Structural diversity and specific distribution of O-glycans in normal human mucins along the intestinal tract.
Purified human mucins from different parts of the intestinal tract (ileum, cecum, transverse and sigmoid colon and rectum) were isolated from two individuals with blood group ALe(b) (A-Lewis(b)). After alkaline borohydride treatment the released oligosaccharides were structurally characterized by nano-ESI Q-TOF MS/MS (electrospray ionization quadrupole time-of-flight tandem MS) without prior fractionation or derivatization. More than 100 different oligosaccharides, with up to ten monosaccharide residues, were identified using this technique. Oligosaccharides based on core 3 structures, GlcNAc(beta1-3)GalNAc (where GlcNAc is N-acetyl-D-glucosamine and GalNAc is N-acetylgalactosamine), were widely distributed in human intestinal mucins. Core 5 structures, GalNAc(alpha1-3)GalNAc, were also recovered in all fractions. Moreover, a comparison of the oligosaccharide repertoire, with respect to size, diversity and expression of glycans and terminal epitopes, showed a high level of mucin-specific glycosylation: highly fucosylated glycans, found specifically in the small intestine, were mainly based on core 4 structures, GlcNAc-(beta1-3)[GlcNAc(beta1-6)]GalNAc, whereas the sulpho-Le(X) determinant carrying core 2 glycans, Gal(beta1-3)[GlcNAc(beta1-6)]-GalNAc (where Gal is galactose), was recovered mainly in the distal colon. Blood group H and A antigenic determinants were present exclusively in the ileum and cecum, whereas blood group Sd(a)/Cad related epitopes, GalNAc(beta1-4)[NeuAc(alpha2-3)]Gal (where NeuAc is N-acetylneuraminate), were found to increase along the length of the colon. Our findings suggest that mucins create an enormous repertoire of potential binding sites for micro-organisms that could explain the regio-specific colonization of bacteria in the human intestinal tract.
Robbe
Catherine
C
Unité Mixte de Recherche CNRS/USTL 8576, Glycobiologie Structurale et Fonctionnelle, IFR 118, Université des Sciences et Technologies de Lille 1, 59655 Villeneuve d'Ascq Cedex, France.
Capon
Calliope
C
Coddeville
Bernadette
B
Michalski
Jean-Claude
JC
D002102:Cadaver; D002240:Carbohydrate Sequence; D005591:Chemical Fractionation / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003106:Colon / Q000737:chemistry; D005643:Fucose / Q000378:metabolism; D006801:Humans; D007422:Intestines / Q000737:chemistry*; D016030:Kidney Transplantation; D007983:Lewis Blood Group Antigens / Q000737:chemistry; D008297:Male; D009077:Mucins / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D009438:Neuraminic Acids / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013463:Sulfuric Acid Esters / Q000378:metabolism; D014019:Tissue Donors
D007983:Lewis Blood Group Antigens; D009077:Mucins; D009438:Neuraminic Acids; D011134:Polysaccharides; D013463:Sulfuric Acid Esters; D005643:Fucose