title: Functional heterogeneity of colonic adenocarcinoma mucins for inhibition of Entamoeba histolytica adherence to target cells.
abstract: Mucins secreted from the gastrointestinal epithelium from the basis of the adherent mucus layer which is the host's first line of defense against invasion by Entamoeba histolytica. Galactose and N-acetyl-D-galactosamine residues of mucins specifically inhibit binding of the amebic 170 kDa heavy subunit Gal-lectin to target cells, an absolute prerequisite for pathogenesis. Herein we characterized the secretory mucins isolated from the human colon and from three human colonic adenocarcinoma cell lines: two with goblet cell-like (LS174T and T84) and one with absorptive cell-like morphology (Caco-2). By Northern blot analysis the intestinal mucin genes MUC2 and MUC3 were constitutively expressed by confluent LS174T and Caco-2 cells, whereas T84 cells only transcribed MUC2 and not MUC3 mRNA. 3H-glucosamine and 3H-threonine metabolically labeled proteins separated as high M, mucins in the void (Vo > 10(6) Da) of Sepharose-4B column chromatography and remained in the stacking gel of SDS-PAGE as depicted by fluorography. All mucin preparations contained high amounts of N-acetyl-glucosamine, galactose, N-acetyl-galactosamine, fucose and sialic acid, saccharides typical of the O-linked carbohydrate side chains. Mucin samples from the human colon and from LS174T and Caco-2 cells inhibited E. histolytica adherence to chinese hamster ovary cells, whereas mucins from T84 cells did not. These results suggest that genetic heterogeneity and/or posttranslational modification in glycosylation of colonic mucins can affect specific epithelial barrier function against intestinal pathogens.
authors.affiliation: Institute of Parasitology, McGill University, Québec, Canada.
authors.forename: M U
authors.initials: MU
authors.lastname: Göttke
authors.forename: K
authors.initials: K
authors.lastname: Keller
authors.forename: A
authors.initials: A
authors.lastname: Belley
authors.forename: R M
authors.initials: RM
authors.lastname: Garcia
authors.forename: M A
authors.initials: MA
authors.lastname: Hollingsworth
authors.forename: D R
authors.initials: DR
authors.lastname: Mack
authors.forename: K
authors.initials: K
authors.lastname: Chadee
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000737:chemistry* / Q000503:physiopathology; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015152:Blotting, Northern; D016466:CHO Cells; D018938:Caco-2 Cells; D015815:Cell Adhesion Molecules / Q000737:chemistry*; D002847:Chromatography, Agarose; D002849:Chromatography, Gas; D003106:Colon / Q000737:chemistry*; D003110:Colonic Neoplasms / Q000737:chemistry*; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D004748:Entamoeba histolytica / Q000737:chemistry*; D004749:Entamoebiasis / Q000469:parasitology; D005470:Fluorometry; D015972:Gene Expression Regulation, Neoplastic; D006790:Host-Parasite Interactions / Q000502:physiology; D006801:Humans; D009077:Mucins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D014407:Tumor Cells, Cultured
chemical_list: D000596:Amino Acids; D015815:Cell Adhesion Molecules; D009077:Mucins; D012333:RNA, Messenger