Novel roles of PDK2 in heart failure: Regulation of mitochondrial nuclear crosstalk via metabolic regulation and histone acetylation

项目总结/摘要 心血管疾病是世界上主要的死亡原因。心脏代谢的变化 底物利用是心力衰竭发展的基础，并可能在心力衰竭发展中起致病作用。一 调节心脏完全氧化葡萄糖能力的临界点是丙酮酸 脱氢酶（PDH）复合物，在心脏中，由磷酸化介导的负调节 两种PDH激酶（PDK 2和PDK 4）。PDK在响应于生理学的变化中被差异调节。 刺激（例如，运动）和病理刺激（例如，心力衰竭）。因此，它们可能代表 治疗干预的候选人。然而，监管PDK的早期尝试并没有 全面测试了各个亚型。我们实验室的一个长期目标是了解 这些不同的亚型在心力衰竭的进展中的作用。我们使用种系敲除的初步数据 在压力超负荷诱导的心力衰竭模型中， 令人信服的数据对Pdk 2的损失具有保护作用，对Pdk 4的损失具有加重作用。 此外，我们的初步表征鉴定了几种PDK亚型特异性分子， 差异，包括Pdk 2-/-心脏中更高的蛋白质乙酰化和 Pdk 4-/-小鼠。我们还提供了证据，以支持一种机制，通过这种机制，差异乙酰化是 靶向细胞核，并可能在组蛋白密码中发挥作用，将其与表观遗传调控联系起来 的基因表达。确定这些PDK亚型分子机制的关键障碍 就是能够单独检查每一个。为了克服这一障碍，我们 可诱导的心肌细胞特异性敲除，以测试这些激酶在成人中的组织特异性作用 心中本提案的目的是检验PDK 2丢失，但不 PDK 4通过差异表观遗传（组蛋白乙酰化）和 转录调节对压力超负荷诱导的心力衰竭的反应。我们已经开发 两种新的小鼠模型来验证这一假设。在本提案中，我们将： 心力衰竭进展中的PDK亚型（目的1）并确定其分子机制 差异（目标2）。总的来说，这些研究的完成将提供基本的见解， 单个PDK亚型在心脏基因表达调控中的机制基础 导致心力衰竭

PROJECT SUMMARY/ABSTRACT Cardiovascular disease is the leading cause of death in the world. Changes in cardiac metabolic substrate utilization underlie, and may play a causative role in, the development of heart failure. A critical point of regulation in the ability of the heart to fully oxidize glucose is that of the pyruvate dehydrogenase (PDH) complex that, in the heart, is negatively regulated by phosphorylation mediated by two PDH kinases (PDK2 and PDK4). PDKs are differentially regulated in response to physiological stimuli (e.g., exercise) and pathological stimuli (e.g., heart failure). Therefore, they represent likely candidates for therapeutic intervention. However, early attempts to regulate the PDKs have not fully tested the individual isoforms. A long-term goal of our laboratory is to understand the role of these different isoforms in the progression of heart failure. Our preliminary data using germline knockout mice for either of these isoforms in a pressure-overload induced model of heart failure, provides compelling data for a protective role for loss of Pdk2, and an exacerbated role for loss of Pdk4. Furthermore, our initial characterization identified several PDK isoform specific molecular differences, including higher protein acetylation in Pdk2-/- hearts and a higher mortality in Pdk4-/- mice. We also provide evidence to support a mechanism by which the differential acetylation is targeted to the nucleus and may play a role in the histone code, linking it to epigenetic regulation of gene expression. A critical barrier in determining the molecular mechanisms of these PDK isoforms has been the ability to examine each individually. To overcome this barrier, we have generated inducible cardiomyocyte specific knockouts to test the tissue-specific roles of these kinases in adult hearts. The objective of the current proposal is to test the hypothesis that loss of PDK2, but not PDK4, is cardioprotective through differential epigenetic (histone protein acetylation) and transcriptional regulation in response to pressure-overload induced heart failure. We have developed two novel mouse models to test this hypothesis. In this proposal we will: determine the role of each PDK isoform in heart failure progression (Aim 1) and identify molecular mechanisms of these differences (Aim 2). Collectively, the completion of these studies will provide fundamental insights into the mechanistic basis for individual PDK isoforms in the regulation of cardiac gene expression contributing to the development of heart failure.