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CDK2-dependent phosphorylation of FOXO1 as an apoptotic response to DNA damage

Haojie Huang1, Kevin M Regan, Zhenkun Lou

  • 1Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.

Science (New York, N.Y.)
|October 14, 2006
PubMed

Insights

Cyclin-dependent kinase 2 (CDK2) regulates cell survival after DNA damage by controlling FOXO1 transcription factor activity. DNA damage inhibits CDK2, preventing FOXO1 phosphorylation and promoting cell death.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Cyclin-dependent kinase 2 (CDK2) activity is typically inhibited following DNA damage, crucial for cell cycle arrest and DNA repair.
  • The role of CDK2 in cellular survival under genotoxic stress remains unclear, despite the known importance of Forkhead box O (FOXO) transcription factors in cell survival.

Purpose of the Study:

  • To investigate the functional interaction between CDK2 and FOXO1 in regulating cell survival following DNA damage.
  • To elucidate the mechanism by which CDK2 influences FOXO1 activity and subsequent apoptotic cell death.

Main Methods:

  • In vitro and in vivo phosphorylation assays to determine CDK2-mediated phosphorylation of FOXO1 at Serine-249 (Ser249).
  • Small interfering RNA (siRNA) to silence FOXO1 expression and assess its impact on DNA damage-induced cell death.
  • Restoration of FOXO1 expression to confirm the role of Ser249 phosphorylation in cell survival.

Main Results:

  • CDK2 specifically phosphorylates FOXO1 at Ser249, leading to its cytoplasmic localization and inhibition.
  • DNA damage abrogates CDK2-FOXO1 phosphorylation via the Chk1/Chk2-dependent cell cycle checkpoint pathway.
  • FOXO1 silencing reduces DNA damage-induced cell death, an effect reversible by restoring FOXO1 expression dependent on Ser249 phosphorylation.

Conclusions:

  • The functional interaction between CDK2 and FOXO1 provides a novel mechanism for regulating apoptotic cell death in response to DNA strand breaks.
  • CDK2-mediated phosphorylation of FOXO1 is a critical determinant of cell survival or death following genotoxic stress.

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