title: Ligands for the beta-glucan receptor, Dectin-1, assigned using "designer" microarrays of oligosaccharide probes (neoglycolipids) generated from glucan polysaccharides.
abstract: Dectin-1 is a C-type lectin-like receptor on leukocytes that mediates phagocytosis and inflammatory mediator production in innate immunity to fungal pathogens. Dectin-1 lacks residues involved in calcium ligation that mediates carbohydrate-binding by classical C-type lectins; nevertheless, it binds zymosan, a particulate beta-glucan-rich extract of Saccharomyces cerevisiae, and binding is inhibited by polysaccharides rich in beta1,3- or both beta1,3- and beta1,6-linked glucose. The oligosaccharide ligands on glucans recognized by Dectin-1 have not yet been delineated precisely. It is also not known whether Dectin-1 can interact with other types of carbohydrates. We have investigated this, since Dectin-1 shows glucan-independent binding to a subset of T-lymphocytes and is involved in triggering their proliferation. Here we assign oligosaccharide ligands for Dectin-1 using the neoglycolipid-based oligosaccharide microarray technology, a unique approach for constructing microarrays of lipid-linked oligosaccharide probes from desired sources. We generate "designer" microarrays from three glucan polysaccharides, a neutral soluble glucan isolated from S. cerevisiae and two bacterial glucans, curdlan from Alcaligenes faecalis and pustulan from Umbilicaria papullosa, and use these in conjunction with 187 diverse, sequence-defined, predominantly mammalian-type, oligosaccharide probes. Among these, Dectin-1 binding is detected exclusively to 1,3-linked glucose oligomers, the minimum length required for detectable binding being a 10- or 11-mer. Thus, the ligands assigned so far are exogenous rather than endogenous. We further show that Dectin-1 ligands, 11-13 gluco-oligomers, in clustered form (displayed on liposomes), mimic the macromolecular beta-glucans and compete with zymosan binding and triggering of tumor necrosis factor-alpha secretion by a Dectin-1-expressing macrophage cell line.
authors.affiliation: Glycosciences Laboratory, Faculty of Medicine, Imperial College London, Northwick Park and St Mark's Campus, Watford Road, Harrow, Middlesex HA1 3UJ, United Kingdom.
authors.forename: Angelina S
authors.initials: AS
authors.lastname: Palma
authors.forename: Ten
authors.initials: T
authors.lastname: Feizi
authors.forename: Yibing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Mark S
authors.initials: MS
authors.lastname: Stoll
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Lawson
authors.forename: Esther
authors.initials: E
authors.lastname: Díaz-Rodríguez
authors.forename: María Asunción
authors.initials: MA
authors.lastname: Campanero-Rhodes
authors.forename: Júlia
authors.initials: J
authors.lastname: Costa
authors.forename: Siamon
authors.initials: S
authors.lastname: Gordon
authors.forename: Gordon D
authors.initials: GD
authors.lastname: Brown
authors.forename: Wengang
authors.initials: W
authors.lastname: Chai
mesh_terms: D000818:Animals; D002460:Cell Line; D006017:Glycolipids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D037181:Lectins, C-Type; D008024:Ligands; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D015345:Oligonucleotide Probes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism; D047071:beta-Glucans / Q000737:chemistry / Q000378:metabolism*; D000099181:Dectin-1
chemical_list: D006017:Glycolipids; D037181:Lectins, C-Type; D008024:Ligands; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D015345:Oligonucleotide Probes; D011134:Polysaccharides; D011993:Recombinant Fusion Proteins; D047071:beta-Glucans; D000099181:Dectin-1