Bi Wen-Jie, Li Dian-Xiang, Xu Yi-Hui, Xu Sen, Li Jing, Zhao Xiao-Fan, Wang Jin-Xing
Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, China.
Biotechnology Department, School of Biological Sciences and Biotechnology, University of Jinan, Jinan 250022, China.
Dev Comp Immunol. 2015 Jul;51(1):10-21. doi: 10.1016/j.dci.2015.02.001. Epub 2015 Feb 16.
Scavenger receptors (SRs) are involved in innate immunity through recognizing pathogen-associated molecular patterns (PAMPs) and in pathogenesis of diseases through interactions with damage-associated molecular patterns (DAMPs). The roles of SRs in invertebrate innate immunity still need to be elucidated. Here we identify a class B scavenger receptor from kuruma shrimp, Marsupenaeus japonicus, designated MjSR-B1. The recombinant MjSR-B1 agglutinated bacteria in a calcium dependent manner and bound lipopolysaccharide and lipoteichoic acid. After knockdown of MjSR-B1, both the bacterial clearance and phagocytotic ability of M. japonicus against V. anguillarum and S. aureus were impaired, and several phagocytosis related genes were downregulated. The expression levels of antimicrobial peptides were also downregulated. Overexpression of MjSR-B1 led to enhanced bacterial clearance, phagocytosis rate and upregulation of phagocytosis-related and antimicrobial peptide genes. However, overexpression of mutant MjSR-B1ΔC, which lacks the carboxyl tail of MjSR-B1, had none of these effects. Our results indicate that MjSR-B1 can protect shrimp from bacteria by promoting phagocytosis and by enhancing the expression of antimicrobial peptides.
清道夫受体（SRs）通过识别病原体相关分子模式（PAMPs）参与固有免疫，并通过与损伤相关分子模式（DAMPs）相互作用参与疾病的发病机制。SRs在无脊椎动物固有免疫中的作用仍有待阐明。在此，我们从日本对虾（Marsupenaeus japonicus）中鉴定出一种B类清道夫受体，命名为MjSR-B1。重组MjSR-B1以钙依赖方式凝集细菌，并结合脂多糖和脂磷壁酸。敲低MjSR-B1后，日本对虾对鳗弧菌（V. anguillarum）和金黄色葡萄球菌（S. aureus）的细菌清除能力和吞噬能力均受损，且几个与吞噬作用相关的基因表达下调。抗菌肽的表达水平也下调。MjSR-B1的过表达导致细菌清除能力增强、吞噬率提高以及吞噬作用相关基因和抗菌肽基因上调。然而，缺乏MjSR-B1羧基末端的突变体MjSR-B1ΔC的过表达没有这些作用。我们的结果表明，MjSR-B1可通过促进吞噬作用和增强抗菌肽表达来保护对虾免受细菌侵害。
