Differences in embryonic gene expression and quality indicate the benefit of epidermal growth factor receptor inhibitor during prematuration to improve competence in bovine oocytes

Abstract

The epidermal growth factor receptor (EGFR) pathway is directly involved in oocyte meiotic resumption induced by a gonadotropic stimulus. Here, we used an EGFR inhibitor (AG1478) to inhibit spontaneous meiosis resumption in bovine oocytes (EGFR− group) during 8 hr prematuration and assessed the competence of such oocytes for embryonic development, apoptosis and gene expression in comparison with Control group which was not prematured. Data are presented as mean ± SEM. Blastocysts rate on day 7 (40.81%, averaged) and hatching rate on day 9 (77.35%, averaged) were unaffected by treatment (p > 0.05). Similarly, treatment did not affect (p > 0.05) the total cell number on day 7 (119.05, averaged) and on day 9 (189.5, averaged). Apoptosis was reduced (p < 0.05) in EGFR− group day 7-embryos compared to Control group (3.7% ± 1.0 vs. 5.2% ± 0.8). Abundance of several transcripts was upregulated (p < 0.05) in EGFR− group, including genes related to embryo development and quality (NANOG and RPLP0), epigenetic regulation (H2AFZ), apoptosis (BID) and stress response (GPX4 and HIF1A). Taken together, the results presented here demonstrated a reduction in the apoptosis index and upregulation of NANOG, H2AFZ and RPLP0 mRNA levels, which are related to embryonic development. Our data suggest that temporary meiosis blockage with EGFR inhibitor during prematuration culture of bovine oocytes may be an interesting strategy to improve embryo quality.