INTRACELLULAR FGFS:NOVEL REGULATIONS OF CARDIAC NAV CHANNELS

细胞内 FGFS：心脏 NAV 通道的新颖调节

• 批准号: 8206862
• 负责人: JEANNE M. NERBONNE
• 金额: $ 19万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2013-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8206862
• 关键词: Action Potentials; Adult; Affect; Arrhythmia; Atrial Fibrillation; Attenuated; Binding; Biochemical; C-terminal; Cardiac; Cell surface; Cells; Cytoplasmic Granules; Disease; Family; Fibroblast Growth Factor; Future; Gene Targeting; Generations; Goals; Heart; Heart Diseases; In Vitro; Inherited; Investigation; Ion Channel; Life; Link; Longitudinal Studies; Mediating; Membrane; Molecular; Molecular Genetics; Multiprotein Complexes; Mus; Muscle Cells; Mutation; Myocardial; Myocardium; Neonatal; Neurons; Pathway interactions; Physiological; Play; Property; Proteins; RNA Interference; Receptor Protein-Tyrosine Kinases; Regulation; Reporting; Research; Research Proposals; Risk; Role; Sick Sinus Syndrome; Small Interfering RNA; Sodium; Specificity; Syndrome; System; Testing; Ventricular; density; fibroblast growth factor 13; genetic regulatory protein; heart rhythm; hippocampal pyramidal neuron; in vivo; insight; neuronal excitability; novel; novel strategies; programs; protein complex; research study; small hairpin RNA; therapeutic target; trafficking; voltage

Voltage-gated Na+ (Nav) channels are responsible for the rapid upstroke of the action potential in cardiac cells and play critical roles in controling action potential durations and propagation. The primary Nav pore- forming (¿) subunit in the myocardium is Nav1.5, encoded by SCN5A, and mutations in SCN5A have been linked to a number of cardiac rhythm disorders, including Long QT3 syndrome, Brugada syndrome, cardiac conduction disease, sick sinus syndrome, and atrial fibrillation. Accumulating evidence suggests that myocardial Nav channels function in multimeric protein complexes, comprising one Nav¿ subunit, accessory (¿) subunits and a number other accessory/regulatory proteins, although the roles of accessory and regulatory proteins in controling channel expression, properties and subcellular distributions are not well understood. This R21 proposal will test the hypothesis that intracellular fibroblast growth factors (iFGFs) function as novel regulators of myocardial Nav1.5-encoded channels. This hypothesis is motivated by recent preliminary studies demonstrating that iFGF13 is expressed in adult and neonatal (mouse) ventricles and that iFGF13-targeted RNA interference markedly attenuates Nav current densities in (neonatal mouse ventricular) myocytes. There are two related aims in this proposal, and these will be pursued in parallel. Specifically, the studies outlined here will test the hypothesis that iFGF13 selectively regulates ventricular Nav currents and plays a physiological role in the generation of ventricular action potentials (aim #1). Parallel studies will explore the hypothesis that iFGF13 functions to regulate the stability, the trafficking and/or the subcellular localization of Nav1.5-encoded ventricular Nav channels (aim #2). To achieve these aims, the expression of iFGF13 will be manipulated in (mouse) ventricular myocytes in vitro using targeted gene "knockdown" strategies with small interfering RNAs (siRNAs), and the functional consequences of these manipulations on the properties and the cell surface expression of Nav (and other) channels will be determined. Parallel experiments will be completed on myocytes isolated from mice (Fgf13-/-) harboring a targeted disruption of the Fgf13 locus. It is anticipated that the studies proposed here will provide new and fundamentally important insights into the role(s) of the iFGFs in the dynamic regulation of myocardial Nav channels. In addition, the results of these studies will guide future investigations focused on delineating the molecular, cellular and systemic mechanisms involved in the dynamic regulation of myocardial membrane excitability and in the derangements in cardiac excitability linked to mutations in SCN5A. In the long term, it is anticipated that these studies will provide important new insights into the potential of the iFGFs as therapeutic targets to modulate Nav channel functioning in inherited and acquired cardiac rhythm disorders.

电压门控的NA+（NAV）通道负责心脏动作潜力的快速上风 细胞并在控制动作潜在持续时间和传播中起关键作用。主要导航孔 - 心肌中的（由SCN5A编码）形成（�）亚基，SCN5A中的突变已是 链接到许多心律节奏疾病，包括长QT3综合征，Brugada综合征，心脏 传导疾病，病态的鼻窦综合征和心房颤动。积累的证据表明 心肌NAV通道功能在多种体蛋白复合物中的功能，涵盖一个NAV subunit， 附件（）亚基和其他附件/调节蛋白，尽管附件的角色 在控制通道表达，性质和亚细胞分布中，调节蛋白不是很好 理解。该R21提案将检验以下假设：细胞内成纤维细胞生长因子（IFGFS） 充当心肌NAV1.5编码通道的新型调节剂。这个假设是由 最近的初步研究表明，IFGF13在成人和新生儿（小鼠）心室中表达 并且IFGF13靶向的RNA干扰显着减弱了NAV当前密度（新生小鼠） 心室心肌。该提案中有两个相关的目标，这些目标将同时实现。 具体而言，此处概述的研究将检验以下假设：IFGF13有选择地调节心室NAV 电流和在产生心室动作电位的产生中起物理作用（AIM＃1）。平行线 研究将探讨以下假设：IFGF13起作用以调节稳定性，贩运和/或 NAV1.5编码的心室NAV通道的亚细胞定位（AIM＃2）。为了实现这些目标， IFGF13的表达将使用靶向基因在体外（小鼠）心室肌细胞中操纵 具有小的干扰RNA（siRNA）的“敲低”策略以及这些功能后果 对NAV（和其他）通道的特性和细胞表面表达的操作将是 决定。平行实验将在携带A的小鼠（FGF13 - / - ）分离的肌细胞上完成 FGF13基因座的目标破坏。 预计此处提出的研究将为您提供新的和根本重要的见解 IFGF的角色在心肌NAV通道的动态调节中。另外，这些结果 研究将指导未来的研究，重点是描述分子，细胞和全身的研究 令人兴奋的心肌膜动态调节涉及的机制 与SCN5A突变有关的心脏兴奋性的进化。从长远来看，预计 这些研究将为IFGF作为治疗目标的潜力提供重要的新见解。 调节遗传和获得的心律疾病中的NAV通道功能。