Molecular Basis of Cardiac Arrhythmia and Sudden Death

描述(申请人提供)：心律失常是猝死的主要原因，特别是对于心力衰竭的患者。令人失望的是，目前的大多数治疗方法对生存的好处很少或没有，迫切需要新的治疗方法。心肌钙释放通道(Ryanodine Receptor 2，RyR2)正迅速成为心律失常发病机制中的一个重要环节。RyR2基因突变至少与两种类型的心律失常有关，即儿茶酚胺能多形性室性心动过速(CPVT)和致心律失常的右室心肌病2型(ARVD2)。RyR2通道功能缺陷也与药物引起的心律失常有关。我们的目标是明确致病的RyR2突变和RyR2相互作用的促和抗心律失常药物的作用，以及介导它们作用的通道功能的分子机制，从而为开发有效的抗心律失常治疗提供必要的知识基础。提出了三个具体目标。1.确定CPVT RyR2突变的功能后果。CPVT突变对RyR2通道功能的影响将在全细胞、分子和单通道水平进行研究。2.了解RyR2相互作用的促心律失常药物和抗心律失常药物的分子作用。RyR2相互作用的促心律失常药物和抗心律失常药物对RyR2通道功能的影响将通过单细胞钙成像、单通道分析和放射配基结合等技术组合来评估。3.明确RyR2通道钙调节的分子基础。我们将利用定点突变结合单通道分析来系统地确定通道孔区在RyR2通道钙激活中的作用。这些研究将对RyR2相关性心律失常和猝死的病因机制提供新的和重要的见解，并将对包括心力衰竭在内的各种心脏疾病引起的心律失常的治疗具有深远的意义。

DESCRIPTION (provided by applicant): Cardiac arrhythmia is the leading cause of sudden death, particularly, for patients with heart failure. Disappointingly, most current treatments have little or no survival benefits and new therapies are urgently needed. The cardiac calcium release channel (ryanodine receptor type 2, RyR2) is quickly emerging as an important point in the pathogenesis of cardiac arrhythmia. Mutations in RyR2 have been linked to at least 2 forms of cardiac arrhythmias, catecholaminergic polymorphic ventricular tachycardia (CPVT) and arrhythmogenic right ventricular cardiomyopathy type 2 (ARVD2). Defective RyR2 channel function has also been implicated in drug-induced cardiac arrhythmia. Our goal is to define the actions of disease-causing RyR2 mutations and of RyR2-interacting pro- and anti-arrhythmic agents, and the molecular mechanism of channel function that mediates their actions, thereby providing the knowledge basis necessary for the development of effective anti-arrhythmic therapies. 3 specific aims are proposed. 1. Define the functional consequences of CPVT RyR2 mutations. The functional impacts of CPVT mutations on RyR2 channel function will be investigated at the whole cell, molecular and single channel levels. 2. Understand the molecular actions of RyR2-interacting pro- and anti-arrhythmic agents. The impacts of RyR2-interacting pro- and anti-arrhythmic agents on RyR2 channel function will be assessed by a combination of techniques including single cell calcium imaging, single channel analysis and radioligand binding. 3. Define the molecular basis of calcium regulation of the RyR2 channel. Site-directed mutagenesis in conjunction with single channel analysis will be employed to systematically define the role of the channel pore region in calcium activation of the RyR2 channel. These studies will shed novel and important insight into the causal mechanisms of RyR2-associated cardiac arrhythmias and sudden death, and will have profound implications to the treatment of cardiac arrhythmias arising from various cardiac diseases including heart failure.