title: Poly(ADP-ribose) polymerase-1-induced NAD(+) depletion promotes nuclear factor-κB transcriptional activity by preventing p65 de-acetylation.
abstract: NF-κB is a transcription factor that integrates pro-inflammatory and pro-survival responses in diverse cell types. The activity of NF-κB is regulated in part by acetylation of its p65 subunit at lysine 310, which is required for transcription complex formation. De-acetylation at this site is performed by sirtuin 1(SIRT1) and possibly other sirtuins in an NAD(+) dependent manner, such that SIRT1 inhibition promotes NF-κB transcriptional activity. It is unknown, however, whether changes in NAD(+) levels can influence p65 acetylation and cellular inflammatory responses. Poly(ADP-ribose)-1 (PARP-1) is an abundant nuclear enzyme that consumes NAD(+) in the process of forming (ADP-ribose)polymers on target proteins, and extensive PARP-1 activation can reduce intracellular NAD(+) concentrations. Here we tested the idea that PARP-1 activation can regulate NF-κB transcriptional activity by reducing NAD(+) concentrations and thereby inhibiting de-acetylation of p65. Primary astrocyte cultures were treated with the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) to induce PARP-1 activation. This resulted in sustained acetylation of p65 and increased NF-κB transcriptional activity as monitored by a κB-driven eGFP reporter gene. These effects of MNNG were negated by a PARP-1 inhibitor, in PARP-1(-/-) cells, and in PARP-1(-/-) cells transfected with a catalytically inactive PARP-1 construct, thus confirming that these effects are mediated by PARP-1 catalytic activity. The effects of PARP-1 activation were replicated by a SIRT1 inhibitor, EX-527, and were reversed by exogenous NAD(+). These findings demonstrate that PARP-1-induced changes in NAD(+) levels can modulate NF-κB transcriptional activity through effects on p65 acetylation.
authors.affiliation: Department of Neurology, University of California, San Francisco, CA 94121, USA. Tiina.Kauppinen@med.umanitoba.ca
authors.forename: Tiina M
authors.initials: TM
authors.lastname: Kauppinen
authors.forename: Li
authors.initials: L
authors.lastname: Gan
authors.forename: Raymond A
authors.initials: RA
authors.lastname: Swanson
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D002227:Carbazoles / Q000494:pharmacology; D002478:Cells, Cultured; D006801:Humans; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D051379:Mice; D009243:NAD / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics* / Q000378:metabolism*; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics* / Q000378:metabolism*; D056564:Sirtuin 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D014162:Transfection; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: C550547:6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide; D002227:Carbazoles; D016328:NF-kappa B; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D009243:NAD; D008769:Methylnitronitrosoguanidine; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D019892:eIF-2 Kinase; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1