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Purification of Ubiquitinated p53 Proteins from Mammalian Cells
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Purification of Ubiquitinated p53 Proteins from Mammalian Cells

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Phosphorylation by aurora kinase A induces Mdm2-mediated destabilization and inhibition of p53

Hiroshi Katayama1, Kaori Sasai, Hidehiko Kawai

  • 1Department of Molecular Pathology, Division of Pathology & Laboratory Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.

Nature Genetics
|January 1, 2004
PubMed

Insights

Aurora kinase A (STK15/BTAK) overexpression degrades the tumor suppressor p53 by promoting its phosphorylation and ubiquitination. This destabilization of p53 contributes to cancer development by weakening cellular defenses.

Area of Science:

  • Molecular Biology
  • Cancer Biology
  • Cell Biology

Background:

  • Aurora kinase A (STK15, BTAK) is frequently overexpressed in human cancers.
  • Its overexpression is linked to centrosome amplification, chromosomal instability, and oncogenic transformation, mimicking p53 loss-of-function.
  • The p53 tumor suppressor pathway is critical for maintaining genomic stability.

Purpose of the Study:

  • To investigate the functional relationship between Aurora kinase A and the p53 tumor suppressor.
  • To elucidate the molecular mechanism by which Aurora kinase A influences p53 stability and function.

Main Methods:

  • Phosphorylation assays to detect p53 modification at Ser315.
  • Ubiquitination assays using Mdm2.
  • RNA interference (RNAi) to silence Aurora kinase A and Mdm2.
  • Cell cycle analysis (G2-M arrest).
  • Apoptosis assays (cisplatin-induced).
  • Analysis of p53 and Aurora kinase A levels in bladder tumor samples.

Main Results:

  • Aurora kinase A directly phosphorylates p53 at Ser315, targeting it for Mdm2-mediated ubiquitination and proteasomal degradation.
  • p53 degradation is dependent on active Aurora kinase A and functional Mdm2.
  • Silencing Aurora kinase A increases p53 stability, induces G2-M cell-cycle arrest, and enhances sensitivity to cisplatin-induced apoptosis.
  • Elevated Aurora kinase A expression correlates with low p53 levels in bladder tumors.

Conclusions:

  • Aurora kinase A acts as a crucial regulator of the p53 pathway by promoting p53 degradation.
  • Overexpression of Aurora kinase A contributes to oncogenesis by downregulating p53-mediated checkpoint control.
  • Targeting Aurora kinase A may represent a therapeutic strategy for cancers with wild-type p53.

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