Functional analysis of the 5 '-flanking region of FTA for expression of rat GDP-L-fucose :beta-D-galactoside 2-alpha-L-fucosyltransferase

The tissue-specific and species-specific expression of the ABH antigens is well known among vertebrate species and it is regulated by the alpha(1,2)fu cosyltransferase that forms the H antigen, a precursor of the A and B antig ens. To investigate the mechanisms governing the tissue-specific and specie s-specific expression of this alpha(1,2)fucosyltransferase, we characterize d the gene structure, including the promoter region, of FTA, a rat ortholog ous homolog of human FUT1 that encodes the H alpha(1,2)fucosyltransferase a nd is responsible for the expression of the ABH antigens on human red blood cells. Northern blot and 5'-RACE analyses suggested that at least two form s of FTA mRNA (2.9 and 2.6 kb), which use alternative transcription start s ites, are present in the cancer cell lines RCN-9 (rat colon cancer) and PC1 2 (rat pheochromocytoma), whereas only the 2.6 kb form was detected in norm al colon, stomach and pancreas. Transcriptional activity of the 5'-flanking sequence, which contains three putative Spl-binding sites, but lacks both TATA and CAAT boxes, was examined. Transient transfection experiments of pr omoter-reporter gene constructs showed high promoter activity in RCN-9, PC1 2 and human colon cancer (WiDr) cell lines, weak activity in human vascular endothelial (ECV304) cells and no activity in human erythroleukemia (HEL) cells. The results suggest that the 5'-flanking region of FTA contains a ti ssue-specific promoter. Deletional analysis of the 5'-flanking sequence rev ealed regions containing cell-type specific positive acting element(s) and negative regulatory element(s), which are related to the promoter activity.