Role of NANOG in Goat Pre-Implantation Embryonic Development

Pluripotent cell-specific gene including Nanog plays essentialroles in regulation of signaling pathways, especially in maintenanceand induction of pluripotency in embryonic stem cells(ESC) and inner cell mass (ICM) in many species includingmouse and human. Unlike in these species, the molecular featuresand transcription regulation of NANOG gene in goatis not well defined. In this study, by knockdown of NANOGmRNA in goat embryos, we examined the role of this gene onearly embryonic development. Therefore, ۸-۱۰ pl of NANOGor scrambled (SCR) siRNA were injected into presumptive zygotes.Subsequently cleavage and blastocyst formation rateswere assessed along with gene expression analysis in ۶-۸ celland blastocyst stage. In siRNA groups, cleavage and blastocystrates were slightly but insignificantly lower than the controland SCR groups, however, embryos with reduced expression ofNANOG presented reduction in number of trophectoderm andtotal cells in blastocysts. Gene expression analysis of developmentallyimportant genes, including: SOX۲, OCT۴ and NANOG,showed that this reduction results in significant increasein expression of SOX۲ and OCT۴ and amid the conceivabletarget genes (CDX۲, REX۱ and GATA۴) of this network, onlyGATA۴ displayed increased expression. Therefore, we concludedthat NANOG is likely to be essential for proliferation oftrophoblastic cells.