Characterization of the promoter region of the human peroxisomal multifunctional enzyme type 2 gene

Peroxisomal multifunctional enzyme type 2 (perMFE-8) catalyzes conversion o f (24E)-3 alpha ,7 alpha, 12 alpha -trihydroxy-5 beta -cholest-24-enoyl-CoA to (24-keto)-3 alpha ,7 alpha ,12 alpha -trihydroxy-5 beta -cholestanoyl-C oA, which are physiological intermediates in cholic acid synthesis. In cont rast to long chain fatty acid oxidizing enzymes clofibrate does not induce peroxisomal enzymes metabolizing bile acid intermediates. We proposed the e xistence of PPAR-independent regulation of cholesterol side chain oxidation in the process of bile acid synthesis. In the present study, we characteri zed the promoter region of the human perMFE-2 gene. The promoter contains t he Sp1/AP2 binding site (-151/-142) within 197 base pairs upstream of the t ranslation start site. Mutation of the Sp1/AP2 binding site decreases the p romoter activity. Analysis by the luciferase assay revealed that the activi ty of the promoter region is strong in HepGr2 and HeLa cell lines, although the activity in HepG2 cells was five- to sixfold higher than that in HeLa cells. Transient transfection assays have confirmed that AP2 alpha and AP2 gamma were able to transactivate the perMFE-2 promoter/luciferase chimeric gene. Cotransfections with Spl expression plasmid decreased the promoter ac tivity. We suggest that perMFE-2 promoter activity is the result of both th e abundance of AP2 and Spl family members and their relative ratios. (C) 20 01 Academic Press.