CELL-SPECIFIC FUNCTION OF CIS-ACTING ELEMENTS IN THE REGULATION OF HUMAN ALCOHOL-DEHYDROGENASE-5 GENE-EXPRESSION AND EFFECT OF THE 5'-NONTRANSLATED REGION

The human alcohol dehydrogenase 5 gene (ADH5) differs from all other h uman alcohol dehydrogenase genes in its ubiquitous expression, althoug h there are tissue-specific differences in the level of expression, To under stand the expression of ADH5, we characterized the structure an d function of its 5' region by DNase I footprinting and transient tran sfection assays. The region from base pair (bp) -34 to +61, flanking t he major transcription start site, had strong promoter activity in thr ee different cell lines: HeLa, H4IIE-C3, and CV-1, and could explain t he ubiquitous expression, Two Sp1 sites within that region are footpri nted by nuclear extracts from all tissues and cells tested. There are sites further upstream that show cell- and tissue-specific differences in both their patterns of occupancy and their effects on promoter act ivity. The region between bp -34 and -64 strongly increases promoter a ctivity in H4IIE-C3 cells, weakly activates in CV-1 cells, but has no effect in HeLa cells. The region between bp -127 and -163 is a positiv e element in both HeLa cells and CV-1 cells, but is a negative regulat ory element in H4IIE-C3 cells. These differences in part explain the l evels of expression of ADH5 in various tissues. Two regions (bp -64 to -127 and bp -163 to -365) contain negative regulatory elements that r educe promoter activity in all three cells. The 5'-nontranslated regio n of ADH5 contains two upstream ATGs. Insertion of 12 bp within the pu tative coding region of these upstream ATGs led to a 1.6-2.3-fold incr ease in activity. This suggests that the 5'-nontranslated region has r egulatory significance.