title: A Wee1 checkpoint inhibits anaphase onset.
abstract: Cdk1 drives both mitotic entry and the metaphase-to-anaphase transition. Past work has shown that Wee1 inhibition of Cdk1 blocks mitotic entry. Here we show that the budding yeast Wee1 kinase, Swe1, also restrains the metaphase-to-anaphase transition by preventing Cdk1 phosphorylation and activation of the mitotic form of the anaphase-promoting complex/cyclosome (APC(Cdc20)). Deletion of SWE1 or its opposing phosphatase MIH1 (the budding yeast cdc25(+)) altered the timing of anaphase onset, and activation of the Swe1-dependent morphogenesis checkpoint or overexpression of Swe1 blocked cells in metaphase with reduced APC activity in vivo and in vitro. The morphogenesis checkpoint also depended on Cdc55, a regulatory subunit of protein phosphatase 2A (PP2A). cdc55Δ checkpoint defects were rescued by mutating 12 Cdk1 phosphorylation sites on the APC, demonstrating that the APC is a target of this checkpoint. These data suggest a model in which stepwise activation of Cdk1 and inhibition of PP2A(Cdc55) triggers anaphase onset.
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
authors.forename: Noel
authors.initials: N
authors.lastname: Lianga
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Williams
authors.forename: Erin K
authors.initials: EK
authors.lastname: Kennedy
authors.forename: Carole
authors.initials: C
authors.lastname: Doré
authors.forename: Sophie
authors.initials: S
authors.lastname: Pilon
authors.forename: Stéphanie L
authors.initials: SL
authors.lastname: Girard
authors.forename: Jean-Sebastien
authors.initials: JS
authors.lastname: Deneault
authors.forename: Adam D
authors.initials: AD
authors.lastname: Rudner
mesh_terms: D000705:Anaphase / Q000502:physiology*; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D018816:Genes, cdc / Q000502:physiology; D008677:Metaphase / Q000502:physiology*; D010766:Phosphorylation / Q000502:physiology; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology; D020666:ras-GRF1 / Q000235:genetics / Q000378:metabolism
chemical_list: C542351:CDC25 protein, S cerevisiae; C071246:CDC55 protein, S cerevisiae; D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; D020666:ras-GRF1; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases; D016203:CDC2 Protein Kinase; D054648:Protein Phosphatase 2