The effect of antisense oligonucleotides to Cdx2 on the development of mouse embryos in vitro

The Drosophila homeobox gene caudal is thought to play a role in segmentation and the formation of posterior structures in the fly. One of the mouse homologs, Cdx2, is first expressed in embryonic tissue at 8.5 days, being detected in the tail bud, neural tube and hindgut. To gain insight into the role of Cdx2 in mouse development, we have applied antisense technology to the mouse embryo culture system. Two antisense and two mismatch (control) oligonucleotides were injected into the amniotic cavity of 5-7 somite embryos, thus coming into direct contact with the dorsal surface of the embryo. The results showed that all constructs were biologically active, the nature of the abnormalities produced probably reflecting the developmental stage at which the embryo was exposed. However, the antisense constructs were clearly more potent than their mismatch controls and we conclude that some specificity of action is responsible for this effect. In our view, this does not necessarily imply that Cdx2 has a direct role in brain morphogenesis.