Mechanisms of PARP and PARG mediated cell death

描述（由申请人提供）：本申请的总体目的是 为了阐明导致PARP和PARG激活的生化事件， 细胞死亡，并研究可能消除这种情况的潜在干预措施 细胞死亡聚（ADP-核糖）聚合酶-1（PARP 1）产生ADP-核糖 当被单链DNA断裂激活时，许多靶蛋白上的聚合物。 PARP 1现在已经被公认为在一定条件下细胞死亡的介质。 导致广泛或持续的激活。特别地，PARP 1基因 干扰和PARP抑制剂已被证明可以减少脑梗死后， 脑缺血然而，PARP之间的干预生化步骤 活化和细胞死亡还没有被很好地理解。我们的初步结果和 以前发表的报告表明，参与二次氧化 应激和受损底物向作为关键中间体的线粒体的递送 PARP 1介导的细胞死亡的步骤。为细胞提供抗氧化剂或 在PARP 1活化后的时间点的TCA循环底物改善了细胞 生存聚（ADP-核糖）糖水解酶（PARG）结合（ADP-核糖） PARP 1产生的聚合物，并迅速将其水解为单（ADP-核糖）。我们 初步结果还表明，PARG与PARP 1在 介导氧化和兴奋性毒性细胞死亡。拟议的研究将 使用来自野生型和PARP-/-小鼠的皮质培养物，神经母细胞瘤细胞， 和小鼠脑缺血模型，以研究生化 PARP和PARG激活导致细胞死亡的机制。这些研究 我们还将探索干预措施，以减少细胞死亡后的时间点， PARP 1激活。更好地理解这些过程可能会导致 针对细胞进化中下游事件的神经保护方法 缺血和其他损伤后死亡。

DESCRIPTION (provided by the applicant): The overall aim of this application is to elucidate the biochemical events leading from PARP and PARG activation to cell death, and to investigate potential interventions that could abrogate this cell death. Poly (ADP-ribose) polymerase-1 (PARP1) generates ADP-ribose polymers on many target proteins when activated by single-strand DNA breaks. PARP 1 is now well established as a mediator of cell death under conditions that lead to extensive or sustained activation. In particular, PARP1 gene disruption and PARP inhibitors have been shown to reduce brain infarction after cerebral ischemia. However, the intervening biochemical steps between PARP activation and cell death are not well understood. Our preliminary results and previously published reports suggest the involvement of secondary oxidative stress and impaired substrate delivery to mitochondria as key intermediate steps in PARP 1-mediated cell death. Providing cells with antioxidants or with TCA cycle substrates at time points after PARP 1 activation improves cell survival. Poly(ADP-ribose) glycohydrolase (PARG) binds to the (ADP-ribose) polymers produced by PARP1 and rapidly hydrolyzes them to mono(ADP-ribose). Our preliminary results also suggest that PARG is of equal importance as PARP1 in mediating oxidative and excitotoxic cell death. The studies proposed will employ cortical cultures from wild type and PARP-/- mice, neuroblastoma cells, and a mouse model of cerebral ischemia to investigate the biochemical mechanisms by which PARP and PARG activation lead to cell death. These studies will also explore interventions for reducing cell death at time points after PARP 1 activation. A better understanding of these processes could lead to neuroprotective approaches aimed at downstream events in the evolution of cell death after ischemia and other insults.