Myosin ELC, a novel therapeutic target for FHC

肌球蛋白 ELC，FHC 的新型治疗靶点

• 批准号: 8586553
• 负责人: Danuta Szczesna-Cordary
• 金额: $ 37.75万
• 依托单位: UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-12-01 至 2015-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8586553
• 关键词: ATP phosphohydrolase; ATP-G-actin; Actins; Actomyosin; Address; Affect; Aging; Alanine; Amino Acids; Animal Model; Asians; Basic Science; Binding; Biological Assay; C-terminal; Cardiac; Cardiac Muscle Contraction; Cardiac Myosins; Development; Disease; Echocardiography; Familial Hypertrophic Cardiomyopathy; Family suidae; Fibrosis; Filament; Fluorescence; Foundations; Gene Mutation; Generations; Glutamic Acid; Glycine; Goals; Head; Heart; Heart Diseases; Heart Hypertrophy; Hereditary Disease; Histopathology; Human; Hypertrophy; In Vitro; Induced Mutation; Kinetics; Lead; Length; Light; Link; Lysine; Magnetic Resonance Imaging; Malignant - descriptor; Measurement; Measures; Mechanics; Mediating; Microfilaments; Missense Mutation; Molecular; Molecular Motors; Morphology; Motor; Movement; Mus; Muscle; Muscle Contraction; Muscle Fibers; Mutate; Mutation; Myocardium; Myofibrils; Myosin ATPase; Myosin Alkali Light Chains; Myosin Heavy Chains; N-terminal; Obstruction; Outcome; Patients; Performance; Phenotype; Physiological; Physiology; Play; Positioning Attribute; Preparation; Property; Protein Isoforms; Proteins; Publishing; Regulation; Role; Sarcomeres; Sedimentation process; Site; Skeletal Muscle; Skin; Smooth Muscle; Structure; Systole; Testing; Thick Filament; Thin Filament; Transgenic Animals; Transgenic Mice; Transgenic Organisms; Tropomyosin; Troponin; Ventricular; age related; arm; base; cell motility; clinical phenotype; hemodynamics; improved; in vivo; mutant; myosin-binding protein C; new therapeutic target; novel; optical traps; papillary muscle; protein protein interaction; reconstitution; research study; sudden cardiac death; young adult

DESCRIPTION (provided by applicant): The myosin essential light chain (ELC) is a structural component of the actomyosin cross-bridge, but little is known about its function or the significance of the cardiac specific N-terminal ELC extension on the interaction of myosin with actin, development of force and heart performance. The functional importance of ELC is highlighted by the recent identification of several missense mutations shown to cause Familial Hypertrophic Cardiomyopathy (FHC), a genetic disorder manifested by ventricular enlargement, myofilament disarray and sudden cardiac death (SCD). This proposal will elucidate the mechanisms of ELC-mediated FHC and the role of the direct N-terminal ELC-actin interaction in the normal and FHC heart. SPECIFIC AIM 1: DETERMINE THE MECHANISM FOR THE ELC-MUTATION INDUCED DEVELOPMENT OF FHC. We hypothesize that ELC mutations may lead to FHC by affecting the ability of the ELC to form stable structures with the MHC, thus altering the mechanical (stiffness, force) and/or kinetic properties of the myosin cross-bridge during the contractile cycle and development of force. This study is focused on two FHC- mutations localized in two different ELC domains and demonstrating different clinical phenotypes. The N- terminal A57G mutation was shown to cause a classic asymmetric hypertrophy and SCD, and the C-terminal E143K mutation, which presented with mid-cavity hypertrophy, obstruction in systole and restrictive physiology. We propose to determine: (1A) The effect of FHC mutations on the binding of ELC to the 2-MHC, myosin lever arm stiffness and myosin cross-bridge kinetics. (1B) The contractile properties of the mutated myocardium in skinned and intact papillary muscle fibers. (1C) The age-dependent morphology and function of mutated transgenic mouse hearts by histopathology, echocardiography, invasive hemodynamics and MRI. SPECIFIC AIM 2: EXPLORE THE MECHANISMS BY WHICH THE N-TERMINUS OF ELC REGULATES MYOSIN FORCE GENERATING CAPABILITY AND CARDIAC MUSCLE CONTRACTION. We hypothesize that the N- terminus of ELC interacts with the actin-tropomyosin-troponin filaments to promote strong cross-bridge formation~ thus it serves as a mechanism to modulate the actin-myosin interaction and myofilament cooperativity, thereby regulating contractile force. Using cardiac muscle preparations from Tg- 43 mice expressing the N-terminal truncated ELC and Tg-WT expressing the full length ELC wild-type, we will study: (2A) the importance of the N-terminus of ELC for myosin force generating capability determined at the molecular and muscle fiber levels. (2B) the effect of the N-terminal ELC extension on myosin cross-bridge kinetics.(2C) The mechanism of the N-terminus ELC-dependent development of cardiac hypertrophy. These studies will help to determine the role(s) of the ELC and the N-terminal cardiac specific ELC extension in the regulation of contractile force in healthy and FHC-diseased hearts.

描述（由申请人提供）：肌球蛋白必需轻链（myosin essential light chain， ELC）是肌动蛋白交叉桥的结构成分，但其功能和心脏特异性n端ELC延伸对肌动蛋白与肌动蛋白相互作用、力的发展和心脏性能的意义尚不清楚。最近发现的几种导致家族性肥厚性心肌病（FHC）的错义突变突出了ELC的功能重要性，家族性肥厚性心肌病是一种遗传性疾病，表现为心室增大、肌丝紊乱和心源性猝死（SCD）。本研究将阐明elc介导的FHC机制以及n端直接ELC-actin相互作用在正常和FHC心脏中的作用。具体目的1：确定elc突变诱导fhc发生的机制。我们假设ELC突变可能通过影响ELC与MHC形成稳定结构的能力而导致FHC，从而改变肌球蛋白桥在收缩周期和力发展过程中的机械（刚度、力）和/或动力学特性。本研究的重点是两个FHC突变定位于两个不同的ELC结构域，并表现出不同的临床表型。N端A57G突变导致典型的不对称肥大和SCD， c端E143K突变表现为腔中肥大、收缩阻塞和限制性生理。我们拟确定：（1A） FHC突变对ELC与2-MHC结合、肌凝蛋白杠杆臂刚度和肌凝蛋白过桥动力学的影响。（1B）剥皮和完整乳头状肌纤维中突变心肌的收缩特性。（1C）通过组织病理学、超声心动图、有创血流动力学和MRI观察转基因突变小鼠心脏的年龄依赖性形态和功能。具体目的2：探讨elc n端调控肌球蛋白生成能力和心肌收缩的机制。我们假设ELC的N端与肌动蛋白-原肌球蛋白-肌钙蛋白丝相互作用，促进强交叉桥的形成，因此它可以作为调节肌动蛋白-肌球蛋白相互作用和肌丝协同性的机制，从而调节收缩力。利用表达n端截断ELC的Tg- 43小鼠心肌制剂和表达全长ELC野生型的Tg- wt小鼠心肌制剂，我们将研究：（2A）在分子和肌纤维水平上确定ELC n端对肌球蛋白生成能力的重要性。（2B） n端ELC延伸对肌球蛋白过桥动力学的影响。（2C） n端elc依赖性心肌肥厚发生的机制。这些研究将有助于确定ELC和n端心脏特异性ELC延伸在调节健康和fhc病变心脏收缩力中的作用。