CaMKII-dependent regulation of cardiac excitability

CaMKII 依赖性心脏兴奋性调节

• 批准号: 8532036
• 负责人: Thomas Jeffrey Hund
• 金额: $ 36.3万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8532036
• 关键词: Abnormal Cell; Actins; Address; Animal Model; Ankyrins; Arrhythmia; Biogenesis; Canis familiaris; Cardiac; Cardiac Myocytes; Cell membrane; Cell physiology; Cells; Cessation of life; Complex; Data; Figs - dietary; Genetic Transcription; Heart; Heart Diseases; Heart failure; Human; Intercalated disc; Ion Channel; Link; Membrane; Membrane Proteins; Modeling; Molecular; Mus; Muscle Cells; Myocardial; Nodal; Pathway interactions; Patients; Phosphorylation; Post-Translational Protein Processing; Predisposition; Protein-Serine-Threonine Kinases; Proteins; Reagent; Regulation; Research; Role; Signal Transduction; Site; Spectrin; Sudden Death; United States; Variant; adapter protein; base; betaIV spectrin; calmodulin-dependent protein kinase II; disease phenotype; heart function; improved; innovation; insight; new therapeutic target; novel; oxidation; polypeptide; prevent; receptor; scaffold; tool; voltage

DESCRIPTION (provided by applicant): Excitable cell function depends on highly evolved local signaling domains that exert tight spatial and temporal control over post-translational modification (e.g. phosphorylation, oxidation) of ion channels, transporters and receptors. Disruption of these local signaling domains and/or alterations in post-translational modification of membrane proteins are associated with increased susceptibility to arrhythmia in congenital and acquired forms of heart disease, including heart failure. Our research seeks to understand the cellular pathways responsible for local regulation of membrane proteins in specific subcellular domains with the overall objective of generating new insight into human cardiac arrhythmia and sudden death. CaMKII is a multifunctional serine/threonine kinase that regulates a broad spectrum of critical cellular functions in heart. Despite the importance of CaMKII for heart function, little is known regarding the biogenesis of local domains to control CaMKII signaling. We recently demonstrated that the actin-associated polypeptide betaIV-spectrin serves as a novel CaMKII-anchoring protein (CaMKAP), which targets CaMKII to the intercalated disc for regulation of voltage-gated Na+ channel (Nav) function and cardiac excitability. However, the molecular pathway linking betaIV-spectrin/CaMKII to Nav1.5 at the intercalated disc, and mechanisms by which CaMKII alters Nav1.5 function remain unknown. Moreover, the role for CaMKII-dependent regulation of Nav1.5 and cell excitability in heart disease and potentially fatal electrical rhythm disturbances (arrhythmias) is unexplored. Our preliminary data indicate that betaIV-spectrin acts as a scaffold for organizing CaMKII with the adapter protein ankyrin-G and Nav1.5 at the intercalated disc. We have also identified a potential site on Nav1.5 (Ser571) responsible for CaMKII-dependent regulation of Nav function and have developed new reagents to study the role of this site in primary myocytes. Furthermore, we have identified the mechanism for a cluster of human variants adjacent to the CaMKII phosphorylation motif that confer susceptibility to arrhythmia by disrupting normal channel regulation. Finally, our preliminary results indicate that dysregulation of CaMKII-dependent phosphorylation of Nav1.5 occurs in murine and canine models of heart disease, and in failing human hearts. Collectively, these preliminary data support our central hypothesis that betaIV-spectrin organizes a local membrane domain at the cardiomyocyte intercalated disc to control CaMKII-dependent phosphorylation of Nav1.5, and that the CaMKII regulatory motif in Nav1.5 is a critical nodal point for regulating channel function in diverse forms of cardiac disease associated with arrhythmias and sudden death. We expect that targeted disruption of CaMKII/spectrin interaction will prevent CaMKII-dependent phosphorylation of Nav1.5, decrease arrhythmia burden and improve heart function in the setting of myocardial insult. We anticipate that these studies will generate new insight into organization of CaMKII signaling domains, define molecular pathways for regulation of Nav1.5 and cell excitability, and identify novel mechanisms for arrhythmias in both congenital and acquired heart disease.

描述（由申请人提供）：可兴奋细胞功能依赖于高度进化的局部信号传导结构域，其对离子通道、转运蛋白和受体的翻译后修饰（例如磷酸化、氧化）施加严格的空间和时间控制。这些局部信号结构域的破坏和/或膜蛋白翻译后修饰的改变与先天性和获得性心脏病（包括心力衰竭）中心律失常的易感性增加相关。我们的研究旨在了解负责特定亚细胞结构域中膜蛋白局部调节的细胞途径，其总体目标是对人类心律失常和猝死产生新的见解。CaMKII是一种多功能丝氨酸/苏氨酸激酶，调节心脏中的广谱关键细胞功能。尽管CaMKII对心脏功能的重要性，但关于控制CaMKII信号传导的局部结构域的生物发生知之甚少。我们最近证明，肌动蛋白相关的多肽β IV-血影蛋白作为一种新的CaMKII锚定蛋白（CaMKAP），其靶向CaMKII的闰盘的电压门控Na+通道（Nav）的功能和心脏兴奋性的调节。然而，连接betaIV-血影蛋白/CaMKII到Nav1.5在闰盘的分子途径，以及CaMKII改变Nav1.5功能的机制仍然未知。此外，Nav1.5和细胞兴奋性在心脏病和潜在致命的电节律紊乱（心律失常）中的CaMKII依赖性调节作用尚未研究。我们的初步数据表明，β IV-血影蛋白作为一个支架组织CaMKII与衔接蛋白锚蛋白-G和Nav1.5在闰盘。我们还确定了一个潜在的网站Nav1.5（Ser 571）负责CaMKII依赖性调节Nav功能，并开发了新的试剂来研究这个网站在原代心肌细胞中的作用。此外，我们已经确定了一组邻近CaMKII磷酸化基序的人类变异的机制，这些变异通过破坏正常的通道调节而使心律失常易感。最后，我们的初步结果表明，Nav1.5的CaMKII依赖性磷酸化的失调发生在小鼠和犬心脏病模型中，以及在衰竭的人类心脏中。总的来说，这些初步数据支持我们的中心假设，即β IV-血影蛋白在心肌细胞闰盘处组织局部膜结构域以控制Nav1.5的CaMKII依赖性磷酸化，Nav1.5中的CaMKII调节基序是调节与心律失常和猝死相关的各种心脏疾病中通道功能的关键节点。我们预期，靶向破坏CaMKII/血影蛋白相互作用将防止Nav1.5的CaMKII依赖性磷酸化，降低心律失常负担并改善心肌损伤情况下的心脏功能。我们预计，这些研究将产生新的洞察组织的CaMKII信号结构域，定义分子通路的Nav1.5和细胞兴奋性的调节，并确定新的机制，心律失常的先天性和后天性心脏病。