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Activation of the G2/M cell cycle checkpoint by DNA damage prevents cells from entering mitosis. Centrosome separation is initiated in G2 phase and completed in M phase. This critical process for cell division is targeted by G2/M checkpoint. Here we show that Plk1 signaling plays an important role in regulation of centrosome separation after DNA damage. Constitutively active Plk1 overrides the inhibition of centrosome separation induced by DNA damage. This inhibition is dependent on ATM, but not on Chk2 or Chk1. Nek2 is a key regulator of centrosome separation and is a target of Plk1 in blocking centrosome separation. We found that Plk1 can phosphorylate Nek2 in vitro and interacts with Nek2 in vivo. Down-regulation of Plk1 with RNA interference prevents Nek2-induced centrosome splitting. DNA damage is known to inhibit Plk1 activity. We propose that the DNA damage-induced inhibition of Plk1 leads to inhibition of Nek2 activity and thus prevents centrosome separation.

Original publication




Journal article


J Biol Chem

Publication Date





42994 - 42999


Cell Cycle Proteins, Cell Division, Cell Line, Tumor, Centrosome, Checkpoint Kinase 1, Checkpoint Kinase 2, DNA Damage, Flow Cytometry, G1 Phase, G2 Phase, Green Fluorescent Proteins, HeLa Cells, Humans, Immunoblotting, Immunoprecipitation, Microscopy, Fluorescence, Mitosis, Mutation, NIMA-Related Kinases, Phosphoprotein Phosphatases, Phosphorylation, Plasmids, Protein Kinases, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, RNA Interference, RNA, Small Interfering, Radiation, Ionizing, S Phase, Signal Transduction, Time Factors, Transfection