Functional role of GATA3 and CDX2 in lineage specification during bovine early embryonic development

Current understandings of the initiation of the trophectoderm (TE) program during mammalian embryonic development lack evidence of how TE-associated factors such as GATA3 and CDX2 participate in bovine lineage specification. In this study, we describe effects of TE-associated factors on the expression of lineage specification marker genes such as SOX2, OCT4, NANOG, GATA6 and SOX17, by using cytosine base editor system. We successfully knockout GATA3 or CDX2 in bovine embryos with robust efficiency. However, GATA3 or CDX2 deletion does not affect the developmental potential of embryos to reach blastocyst stage. Interestingly, GATA3 deletion downregulates the NANOG expression in bovine blastocysts. Further analysis of the mosaic embryos shows that GATA3 is required for NANOG in the TE of bovine blastocysts. Single blastocyst RNA-seq analysis reveals that GATA3 deletion disrupts the transcriptome in bovine blastocysts. Altogether, we propose that GATA3 plays an important role in maintaining TE lineage program in bovine embryos and the functional role of GATA3 is species-specific.