title: CDC25B phosphorylated by pEg3 localizes to the centrosome and the spindle poles at mitosis.
abstract: The phosphatase CDC25B is one of the key regulators that control entry into mitosis through the dephosphorylation and subsequent activation of the cyclin-dependent kinases. Here we study the phosphorylation of CDC25B at mitosis by the kinase pEg3, a member of the KIN1/PAR-1/MARK family. Using mass spectrometry analysis we demonstrate that CDC25B is phosphorylated in vitro by pEg3 on serine 169, a residue that lies within the B domain. Moreover, using phosphoepitope-specific antibodies we show that serine 169 is phosphorylated in vivo, that this phosphorylated form of CDC25B accumulates during mitosis, and is localized to the centrosomes. This labelling is abrogated when pEg3 expression is repressed by RNA interference. Taken together, these results support a model in which pEg3 contributes to the control of progression through mitosis by phosphorylation of the CDC25 phosphatases.
authors.affiliation: LBCMCP-CNRS UMR5088- IFR109 Institut d'Exploration Fonctionnelle des Génomes, Université Paul Sabatier, Toulouse, France.
authors.forename: Gladys
authors.initials: G
authors.lastname: Mirey
authors.forename: Isabelle
authors.initials: I
authors.lastname: Chartrain
authors.forename: Carine
authors.initials: C
authors.lastname: Froment
authors.forename: Muriel
authors.initials: M
authors.lastname: Quaranta
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bouché
authors.forename: Bernard
authors.initials: B
authors.lastname: Monsarrat
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Tassan
authors.forename: Bernard
authors.initials: B
authors.lastname: Ducommun
mesh_terms: D000595:Amino Acid Sequence; D018385:Centrosome / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D021381:Protein Transport; D011994:Recombinant Proteins; D012694:Serine; D013057:Spectrum Analysis; D008941:Spindle Apparatus / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D020687:cdc25 Phosphatases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D051741:Kruppel-Like Transcription Factors; C490820:PEG3 protein, human; D011994:Recombinant Proteins; D014157:Transcription Factors; D012694:Serine; D011494:Protein Kinases; D020687:cdc25 Phosphatases