title: Resisting arrest: recovery from checkpoint arrest through dephosphorylation of Chk1 by PP1.
abstract: The G2 DNA damage checkpoint prevents mitotic entry in the presence of damaged DNA, and thus is essential for cells to replicate with stable genetic inheritance. Whilst significant progress has been made in the past 10 years on the mechanism of checkpoint activation, little attention has been paid to how the DNA damage checkpoint is switched off to allow cell cycle re-entry. Insight into the mechanism of cell cycle re-entry was recently provided by our finding that the Schizosaccharomyces pombe type 1 phosphatase (PP1) Dis2 dephosphorylates the checkpoint effector kinase Chk1. This occurs on a site phosphorylated by the ATR homologue Rad3 in response to DNA damage, and results in Chk1 inactivation and checkpoint release. Here we discuss the implications of this finding on DNA damage checkpoint signaling, and speculate on models for checkpoint maintenance and release.
authors.affiliation: Institute for Molecular Bioscience, Queensland Bioscience Precinct, University of Queensland, St Lucia, Australia.
authors.forename: Nicole
authors.initials: N
authors.lastname: den Elzen
authors.forename: Ana
authors.initials: A
authors.lastname: Kosoy
authors.forename: Helen
authors.initials: H
authors.lastname: Christopoulos
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: O'Connell
mesh_terms: D048948:14-3-3 Proteins; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D018816:Genes, cdc; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000502:physiology; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D018797:Cell Cycle Proteins; C109867:Crb2 protein, S pombe; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins; D014446:Tyrosine 3-Monooxygenase; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605873:Chk1 protein, S pombe; C456840:rad3 protein, S pombe; D010749:Phosphoprotein Phosphatases