title: PP2A/B55 and Fcp1 regulate Greatwall and Ensa dephosphorylation during mitotic exit.
abstract: Entry into mitosis is triggered by activation of Cdk1 and inactivation of its counteracting phosphatase PP2A/B55. Greatwall kinase inactivates PP2A/B55 via its substrates Ensa and ARPP19. Both Greatwall and Ensa/ARPP19 are regulated by phosphorylation, but the dynamic regulation of Greatwall activity and the phosphatases that control Greatwall kinase and its substrates are poorly understood. To address these questions we applied a combination of mathematical modelling and experiments using phospho-specific antibodies to monitor Greatwall, Ensa/ARPP19 and Cdk substrate phosphorylation during mitotic entry and exit. We demonstrate that PP2A/B55 is required for Gwl dephosphorylation at the essential Cdk site Thr194. Ensa/ARPP19 dephosphorylation is mediated by the RNA Polymerase II carboxy terminal domain phosphatase Fcp1. Surprisingly, inhibition or depletion of neither Fcp1 nor PP2A appears to block dephosphorylation of the bulk of mitotic Cdk1 substrates during mitotic exit. Taken together our results suggest a hierarchy of phosphatases coordinating Greatwall, Ensa/ARPP19 and Cdk substrate dephosphorylation during mitotic exit.
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Nadia
authors.initials: N
authors.lastname: Hégarat
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Clare
authors.initials: C
authors.lastname: Vesely
authors.affiliation: Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: P K
authors.initials: PK
authors.lastname: Vinod
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Cory
authors.initials: C
authors.lastname: Ocasio
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Nisha
authors.initials: N
authors.lastname: Peter
authors.affiliation: Genome Stability, Cancer Research UK, Clare Hall Laboratories, South Mimms, Herts, United Kingdom.
authors.forename: Julian
authors.initials: J
authors.lastname: Gannon
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Antony W
authors.initials: AW
authors.lastname: Oliver
authors.affiliation: Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Béla
authors.initials: B
authors.lastname: Novák
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Helfrid
authors.initials: H
authors.lastname: Hochegger
mesh_terms: D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D053263:Gene Regulatory Networks / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism; D008938:Mitosis / Q000235:genetics*; D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation / Q000235:genetics; D054648:Protein Phosphatase 2 / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism
chemical_list: D019926:Cyclin B; D008869:Microtubule-Associated Proteins; D010750:Phosphoproteins; C064321:cyclic AMP-regulated phosphoprotein 19; C555237:MASTL protein, human; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; C000588909:Fcp1 protein, human; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2