title: Core saccharide dependence of sialyl Lewis X biosynthesis.
abstract: The sialyl-Lewis X (SLe(x)) determinant is important in leukocyte extravasation, metastasis and bacterial adhesion. The role of the protein, N-glycan and O-glycan core structures for the biosynthesis of SLe(x) in vivo by fucosyltransferases (FucTs) is not known. Immunoglobulin G (IgG) Fc fusion proteins of alpha(1)-acid glycoprotein (AGP), P-selectin glycoprotein ligand-1 (PSGL-1) or CD43 were used to probe the specificity of FucT-III-VII expressed alone in 293T and COS cells or together with O-glycan core enzymes in Chinese hamster ovary (CHO)-K1 cells. Western blotting with the monoclonal antibodies CSLEX and KM93 showed that FucT-III and V-VII produced SLe(x) on core 2 in CHO cells. Only FucT-V, -VI and, with low activity, -VII worked on core 3 on CD43/IgG, but no SLe(x) was detected with CSLEX on PSGL-1/IgG with core 3. KM93 stained SLe(x) on core 2, but was not reactive with SLe(x) on core 3. FucT-III, V-VII made SLe(x) on N-glycans of AGP/IgG in CHO, but not in COS and 293T cells, even though the same FucTs could make SLe(x) on CD43/IgG and PSGL-1/IgG in these cells. Our results define the specificities of FucT-III-VII in SLe(x) biosynthesis on O-glycans with different core structures and the fine specificity of the widely used anti-SLe(x) monoclonal antibody, KM93.
authors.affiliation: Division of Clinical Immunology and Transfusion Medicine, F79, Karolinska Institute, Karolinska University Hospital, Huddinge, 141 86 Stockholm, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Löfling
authors.forename: Jan
authors.initials: J
authors.lastname: Holgersson
mesh_terms: D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D005647:Fucosyltransferases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000235:genetics; D011134:Polysaccharides / Q000096:biosynthesis* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000080506:Sialyl Lewis X Antigen; D013379:Substrate Specificity / Q000502:physiology
chemical_list: D009844:Oligosaccharides; D011134:Polysaccharides; D011993:Recombinant Fusion Proteins; D000080506:Sialyl Lewis X Antigen; D005647:Fucosyltransferases