Porcine Aurora A accelerates Cyclin B and Mos synthesis and promotes meiotic resumption of porcine oocytes.
Full-grown oocytes arrested at germinal vesicle stage contain many dormant maternal mRNAs, and Aurora A has been reported to play a key role for the translation of these maternal mRNAs in Xenopus oocytes. Although the presence of Aurora A has been reported in mammals, the functions of Aurora A on the protein synthesis and the meiotic resumption have never been elucidated in mammalian oocytes. In the present study, the effects of porcine Aurora A on meiotic resumption of porcine oocytes were examined. At first, we cloned porcine Aurora A from total RNA of immature porcine oocytes by RT-PCR and obtained full-length cDNA that was 77%, 86% and 54% homologous with mouse, human and Xenopus Aurora A, respectively. The Aurora A mRNA and large amounts of protein were present throughout maturation period in porcine oocytes. The overexpression of porcine Aurora A by the mRNA injection into immature porcine oocytes had no effects on Cyclin B synthesis and meiotic resumption. Therefore we constructed a mutated Aurora A (AA-Aurora A), which was replaced the expecting inhibitory phosphorylation sites, serines 283 and 284, to non-phosphorylatable alanines. The oocytes expressed AA-Aurora A were accelerated their Cyclin B synthesis and Rsk phosphorylation, an indicator of Mos synthesis, then their meiotic resumption was promoted significantly. These results suggest for the first time in mammalian oocytes that mammalian Aurora A stimulates the protein synthesis and promotes the meiotic resumption. In addition, we identified the inhibitory phosphorylation sites of porcine Aurora A, and indicate the presence of phosphorylation-dependent regulation mechanisms in mammalian Aurora A.
Nishimura
Yukio
Y
Department of Animal Resource Sciences, Graduate School of Agricultural Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Endo
Tsutomu
T
Kano
Kiyoshi
K
Naito
Kunihiko
K
D000595:Amino Acid Sequence; D000818:Animals; D064096:Aurora Kinase A; D064127:Aurora Kinases; D001483:Base Sequence; D003001:Cloning, Molecular; D019926:Cyclin B / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D008540:Meiosis / Q000235:genetics*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D014176:Protein Biosynthesis / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017231:Proto-Oncogene Proteins c-mos / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D034421:Sus scrofa / Q000235:genetics / Q000378:metabolism / Q000502:physiology
D019926:Cyclin B; D012333:RNA, Messenger; C576918:Aurka protein, mouse; D064096:Aurora Kinase A; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D017231:Proto-Oncogene Proteins c-mos