Calsequestrin in Ventricular Arrhythmia and Sudden Death

Calsequestrin 治疗室性心律失常和猝死

• 批准号: 8245329
• 负责人: Bjorn C Knollmann
• 金额: $ 39万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-15 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8245329
• 关键词: Adult; Animal Model; Arrhythmia; Binding; Binding Proteins; Biochemical; Calsequestrin; Cardiac; Catecholamines; Cells; Cessation of life; Coronary; Data; Defect; Disease; Electron Microscopy; Exercise; Exhibits; Functional disorder; Funding; Heart; Heart Diseases; Human; Infusion procedures; Inherited; Injury; Knockout Mice; Ligation; Link; Mouse Protein; Mus; Muscle Cells; Mutation; Myocardial Infarction; Myocardial Ischemia; Myocardium; Patients; Phenotype; Predisposition; Proteins; Publishing; Purkinje Cells; Role; RyR2; Sarcoplasmic Reticulum; Sudden Death; Syndrome; System; Tamoxifen; Testing; Tissues; Ventricular; Ventricular Arrhythmia; Ventricular Tachycardia; Wild Type Mouse; Work; gene therapy; high risk; in vivo; mouse junctate protein; mouse model; mutant mouse model; novel; novel strategies; premature; prevent; research study; restoration; sudden cardiac death; trafficking; triadin

DESCRIPTION (provided by applicant): Cardiac calsequestrin (CASQ2), and its binding partners junction and triadin-1 (TRDN), are key regulators of sarcoplasmic reticulum (SR) Ca storage and release. In humans, CASQ2 mutations cause the syndrome of catecholaminergic polymorphic ventricular tachycardia (CPVT) and sudden cardiac death. During the previous funding period, we have generated and studied Casq2 null (Casq2-/-) mice to determine the mechanisms whereby CASQ2 mutations cause electrophysiological instability. We found that despite a lack of Casq2 protein, these mice maintain near normal SR Ca storage, Ca release and contractile function, likely as a result of an expansion of SR volume and drastic reductions in the Casq2 binding proteins triadin-1 and junctin. Casq2-/- mice exhibit the CPVT phenotype, i.e. they develop polymorphic ventricular tachycardia with catecholamine infusion or exercise. Our current concept is that the loss of Ca release refractoriness and premature SR Ca release under conditions of high SR Ca load, results in delayed after-depolarizations, triggered beats and polymorphic ventricular tachycardia. However, if the trigger originates from ventricular myocytes or from specialized cells of the conduction system, the Purkinje cells, is unresolved. Experimental data from a RyR2 mutant mouse model and theoretical considerations favor the Purkinje network. Furthermore, biochemical, electron microscopy and confocal studies show that Casq2 is only found in the terminal cisternae of the junctional SR in close contact with RyR2 Ca release channels. Thus, we hypothesize that the reduced presence of Casq2 near the RyR2 in ventricular myocytes and/or Purkinje cells is a fundamental defect that causes premature SR Ca release and increases arrhythmia susceptibility. This is applicable to inherited syndromes (e.g., Casq2-linked CPVT; Aims 1+2) and potentially acquired heart disease due to defects in the trafficking to and/or retention of Casq2 near the RyR2 (Aim 3). Aim 1: To test the hypothesis that restoration of Casq2 rescues the CPVT phenotype of Casq2-/- mice. Aim 2: To test the hypothesis that loss of Casq2 in Purkinje cells is both necessary and sufficient to cause CPVT Aim 3: To test the hypothesis that Casq2 is reduced near RyR2 Ca release channels in cardiac muscle surviving after myocardial infarction. PUBLIC HEALTH RELEVANCE: The proposed work will study the causes for certain inherited heart diseases associated with arrhythmia (irregular heartbeats) and a high risk for sudden and premature deaths. The studies will also examine the benefit of gene therapy in an animal model, which will provide important information for new therapies for patients with inherited arrhythmia disorders.

描述（由申请人提供）：心脏CALSequestrin（CASQ2）及其结合伙伴交界处和Triadin-1（TRDN）是肌浆网（SR）CA存储和释放的关键调节剂。在人类中，CASQ2突变引起儿茶酚胺能多态性心脏心动过速（CPVT）和心脏猝死的综合征。在上一个资金期间，我们已经生成并研究了CASQ2 NULL（CASQ2 - / - ）小鼠，以确定CASQ2突变导致电生理不稳定的机制。我们发现，尽管缺乏CASQ2蛋白质，但这些小鼠仍将SR CA储存，Ca释放和收缩功能保持在正常的SR CA储存量接近，这可能是由于SR体积的扩展以及Casq2结合蛋白Triadin-1和Junctin的急剧减少而导致的。 CASQ2 - / - 小鼠表现出CPVT表型，即，它们具有及早的儿茶酚胺输注或运动形成多态性心室心动过速。我们目前的概念是，在高SR CA负载条件下，CA释放折射率和过早的SR CA释放释放，导致pe骨后延迟，触发节拍和多态性心室心动过速。但是，如果触发源于室心肌细胞或传导系统的专用细胞，则尚未解决。 RYR2突变小鼠模型和理论考虑的实验数据有利于Purkinje网络。此外，生化，电子显微镜和共共聚焦研究表明，CASQ2仅在连接SR的末端水箱中与RYR2 CA释放通道密切接触。因此，我们假设心室心肌细胞和/或Purkinje细胞在RYR2附近的CASQ2的存在减少是一种基本缺陷，它会导致过早的SR CA释放并增加心律不齐的敏感性。这适用于遗传综合征（例如，CASQ2连接的CPVT； AIMS 1+2）和由于贩运和/或在RYR2附近的Casq2的缺陷而可能获得的心脏病（AIM 3）。目的1：测试CASQ2恢复的假设挽救了CASQ2 - / - 小鼠的CPVT表型。目的2：测试假说，即浦肯野细胞中CASQ2的丢失既需要且足以引起CPVT AIM 3：要测试在心肌梗死后幸存的心脏肌肉中RYR2 CA释放通道附近降低CASQ2的假设。 公共卫生相关性：拟议的工作将研究与心律不齐相关的某些遗传性心脏病（不规则心跳）和突然过早死亡的高风险。这些研究还将检查基因疗法在动物模型中的好处，该模型将为遗传心律失常疾病患者的新疗法提供重要信息。