Tissue-specific regulatory elements in the human alcohol dehydrogenase 6 gene

The human alcohol dehydrogenase gene ADH6 is expressed at the highest levels in fetal and adult liver. We have mapped cis-acting elements that affect its expression. The sequence from bp -34 to -62 (site C) that includes the TATA box was strongly bound by nuclear proteins from liver, hepatoma cells, and fibroblasts, A truncation that removed the upstream part of site C but left the TATA homology intact dramatically reduced transcription; altering 5 bp in this region had much less effect, Part of site C can be bound by C/EBP alpha, but cotransfection with C/EBP alpha or C/EBP beta did not stimulate transcription, The proximal region did not display tissue specificity, so we cloned the upstream region to search for additional regulatory sequences, The region between -1.6 and -2.3 kb stimulated transcription in hepatoma cells and inhibited it in fibroblasts, We identified two sites in this region that affect transcription independently of their orientation. Site 1 was a negative regulatory element in fibroblasts but had no effect in hepatoma cells. Site 2 was a positive regulatory element in hepatoma cells but had no effect in fibroblasts, This combination of positive and negative regulatory elements can play a significant role in the tissue-specific expression of ADH6.