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.
Bourke
E
E
Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
Brown
J A L
JA
Takeda
S
S
Hochegger
H
H
Morrison
C G
CG
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