Ion channels and sudden cardiac death

本申请中提出的研究的总体目标是确定引发致命性心律失常的细胞和分子触发因素，并确定新的基因靶向治疗策略来治疗它们。我们的中心假设是，该过程中的一个步骤是由疾病相关突变引起的表面膜离子通道蛋白和/或关键信号分子（与项目1合作）的生物物理和调节特性的改变引起的膜电活性的扰动。通道活动的这种变化可以改变配置，并且进而触发器。改变的离子通道特性也可以赋予编码的离子通道和/或与长QT综合征（LQTS）和Brudaga综合征（BrS）相关的信号分子独特的药理学特性，作为测试这些假设的范例。这个项目有三个目标。目的1是检验突变型离子通道的生物物理性质存在异质性的假设，这些突变型离子通道与细胞和疾病表型有因果关系。目的2是检验以下假设：疾病相关通道特性的异质性通过信号传导或离子通道分子中的突变（多态性）赋予β-受体/通道偶联，从而以增加糖尿病事件风险的方式破坏通道调节。所提出的实验将联合收割机测量哺乳动物细胞中瞬时表达的重组通道活性。我们的预测的理论测试将使用基于计算机的心脏动作电位模拟，结合我们的膜片钳数据进行。此外，将使用遗传改变动物模型中的全身测量（ECG）来检测离子通道特性变化与心脏中代谢活动发生之间的关系。我们假设从这些细胞和分子实验中获得的信息可以直接转化为改善人类的治疗干预，因此这项工作有可能在分子水平上确定心脏性猝死（SCD）的机制基础，并根据突变基因产物的特定特性开发人类的治疗策略。

The overall goal of the research proposed in this application is to identify the cellular and molecular triggers that initiate fatal cardiac arrhythmias and to determine novel gene-targeted therapeutic strategies to treat them. Our central hypothesis is that one step in this process is perturbation of membrane electrical activity caused by alteration in the biophysical and regulatory properties of surface membrane ion channel proteins and/or in key signaling molecules (in collaboration with Project 1) by diseased- linked mutations. This changes in channel activity may alter the configuration may alter the configuration 4) and, in turn, triggers arrhythmic. Altered ion channel properties may also confer unique pharmacological properties upon the encoded ion channels and/or signaling molecules linked to the long QT syndrome (LQTS) and Brudaga's syndrome (BrS) as paradigms to test these hypotheses. There are three aims of this project. Aim 1 is to test the hypothesis that there is heterogeneity in biophysical properties of mutant ion channels that are causally related to cellular and disease phenotypes. Aim 2 is to test the hypothesis that heterogeneity in disease-linked channel properties confers beta-receptor/channel coupling either by mutations (polymorphisms) in signaling or in ion channel molecules disrupts channel regulation in a manner that increases the risk of an arrhythmic event. Experiments that are proposed will combine patch clamp measurement of recombinant channel activity transiently expressed in mammalian cells. Theoretical testing of our predictions will be carried out using computer-based simulations of cardiac action potentials that incorporate our patch clamp data. In addition, systemic measurements (ECG) in genetically-altered animal models will be used to test the relationship between changes in ion channel properties and the genesis of arrhythmic activity in the heart. We hypothesize that information gained from these cellular and molecular experiments can be translated directly to improved therapeutic intervention in man. Thus this work has the potential to determine a mechanistic basis for Sudden Cardiac Death (SCD) at the molecular level, and to develop therapeutic strategies in man based on specific properties for mutant gene products.