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核转录因子κB抑制因子α(IκBα)是NFκB/IκB信号传导通路的重要成员,参与机体抗细菌感染等多种免疫反应,可通过蛋白质间的相互作用结合核转录因子NFκB,从而调控生物体多种免疫基因表达。该研究采用RACE技术从香鱼中克隆得到核转录因子κB抑制因子PaIκBα基因的cDNA全长序列(1341bp,GenBank Accession No.JN801027),开放阅读框ORF为936bp,编码311个氨基酸,5’非编码区为64bp,3’非编码区为341bp。生物信息学分析表明,香鱼IκBα蛋白的序列中包含5个保守的锚蛋白重复序列,N末端含有信号诱导蛋白,C末端含有PEST序列。同源性比对结果表明,香鱼IκBα蛋白与胡瓜鱼IκBα的同源性最高,为95%;其次是大西洋鲑、虹鳟、尼罗罗非鱼和鳜鱼等,同源性分别为76%、75%、70%和68%。系统进化树分析表明,香鱼IκBα蛋白与胡瓜鱼、虹鳟、尼罗罗非鱼、鳜鱼和大西洋鲑等亲缘关系最近。RT-PCR分析表明,PaIκBα基因在香鱼肝脏、肾脏、脾脏和鳃中表达水平较高,其次是肠、脑和肌肉,在心脏中表达极少。嗜水气单胞菌(Aeromonas hydrophil)感染香鱼后,PaIκBα基因表达增强,感染24h达最大值,表明PaIκBα基因在香鱼受到嗜水气单胞菌刺激的免疫过程中可能发挥着重要作用。
Nuclear factor κB inhibitor (IκBα) is an important member of NFκB / IκB signal transduction pathway. It participates in a variety of immune responses such as anti-bacterial infection. It can bind to nuclear factor NFκB through the interaction of proteins, Immune gene expression. In this study, the full-length cDNA sequence of PaIκBα (1341bp, GenBank Accession No.JN801027) was cloned from sweetfish by using RACE technique. The open reading frame ORF was 936bp, encoding a protein of 311 amino acids with 5 ’non-coding The region is 64 bp and the 3 ’non-coding region is 341 bp. Bioinformatics analysis showed that the sequence of the sweetfish IκBα protein contained five conserved ankyrin repeats, the N-terminal signal-induced protein and the C-terminal PEST sequence. Homology comparison showed that the homology of the IκBα protein of smelt with IκBα was the highest (95%), followed by that of Atlantic salmon, rainbow trout, Nile tilapia and anchovy, with homologies of 76% , 75%, 70% and 68%. Phylogenetic tree analysis showed that the sweetfish IκBα protein was the most closely related to smelt, rainbow trout, Nile tilapia, anchovy and Atlantic salmon. RT-PCR analysis showed that the PaIκBα gene was highly expressed in the liver, kidney, spleen and gill of the sweetfish, followed by the intestine, brain and muscle, with little expression in the heart. After infected with Aeromonas hydrophil, the expression of PaIκBα gene was enhanced, reaching the maximum at 24h, indicating that PaIκBα gene may play an important role in the immune process of A. hydrophila stimulated by Aeromonas hydrophila.