title: Molecular characterization of a transmembrane C-type lectin receptor gene from ayu (Plecoglossus altivelis) and its effect on the recognition of different bacteria by monocytes/macrophages.
abstract: C-type lectin receptors (CTLRs) play vital roles in immune responses as pattern-recognition receptors (PRRs). In this study, we identified a novel C-type lectin receptor (PaCTLRC) gene from ayu, Plecoglossus altivelis. Predicted PaCTLRC is a single transmembrane receptor with a typical carbohydrate recognition domain (CRD) at its C-terminus. Sequence comparison and phylogenetic tree analysis showed that PaCTLRC was most closely related to Atlantic salmon (Salmo salar) CLRC, but was significantly different from two other ayu CTLRs, aCLR and PaCD209L. PaCTLRC transcript was detected in all tested tissues and cells, with high levels in the liver; and its expression was significantly altered upon Vibrio anguillarum infection. Refolded recombinant PaCTLRC (rPaCTLRC) agglutinated three types of Gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus and Streptococcus iniae) and four types of Gram-negative bacteria (Aeromonas hydrophila, Escherichia coli, V. anguillarum and Vibrio parahaemolyticus) in a Ca(2+)-dependent manner in vitro, and Gram-positive bacteria were shown to be biologically relevant ligands for PaCTLRC. rPaCTLRC bound to d-mannose, d-galactose, l-fucose, N-acetyl-d-glucosamine (GlcNAc), lipopolysaccharide (LPS) and peptidoglycan (PGN), exhibiting a relative binding strength to d-mannose and PGN. d-Mannose, l-fucose, GlcNAc, LPS and PGN could inhibit the agglutinating activity of rPaCTLRC, while d-galactose did not functioned. PaCTLRC neutralization using anti-PaCTLRC IgG resulted in the inhibition of phagocytosis by ayu monocytes/macrophages (MO/MΦ) of S. aureus but not of E. coli, and produced a consistently higher survival rate of S. aureus than that of E. coli. d-Mannose, LPS and PGN treatment had no significant influence on the phagocytosis of ayu MO/MΦ. These results suggest that PaCTLRC may serve as a Gram-positive bacteria-preferred PRR which is involved in pathogen recognition and signal transduction in ayu MO/MΦ.
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
authors.forename: Xue-Heng
authors.initials: XH
authors.lastname: Zhang
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
authors.forename: Yu-Hong
authors.initials: YH
authors.lastname: Shi
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China; Collaborative Innovation Center for Zhejiang Marine High-efficiency and Healthy Aquaculture, Ningbo University, Ningbo 315211, China. Electronic address: jchen1975@163.com.
authors.forename: Jiong
authors.initials: J
authors.lastname: Chen
mesh_terms: D016980:Aeromonas hydrophila / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D004926:Escherichia coli / Q000276:immunology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D005786:Gene Expression Regulation; D006601:Hexoses / Q000276:immunology / Q000378:metabolism; D037181:Lectins, C-Type / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology / Q000378:metabolism; D008089:Listeria monocytogenes / Q000276:immunology; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology; D008969:Molecular Sequence Data; D009000:Monocytes / Q000276:immunology* / Q000382:microbiology; D036441:Osmeriformes / Q000145:classification / Q000235:genetics / Q000276:immunology*; D010587:Phagocytosis; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011975:Receptors, Mitogen / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D020317:Salmo salar / Q000145:classification / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013211:Staphylococcus aureus / Q000276:immunology; D014733:Vibrio / Q000276:immunology
chemical_list: D029941:Fish Proteins; D006601:Hexoses; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; D011975:Receptors, Mitogen
keywords: Bacterial killing; C-type lectin receptor; Monocytes/macrophages; Pathogen recognition; Phagocytic activity