Identification of a cis-acting element responsible for negative regulation of the human UDP-glucose dehydrogenase gene expression.

The enzyme UDP-glucose dehydrogenase (UGDH) catalyzes the conversion of UDP-glucose to UDP-glucuronic acid, which is essential for the biosynthesis of complex carbohydrates such as hyaluronan in many cell types, and is required for detoxification of toxic compounds in the liver. We previously defined the 714 bp 5'-flanking region of the UGDH gene as the core promoter, with putative negative regulatory elements residing in the region upstream of it. In the present study, we delineated the region from nucleotide positions -1057 to -957 on the UGDH promoter to be responsible for the repression of promoter activity. A mutation at nucleotide -1003, which is contained within a motif predicted to be the response element for peroxisome proliferator receptor alpha (PPARalpha), abolished the suppression effect. DNA-protein interaction was observed at this motif by electrophoretic mobility shift assay. The proteins interacting with the PPRE-like repressor motif were purified by biotin-labeled DNA affinity chromatography. Subsequently, MALDI-TOF identified the purified proteins as a 62-kDa zinc finger and a 42-kDa beta-actin protein. Hence in this study we report the presence of an inhibitory cis-element in the distal region of the UGDH promoter that interacts with putative transcriptional repressors for the negative regulation of the UGDH gene.