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PML regulates p53 stability by sequestering Mdm2 to the nucleolus

Rosa Bernardi1, Pier Paolo Scaglioni, Stephan Bergmann

  • 1Cancer Biology and Genetics Program, Department of Pathology and Medicine, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.

Nature Cell Biology
|June 15, 2004
PubMed

Insights

Promyelocytic leukaemia (PML) protein enhances p53 stability by moving Mdm2 to the nucleolus, a key mechanism for tumor suppression. This process, dependent on ATR and L11, is crucial for p53 stabilization and apoptosis induction after DNA damage.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • The promyelocytic leukaemia (PML) protein is a tumor suppressor that enhances p53 function through post-translational modifications within PML-Nuclear Bodies.
  • PML interacts with Mdm2, a p53 ubiquitin ligase, but the regulatory mechanism remains unclear.

Purpose of the Study:

  • To elucidate the mechanism by which PML regulates Mdm2 and its impact on p53 stability and tumor suppression.

Main Methods:

  • Investigated PML-Mdm2 interaction and localization after DNA damage using cell models.
  • Utilized techniques including nucleolar sequestration assays, ATR activation studies, and L11 knockdown experiments.
  • Assessed p53 stabilization, apoptosis induction, and nucleolar localization of PML and Mdm2 in wild-type and Pml(-/-) cells.

Main Results:

  • PML enhances p53 stability by sequestering Mdm2 to the nucleolus in an Arf-independent manner after DNA damage.
  • Nucleolar localization of PML is dependent on ATR activation and subsequent phosphorylation.
  • Impaired Mdm2 sequestration, p53 stabilization, and apoptosis were observed in Pml(-/-) cells.
  • PML associates with nucleolar protein L11, which is essential for PML's nucleolar localization post-DNA damage.

Conclusions:

  • PML plays a critical role in tumor suppression through a novel mechanism involving Mdm2 sequestration to the nucleolus.
  • This nucleolar pathway, regulated by ATR and L11, is vital for maintaining p53 stability and inducing apoptosis.
  • Highlights an unexpected function of PML within the nucleolar network for cancer prevention.

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