title: Ligand binding and signaling of dendritic cell immunoreceptor (DCIR) is modulated by the glycosylation of the carbohydrate recognition domain.
abstract: C-type lectins are innate receptors expressed on antigen-presenting cells that are involved in the recognition of glycosylated pathogens and self-glycoproteins. Upon ligand binding, internalization and/or signaling often occur. Little is known on the glycan specificity and ligands of the Dendritic Cell Immunoreceptor (DCIR), the only classical C-type lectin that contains an intracellular immunoreceptor tyrosine-based inhibitory motif (ITIM). Here we show that purified DCIR binds the glycan structures Lewis(b) and Man3. Interestingly, binding could not be detected when DCIR was expressed on cells. Since DCIR has an N-glycosylation site inside its carbohydrate recognition domain (CRD), we investigated the effect of this glycan in ligand recognition. Removing or truncating the glycans present on purified DCIR increased the affinity for DCIR-binding glycans. Nevertheless, altering the glycosylation status of the DCIR expressing cell or mutating the N-glycosylation site of DCIR itself did not increase glycan binding. In contrast, cis and trans interactions with glycans induced DCIR mediated signaling, resulting in a decreased phosphorylation of the ITIM sequence. These results show that glycan binding to DCIR is influenced by the glycosylation of the CRD region in DCIR and that interaction with its ligands result in signaling via its ITIM motif.
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Karien
authors.initials: K
authors.lastname: Bloem
authors.forename: Ilona M
authors.initials: IM
authors.lastname: Vuist
authors.forename: Arend-Jan
authors.initials: AJ
authors.lastname: van der Plas
authors.forename: Léon M J
authors.initials: LM
authors.lastname: Knippels
authors.forename: Johan
authors.initials: J
authors.lastname: Garssen
authors.forename: Juan J
authors.initials: JJ
authors.lastname: García-Vallejo
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: van Vliet
authors.forename: Yvette
authors.initials: Y
authors.lastname: van Kooyk
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D003412:Cricetulus; D005434:Flow Cytometry; D006801:Humans; D047468:Immunoprecipitation; D037181:Lectins, C-Type / Q000737:chemistry* / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D011485:Protein Binding; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: C423004:CLEC4A protein, human; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D011134:Polysaccharides; D011971:Receptors, Immunologic