Post-translational Modification in Cardiac Muscle

原肌球蛋白（Tm）通过磷酸化和硝化两种翻译后修饰进行修饰。到目前为止，Tm磷酸化和硝化的功能意义还没有很好地理解。这是该建议的目标，以确定Tm磷酸化和硝化的影响，其与肌节蛋白的相互作用和激活的肌节细丝。最近的数据表明，Tm的翻译后修饰可能受到调控，因此，我们进一步建议研究心脏应激对Tm翻译后修饰水平的影响，作为一种新的信号机制，改变心脏肌节收缩。本申请包含调查这些问题的三个具体目标。1)心脏应激是否改变Tm的翻译后修饰以影响收缩功能？2)翻译后修饰的Tm磷酸化或硝化改变其相互作用的细丝蛋白质网络？3)翻译后修改Tm改变Ca2+激活的细丝？ 这些目标将通过研究Tm的影响来实现，Tm已经被以下任一项修饰： 磷酸化或硝化对Tm与其他肌节细丝蛋白的结合亲和力、Ca 2+的结合和重构细丝的ATP酶活性的影响。我们还建议通过缺血再灌注处理心肌细胞，然后通过鉴定Tm磷酸化和硝化水平来研究心脏应激对Tm翻译后修饰的影响。我们将研究的意义，Tm磷酸化，通过研究钙调节力的发展，在心脏纤维从转基因小鼠过表达假磷酸化Tm。这些研究将提供一个非常需要的分子理解的Tm的功能，以影响心肌收缩的肌节水平和它的作用，作为一种新的信号机制，影响心肌收缩缺血再灌注后的后acetitonal修改。这些研究结果对了解心肌梗死患者心功能不全的分子基础有直接意义。这些研究也将为潜在的药物治疗提供新的见解，以改善心肌梗死和疾病的心功能。

Tropomyosin (Tm) is modified by both posphorylation and nitration post-translational modifications. To date tiie functional significance of Tm pfiospliorylation and nitration are not well understood. It is the goal of this proposal to identify the effect of Tm phosphorylation and nitration on its interactions with the sarcomeric proteins and on activation of the sarcomeric thin filament. Recent data has suggested the post-transiational modification of Tm may be regulated, therefore we further propose to investigate the effect of cardiac stress on the level of Tm post-translational modifications as a novel signaling mechanism to alter cardiac sarcomeric contraction. This application contains three specific aims to investigate these questions. 1) Does cardiac stress alter the post-tranlational modification of Tm to affect contractile function? 2) Does the posttranslational modification of Tm by phsophorylation or nitration alter its interactions within the thin filament protein network? 3) Do post-transiational modifications of Tm alter Ca2+ activation of the thin filament? These aims wiil be carried out by investigating the effect of Tm that has been modified by either phosphorylation or nitration on Tm binding affinity to the other sarcomeric thin filament proteins, the binding of Ca2+ and the ATPase activity of reconstituted thin filaments. We also propose to investigate the effect of cardiac stress on Tm post-translational modifications by treating cardiac myocytes with ischemic reperfusion followed by identification of Tm phosphorylation and nitration levels. We will investigate the significance of Tm phosphorylation by investigating calcium regulated force development in cardiac fibers from transgenic mice overexpressing pseudo-phosphorylated Tm. These studies will provide a much needed molecular understanding of how the post-translaitonal modification of Tm functions to affect cardiac contraction at the sarcomeric level and its role as a novel signaling mechanism to affect cardiac contraction in ischemic reperfusion. The findings from these studies are direclty relevant to understanding the molecular basis of cardiac dysfunction in human myocardial infarction. These studies wiil also provide new insight into potential pharmacotheriputic treatments to improve heart function in both myocardial infarction and disease.