Phosphorylation of maskin by Aurora-A participates in the control of sequential protein synthesis during Xenopus laevis oocyte maturation.
At the end of oogenesis, Xenopus laevis stage VI oocytes are arrested at the G2/M transition (prophase) waiting for progesterone to release the block and begin maturation. Progesterone triggers a cascade of phosphorylation events such as a decrease of pK(a) and an increase of maturating-promoting factor activity. Progression through meiosis was controlled by the sequential synthesis of several proteins. For instance, the MAPK kinase kinase c-Mos is the very first protein to be produced, whereas cyclin B1 appears only after meiosis I. After the meiotic cycles, the oocyte arrests at metaphase of meiosis II with an elevated c-Mos kinase activity (cytostatic factor). By using a two-hybrid screen, we have identified maskin, a protein involved in the control of mRNA sequential translation, as a binding partner of Aurora-A, a protein kinase necessary for oocyte maturation. Here we showed that, in vitro, Aurora-A directly binds to maskin and that both proteins can be co-immunoprecipitated from oocyte extracts, suggesting that they do associate in vivo. We also demonstrated that Aurora-A phosphorylates maskin on a Ser residue conserved in transforming acidic coiled coil proteins from Drosophila to human. When the phosphorylation of this Ser was inhibited in vivo by microinjection of synthetic peptides that mimic the maskin-phosphorylated sequence, we observed a premature maturation. Under these conditions, proteins such as cyclin B1 and Cdc6, which are normally detected only in meiosis II, were massively produced in meiosis I before the occurrence of the nuclear envelope breakdown. This result strongly suggests that phosphorylation of maskin by Aurora-A prevents meiosis II proteins from being produced during meiosis I.
Pascreau
Gaetan
G
Groupe Cycle Cellulaire, UMR6061 Génétique et Développement, CNRS, Université de Rennes 1, IFR97 Génomique Fonctionnelle, Faculté de Médecine, 2 Av du Pr Léon Bernard, 35043 Rennes Cedex, France.
Delcros
Jean-Guy
JG
Cremet
Jean-Yves
JY
Prigent
Claude
C
Arlot-Bonnemains
Yannick
Y
D000595:Amino Acid Sequence; D000818:Animals; D064127:Aurora Kinases; D018797:Cell Cycle Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D008540:Meiosis / Q000502:physiology*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D012694:Serine / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D018797:Cell Cycle Proteins; D010455:Peptides; D011993:Recombinant Fusion Proteins; C474872:TACC3 protein, Xenopus; D014157:Transcription Factors; D029867:Xenopus Proteins; D012694:Serine; D011494:Protein Kinases; C112134:AURKA protein, Xenopus; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases