Metabolic Regulation of Sodium Channels

钠通道的代谢调节

• 批准号: 8306025
• 负责人: SAMUEL C DUDLEY
• 金额: $ 40.1万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2013-06-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8306025
• 关键词: Address; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cells; Cessation of life; Complex; Cyclic AMP-Dependent Protein Kinases; Data; Defibrillators; Devices; Down-Regulation; EFRAC; Electron Transport; Equilibrium; Heart; Heart failure; Human; Implant; Injury; Ischemia; Laboratories; Lead; Link; Mediating; Messenger RNA; Metabolic; Metabolism; Mitochondria; Modeling; Molecular; Muscle Cells; Myocardial Ischemia; Myopathy; NADH; Nicotinamide adenine dinucleotide; Pathology; Phosphorylation; Phosphotransferases; Physiological; Production; Protein Kinase C; Protein Kinase C Inhibitor; Proteins; Proteomics; Reactive Oxygen Species; Regulation; Reporting; Research; Respiration; Risk; Sarcolemma; Scheme; Signal Pathway; Sodium; Sodium Channel; Source; Sudden Death; Superoxide Dismutase; Superoxides; Techniques; Testing; base; clinically significant; heart metabolism; inhibitor/antagonist; insight; novel; prevent; psychologic; pyridine; pyridine nucleotide; research study; treatment strategy

DESCRIPTION (provided by applicant): Despite extensive research and novel treatments, conditions associated with deranged cardiac metabolism such as heart failure (HF) or ischemia are still associated with a substantial risk of arrhythmic sudden death. Cardiac injury from many causes is associated with altered metabolism and downregulation of the cardiac sodium channel (SCN5A). Recently, data demonstrated that the SCN5A was substantially and immediately modulated by pyridine nucleotides. Physiologically relevant elevations in intracellular NADH resulted in a rapid decrease in INa in both HEK cells and cardiomyocytes that was large enough to be clinically significant. The immediacy of the NADH effect on reducing INa and the lack of change in mRNA abundances under various experimental conditions suggested that the effect of NADH was post-transcriptional. Internally or externally applied NAD+ antagonized the downregulation of current seen with a rise of internal NADH. The finding that the balance of oxidized and reduced pyridine nucleotides regulates the Na+ current suggests that the metabolic state of myocytes may influence INa. The results identify a heretofore unknown regulation of cardiac Na+ channels that may help explain the link between metabolism and arrhythmic risk and may suggest that NAD+ could lessen arrhythmic risk resulting from reduced INa. This application proposes to extend these findings to better understand the mechanism whereby changes in pyridine nucleotides cause SCN5A regulation and to establish the relevance of these changes to arrhythmogenesis in myopathy models. Specific Objectives. Specific aim 1: To determine the mechanism by which NADH acts on the Na+ channel to mediate downregulation of INa. These experiments will differentiate between two leading hypotheses for how NADH mediates its effects on the Na+ channel, either by direct action on the channel complex or by causing channel isolation from the sarcolemma. Insight into Na+ channel regulation may allow mitigation of arrhythmic risk associated with low INa states. Specific aim 2: To determine which proteins are modified in the mitochondrial electron transport chain (ETC) by NADH and NAD+. As we have recently shown, the effects of NADH and NAD+ on mitochondrial ROS production are kinase dependent. Our preliminary data show that NADH activates mitochondrial ROS production via PKC, and NAD+ prevents this via PKA. Using ETC inhibitors and activators, we localized the source of ROS to either complexes I or III.17 We propose to use proteomic techniques to establish if PKA and PKC phosphorylate these complexes and whether that phosphorylation results in alteration of mitochondrial respiration, complex activity, or ROS production to better understand the mechanisms regulating mitochondrial ROS production. Specific aim 3: To determine whether NAD+ can mitigate reduced INa in ischemic and nonischemic cardiomyopathy models. Our preliminary data suggests that NAD+ may serve to mitigate arrhythmic risk in states where INa is decreased. We will test this hypothesis in two cardiomyopathy models as preliminary data for NAD+ use in humans.

描述（由申请人提供）：尽管进行了广泛的研究和新颖的治疗方法，但与心脏代谢紊乱相关的病症，例如心力衰竭（HF）或缺血，仍然与心律失常性猝死的重大风险相关。许多原因引起的心脏损伤与新陈代谢的改变和心脏钠通道 (SCN5A) 的下调有关。最近，数据表明 SCN5A 受到吡啶核苷酸的显着且立即的调节。细胞内 NADH 的生理相关升高导致 HEK 细胞和心肌细胞中 INa 迅速下降，其幅度足以具有临床意义。 NADH 对减少 INa 的直接作用以及在各种实验条件下 mRNA 丰度没有变化表明 NADH 的作用是转录后的。内部或外部施加的 NAD+ 对抗随着内部 NADH 的上升而出现的电流下调。 氧化和还原吡啶核苷酸的平衡调节Na+电流的发现表明，肌细胞的代谢状态可能影响INa。结果确定了迄今为止未知的心脏 Na+ 通道调节，这可能有助于解释代谢与心律失常风险之间的联系，并可能表明 NAD+ 可以降低因 INa 减少而导致的心律失常风险。本申请旨在扩展这些发现，以更好地理解吡啶核苷酸的变化引起SCN5A调节的机制，并确定这些变化与肌病模型中心律失常发生的相关性。具体目标。具体目标1：确定NADH作用于Na+通道介导INa下调的机制。这些实验将区分关于 NADH 如何介导其对 Na+ 通道的影响的两个主要假设，或者通过直接作用于通道复合物，或者通过导致通道与肌膜隔离。对 Na+ 通道调节的深入了解可能有助于减轻与低 INa 状态相关的心律失常风险。具体目标 2：确定线粒体电子传递链 (ETC) 中哪些蛋白质被 NADH 和 NAD+ 修饰。正如我们最近所表明的，NADH 和 NAD+ 对线粒体 ROS 产生的影响是激酶依赖性的。我们的初步数据表明，NADH 通过 PKC 激活线粒体 ROS 产生，而 NAD+ 通过 PKA 阻止这种情况。使用 ETC 抑制剂和激活剂，我们将 ROS 的来源定位到复合物 I 或 III。17 我们建议使用蛋白质组学技术来确定 PKA 和 PKC 是否磷酸化这些复合物，以及磷酸化是否会导致线粒体呼吸、复合物活性或 ROS 产生的改变，以更好地了解调节线粒体 ROS 产生的机制。具体目标 3：确定 NAD+ 是否可以减轻缺血性和非缺血性心肌病模型中 INa 的减少。我们的初步数据表明，NAD+ 可能有助于减轻 INa 减少的状态下的心律失常风险。我们将在两个心肌病模型中测试这一假设，作为 NAD+ 在人类中使用的初步数据。