Exogenous delta-crystallin gene expression as probe for differentiation of teratocarcinoma stem cells.

We developed an experimental system in which differentiation of teratocarcinoma stem cell is probed by expression of stably introduced exogenous genes. We used chicken delta-crystallin gene (delta gene) and its derivative (Mo delta gene) driven by long terminal repeat (LTR) promoter of Moloney murine leukemia virus (Mo-MuLV). Neither of the genes was expressed in the undifferentiated condition. Differentiation to primitive endoderm induced by retinoic acid (RA) led to expression of delta but not Mo delta, while differentiation to more advanced endodermal cells by RA plus dibutyryl cAMP elicited Mo delta expression in addition to delta. These results are interpreted as a consequence of differential activation/suppression of gene expression through enhancer elements associated with the genes.