L-2-Hydroxyglutarate and Metabolic Remodeling in Hypoxia

项目摘要。对低氧的适应性代谢反应反映了基本的进化生存 在所有真核生物中的策略。我们最近发现了一种独特的代谢物，它会增加心血管疾病的发病率 (CV)细胞对缺氧的反应，L-2-羟基戊二酸(L2HG)。这种代谢物来源于α- 酮戊二酸，或2-氧戊二酸(2OG)，三元酸循环中的关键中间体。一旦形成 从2OG和NADH开始，L2HG没有其他的代谢命运，只有经历氧化回到20G 立体特异性脱氢酶，L2HG脱氢酶(L2HGDH)，表明它适应 (‘缓冲液’)伴随低氧而增加的还原当量。L2HG还有另外两个独特的 作用：它抑制糖酵解，如我们这里所示，它增加磷酸戊糖途径(PPP) 活动。这一提议的中心假设是L2HG抑制糖酵解并增强PPP CV细胞中清除活性氧物种(ROS)，维持细胞氧化还原电位，并保存 细胞在低氧条件下的功能。为了解决这一假设，我们将重点关注三个具体目标。首先，我们将 确定L2HG影响糖酵解和PPP的分子代谢机制 活动。特别是，我们将重点关注特定的磷酸果糖激酶-2亚型的独特作用， 在低氧条件下，PFKFB4作为通过PPP增加通量的关键调控决定因素。第二，我们将 确定低氧条件下L2HG诱导的PPP活性增加对细胞氧化还原电位的影响 胞内和胞外ROS清除。在这里，我们将重点介绍PPP衍生的NADPH和GSH AS NADPH氧化酶和谷胱甘肽过氧化物酶活性中的关键辅因子分别为 消除过多的ROS。第三，我们将研究L2HG在缺氧或缺血时对细胞和 分别使用独特的细胞和遗传小鼠模型研究心脏功能。这些加在一起， 研究应提供对L2HG促进代谢重塑的机制的见解 在缺氧状态下保护细胞和心脏功能。

Project Summary. Adaptive metabolic responses to hypoxia reflect essential evolutionary survival strategies in all eukaryotes. We recently identified a unique metabolite that increases in cardiovascular (CV) cells in response to hypoxia, L-2-hydroxyglutarate (L2HG). This metabolite is derived from α- ketoglutarate, or 2-oxoglutarate (2OG), a key intermediate in the tricarboxylic acid cycle. Once formed from 2OG and NADH, L2HG has no other metabolic fate except to undergo oxidation back to 2OG by the stereospecific dehydrogenase, L2HG dehydrogenase (L2HGDH), suggesting that it accommodates (‘buffers’) the increase in reducing equivalents accompanying hypoxia. L2HG has two other unique actions: it suppresses glycolysis and, as we show here, it increases pentose phosphate pathway (PPP) activity. The central hypothesis of this proposal is that L2HG suppresses glycolysis and enhances PPP activity in CV cells to eliminate reactive oxygen species (ROS), maintain cell redox potential, and preserve cell function in hypoxia. To address this hypothesis, we will focus on three specific aims. First, we will determine the molecular metabolic mechanisms underlying the effects of L2HG on glycolysis and PPP activity. In particular, we will focus on the unique role of a specific phosphofructokinase-2 isoform, PFKFB4, as a key regulatory determinant of increased flux through the PPP in hypoxia. Second, we will determine the effect of this L2HG-induced increased PPP activity in hypoxia on cellular redox potential and intra- and extracellular ROS elimination. Here, we will focus on PPP-derived NADPH and GSH as key cofactors in NADPH oxidase and glutathione peroxidase activities, respectively, in order to enhance elimination of excess ROS. Third, we will study the effects of L2HG in hypoxia or ischemia on cellular and cardiac function, respectively, using unique cellular and genetic murine models. Taken together, these studies should provide insights into the mechanisms by which L2HG promotes metabolic remodeling to preserve cell and cardiac function in oxygen-limited states.