Mouse cytosolic class 3 aldehyde dehydrogenase (Aldh3a1): gene structure and regulation of constitutive and dioxin-inducible expression

The mouse cytosolic aldehyde dehydrogenase ALDH3A1 (encoded by the Aldh3a1 gene) has previously been shown in cell culture to be markedly inducible by 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD; dioxin), downregulated by the metabolism of functional CYP1A1/1A2 enzymes, and upregulated by a gene on C hr 7 that leads to endogenous oxidative stress, In order to study the regul ation of Aldh3a1 gene expression, we isolated two overlapping genomic seque nces from a B6/CBA mouse genomic library that included the entire Aldh3a1 g ene, along with considerable 5' and 3' flanking sequences, The Aldh3a1 gene was shown to span approximately 10 kb and comprise 11 exons including a no ncoding first exon, The sequence of 3.18 kb upstream of exon 1 reveals nume rous consensus transcription factor-binding sites, some of which were shown to be important in the positive and negative control of Aldh3a1 gene expre ssion; these include seven aromatic hydrocarbon response elements (AHREs), an electrophile response element (EPRE), and AP-1, C/EBP beta, c/EBP alpha, NF-kappa B, Sp1, and NF-1 putative binding sites, Deletion fusion construc ts containing regions of the Aldh3a1 gene 5' flanking sequence, ligated to chloramphenicol acetyltransferase (CAT) or luciferase (LUC) reporter genes, were studied, Transient transfection experiments suggested that the 5' fla nking region of the gene contains a strong promoter, at least four function al AHREs appear to act cooperatively in causing dioxin-mediated upregulatio n, and a putative negative regulatory element (NRE) controls basal gene exp ression independent of dioxin inducibility, The dioxin-mediated upregulatio n of Aldh3a1 expression in mouse hepatoma Hepa-1c1c7 cell cultures was show n to depend exclusively on the aromatic hydrocarbon receptor Pharmacogeneti cs 9:569-580 (C) 1999 Lippincott Williams & Wilkins.