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: 8203098
• 负责人: Courtney Michelle Campbell
• 金额: $ 2.64万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8203098
• 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. PUBLIC HEALTH RELEVANCE: The mechanism for atrial fibrillation (AF), the most common cardiac arrhythmia in adults, is poorly understood, and a better grasp of its molecular basis may lead to improved therapies and prevention. Because AF does not present during childhood, the combination of both genetic predisposition with factors acquired during life may underlie this disorder. These proposed studies will investigate the interaction between a causative AF mutation and oxidative stress, an established AF risk factor that increases with advancing age.

描述（由申请人提供）：房颤（AF）是成年人中最常见的心律失常，影响了200万以上的美国人，但其分子病因学很少了解。在种群和隔离特定突变的家族中已经证明了对AF的遗传易感性。这些突变预计会在细胞水平上赋予对AF的敏感性。但是，在童年期间不存在家族性AF，表明仅遗传易感性就不足以引起该疾病。因此，假定生命中获得的其他因素与遗传确定的细胞底物相互作用，以使临床表型的全部表达。在确定AF易感性中的组合遗传和获得因素的累加或协同作用尚未在机械水平上探索。拟议的研究将研究与家族性AF相关的KCNQ1（S140G）中缓慢延迟整流器电流（IKS）功能增益突变的细胞后果，并探讨如何通过氧化应激（一种常见且良好的氧化应激）改变遗传风险。公认的获得因子在AF的发病机理中。在特定的目标1中，将用重组病毒转导兔心肌细胞，以表达野生型（WT）或突变通道。使用全细胞电生理记录，这些研究将测试在体外观​​察到的KCNQ1-S140G的功能获得特征是否转化为升高到电流密度升高和房间肌细胞中的APD缩短。在特定的目标2中，电生理研究将在急性和延长的氧化应激暴露下表征异源表达的WT或突变通道，并通过施用过氧化氢的氧化氧化应激暴露。这些结果将揭示氧化应激暴露发生的通道中功能变化的类型。在特定的目标3中，实验将检验以下假设：心房心肌细胞中的氧化应激以一种增强突变通道表达赋予的AF敏感性的方式改变电生理学。心肌细胞将在电生理记录期间急性抗氧化应激或培养时间长时间。将分析记录的APD和动作潜力扰动，例如在不同的起搏频率期间去极化后的早期或延迟。这些实验将促进我们对遗传因素和获得的病理生理状况如何相互作用以在细胞水平产生AF敏感性的理解，并可能导致更好的疗法和预防。 公共卫生相关性：房颤的机制（AF）是成年人中最常见的心律不齐的最常见的心律失常，对其分子基础的更好掌握可能会导致改善的疗法和预防。由于AF在童年时期不存在，因此两种遗传易感性与生命中获得的因素的结合可能是这种疾病的基础。这些提出的研究将研究因果AF突变与氧化应激之间的相互作用，这是随着年龄增长而增加的已建立的AF风险因素。