The Role of Tropomyosin Post-translational Modification in Cardiac Muscle

描述（由申请人提供）： 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得到很好的理解。这是该建议的目标，以确定Tm磷酸化和硝化的影响，其与肌节蛋白质的相互作用和激活的肌节细丝。最近的数据表明，Tm的翻译后修饰可能是受调控的，因此，我们进一步提出研究心脏应激对Tm翻译后修饰水平的影响，作为一种新的信号机制，以改变心脏肌节收缩。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)Tm的翻译后修饰是否改变了细丝的Ca 2+激活？这些目标将通过研究已经通过磷酸化或硝化修饰的Tm对其他肌节细丝蛋白的Tm结合亲和力、Ca2+与重构细丝的结合以及重构细丝的ATP酶活性的影响来实现。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。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。这些研究结果直接关系到了解人类心肌梗死心功能不全的分子基础。这些研究还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脏功能。

DESCRIPTION (provided by applicant): Tropomyosin (Tm) is modified by both posphorylation and nitration post-translational modifications. To date the functional significance of Tm phosphorylation 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 sarcomere proteins and on activation of the sarcomere thin filament. Recent data has suggested the post-translational 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-translational modifications of Tm alter Ca2+ activation of the thin filament? These aims will 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+ to reconstituted thin filaments 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. 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 directly relevant to understanding the molecular basis of cardiac dysfunction in human myocardial infarction. These studies will also provide new insight into potential pharmacotheriputic treatments to improve heart function in both myocardial infarction and disease.