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Ribosomal S6 kinase p90rsk and mRNA cap-binding protein eIF4E phosphorylations correlate with MAP kinase activation

A C Gavin1, S Schorderet-Slatkine

  • 1Clinique de Stérilité et d'Endocrinologie Gynécologique, Department of Obstetrics and Gynaecology, Hôpital Cantonal Universitaire, Geneva,Switzerland.

Molecular Reproduction and Development
|March 1, 1997
PubMed

Insights

Mouse oocyte maturation involves M-phase entry regulated by protein phosphorylation and mRNA translation. MAP kinases and p90rsk activation are key to this process, influencing eIF4E and S6 kinase activity.

Area of Science:

  • Cell biology
  • Molecular biology
  • Developmental biology

Background:

  • Meiotic reinitiation in mouse oocytes requires precise regulation of M-phase entry.
  • This regulation involves dynamic changes in protein phosphorylation and mRNA translation.
  • Key signaling pathways controlling these events remain incompletely understood.

Purpose of the Study:

  • To investigate the signaling pathways regulating M-phase entry during mouse oocyte meiotic reinitiation.
  • To determine the roles of MAP kinase, histone H1 kinase, and S6 kinase in this process.
  • To elucidate the involvement of eIF4E phosphorylation and specific kinases like p90rsk and p70s6k.

Main Methods:

  • Utilized okadaic acid and cycloheximide to modulate kinase activities.
  • Assessed the activation and phosphorylation status of M-phase kinases, S6 kinase, eIF4E, p90rsk, and p70s6k.
  • Correlated kinase activity with oocyte maturation stages.

Main Results:

  • M-phase kinases (MAP kinase, histone H1 kinase), S6 kinase, and eIF4E phosphorylation were activated during meiotic reinitiation.
  • MAP kinases appear involved in eIF4E phosphorylation and S6 kinase activation.
  • p90rsk, not p70s6k, was phosphorylated and activated, correlating with increased S6 kinase activity, suggesting its primary role.

Conclusions:

  • p90rsk activation is the main driver of increased S6 kinase activity during mouse oocyte maturation.
  • MAP kinase signaling contributes to eIF4E phosphorylation and S6 kinase activation.
  • These pathways are crucial for physiological M-phase induction and premature mitotic events.

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