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Yeast As a Chassis for Developing Functional Assays to Study Human P53
14:57

Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

Modulation of p53 and MDM2 activity by novel interaction with Ras-GAP binding proteins (G3BP)

M M Kim1, D Wiederschain, D Kennedy

  • 1Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA.

Oncogene
|February 14, 2007
PubMed

Insights

Ras-GTPase activating protein-SH3-domain-binding proteins (G3BPs) bind to the p53 tumor suppressor. G3BPs negatively regulate p53 by promoting its cytoplasmic localization and affecting MDM2 interactions, impacting cancer progression.

Area of Science:

  • Molecular Biology
  • Cancer Biology
  • Cell Biology

Background:

  • p53 tumor suppressor pathway inactivation is crucial in human tumorigenesis.
  • p53 can be silenced via degradation, transcriptional inhibition, or altered subcellular localization.

Purpose of the Study:

  • To investigate the role of Ras network proteins, specifically G3BP1 and G3BP2, in p53 regulation.
  • To elucidate the mechanism by which G3BPs influence p53 stability and activity.

Main Methods:

  • Proteomic approach to identify p53-interacting proteins.
  • In vitro and in vivo binding assays.
  • Expression studies of G3BPs and their effect on p53 localization and stability.
  • MDM2 interaction and ubiquitylation assays.
  • Short hairpin RNA (shRNA)-mediated knockdown of G3BP1 and G3BP2.

Main Results:

  • G3BP1 and G3BP2 bind to p53.
  • G3BP expression causes p53 redistribution from the nucleus to the cytoplasm.
  • G3BP2 interacts with MDM2, reducing MDM2-mediated p53 ubiquitylation and degradation.
  • G3BP2 expression stabilizes MDM2 and compromises its auto-ubiquitylation.
  • Knockdown of G3BP1 or G3BP2 upregulates p53 levels and activity in cancer cell lines.

Conclusions:

  • G3BP1 and G3BP2 function as negative regulators of the p53 tumor suppressor.
  • G3BP-mediated p53 regulation involves altered subcellular localization and modulation of MDM2 activity.

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