FHC Tn Mutations: Functional Consequences & Mechanisms

FHC Tn 突变：功能性后果

• 批准号: 6545025
• 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/6545025
• 关键词: calcium flux; disease /disorder model; enzyme activity; enzyme mechanism; 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

家族性肥厚性心肌病（FHC）是一种常染色体显性疾病，几乎与每种主要的心脏肉瘤蛋白的突变有关。尽管肌球蛋白重链（MHC）突变的个体通常具有较高的心脏肥大水平，但患有心脏肌钙蛋白T（CTNT）的个体和一些报告的肌钙蛋白I（CTNI）突变的肥大质量较小，心脏突然死亡（SCD）的发生率较高。 最近，据报道，肌钙蛋白C中的单个突变可能与FHC有关。尽管几个突变在体外得到了广泛的特征，但仍不清楚它们如何引起心脏肥大或SCD。 我们的工作假设是，FHC肌钙蛋白突变改变了PCA力和-ATPase关系，肌肉发展最大力量和ATPase活性的能力，肌球蛋白跨桥动力学，收缩效率以及肌肉的工作能力。 增加Ca2+ - 灵敏度的突变与猝死更加紧密相关，而突变则降低了肌肉发展力的能力，与肥大更加紧密相关。 最近报道了转基因小鼠的结果以及我们来自表达人CTNT（HCTNT）FHC突变（I79N，F1101和R278C）和HCTNI-R145G的三种转基因小鼠系的数据，支持这一假设。 该提案的目的是全面研究不同FHC相关的肌钙蛋白突变，在现有和新的转基因小鼠中鉴定出涉及FHC常规的关键机制中的不同FHC相关肌钙蛋白突变的体外后果，力发育/松弛的动力学，CTNI抑制功能受损等）。该应用程序汇集了迈阿密大学的高度才华横溢的科学家，背景各异，代表了对这些肌钙蛋白突变的研究的全面方法。我们的目标是将CTNT，CTNI和CTNC突变对我们动物模型中心脏肌肉收缩的Ca2+调控的观察到的影响与人类FHC的发病机理，尤其是在报告心脏突然死亡的情况下。 这些研究将确定在相同的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，从而有助于确定与肌蛋白连接FHC发病机理有关的关键机制，并导致潜在的治疗策略