Regulation of Work Capacity in Cardiac Myocytes

心肌细胞工作能力的调节

• 批准号: 7626488
• 负责人: Kerry S McDonald
• 金额: $ 29.31万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7626488
• 关键词: Ablation; Address; Affect; Attenuated; Biochemical; Cardiac; Cardiac Myocytes; Cardiomyopathies; Contracts; Cyclic AMP-Dependent Protein Kinases; Dependence; Dilated Cardiomyopathy; Disease; Goals; Heart; Heart Diseases; Heart failure; Laboratories; Lateral; Left Ventricular Function; Length; Measurement; Measures; Mechanics; Mediating; Microfilaments; Molecular; Muscle Cells; Myocardial; Myocardium; Myofibrils; Myosin Heavy Chains; Output; Performance; Phosphorylation; Phosphorylation Site; Physiological; Preparation; Property; Protein Isoforms; Protein Kinase; Proteins; Pump; Records; Regulation; Research Personnel; Sarcomeres; Series; Site; Skin; Staging; Structure; Testing; Thick; Thin Filament; Transgenic Animals; Up-Regulation; Work; blood pump; connectin; depressed; design; enhancing factor; extracellular; mouse model; myosin-binding protein C; novel; overexpression; programs; research study

DESCRIPTION (provided by applicant): The overall purpose of this project is to understand the cellular and sub-cellular mechanisms that determine the work capacity of the heart. The specific aims of this study include determining how physiological factors including sarcomere length, myosin heavy chain (MyHC), titin isoforms, and phosphorylation status of myofibrillar proteins modulate the power output generating capacity of cardiac myocytes. An additional aim addresses how power output and its sarcomere length dependence are modified in two mouse models of dilated cardiomyopathy. A final aim uses transgenic animals to determine the specific phosphorylation sites that are responsible for PKA and PKC modulation of power output. Myocyte power output is of utmost importance in maintaining the pump capacity of the ventricles and diseases leading to heart failure yield depressed myocyte power output yet the biochemical and biophysical mechanisms underlying these changes are unknown. To investigate potential mechanism regulating power output a skinned myocyte preparation will be used to directly measure myofibrillar power output and how it is modulated by sarcomere length, phosphorylation of myofibrillar proteins, and during the progression of heart failure. Experiments are designed to test the hypothesis that sarcomere length dependence of power output is modulated by passive mechanical properties of the sarcomeric protein titin. Additional experiments will test the central theme that during the progression of heart failure compensated hearts express more (3-MyHC, which is compensatory by enhancing sarcomere length dependence of myocyte power output. However, the subsequent transition to myocardial decompensation that leads to heart failure arises, in part, from depressed length dependence of power resulting from altered titin isoform expression and changes in the phosphorylation status of sarcomeric proteins. These ideas will be directly addressed by examining how altered titin structure/isoforms, modified protein kinase-induced phosphorylation status of myofibrils, and dilated cardiomyopathy affects sarcomere length dependence of myocyte power output. Overall, results from this study should help elucidate the molecular mechanisms that regulate power output in normal myocardium and provide a better understanding of the factors that impair myocyte power output in diseased hearts.

描述（由申请人提供）：这个项目的总体目的是了解决定心脏工作能力的细胞和亚细胞机制。本研究的具体目的包括确定生理因素，包括肌节长度、肌球蛋白重链（MyHC）、肌球蛋白同型体和肌原纤维蛋白的磷酸化状态如何调节心肌细胞的能量输出生成能力。另一个目的是研究两种扩张型心肌病小鼠模型中功率输出及其肌节长度依赖性是如何改变的。最终目的是利用转基因动物来确定负责PKA和PKC调节功率输出的特定磷酸化位点。心肌细胞能量输出对于维持心室的泵送能力至关重要，导致心力衰竭的疾病会导致心肌细胞能量输出下降，但这些变化背后的生化和生物物理机制尚不清楚。为了研究调节能量输出的潜在机制，将使用一种剥皮的肌细胞制剂来直接测量肌原纤维的能量输出，以及它是如何被肌节长度、肌原纤维蛋白磷酸化和心力衰竭的进展所调节的。实验的目的是测试假设，肌节长度依赖的功率输出是由肌节蛋白titin的被动机械特性调制。进一步的实验将验证中心主题，即在心力衰竭的进展过程中，代偿性心脏表达更多（3-MyHC），这是通过增强肌细胞能量输出对肌节长度的依赖性来代偿的。然而，随后过渡到导致心力衰竭的心肌失代偿，部分原因是由于titin异构体表达改变和肌体蛋白磷酸化状态改变导致的功率长度依赖性降低。这些想法将通过检查改变的titin结构/同种异构体、修饰的蛋白激酶诱导的肌原纤维磷酸化状态和扩张型心肌病如何影响肌细胞功率输出的肌节长度依赖性来直接解决。总的来说，这项研究的结果应该有助于阐明调节正常心肌能量输出的分子机制，并提供更好地理解损害病变心脏心肌细胞能量输出的因素。