title: DNA damage-induced inhibition of rRNA synthesis by DNA-PK and PARP-1.
abstract: RNA synthesis and DNA replication cease after DNA damage. We studied RNA synthesis using an in situ run-on assay and found ribosomal RNA (rRNA) synthesis was inhibited 24 h after UV light, gamma radiation or DNA cross-linking by cisplatin in human cells. Cisplatin led to accumulation of cells in S phase. Inhibition of the DNA repair proteins DNA-dependent protein kinase (DNA-PK) or poly(ADP-ribose) polymerase 1 (PARP-1) prevented the DNA damage-induced block of rRNA synthesis. However, DNA-PK and PARP-1 inhibition did not prevent the cisplatin-induced arrest of cell cycle in S phase, nor did it induce de novo BrdU incorporation. Loss of DNA-PK function prevented activation of PARP-1 and its recruitment to chromatin in damaged cells, suggesting regulation of PARP-1 by DNA-PK within a pathway of DNA repair. From these results, we propose a sequential activation of DNA-PK and PARP-1 in cells arrested in S phase by DNA damage causes the interruption of rRNA synthesis after DNA damage.
authors.affiliation: Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA and Department of Surgery, Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: Anne S
authors.initials: AS
authors.lastname: Calkins
authors.forename: J Dirk
authors.initials: JD
authors.lastname: Iglehart
authors.forename: Jean-Bernard
authors.initials: JB
authors.lastname: Lazaro
mesh_terms: D045744:Cell Line, Tumor; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D015894:Genome, Human; D006801:Humans; D000072200:Ku Autoantigen; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000096:biosynthesis* / Q000235:genetics; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000187:drug effects; D059807:S Phase Cell Cycle Checkpoints; D014466:Ultraviolet Rays
chemical_list: D002843:Chromatin; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D004265:DNA Helicases; C106893:XRCC5 protein, human; D000072200:Ku Autoantigen; D002945:Cisplatin