Culture medium, gas atmosphere and MAPK inhibition affect regulation of RNA-binding protein targets during mouse preimplantation development

Abstract

During oogenesis, mammalian oocytes accumulate maternal mRNAs that support the embryo until embryonic genome activation. RNA-binding proteins (RBP) may regulate the stability and turnover of maternal and embryonic mRNAs. We hypothesised that varying embryo culture conditions, such as culture medium, oxygen tension and MAPK inhibition, affects regulation of RBPs and their targets during preimplantation development. STAU1, ELAVL1, KHSRP and ZFP36 proteins and mRNAs were detected throughout mouse preimplantation development, whereasElavl2mRNA decreased after the two-cell stage. Potential target mRNAs of RBP regulation,Gclc,Slc2a1andSlc7a1were detected during mouse preimplantation development.GclcmRNA was significantly elevated in embryos cultured in Whitten's medium compared with embryos cultured in KSOMaa, andGclcmRNA was elevated under high-oxygen conditions. Inhibition of the p38 MAPK pathway reducedSlc7a1mRNA expression while inhibition of ERK increasedSlc2a1mRNA expression. The half-lives of the potential RBP mRNA targets are not regulated in parallel;Slc2a1mRNA displayed the longest half-life. Our results indicate that mRNAs and proteins encoding five RBPs are present during preimplantation development and more importantly, demonstrate that expression of RBP target mRNAs are regulated by culture medium, gas atmosphere and MAPK pathways.