Structure and Expression of the Gene Encoding Secretor‐Type Galactoside 2‐α‐l‐fucosyltransferase (FUT2)

Abstract

The expression and secretion of ABO antigens in epithelial cells of glands are controlled by secretortype a(l,2)fucosyltransferase activity. We have examined the expression of the secretor-type a( 1,2)fucosyltransferase gene (FUT2) and a pseudogene of FUT2 (Secl) in several tumor cell lines by northern blot and/or reverse-transcription-PCR (RT-PCR) analyses. Transcripts of FUT2 were found in total RNA from ovarian, gastric and colonic cancer cell lines but not from six leukemic cell lines, including erythroleukemic HEL cells, by RT-PCR. On the other hand, RT-PCR indicated that Secl was expressed in all these tumor cells, including all hematopoietic cells studied. Northern blot analysis indicated that FUT2 transcripts with a similar size (3.3 kb) were expressed in cancer cell lines. Rapid amplification of cDNA ends suggested that the entire FUT2 cDNA is 3.1-kb long and has two Alu repetitive elements in its 3' untranslated region, including an inverted repeat. The mRNA, therefore, may form a large stem-and-loop structure (1.2 kb). Each stem contains about 300 bases, the loop contains 640 bases, and the percentage of complementary nucleotide sequences in the stem region is 85%. The presence of a large stem-andloop structure in the 3' untranslated region may regulate the level of the FUT2 transcript by affecting the stability of the mRNA.

Evolutionarily Conserved, “Acatalytic” Carbonic Anhydrase-Related Protein XI Contains a Sequence Motif Present in the Neuropeptide Sauvagine: The Human CA-RP XI Gene (CA11) Is Embedded between theSecretorGene Cluster and theDBPGene at 19q13.3

“…(CA11) is not yet known, the final intron is labeled N and the final exon Nϩ1. Seventy-five basepairs of the CA11 antisense strand are identical to the first 75 bp of the ovarian cancer cell Sec1 transcripts (Koda et al, 1997) from the FUT2P gene. FUT2P is a pseudogene, not expressed in normal tissues examined by Koda et al (1997).…”

“…Seventy-five basepairs of the CA11 antisense strand are identical to the first 75 bp of the ovarian cancer cell Sec1 transcripts (Koda et al, 1997) from the FUT2P gene. FUT2P is a pseudogene, not expressed in normal tissues examined by Koda et al (1997). It is homologous to, and part of, a cluster containing the FUT2 and FUT1 genes, which encode the Secretor and H blood groups, respectively (Kelly et al, 1995; GenBank U17895; OMIM 182100).…”

“…Thus, CA11 and DBP appear to be head-to-tail genes transcribed in the same orientation. Either the Sec1 pseudogene is contained within the final intron of the CA11 gene or, more likely, CA11 is contained entirely within intron 1 of the Sec1 transcripts, which do not appear to be expressed in normal tissues (Koda et al, 1997). Thus, in ovarian cancer cells, an unusual promoter at the 3Ј end of CA11 is used, and a donor splice site is encountered after 75 bp; the acceptor splice site is presumed to be 5Ј of CA11 (see Fig.…”

An Alu -mediated large deletion of the FUT2 gene in individuals with the ABO-Bombay phenotype

“…In addition, we have determined the gene structure of FUT2 (Koda et al 1997a). The results indicate that FUT2 consists of two exons that are separated by a 7-kb intron sequence.…”

The Fusion Gene at the ABO-Secretor Locus (FUT2): absence in Chinese populations

“…Secretors, who have ABO antigens in saliva, have at least one functional Se allele, and nonsecretors, who fail to express ABO antigens in saliva, are homozygous for the nonfunctional se allele. After the isolation of cDNA and genomic DNA of the FUT2 gene (Kelly et al 1995;Koda et al 1997a), molecular analysis of FUT2 has indicated that null alleles with a single base substitution in the protein coding region of FUT2 (G428A, A385T, C571T, C628T and G849A) were responsible for the inactivation of Se enzyme (Kelly et al 1995;Yu et al 1996;Koda et al 1996). The findings from these studies suggested that these null alleles were geographic-specific and perhaps therefore race-specific.…”