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Akt-mediated phosphorylation of CDK2 regulates its dual role in cell cycle progression and apoptosis

Subbareddy Maddika1, Sudharsana Rao Ande, Emilia Wiechec

  • 1Manitoba Institute of Cell Biology, CancerCare Manitoba, University of Manitoba, Winnipeg, MB, R3E 0V9, Canada.

Journal of Cell Science
|March 21, 2008
PubMed

Insights

Akt phosphorylates CDK2, impacting cell cycle progression and apoptosis. This pathway

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The Akt signaling pathway regulates crucial cellular processes including cell cycle progression and apoptosis.
  • Cyclin-dependent kinase 2 (CDK2) is a key regulator of the cell cycle, particularly during the S and G2 phases.

Purpose of the Study:

  • To investigate the role of Akt in regulating CDK2 activity and localization during the cell cycle.
  • To elucidate the impact of Akt-mediated CDK2 phosphorylation on cell cycle progression and apoptosis.

Main Methods:

  • In vitro and in vivo phosphorylation assays to detect Akt-mediated CDK2 phosphorylation at Threonine 39.
  • Cell cycle analysis using flow cytometry.
  • Confocal microscopy to track the subcellular localization of Akt and CDK2-cyclin-A complexes.
  • Site-directed mutagenesis to create a non-phosphorylatable CDK2 T39A mutant.

Main Results:

  • Akt phosphorylates CDK2 at Threonine 39, enhancing cyclin-A binding but not basal kinase activity.
  • Akt exhibits transient nucleo-cytoplasmic shuttling during late S and G2 phases.
  • Akt-mediated CDK2 phosphorylation induces cytoplasmic localization of the CDK2-cyclin-A complex, which is essential for S to G2-M phase transition.
  • The CDK2 T39A mutant impairs cell cycle progression.
  • Anticancer drugs like methotrexate and docetaxel constitutively activate the Akt/CDK2 pathway, promoting apoptosis.

Conclusions:

  • Transient Akt/CDK2 activation is crucial for normal cell cycle progression.
  • Constitutive activation of the Akt/CDK2 pathway, coupled with altered subcellular localization, drives apoptosis.
  • Akt is a novel regulator of CDK2, influencing both cell cycle control and programmed cell death.

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