Ligands for the beta-glucan receptor, Dectin-1, assigned using "designer" microarrays of oligosaccharide probes (neoglycolipids) generated from glucan polysaccharides.
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.
Palma
Angelina S
AS
Glycosciences Laboratory, Faculty of Medicine, Imperial College London, Northwick Park and St Mark's Campus, Watford Road, Harrow, Middlesex HA1 3UJ, United Kingdom.
Feizi
Ten
T
Zhang
Yibing
Y
Stoll
Mark S
MS
Lawson
Alexander M
AM
Díaz-Rodríguez
Esther
E
Campanero-Rhodes
María Asunción
MA
Costa
Júlia
J
Gordon
Siamon
S
Brown
Gordon D
GD
Chai
Wengang
W
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
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