FHC Tn Mutations: Functional Consequences & Mechanisms

FHC Tn 突变：功能性后果

• 批准号: 6619477
• 负责人: JAMES Douglas POTTER
• 金额: $ 37.66万
• 依托单位: UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-25 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6619477
• 关键词: calcium flux; clinical research; disease /disorder model; enzyme activity; enzyme mechanism; gene mutation; genetically modified animals; histopathology; human tissue; hypertrophic myocardiopathy; laboratory mouse; molecular pathology; muscle contraction; muscle proteins; muscle relaxation; myocardium; myosins; protein structure function; sudden cardiac death; troponin

Familial Hypertrophic Cardiomyopathy (FHC) is an autosomal dominant disease, which has been associated with mutations in almost every major cardiac sarcomeric protein. Whereas individuals with myosin heavy chain (MHC) mutations, in general, have a higher level of cardiac hypertrophy, those with cardiac Troponin T (CTnT) and some of the reported Troponin I (CTnI) mutations have less hypertrophy and a higher incidence of sudden cardiac death (SCD). Most recently, a single mutation in Troponin C has been reported to be possibly associated with FHC. Although several mutations have been extensively characterized in vitro, it is still unclear how they cause cardiac hypertrophy or SCD. Our working hypothesis is that FHC troponin mutations alter the pCa-force and -ATPase relationships, the ability of the muscle to develop maximum force and ATPase activity, myosin cross-bridge kinetics, efficiency of contraction, and the ability of the muscle to do work. That mutations, which increase Ca2+- sensitivity, are more closely associated with sudden death, while mutations, which decrease the ability of the muscle to develop force, are more closely associated with hypertrophy. Recently reported transgenic mouse results along with our data from three transgenic mouse lines expressing the human CTnT (HCTnT) FHC mutations (I79N, F1101 and R278C) and HCTnI-R145G, support this hypothesis. The objective of this proposal is to comprehensively study the in vitro consequences (e.g. Ca2+-sensitivity of contraction, kinetics of force development/relaxation, impaired CTnI inhibitory function, etc.) of different FHC associated Troponin mutations in existing and new transgenic mice to identify the key mechanisms involved in the pathogenesis of FHC. This application brings together highly talented scientists at the University of Miami with varied backgrounds and represents a comprehensive approach to the study of these troponin mutations. Our goal is to correlate, the observed effects of mutations in CTnT, CTnI and CTnC on the Ca2+ regulation of cardiac muscle contraction in our animal models, with the pathogenesis of FHC in humans, especially in cases where sudden cardiac deaths have been reported. These studies will determine the functional consequences of different troponin T, troponin I and troponin C mutations under the same experimental conditions, and thus help identify key mechanism(s) involved in the pathogenesis of Troponin-linked FHC and lead to potential therapeutic strategies

家族性肥厚型心肌病 (FHC) 是一种常染色体显性遗传疾病，与几乎所有主要心脏肌节蛋白的突变有关。一般来说，具有肌球蛋白重链 (MHC) 突变的个体心脏肥大程度较高，而具有心肌肌钙蛋白 T (CTnT) 和一些报道的肌钙蛋白 I (CTnI) 突变的个体肥厚程度较低，突发心脏病的发生率较高。心源性死亡（SCD）。 最近，据报道肌钙蛋白 C 的单一突变可能与 FHC 相关。尽管一些突变已在体外得到广泛表征，但仍不清楚它们如何导致心脏肥大或 SCD。 我们的工作假设是，FHC 肌钙蛋白突变改变了 pCa 力和 ATP 酶关系、肌肉产生最大力和 ATP 酶活性的能力、肌球蛋白跨桥动力学、收缩效率以及肌肉做功的能力。 增加 Ca2+- 敏感性的突变与猝死更密切相关，而降低肌肉产生力量的能力的突变与肥大更密切相关。 最近报道的转基因小鼠结果以及我们来自表达人类 CTnT (HCTnT) FHC 突变（I79N、F1101 和 R278C）和 HCTnI-R145G 的三个转基因小鼠品系的数据支持了这一假设。 本提案的目的是全面研究现有和新转基因小鼠中不同 FHC 相关肌钙蛋白突变的体外后果（例如收缩的 Ca2+ 敏感性、力发展/放松的动力学、CTnI 抑制功能受损等），以识别FHC发病机制中涉及的关键机制。该应用程序汇集了迈阿密大学具有不同背景的才华横溢的科学家，代表了研究这些肌钙蛋白突变的综合方法。我们的目标是将动物模型中观察到的 CTnT、CTnI 和 CTnC 突变对心肌收缩 Ca2+ 调节的影响与人类 FHC 的发病机制联系起来，特别是在有心脏性猝死报道的情况下。 这些研究将确定相同实验条件下不同肌钙蛋白 T、肌钙蛋白 I 和肌钙蛋白 C 突变的功能后果，从而有助于确定肌钙蛋白相关 FHC 发病机制中涉及的关键机制，并产生潜在的治疗策略