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Molecular mechanisms of meiotic maturation and arrest in fish and amphibian oocytes
1Laboratory of Molecular and Cellular Interactions, Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, 060-0810, Japan.
Abstract:
Fish and amphibian oocytes provide excellent experimental systems for both biochemical and cytological analyses of regulatory mechanisms of meiotic maturation and arrest. Recent work shows that despite the adoption of common players, such as maturation-promoting factor (MPF), c-mos proto-oncogene product (Mos), and mitogen-activated protein kinase (MAPK), there is clear species-specificity in the mechanisms, probably due to the difference in the states of inactive MPF in immature oocytes. However, it has also been revealed that the mechanisms controlling meiotic maturation and arrest include ubiquitous pathways; The translational activation of masked mRNAs encoding Mos and cyclin B for initiating maturation and the Mos-MAPK pathway for maintaining metaphase arrest.
Insights
Fish and amphibian oocytes utilize common regulatory factors like maturation-promoting factor (MPF) and Mos-MAPK pathways for meiotic maturation and arrest. Species-specific differences arise from variations in inactive MPF states, yet universal pathways exist for oocyte cell cycle control.
Area of Science:
- Reproductive Biology
- Cellular and Molecular Biology
- Developmental Biology
Background:
- Oocytes from fish and amphibians are valuable models for studying meiotic maturation and arrest.
- Key regulatory molecules include maturation-promoting factor (MPF), c-mos proto-oncogene product (Mos), and mitogen-activated protein kinase (MAPK).
- Species-specific variations in inactive MPF states influence meiotic regulatory mechanisms.
Purpose of the Study:
- To investigate the conserved and divergent mechanisms controlling meiotic maturation and arrest in fish and amphibian oocytes.
- To elucidate the role of MPF, Mos, and MAPK pathways in oocyte cell cycle regulation.
- To identify ubiquitous pathways governing oocyte meiotic progression.
Main Methods:
- Biochemical analyses of oocyte regulatory factors.
- Cytological investigations of meiotic processes.
- Comparative studies across different fish and amphibian species.
Main Results:
- Common regulatory molecules (MPF, Mos, MAPK) are involved in oocyte maturation across species.
- Species-specific differences in inactive MPF states are observed.
- Ubiquitous pathways, including translational activation of Mos and cyclin B mRNAs and the Mos-MAPK cascade, are crucial for maturation and metaphase arrest.
Conclusions:
- Meiotic maturation and arrest in oocytes involve both species-specific and ubiquitous regulatory pathways.
- Translational control of Mos and cyclin B, and the Mos-MAPK pathway, are conserved mechanisms essential for oocyte cell cycle progression.
- Understanding these mechanisms provides insights into fundamental processes of cell cycle regulation in eukaryotes.