title: p130/p107/p105Rb-dependent transcriptional repression during DNA-damage-induced cell-cycle exit at G2.
abstract: The progression of normal cells from G2 into mitosis is stably blocked when their DNA is damaged. Tumor cells lacking p53 arrest only transiently in G2, but eventually enter mitosis. We show that an important component of the stable G2 arrest in normal cells is the transcriptional repression of more than 20 genes encoding proteins needed to enter into and progress through mitosis. Studies from a number of labs including our own have shown that, by inducing p53 and p21/WAF1, DNA damage can trigger RB-family-dependent transcriptional repression. Our studies reported here show that p130 and p107 play a key role in transcriptional repression of genes required for G2 and M in response to DNA damage. For plk1, repression is partially abrogated by loss of p130 and p107, and is completely abrogated by loss of all three RB-family proteins. Mouse cells lacking RB-family proteins do not accumulate with a 4N content of DNA when exposed to adriamycin, suggesting that all three RB-family proteins contribute to G2 arrest in response to DNA damage. Stable arrest in the presence of functional p53-to-RB signaling is probably due to the ability of cells to exit the cell cycle from G2, a conclusion supported by our observation that KI67, a marker of cell-cycle entry, is downregulated in both G1 and G2 in a p53-dependent manner.
authors.affiliation: Department of Molecular Biology, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Jackson
authors.forename: Mukesh K
authors.initials: MK
authors.lastname: Agarwal
authors.forename: Jinbo
authors.initials: J
authors.lastname: Yang
authors.forename: Patrick
authors.initials: P
authors.lastname: Bruss
authors.forename: Takeshi
authors.initials: T
authors.lastname: Uchiumi
authors.forename: Munna L
authors.initials: ML
authors.lastname: Agarwal
authors.forename: George R
authors.initials: GR
authors.lastname: Stark
authors.forename: William R
authors.initials: WR
authors.lastname: Taylor
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D049109:Cell Proliferation; D002469:Cell Separation; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D015536:Down-Regulation; D004317:Doxorubicin / Q000494:pharmacology; D005434:Flow Cytometry; D016195:G2 Phase; D006801:Humans; D019394:Ki-67 Antigen / Q000096:biosynthesis; D051379:Mice; D008938:Mitosis; D008954:Models, Biological; D009687:Nuclear Proteins / Q000502:physiology*; D011485:Protein Binding; D011506:Proteins / Q000502:physiology*; D016160:Retinoblastoma Protein / Q000502:physiology*; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D011506:Proteins; C493844:RBL1 protein, human; C493837:RBL2 protein, human; C493838:Rbl2 protein, mouse; D016160:Retinoblastoma Protein; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin; D004247:DNA