The regulation of SV40 early gene expression in embryonal carcinoma stem cells--faithful transcriptional regulation in vitro.

We have derived from F9 murine embryonal carcinoma stem cells, and from differentiated derivatives induced with retinoic acid and cAMP, whole cell extracts which efficiently and accurately transcribe a variety of supercoiled DNA templates in vitro. These extracts and control elements from viral genomes have been used to study changes in transcriptional activity which accompany differentiation. The SV40 enhancer is inefficiently utilized in stem cells but is activated upon differentiation to parietal endoderm and the in vitro systems mimick this regulation. Mixing experiments demonstrate that the differentiated cell phenotype is dominant, suggesting that stem cells contain limiting amounts of factors required for enhancer activity. Our results may explain the developmental regulation of cellular genes with enhancer motifs in their control sequences.