title: Poly(ADP-ribose) polymerase-1 is a positive regulator of the p53-mediated G1 arrest response following ionizing radiation.
abstract: Poly(ADP-ribose) polymerase-1 (PARP-1) and the p53 tumor suppressor protein are both involved in the cellular response to genotoxic stress. Upon binding to the site of DNA strand breakage, PARP-1 is activated, leading to rapid and transient poly(ADP-ribosyl)ation of nuclear proteins using NAD+ as substrate. To investigate the role of PARP-1 in the p53 response to ionizing radiation in human cells, PARP-1 function was disrupted in wild-type p53 expressing MCF-7 and BJ/TERT cells using two strategies: chemical inhibition with 1,5-dihydroxyisoquinoline, and trans-dominant inhibition by overexpression of the PARP-1 DNA-binding domain. Although a number of proteins can catalyze poly(ADP-ribosyl)ation in addition to PARP-1, we show that PARP-1 is the only detectable active species in BJ/TERT and MCF-7 cells. 1,5-Dihydroxyisoquinoline treatment prior to ionizing radiation delayed and attenuated the induction of two p53-responsive genes, p21 and mdm-2, and led to suppression of the p53-mediated G1-arrest response in MCF-7 and BJ/TERT cells. Trans-dominant inhibition of PARP-1 by overexpression of the PARP-1 DNA-binding domain in MCF-7 cells also led to a delay and attenuation in p21 induction and suppression of the p53-mediated G1 arrest response to ionizing radiation. Hence, inhibition of endogenous PARP-1 function suppresses the transactivation function of p53 in response to ionizing radiation. This study establishes PARP-1 as a critical regulator of the p53 response to DNA damage.
authors.affiliation: Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
authors.forename: Sonya
authors.initials: S
authors.lastname: Wieler
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Gagné
authors.forename: Homayoun
authors.initials: H
authors.lastname: Vaziri
authors.forename: Guy G
authors.initials: GG
authors.lastname: Poirier
authors.forename: Samuel
authors.initials: S
authors.lastname: Benchimol
mesh_terms: D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016193:G1 Phase / Q000502:physiology* / Q000528:radiation effects; D015870:Gene Expression; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D009243:NAD / Q000494:pharmacology; D009687:Nuclear Proteins; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D051736:Proto-Oncogene Proteins c-mdm2; D011839:Radiation, Ionizing; D015533:Transcriptional Activation / Q000528:radiation effects; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D007546:Isoquinolines; D009687:Nuclear Proteins; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D009243:NAD; C095653:1,5-dihydroxyisoquinoline; D004247:DNA; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D011065:Poly(ADP-ribose) Polymerases; D004121:Dimethyl Sulfoxide