Myosin Light Chain Dephosphorylation by PPP1R12C Promotes Atrial Hypocontractility and Atrial Fibrillation

PPP1R12C 的肌球蛋白轻链去磷酸化促进心房收缩力和心房颤动

• 批准号: 10394886
• 负责人: Mark D McCauley
• 金额: $ 63.1万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10394886
• 关键词: Address; Angiotensin II; Angiotensin Receptor; Anticoagulants; Arrhythmia; Atrial Fibrillation; Attenuated; Binding; Biological Assay; Blood; Cardiac; Cardiomyopathies; Catalytic Domain; Cause of Death; Chronic; Data; Endothelium; Exclusion; Functional disorder; Genetic; Genetic Transcription; Goals; Heart; Heart Atrium; Heart Diseases; Holoenzymes; Human; In Vitro; Intervention; Knock-out; Knockout Mice; Knowledge; Limb structure; Measures; Methods; Microfilaments; Mus; Mutant Strains Mice; Myocardium; Myosin ATPase; Myosin Light Chains; Oral; Outcome; Pathologic; Patients; Peptides; Pharmaceutical Preparations; Pharmacology; Phosphorylation; Play; Population; Predisposition; Prophylactic treatment; Protein Dephosphorylation; Protein phosphatase; Proteins; Pump; Reporter Genes; Risk; Role; Saline; Sarcomeres; Signal Transduction; Stroke; Stroke prevention; Structural Protein; Testing; Therapeutic; Thrombophilia; Thrombosis; Time; Triad Acrylic Resin; Validation; auricular appendage; base; cardiac magnetic resonance imaging; in vivo; inhibitor; innovation; insight; mouse model; overexpression; prevent; prophylactic; protein expression; stroke event; stroke risk; therapeutic development; thromboembolic stroke; transcription factor; valsartan

Project Summary / Abstract Thromboembolic stroke is a leading cause of death from atrial fibrillation (AF). Current strategies to prevent AF-induced stroke, such as oral anticoagulants, have significant risks and incompletely suppress stroke. Atrial contractility is significantly reduced in AF and contributes to stroke risk; however, an incomplete understanding of mechanisms regulating sarcomere function has hindered development of therapeutic approaches targeting atrial contractile dysfunction. Recent insights from our lab and others have demonstrated that hypo- phosphorylation of atrial myosin light chain (MLC2a) is a major contributor to atrial contractile dysfunction in AF. Furthermore, we have demonstrated that the protein phosphatase 1 regulatory subunit 12C (PPP1R12C) contributes to MLC2a dephosphorylation and atrial hypocontractility in AF. The long-term goal of this project is to determine the mechanisms by which protein phosphatase regulatory and catalytic subunits regulate MLC2a phosphorylation and myofilament Ca2+ sensitivity, and determine how reduced MLC2a phosphorylation contributes to atrial hypocontractility, AF susceptibility, and stroke. The objective of this application is to evaluate PPP1R12C protein expression and activity as a regulator of atrial Ca2+ sensitivity and atrial contractility in vivo. Whereas we have shown that increased PPP1R12C protein expression is associated with MLC2a dephosphorylation in human AF patients and mouse models of AF, the mechanisms regulating PPP1R12C expression remain unknown. Furthermore, the functional significance of PPP1R12C deletion or pharmacologic PPP1R12C inhibition remain untested. The central hypothesis is that there is an inverse relationship between PPP1R12C activity and atrial contractility, and that inhibition of PPP1R12C expression or activity will increase atrial contractility in AF. To test this hypothesis, three Specific Aims are proposed: Aim 1- To determine the mechanism whereby AngII signaling increases PPP1R12C expression; Aim 2- To assess whether genetic knockout of Ppp1r12c in mice increases atrial contractility; Aim 3 - To validate pharmacologic approaches to modifying PPP1R12C activity in vivo. The innovation of our project is that we are evaluating atrial hypocontractility, the only limb of Virchow's triad unaddressed for stroke prevention in AF. The proposed project would, for the first time, attempt to intervene upon the atrial contractile substrate and modify atrial cardiomyopathy in vivo. Our expected outcome from completion of the proposed Aims is an enhanced understanding of the mechanisms underlying atrial contractile dysfunction in AF, and validation of targets to increase atrial contractility and reduce stroke risk in AF.

项目概要/摘要 血栓栓塞性中风是心房颤动 (AF) 死亡的主要原因。目前的预防策略 房颤诱发的中风，例如口服抗凝剂，具有显着的风险并且不能完全抑制中风。心房 房颤患者的收缩力显着降低，增加中风风险；但理解不全面 调节肌节功能的机制阻碍了靶向治疗方法的发展 心房收缩功能障碍。我们实验室和其他实验室的最新见解表明， 心房肌球蛋白轻链（MLC2a）的磷酸化是导致心房收缩功能障碍的主要原因 AF。此外，我们还证明蛋白磷酸酶 1 调节亚基 12C (PPP1R12C) 有助于 AF 中的 MLC2a 去磷酸化和心房收缩力减退。该项目的长期目标是 确定蛋白磷酸酶调节和催化亚基调节 MLC2a 的机制 磷酸化和肌丝 Ca2+ 敏感性，并确定如何降低 MLC2a 磷酸化 导致心房收缩力减退、房颤易感性和中风。该应用程序的目的是 评估 PPP1R12C 蛋白表达和活性作为心房 Ca2+ 敏感性和心房的调节剂 体内的收缩力。然而我们已经证明 PPP1R12C 蛋白表达增加与 人类 AF 患者和 AF 小鼠模型中 MLC2a 去磷酸化及其调节机制 PPP1R12C 表达仍然未知。此外，PPP1R12C 缺失或 PPP1R12C 的药理学抑制作用尚未测试。中心假设是存在逆 PPP1R12C 活性与心房收缩力之间的关系，以及抑制 PPP1R12C 表达或 活动会增加 AF 时的心房收缩力。为了检验这一假设，提出了三个具体目标： 目标 1- 确定 AngII 信号传导增加 PPP1R12C 表达的机制；目标 2 - 评估 小鼠 Ppp1r12c 基因敲除是否会增加心房收缩力？目标 3 - 验证药理学 体内修改 PPP1R12C 活性的方法。我们项目的创新之处在于我们正在评估 心房收缩力低下，这是 Virchow 三联征中唯一未针对 AF 中风预防进行解决的问题。拟议的 该项目将首次尝试干预心房收缩基质并改变心房 体内心肌病。我们完成拟议目标的预期成果是增强 了解 AF 心房收缩功能障碍的机制，并验证目标 增加心房收缩力并降低 AF 中风风险。