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The Wip1 phosphatase (PPM1D) antagonizes activation of the Chk2 tumour suppressor kinase

M Oliva-Trastoy1, V Berthonaud, A Chevalier

  • 1Service de Biochimie et de Génétique Moléculaire, CEA/Saclay, Gif-sur-Yvette, France.

Oncogene
|August 29, 2006
PubMed

Insights

The oncogenic protein Wip1, a type 2C phosphatase, dephosphorylates and inhibits the Chk2 kinase, opposing DNA damage checkpoint activation in mammalian cells. This pathway is conserved from yeast to humans.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • Type 2C protein phosphatases (PP2C) regulate DNA damage responses.
  • Ptc2 and Ptc3 are crucial for DNA checkpoint inactivation in yeast.
  • Conserved mechanisms in DNA damage response pathways are vital for understanding cancer.

Purpose of the Study:

  • To investigate the role of Wip1, a PP2C phosphatase, in mammalian DNA damage response.
  • To determine if Wip1 regulates Chk2 kinase activity in response to DNA damage.
  • To confirm the conservation of PP2C-mediated DNA checkpoint regulation in human cells.

Main Methods:

  • Investigated the interaction between Wip1 and Chk2.
  • Assessed the effect of Wip1 on Chk2 phosphorylation at Thr68.
  • Utilized HCT15 colorectal cancer cells with functional Chk2 to study checkpoint regulation.
  • Examined the impact of Wip1 overexpression on the G2/M DNA damage checkpoint.

Main Results:

  • Wip1, a PP2C phosphatase, dephosphorylates phospho-Thr68 on Chk2, opposing ATM-mediated activation.
  • Wip1 inhibits Chk2 kinase activity after ionizing irradiation.
  • Wip1 overexpression suppresses Chk2's role in the G2/M DNA damage checkpoint in HCT15 cells.

Conclusions:

  • Wip1 is a key phosphatase that regulates Chk2 activity in the DNA damage response.
  • The pathway involving PP2C phosphatases in DNA checkpoint control is conserved in mammalian cells.
  • Wip1's role in opposing Chk2 activation highlights its significance in cancer biology.

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