A novel phagocytic receptor (CgNimC) from Pacific oyster Crassostrea gigas with lipopolysaccharide and gram-negative bacteria binding activity. Issue 1 (March 2015)

• Record Type: Journal Article
• Authors: Wang, Weilin; Liu, Rui; Zhang, Tao; Zhang, Ran; Song, Xuan; Wang, Lingling; Song, Linsheng
• Is Part Of: Fish & shellfish immunology. Volume 43:Issue 1(2015:Mar.)
• Page Start: 103
• Page End: 110
• Publication Date: 2015-03
• Subjects: Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2014.12.019
• Languages: English
• ISSNs: 1050-4648

Abstract

<abstract xml:lang="en" abstract-type="author" id="abs0010"> <title id="sectitle0010">Abstract</title> <sec> <p id="abspara0010">Phagocytosis is an evolutionarily conserved process to ingest the invading microbes and apoptotic or necrotic corpses, playing vital roles in defensing invaders and maintenance of normal physiological conditions. In the present study, a new Nimrod family phagocytic receptor with three EGF-like domains was identified in Pacific oyster <italic>Crassostrea gigas</italic> (designated <italic>Cg</italic>NimC). <italic>Cg</italic>NimC shared homology with other identified multiple EGF-like domain containing proteins. The mRNA transcripts of <italic>Cg</italic>NimC were mainly distributed in mantle and hemocytes. Its relative expression level in hemocytes was significantly (<italic>P</italic> < 0.01) up-regulated after the injection of bacteria <italic>Vibrio anguillarum</italic>. Different to the NimC in <italic>Drosophila</italic> and <italic>Anopheles gambiae</italic>, the recombinant protein of <italic>Cg</italic>NimC (r<italic>Cg</italic>NimC) could bind directly to two gram-negative bacteria <italic>V</italic>. <italic>anguillarum</italic> and <italic>Vibrio splendidus</italic>, but not to gram-positive bacteria <italic>Staphylococci aureus</italic>, <italic>Micrococcus luteus</italic> or fungi <italic>Yarrowia lipolytica</italic> and <italic>Pichia pastoris</italic>. The affinity of r<italic>Cg</italic>NimC toward <italic>M</italic>. <italic>luteus</italic> and <italic>Y</italic>. <italic>lipolytica</italic> was enhanced when the microorganisms were pre-incubated with the cell free hemolymph. r<italic>Cg</italic>NimC exhibited higher affinity to lipopolysaccharide (LPS) and relatively lower affinity to peptidoglycan (PGN), while no affinity to glucan (GLU). After the <italic>Cg</italic>NimC receptor was blocked by anti-r<italic>Cg</italic>NimC antibody <italic>in vitro</italic>, the phagocytic rate of hemocytes toward two gram-negative bacteria <italic>V</italic>. <italic>anguillarum</italic> and <italic>V</italic>. <italic>splendidus</italic> was reduced significantly (<italic>P</italic> < 0.05), but no significant change of phagocytic rate was observed toward <italic>M</italic>. <italic>luteus</italic> and <italic>Y</italic>. <italic>lipolytica</italic>. All these results implied that <italic>Cg</italic>NimC, with significant binding capability to LPS and gram-negative bacteria, was a novel phagocytic receptor involved in immune response of Pacific oyster. Further, it was speculated that receptors of Nimrod family might function as a phagocytic receptor to recognize PAMPs on the invaders and its recognition could be promoted by opsonization of molecules in hemolymph.</p> </sec> </abstract>