Expression of epidermal growth factor receptor in the goat cumulus-oocyte complex

It has been previously reported that epidermal growth factor (EGF) influences meiotic maturation and development competence of oocytes in various mammalian species. The present study was undertaken to analyze the expression of the gene encoding the EGF-receptor (EGF-R) in the goat cumulus-oocyte complex during meiotic competence acquisition. Expression of EGF-R mRNA was evaluated by PCR on reverse transcribed mRNA from follicular cells and oocytes, using EGF-R specific primers designed from human cDNA. The presence of the EGF-R transcript was evidenced in follicular cells as well as in meiotically competent and incompetent oocytes. Western blot analysis performed with specific anti EGF-R antibody revealed in meiotically competent and incompetent oocytes and in follicular cells a 170 kD polypeptide corresponding to the goat EGF-R protein. In oocytes the amount of EGF-R increased with meiotic competence acquisition. EGF-R distribution was examined by indirect immunofluorescence on frozen sections of cumulus-oocyte complexes (COCs). EGF-R immunoreactivity was observed in cumulus cells and in oocytes. Staining appeared to be confined to the periphery of the cells for both oocytes and cumulus cells. In this study, we identified the main component required for signaling via EGF-R in the goat oocyte and in follicular cells. These results suggest a possible involvement of EGF in the regulation of follicular growth and oocyte maturation in goat.