Sun Jiejie, Wang Lingling, Yang Chuanyan, Song Linsheng
Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, 52 Heishijiao Street, Dalian 116023, China; Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian 116023, China.
Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, 52 Heishijiao Street, Dalian 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China; Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian 116023, China; Dalian Key Laboratory of Aquatic Animal Diseases Prevention and Control, Dalian Ocean University, Dalian 116023, China.
iScience. 2020 Feb 21;23(2):100834. doi: 10.1016/j.isci.2020.100834. Epub 2020 Jan 11.
BCR/TCR-based adaptive immune systems arise in the jawed vertebrates, and B cell receptors (BCRs) play an important role in the clonal selection of B cells and their differentiation into antibody-secreting plasma cells. The existence of BCR-like molecule and the activation mechanism of the downstream response are still not clear in invertebrates. In this study, an ancient BCR-like molecule (designated as CgIgR) with an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic tail was identified from the Pacific oyster Crassostrea gigas to investigate its involvement in immune response. CgIgR could bind different bacteria through five extracellular Ig domains and formed dimers. The activated CgIgR recruited CgSyk to promote CgERK phosphorylation. The CgIgR-mediated signaling promoted the production of immunoglobulin domain-containing proteins (CgICP-2 and CgLRRIG-1) through inducing CgH3K4me2. The produced CgICPs eventually facilitated hemocytes to phagocytize and eliminate V. splendidus. This study proposed that there was an ancient BCR-like molecule and BCR-like signaling in molluscs.
基于BCR/TCR的适应性免疫系统出现在有颌脊椎动物中，B细胞受体（BCR）在B细胞的克隆选择及其分化为分泌抗体的浆细胞过程中发挥重要作用。在无脊椎动物中，类BCR分子的存在及其下游反应的激活机制仍不清楚。在本研究中，从太平洋牡蛎（Crassostrea gigas）中鉴定出一种古老的类BCR分子（命名为CgIgR），其胞质尾部含有基于免疫受体酪氨酸的激活基序（ITAM），以研究其在免疫反应中的作用。CgIgR可通过五个细胞外Ig结构域结合不同细菌并形成二聚体。活化的CgIgR招募CgSyk以促进CgERK磷酸化。CgIgR介导的信号传导通过诱导CgH3K4me2促进含免疫球蛋白结构域蛋白（CgICP-2和CgLRRIG-1）的产生。产生的CgICPs最终促进血细胞吞噬并清除灿烂弧菌。本研究提出，在软体动物中存在一种古老的类BCR分子和类BCR信号传导。
