REGULATION OF HUMAN ALCOHOL-DEHYDROGENASE GENE ADH7 - IMPORTANCE OF AN AP-1 SITE

The structure and function of the human alcohol dehydrogenase 7 (ADH7) promoter were analyzed, A promoter fragment extending to bp -232 func tioned well in H4IIE-C3, CV-1, and HeLa cells, whereas the region exte nding further upstream to bp -799 had no significant effect on activit y, We identified cis-acting elements in the proximal 232 bp and examin ed their effect on promoter activity. Mutation of site A, where c-Jun bound, caused a drastic decrease in the promoter activity in H4IIE-C3 and CV-1 cells, suggesting that AP-1 plays an important role in the re gulation of ADH7, Mutation of site B also caused a large drop in promo ter activity in both cell lines; C/EBP alpha can bind to this site, bu t because the site affects activity approximately equally in CV-1 cell s that lack C/EBP alpha and in H4IIE-C3 cells that contain low levels, other proteins are likely to play the major roles in vivo, Mutation o f site C, where C/EBP bound and c-Jun bound weakly, had different effe cts in the two cell lines: in H4IIE-C3 cells, the site C mutation did not significantly increase promoter activity, whereas in CV-1 cells, w hich lack C/EBP alpha, it led to a doubling of activity, Surprisingly, cotransfection of the wild-type promoter with C/EBP alpha or C/EBP be ta led to a decrease in promoter activity, which might in part explain the lack of activity of ADH7 in adult liver.