CONICET | Buscador de Institutos y Recursos Humanos

Progesterone-induced amphibian oocyte maturation requires activation of MAPK pathway. We analyze the effect of tyrosine (tyr) kinase and Src inhibition on maturation and MAPK activation, and we evaluate the importance of caveolae-like membranes in signal transduction. Ceramide was compared to progesterone for its ability to induce tyr phosphorylation and methyl-β-cyclodextrin (MβCD) was used for cholesterol modulation. Oocytes arrested in meiosis I were pretreated with either genistein (100-300µM) or daidzein or a Src-specific inhibitor and subjected to coincubation with either progesterone or ceramide for different periods of time. A detergent-free protocol was used to isolate caveolae-like membranes. Maturation was significantly inhibited when oocytes were treated with genistein or the Src inhibitor. Oocyte tyr phosphorylation and p42 MAPK expression decreased at genistein 300 µM while Src inhibition delayed the expression of the MAPK. Ceramide-induced maturation showed an increase in oocyte tyr phosphorylation and MAPK expression and both events were inhibited by genistein. Progesterone-induced oocyte tyr phosphorylation was inhibited by MβCD. Membrane fractions from mature oocytes registered tyr phosphorylation and MAPK activation. Caveolae-like membranes showed an association with MEK1 and MAPK suggesting that they can recruit signaling molecules involved in oocyte maturation.