title: NAD+ repletion prevents PARP-1-induced glycolytic blockade and cell death in cultured mouse astrocytes.
abstract: Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme that is involved in DNA repair and activated by DNA damage. When activated, PARP-1 consumes NAD(+) to form ADP-ribose polymers on acceptor proteins. Extensive activation of PARP-1 leads to glycolytic blockade, energy failure, and cell death. These events have been postulated to result from NAD(+) depletion. Here, we used primary astrocyte cultures to directly test this proposal, utilizing the endogenous expression of connexin-43 hemichannels by astrocytes to manipulate intracellular NAD(+) concentrations. Activation of PARP-1 with the DNA alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) produced NAD(+) depletion, glycolytic blockade, and cell death. Cultures incubated in high (10mM) extracellular concentrations of NAD(+) after MNNG exposure showed normalization of intracellular NAD(+) concentrations. Repletion of intracellular NAD(+) in this manner completely restored glycolytic capacity and prevented cell death. These results suggest that NAD(+) depletion is the cause of glycolytic failure after PARP-1 activation.
authors.affiliation: Department of Neurology, University of California at San Francisco and Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA 94121, USA.
authors.forename: Weihai
authors.initials: W
authors.lastname: Ying
authors.forename: Philippe
authors.initials: P
authors.lastname: Garnier
authors.forename: Raymond A
authors.initials: RA
authors.lastname: Swanson
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death; D002470:Cell Survival; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D009243:NAD / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*
chemical_list: D018031:Connexin 43; D009243:NAD; D008769:Methylnitronitrosoguanidine; D011065:Poly(ADP-ribose) Polymerases; D005947:Glucose