title: Aurora-A kinase Ser349 phosphorylation is required during Xenopus laevis oocyte maturation.
abstract: Xenopus laevis Aurora-A is phosphorylated in vivo onto three amino acids: Ser53, Thr295 and Ser349. The activation of the kinase depends on its autophosphorylation on Thr295 within the T-loop. The phosphorylation of Ser53 by still unknown kinase(s) prevents its degradation. The present work focused on the regulation of Aurora-A function via Ser349 phosphorylation. Mutagenesis of Ser349 to alanine (S349A) had few impact in vitro on the capability of the kinase to autophosphorylate as well as on its activity. These data in addition to in gel kinase assays and site-specific proteolytic digestion experiments prove that Ser349 is clearly neither a primary autophosphorylation site, nor an autophosphorylation site depending on the priming phosphorylation of Thr295. Using specific antibodies, we also show that the phosphorylation of Aurora-A Ser349 is a physiological event during Xenopus oocyte maturation triggered by progesterone. A peak of phosphorylation paralleled the decrease of Aurora activity observed between meiosis I and II. In response to progesterone, X. laevis stage VI oocytes microinjected with the Aurora-A S349A mutant proceeded normally to germinal vesicle breakdown (GVBD), but degenerated rapidly soon after. Since phosphorylation of Ser349 is responsible for a decrease in kinase activity, our results suggest that a down-regulation of Aurora-A activity involving Ser349 phosphorylation is required in the process of maturation.
authors.affiliation: CNRS UMR6061 Génétique et Développement, Groupe Cycle Cellulaire, IFR-140 GFAS, Faculté de Médecine, Université Rennes 1, 2 Av du Pr Léon Bernard, 35043 Rennes Cedex, France.
authors.forename: Gaetan
authors.initials: G
authors.lastname: Pascreau
authors.forename: Jean-Guy
authors.initials: JG
authors.lastname: Delcros
authors.forename: Nathalie
authors.initials: N
authors.lastname: Morin
authors.forename: Claude
authors.initials: C
authors.lastname: Prigent
authors.forename: Yannick
authors.initials: Y
authors.lastname: Arlot-Bonnemains
mesh_terms: D000818:Animals; D064127:Aurora Kinases; D015153:Blotting, Western; D004789:Enzyme Activation / Q000502:physiology*; D015951:Factor Xa / Q000378:metabolism; D047468:Immunoprecipitation; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism*; D010766:Phosphorylation; D011374:Progesterone / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D012694:Serine; D011374:Progesterone; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D015951:Factor Xa