title: M-phase MELK activity is regulated by MPF and MAPK.
abstract: The protein kinase MELK is implicated in the control of cell proliferation, cell cycle and mRNA splicing. We previously showed that MELK activity is correlated with its phosphorylation level, is cell cycle dependent, and maximal during mitosis. Here we report on the identification of T414, T449, T451, T481 and S498 as residues phosphorylated in Xenopus MELK (xMELK) in M-phase egg extract. Phosphorylations of T449, T451, T481 are specifically detected during mitosis. Results obtained in vivo showed that MPF and MAPK pathways are involved in xMELK phosphorylation. In vitro, MPF and MAPK directly phosphorylate xMELK and MPF phosphorylates xMELK on T481. In addition, phosphorylation by MPF and MAPK enhances MELK activity in vitro. Taken together our results indicate that MELK phosphorylation by MPF and MAPK enhance its activity during M-phase.
authors.affiliation: CNRS UMR 6061 Génétique et Développement, Université de Rennes, Rennes, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Badouel
authors.forename: Roman
authors.initials: R
authors.lastname: Körner
authors.forename: Marie
authors.initials: M
authors.lastname: Frank-Vaillant
authors.forename: Anne
authors.initials: A
authors.lastname: Couturier
authors.forename: Erich A
authors.initials: EA
authors.lastname: Nigg
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Tassan
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division; D002460:Cell Line; D020935:MAP Kinase Signaling System; D016200:Maturation-Promoting Factor / Q000378:metabolism*; D008938:Mitosis; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D029867:Xenopus Proteins / Q000378:metabolism* / Q000502:physiology*; D014982:Xenopus laevis
chemical_list: D012333:RNA, Messenger; D029867:Xenopus Proteins; D017346:Protein Serine-Threonine Kinases; D016200:Maturation-Promoting Factor