Specific expression of homoeobox-containing genes during induced differentiation of embryonal carcinoma cells.

A teratocarcinoma stem cell line, P19S1801A1, differentiates after induction with drugs (retinoic acid or dimethyl sulfoxide) in aggregate cultures as outgrowths in vitro. We have used this model of murine embryonic differentiation to show that several homoeobox-containing genes are newly activated while others remain active throughout. Transcripts of 1.5, 1.7, 1.8, 3.9, and 5.0 kb were detected using two different DNA probes. Some of these transcripts were stage-specific but not cell-type specific. Affinity-purified antibodies to a synthetic peptide also showed the appearance of nuclear antigen in the embryonal carcinoma stem cells and in differentiated cell types in heterogeneous patterns. This study illustrates the usefulness of teratocarcinoma model systems to analyze homoeobox gene activation during embryonic development and differentiation.