In fucosyltransferase genes, mRNA expression is regulated in a cell-type-specific manner. The expression level of human fucosyltransferase 4 (FUT4) mRNA is high in both colon adenocarcinoma and myeloid cell lines. We will demonstrate here cell-specific expression and transcriptional regulation of the FUT4 gene. FUT4 has two different transcription initiation sites that respectively produce long- and short-form mRNAs. To determine the major FUT4 transcript in colon adenocarcinoma and myeloid cell lines, we analyzed the transcriptional starting sites of the FUT4 gene in myeloid and colon adenocarcinoma cell lines, using 5'-RACE, RT-PCR, and luciferase analysis. The results suggested that the expression level of short-form mRNA is higher than the long-form transcript in the colon adenocarcinoma cell lines and that the expression level of long-form mRNA is higher than the short-form transcript in the myeloid cell lines. Using a luciferase assay, we identified a functional DNA portion within FUT4 genomic DNA that confers a colon adenocarcinoma cell line-specific enhancer, located in nucleotide number (nt) -256 to -44, and a myeloid cell line-specific enhancer, located in nt -686 to -582. The present results suggest that these elements play a critical role in the colon adenocarcinoma and leukemia cell-specific transcriptional regulation of the FUT4 gene.
Copyright 2000 Academic Press.