SIRT1, Nitro-Lipids and Cardioprotection

描述（由申请人提供）：心脏缺血再灌注（IR）损伤是心脏病发作（急性心肌梗死，AMI）的病理过程。尽管经过了几十年的研究，但保护心脏的治疗方法仍然很少，在美国，AMI每年导致1222万人死亡。此外，每年还会有380,000名患者。在心脏手术中进行可预测的缺血。这个正在进行的项目的总体目标是为IR损伤开发新的心脏保护疗法。这是一个竞争性的续期申请，在上一个资助周期中，我们发表了19篇直接归因于该奖项的主要研究论文（以及17篇额外的论文）。在此期间，我们确定了内源性急性缺血预处理（IPC）心脏保护现象中的两个关键信号参与者。首先，我们发现NO衍生的硝基脂质在IPC中产生，并共价加合线粒体腺嘌呤核苷酸转位酶1 （ANT1）。这导致线粒体氧化磷酸化轻度解偶联，这是独立已知的保护IR损伤。其次，我们发现赖氨酸去乙酰化酶SIRT1在急性心脏保护信号传导中是必需的，并且SIRT1转基因小鼠对IR损伤具有内源性保护。虽然这些机制最初可能看起来不同，但我们的初步数据显示，硝基脂质共价修饰SIRT1，表明硝基脂质和SIRT1信号之间存在交叉对话。通过硝基脂质和SIRT1介导心脏保护的下游机制尚不明确，但我们的初步数据表明代谢改变和线粒体自噬刺激的重要性，这两者都与心脏保护有关。此外，我们已经开发了一种适用于成人初级心肌细胞的基于细胞的筛选平台，从而发现可以参与这些机制的小分子，以保护心脏免受体内IR损伤。总的来说，这些观察结果导致了硝基脂质和SIRT1协同起保护作用的中心假设

DESCRIPTION (provided by applicant): Cardiac ischemia-reperfusion (IR) injury is the pathologic process underlying heart-attack (acute myocardial infarction, AMI). Despite decades of research, cardioprotective therapies are scant, and AMI kills >220,000 people annually in the US. In addition, >380,000 patients/yr. undergo predictable ischemia during cardiac surgery. The overall goal of this ongoing program is to develop new cardioprotective therapies for IR injury. This is a competing renewal application, and in the previous funding cycle we published 19 primary research articles directly attributable to this award (and 17 additional papers). During this time we identified two key signaling players in the endogenous cardioprotective phenomenon of acute ischemic preconditioning (IPC). First, we showed NO derived nitro-lipids is generated in IPC, and covalently adducts mitochondrial adenine nucleotide translocase 1 (ANT1). This causes mild uncoupling of mitochondrial oxidative phosphorylation, which is independently known to protect against IR injury. Second, we showed that the lysine deacetylase SIRT1 is necessary for acute cardioprotective signaling, and that SIRT1 transgenic mice are endogenously protected against IR injury. While these mechanisms may initially appear distinct, our preliminary data show that nitro-lipids covalently modify SIRT1, suggesting cross-talk between nitro-lipid & SIRT1 signaling. The downstream mechanisms which mediate cardioprotection by nitro-lipids and SIRT1 are poorly defined, but our preliminary data suggest the importance of alterations in metabolism and the stimulation of mitophagy, both of which are implicated in cardioprotection. Furthermore, we have developed a cell-based screening platform applicable to adult primary cardiomycytes, enabling discovery of small molecules which can engage these mechanisms to protect the heart from IR injury in-vivo. Overall, these observations have led to the central hypothesis that nitro-lipids & SIRT1 act in concert to protect the heart from IR injury via alterations in metabolism and mitophagy. In this project, we will exploit these endogenous protective pathways for therapeutic benefit, by delivering small molecules that modulate them both prior to ischemia AND at reperfusion. The end goal is to deliver novel cardioprotective molecules for pre-clinical development. To achieve this goal and test our hypothesis, we will pursue three following specific aims: Aim 1 will identify cardioprotective targets of nitro-lipid action, with a focus on ANT1 and mitophagy. Aim 2 will investigate cardioprotective targets of SIRT1, with a focus on metabolism. Aim 3 will develop screening hits, with a focus on molecules that impact mitophagy and metabolism. Addressing these aims will yield a series of small molecule candidates for pre-clinical development as cardioprotective therapeutics, and will enhance our understanding of the underlying mechanisms of cardioprotection.