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Protein stability and function of p73 are modulated by a physical interaction with RanBPM in mammalian cultured cells

Sonja Kramer1, Toshinori Ozaki, Kou Miyazaki

  • 1Division of Biochemistry, Chiba Cancer Center Research Institute, 666-2 Nitona, Chuoh-ku, Chiba 260-8717, Japan.

Oncogene
|November 24, 2004
PubMed

Insights

Researchers discovered that RanBPM stabilizes the tumor suppressor protein p73 (p73), enhancing its ability to suppress growth and promote apoptosis after DNA damage. This finding reveals a new mechanism for regulating p73 levels and function.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • The tumor suppressor protein p73 plays a crucial role in cellular responses to DNA damage, including growth suppression and apoptosis.
  • The precise mechanisms regulating intracellular p73 levels and its stability remain incompletely understood.

Purpose of the Study:

  • To identify novel binding partners of p73 that influence its stability and function.
  • To elucidate the molecular interactions between p73 and its newly identified binding partner, RanBPM.

Main Methods:

  • Yeast-based two-hybrid screening to identify p73 binding partners.
  • GST pull-down assays and co-immunoprecipitation to confirm direct binding.
  • Indirect immunofluorescent staining to assess protein localization.
  • Western blotting to evaluate protein ubiquitination and half-life.

Main Results:

  • RanBPM was identified as a novel binding partner of p73alpha.
  • RanBPM directly binds to the C-terminus of p73alpha, but not p53.
  • Co-expression of RanBPM with p73alpha leads to nuclear translocation and co-localization.
  • RanBPM inhibits p73alpha ubiquitination, prolongs its half-life, and enhances its proapoptotic activity.

Conclusions:

  • RanBPM is a novel regulator of p73 stability and function.
  • RanBPM enhances the tumor-suppressive role of p73 by preventing its degradation.
  • These findings provide new insights into the molecular mechanisms controlling p73 activity in response to DNA damage.

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