C-terminal Peptide of Cardiac Troponin I for the Treatment of Diastolic Hear Failure

项目名称：心肌肌钙蛋白I C端肽治疗舒张性心力衰竭 项目摘要 心肌收缩力对心脏功能至关重要。肌钙蛋白介导的细肌丝调节 控制心肌收缩和舒张。肌钙蛋白复合物由三个蛋白质亚基组成： 钙受体肌钙蛋白C（TnC）、抑制性亚单位肌钙蛋白I（TnI）和原肌球蛋白结合亚单位 肌钙蛋白T（TnT）。心肌肌钙蛋白I在肌丝激活和失活中起着关键作用，决定了心肌细胞的功能。 心肌收缩和舒张的动力学以及心脏的泵送效率。我们的研究项目 着重于一种新的治疗肽衍生自保守的C-末端移动的结构域的心脏肌钙蛋白I （cTnI-C27）增强心肌舒张的作用及其机制。生物化学， 采用遗传学和生理学方法以及舒张性心功能不全的小鼠模型来研究 cTnI-C27肽，了解其选择性增强心脏舒张功能。最终目标是 开发针对舒张性心力衰竭（HFpEF）的靶向治疗，目前缺乏有效的治疗方法。 研究计划中提出了三个具体目标：目标1是表征 外源性cTnI-C27肽作为激活状态特异性肌丝Ca 2 +- 脱敏剂我们将确定cTnI-C27肽在细丝中原肌球蛋白上的结合位点， 表征其对肌原纤维肌动球蛋白的收缩动力学和内源性肌钙蛋白调节的作用 重组肌丝和去皮心肌中的ATP酶。结果将决定如何外源 cTnI-C27肽调节心肌收缩力，尤其是增强Frank-Starling反应 而不增加肌节长度。目的2：研究cTnI-C27肽在心肌细胞内的转运， 功能效应心脏归巢融合肽、AAV 9及cTnI-C27肽的诱导性转基因表达 将在体内和离体工作心脏中进行研究。对心肌收缩力和心脏功能的影响 将检查在正常和舒张功能障碍和纤维化小鼠心脏中的治疗功效， 评价cTnI-C27肽的治疗潜力。目的3是确定外源性的慢性效应 cTnI-C27肽对心脏功能和重塑的影响。开发cTnI-C27肽用于治疗 慢性心力衰竭，我们需要了解肌钙蛋白I-C27肽长期存在对心脏的影响 肌肉.我们将研究慢性转基因表达cTnI-C27肽的治疗和副作用 在正常和衰竭的小鼠心脏中。体内和离体心脏功能、对血流动力学应激的耐受性，以及 将在年轻和年老小鼠中检查心肌重塑以收集信息性纵向数据。 结合肌丝蛋白质结构-功能关系和心脏生理学方面的专业知识， 病理生理学，采用多层次的实验方法，一个有前途的治疗肽的研究， 内源性起源将为翻译新的肌丝奠定机制和方法学基础 这是一种治疗舒张性心力衰竭的新方法。

Project Title: C-terminal Peptide of Cardiac Troponin I for the Treatment of Diastolic Heart Failure Project Summary Myocardial contractility is essential for cardiac function. Troponin-mediated thin myofilament regulation controls cardiac muscle contraction and relaxation. The troponin complex consists of three protein subunits: the calcium receptor troponin C (TnC), the inhibitory subunit troponin I (TnI), and the tropomyosin-binding subunit troponin T (TnT). Cardiac TnI plays a pivotal role in myofilament activation and deactivation, determining the kinetics of cardiac muscle contraction and relaxation, and pumping efficiency of the heart. Our research project focuses on a novel therapeutic peptide derived from the conserved C-terminal end mobile domain of cardiac TnI (cTnI-C27) for its effect on enhancing myocardial relaxation and the underlying mechanisms. Biochemical, genetic and physiological approaches and mouse models of diastolic cardiac dysfunction are employed to study cTnI-C27 peptide to understand its selective enhancement of diastolic function of the heart. The ultimate goal is to develop a targeted treatment for diastolic heart failure (HFpEF) that presently lacks an effective treatment. Three Specific Aims are proposed in the research plan: Aim 1 is to characterize the mechanism for exogenous cTnI-C27 peptide to modulate myofilament function as an activated state-specific myofilament Ca2+- desensitizer. We shall determine the binding site of cTnI-C27 peptide on tropomyosin in thin filament and characterize its effect on contractile kinetics and endogenous troponin regulation of myofibril actomyosin ATPase in reconstituted myofilaments and skinned cardiac muscle. The results will determine how exogenous cTnI-C27 peptide modulates cardiac muscle contractility, especially the enhanceing of Frank-Starling response without increasing sarcomere length. Aim 2 is to study the delivery of cTnI-C27 peptide into cardiomyocytes for functional effect. Heart-homing fusion peptide, AAV9 and inducible transgenic expression of cTnI-C27 peptide will be studied in vivo and in ex vivo working hearts. Effects on cardiac muscle contractility and heart function will be examined for therapeutic efficacy in normal and diastolic dysfunctional and fibrotic mouse hearts to evaluate the therapeutic potential of cTnI-C27 peptide. Aim 3 is to determine the chronic effects of exogenous cTnI-C27 peptide on cardiac function and remodeling. To develop the cTnI-C27 peptide for the treatment of chronic heart failure, we need to understand the effects of chronic presence of cTnI-C27 peptide on cardiac muscle. We shall examine the therapeutic and side-effects of chronic transgenic expression of cTnI-C27 peptide in normal and failing mouse heart. In vivo and ex vivo cardiac function, tolerance to hemodynamic stresses, and myocardial remodeling will be examined in young and aging mice to collect informative longitudinal data. With combined expertise in myofilament protein structure-function relationships and cardiac physiology and pathophysiology using multi-level experimental approaches, the study of a promising therapeutic peptide of endogenous origin will lay mechanistic and methodologic groundwork for translating a novel myofilament mechanism into a new treatment for diastolic heart failure.