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RhoA stimulates p27(Kip) degradation through its regulation of cyclin E/CDK2 activity

W Hu1, C J Bellone, J J Baldassare

  • 1Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, Missouri 63110, USA.

The Journal of Biological Chemistry
|January 28, 1999
PubMed

Insights

RhoA regulates cell cycle progression by controlling cyclin E/CDK2 activity, which is essential for p27(Kip) degradation. This pathway is key for cell proliferation in fibroblasts.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • RhoA is a key regulator of cell proliferation.
  • The Ras/RhoA pathway influences p27(Kip) degradation and cell cycle progression from G1 to S phase.

Purpose of the Study:

  • To investigate the role of RhoA in regulating cyclin E/CDK2 activity and p27(Kip) degradation in Chinese hamster embryo fibroblasts (IIC9 cells).

Main Methods:

  • Utilized dominant-negative CDK2 and constitutively active RhoA(63) expression in IIC9 cells.
  • Assessed the impact of RhoA and CDK2 manipulation on cyclin E/CDK2 activity and p27(Kip) degradation.
  • Employed cotransfection and rescue experiments with catalytically active cyclin E/CDK2.

Main Results:

  • RhoA regulates cyclin E/CDK2 activity, which is necessary for p27(Kip) degradation.
  • Dominant-negative CDK2 inhibited serum-induced cyclin E/CDK2 activity and p27(Kip) degradation.
  • Constitutively active RhoA(63) stimulated cyclin E/CDK2 activity and p27(Kip) degradation in the absence of serum.
  • Dominant-negative RhoA blocked serum-induced cyclin E/CDK2 activity and p27(Kip) degradation.

Conclusions:

  • RhoA acts upstream of cyclin E/CDK2 to regulate p27(Kip) degradation.
  • The RhoA/cyclin E/CDK2 pathway is a critical mechanism controlling cell cycle progression.

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