Conserved roles of fibroblast growth factor receptor 2 signaling in the regulation of inner cell mass development in bovine blastocysts

A common process during preimplantation mammalian development is blastocyst formation, which utilizes signaling through fibroblast growth factor receptor 2 (FGFR2), yet the mechanisms through which FGFR2 signaling affect preimplantation development in bovine embryos remain incompletely understood. Here, we used RNA-interference to investigate the in vitro development, the frequency of blastomere apoptosis, and the mRNA expression of developmental marker genes in FGF receptor 2-knockdown (FGFR2-KD) bovine embryos. A reduction in FGFR2 mRNA did not affect preimplantation development or the frequency of apoptotic blastomeres, but did enhanced proliferation of the inner cell mass in blastocysts (P < 0.05)—which differs from the phenotype reported for bovine embryos using a pharmacological approach (treatment with the pan-FGFR blocker PD173074), but agrees with previous results obtained using mouse embryos. Moreover, the expression of an epiblast marker gene, NANOG, and a primitive endoderm marker gene, GATA6, remained unchanged, whereas the expression of another primitive endoderm marker gene, HNF4A, was significantly reduced in FGFR2-KD embryos. Therefore, FGFR2 signaling appears to be associated with the regulation of inner cell mass development and proliferation during blastocyst formation in cattle. Mol. Reprod. Dev. 83: 516–525, 2016.