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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

Essential role of ribosomal protein L11 in mediating growth inhibition-induced p53 activation

Krishna P Bhat1, Koji Itahana, Aiwen Jin

  • 1Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030-4009, USA.

The EMBO Journal
|May 21, 2004
PubMed

Insights

Ribosomal protein L11 normally suppresses HDM2, but its interaction is controlled by cellular location. Growth inhibition causes L11 to move to the nucleoplasm, activating p53 by inhibiting HDM2.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Cancer Research

Background:

  • Ribosomal protein L11 (L11) inhibits HDM2's E3 ligase activity, activating the tumor suppressor p53.
  • L11 is a component of the 60S ribosomal subunit but does not activate p53 under normal growth conditions.

Purpose of the Study:

  • To investigate the mechanisms controlling the L11-HDM2 interaction and p53 activation.
  • To understand how growth inhibitory signals are relayed to p53 via L11.

Main Methods:

  • Knockdown of L11 expression.
  • Serum starvation and low-dose actinomycin D treatment.
  • Analysis of L11 localization (nucleolus vs. nucleoplasm) and complex formation with HDM2.

Main Results:

  • L11 knockdown significantly attenuates p53 induction under growth inhibitory conditions.
  • L11 levels are constant during serum starvation, unaffected by transcription or protein stability.
  • Serum starvation induces L11 translocation from the nucleolus to the nucleoplasm, where it forms a complex with HDM2.

Conclusions:

  • The nucleolus acts as a physical barrier preventing L11-HDM2 interaction during normal growth.
  • Growth inhibition, possibly via suppressed rRNA production, triggers L11 translocation, leading to p53 activation through HDM2 inhibition.

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