C, are partly responsible for non-secretor status in a Caucasian population from Northern Portugal - PubMed (original) (raw)

Two new FUT2 (fucosyltransferase 2 gene) missense polymorphisms, 739G-->A and 839T-->C, are partly responsible for non-secretor status in a Caucasian population from Northern Portugal

Jacinta Serpa et al. Biochem J. 2004.

Abstract

Secretor status is defined by the expression of H type 1 antigen on gastric surface epithelium and external secretions. The H type 1 structure, and other fucosylated carbohydrates (Le(a), sialyl-Le(a), Le(b), Le(x), sialyl-Le(x) and Le(y)), can serve as ligands for several pathogens, including Helicobacter pylori, and are cancer-associated antigens. Secretor individuals are more susceptible to some bacterial and viral infections of the genito-urinary and digestive tracts. The aim of the present study was to examine FUT2 (fucosyltransferase 2 gene) polymorphisms in a Caucasian population of non-secretor individuals (n=36) from northern Portugal and to evaluate the activity of the mutant FUT2 enzymes. The secretor status was determined by UEAI [Ulex europaeus (gorse) lectin] histochemistry in gastric mucosa, and FUT2 polymorphisms were studied by restriction-fragment-length polymorphism and direct sequencing. The majority of non-secretors (88.9%) were homozygous for 428G-->A polymorphism; 5.6% were homozygous for 571C-->T and 5.6% were homozygous for two new missense polymorphisms, 739G-->A (2.8%) and 839T-->C (2.8%). By kinetic studies it was demonstrated that the two new FUT2 mutants (739G-->A and 839T-->C) are almost inactive and are responsible for some non-secretor cases.

PubMed Disclaimer

Figures

Figure 1. UEAI histochemistry and FUT2 genotype for 428G→A polymorphism in different individuals

(A) Negative for UEAI and homozygous for 428G→A; (B) negative for UEAI and normal for 428G→A; (C) positive for UEAI and normal for 428G→A; and (D) positive for UEAI and heterozygous for 428G→A. All images have the gastric surface on top.

Figure 2. Detection of FUT2 expression by RT-PCR

Expression of FUT2 and of GAPDH, used as an internal control, was detected by RT-PCR in Cos-7 cells either not transfected (Wt), mock transfected (mock) or transfected with variants of human FUT2 (FUT2 Wt, _FUT2_-739G_→_A and _FUT2_-839T_→_C).

Figure 3. Determination of apparent Michaelis–Menten constant (_K_m) and _V_max for GDP-fucose, phenyl β-D-galactoside and asialofetuin in FUT2 wt, FUT2-247Gly→Ser and FUT2-280Phe→Ser

(A) _K_m and _V_max for GDP-fucose in FUT2 wt; (B) _K_m and _V_max for GDP-fucose in FUT2-247Gly→Ser; (C) _K_m and _V_max for GDP-fucose in FUT2-280Phe→Ser; (D) _K_m and _V_max for phenyl β-

-galactoside in FUT2 wt; and (E) _K_m and _V_max for asialofetuin in FUT2 wt. The polymorphic enzymes FUT2-247Gly→Ser and FUT2-280Phe→Ser showed higher _K_m values and lower _V_max values for GDP-fucose compared with the FUT2 wt enzyme. It was not possible to calculate the _K_m and _V_max for phenyl β-

-galactoside and asialofetuin in FUT2-247Gly→Ser and FUT2-280Phe→Ser, since the reaction mixtures showed very low enzyme activity.

Figure 4. Transfer of GDP-fucose in different concentrations of acceptor and donor substrates for FUT2 wt, mock, FUT2-247Gly→Ser and FUT2-280Phe→Ser

(A) Incorporation of GDP-Fucose in different concentrations of cold GDP-fucose onto phenyl-β-

-galactoside; (B) incorporation of GDP-fucose in different concentrations of phenyl-β-

-galactoside, and (C) incorporation of GDP-fucose in different concentrations of asialofetuin. FUT2 wt enzyme showed high α-1,2-fucosyltransferase activity whereas FUT2-247Gly→Ser and FUT2-280Phe→Ser enzymes were very similar to mock.

References

1. Torrado J., Plummer M., Vivas J., Garay J., Lopez G., Peraza S., Carillo E., Oliver W., Muñoz N. Lewis antigen alterations in a population at high risk of stomach cancer. Cancer Epidemiol. Biomarkers Prev. 2000;9:671–674. - PubMed
1. Koda Y., Soejima M., Liu Y., Kimura H. Molecular basis for secretor type α(1,2)-fucosyltransferase gene deficiency in a Japanese population: a fusion gene generated by unequal crossover responsible for the enzyme deficiency. Am. J. Hum. Genet. 1996;59:343–350. - PMC - PubMed
1. Watkins W. M. Biochemistry and genetics of the ABO, Lewis and P blood group systems. Adv. Hum. Genet. 1980;10:1–136. - PubMed
1. Oriol R., Le Pendu J., Mollicone R. Genetics of ABO, H, Lewis, X and related antigens. Vox. Sang. 1986;51:161–171. - PubMed
1. Clausen H., Hakomori S. ABH and related histo-blood group antigens; immunochemical differences in carrier isotypes and their distribution. Vox. Sang. 1989;56:1–20. - PubMed

Two new FUT2 (fucosyltransferase 2 gene) missense polymorphisms, 739G-->A and 839T-->C, are partly responsible for non-secretor status in a Caucasian population from Northern Portugal - PubMed (original) (raw)