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Purification of Ubiquitinated p53 Proteins from Mammalian Cells
10:55

Purification of Ubiquitinated p53 Proteins from Mammalian Cells

Published on: March 21, 2022

Ribosomal proteins RPL37, RPS15 and RPS20 regulate the Mdm2-p53-MdmX network

Lilyn Daftuar1, Yan Zhu, Xavier Jacq

  • 1Department of Biological Sciences, Columbia University, New York, New York, United States of America.

Plos One
|July 23, 2013
PubMed

Insights

Three ribosomal proteins (RPL37, RPS15, RPS20) bind Mdm2, stabilizing p53 and impacting the Mdm2-p53-MdmX network. These proteins regulate cancer-associated pathways through distinct mechanisms.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Signaling

Background:

  • Nucleolar changes and ribosomal protein (RP) mutations are linked to cancer.
  • RPs can inhibit Mdm2 E3 ligase activity, stabilizing p53 and activating cell cycle arrest.
  • A critical RP-Mdm2-p53 signaling pathway monitors ribosome biogenesis.

Purpose of the Study:

  • To identify novel ribosomal proteins that interact with Mdm2 and modulate the p53 pathway.
  • To investigate the mechanisms by which these RPs affect Mdm2, p53, and MdmX.
  • To understand how these RPs influence cancer-related cellular processes like cell death and cell cycle arrest.

Main Methods:

  • Ectopic expression of RPL37, RPS15, and RPS20 in p53-null and p53-containing cell lines.
  • Western blotting to detect stabilization of Flag-tagged Mdm2, HA-tagged p53, and endogenous p53.
  • Assessment of Mdm2 E3 ligase activity inhibition.
  • Analysis of p53 target gene regulation and MdmX levels.

Main Results:

  • RPL37, RPS15, and RPS20 were identified as RPs that bind Mdm2 and activate p53.
  • These RPs stabilize both Mdm2 and p53 by inhibiting Mdm2's E3 ubiquitin ligase activity.
  • Each RP induced cell death and cell cycle arrest but regulated distinct p53 target genes.
  • RPL37, RPS15, and RPS20 differentially downregulated MdmX levels.

Conclusions:

  • RPL37, RPS15, and RPS20 are novel regulators of the Mdm2-p53-MdmX network.
  • These RPs modulate cancer-associated signaling through distinct mechanistic approaches.
  • Understanding these RP-mediated pathways offers insights into cancer surveillance and potential therapeutic strategies.

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