Functional consequences of FHC mutations in cardiac MyBPC

心脏 MyBPC 中 FHC 突变的功能后果

• 批准号: 9973440
• 负责人: Julian Stelzer
• 金额: $ 59.84万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-02-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9973440
• 关键词: Accounting; Actins; Actomyosin; Acute; Address; Adolescent and Young Adult; Affect; Agonist; Amino Acid Substitution; Animals; Anisotropy; Behavior; Binding; C10; Cardiac; Cardiac Muscle Contraction; Cardiac Myocytes; Cardiac Myosins; Cardiomyopathies; Computer Models; Data; Defect; Development; Disease; Disease Progression; Exercise; Familial Hypertrophic Cardiomyopathy; Fiber; Filament; Fluorescence Resonance Energy Transfer; Foundations; Gene Transfer; Generations; Goals; Heart; Heart Diseases; Human; Hypertrophic Cardiomyopathy; Impairment; Individual; Infusion procedures; Inherited; Kinetics; Knowledge; Length; Ligand Binding; Link; Maps; Measurement; Mechanics; Mediating; Microfilaments; Missense Mutation; Molecular; Morphology; Movement; Mus; Muscle function; Mutation; Myocardium; Myosin ATPase; N-terminal; Nonmuscle Myosin Type IIA; Nucleic Acid Regulatory Sequences; Patients; Physiology; Play; Property; Protein Fragment; Proteins; Regulation; Role; Rotation; Sarcomeres; Severity of illness; Skin; Structure; Sudden Death; Testing; Therapeutic; Therapeutic Intervention; Thick Filament; Time; Ventricular; Workload; atomic interactions; base; citrate carrier; design; disease-causing mutation; efficacy testing; functional disability; heart function; hemodynamics; improved; in vivo; induced pluripotent stem cell; insight; interdisciplinary approach; mutant; myosin-binding protein C; novel; novel strategies; novel therapeutics; phosphorescence; sensor; simulation; sudden cardiac death; treatment strategy; young adult

The long-range goal of this proposal is to define the mechanisms by which mutations in cardiac myosin binding protein C (MyBPC) cause hypertrophic cardiomyopathy (HCM), a disease that affects up to 1 in 200 individuals, and is the leading cause of sudden death in young adults. Nearly 60% of HCM cases are due to familial inheritance (FHC) of an autosomal dominant disorder caused by mutations in sarcomeric proteins. Mutations in MyBPC are among the most common causes of FHC accounting for half of all known cases. Because MyBPC is a critical modulator of actomyosin interactions, the initial functional deficit caused by mutations in MyBPC is expected to manifest as a defect in the regulation of cardiac muscle contraction at the myofilament level. Whereas 60% of MyBPC truncation mutations are expected to cause haploinsufficiency, the remaining 40% of MyBPC mutations are missense mutations, which are expected to produce full-length MyBPC. A large number of these missense mutations are located in the central domains of MyBPC (i.e., C3-C7), which have no specific known function, and thus it is unclear how FHC mutations located in this region of MyBPC cause disease. Our limited understanding of these critical mechanisms severely limits options for therapeutic intervention for FHC patients. Our preliminary data provide novel evidence that addresses our gap in knowledge and have identified two important regulatory regions within the C4 and C5 domains of MyBPC that modulate cardiac muscle contractile function. Based on these novel observations we have devised an experimental plan that is designed to elucidate molecular mechanisms by which these key regions contribute to regulation of contractile function and how FHC mutations alter this regulation. We have devised a multidisciplinary approach that spans from computational modeling of atomic interactions to whole animal physiology which will accomplished in three principal aims designed to: 1) Establish the functional effects of central domain MyBPC FHC mutations on the magnitude and rate of force in cardiac fibers isolated from mouse hearts expressing HCM causing mutations, and utilize molecular dynamic simulations to elucidate the molecular mechanisms of altered function. 2) Define how MyBPC mutations alter actin and myosin binding properties and rotational dynamics using TPA and FRET based sensors, and 3) Determine the in vivo functional consequences of MyBPC FHC mutations in MyBPC by assessing ventricular contractile and hemodynamic function, and test the efficacy of a MyBPC-specific AAV9 gene-transfer rescue that normalizes contractile function. Parallel studies will utilize FHC patient-specific induced pluripotent stem cell cardiomyocytes (iPSC-CM) to determine how these mutations cause disease in humans. It is expected that results from these integrative studies will provide novel insights of the underlying mechanisms by which mutations in MyBPC cause disease and will aid in the development of novel therapeutic strategies for treatment MyBPC related HCM.

该提案的长期目标是确定心肌肌球蛋白结合突变的机制 蛋白 C (MyBPC) 会导致肥厚型心肌病 (HCM)，这种疾病影响多达二百分之一的人， 并且是年轻人猝死的主要原因。近 60% 的 HCM 病例是由于家族遗传 由肌节蛋白突变引起的常染色体显性遗传（FHC）。突变在 MyBPC 是 FHC 最常见的原因之一，占所有已知病例的一半。因为MyBPC 是肌动球蛋白相互作用的关键调节剂，MyBPC 突变引起的初始功能缺陷是 预计表现为肌丝水平心肌收缩调节的缺陷。 虽然 60% 的 MyBPC 截短突变预计会导致单倍体不足，但其余 40% MyBPC 突变是错义突变，预计会产生全长 MyBPC。数量很大 这些错义突变位于 MyBPC 的中央结构域（即 C3-C7），其没有特异性 功能已知，因此尚不清楚位于 MyBPC 该区域的 FHC 突变如何导致疾病。我们的 对这些关键机制的了解有限，严重限制了 FHC 治疗干预的选择 患者。我们的初步数据提供了新的证据，解决了我们的知识差距，并确定了 MyBPC 的 C4 和 C5 结构域内两个重要的调节心肌的调节区域 收缩功能。基于这些新颖的观察结果，我们设计了一个实验计划 阐明这些关键区域有助于调节收缩功能的分子机制 以及 FHC 突变如何改变这种调节。我们设计了一种多学科方法，涵盖 原子相互作用与整个动物生理学的计算模型将在三个时间内完成 主要目标旨在： 1) 确定中央域 MyBPC FHC 突变对 从表达引起突变的 HCM 的小鼠心脏中分离出的心肌纤维的力的大小和速率， 并利用分子动力学模拟来阐明功能改变的分子机制。 2）定义 MyBPC 突变如何使用 TPA 和 FRET 改变肌动蛋白和肌球蛋白的结合特性和旋转动力学 3) 通过以下方式确定 MyBPC FHC 突变在 MyBPC 中的体内功能后果： 评估心室收缩和血流动力学功能，并测试 MyBPC 特异性 AAV9 的功效 使收缩功能正常化的基因转移救援。平行研究将利用 FHC 患者特异性诱导 多能干细胞心肌细胞 (iPSC-CM) 以确定这些突变如何导致人类疾病。它 预计这些综合研究的结果将为潜在机制提供新的见解 MyBPC 中的突变会导致疾病，并将有助于开发新的治疗策略 治疗MyBPC相关的HCM。