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Nucleolar Arf sequesters Mdm2 and activates p53

J D Weber1, L J Taylor, M F Roussel

  • 1Howard Hughes Medical Institute, St Jude's Children's Research Hospital, Memphis, Tennessee 38105, USA.

Nature Cell Biology
|November 13, 1999
PubMed

Insights

The Ink4/Arf locus protein Arf binds Mdm2, sequestering it in the nucleolus. This prevents Mdm2 from inhibiting p53, leading to p53 activation and a new tumor suppression mechanism.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cellular Biology

Background:

  • The Ink4/Arf locus produces tumor suppressors p16Ink4a and p19Arf.
  • These proteins regulate cell proliferation via retinoblastoma and p53 pathways.
  • Mdm2 negatively regulates p53 activity through a feedback loop.

Purpose of the Study:

  • To investigate the interaction between Arf and Mdm2.
  • To elucidate the role of this interaction in p53 activation.
  • To understand the implications for tumor suppression.

Main Methods:

  • Studied the binding of Arf to Mdm2.
  • Observed co-localization of Arf and Mdm2 in the nucleolus.
  • Analyzed p53 activation in response to Arf-Mdm2 interaction.

Main Results:

  • Arf binds to Mdm2 and sequesters it within the nucleolus.
  • This sequestration disrupts the negative feedback regulation of p53 by Mdm2.
  • Arf and Mdm2 co-localize in the nucleolus upon Myc activation and during replicative senescence.
  • p53 is activated in the nucleoplasm due to this interaction.

Conclusions:

  • Arf-Mdm2 interaction in the nucleolus represents a novel mechanism for p53 activation.
  • This pathway contributes to tumor suppression by enhancing p53's antiproliferative functions.
  • Understanding this interaction offers new insights into cancer development and potential therapeutic targets.

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