Inhibition of mitogen activated protein kinase activity induces parthenogenetic activation and increases cyclin B accumulation during porcine oocyte maturation.
The inhibition of mitogen activated protein kinase (MAPK) activation during porcine oocyte maturation leads to decreased maturation promoting factor (MPF) activity and to the induction of parthenogenetic activation. In the present study, in order to analyze the mechanism underlying the suppression of MPF activity in MAPK-inhibited porcine oocytes, we injected mRNA of SASA-MEK, a dominant negative MAPK kinase, or antisense RNA of c-mos, a MAPK kinase kinase, into immature porcine oocyte cytoplasm. The injection of SASA-MEK mRNA or c-mos antisense RNA inhibited the MAPK activity partially or completely, respectively, decreased the MPF activity slightly or significantly, respectively, and induced parthenogenetic activation in 17.1% or 96.6% of mature oocytes, respectively, although no parthenogenetic activation was observed in the control oocytes. Immunoblotting experiments revealed that cyclin B accumulation in these MAPK-suppressed porcine oocytes was increased significantly after 50 h of culture and that a considerable amount of MPF was converted into inactive pre-MPF by hyperphosphorylation. These results indicate that the inhibition of MAPK activity in porcine oocytes did not promote cyclin B degradation but rather suppressed it; also the decrease in MPF activity in MAPK-suppressed porcine oocytes correlated with the conversion of active MPF into inactive pre-MPF.
Takakura
Ikuko
I
Department of Applied Genetics, Graduate School of Agriculture and Life Science University of Tokyo, Japan.
Naito
Kunihiko
K
Iwamori
Naoki
N
Yamashita
Masakane
M
Kume
Sachi
S
Tojo
Hideaki
H
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D019926:Cyclin B / Q000378:metabolism*; D005260:Female; D048369:MAP Kinase Kinase 1 / Q000235:genetics / Q000494:pharmacology; D016200:Maturation-Promoting Factor / Q000378:metabolism; D008540:Meiosis / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000201:enzymology / Q000254:growth & development / Q000502:physiology*; D010312:Parthenogenesis / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013552:Swine / Q000378:metabolism / Q000502:physiology*
D019926:Cyclin B; D047428:Protein Kinase Inhibitors; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1