Tissue-specific and steroid-dependent interaction of transcription factors with the oestrogen-inducible apoVLDL II promoter in vivo.

Using in vivo dimethylsulphate footprinting, we have analysed protein--DNA interactions within the promoter region of the oestrogen-inducible gene encoding chicken apo very low density lipoprotein II (apoVLDL II). Most of the guanosine--protein contacts found, are located within the 230-bp DNA 5' flanking the gene and can be grouped into separate protein-binding sites. Two of these sites resemble the oestrogen-responsive element (ERE) which is the target site for the oestrogen receptor. A third site has some features in common with the chicken ovalbumin upstream promoter element binding the COUP transcription factor. All protein contacts identified are present in the apoVLDL-II-expressing liver exclusively, and are not found in the hormone-naive liver, in erythrocytes or the oviduct tubular gland. Our results demonstrate the binding in vivo of a protein, presumably the oestrogen receptor, to the ERE and suggest that the hormone activates transcription by establishing a transcription complex comprising several factors at the apoVLDL II promoter.