Structure and function of poly(ADP-ribose) polymerase-1: role in oxidative stress-related pathologies.
Poly(ADP-ribosyl) ation is a reversible post-translational protein modification implicated in the regulation of a number of biological functions. Whereas an 18 member superfamily of poly(ADP-ribose) polymerase (PARP) enzymes synthesize poly(ADP-ribose) (PAR), a single protein, PAR glycohydrolase (PARG) is responsible for the catabolism of the polymer. PARP-1 accounts for more than 90% of the poly(ADP-ribosyl)ating capacity of the cells. PARP-1 activated by DNA breaks cleaves NAD(+) into nicotinamide and ADP-ribose and uses the latter to synthesize long branching PAR polymers covalently attached to acceptor proteins including histones, DNA repair enzymes, transcription factors and PARP-1. Whereas activation of PARP-1 by mild genotoxic stimuli may facilitate DNA repair and cell survival, irreparable DNA damage triggers apoptotic or necrotic cell death. In apoptosis, early PARP activation may assist the apoptotic cascade [e.g. by stabilizing p53, by mediating the translocation of apoptosis inducing factor (AIF) from the mitochondria to the nucleus or by inhibiting early activation of DNases]. In most severe oxidative stress situations, excessive DNA damage causes over activation of PARP-1, which incapacitates the apoptotic machinery and switches the mode of cell death from apoptosis to necrosis. Besides serving as a cytotoxic mediator, PARP-1 is also involved in transcriptional regulation, most notably in the NF kappaB and AP-1 driven expression of inflammatory mediators. Pharmacological inhibition or genetic ablation of PARP-1 provided remarkable protection from tissue injury in various oxidative stress-related disease models ranging from stroke, diabetes, diabetic endothelial dysfunction, myocardial ischemia-reperfusion, shock, Parkinson's disease, arthritis, colitis to dermatitis and uveitis. These beneficial effects are attributed to inhibition of the PARP-1 mediated suicidal pathway and to reduced expression of inflammatory cytokines and other mediators (e.g. inducible nitric oxide synthase).
Virág
László
L
Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Bem tér 18/B, Hungary. lvirag@dote.hu
D000818:Animals; D017209:Apoptosis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006801:Humans; D009336:Necrosis; D018384:Oxidative Stress; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*
D004791:Enzyme Inhibitors; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011064:Poly Adenosine Diphosphate Ribose; D011065:Poly(ADP-ribose) Polymerases; D006026:Glycoside Hydrolases; C022407:poly ADP-ribose glycohydrolase