title: The C-type lectin L-SIGN differentially recognizes glycan antigens on egg glycosphingolipids and soluble egg glycoproteins from Schistosoma mansoni.
abstract: Recognition of pathogen-derived carbohydrate constituents by antigen presenting cells is an important step in the induction of protective immunity. Here we investigated the interaction of L-SIGN (liver/lymph node specific ICAM-3-grabbing nonintegrin), a C-type lectin that functions as antigen receptor on human liver sinusoidal endothelial cells, with egg-derived glycan antigens of the parasitic trematode Schistosoma mansoni. Our data demonstrate that L-SIGN binds both schistosomal soluble egg antigens (SEA) and egg glycosphingolipids, and can mediate internalization of SEA by L-SIGN expressing cells. Binding and internalization of SEA was strongly reduced after treatment of SEA with endoglycosidase H, whereas defucosylation affected neither binding nor internalization. These data indicate that L-SIGN predominantly interacts with oligomannosidic N-glycans of SEA. In contrast, binding to egg glycosphingolipids was completely abolished after defucosylation. Our data show that L-SIGN binds to a glycosphingolipid fraction containing fucosylated species with compositions of Hex(1)HexNAc(5-7)dHex(3-6)Cer, as evidenced by mass spectrometry. The L-SIGN "gain of function" mutant Ser363Val, which binds fucosylated Lewis antigens, did not bind to this fucosylated egg glycosphingolipid fraction, suggesting that L-SIGN displays different modes in binding fucoses of egg glycosphingolipids and Lewis antigens, respectively. Molecular modeling studies indicate that the preferred binding mode of L-SIGN to the respective fucosylated egg glycosphingolipid oligosaccharides involves a Fucalpha1-3GalNAcbeta1-4(Fucalpha1-3)GlcNAc tetrasaccharide at the nonreducing end. In conclusion, our data indicate that L-SIGN recognizes both oligomannosidic N-glycans and multiply fucosylated carbohydrate motifs within Schistosoma egg antigens, which demonstrates that L-SIGN has a broad but specific glycan recognition profile.
authors.affiliation: Institute of Biochemistry, Medical Faculty, Justus-Liebig-University Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Meyer
authors.forename: Boris
authors.initials: B
authors.lastname: Tefsen
authors.forename: Anne
authors.initials: A
authors.lastname: Imberty
authors.forename: Rudolf
authors.initials: R
authors.lastname: Geyer
authors.forename: Irma
authors.initials: I
authors.lastname: van Die
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology / Q000378:metabolism*; D002240:Carbohydrate Sequence; D002448:Cell Adhesion / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005643:Fucose / Q000378:metabolism; D006023:Glycoproteins / Q000276:immunology / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000494:pharmacology; D006028:Glycosphingolipids / Q000276:immunology / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D020014:K562 Cells; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010063:Ovum / Q000276:immunology*; D011134:Polysaccharides / Q000276:immunology / Q000378:metabolism*; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012550:Schistosoma mansoni / Q000276:immunology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000947:Antigens, Helminth; C433029:CLEC4M protein, human; D015815:Cell Adhesion Molecules; D006023:Glycoproteins; D006028:Glycosphingolipids; D037181:Lectins, C-Type; D011134:Polysaccharides; D011956:Receptors, Cell Surface; D005643:Fucose; D006026:Glycoside Hydrolases