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Physical and functional interactions of the Arf tumor suppressor protein with nucleophosmin/B23

David Bertwistle1, Masataka Sugimoto, Charles J Sherr

  • 1Howard Hughes Medical Institute and Department of Genetics & Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.

Molecular and Cellular Biology
|January 20, 2004
PubMed

Insights

The Arf tumor suppressor interacts with nucleophosmin/B23 (NPM), a key ribosomal protein. This interaction is crucial for Arf

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Oncology

Background:

  • The Arf tumor suppressor is a critical regulator of cell cycle progression.
  • Arf functions through both p53-dependent and p53-independent pathways, including the modulation of rRNA processing.

Purpose of the Study:

  • To investigate the molecular mechanisms by which Arf inhibits cell cycle progression.
  • To identify and characterize proteins that interact with p19(Arf) during cell cycle arrest.

Main Methods:

  • Tandem-affinity purification of p19(Arf) and associated proteins from mouse fibroblasts.
  • Co-immunoprecipitation and biochemical assays to analyze protein interactions.
  • Cellular localization studies using microscopy in engineered cell lines.

Main Results:

  • p19(Arf) specifically associates with nucleolar and ribosomal proteins, notably nucleophosmin/B23 (NPM).
  • The interaction between p19(Arf) and NPM involves specific domains on both proteins and occurs independently of p53 and Mdm2.
  • p19(Arf) and NPM co-localize in large molecular weight complexes (2-5 MDa), and NPM mutants can disrupt this interaction and override Arf's function.

Conclusions:

  • The interaction between Arf and NPM is a significant p53-independent mechanism for Arf tumor suppressor activity.
  • This interaction is critical for Arf's role in regulating rRNA processing and cell cycle progression.

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