Molecular Physiology of Myocardial Troponin I Variants

描述（由申请人提供）：心脏收缩是通过肌丝蛋白的调节相互作用发生的，以响应细胞内钙浓度的增加。在心力衰竭中，钙动力学和肌丝对钙的反应都改变。这些改变损害收缩和舒张功能，并且可能是可逆的。该提案旨在确定导致心力衰竭和肥大的关键调节蛋白肌钙蛋白I的变体的作用的具体机制。该建议的假设是，翻译后或遗传变异心肌肌钙蛋白I修改其功能，并在心力衰竭和心率和后负荷增加的反应中发挥核心作用。这项工作的长期目标是了解这些变异改变心脏功能的潜在分子机制，以设计预防或治疗心功能障碍的策略。肌钙蛋白I变异体的分子病理生理学的解剖将在一系列高度合作的综合研究中进行，这些研究集中在鼠模型和人心肌细胞中体内肌丝疾病相关的翻译后或遗传变异体变化的建模。为了实现这些目标，提出了以下目标：1。通过人心肌细胞中的定量磷酸化蛋白质组学和人心肌细胞中肌钙蛋白I重组磷酸化位点突变体的表达，确定心力衰竭中肌钙蛋白I位点特异性磷酸化改变的程度和影响2。为了确定是否肌钙蛋白I或受磷蛋白的PKA位点的磷酸化是体内频率依赖性松弛加速（FDAR）和使用杂交小鼠模型对后负荷的松弛反应的主要贡献者和3。通过使用体内小鼠模型，阐明肌钙蛋白I外显子5序列变异（在非裔美国人中发生率为3%）影响急性和慢性后负荷反应的假设。这项工作应提供深入了解在体内的影响，具体肌丝肌钙蛋白I的变体，有助于心脏衰竭和肥大的病理生理。从长远来看，这将有助于开发新的治疗方法，解决肌丝缺陷的纠正。公共卫生相关性：心力衰竭在美国是一个重要的医疗问题。这项提案将研究肌钙蛋白I，一种调节心脏收缩的蛋白质。具体目标是研究这种蛋白质的遗传和蛋白质修饰对心脏功能的影响。从长远来看，这将有助于开发更好的心力衰竭治疗方法。

DESCRIPTION (provided by applicant): Contraction of the heart occurs through regulated interactions of the myofilament proteins in response to increasing intracellular calcium concentrations. In heart failure both calcium dynamics and the response of the myofilaments to calcium are altered. These alterations impair systolic and diastolic function and are potentially reversible. This proposal seeks to define specific mechanisms for the effects of variants of the key regulatory protein troponin I which contribute to heart failure and hypertrophy. The hypothesis of this proposal is that post translational or genetic variants cardiac troponin I modify its function and play a central role in heart failure and the response to increased heart rate and afterload. The long-range goal of this work is to understand the underlying molecular mechanism by which these variants alter cardiac function in order to design strategies to prevent or treat cardiac dysfunction. The dissection of the molecular pathophysiology of troponin I variants will be approached in a series of highly collaborative integrative studies focused on modeling of myofilament disease-related post translational or genetic variants changes in vivo in murine models and in human cardiomyocytes. To address these goals the following aims are proposed: 1. To determine the degree and impact of altered site-specific phosphorylation of troponin I in human heart failure by quantitative phosphoproteomics in human cardiomyocytes and expression of recombinant phosphorylation site mutants of troponin I in human cardiomyocytes 2. To determine whether phosphorylation of PKA sites of troponin I or phospholamban are the dominant contributor to the in vivo frequency dependent acceleration of relaxation (FDAR) and the relaxation response to afterload by use of interbred mouse models and 3. To address the hypothesis that an exon 5 sequence variant of troponin I, which occurs with a 3 % frequency in African-Americans, influences the response to acute and chronic afterload through the use of an in vivo murine model. This work should provide insight into the in vivo effects of specific myofilament troponin I variants which contribute to pathophysiology of heart failure and hypertrophy. In the long-term this will assist in the development of novel therapies which address the correction of myofilament defects. PUBLIC HEALTH RELEVANCE: Heart failure is a significant medical problem in the United States. This proposal will study troponin I, a protein which regulates contraction of the heart. The specific goals are to study the effect of genetic and protein modifications of this protein on heart function. In the long term this should assist in developing better treatments for heart failure.