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Discrimination of the roles of MPF and MAP kinase in morphological changes that occur during oocyte maturation

Tomoya Kotani1, Masakane Yamashita

  • 1Laboratory of Molecular and Cellular Interactions, Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.

Developmental Biology
|December 17, 2002
PubMed

Insights

Maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) cooperate to drive amphibian oocyte maturation. Their combined action, not individual activation, orchestrates key events like germinal vesicle breakdown and spindle formation.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Molecular Biology

Background:

  • Amphibian oocyte maturation involves significant morphological changes driven by hormones.
  • Maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) are key kinases involved, but their distinct roles remain unclear.

Purpose of the Study:

  • To elucidate the specific functions of MPF and MAPK in Rana oocyte maturation.
  • To investigate the cooperative roles of MPF and MAPK in controlling oocyte morphological changes.

Main Methods:

  • Utilized Rana oocytes, which lack pre-MPF, simplifying kinase function discrimination.
  • Manipulated MPF and MAPK activities using progesterone, c-mos mRNA, cyclin B mRNA, and MAPK kinase inhibitors.
  • Observed chromosome and microtubule dynamics to assess the impact of kinase activation.

Main Results:

  • MPF alone induced germinal vesicle breakdown (GVBD), while MAPK alone reorganized microtubules during GVBD.
  • Activation of only one kinase resulted in limited maturation events.
  • Coactivation of MPF and MAPK by c-mos and cyclin B mRNA promoted nearly all maturation events, including GVBD, chromosome condensation, and spindle formation.

Conclusions:

  • MPF and MAPK act cooperatively to control the sequential morphological changes during oocyte maturation.
  • Distinct roles were identified: MPF initiates GVBD, and MAPK mediates microtubule reorganization.
  • The coordinated action of both kinases is essential for complete oocyte maturation.

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