Role of protein S-nitrosation in cardioprotection

描述(申请人提供)：本建议的目的是阐明S-亚硝化(SNO)保护心肌免受缺血-再灌注损伤的机制。S亚硝化是最近发现的一种蛋白质修饰方法，在这种修饰中，一氧化氮部分共价连接到半胱氨酸残基的硫醇上，形成S亚硝硫醇。SNO是一种可逆的修饰，已被证明可以改变靶蛋白的活性。此外，据报道，SNO可以保护硫醇基团免受氧化损伤。心肌细胞内源性产生一氧化氮的潜在来源包括一氧化氮合酶和非酶途径。冠状动脉的短暂闭塞通常会导致心脏缺血-再灌注损伤。这种类型的损伤可能导致心功能障碍，这种功能最初是可逆的(心肌顿抑)，后来是不可逆转的(梗塞)，以及室性心律失常。然而，心脏保护作用源于缺血预适应，这是心脏的一种保护机制，由几次短暂的缺血发作发展而来。据报道，这种心脏保护措施可以增加心肌细胞中S亚硝化的形成。此外，来自女性的心脏表现出内源性心脏保护，这已被证明是一氧化氮合酶依赖的。然而，研究还没有完全表征SNO形成所必需的信号通路或SNO形成发挥心脏保护作用的机制(S)。因此，需要进一步研究S-亚硝化在心脏保护中的作用。S亚硝化的作用将在本提案的具体目标中讨论，具体如下：1)确定在心脏保护中S亚硝化形成所需的特定信号通路，2)确定心脏保护过程中SNO的特定半胱氨酸残基，以及3)确定S亚硝化是否通过保护关键的硫醇基团免受氧化损伤而起到心脏保护作用。这项提议的总体假设如下：1)SNO的形成和心脏保护是在激活特定的信号通路后启动的，2.SNO发生在关键靶蛋白上特定的半胱氨酸残基上，以及3.SNO通过阻断氧化损伤来提供心脏保护。公共卫生相关性：拟议研究的具体目标将确定S亚硝化在心脏保护中的作用，并解决S亚硝化保护缺血再灌注损伤的机制。这些结果也将有助于澄清文献中关于一氧化氮合酶在心脏保护中的作用的疑虑。此外，这些结果可能会通过确定治疗干预的新靶点来改善人类心脏病患者的治疗。

DESCRIPTION (provided by applicant): The purpose of this proposal is to elucidate the mechanism whereby S-nitrosation (SNO) confers cardioprotection from ischemia-reperfusion injury. S-nitrosation is a recently described protein modification in which a nitric oxide moiety is covalently attached to a thiol group of a cysteine residue, leading to the formation of S-nitrosothiols. SNO is a reversible modification that has been shown to modify the activity of target proteins. Additionally, SNO has been reported to protect thiol groups from oxidative damage. Potential sources for the endogenous production of nitric oxide in cardiac myocytes include nitric oxide synthase and non-enzymatic means. Brief occlusion of a coronary artery generally results in cardiac ischemia-reperfusion injury. This type of injury can lead to cardiac dysfunction, which is initially reversible (myocardial stunning) and later irreversible (infarction), and ventricular arrhythmias. However, cardioprotective effects result from ischemic preconditioning, a protective mechanism of the heart that develops from several brief episodes of ischemia. This cardioprotective measure has been reported to increase S-nitrosation formation in the cardiac myocyte. Furthermore, hearts from females exhibit endogenous cardioprotection, which has been shown to be NOS-dependent. However, studies have yet to fully characterize the signaling pathways necessary for SNO formation or the mechanism(s) through which SNO formation exerts cardioprotection. Therefore, further studies are needed in order to examine the role of S-nitrosation in cardioprotection. The role of S-nitrosation will be addressed in the specific aims of this proposal and are as follows: 1) determine the specific signaling pathways that are necessary for S-nitrosation formation in cardioprotection, 2) identify the specific cysteine residues that are SNO during cardioprotection, and 3) determine if S-nitrosation exerts cardioprotective effects by shielding critical thiol groups from oxidative damage. The overall hypotheses of this proposal are as follows: 1.) SNO formation and cardioprotection is initiated upon activation of specific signaling pathways, 2.) SNO occurs at specific cysteine residues on key target proteins, and 3.) SNO provides cardioprotection by blocking against oxidative damage. PUBLIC HEALTH RELEVANCE: The specific aims of the proposed study will determine the role of S-nitrosation in cardioprotection and resolve the mechanism through which S- nitrosation serves to protect against ischemia-reperfusion injury. These results will also help to clarify inconsisties in the literature that relate to the role of nitric oxide synthase in cardioprotection. Additionally, these results may allow for improvements in the treatment of human cardiac patients by identifying novel targets for therapeutic intervention.