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.

项目摘要 /摘要 血栓栓塞性中风是房颤（AF）死亡的主要原因。当前的防止策略 AF诱导的中风，例如口服抗凝剂，具有显着的风险，并且不完全抑制中风。心房 AF的收缩力大大降低，并导致中风风险；但是，不完整的理解 调节肌节功能的机制妨碍了针对治疗方法的发展 心房收缩功能障碍。我们实验室和其他人的最新见解表明， 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因素 AF。此外，我们已经证明了蛋白质磷酸酶1调节亚基12C（PPP1R12C） AF中有助于MLC2A去磷酸化和心房低分配率。这个项目的长期目标是 确定蛋白质磷酸酶调节和催化亚基调节MLC2A的机制 磷酸化和肌丝Ca2+灵敏度，并确定MLC2A磷酸化降低的方式 有助于心房的低取结性，AF敏感性和中风。该应用的目的是 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 体内收缩性。而我们已经表明，PPP1R12C蛋白表达增加与 人AF患者和AF的小鼠模型的MLC2A去磷酸化，调节的机制 PPP1R12C表达仍然未知。此外，PPP1R12C缺失的功能意义或 药理学PPP1R12C抑制作用仍未测试。中心假设是有一个逆 PPP1R12C活性与心房收缩性之间的关系，以及抑制PPP1R12C表达或 活动将增加AF中的心房收缩力。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；瞄准2-评估 小鼠PPP1R12C的遗传敲除是否会增加心房收缩力；目标3-验证药理学 在体内修改PPP1R12C活性的方法。我们项目的创新是我们正在评估 心房低取包性，这是Virchow三合会在AF中预防中风的唯一肢体。提议 项目将首次尝试干预心房收缩底物并修改心房 体内心肌病。我们从完成目标完成后的预期结果是增强的 了解AF中心房收缩功能障碍的机制，并验证目标 增加心房收缩性并降低AF中的中风风险。