Molecular Physiology of Myocardial Troponin I Variants

描述（由申请人提供）：心肌收缩是通过肌丝蛋白对细胞内钙浓度增加的反应而调节的相互作用发生的。在心力衰竭中，钙动力学和肌丝对钙的反应都发生了改变。这些改变损害了收缩和舒张功能，并且可能是可逆的。该建议旨在确定关键调节蛋白肌钙蛋白I变异对心力衰竭和肥厚的影响的具体机制。该建议的假设是，翻译后或遗传变异心肌肌钙蛋白I改变其功能，并在心力衰竭和心率增加和后负荷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功能的潜在分子机制，以便设计预防或治疗心功能障碍的策略。肌钙蛋白I变异的分子病理生理学解剖将在一系列高度协作的综合研究中进行，重点是在小鼠模型和人类心肌细胞中对肌丝疾病相关的翻译后或遗传变异进行建模。为实现这些目标，提出了以下目标：通过定量心肌细胞磷酸化蛋白组学和重组肌钙蛋白I磷酸化位点突变体的表达，确定肌钙蛋白I位点特异性磷酸化改变在人心衰中的程度和影响2。为了确定肌钙蛋白I或磷蛋白PKA位点的磷酸化是否是体内频率依赖性弛豫加速（FDAR）和后负荷弛豫反应的主要因素，使用杂交小鼠模型和3。通过使用体内小鼠模型，验证肌钙蛋白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。这项工作应该提供深入了解特定肌丝肌钙蛋白I变异的体内影响，这有助于心力衰竭和肥厚的病理生理。从长远来看，这将有助于开发新的治疗方法来纠正肌丝缺陷。公共卫生相关性：心力衰竭在美国是一个重要的医学问题。该提案将研究肌钙蛋白I，一种调节心脏收缩的蛋白质。具体目标是研究该蛋白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.