Localization of embryonic stem cells lacking E-cadherin in a mouse blastocyst

Here we present our results regarding the role of E-cadherin (CDH1, cadherin 1) in the specification of embryonic stem cells (ESCs) in the embryo environment. It has been previously shown that, when forming embryoid bodies with wild-type ESCs, ESCs lacking a functional copy of the gene encoding the adhesive protein E-cadherin (Ecad^−/−) preferably sort out to the outside compartment, thus forming the primitive endoderm (PrE) lineage. However, little or no information is available regarding the dynamics of Ecad^−/− cells in the actual blastocyst, and so the aim of this work was to determine in which of the three blastocyst cell lines - trophoblast (TE), epiblast (Epi), or PrE - Ecad^−/− cells would be located in the embryo environment. For this purpose we injected ESCs into embryos at various stages of pre-implantation development. We used a H2B-GFP cell line expressing histone H2B conjugated with green fluorescent protein (H2BEGFP), as well as a Ecad^−/− cell line, in which cells exhibit weaker adhesive properties than wild-type Esc because of their allelic deficiency in the locus encoding cadherin CDH1. We have demonstrated that these cells exhibit a trend to locate in the TE and much less frequently in the Epi, but never in the PrE. We propose that this may be due to differences in the expression of genes characteristic of these cell lines within the Ecad^−/− cell colony.