Mechanisms of selective glycolytic inhibition in ischemic kidney proximal tubles

摘要 缺血性肾损伤（IRI）后，在体内发生选择性近端直小管（PST）损伤 实验模型以前的报道表明，选择性糖酵解抑制和 随之而来的ATP耗竭是引发所有后续事件的起始原因， PST损伤和细胞死亡引起肾功能不全;然而， 糖酵解被抑制没有阐明。我们最近的报告表明，聚（ADP-核糖） 聚合酶-1（PARP-1）介导对关键糖酵解酶甘油醛-3-的抑制 磷酸脱氢酶（GAPDH），可以诱导糖酵解下调和ATP消耗， IRI。然而，PARP-1对GAPDH的抑制作用仅部分解释了ATP耗竭，提示 在另外的糖酵解步骤中可能发生协同抑制。目前的建议是基于 新的初步数据表明，一种新的范式，链接p53靶TIGAR（Tp 53诱导 糖酵解和凋亡调节剂）到限速糖酵解酶的代谢调节 磷酸果糖激酶（PFK）诱导IRI后ATP耗竭和PST损伤。的目的 建议是确定TIGAR调节糖酵解能量的作用和机制 在缺血性肾PST代谢，并确定是否协同抑制TIGAR和PARP- 1保护糖酵解抑制和ATP耗竭的设置IRI。核心假设 是通过TIGAR调节关键糖酵解酶PFK和GAPDH活性， PARP-1分别导致缺血心肌糖酵解和无氧ATP产生的下调， PST。基于我们强有力的初步数据，假设的有效性将通过以下方式进行检验： 以下三个具体目标：1）确定肾组织中TIGAR激活的机制， PSTs抑制IRI后无氧能量产生; 2）确定缺血应激水平是否转换 TIGAR对ROS清除和自噬的响应与糖酵解抑制和细胞死亡 3）确定TIGAR和PARP活化的协同抑制是否完全 在体内模型中保护PST免受缺血/缺氧损伤。圆满完成拟议的 研究，将建立一个新的范式的作用，PARP-1和TIGAR的主要机制 在IRI中启动糖酵解抑制、ATP耗竭和PST损伤。这些研究具有创新性， PARP-1和TIGAR在病理条件下糖酵解抑制中的作用， 缺血/再灌注损伤以前没有在任何器官中得到解决。该研究的结果 可以提供新的治疗机会，干预PARP-1和TIGAR功能，以调节 PST损伤在其发病时，并可能推断干预人类阿基的发病机制。

Abstract Following ischemic renal injury (IRI), selective proximal straight tubule (PST) injury occurs in in vivo experimental models. Previous reports indicated that selective glycolytic inhibition and the consequent ATP depletion is the initiating cause that triggers all the subsequent events leading to PST injury and cell death to instigate renal dysfunction; however, the exact mechanism by which glycolysis is inhibited is not elucidated. Our recent report demonstrates that poly (ADP-ribose) Polymerase-1 (PARP-1) mediated inhibition of the key glycolytic enzyme, glyceraldehyde-3- phosphate dehydrogenase (GAPDH), can induce downregulation of glycolysis and ATP depletion in IRI. However, GAPDH inhibition by PARP-1 only partially accounted for ATP depletion, suggesting that synergetic inhibition at additional glycolytic steps may occur. The current proposal is based on new preliminary data indicating a novel paradigm that links p53 target TIGAR (Tp53 inducible glycolysis and apoptosis regulator) to metabolic regulation of the rate limiting glycolytic enzyme Phosphofructokinase (PFK) to induce ATP depletion and PST injury post-IRI. The objective of the proposal is to define the role and the mechanisms by which TIGAR regulate glycolytic energy metabolism in ischemic renal PST and determine whether synergistic inhibition of TIGAR and PARP- 1 protects from glycolytic inhibition and ATP depletion in the setting of IRI. The central hypothesis is that modulation of the activity of the key glycolytic enzymes, PFK and GAPDH by TIGAR and PARP-1 respectively, leads to downregulation of glycolysis and anaerobic ATP production in ischemic PSTs. Based on our strong preliminary data, the validity of the hypothesis will be tested by pursuing the following three specific aims: 1) determine the mechanism by which TIGAR activation in renal PSTs inhibits anaerobic energy production post-IRI; 2) determine if the level of ischemic stress switch TIGAR response towards ROS scavenging and autophagy versus glycolytic inhibition and cell death pathways post-IRI and 3) determine if synergetic inhibition of TIGAR and PARP activation completely protects PST from ischemic/hypoxic injury in in vivo models. Successful completion of the proposed studies, will establish a new paradigm on the role of PARP-1 and TIGAR as the primary mechanism that initiates glycolytic inhibition, ATP depletion and PST injury in IRI. The studies are innovative as a role for PARP-1 and TIGAR in glycolytic inhibition in a pathological condition such as ischemia/reperfusion injury has not been previously addressed in any organ. Results from the study may provide novel therapeutic opportunities to intervene in PARP-1 and TIGAR functions to modulate PST injury at its onset and may be extrapolated to intervene in the pathogenesis of human AKI.