Glycobiology Advance Access originally published online on June 15, 2005
Glycobiology 2005 15(10):1002-1007; doi:10.1093/glycob/cwi089
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Gastrointestinal mucins of Fut2-null mice lack terminal fucosylation without affecting colonization by Candida albicans
2 Department of Obstetrics and Gynecology, Cellular and Molecular Biology Program, 6428 Medical Science I Box 0617, University of Michigan Medical Center, Ann Arbor, MI 48109-0617; and 3 Department of Medical Biochemistry, Göteborg University, Medicinaregatan 9A, 413 90 Gothenburg, Sweden
1 To whom correspondence should be addressed; e-mail: sedomino{at}med.umich.edu
Received on March 22, 2005; revised on April 28, 2005; accepted on June 3, 2005
Posttranslational modification of apomucins by the sequential action of glycosyltransferases is required to produce mature mucins. The Secretor gene (FUT2) encodes an
Key words:
fucosyltransferase
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mucin
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O-glycosylation
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Secretor gene
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yeast
(1,2)fucosyltransferase (EC 2.4.1.69(1,2)fucose residues on mucins and other molecules in mucosal epithelium. Mutant mice containing targeted replacement of Fut2 with the bacterial reporter gene lacZ were studied to determine the affect of the loss of Fut2 on glycosylation of mucins in the gastrointestinal tract. By whole organ X-gal staining, lacZ activity is prominently expressed in the foveolar pit and chief cells of the glandular stomach, Brunner’s glands of the duodenum, and goblet cells in the large intestine of Fut2-LacZ-null mice. Staining with Aleuria aurantia agglutinin demonstrates loss of L-fucosylated epithelial glycans throughout the gastrointestinal tract of Fut2-LacZ-null mice, however, histologic appearance of the tissues appears normal. Analysis of oligosaccharides released from insoluble colonic mucins, largely Muc2, by mass spectrometry shows complete lack of terminal fucosylation of O-linked oligosaccharides in Fut2-LacZ-null mice. Precursor glycans accumulate with no evidence of compensation by other fucosyltransferases or sialyltransferases on mucin glycosylation. Because Candida albicans has been reported to adhere to intestinal mucins creating a potential reservoir associated with vaginitis, Fut2-LacZ-null and wild-type mice were inoculated by gastric lavage with C. albicans. We observe no difference in colonization between genotypes suggesting mucin terminal fucosylation does not significantly influence C. albicans–host interaction in the intestine, highlighting that infections caused by the same organism at different mucosal surfaces are not equal.