Mechanism of Atrial Fibrillation Susceptibility Due to Mutant Potassium Channels

钾通道突变导致心房颤动易感性的机制

• 批准号: 8603275
• 负责人: Courtney Michelle Campbell
• 金额: $ 4.77万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-02-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8603275
• 关键词: Action Potentials; Acute; Adenoviruses; Adult; Affect; American; Arrhythmia; Atrial Fibrillation; Cardiac Myocytes; Cardiology; Cells; Characteristics; Childhood; Coupled; Disease; Doctor of Philosophy; Elderly; Electrophysiology (science); Etiology; Exposure to; Family; Frequencies; Gene Mutation; Genetic; Genetic Predisposition to Disease; Genetic Risk; Goals; Heart Atrium; Hydrogen Peroxide; In Vitro; Lead; Life; Link; Mammalian Cell; Membrane; Molecular; Morphology; Muscle Cells; Mutation; Oryctolagus cuniculus; Oxidative Stress; Pathogenesis; Pharmacology; Physicians; Population; Potassium; Potassium Channel; Predisposition; Prevention therapy; Property; Recombinants; Refractory; Relative (related person); Research; Research Support; Risk; Risk Factors; Scientist; System; Testing; Tissues; Training; Translating; Work; acquired factor; base; clinical phenotype; density; gain of function; gain of function mutation; gene environment interaction; grasp; improved; mutant; pre-doctoral; recombinant virus; research study; theories

DESCRIPTION (provided by applicant): Atrial fibrillation (AF) is the most common cardiac arrhythmia in adults, affecting over 2 million Americans, yet its molecular etiology is poorly understood. Genetic predisposition to AF has been demonstrated in populations and in families segregating specific mutations. These mutations are predicted to confer susceptibility to AF at the cellular level. However, familial AF does not present during childhood suggesting that genetic predisposition alone is not sufficient to cause the disease. Therefore, other factors acquired during life are presumed to interact with the genetically determined cellular substrate for the full expression of the clinical phenotype. The additive or synergistic effects of combined genetic and acquired factors in determining AF susceptibility have not been explored at the mechanistic level. The proposed studies will investigate the cellular consequences of a slow delayed rectifier current (IKs) gain-of-function mutation in KCNQ1 (S140G) linked with familial AF and to explore how the genetic risk is modified by oxidative stress, a common and well- recognized acquired factor in the pathogenesis of AF. In Specific Aim 1, rabbit atrial myocytes will be transduced with recombinant virus to express either wild-type (WT) or mutant channels. Using whole-cell electrophysiological recording, these studies will test whether gain-of-function characteristics of KCNQ1- S140G observed in vitro translate to increased current density and a shortened APD in atrial myocytes. In Specific Aim 2, electrophysiological studies will characterize heterologously expressed WT or mutant channels in mammalian cells under acute and prolonged oxidative stress exposure, mimicked by hydrogen peroxide application. These results will disclose the types of functional changes in the channel that occur with oxidative stress exposure. In Specific Aim 3, experiments will test the hypothesis that oxidative stress in atrial myocytes alters electrophysiology in a manner that potentiates AF-susceptibility conferred by mutant channel expression. Atrial myocytes will be exposed to oxidative stress either acutely during electrophysiological recording or for a prolonged duration in culture. Recordings will be analyzed for APD and action potential perturbations such as early or delayed after depolarizations during different pacing frequencies. These experiments will advance our understanding of how genetic factors and acquired pathophysiological conditions interact to produce AF susceptibility at the cellular level and may lead to better therapies and prevention.

描述（由申请人提供）：心房颤动 (AF) 是成人中最常见的心律失常，影响超过 200 万美国人，但其分子病因学却知之甚少。房颤的遗传易感性已在人群和家族中被证明具有特定突变。预计这些突变会在细胞水平上赋予房颤易感性。然而，家族性房颤在儿童时期并不存在，这表明仅遗传倾向不足以引起该疾病。因此，推测生命期间获得的其他因素与遗传决定的细胞底物相互作用，以实现临床表型的充分表达。尚未在机制水平上探讨遗传因素和后天因素组合在确定 AF 易感性方面的累加或协同效应。拟议的研究将调查与家族性房颤相关的 KCNQ1 (S140G) 中缓慢延迟整流电流 (IK) 功能获得突变的细胞后果，并探讨氧化应激（一种常见且良好的）如何改变遗传风险。公认的 AF 发病机制中的获得性因素。在具体目标 1 中，将用重组病毒转导兔心房肌细胞以表达野生型 (WT) 或突变型通道。这些研究将使用全细胞电生理记录来测试体外观察到的 KCNQ1-S140G 的功能获得特征是否会转化为心房肌细胞中电流密度的增加和 APD 的缩短。在具体目标 2 中，电生理学研究将表征哺乳动物细胞在急性和长期氧化应激暴露（通过过氧化氢应用模拟）下异源表达的 WT 或突变通道。这些结果将揭示因氧化应激暴露而发生的通道功能变化的类型。在具体目标 3 中，实验将检验以下假设：心房肌细胞中的氧化应激会改变电生理学，从而增强突变通道表达所赋予的 AF 易感性。心房肌细胞在电生理记录期间或在培养中长时间暴露于氧化应激中。将分析记录的 APD 和动作电位扰动，例如不同起搏频率期间去极化的提前或延迟。这些实验将加深我们对遗传因素和后天病理生理条件如何相互作用从而在细胞水平上产生房颤易感性的理解，并可能带来更好的治疗和预防。