title: Chk1 kinase negatively regulates mitotic function of Cdc25A phosphatase through 14-3-3 binding.
abstract: The order and fidelity of cell cycle events in mammals is intimately linked to the integrity of the Chk1 kinase-Cdc25A phosphatase pathway. Chk1 phosphorylation targets Cdc25A for destruction and, as shown here, inhibits interactions between Cdc25A and its mitotic substrate cyclin B1-Cdk1. Phosphorylation of Cdc25A on serine 178 and threonine 507 facilitates 14-3-3 binding, and Chk1 phosphorylates both residues in vitro. Mutation of T507 to alanine (T507A) enhanced the biological activity of Cdc25A. Cdc25A(T507A) was more efficient in binding to cyclin B1, activating cyclin B1-Cdk1, and promoting premature entry into mitosis. We propose that the Chk1/Cdc25A/14-3-3 pathway functions to prevent cells from entering into mitosis prior to replicating their genomes to ensure the fidelity of the cell division process.
authors.affiliation: Howard Hughes Medical Institute, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
authors.forename: Mei-Shya
authors.initials: MS
authors.lastname: Chen
authors.forename: Christine E
authors.initials: CE
authors.lastname: Ryan
authors.forename: Helen
authors.initials: H
authors.lastname: Piwnica-Worms
mesh_terms: D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D000071877:Checkpoint Kinase 1; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D056744:Cyclin B1; D004261:DNA Replication; D006801:Humans; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism*; D020687:cdc25 Phosphatases / Q000235:genetics / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; C534699:CCNB1 protein, human; D019926:Cyclin B; D056744:Cyclin B1; D011993:Recombinant Fusion Proteins; D013912:Threonine; D012694:Serine; D014446:Tyrosine 3-Monooxygenase; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C517004:CDC25A protein, human; D020687:cdc25 Phosphatases