title: An ancient C-type lectin in Chlamys farreri (CfLec-2) that mediate pathogen recognition and cellular adhesion.
abstract: C-type lectins are a superfamily of Ca(2+) dependent carbohydrate-recognition proteins which play significant diverse roles in nonself-recognition and clearance of invaders. In the present study, a C-type lectin (CfLec-2) from Zhikong scallop Chlamys farreri was selected to investigate its functions in innate immunity. The mRNA expression of CfLec-2 in hemocytes was significantly up-regulated (P<0.01) after scallops were stimulated by LPS, PGN or β-glucan, and reached the highest expression level at 12h post-stimulation, which was 72.5-, 23.6- or 43.8-fold compared with blank group, respectively. The recombinant CfLec-2 (designated as rCfLec-2) could bind LPS, PGN, mannan and zymosan in vitro, but it could not bind β-glucan. Immunofluorescence assay with polyclonal antibody specific for CfLec-2 revealed that CfLec-2 was mainly located in the mantle, kidney and gonad. Furthermore, rCfLec-2 could bind to the surface of scallop hemocytes, and then initiated cellular adhesion and recruited hemocytes to enhance their encapsulation in vitro, and this process could be specifically blocked by anti-rCfLec-2 serum. These results collectively suggested that CfLec-2 from the primitive deuterostome C. farreri could perform two distinct immune functions, pathogen recognition and cellular adhesion synchronously, while these functions were performed by collectins and selectins in vertebrates, respectively. The synchronous functions of pathogen recognition and cellular adhesion performed by CfLec-2 tempted us to suspect that CfLec-2 was an ancient form of C-type lectin, and apparently the differentiation of these two functions mediated by C-type lectins occurred after mollusk in phylogeny.
authors.affiliation: The Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Qingdao 266071, China.
authors.forename: Jialong
authors.initials: J
authors.lastname: Yang
authors.forename: Limei
authors.initials: L
authors.lastname: Qiu
authors.forename: Xiumei
authors.initials: X
authors.lastname: Wei
authors.forename: Leilei
authors.initials: L
authors.lastname: Wang
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhou
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion; D037222:Collectins / Q000737:chemistry / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006434:Hemocytes / Q000276:immunology; D007113:Immunity, Innate; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology; D008351:Mannans / Q000276:immunology; D008958:Models, Molecular; D049897:Pectinidae / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins; D019087:Selectins / Q000737:chemistry / Q000276:immunology; D016415:Sequence Alignment; D012758:Shellfish; D015854:Up-Regulation; D015054:Zymosan / Q000276:immunology
chemical_list: D037222:Collectins; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; D008351:Mannans; D011994:Recombinant Proteins; D019087:Selectins; D015054:Zymosan