A soluble FcγR homolog inhibits Ig M antibody production in ayu spleen cells  

作　　者：Kai Chen Yu-Hong Shi Jiong Chen Ming-Yun Li 

机构地区：[1]Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo Zhejiang 315832, China [2]State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo Zhejiang 315211, China

出　　处：《Zoological Research》2019年第5期404-415,共12页动物学研究（英文）

基　　金：supported by the Program for the National Natural Science Foundation of China(31772876;31402323;31372555);Natural Science Foundation of Zhejiang Province(LZ18C190001;LY14C190007);Scientific Innovation Team Project of Ningbo(2015C110018);Natural Science Foundation of Ningbo City of China(2018A610225);Ningbo Science and Technology “Fumin Engineering”Project(2017C10037);K.C.Wong Magna Fund in Ningbo University

摘　　要：Classical Fc receptors (FcRs) mediate the binding to and recognition of the Fc portion of antibodies and play an important role during immune responses in mammals. Although proteins similar to soluble FcRs have been identified in fish, little is known about the role of such proteins in fish immunity. Here, we cloned a cDNA sequence encoding a soluble Fc receptor for an immunoglobulin G (FcγR) homolog from ayu (Plecoglossus altivelis)(PaFcγRl). The predicted protein was composed of two immunoglobulin C2-like domains but lacked a transmembrane segment and a cytoplasmic tail. The PaFcγRl transcripts were distributed at low levels in all tested tissues, but significantly increased after Vibrio anguillarum infection. The PaFcγRl protein was expressed in the head kidney, trunk kidney, and neutrophils. Recombinant PaFcγRl (rPaFcγRl) was secreted when transfected into mammalian cells and the native protein was also detected in serum upon infection. rPaFcγRl was also demonstrated to bind to ayu IgM, as assessed by cell transfection. Suppressive activity of the recombinant mature protein of PaFcγRl (rPaFcγRlm) on in vitro anti-sheep red blood cell (SRBC) responses was detected by a modified hemolytic plaque forming cell assay. In conclusion, our study revealed that PaFcγRl is closely involved in the negative regulation of IgM production in the ayu spleen.Classical Fc receptors(FcRs) mediate the binding to and recognition of the Fc portion of antibodies and play an important role during immune responses in mammals. Although proteins similar to soluble FcRs have been identified in fish, little is known about the role of such proteins in fish immunity. Here, we cloned a cDNA sequence encoding a soluble Fc receptor for an immunoglobulin G(FcγR) homolog from ayu(Plecoglossus altivelis)(PaFcγRl). The predicted protein was composed of two immunoglobulin C2-like domains but lacked a transmembrane segment and a cytoplasmic tail. The PaFcγRl transcripts were distributed at low levels in all tested tissues, but significantly increased after Vibrio anguillarum infection. The Pa FcγRl protein was expressed in the head kidney, trunk kidney, and neutrophils. Recombinant Pa FcγRl(rPaFcγRl) was secreted when transfected into mammalian cells and the native protein was also detected in serum upon infection. rPaFcγRl was also demonstrated to bind to ayu IgM, as assessed by cell transfection.Suppressive activity of the recombinant mature protein of PaFcγRl(rPa FcγRlm) on in vitro antisheep red blood cell(SRBC) responses was detected by a modified hemolytic plaque forming cell assay. In conclusion, our study revealed that Pa FcγRl is closely involved in the negative regulation of IgM production in the ayu spleen.

关 键 词：SOLUBLE FCΓR HOMOLOG Sequence characterization IgM-binding protein Inhibition of IGM production Plecoglossus altivelis 

分 类 号：Q953[生物学—动物学]