Mouse Microsomal Class 3 Aldehyde Dehydrogenase: AHD3 cDNA Sequence, Inducibility by Dioxin and Clofibrate, and Genetic Mapping

摘要

ABSTRACTWe have cloned and sequenced the mouse AHD3 cDNA, which codes for the Class 3 microsomal aldehyde dehydrogenase (ALDH3m). The cDNA is 2,997 bp in length excluding the poly(A)+tail, and has 5′ and 3′ nontranslated regions of 113 bp and 1,429 bp, respectively. The deduced amino acid sequence consists of 484 amino acids, including the first methionine (Mr= 53,942), and contains a hydrophobic segment at the carboxyl terminus which is the putative membrane anchor. The mouse AHD3 protein was found to be: 95 similar to the rat microsomal ALDH3m protein, 65 identical to the mouse, rat and human cytosolic ALDH3c protein, and<28 similar to the rat Class 1 and Class 2 ALDH and methylmalonate-semialdehyde dehydrogenase proteins. Southern hybridization analysis of mouse cDNA probed with the full-length AHD3 cDNA revealed that theAhd3gene likely spans less than a total of 25 kb. The mouseAhd3gene is very tightly linked to theAhd4gene on chromosome 11. Mouse AHD3 mRNA levels are increased by dioxin in mouse Hepa-1c1c7 hepatoma wild-type (wt) cells but not in the Ah receptor nuclear translocator (ARNT)-defective (c4) mutant line, indicating that the induction process is mediated by the Ah (aromatichydrocarbon) dioxin-binding receptor. AHD3 mRNA levels are also inducible by clofibrate in both the wt andc4lines. AHD3 mRNA levels are not elevated in the CYP1A1 metabolism-deficientc37mutant line or as part of the oxidative stress response found in the untreated14CoS/14CoSmouse cell line. These data indicate that, although inducible by dioxin, theAhd3gene does not qualify as a member of thearomaticAydrocarbon Ah gene batt