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Localisation of phosphorylated MAP kinase during the transition from meiosis I to meiosis II in pig oocytes

Published online by Cambridge University Press:  01 May 2000

Jibak Lee ,
Takashi Miyano  and
Robert M. Moor
Jibak Lee
Affiliation:
Laboratory of Protein Function, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK. The Graduate School of Science and Technology, Kobe University, Nadu-ku, Kobe 657-8501, Japan.
Takashi Miyano
Affiliation:
Laboratory of Animal Breeding and Reproduction, Kobe University, Nada-ku, Kobe 657-8501, Japan.
Robert M. Moor
Affiliation:
Laboratory of Protein Function, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK.
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Abstract

Mitogen-activated protein kinase (MAPK) has been reported to be involved in oocyte maturation in all animals so far examined. In the present study we investigate the expression and localisation of active phosphorylated MAPKs (p44ERK1/p42ERK2) during maturation of pig oocytes. In immunoblot analysis using anti-p44ERK1 antibody which recognised both active and inactive forms of p44ERK1 and p42ERK2, we confirmed that MAPKs were phosphorylatred around the time of germinal vesicle breakdown (GVBD) and the active phosphorylated MAPKs (pMAKs) were maintained until metaphase II, as has been reported. On immunofluorescent confocal microscopy using anti-pMAPK antibody which recognised only phosphorylated forms of MAPKs, pMAPK was localised at the spindle poles in pig mitotic cells. On the other hand, in pig oocytes, no signal was detected during GV stage. After GVBD, the area around condensed chromosomes was preferentially stained at metaphase I although whole cytoplasm was faintly stained. At early anaphase I, the polar regions of the meiotic spindle were prominently stained. However, during the progression of anaphase I and telophase I pMAPK was detected at the mid-zone of the elongated spindle, gradually becoming concentrated at the centre. Finally, at the time of emission of the first polar body, pMAPK was detected as a ring-like structure between the condensed chromosomes and the first polar body, and the staining was maintained even after the metaphase II spindle was formed. The inhibition of MAPK activity with the MAPK kinase inhibitor U0126 during the meiosis I/meiosis II transition suppressed chromosome separation, first polar body emission and formation of the metaphase II spindle. From these results, we propose that the spindle-associated pMAPKs play an important role in the events occurring during the meiosis I/meiosis II transition, such as chromosome separation, spindle elongation and cleavage furrow formation in pig oocytes.

Keywords

MAP kinaseMeiosisPig oocytesSpindleU0126
Type
Research Article
Information
Zygote , Volume 8 , Issue 2 , May 2000 , pp. 119 - 125
Copyright
2000 Cambridge University Press

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