Mechanisms of PARP and PARG mediated cell death

描述（由申请人提供）：DNA修复酶PARP-1已成为脑缺血和其他条件下神经元死亡的关键决定因素。在前一个资助期内，这项资助支持的工作阐明了PARP-1介导的急性细胞死亡中生物能量失效的机制和作用，并确定了PARP-1活性调节的几种机制。在这些研究过程中，我们还确定了PARP-1在调节小胶质细胞活化、MMP-9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临床试验，用于治疗中风、心肌缺血和其他疾病，作为细胞保护剂和抗炎剂。米诺环素也是一种PARP-1抑制剂，也已进入CNS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。这是一个重要的转化问题，因为炎症对中风后的脑恢复既有有益的作用，也有有害的作用，损伤后正常的脑恢复需要炎症反应的某些方面。第二个相关问题涉及PARP-1抑制的长期后果。鉴于PARP-1参与DNA修复，并且PARP-1缺陷小鼠的诱变速率加快，因此PARP-1抑制剂治疗可能会增加存活细胞中的DNA突变，特别是在氧化应激的情况下。累积的突变可能会影响神经元功能和长期生存。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。目标1将确定PARP抑制剂对缺血后脑部炎症和恢复的特定方面的影响，目标2将确定PARP-1和PARG影响小胶质细胞活化的机制，目标3将确定PARP和PARG抑制剂对DNA的影响氧化应激和中风诱导的突变。这些研究的成功将增加我们对脑炎症调节过程的理解，PARP-1和PARG抑制剂抑制脑炎症的机制，以及这些药物在缺血后环境中使用时的致突变潜力。 公共卫生相关性：中风是美国和全世界死亡和残疾的主要原因。本文提出的研究将评估一种抑制中风后大脑炎症的方法，作为改善中风恢复的一种手段。这些研究还将建立一种方法来评估中风和中风后炎症引起的大脑DNA突变。

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. PUBLIC HEALTH RELEVANCE: Stroke is a major cause of death and disability in the United States and throughout the world. Studies proposed here will evaluate an approach to suppressing inflammation in brain after stroke as a means of improving recovery from stroke. These studies will also establish a way to evaluate DNA mutations in brain caused by stroke and by post-stroke inflammation.