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基因突变导致数百万人肥厚性心肌病和心力衰竭 全世界的人，在正常情况下，cMyBP-C调节节拍对- 节拍基数。然而，cMyBP-C突变导致疾病的机制或 CMyBP-C影响收缩的机制是完全理解的。到目前为止 普遍的假设是，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部向外延伸的能力 并与细丝上的肌动蛋白发生循环相互作用。然而， 我们实验室在这笔赠款的第一阶段所做的发现挑战了这一想法，并 提示cMyBP-C本身可以与肌动蛋白或其他配体结合来影响收缩。目标 这里将通过探测cMyBP-C介导的配体结合作用来测试cMyBP-C的作用 新的分子识别特征(Morf)在调节分子生物学中的功能意义 CMyBP-C的结构域，赋予cMyBP-C N末端与肌动蛋白或肌动蛋白的特异性结合 在体外介导N-末端的其他功能效应。了解的功能 由于HCM错义突变，MORF片段将进一步提供对疾病的新见解 都聚集在这个细分市场中。特定的目标将1)映射M-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 使用新的转基因小鼠；2)确定Pro-丙氨酸和C1域是否 M结构域外的cMyBP-C在体内通过使用新的和 现有的转基因小鼠；以及3)确定cMyBP-C与瘦和厚的结构相互作用 细丝。拟议中的实验结果将为我们提供新的见解，了解 MyBP-C与健康和疾病中心肌收缩的调节机制。 好了！

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. !