Evaluating NAD Supplementation as a Novel Treatment for Arrhythmias

评估 NAD 补充剂作为心律失常的新型治疗方法

• 批准号: 9765003
• 负责人: Charles M Brenner
• 金额: $ 60.59万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9765003
• 关键词: Acetylation; Action Potentials; Affect; Arrhythmia; Binding; Binding Proteins; Bioavailable; Bioenergetics; Brugada syndrome; Cardiac; Cardiac Myocytes; Cell Line; Cell membrane; Cells; Characteristics; DNA Damage; Data; Deacetylation; Diet; Dihydroxyacetone Phosphate; Dilated Cardiomyopathy; Disease; Dose; Electrocardiogram; Electrophysiology (science); Engineering; Enzymes; Gel; Genes; Genetic Transcription; Glycerol-3-Phosphate Dehydrogenase; Goals; Heart; Heart Atrium; Heart failure; In Vitro; Inherited; Ion Channel; Laboratories; Mediating; Membrane; Metabolic; Metabolism; Mus; Muscle Cells; Mutation; Myocardial; NADH; Neonatal; Niacinamide; Oxidation-Reduction; Oxidative Phosphorylation; Oxidoreductase; Pharmacology; Phosphorylation; Play; Poly(ADP-ribose) Polymerases; Post-Translational Protein Processing; Predisposition; Property; RNA Splicing; Rattus; Reactive Oxygen Species; Reporting; Role; SIRT1 gene; Signal Transduction; Sirtuins; Sodium; Sodium Channel; Structure; Sudden Death; Sudden infant death syndrome; Supplementation; Syndrome; System; Testing; Translations; age related; alpha Actinin; alpha-glycerophosphoric acid; in vivo; inhibitor/antagonist; inorganic phosphate; loss of function mutation; metabolome; mouse model; nicotinamide-beta-riboside; novel; prevent; response; trafficking; treatment effect

The inward depolarizing Na+ current (INa) through the cardiac Na+ channel Nav1.5, encoded by SCN5A, plays a critical role in regulating the action potential of myocytes in the heart. Nav1.5 post- translational modifications (PTMs) and binding proteins can alter channel abundance and/or electrophysiological properties. Loss of function mutations in SCN5A cause inherited arrhythmia syndromes including Brugada syndrome (BrS) and conduction system disease by changes in transcription, translation, channel properties and membrane trafficking. Alterations in Nav1.5 can also exacerbate arrhythmias in common acquired conditions such as heart failure. NAD+ and NADH are critical regulators of myocardial bioenergetics and redox state, and NAD+ is a required substrate for sirtuins that regulate acetylation. Our laboratory reported that mutations in the NAD+/NADH dependent enzyme Gylcerol-3 Phosphate Dehydrogenase-1 Like (GPD1-L) cause BrS by altering Nav1.5 membrane trafficking. We and others then showed that NAD+ increases INa in cell lines and cardiac myocytes, at least in part through changes in reactive oxygen species (ROS) and PKC- mediated phosphorylation in the intracellular Nav1.5 Domain III-IV linker. We have engineered Gpd1l- targeted mice that have decreased INa, conduction disease, arrhythmias and altered Nav1.5 PTMs. Nicotinamide Riboside (NR), a highly bioavailable NAD+ precursor, increases INa in heterologous expression systems and myocytes, and shortens QRS duration in mice. The mechanism(s) by which NAD+ supplementation alters Nav1.5 membrane trafficking and INa remains unclear. In addition, how multiple PTMs alter Nav1.5 and INa in a coordinated manner has not been studied. The central hypothesis of this proposal is that cellular metabolism alters the NAD+ metabolome, regulating Nav1.5 by coordinated interactions of PTMs and binding proteins that act at the Nav1.5 Domain III-IV linker. To test this hypothesis, we will 1) Determine how NAD+ precursors and inhibitors modify the NAD+ metabolome, redox state, Nav1.5 PTMs, INa and arrhythmias using cardiac myocytes and mouse models; 2) Determine whether NAD+ precursors act in a coordinated manner at the Nav1.5 Domain III-IV linker via SIRT1-mediated deacetylation, PKC-mediated phosphorylation and α-actinin 2 binding; and 3) Identify the Nav1.5 PTMs modulated by GPD1-L. The primary goal of this proposal is to identify the mechanisms by which NAD+ metabolism affects Nav1.5 expression and function. Ultimately, we hope to determine whether increasing membrane Nav1.5 with NAD+ precursors or other metabolic modulators can prevent arrhythmias in inherited Na+ channel deficiency syndromes and in more common conditions such as heart failure.

通过心脏 Na+ 通道 Nav1.5 的内向去极化 Na+ 电流 (INa)，编码为 SCN5A 在调节心脏心肌细胞动作电位方面发挥着关键作用。 Nav1.5后 翻译修饰 (PTM) 和结合蛋白可以改变通道丰度和/或 电生理特性。 SCN5A 功能缺失突变导致遗传性心律失常 综合症，包括布鲁格达综合症（BrS）和传导系统疾病 转录、翻译、通道特性和膜运输。 Nav1.5 的改动还可以 加剧心力衰竭等常见获得性疾病的心律失常。 NAD+和NADH是心肌生物能和氧化还原状态的关键调节因子，NAD+是 调节乙酰化的去乙酰化酶所需的底物。我们的实验室报告说，突变 NAD+/NADH 依赖性酶 Gylcerol-3 磷酸脱氢酶 1 样 (GPD1-L) 通过以下方式引起 BrS 改变 Nav1.5 膜运输。我们和其他人随后证明 NAD+ 会增加细胞系中的 INa 和心肌细胞，至少部分是通过活性氧 (ROS) 和 PKC 的变化- 介导细胞内 Nav1.5 结构域 III-IV 连接子的磷酸化。我们设计了 Gpd1l- 针对 INa 降低、传导疾病、心律失常和 Nav1.5 PTM 改变的小鼠。 烟酰胺核苷 (NR) 是一种高生物利用度的 NAD+ 前体，可增加异源体内的 INa 表达系统和肌细胞，并缩短小鼠的 QRS 持续时间。其机制 NAD+ 补充剂会改变 Nav1.5 膜运输，而 INa 仍不清楚。另外，如何 尚未研究多个 PTM 以协调的方式改变 Nav1.5 和 INa。 该提案的中心假设是细胞代谢改变 NAD+ 代谢组， 通过 PTM 和作用于 Nav1.5 的结合蛋白的协调相互作用来调节 Nav1.5 结构域 III-IV 接头。为了检验这一假设，我们将 1) 确定 NAD+ 前体和抑制剂如何 使用心肌细胞修改 NAD+ 代谢组、氧化还原状态、Nav1.5 PTM、INa 和心律失常 和小鼠模型； 2) 确定NAD+前体是否在Nav1.5以协调的方式起作用 通过 SIRT1 介导的脱乙酰化、PKC 介导的磷酸化和 α-肌动蛋白 2 实现结构域 III-IV 连接子 绑定； 3) 识别 GPD1-L 调节的 Nav1.5 PTM。 该提案的主要目标是确定 NAD+ 代谢影响的机制 Nav1.5的表达和功能。最终，我们希望确定是否增加膜 Nav1.5 与 NAD+ 前体或其他代谢调节剂可以预防遗传性 Na+ 的心律失常 通道缺陷综合征以及心力衰竭等更常见的疾病。