Regulation of Work Capacity in Cardiac Myocytes

心肌细胞工作能力的调节

• 批准号: 7862455
• 负责人: Kerry S McDonald
• 金额: $ 29.4万
• 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 2012-03-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7862455
• 关键词: Ablation; Address; Affect; Attenuated; Biochemical; Cardiac; Cardiac Myocytes; Cardiomyopathies; Contracts; Cyclic AMP-Dependent Protein Kinases; Dependence; Depressed mood; 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; 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）：本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），肌联蛋白亚型，和肌原纤维蛋白的磷酸化状态如何调节心肌细胞的功率输出产生能力。另一个目的是解决如何在两个扩张型心肌病小鼠模型中修改功率输出及其肌节长度依赖性。最后一个目标是使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。肌细胞功率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导致肌细胞功率输出降低，但这些变化背后的生化和生物物理机制尚不清楚。为了研究调节功率输出的潜在机制，将使用去皮的肌细胞制备物来直接测量肌原纤维功率输出以及肌原纤维功率输出如何通过肌节长度、肌原纤维蛋白的磷酸化以及在心力衰竭进展期间进行调节。实验的目的是测试的假设，肌节长度依赖的功率输出调制的肌节蛋白肌联蛋白的被动机械性能。另外的实验将测试中心主题，即在心力衰竭的进展期间，代偿的心脏表达更多的β-MyHC，其通过增强肌细胞功率输出的肌节长度依赖性来代偿。然而，随后过渡到心肌代偿失调，导致心力衰竭，部分原因是由于肌联蛋白亚型表达改变和肌节蛋白磷酸化状态变化导致的功率长度依赖性降低。这些想法将直接通过检查改变肌联蛋白结构/亚型，修改蛋白激酶诱导的肌原纤维磷酸化状态，扩张型心肌病影响肌细胞功率输出的肌节长度依赖性。总的来说，这项研究的结果应该有助于阐明调节正常心肌功率输出的分子机制，并提供了一个更好的理解的因素，损害心肌细胞的功率输出在患病的心脏。