title: Intra-S-phase checkpoint activation by direct CDK2 inhibition.
abstract: To ensure proper progression through a cell cycle, checkpoints have evolved to play a surveillance role in maintaining genomic integrity. In this study, we demonstrate that loss of CDK2 activity activates an intra-S-phase checkpoint. CDK2 inhibition triggers a p53-p21 response via ATM- and ATR-dependent p53 phosphorylation at serine 15. Phosphorylation of other ATM and ATR downstream substrates, such as H2AX, NBS1, CHK1, and CHK2 is also increased. We show that during S phase when CDK2 activity is inhibited, there is an unexpected loading of the minichromosome maintenance complex onto chromatin. In addition, there is an increased number of cells with more than 4N DNA content, detected in the absence of p53, suggesting that rereplication can occur as a result of CDK2 disruption. Our findings identify an important role for CDK2 in the maintenance of genomic stability, acting via an ATM- and ATR-dependent pathway.
authors.affiliation: Molecular Oncology Laboratory, Department of Discovery Research, DNAX Research, Inc., Palo Alto, CA 94304, USA. yonghong.zhu@dnax.org
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Zhu
authors.forename: Carmen
authors.initials: C
authors.lastname: Alvarez
authors.forename: Ronald
authors.initials: R
authors.lastname: Doll
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kurata
authors.forename: Xiao Min
authors.initials: XM
authors.lastname: Schebye
authors.forename: David
authors.initials: D
authors.lastname: Parry
authors.forename: Emma
authors.initials: E
authors.lastname: Lees
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D042846:CDC2-CDC28 Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D002110:Caffeine / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002843:Chromatin / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D002843:Chromatin; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D002110:Caffeine; D012694:Serine; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2