Related Experiment Videos
Induction of Xenopus oocyte meiotic maturation by MAP kinase
O Haccard1, A Lewellyn, R S Hartley
1Howard Hughes Medical Institute, University of Colorado School of Medicine, Denver 80262, USA.
Abstract:
Mitogen-activated protein kinase (MAPK) is one of the protein kinases activated during meiotic maturation of Xenopus laevis oocytes. The c-Mosxe protein kinase, which has been shown to be sufficient to promote germinal vesicle breakdown (GVBD) in meiosis I, can directly activate MAP kinase kinase in vitro and leads to the activation of MAPK in vivo. Recently we have shown that constitutively activated MAPK induces metaphase arrest when injected into one blastomere of a two-cell embryo. This arrest mimics the natural arrest of vertebrate unfertilized eggs in second meiotic metaphase due to cytostatic factor and c-Mosxe activity. We show here that microinjection of constitutively activated thiophosphorylated MAPK into resting oocytes is able to activate maturation-promoting factor (MPF) and promote GVBD. These results strongly support the hypothesis that MAPK plays an important role in the pathway that links c-Mosxe to the activation of MPF.
Insights
Mitogen-activated protein kinase (MAPK) activation is crucial for Xenopus oocyte maturation. Constitutively active MAPK can induce maturation-promoting factor (MPF) activation and germinal vesicle breakdown (GVBD), supporting its role in the c-Mos pathway.
Area of Science:
- Cell Biology
- Molecular Biology
- Developmental Biology
Background:
- Mitogen-activated protein kinase (MAPK) is activated during Xenopus laevis oocyte meiotic maturation.
- c-Mos protein kinase is sufficient for germinal vesicle breakdown (GVBD) and activates MAPK.
- Constitutively active MAPK induces metaphase arrest, mimicking natural arrest in unfertilized eggs.
Purpose of the Study:
- To investigate the role of MAPK in the pathway linking c-Mos to maturation-promoting factor (MPF) activation.
- To determine if constitutively active MAPK can induce meiotic maturation in resting oocytes.
Main Methods:
- Microinjection of constitutively activated thiophosphorylated MAPK into resting Xenopus oocytes.
- Assay for maturation-promoting factor (MPF) activation.
- Assessment of germinal vesicle breakdown (GVBD).
Main Results:
- Microinjection of activated MAPK induced MPF activation.
- Microinjection of activated MAPK promoted GVBD in resting oocytes.
- These findings support MAPK's role in the c-Mos-mediated maturation pathway.
Conclusions:
- MAPK plays a significant role in the signaling pathway connecting c-Mos to MPF activation during oocyte maturation.
- MAPK is a key mediator in the transition from meiotic arrest to maturation.