Molecular Mechanisms of Ankyrin-B-based Arrhythmia

基于锚蛋白 B 的心律失常的分子机制

• 批准号: 7079699
• 负责人: Peter J. Mohler
• 金额: $ 33.19万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7079699
• 关键词: Lentivirus; ankyrins; cardiac myocytes; cell type; cytoskeleton; gene expression; gene mutation; heart; laboratory mouse; laboratory rat; long QT syndrome; membrane activity; membrane channels; membrane structure; molecular chaperones; molecular pathology; protein isoforms; protein localization; protein structure function; sudden cardiac death; transport proteins

DESCRIPTION (provided by applicant): Defects in cardiac excitability are the basis for human arrhythmia and sudden cardiac death, a leading cause of mortality in developed countries. Recent findings demonstrate a new paradigm for human arrhythmia based on gene mutations that affect the expression/subcellular localization of cardiac ion channels and transporters. Human type 4 long QT syndrome (LQT4) results from loss-of-function mutations in the membrane adapter ankyrin-B (AnkB). Subjects with LQT4, and mice with reduced AnkB expression display similar complex cardiac phenotypes including atrial, ventricular, conduction defects, and risk of sudden cardiac death. However, the molecular identities of AnkB polypeptides, scope of AnkB expression in specialized cardiac cells, and cellular role(s) for AnkB polypeptides for cardiac excitability remain critical, yet unanswered questions. Moreover, the mechanisms underlying AnkB regulation in normal heart, and dysfunction in human arrhythmia remain unsolved. The long-term objective of this research proposal is to understand the molecular basis for AnkB function in the heart. We hypothesize that coordinate dysfunction of AnkB polypeptides throughout the heart create the complex phenotype of human type 4 long QT syndrome due to defects in ion channel/transporter trafficking and membrane stability. The specific aims are to: 1) Characterize the expression and subcellular distribution of AnkB isoforms in diverse excitable cell types of heart. 2) Define the cellular role(s) of AnkB for ion channel/transporter trafficking and localization in adult cardiomyocytes using recently developed lentiviral techniques. 3) Characterize the mechanisms underlying AnkB regulation in heart, and determine how human AnkB loss-of-function mutations associated with fatal arrhythmia affect this regulation. The cellular pathways underlying ion channel and transporter targeting, localization, and stability in cardiomyocytes are essentially unknown but present an exciting new target for future cardiac therapies. We propose to use recently developed expression techniques to elucidate the molecular mechanisms underlying AnkB-dependent cellular pathways for ion channel and transporter targeting, localization, and stability in the physiological context of the primary cardiomyocyte. It is anticipated that this information will advance understanding of mechanisms underlying AnkB-based human fatal human arrhythmia as well as acquired cardiac arrhythmias associated with abnormal Ca2+ homeostasis, and begin to define potential future molecular targets for the regulation of cellular excitability.

描述（由申请人提供）：心脏兴奋性缺陷是人类心律失常和心源性猝死的基础，而心源性猝死是发达国家死亡的主要原因。最近的研究结果证明了基于影响心脏离子通道和转运蛋白的表达/亚细胞定位的基因突变的人类心律失常的新范例。人类 4 型长 QT 综合征 (LQT4) 是由膜接头锚蛋白 B (AnkB) 的功能丧失突变引起的。具有 LQT4 的受试者和 AnkB 表达减少的小鼠表现出相似的复杂心脏表型，包括心房、心室、传导缺陷和心源性猝死的风险。然而，AnkB 多肽的分子特性、AnkB 在特化心脏细胞中的表达范围以及 AnkB 多肽对心脏兴奋性的细胞作用仍然至关重要，但尚未得到解答。此外，正常心脏中 AnkB 调节和人类心律失常功能障碍的潜在机制仍未解决。本研究计划的长期目标是了解心脏 AnkB 功能的分子基础。我们假设，由于离子通道/转运蛋白运输和膜稳定性的缺陷，整个心脏 AnkB 多肽的协调功能障碍造成了人类 4 型长 QT 综合征的复杂表型。具体目标是： 1) 表征 AnkB 同工型在心脏不同可兴奋细胞类型中的表达和亚细胞分布。 2) 使用最近开发的慢病毒技术定义 AnkB 在成人心肌细胞中离子通道/转运蛋白运输和定位中的细胞作用。 3) 描述心脏中 AnkB 调节的机制，并确定与致命性心律失常相关的人类 AnkB 功能丧失突变如何影响这种调节。心肌细胞中离子通道和转运蛋白靶向、定位和稳定性的细胞途径本质上是未知的，但为未来的心脏治疗提供了令人兴奋的新靶点。我们建议使用最近开发的表达技术来阐明原代心肌细胞生理环境中离子通​​道和转运蛋白靶向、定位和稳定性的 AnkB 依赖性细胞途径的分子机制。预计这些信息将促进对基于 AnkB 的人类致死性心律失常以及与异常 Ca2+ 稳态相关的获得性心律失常的机制的理解，并开始定义未来潜在的细胞兴奋性调节分子靶点。