Mechanisms of PARP and PARG mediated cell death

描述(申请人提供)：DNA修复酶，PARP-1，已经成为脑缺血和其他条件下神经元死亡的关键决定因素。在之前的资助期间，由这笔赠款支持的工作阐明了生物能量衰竭在PARP-1介导的急性细胞死亡中的机制和作用，并确定了几种调节PARP-1活性的机制。在这些研究过程中，我们还确定了PARP-1在调节小胶质细胞激活、基质金属蛋白酶-9的释放和小胶质细胞诱导的神经元死亡中的主导作用。PARP-1抑制剂目前正在进入治疗中风、心肌缺血和其他疾病的临床试验，作为细胞保护和抗炎药物。米诺环素也是一种PARP-1抑制剂，也已进入中枢神经系统疾病的临床试验。然而，这些化合物影响炎症反应的机制仍然知之甚少。这是一个重要的翻译问题，因为炎症对中风后的大脑恢复既有有益的影响，也有有害的影响，损伤后正常大脑恢复所需的炎症反应的某些方面。第二个相关问题涉及抑制PARP-1的长期后果。鉴于PARP-1参与DNA修复，并且PARP-1缺陷小鼠的突变速度加快，PARP-1抑制剂治疗有可能增加存活细胞的DNA突变，特别是在氧化应激的背景下。累积的突变可能会影响神经元功能和长期存活。这里提出的研究将通过三个具体目标来解决这些相关问题。目的1将确定PARP抑制剂对脑缺血后炎症和恢复的特定方面的影响，目标2将确定PARP-1和PARG影响小胶质细胞激活的机制，目标3将建立PARP和PARG抑制剂对氧化应激和中风诱导的DNA突变的影响。这些研究的成功将增加我们对脑部炎症调控过程的了解，PARP-1和PARG抑制剂抑制脑部炎症的机制，以及这些药物在缺血后环境中使用时的突变潜力。

DESCRIPTION (provided by applicant): The DNA repair enzyme, PARP-1, has emerged as a critical determinant of neuronal death in brain ischemia and other conditions. Work supported by this grant in the prior funding period elucidated the mechanism and role of bioenergetic failure in PARP-1 - mediated acute cell death, and identified several mechanisms by which PARP-1 activity is regulated. In the course of these studies we also identified a dominant role for PARP-1 in regulating microglial activation, MMP-9 release, and microglial-induced neuronal death. PARP-1 inhibitors are currently entering clinical trials for the treatment of stroke, myocardial ischemia, and other conditions as both cytoprotective and anti-inflammatory agents. Minocycline is also a PARP-1 inhibitor, and has also entered clinical trials for CNS disorders. However, the mechanism by which these compounds influence the inflammatory response remains poorly understood. This is an important translational question, because inflammation has beneficial as well as deleterious effects on brain recovery from stroke, with some aspects of the inflammatory response required for normal brain recovery after injury. A second, related question concerns the long-term consequences of PARP-1 inhibition. Given that PARP-1 is involved in DNA repair, and that PARP-1 deficient mice have an accelerated rate of mutagenesis, there is the possibility that treatment with PARP-1 inhibitors could increase DNA mutations in surviving cells, particularly in the setting of oxidative stress. Accumulated mutations could impact neuronal function and long term survival. The studies proposed here will address these related questions through three specific aims. Aim 1 will establish the effect of PARP inhibitors on specific aspects of post-ischemic brain inflammation and recovery, Aim 2 will identify the mechanisms by which PARP-1 and PARG influence microglial activation, and Aim 3 will establish the effects of PARP and PARG inhibitors on DNA mutations induced by oxidative stress and stroke. Success with these studies will increase our understanding of regulatory processes in brain inflammation, the mechanisms by which PARP-1 and PARG inhibitors suppress brain inflammation, and the mutagenic potential of these agents when used in the post-ischemic setting.