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p21 is a universal inhibitor of cyclin kinases

Y Xiong1, G J Hannon, H Zhang

  • 1Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York 11724.

Nature
|December 16, 1993
PubMed

Insights

The protein p21 acts as a universal inhibitor of cyclin-dependent kinases (CDKs), crucial for regulating cell proliferation. Its loss in transformed cells suggests a key role in cancer development and cell cycle control.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • Cell proliferation deregulation is a key feature of neoplastic transformation.
  • Altered growth control pathways impact cell-cycle machinery, but mechanisms remain unclear.
  • Viral oncoproteins induce changes in cyclin-dependent kinase (CDK) complexes in transformed cells.

Purpose of the Study:

  • To investigate the significance of proliferating cell nuclear antigen (PCNA) and p21 loss in transformed cell CDK complexes.
  • To elucidate the role of p21 in cell-cycle regulation.
  • To reconstitute quaternary cell-cycle kinase complexes in vitro.

Main Methods:

  • Molecular cloning of the p21 gene.
  • In vitro reconstitution of quaternary cell-cycle kinase complexes.
  • Assays to determine p21's effect on cyclin/CDK activity and cell proliferation.

Main Results:

  • p21 was cloned and its role in cell-cycle regulation investigated.
  • p21 was found to inhibit the activity of all tested cyclin/CDK family members.
  • Overexpression of p21 inhibited proliferation in mammalian cells.

Conclusions:

  • p21 acts as a universal inhibitor of cyclin kinases.
  • The loss of p21 from CDK complexes in transformed cells may contribute to uncontrolled proliferation.
  • p21 is a critical regulator of the cell cycle and a potential target in cancer therapy.

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