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Activity of maturation promoting factor (MPF) and mitogen-activated protein kinase (MAPK) after parthenogenetic

L Bogliolo1, S Ledda, G Leoni

  • 1Obstetrics Section of the Institute of General Pathology, Pathological Anatomy and Veterinary Obstetrics-Surgery Clinic, University of Sassari, Sassari, Italy. vetfis@ssmain.uniss.it

Cloning
|October 13, 2005
PubMed

Insights

Maturation promoting factor (MPF) and mitogen-activated protein kinase (MAPK) regulate cell cycles. Their activity dynamics after oocyte activation are crucial for cloning, with MPF levels rising but failing to induce GVBD in fusion partners.

Area of Science:

  • Cell Biology
  • Reproductive Biology
  • Molecular Biology

Background:

  • Maturation promoting factor (MPF) and mitogen-activated protein kinase (MAPK) are critical regulators of meiotic and mitotic cell cycles.
  • Understanding their activity dynamics during the meiosis-to-mitosis transition is vital for nuclear transfer cloning.
  • Ovine oocytes serve as a model system to investigate these cell cycle regulatory mechanisms.

Purpose of the Study:

  • To assay changes in MPF and MAP kinase activity in vitro matured ovine oocytes post-chemical activation.
  • To evaluate the effect of 6-dimethylaminopurine (6-DMAP) on these kinase activities.
  • To determine the biological significance of MPF fluctuations by fusing activated oocytes with GV-staged partners.

Main Methods:

  • In vitro maturation of ovine oocytes.
  • Chemical activation of oocytes.
  • Culture of activated oocytes with or without 6-DMAP for 12 hours.
  • Assay of MPF and MAP kinase activity.
  • Fusion of activated MII oocytes with GV-staged oocytes.

Main Results:

  • MPF activity rapidly decreased post-activation, then increased significantly by 12 hours, reaching 80% of MII levels.
  • MAPK activity decreased to a low level within 4 hours, then gradually increased but remained below 30% of MII values.
  • 6-DMAP treatment did not alter the kinetics of MPF or MAPK activity.
  • Fusion of MII oocytes with GV partners induced GV breakdown, but high MPF activity at 8-12 hours post-activation did not induce GVBD in fusion partners.

Conclusions:

  • MPF and MAPK exhibit distinct dynamic changes following oocyte activation.
  • The observed MPF reactivation is insufficient to induce nuclear envelope breakdown in a partner oocyte.
  • These findings provide insights into the complex regulation of cell cycle transitions relevant to cloning technologies.

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