DNA damage induces Chk1-dependent threonine-160 phosphorylation and activation of Cdk2.
Abnormal centrosome numbers arise in tumours and can cause multipolar mitoses and genome instability. Cdk2 controls normal centrosome duplication, but Chk1-dependent centrosome amplification also occurs after DNA damage. We investigated the involvement of cyclin-dependent kinases (Cdks) in DNA damage-induced centrosome amplification using cells lacking either Cdk2, or both Cdk1 and Cdk2 activity. Cdk2(-/-) DT40 cells showed robust centrosome amplification after ionizing radiation (IR), whereas Cdk1-deficient Cdk2(-/-) cells showed no centrosome amplification, demonstrating that Cdk1 can substitute for Cdk2 in this pathway. Surprisingly, we found that Cdk2 activity was upregulated by IR in wild-type but not in Chk1(-/-) DT40 cells. Cdk2 upregulation also occurred in HeLa cells after IR treatment. Chk1-dependent Cdk2 induction was not accompanied by increased levels of Cdk1, Cdk2, cyclin A or cyclin E, but activating T160 phosphorylation of Cdk2 increased after IR. Moreover, Cdk2 overexpression restored IR-induced centrosome amplification in Cdk1-deficient Cdk2(-/-) cells, but T160A mutation blocked this rescue. Our data suggest that Chk1 signalling causes centrosome amplification after IR by upregulating Cdk2 activity through activating phosphorylation.
Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
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E
Bourke
J A L
JA
Brown
S
S
Takeda
H
H
Hochegger
C G
CG
Morrison
D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D000071877:Checkpoint Kinase 1; D002645:Chickens; D051357:Cyclin-Dependent Kinase 2 / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004789:Enzyme Activation; D006801:Humans; D010766:Phosphorylation / Q000528:radiation effects; D010769:Phosphothreonine / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*
D030161:Avian Proteins; D010769:Phosphothreonine; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2