Metabolic Regulation of Sodium Channels

钠通道的代谢调节

• 批准号: 8186151
• 负责人: SAMUEL C DUDLEY
• 金额: $ 41.48万
• 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 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8186151
• 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. PUBLIC HEALTH RELEVANCE: Despite extensive research and novel treatments, conditions associated with deranged cardiac metabolism such as heart failure or ischemia are still associated with a substantial risk of sudden death. The finding that the balance of oxidized and reduced pyridine nucleotides regulates the sodium current suggests that the heart metabolic state influences sodium current. Our results identify a heretofore unknown regulation of cardiac sodium channels that may help explain the link between metabolism and sudden death and may suggest that NAD+ could lessen death risk resulting from reduced sodium current.

描述（由申请人提供）：尽管进行了广泛的研究和新的治疗，但与心脏代谢紊乱相关的疾病，如心力衰竭（HF）或缺血，仍与心肌猝死的重大风险相关。许多原因引起的心脏损伤与心脏钠通道（SCN 5A）的代谢改变和下调有关。最近，数据表明，SCN5A是基本上和立即由吡啶核苷酸调制。细胞内NADH的生理相关升高导致HEK细胞和心肌细胞中INa的快速降低，其大到足以具有临床意义。在各种实验条件下，NADH对降低INa的作用的即时性和mRNA丰度的缺乏变化表明，NADH的作用是转录后的。内部或外部应用的NAD+拮抗电流的下调，内部NADH的上升。 氧化和还原的吡啶核苷酸的平衡调节Na+电流的发现表明，心肌细胞的代谢状态可能会影响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和心肌梗死风险之间的联系，并可能表明NAD+可以降低由INa降低引起的心肌梗死风险。本申请提出扩展这些发现，以更好地理解吡啶核苷酸的变化引起SCN 5A调节的机制，并建立这些变化与肌病模型中的肌纤维化的相关性。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。这些实验将区分两个主要的假设，NADH如何介导其对Na+通道的影响，通过直接作用于通道复合物或通过引起通道从肌膜隔离。对Na+通道调节的深入了解可能有助于缓解与低INa状态相关的脑血管病风险。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的产生，NAD+通过PKA阻止这一点。使用ETC抑制剂和激活剂，我们将ROS的来源定位于复合物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的降低。我们的初步数据表明，NAD+可能有助于减轻INa降低的州的糖尿病风险。我们将在两种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。 公共卫生相关性：尽管有广泛的研究和新的治疗方法，与心脏代谢紊乱有关的疾病，如心力衰竭或缺血，仍然与猝死的重大风险有关。氧化和还原吡啶核苷酸的平衡调节钠电流的发现表明心脏代谢状态影响钠电流。我们的研究结果确定了迄今为止未知的心脏钠通道调节，这可能有助于解释代谢和猝死之间的联系，并可能表明NAD+可以降低钠电流减少导致的死亡风险。