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Plk1 promotes nuclear translocation of human Cdc25C during prophase

Fumiko Toyoshima-Morimoto1, Eri Taniguchi, Eisuke Nishida

  • 1Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.

EMBO Reports
|March 19, 2002
PubMed

Insights

Polo-like kinase 1 (Plk1) triggers Cdc25C nuclear entry during prophase by phosphorylating Ser198. This phosphorylation event is crucial for regulating Cdc25C’s nuclear translocation and coordinating cell division events.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Nuclear accumulation of active M-phase promoting factor (MPF) coordinates M-phase events.
  • Cdc25C, an MPF activator, enters the nucleus during prophase to maintain MPF activity.
  • Mechanisms controlling Cdc25C nuclear translocation in prophase remain unclear.

Purpose of the Study:

  • To elucidate the molecular mechanisms governing Cdc25C nuclear translocation during prophase.
  • To identify the kinase responsible for regulating Cdc25C's nuclear entry.

Main Methods:

  • Phosphorylation site analysis of human Cdc25C.
  • In vitro kinase assays using Polo-like kinase 1 (Plk1).
  • Site-directed mutagenesis to create Ser198 alanine mutant Cdc25C.

Main Results:

  • Phosphorylation of serine residue 198 (Ser198) in Cdc25C's nuclear export signal promotes nuclear localization.
  • Polo-like kinase 1 (Plk1) directly phosphorylates Cdc25C on Ser198.
  • Constitutively active Plk1 enhances Cdc25C nuclear accumulation.
  • A Cdc25C Ser198 alanine mutant exhibits cytoplasmic localization during prophase.

Conclusions:

  • Plk1-mediated phosphorylation of Cdc25C on Ser198 is a key regulatory step for its nuclear translocation during prophase.
  • This mechanism ensures proper coordination of M-phase events by controlling MPF activity within the nucleus.

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