Figure 4.

In folliculated oocytes, integrin activation triggers germinal vesicle breakdown (GVBD) acceleration, and neither OGT nor O-GlcNAcylated Grb7 are recruited in the epidermal growth factor receptor (EGFR) complex. Stage VI Xenopus oocytes displaying their follicular cells layer (FC) and expressing EGFR were injected or not 1 h before EGF stimulation (5 nM) with Grb7 (20 ng) and incubated or not with 10 μM of pyrintegrin activator (Int Act) or left unstimulated. A, the GVBD attesting for meiosis progression was scored. B, the GVBD₅₀ (time of half responsive FC oocytes to undergo GVBD) was determined. C, immunodetections were performed after immunoprecipitations with anti-EGFR or anti-GST-Grb7 antibodies and followed by Western blots with antibodies against EGFR, GST (Grb7-GST), O-linked N-acetylglucosamine [GlcNAc] transferase) (OGT), integrin β1, and O-GlcNAcylation (O-GlcNAc). Experiments were repeated on 20 oocytes and three females. Statistical significance against FC was accepted for ∗p < 0.05. GST, glutathione-S-transferase.