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Protein kinase C is required for the disappearance of MPF upon artificial activation in mouse eggs
Author(s) -
Colonna Rosella,
Tatone Carla,
Francione Antonella,
Rosati Floriana,
Callaini Giuliano,
Corda Daniela,
Di Francesco Luisella
Publication year - 1997
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/(sici)1098-2795(199710)48:2<292::aid-mrd18>3.0.co;2-#
Subject(s) - calphostin c , protein kinase c , biology , calphostin , meiosis ii , oocyte activation , thapsigargin , microbiology and biotechnology , calcium , activator (genetics) , cytosol , stimulation , ionophore , medicine , endocrinology , biochemistry , kinase , oocyte , enzyme , receptor , embryo , endoplasmic reticulum , membrane
The aim of the present study was to investigate the implication of protein kinase C (PKC) in the mouse egg activation process. We used OAG (1‐oleoyl‐2‐acetyl‐sn‐glycerol) as a PKC activator, calphostin C as a specific PKC inhibitor, and the calcium ionophore A23187 as a standard parthenogenetic agent. The exposure of zona‐free eggs to 150 μM or 50 μM OAG for 10 min resulted in meiosis II completion in ∼80% of instances. By contrast, at a lower concentration (25 μM), the PKC stimulator was ineffective as parthenogenetic agent. Shortly after the application of 150 μM OAG, the cytosolic Ca 2+ concentration ([Ca 2+ ] i ) increased transiently in all the eggs examined, whereas after the addition of 50 μM OAG, [Ca 2+ ] i remained unchanged for at least 20 min. During this period, the activity of M‐phase promoting factor (MPF) dramatically decreased and most of the eggs entered anaphase except when the PKC was inhibited by calphostin C. Similarly, MPF inactivation and meiosis resumption were prevented in calphostin C‐loaded eggs following treatment with A23187, even though the ionophore‐induced Ca 2+ signalling was not affected. Taken together, our results indicate that stimulation of PKC is a sufficient and necessary event to induce meiosis resumption in mouse eggs and strongly suggest that, in this species, the mechanism by which a transient calcium burst triggers MPF inactivation involves a PKC‐dependent pathway. Mol. Reprod. Dev. 48:292–299, 1997. © 1997 Wiley‐Liss, Inc.