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.

这项提议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）引起肥厚型心肌病（HCM），这是一种影响高达1/200个体的疾病， 是年轻人猝死的主要原因。近60%的HCM病例是由于家族性 肌节蛋白突变引起的常染色体显性遗传（FHC）。突变 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 预期表现为在肌丝水平调节心肌收缩的缺陷。 而60%的MyBPC截短突变预计会导致单倍不足，其余40%的MyBPC截短突变预计会导致单倍不足。 MyBPC突变是错义突变，预计会产生全长MyBPC。大量 这些错义突变中的一个位于MyBPC的中心结构域（即，C3-C7），没有特异性 目前还不清楚位于MyBPC这一区域的FHC突变是如何引起疾病的。我们 对这些关键机制的有限理解严重限制了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结构域中调节心肌的两个重要调节区域 收缩功能基于这些新的观察，我们设计了一个实验计划， 阐明这些关键区域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的方法， 原子相互作用的计算模型，以整个动物生理学，这将在三个完成 设计的主要目的是：1）确定MyBPC中心结构域FHC突变对 从表达引起突变的HCM的小鼠心脏分离的心脏纤维中的力的大小和速率， 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 使用TPA和FRET研究MyBPC突变如何改变肌动蛋白和肌球蛋白结合特性和旋转动力学 基于传感器，和3）通过以下方法确定MyBPC中MyBPC FHC突变的体内功能后果： 评估心室收缩和血液动力学功能，并测试MyBPC-specific AAV 9 恢复收缩功能的基因转移拯救。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中的突变导致疾病，并将有助于开发新的治疗策略， 治疗MyBPC相关HCM。