The Role of Cardiomyopathic Troponin C Mutations in Skeletal and Cardiac Muscle C

心肌病肌钙蛋白 C 突变在骨骼肌和心肌 C 中的作用

• 批准号: 8532964
• 负责人: Jose Renato Pinto
• 金额: $ 23.27万
• 依托单位: FLORIDA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-20 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8532964
• 关键词: ATP phosphohydrolase; Actomyosin; Address; Affect; Affinity; Arrhythmia; Binding; Body Weight; Buffers; Calcium; Cardiac; Cardiac Muscle Contraction; Cardiomyopathies; Chelating Agents; Circular Dichroism; Complex; Congestive Heart Failure; Development; Dilated Cardiomyopathy; Disease; Dissociation; Fiber; Fibrosis; Fluorescence; Functional disorder; Generations; Genes; Grant; Heart; Heart Diseases; Hereditary Disease; Hypertrophic Cardiomyopathy; In Situ; In Vitro; Investigation; Kinetics; Knock-in Mouse; Knowledge; Label; Laboratories; Lead; Link; Measurement; Measures; Microfilaments; Molecular; Monitor; Morphology; Muscle; Muscle Cells; Muscle Contraction; Muscle Fibers; Mutation; Myocardium; Myopathy; Papillary; Patients; Phenotype; Physiological; Play; Process; Property; Proteins; Recombinants; Regulation; Relaxation; Reporting; Role; Skeletal Muscle; Skeletal system; Skin; Soleus Muscle; Striated Muscles; Structure; System; Thick Filament; Thin Filament; Troponin; Troponin C; Troponin I; Troponin T; Ventricular; in vivo; innovation; insight; mouse model; mutant; novel strategies; protein protein interaction; reconstitution; research study; sensor; skeletal; skeletal abnormality; stopped-flow fluorescence; sudden cardiac death; therapeutic development

Project Summary The cardiac troponin complex (CTn) is made up of cardiac troponin T (CTnT), that attaches the complex to the thin filament; cardiac troponin I (CTnI), involved in the inhibition of muscle contraction and cardiac/slow skeletal troponin C (CTnC), that binds Ca2+ and triggers contraction. Altogether, the CTn, regulates muscle contraction, i.e., Ca2+ sensitivity of force development, maximal force development and basal force. Cardiac/Slow Skeletal Troponin C (C/SSTnC) is the only component of CTn that is expressed and present in both cardiac and slow skeletal muscles. It is considered the primary Ca2+ sensor of striated muscle and has been a target of Hypertrophic (HCM) and Dilated (DCM) Cardiomyopathies. HCM or DCM are genetic disorders caused by the mutations in the TnC gene that are characterized by morphological changes in the ventricular walls and altered Ca2+ handling of the diseased heart. HCM mutations in troponin cause the cardiac myofilament to become sensitized to Ca2+ which is implicated as causing arrhythmias and sudden cardiac death. In contrast, troponin mutations related to DCM desensitize myofilaments to Ca2+ which often leads to congestive heart failure. CTn mutations related to cardiomyopathy have been extensively studied in the cardiac system. However, the functional consequences of cardiomyopathic C/SSTnC mutants also present in slow skeletal muscle are unknown. The question to be addressed in this grant is: What are the functional consequences of C/SSTnC mutations linked to HCM and DCM in the regulation of slow skeletal muscle contraction? How do they compare to those found in cardiac muscle? To accomplish this, in vitro systems will be utilized as well as skinned fibers which will be used to measure the force/pCa relationship. These measurements will be performed in both skeletal and cardiac muscles. An HCM CTnC knock-in mouse generated in the laboratory will be characterized to determine the in vivo consequences of the mutation in intact and skinned fibers. The aims of this proposal address the functional differences that underlie the phenotypes of C/SSTnC mutations in cardiac and skeletal muscles. These studies will investigate whether slow skeletal muscle containing C/SSTnC mutations develops skeletal abnormalities similar to those seen in the heart and whether the function of skeletal muscle is altered in the mutation-knock in mouse model. The questions that are being addressed are: Is the change that occurs in the skeletal system comparable to changes that occur in cardiac muscle? If the functional changes in slow skeletal muscle appear minimal what additional components absent in the regulation of cardiac muscle assist in rescuing the effects of the mutation? Successful execution of these aims will lead to a better understanding of cardiac versus slow skeletal muscle disorders associated with mutations in the TnC gene.

项目摘要 心肌肌钙蛋白复合物（CTn）由心肌肌钙蛋白T（CTnT）组成，其连接心肌肌钙蛋白T（CTnT）。 与细丝复合;心肌肌钙蛋白I（CTnI），参与抑制肌肉收缩 以及心脏/慢骨骼肌钙蛋白C（CTnC），其结合Ca 2+并触发收缩。一切器皿的银子 CTn调节肌肉收缩，即，力发展的Ca 2+敏感性，最大力 发展和基础力量。心脏/缓慢骨骼肌肌钙蛋白C（C/SSTnC）是 CTn在心肌和慢骨骼肌中表达和存在。它被认为是 横纹肌的主要Ca 2+传感器，并且一直是肥大（HCM）和扩张的目标 (DCM)心肌病。HCM或DCM是由TnC突变引起的遗传性疾病， 以心室壁的形态变化和Ca 2+改变为特征的基因 处理患病的心脏肌钙蛋白HCM突变导致心肌肌丝 对Ca 2+敏感，这与引起心律失常和心脏性猝死有关。与此相反， 与DCM相关的肌钙蛋白突变使肌丝对Ca 2+不敏感，这通常导致充血性心肌病。 心衰与心肌病相关的CTn突变已在心脏 系统然而，心肌病性C/SSTnC突变体的功能后果也 存在于慢骨骼肌中的未知。本补助金要解决的问题是： 是与HCM和DCM相关的C/SSTnC突变在调节 减缓骨骼肌收缩它们与心肌中发现的那些相比如何？到 为了实现这一点，将利用体外系统以及将用于 测量力/pCa关系。这些测量将在骨骼和 心肌在实验室中产生的HCM CTnC敲入小鼠将被表征为 确定在完整的和带皮的纤维中突变的体内后果。其目的是 该提案解决了C/SSTnC突变表型背后的功能差异， 心脏和骨骼肌。这些研究将调查是否缓慢骨骼肌含有 C/SSTnC突变会产生与心脏相似的骨骼异常， 在突变敲除小鼠模型中骨骼肌的功能改变。的问题 正在解决的问题是：骨骼系统中发生的变化是否与 发生在心肌中如果慢速骨骼肌的功能变化很小， 在心肌调节中不存在的另外的组分有助于挽救心肌收缩的作用。 变异？这些目标的成功实现将有助于更好地理解心脏与 与TnC基因突变相关的缓慢骨骼肌疾病。