title: A novel function of poly(ADP-ribose) polymerase-1 in modulation of autophagy and necrosis under oxidative stress.
abstract: Under oxidative stress, poly(ADP-ribose) polymerase-1 (PARP-1) is activated and contributes to necrotic cell death through ATP depletion. On the other hand, oxidative stress is known to stimulate autophagy, and autophagy may act as either a cell death or cell survival mechanism. This study aims to explore the regulatory role of PARP-1 in oxidative stress-mediated autophagy and necrotic cell death. Here, we first show that hydrogen peroxide (H(2)O(2)) induces necrotic cell death in Bax-/- Bak-/- mouse embryonic fibroblasts through a mechanism involving PARP-1 activation and ATP depletion. Next, we provide evidence that autophagy is activated in cells exposed to H(2)O(2). More importantly, we identify a novel autophagy signaling mechanism linking PARP-1 to the serine/threonine protein kinase LKB1-AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) pathway, leading to stimulation of autophagy. Finally, we demonstrate that autophagy plays a cytoprotective role in H(2)O(2)-induced necrotic cell death, as suppression of autophagy by knockdown of autophagy-related gene ATG5 or ATG7 greatly sensitizes H(2)O(2)-induced cell death. Taken together, these findings demonstrate a novel function of PARP-1: promotion of autophagy through the LKB1-AMPK-mTOR pathway to enhance cell survival in cells under oxidative stress.
authors.affiliation: Department of Community, Occupational & Family Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: Y-T
authors.initials: YT
authors.lastname: Wu
authors.forename: H-L
authors.initials: HL
authors.lastname: Tan
authors.forename: C-N
authors.initials: CN
authors.lastname: Ong
authors.forename: H-M
authors.initials: HM
authors.lastname: Shen
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D008954:Models, Biological; D009336:Necrosis; D018384:Oxidative Stress; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases
chemical_list: D006861:Hydrogen Peroxide; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011494:Protein Kinases; C546843:mTOR protein, mouse; D017346:Protein Serine-Threonine Kinases; C491654:Stk11 protein, mouse; D058570:TOR Serine-Threonine Kinases; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases