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 心肌收缩能力是心脏功能所必需的。肌钙蛋白介导的细小肌丝调节 控制心肌收缩和松弛。肌钙蛋白复合体由三个蛋白质亚基组成： 钙受体肌钙蛋白C(TNC)、抑制亚基肌钙蛋白I(TnI)和原肌球蛋白结合亚单位 肌钙蛋白T(TnT)。心脏TnI在肌丝激活和失活中起关键作用，决定了 心肌收缩和松弛的动力学，以及心脏的泵血效率。我们的研究项目 重点介绍了一种源于心脏TnI保守的C末端移动结构域的新的治疗性多肽 (cTnI-C27)研究其增强心肌松弛的作用及其机制。生化的， 采用遗传学和生理学方法以及舒张性心功能障碍的小鼠模型进行研究。 目的了解cTnI-C27多肽对心脏舒缩功能的选择性增强作用。最终目标是 开发一种针对目前缺乏有效治疗方法的舒张性心力衰竭(HFpEF)的靶向治疗方法。 在研究计划中提出了三个具体目标：目标1描述了 外源性cTnI-C27多肽作为激活状态特异性肌丝调节肌丝功能的研究 脱敏剂。我们将确定cTnI-C27肽与细丝和原肌球蛋白的结合位置。 表征其对肌原纤维肌动球蛋白收缩动力学和内源性肌钙蛋白调节的影响 重组肌丝和去皮心肌中的ATPase。结果将决定外生性有多大 CTnI-C27多肽对心肌收缩功能的调节，特别是对Frank-Starling反应的增强 而不增加肌节长度。目的2研究cTnI-C27多肽对心肌细胞的转运作用 功能效应。心脏归巢融合多肽、AAV9及cTnI-C27多肽的诱导转基因表达 将在体内和体外工作心脏中进行研究。对心肌收缩能力和心功能的影响 将检查对正常和舒张期功能障碍和纤维化小鼠心脏的治疗效果 评价cTnI-C27多肽的治疗潜力。目标3是确定外源激素的慢性影响 CTnI-C27多肽对心功能和重构的影响。开发cTnI-C27多肽用于治疗慢性粒细胞白血病 慢性心力衰竭时，需要了解cTnI-C27多肽的慢性存在对心脏的影响 肌肉。我们将研究慢性转基因表达cTnI-C27多肽的疗效和副作用 在正常和衰竭的小鼠心脏中。体内和体外心脏功能，对血流动力学应激的耐受性 将对年轻和老年小鼠的心肌重构进行检查，以收集信息丰富的纵向数据。 拥有肌丝蛋白结构-功能关系和心脏生理学的综合专业知识 利用多水平实验方法，研究一种有希望的治疗性多肽 内生起源将为翻译一种新的肌丝奠定机制和方法论基础 机制转化为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.