Troponin Modulation in Heart Failure

描述（由申请人提供）：在这里提出的实验中，我们测试了p21活化激酶（Pak1）到蛋白磷酸酶2A （PP2A）的信号传导是一种控制收缩性的新机制，它通过影响Ca2+通道和ryanodine受体功能来抑制兴奋收缩偶联（ECC）中的ca释放单元（CRU），并通过肌聚蛋白去磷酸化刺激肌丝对Ca2+的反应。在当前资助期内的初步和已发表的数据表明，Pak1在综合控制收缩性中的功能涉及通过2受体/PKA磷酸化Pak1和通过鞘磷脂相关的脂质信号传导，也激活Pak1。我们还发现了一种新的机制，通过PKC6的各种活性形式调节肌肉蛋白磷酸化，PKC6也在与Pak1的信号复合体中起作用。我们建议的目的1是验证Pak1-PP2A信号级联是通过调节ECC中CRU活性的平衡和肌丝对Ca2+的反应来控制收缩性的新机制的假设。目的2是确定PKC6激活的不同途径的功能意义，这些途径诱导cTnI和cTnT的去磷酸化以及MyBP- C和Tm的磷酸化。Aim # 3将我们对肌丝对Ca2+反应的新控制的研究扩展到我们的目标，以确定肌丝对Ca2+的特异性脱敏是否可以作为一种治疗工具，以预防或减轻家族性肥厚性心肌病（HCM）转基因小鼠模型中肥厚和功能障碍的发展。我们的初步和已发表的数据表明，在小鼠模型中，肌丝对钙的脱敏反应能够挽救hcm相关肉瘤突变的不良反应。提出的实验结果将为以前未被重视的收缩性激活模式提供见解，这为心肌病的翻译医学提供了新的线索。

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.