title: DNA damage-induced activation of p53 by the checkpoint kinase Chk2.
abstract: Chk2 is a protein kinase that is activated in response to DNA damage and may regulate cell cycle arrest. We generated Chk2-deficient mouse cells by gene targeting. Chk2-/- embryonic stem cells failed to maintain gamma-irradiation-induced arrest in the G2 phase of the cell cycle. Chk2-/- thymocytes were resistant to DNA damage-induced apoptosis. Chk2-/- cells were defective for p53 stabilization and for induction of p53-dependent transcripts such as p21 in response to gamma irradiation. Reintroduction of the Chk2 gene restored p53-dependent transcription in response to gamma irradiation. Chk2 directly phosphorylated p53 on serine 20, which is known to interfere with Mdm2 binding. This provides a mechanism for increased stability of p53 by prevention of ubiquitination in response to DNA damage.
authors.affiliation: The Amgen Institute, Ontario Cancer Institute, and Departments of Medical Biophysics and Immunology, University of Toronto, 620 University Avenue, Suite 706, Toronto, Ontario, M5G 2C1, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Hirao
authors.forename: Y Y
authors.initials: YY
authors.lastname: Kong
authors.forename: S
authors.initials: S
authors.lastname: Matsuoka
authors.forename: A
authors.initials: A
authors.lastname: Wakeham
authors.forename: J
authors.initials: J
authors.lastname: Ruland
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: S J
authors.initials: SJ
authors.lastname: Elledge
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
mesh_terms: D000818:Animals; D017209:Apoptosis; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D004268:DNA-Binding Proteins; D016193:G1 Phase; D016195:G2 Phase; D005720:Gamma Rays; D005786:Gene Expression Regulation; D018390:Gene Targeting; D016147:Genes, Tumor Suppressor; D016158:Genes, p53; D006801:Humans; D007399:Interphase; D051379:Mice; D009687:Nuclear Proteins; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D010768:Phosphoserine; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; C578634:CHEK2 protein, human; C578633:Chek2 protein, mouse; D017346:Protein Serine-Threonine Kinases