Role of Myosin Binding Protein-C in the Regulation of Myocardial Contraction

摘要 所提出的实验的长期目标是了解 心肌肌球蛋白结合蛋白-C (cMyBP-C) 在心肌收缩调节中的作用。 cMyBP-C 突变导致数百万人肥厚型心肌病和心力衰竭 世界各地的人们在正常情况下 cMyBP-C 调节收缩 击败基础。然而，cMyBP-C 突变导致疾病的机制和 cMyBP-C 影响收缩的机制已完全了解。到现在为止 普遍的假设是 MyBP-C 通过以下方式可逆地限制收缩速度 与肌球蛋白结合并限制肌球蛋白头延伸远离厚层的能力 丝并经历与细丝上肌动蛋白相互作用的循环。然而， 我们实验室在本次资助的第一阶段所取得的发现挑战了这一想法，并且 表明 cMyBP-C 本身可以与肌动蛋白或其他配体结合以影响收缩。目标 这里将通过探测 cMyBP-C 介导的配体结合相互作用来测试其作用 新型分子识别特征（MoRF）在调节M-中的功能意义 cMyBP-C 的结构域，赋予 cMyBP-C N 末端与肌动蛋白的特异性结合，或者 在体外介导 N 末端的其他功能作用。了解其功能 MoRF 片段将进一步提供对 HCM 错义突变后疾病的新见解 都聚集在这个细分市场中。具体目标将 1) 映射 M 结构域 MoRF 中的残基 在体外和体内介导肌动蛋白结合和 M 结构域的其他功能效应 使用新型转基因小鼠； 2) 确定脯氨酸-丙氨酸和C1结构域是否 M 结构域外的 cMyBP-C 使用新的和 现有的转基因小鼠； 3) 定义 cMyBP-C 与薄层和厚层的结构相互作用 细丝。所提出的实验结果将为我们的功能提供新的见解 MyBP-C 以及健康和疾病中心肌收缩的调节机制。 ！

ABSTRACT The long-range goal of the proposed experiments is to understand the function of cardiac myosin binding protein-C (cMyBP-C) in the regulation of myocardial contraction. Mutations in cMyBP-C cause hypertrophic cardiomyopathy and heart failure in millions of people worldwide and under normal conditions cMyBP-C regulates contraction on a beat-to- beat basis. However, neither the mechanisms by which cMyBP-C mutations cause disease nor the mechanisms by which cMyBP-C affects contraction are completely understood. Until now the prevailing hypothesis has been that MyBP-C reversibly limits the speed of contraction by binding to myosin and restricting the ability of myosin heads to extend away from thick filaments and to undergo cycles of interaction with actin on the thin filaments. However, discoveries made by our lab during the first period of this grant challenged this idea and suggest that cMyBP-C itself can bind to actin or other ligands to influence contraction. Aims here will test the role of ligand binding interactions mediated by cMyBP-C by probing the functional significance of novel Molecular Recognition Features (MoRFs) in the regulatory M- domain of cMyBP-C that confer specific binding of the cMyBP-C N-terminus to actin or that mediate other functional effects of the N-terminus in vitro. Understanding the function of the MoRF segment will further provide new insights into disease since HCM missense mutations are clustered within this segment. Specific Aims will 1) map residues in the M-domain MoRFs that mediate actin binding and other functional effects of the M-domain in vitro and in vivo using novel transgenic mice; 2) determine whether the proline-alanine and C1 domains of cMyBP-C outside the M-domain contribute the function of cMyBP-C in vivo using new and existing transgenic mice; and 3) define structural interactions of cMyBP-C with thin and thick filaments. Results from the proposed experiments will provide new insights into the function of MyBP-C and regulatory mechanisms of myocardial contraction in health and disease. !