Distinct Ion Channel Pools and Intercalated Disk Nanoscale Structure Regulate Cardiac Conduction

项目摘要 负责维持心脏兴奋性和传导的关键产电蛋白，包括 钠通道（NaV1.5）、内向整流钾通道（Kir2.1）、L型钙通道 钠-钾ATP酶（NKA）和钠-钙交换剂（NCX）已被广泛应用。 被鉴定为存在于不同的离子通道“池”中，定位于细胞-细胞连接处， 闰盘（ID）。这些不同的离子通道池表明通过“全局”和“局部”调节 控制机制。在ID内，异质纳米级结构导致通道 集中在间隙连接和机械连接周围，形成专门的纳米畴。 ID纳米畴扰动可以诱导质子传导缺陷，并且这些缺陷的破坏可以导致电子传导缺陷。 已经在人类心律失常患者中发现了纳米结构域，这表明这些位点是关键， 传导的决定因素。然而，ID纳米结构和分子组织及其 功能性电生理学的意义还有待于在健康或 疾病 在这个项目中，我们将进行有史以来第一次全面和粒度的ID结构量化 和分子组织使用尖端的光学和电子显微镜技术， 计算分析此外，我们将开发一个新的计算建模框架， 结合这些不同离子通道池（侧膜和ID）的实验测量 和ID纳米级结构，以评估组织尺度心脏传导的调节， 与小鼠心肌光学标测的比较。模拟将预测扩展到 传导，并预测慢性和急性ID扰动如何影响 传导结合其他功能缺陷，包括非缺血性心力衰竭。 在成功完成这些目标后，我们将产生一个新的理论基础， 不同的离子通道池和插盘纳米级结构赋予了“全局/局部控制”， 心脏传导，并提出新的治疗方法，以保持疾病期间的传导 进展

PROJECT SUMMARY Critical electrogenic proteins responsible for maintaining cardiac excitability and conduction, including sodium channels (NaV1.5), inward-rectifying potassium channels (Kir2.1), L-type calcium channels (Cav1.2), sodium-potassium ATPase (NKA), and sodium-calcium exchanger (NCX) have been identified to reside in distinct ion channel ‘pools,’ with localization at the cell-cell junction, the intercalated disk (ID). These distinct ion channel pools suggest regulation via both ‘global’ and ‘local’ control mechanisms. Within the ID, heterogeneous nanoscale structure results in channels concentrating around gap junctions and mechanical junctions, forming specialized nanodomains. ID nanodomains perturbation can induce proarrhythmic conduction defects, and disruption of these nanodomains has been identified in human arrhythmia patients, suggesting that these sites are key determinants of conduction. However, ID nanoscale structure and molecular organization and their implications for functional electrophysiology have yet to be systematically investigated in health or disease. In this project, we will undertake the first-ever comprehensive and granular quantification of ID structure and molecular organization using cutting-edge light and electron microscopy techniques and computational analysis. Further, we will develop a novel computational modeling framework to incorporate experimental measurements of these distinct ion channel pools (lateral membrane and ID) and ID nanoscale structure to assess regulation of tissue-scale cardiac conduction, for direct comparison with optical mapping of murine myocardium. Simulations will extend predictions to conduction in human ventricles and predict how both chronic and acute ID perturbations impact conduction in conjunction with additional functional defects, including non-ischemic heart failure. Upon successful completion of these aims, we will produce a new theoretical underpinning for which distinct ion channel pools and intercalated disk nanoscale structure confer a ‘global/local control’ of cardiac conduction and suggest new therapeutic approaches to preserve conduction during disease progression.