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

摘要 拟议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的突变导致数百万人的肥厚型心肌病和心力衰竭。 在正常情况下，cMyBP-C调节心跳收缩， beat基础然而，cMyBP-C突变引起疾病的机制和 cMyBP-C影响收缩的机制已完全清楚。直到现在 流行的假设是MyBP-C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肌球蛋白的能力， 并经历与微丝上的肌动蛋白的相互作用的周期。然而，在这方面， 我们实验室在第一阶段的发现挑战了这一观点， 提示cMyBP-C本身可以与肌动蛋白或其他配体结合以影响收缩。旨在 这里将通过探测cMyBP-C介导的配体结合相互作用的作用， 新的分子识别特征（MoRFs）在调节M- cMyBP-C的结构域，其赋予cMyBP-C N-末端与肌动蛋白的特异性结合，或 在体外介导N-末端的其他功能作用。了解的功能 MoRF部分将进一步提供新的见解疾病，因为HCM错义突变 都集中在这个部分。具体目标将：1）对M结构域MoRF中的残基进行定位 其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 使用新的转基因小鼠; 2）确定是否脯氨酸-丙氨酸和C1结构域的 在M结构域之外的cMyBP-C使用新的和新的方法在体内贡献cMyBP-C的功能。 现有的转基因小鼠;和3）定义cMyBP-C与薄和厚的结构相互作用 细丝。从拟议的实验结果将提供新的见解的功能 MyBP-C和健康和疾病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. !