Forkhead transcription factors contribute to execution of the mitotic programme in mammals

Nature. 2001 Oct 18;413(6857):744-7. doi: 10.1038/35099574.


Cell cycle progression is a process that is tightly controlled by internal and external signals. Environmental cues, such as those provided by growth factors, activate early signals that promote cell cycle entry. Cells that have progressed past the restriction point become independent of growth factors, and cell cycle progression is then controlled endogenously. The phosphatidylinositol 3OH kinase (PI(3)K)/protein kinase B (PKB) pathway must be activated in G1 to inactivate forkhead transcription factors (FKH-TFs) and allow cell cycle entry. Here we show that subsequent attenuation of the PI(3)K/PKB pathway is required to allow transcriptional activation of FKH-TF in G2. FKH-TF activity in G2 controls mammalian cell cycle termination, as interference with FKH transcriptional activation by disrupting PI(3)K/PKB downregulation, or by expressing a transcriptionally inactive FKH mutant, induces cell accumulation in G2/M, defective cytokinesis, and delayed transition from M to G1 of the cell cycle. We demonstrate that FKH-TFs regulate expression of mitotic genes such as cyclin B and polo-like kinase (Plk). Our results support the important role of forkhead in the control of mammalian cell cycle completion, and suggest that efficient execution of the mitotic programme depends on downregulation of PI(3)K/PKB and consequent induction of FKH transcriptional activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Cell Cycle Proteins
  • Cyclin B / genetics*
  • DNA-Binding Proteins / metabolism
  • Endoplasmic Reticulum / metabolism
  • Forkhead Box Protein O1
  • Forkhead Transcription Factors
  • G2 Phase
  • Gene Expression Regulation
  • Genes, cdc
  • Humans
  • Mice
  • Mitosis / physiology*
  • Nuclear Proteins / physiology*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation
  • Protein Kinases / genetics*
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Signal Transduction
  • Transcription Factors / metabolism
  • Transcription Factors / physiology*
  • Transcription, Genetic


  • Cell Cycle Proteins
  • Cyclin B
  • DNA-Binding Proteins
  • FOXO1 protein, human
  • Forkhead Box Protein O1
  • Forkhead Transcription Factors
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • Transcription Factors
  • Protein Kinases
  • Phosphatidylinositol 3-Kinases
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • polo-like kinase 1