School of Life Science, East China Normal University, Dong-Chuan Road No. 500, Shanghai 200241, China.
Fish Shellfish Immunol. 2013 Nov;35(5):1554-65. doi: 10.1016/j.fsi.2013.08.021. Epub 2013 Sep 5.
As pattern recognition receptors (PRRs), C-type lectins (CTLs) play significant roles in recognizing and eliminating pathogens in innate immunity. In this study, a novel CTL (EsLecD) was identified from the crustacean Eriocheir sinensis. The cloning of full-length EsLecD cDNA was based on the initial expressed sequence tags (ESTs) isolated from a hepatopancreatic cDNA library. The full-length EsLecD cDNA of 686 bp with an open reading frame of 468 bp encodes a putative protein of 155 aa residues, including an N-terminal signal peptide and a single carbohydrate-recognition domain (CRD). By quantitative RT-PCR analysis, the EsLecD transcript was mainly detected in the hepatopancreas but rarely in other tissues, and it was significantly upregulated in the hepatopancreas after immune challenge with lipopolysaccharides. The recombinant EsLecD protein (rEsLecD) exhibited the ability to bind to all tested microorganisms, including bacteria and yeast. Meanwhile, calcium significantly increased the binding affinity of rEsLecD toward microorganisms, but it was not essential. The binding of rEsLecD induced the aggregation of microbial pathogens. Moreover, rEsLecD was capable of inhibiting the growth of microorganisms and even directly killing bacteria. Interestingly, rEsLecD could stimulate cellular encapsulation in vitro. In conclusion, results of this study suggest that EsLecD acts as an antibacterial PRR participating in the innate immunity of invertebrates.
作为模式识别受体(PRRs),C 型凝集素(CTLs)在先天免疫中识别和消除病原体方面发挥着重要作用。在这项研究中,从甲壳动物中华绒螯蟹中鉴定出一种新型 CTL(EsLecD)。全长 EsLecD cDNA 的克隆基于从肝胰腺 cDNA 文库中分离的初始表达序列标签(ESTs)。全长 EsLecD cDNA 为 686 bp,开放阅读框为 468 bp,编码 155 个氨基酸残基的假定蛋白,包括一个 N 端信号肽和一个单一的碳水化合物识别结构域(CRD)。通过定量 RT-PCR 分析,EsLecD 转录本主要在肝胰腺中检测到,但在其他组织中很少检测到,并且在免疫脂多糖刺激后肝胰腺中显著上调。重组 EsLecD 蛋白(rEsLecD)表现出与所有测试的微生物(包括细菌和酵母)结合的能力。同时,钙显著增加了 rEsLecD 对微生物的结合亲和力,但不是必需的。rEsLecD 的结合诱导了微生物病原体的聚集。此外,rEsLecD 能够抑制微生物的生长,甚至直接杀死细菌。有趣的是,rEsLecD 可以在体外刺激细胞包裹。总之,这项研究的结果表明,EsLecD 作为一种参与无脊椎动物先天免疫的抗菌 PRR 发挥作用。