Troponin Modulation in Heart Failure

描述(申请人提供)：在我们提出的实验中，我们测试了一种假设，即通过p21激活的激酶(Pak1)向蛋白磷酸酶2A(PP2A)发送信号是一种新的机制，通过抑制兴奋收缩偶联(ECC)中的钙释放单位(CRU)来影响钙通道和兰诺定受体功能，并通过肌节蛋白去磷酸化刺激肌丝对钙的反应来控制收缩。本研究期间的初步和已发表的数据表明，pak1在收缩的综合控制中的作用包括通过2-受体/PKA对pak1的磷酸化，以及通过鞘磷脂相关的脂信号也激活了pak1。我们还发现了不同活性形式的PKC6调节肌瘤蛋白磷酸化的新机制，PKC6也作用于与Ak1的信号复合体。我们建议的第一个目的是验证这一假说，即Pak1-PP2A信号通路是一种新的机制，通过调节ECC中CRU活性和肌丝对钙的反应来控制收缩能力。目的#2确定不同的PKC6激活途径导致cTnI和cTnT去磷酸化以及MyBP-C和TM磷酸化的功能意义。目的#3扩展我们关于肌丝对钙离子反应的新调控的研究，以确定肌丝对钙离子的特异性脱敏是否可以作为治疗工具来预防或减轻家族性肥厚性心肌病(HCM)转基因小鼠模型的肥大和功能障碍的发展。我们的初步和已发表的数据表明，肌丝对钙的脱敏反应能够挽救小鼠模型中HCM连锁的肌瘤突变的不良影响。提出的实验结果将提供对一种以前未被认识的收缩激活模式的洞察，这将为心肌病的转化医学提供新的线索。

DESCRIPTION (provided by applicant): In experiments proposed here we test the hypothesis that signaling through p21 activated kinase (Pak1) to protein phosphatase 2A (PP2A) is a novel mechanism of control of contractility by suppression of Ca-release units (CRU) in excitation contraction coupling (ECC) via effects on Ca2+ channel and ryanodine receptor function and stimulation of myofilament response to Ca2+ via sarcomeric protein dephosphorylation. Preliminary and published data in the current period of funding indicate that the function of Pak1 in integrated control of contractility involves signaling through 2-receptor/PKA phosphorylation of Pak1 and through sphingomyelin related lipid signaling that also activates Pak1. We also identified a novel mechanism of regulation of sarcomeric protein phosphorylation by various active forms of PKC6, which also acts in a signaling complex with Pak1. Aim #1 of our proposals is to test the hypothesis that the Pak1-PP2A signaling cascade is a novel mechanism of control of contractility acting by regulating the balance of CRU activity in ECC and myofilament response to Ca2+. Aim #2 is to determine the functional significance of diverse pathways of activation of PKC6 that induce dephosphorylation of cTnI and cTnT and phosphorylation of MyBP- C and Tm. Aim # 3 extends our studies on novel control of myofilament response to Ca2+ to our objective to determine if specific desensitization of the myofilaments to Ca2+ can serve as a therapeutic tool to prevent or attenuate the development of hypertrophy and dysfunction in transgenic mouse models of familial hypertrophic cardiomyopathy (HCM). Our preliminary and published data indicate that desensitization of myofilament response to calcium is able to rescue adverse effects in HCM-linked sarcomeric mutations in mouse models. Results of experiments proposed will provide insights into a previously unappreciated mode of activation of contractility, which provides new leads in translation medicine in cardiomyopathies.