Plk1 promotes nuclear translocation of human Cdc25C during prophase

EMBO Rep. 2002 Apr;3(4):341-8. doi: 10.1093/embo-reports/kvf069. Epub 2002 Mar 15.


The nuclear accumulation of active M-phase promoting factor (MPF) during prophase is thought to be essential for coordinating M-phase events in vertebrate cells. The protein phosphatase Cdc25C, an activator of MPF, enters the nucleus to keep MPF active in the nucleus during prophase. However, the molecular mechanisms that control nuclear translocation of Cdc25C during prophase are unknown. We show that phosphorylation of a serine residue (Ser198) in a nuclear export signal sequence of human Cdc25C occurs during prophase and promotes nuclear localization of Cdc25C. We also show that Polo-like kinase 1 (Plk1) is responsible for this phosphorylation and that constitutively active Plk1 promotes nuclear localization of Cdc25C. Remarkably, a mutant Cdc25C in which Ser198 is replaced by alanine remains in the cytoplasm when wild-type Cdc25C accumulates in the nucleus during prophase. These results suggest that Plk1 phosphorylates Cdc25C on Ser198 and regulates nuclear translocation of Cdc25C during prophase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / metabolism*
  • Cell Nucleus / metabolism*
  • Cyclin B / metabolism
  • Cyclin B1
  • HeLa Cells
  • Humans
  • Phosphorylation
  • Prophase / physiology*
  • Protein Kinases / metabolism*
  • Protein Transport
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins
  • Serine
  • cdc25 Phosphatases / metabolism*


  • CCNB1 protein, human
  • Cell Cycle Proteins
  • Cyclin B
  • Cyclin B1
  • Proto-Oncogene Proteins
  • Serine
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1
  • CDC25C protein, human
  • cdc25 Phosphatases