SIRT1, Nitro-Lipids and Cardioprotection

描述(申请人提供)：心脏缺血-再灌注(IR)损伤是导致心脏病发作(急性心肌梗死)的病理过程。尽管进行了几十年的研究，但心脏保护疗法很少，在美国，每年有22万人死于急性心肌梗死。此外，每年有38万名患者。在心脏手术期间经历可预见的缺血。这项正在进行的计划的总体目标是为IR损伤开发新的心脏保护疗法。这是一个竞争性的续签申请，在前一个资助周期中，我们发表了19篇直接归因于该奖项的主要研究文章(以及17篇额外的论文)。在此期间，我们确定了在急性缺血预适应(IPC)的内源性心脏保护现象中的两个关键信号转导分子。首先，我们证明了在IPC中不产生衍生的硝基脂质，并共价加合线粒体腺嘌呤核苷酸转位酶1(ANT1)。这会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损伤的机制。其次，我们证明了赖氨酸脱乙酰酶SIRT1是急性心脏保护信号所必需的，并且SIRT1转基因小鼠对IR损伤具有内源性保护作用。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，硝基类脂共价修饰SIRT1，这表明硝基类脂和SIRT1信号之间存在串扰。硝基脂质和SIRT1介导心脏保护的下游机制尚不清楚，但我们的初步数据表明代谢变化和刺激有丝分裂的重要性，这两者都与心脏保护有关。此外，我们还开发了一个适用于成人原代心肌细胞的基于细胞的筛选平台，使我们能够在体内发现能够启动这些机制来保护心脏免受IR损伤的小分子。总体而言，这些观察结果导致了一个中心假设，即硝化脂和SIRT1共同作用于保护 通过代谢和有丝分裂的改变来保护心脏免受IR损伤。在这个项目中，我们将利用这些内源性保护途径，通过输送在缺血前和再灌注时调节它们的小分子来达到治疗的目的。最终目标是为临床前开发提供新的心脏保护分子。为了实现这一目标并验证我们的假设，我们将追求以下三个具体目标：目标1将确定硝基脂质作用的心脏保护靶点，重点是ANT1和有丝分裂吞噬。目的2将研究SIRT1的心脏保护靶点，重点是新陈代谢。AIM 3将开发筛选热门，重点放在影响有丝分裂和新陈代谢的分子上。解决这些目标将产生一系列作为心脏保护疗法的临床前开发的小分子候选药物，并将增强我们对心脏保护的潜在机制的理解。

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.