Plk3 Functionally Links DNA Damage to Cell Cycle Arrest and Apoptosis at Least in Part via the p53 Pathway

Abstract

Here we show that ectopic expression of a kinase-active Plk3 (Plk3-A) induced apoptosis. In response to DNA damage, the kinase activity of Plk3 was rapidly increased in an ATMdependent manner, whereas that of Plk1 was markedly inhibited. Recombinant Plk3 phosphorylated in vitro a glutathione S-transferase fusion protein containing p53, but not glutathione S-transferase alone. Recombinant Plk1 also phosphorylated p53 but on residues that differed from those targeted by Plk3. Co-immunoprecipitation and pull-down assays demonstrated that Plk3 physically interacted with p53 and that this interaction was enhanced upon DNA damage. In vitro kinase assays followed by immunoblotting showed that serine 20 of p53 was a target of Plk3. Furthermore, expression of a kinase-defective Plk3 mutant (Plk3 K52R ) resulted in significant reduction of p53 phosphorylation on serine 20, which was correlated with a decrease in the expression of p21 and with a concomitant increase in cell proliferation. These results strongly suggest that Plk3 functionally links DNA damage to cell cycle arrest and apoptosis via the p53 pathway.

p53- and p21-dependent premature APC/C–Cdh1 activation in G2 is part of the long-term response to genotoxic stress

“…During mitotic entry of the undisturbed cell cycle, Emi1 is marked for SCF bTrCPdependent degradation by Plk1-dependent phosphorylation (Hansen et al, 2004;Moshe et al, 2004). Whereas Plk1 is inhibited by the DNA damage checkpoint (Smits et al, 2000) and can therefore not account for Emi1 destabilization, its homologues Plk2 and Plk3 are activated after genotoxic stress (Xie et al, 2001;Bahassi el et al, 2002;Matthew et al, 2007) and can phosphorylate Emi1 in vitro (L Wiebusch and C Hagemeier, unpublished observation). It is thus conceivable that after DNA damage Plk2 or Plk3 substitute for Plk1 and trigger bTrCP-dependent degradation of Emi1.…”

Bcl-xL phosphorylation at Ser49 by polo kinase 3 during cell cycle progression and checkpoints

“…Observed in centrosomes and nucleoli during interphase [60,63], PLK3 is found at spindle poles and midbody during cytokinesis [59,60]. PLK3 activity increases rapidly after DNA damage in an ATMdependent manner, and is involved in G2 arrest by phosphorylating and inhibiting CDC25C phosphatase [64][65][66][67]. Its exact functions during mitosis remain unclear, but overexpression of PLK3's polo box domain, but not the kinase domain, causes cytokinesis defects, aneuploidy and cell death [58][59][60].…”

Genotoxic Stress-Induced Activation of Plk3 is Partly Mediated by Chk2

“…14 Immunoprecipitation and "pull-down" assays show that Plk3 physically interacts with p53 and that the extent of this interaction is increased in response to DNA damage. 14 These results suggest that Plk3 functionally links DNA damage to the induction of cell cycle arrest or apoptosis.…”

“…4 In response to DNA damage, the kinase activity of Plk3 was rapidly increased in tumor, or transformed, cell lines in an ATM-dependent manner. 14,15 Peptide mapping as well as in vitro phosphorylation followed by immunoblot analysis with antibodies specific for phosphorylated forms of p53 indicated that Plk3 phosphorylates p53 on physiologically relevant sites. 14 Immunoprecipitation and "pull-down" assays show that Plk3 physically interacts with p53 and that the extent of this interaction is increased in response to DNA damage.…”

“…14,15 Peptide mapping as well as in vitro phosphorylation followed by immunoblot analysis with antibodies specific for phosphorylated forms of p53 indicated that Plk3 phosphorylates p53 on physiologically relevant sites. 14 Immunoprecipitation and "pull-down" assays show that Plk3 physically interacts with p53 and that the extent of this interaction is increased in response to DNA damage. 14 These results suggest that Plk3 functionally links DNA damage to the induction of cell cycle arrest or apoptosis.…”