Key Laboratory of Marine Genetics and Breeding, Ministry of Education, Ocean University of China, Qingdao, 266003, China; College of Marine Science and Engineering, Nanjing Normal University, Nanjing, 210023, China.
Key Laboratory of Marine Genetics and Breeding, Ministry of Education, Ocean University of China, Qingdao, 266003, China.
Dev Comp Immunol. 2020 Oct;111:103758. doi: 10.1016/j.dci.2020.103758. Epub 2020 Jun 2.
Fish-egg lectins (FELs) have been identified in several teleost species and have been proved to play important roles in innate immune system against pathogen infection. In this study a novel fish-egg lectin (OppFEL) was identified from spotted knifejaw (Oplegnathus punctatus), and the expression patterns against bacterial infection was characterized. The amino acid sequence is highly homologous to other teleost FELs, containing five repeats of the conserved TECPR domain. Expression of OppFEL was widely observed in examined tissues, with the most abundant transcripts observed in gill, showing a pattern of tissue specific expression. The OppFEL expression was significantly up-regulated following a Gram-negative bacterium (Vibrio anguillarum) challenge in vivo, suggesting participation in host antibacterial immune responses. Recombinant OppFEL protein (rOppFEL) possessed calcium dependent binding capacities and agglutination to four Gram-negative bacterium and two Gram-positive bacterium. Sugar binding assay revealed that rOppFEL specifically bound to insoluble lipopolysaccharide and peptidoglycan. In addition, rOppFEL was also proved to have hemagglutinating activity against erythrocytes from Mus musculus, O. punctatus, Sebastes schlegelii and Paralichthys olivaceus. Dual-luciferase analysis showed that overexpression of OppFEL could suppress the activity of NF-κB in a dose dependent manner. Taken together, these results suggest that OppFEL is a unique fish-egg lectin that possesses apparent immunomodulating property and is involved in host defense against pathogens invasion.
鱼卵凝集素（FELs）已在多种硬骨鱼类中被鉴定出来，并已被证明在先天免疫系统中对抗病原体感染方面发挥着重要作用。本研究从斑点叉尾鮰（Oplegnathus punctatus）中鉴定出一种新型鱼卵凝集素（OppFEL），并对其针对细菌感染的表达模式进行了特征描述。该氨基酸序列与其他硬骨鱼类 FELs 高度同源，包含 5 个保守的 TECPR 结构域重复。OppFEL 的表达在检测到的组织中广泛存在，在鳃中观察到最丰富的转录本，表现出组织特异性表达模式。OppFEL 的表达在体内受到革兰氏阴性菌（鳗弧菌）挑战后显著上调，表明其参与宿主的抗菌免疫反应。重组 OppFEL 蛋白（rOppFEL）具有钙依赖性结合能力，并能凝集四种革兰氏阴性菌和两种革兰氏阳性菌。糖结合实验表明，rOppFEL 特异性结合不溶性脂多糖和肽聚糖。此外，rOppFEL 还被证明对来自 Mus musculus、O. punctatus、Sebastes schlegelii 和 Paralichthys olivaceus 的红细胞具有血凝活性。双荧光素酶分析表明，OppFEL 的过表达可以剂量依赖性地抑制 NF-κB 的活性。综上所述，这些结果表明 OppFEL 是一种独特的鱼卵凝集素，具有明显的免疫调节特性，并参与宿主对病原体入侵的防御。
