Hu Baoqing, Wen Chungen, Zhang Ming, Jian Shaoqing, Yang Gang
School of Life Sciences, Nanchang University, Nanchang 330031, China.
School of Life Sciences, Nanchang University, Nanchang 330031, China.
Fish Shellfish Immunol. 2017 Jan;60:436-446. doi: 10.1016/j.fsi.2016.12.013. Epub 2016 Dec 12.
Lipopolysaccharide-binding protein and bactericidal permeability-increasing protein (LBP/BPI) play crucial role in modulating cellular signals in response to Gram-negative bacteria infection. In the present study, two isoforms of LBP/BPI genes, designated as HcLBP/BPI1 and HcLBP/BPI2, respectively, were cloned from the mussel Hyriopsis cumingii by RACE approach. The full-length cDNA sequences of HcLBP/BPI1 and HcLBP/BPI2 were 1887 and 2227 bp and encoded two secreted proteins of 501 and 518 amino acid residues, respectively. The deduced amino acid of HcLBP/BPI1 and HcLBP/BPI2 contained several conserved domains, such as signal peptide, two BPI/LBP and one central domain. Phylogentic analysis further supported that HcLBP/BPI1 and HcLBP/BPI2 belonged to new members of invertebrate LBP/BPI family. The mRNA transcripts of HcLBP/BPI1 and HcLBP/BPI2 were ubiquitously expressed in all examined tissues, and the expression level of HcLBP/BPI1 was higher than that of HcLBP/BPI2. The mRNA expression of HcLBP/BPI1 in hepatopancreas and hemocytes was significantly up-regulate after Aeromonas hydrophila and LPS challenge, and HcLBP/BPI2 in hepatopancreas was only up-regulated at 6 and 12 h after LPS challenge and at 12 h after A. hydrophila challenge. In addition, the recombinant HcLBP/BPIs displayed antibacterial activity against Gram-negative bacteria, and the antibacterial index of HcLBP/BPI1 was higher than that of HcLBP/BPI2. These results indicated that HcLBP/BPI1 and HcLBP/BPI2 probably played distinct roles in bacterial mediating immune response in Mollusca.
脂多糖结合蛋白和杀菌通透性增加蛋白（LBP/BPI）在调节细胞信号以应对革兰氏阴性菌感染方面发挥着关键作用。在本研究中，通过RACE方法从三角帆蚌中克隆了LBP/BPI基因的两种亚型，分别命名为HcLBP/BPI1和HcLBP/BPI2。HcLBP/BPI1和HcLBP/BPI2的全长cDNA序列分别为1887和2227 bp，分别编码两个含有501和518个氨基酸残基的分泌蛋白。HcLBP/BPI1和HcLBP/BPI2推导的氨基酸包含几个保守结构域，如信号肽、两个BPI/LBP和一个中央结构域。系统发育分析进一步支持HcLBP/BPI1和HcLBP/BPI2属于无脊椎动物LBP/BPI家族的新成员。HcLBP/BPI1和HcLBP/BPI2的mRNA转录本在所有检测组织中均有广泛表达，且HcLBP/BPI1的表达水平高于HcLBP/BPI2。嗜水气单胞菌和LPS刺激后，肝胰腺和血细胞中HcLBP/BPI1的mRNA表达显著上调，而肝胰腺中HcLBP/BPI2仅在LPS刺激后6小时和12小时以及嗜水气单胞菌刺激后12小时上调。此外，重组HcLBP/BPIs对革兰氏阴性菌具有抗菌活性，且HcLBP/BPI1的抗菌指数高于HcLBP/BPI2。这些结果表明，HcLBP/BPI1和HcLBP/BPI2可能在软体动物的细菌介导免疫反应中发挥不同作用。
