p21 inhibits Cdk1 in the absence of Cdk2 to maintain the G1/S phase DNA damage checkpoint

Ande Satyanarayana, Mary Beth Hilton, Philipp Kaldis

Research output: Contribution to journalArticlepeer-review

121 Scopus citations


Cdk1 was proposed to compensate for the loss of Cdk2. Here we present evidence that this is possible due to premature translocation of Cdk1 from the cytoplasm to the nucleus in the absence of Cdk2. We also investigated the consequence of loss of Cdk2 on the maintenance of the G1/S DNA damage checkpoint. Cdk2-/- mouse embryonic fibroblasts in vitro as well as regenerating liver cells after partial hepatectomy (PH) in Cdk2-/- mice, arrest promptly at the G1/S checkpoint in response to γ-irradiation due to activation of p53 and p21 inhibiting Cdk1. Furthermore re-entry into S phase after irradiation was delayed in Cdk2-/- cells due to prolonged and impaired DNA repair activity. In addition, Cdk2-/- mice were more sensitive to lethal irradiation compared to wild-type and displayed delayed resumption of DNA replication in regenerating liver cells. Our results suggest that the G1/S DNA damage checkpoint is intact in the absence of Cdk2, but Cdk2 is important for proper repair of the damaged DNA.

Original languageEnglish (US)
Pages (from-to)65-77
Number of pages13
JournalMolecular Biology of the Cell
Issue number1
StatePublished - Jan 2008
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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