Retinoic acid regulation of one member of the human class I alcohol dehydrogenase (ADH) gene family was demonstrated, suggesting that the retinol dehydrogenase function of ADH may play a regulatory role in the biosynthetic pathway for retinoic acid. Promoter activity of human ADH3, but not ADHI or ADH2, was shown to be activated by retinoic acid in transient transfection assays of Hep3B human hepatoma cells. Deletion mapping experiments identified a region in the ADH3 promoter located between -328 and -272 bp which confers retinoic acid activation. This region was also demonstrated to confer retinoic acid responsiveness on the ADH1 and ADH2 genes in heterologous promoter fusions. Within a 34-bp stretch, the ADH3 retinoic acid response element (RARE) contains two TGACC motifs and one TGAAC motif, both of which exist in RAREs controiling other genes. A block mutation of the TGACC sequence located at -289 to -285 bp eliminated the retinoic acid response. As assayed by gel shift DNA binding studies, the RARE region (-328 to -272 bp) of ADH3 bound the human retinoic acid receptor , (RAR,3) and was competed for by DNA containing a RARE present in the gene encoding RARI. Since ADH catalyzes the conversion of retinol to retinal, which can be further converted to retinoic acid by aldehyde dehydrogenase, these results suggest that retinoic acid activation of ADH3 constitutes a positive feedback loop regulating retinoic acid synthesis.Retinoic acid has profound effects on vertebrate limb and nervous system morphogenesis as well as epithelial cell differentiation (12,31,40). The effects of retinoic acid are transduced by binding to a nuclear retinoic acid receptor (RAR) which, in the presence of ligand, is transformed into a transcription factor (6,14,28). Recently, a RAR gene family (RARa, -,B, and --y) has been discovered (3, 49), and differential expression of these receptors is undoubtedly important for correct transduction of the retinoic acid signal in various target tissues (9). There also exists another nuclear retinoic acid receptor, designated RXRc, which is not part of the RAR family and which is expressed highly in liver (23). Genes that respond to retinoic acid have been identified, and characterization of the retinoic acid response element (RARE) has been accomplished for genes encoding growth hormone (42), laminin Bi (45), RAR1 (7), and osteocalcin (33).One important aspect of retinoic acid-induced differentiation that is not understood is the mechanism regulating synthesis of retinoic acid from retinol (vitamin A). In mammals, retinol is reversibly oxidized to retinal by a cytosolic retinol dehydrogenase that is identical to class I alcohol dehydrogenase (ADH; EC 1.1.1.1), the enzyme which also functions as an ethanol dehydrogenase (21,22,26,29,44,48 tide subunits encoded by three closely related genes ADHI, ADH2, and ADH3, respectively (34). The substrate specificities of the various class I ADH isozymes (i.e., aa, 13, yy, a1, ay, and P-y) are very similar (43). Human ADH classes II and III are encoded by A...