determine effects of sorcin in localized and global Ca release in intact and permeabilized cardiac myocytes. We will also determine the effects of overexpression and ablated expression of sorcin in ventricular cells. Finally, we will characterize a sorcin-null transgenic mouse.

描述（由申请人提供）：激发 - 收缩（E-C）耦合是心脏肌肉中的CA依赖性过程。 表面膜的去极化允许少量的Ca（内向Ca电流，ICA）涌入。 然后，ICA唤起了CA从肌浆网（SR）中释放，该过程称为CA诱导的Ca释放（CICR）。 负责CICR的蛋白质是Ca释放通道/ryanodine受体（RYR）。 孤立的Ryrs是“急切的CA响应者”，当（CA）上升并保持开放时，只要（CA）保持较高。 瑞尔（Ryrs）充当CA指标的意愿是令人惊讶的，因为在蜂窝设置中，RYRS迅速关闭，尽管（CA）很高，从而避免了SR CA的耗竭并溢出了带有Ca的胞质隔室的溢出。 允许在体内闭合的机制未知。 该建议将确定Sorcin是Ryrs的新型CA结合蛋白抑制剂，是溶解完整细胞中CICR的机制的重要组成部分。 具体目的是：1）建立心脏瑞尔斯山霉素调节的结构决定因素。 我们将确定与Ryrs相互作用的动力学和磷酸化的作用。 同样，我们将获得无法在其五只E-F手中的一个或几个CA以及无法进行磷酸化的sorcin突变体中结合Ca的sorcin突变体。特殊感兴趣的是F112L-氧素，这是一种与家族性心肌病和高血压相关的sorcin突变体。 2）确定sorcin在调节心脏细胞的Ca释放和E-C偶联中的作用。 我们将在完整和透化心肌细胞中确定sorcin在局部和全球CA释放中的影响。 我们还将确定心室细胞中狼蛋白的过表达和消融表达的影响。 最后，我们将表征sorcin-null转基因小鼠。