Epithelial-cell-specific transcriptional regulation of human Galbeta1,3GalNAc/Galbeta1,4GlcNAc alpha2,3-sialyltransferase (hST3Gal IV) gene.

The mRNA expression of the sialyltransferase genes is regulated in a cell type specific manner. We show here the epithelium cell-specific transcriptional regulation of the human Galbeta1, 3GalNAc/Galbeta1, 4 GlcNAc alpha2,3-sialyltransferase gene (hST3Gal IV). Using a luciferase assay, we identified a functional DNA portion within hST3Gal IV genomic DNA that confers an epithelial cell line specific enhancer, located in nucleotide number (nt) -520 to -420 within the B3 promoter. This element contains two sequences similar to AP2 recognition motifs. Co-transfection with an AP2 expression vector stimulated the enhancer activity of nt -520 to -420 element eight-fold compared with that using parental vector. Site-directed mutagenesis of AP2 sites showed that two AP2 motifs are essential for enhancer activity in HeLa cells. These results suggest that AP2 plays a critical role in the epithelium-cell specific transcriptional regulation of the hST3Gal IV gene.