title: Artemis links ATM to G2/M checkpoint recovery via regulation of Cdk1-cyclin B.
abstract: Artemis is a phospho-protein that has been shown to have roles in V(D)J recombination, nonhomologous end-joining of double-strand breaks, and regulation of the DNA damage-induced G(2)/M cell cycle checkpoint. Here, we have identified four sites in Artemis that are phosphorylated in response to ionizing radiation (IR) and show that ATM is the major kinase responsible for these modifications. Two of the sites, S534 and S538, show rapid phosphorylation and dephosphorylation, and the other two sites, S516 and S645, exhibit rapid and prolonged phosphorylation. Mutation of both of these latter two residues results in defective recovery from the G(2)/M cell cycle checkpoint. This defective recovery is due to promotion by mutant Artemis of an enhanced interaction between unphosphorylated cyclin B and Cdk1, which in turn promotes inhibitory phosphorylation of Cdk1 by the Wee1 kinase. In addition, we show that mutant Artemis prevents Cdk1-cyclin B activation by causing its retention in the centrosome and inhibition of its nuclear import during prophase. These findings show that ATM regulates G(2)/M checkpoint recovery through inhibitory phosphorylations of Artemis that occur soon after DNA damage, thus setting a molecular switch that, hours later upon completion of DNA repair, allows activation of the Cdk1-cyclin B complex. These findings thus establish a novel function of Artemis as a regulator of the cell cycle in response to DNA damage.
authors.affiliation: Department of Cancer Genetics, University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Liyi
authors.initials: L
authors.lastname: Geng
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Zhang
authors.forename: Shu
authors.initials: S
authors.lastname: Zheng
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Legerski
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology* / Q000528:radiation effects; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D018385:Centrosome / Q000502:physiology; D019926:Cyclin B / Q000378:metabolism*; D056744:Cyclin B1; D004249:DNA Damage; D004260:DNA Repair / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004720:Endonucleases; D004789:Enzyme Activation; D006801:Humans; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D011418:Prophase / Q000235:genetics / Q000502:physiology; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011839:Radiation, Ionizing; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: C534699:CCNB1 protein, human; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; D011505:Protein-Tyrosine Kinases; C499349:WEE1 protein, human; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; C426344:DCLRE1C protein, human; D004720:Endonucleases