IDENTIFICATION OF A TRANSCRIPTIONAL ENHANCER ELEMENT UPSTREAM FROM THE PROTO-ONCOGENE FOS

Sequences upstream from the proto-ongogene fos were shown to be essential for its transcription. Transient expression of the chloramphenicol acetyltransferase (CAT) gene linked to upstream sequences of the fos gene including its promoter reveals that sequences located 64 to 404 base pairs 5'' to the fos cap site contain a typical transcriptional enhancer. Moreover, these enhancer sequences, which are strikingly conserved between mouse and human fos genes, coincide with a deoxyribonuclease I-hypersensitive site in the chromatin. The expression of the fos-CAT fusion genes was stimulated only two to three times by the fos inducer 12-0-tetradecanoyl phorbol-13-acetate. The fos enhancer does not appear to be tissue-specific.