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Resisting arrest: recovery from checkpoint arrest through dephosphorylation of Chk1 by PP1

Nicole den Elzen1, Ana Kosoy, Helen Christopoulos

  • 1Institute for Molecular Bioscience, Queensland Bioscience Precinct, University of Queensland, St Lucia, Australia.

Cell Cycle (Georgetown, Tex.)
|March 17, 2004
PubMed

Insights

The G2 DNA damage checkpoint ensures genetic stability. We found that the phosphatase Dis2 inactivates the Chk1 kinase, releasing the cell cycle from the DNA damage checkpoint.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • The G2 DNA damage checkpoint is crucial for preventing cell division with damaged DNA, ensuring genetic stability.
  • While checkpoint activation is well-studied, the mechanisms for checkpoint deactivation and cell cycle re-entry remain less understood.

Purpose of the Study:

  • To investigate the mechanism by which the DNA damage checkpoint is switched off.
  • To identify key regulators involved in releasing the cell cycle from checkpoint arrest.

Main Methods:

  • Utilized the fission yeast Schizosaccharomyces pombe as a model organism.
  • Investigated the role of the type 1 phosphatase Dis2 in regulating the checkpoint effector kinase Chk1.

Main Results:

  • Discovered that the phosphatase Dis2 directly dephosphorylates the checkpoint effector kinase Chk1.
  • Showed that this dephosphorylation event, occurring at a site modified by Rad3, leads to Chk1 inactivation.
  • Demonstrated that Chk1 inactivation by Dis2 results in the release of the DNA damage checkpoint.

Conclusions:

  • The phosphatase Dis2 plays a critical role in the termination of the DNA damage checkpoint.
  • This finding provides insight into the molecular mechanisms governing cell cycle re-entry after DNA damage.
  • Suggests potential models for checkpoint maintenance and timely release in response to DNA damage.

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