Dectin-1: a signalling non-TLR pattern-recognition receptor

Dectin-1 is a mainly myeloid-cell-expressed NK-cell-receptor-like C-type lectin that functions as a transmembrane pattern-recognition receptor through its ability to bind β-glucan carbohydrates. Dectin-1 also recognizes an unidentified endogenous ligand on T cells, possibly acting as a co-stimulatory molecule.Following ligand binding, dectin-1 can mediate various cellular responses, including cytokine and chemokine production, the respiratory burst and phagocytosis.Cellular responses are mediated by signalling events initiated from the atypical cytoplasmic immunoreceptor tyrosine-based activation motif of dectin-1 using novel pathways, including the protein spleen tyrosine kinase (SYK) and collaborative signalling with the Toll-like receptors, in a cell-specific manner.Dectin-1 can recognize several fungal pathogens and might play a role in the innate response to these organisms. These pathogens, in turn, might have mechanisms for avoiding recognition by this receptor.Dectin-1 is likely to play a role in the protective effects against infectious and non-infectious diseases exerted by purified soluble β-glucans in vivo, although the mechanisms behind these activities are unclear.On certain genetic backgrounds, dectin-1 can play a central role in the development of β-glucan-induced autoimmune disease and might also contribute to the development of fungal-induced respiratory disorders.The activities of dectin-1 might be representative of other pattern-recognition receptors, especially other myeloid-cell-expressed NK-cell-receptor-like C-type lectins, which have similar signalling motifs in their cytoplasmic tails.