Myosin ELC, a novel therapeutic target for FHC

肌球蛋白 ELC，FHC 的新型治疗靶点

基本信息

批准号：
8392246
负责人：
Danuta Szczesna-Cordary
金额：
$ 37.13万
依托单位：
UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
依托单位国家：
美国
项目类别：
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/8392246
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

项目摘要

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（申请人提供）：肌球蛋白必需轻链（ELC）是肌动球蛋白跨桥的结构成分，但对其功能或心脏特异性 N 末端 ELC 延伸对肌球蛋白相互作用的重要性知之甚少与肌动蛋白一起，促进力量和心脏功能的发展。最近发现的几种错义突变突显了 ELC 的功能重要性，这些错义突变可导致家族性肥厚型心肌病 (FHC)，这是一种以心室扩大、肌丝紊乱和心源性猝死 (SCD) 为表现的遗传性疾病。该提案将阐明 ELC 介导的 FHC 机制以及 N 端 ELC-肌动蛋白直接相互作用在正常心脏和 FHC 心脏中的作用。具体目标 1：确定 ELC 突变诱导 FHC 发育的机制。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，从而改变收缩周期和发育过程中肌球蛋白跨桥的机械（刚度、力）和/或动力学特性的力量。这项研究的重点是位于两个不同 ELC 域的两种 FHC 突变，并展示了不同的临床表型。 N 端 A57G 突变被证明会导致典型的不对称肥大和 SCD，而 C 端 E143K 突变则表现为中腔肥大、收缩期阻塞和限制性生理。我们建议确定： (1A) FHC 突变对 ELC 与 2-MHC 结合、肌球蛋白杠杆臂刚度和肌球蛋白跨桥动力学的影响。 (1B) 带皮和完整乳头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、侵入性血流动力学和 MRI 观察突变转基因小鼠心脏的年龄依赖性形态和功能。具体目标 2：探索 ELC N 末端调节肌球蛋白产生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，促进强跨桥形成，从而作为调节肌动蛋白-肌球蛋白相互作用和肌丝协同性的机制，从而调节收缩力。使用表达 N 端截短 ELC 的 Tg-43 小鼠和表达全长 ELC 野生型的 Tg-WT 的心肌制剂，我们将研究：(2A) ELC N 端对于肌球蛋白力产生能力的重要性在分子和肌纤维水平上确定。 (2B)N端ELC延伸对肌球蛋白跨桥动力学的影响。(2C)N端ELC依赖性心肌肥大发展的机制。这些研究将有助于确定 ELC 和 N 端心脏特异性 ELC 延伸在健康和 FHC 疾病心脏收缩力调节中的作用。