摘要
Hepcidin是一类富含半胱氨酸的抗菌肽,在鱼类非特异性免疫中起重要作用,具有调节铁代谢的功能。该研究克隆了香鱼hepcidin基因cDNA序列,全长763个核苷酸,包含一个完整的开放阅读框,推测编码一个由85个氨基酸组成的相对分子质量为9.7k的多肽,N端24个氨基酸是信号肽序列。香鱼hepcidin的成熟肽序列由25个氨基酸组成,含有8个半胱氨酸,可形成4个分子内二硫键结构。系统进化树分析表明,hepcidin的物种进化关系与目前接受的物种分类关系基本一致,香鱼hepcidin位于鱼类hepcidin簇中,与大西洋鲑hepcidin的亲缘关系最近,达60%。香鱼hepcidin在肝脏中表达量最大,在脾、肾、心脏和肌肉中也有表达。实时荧光定量PCR(qRT-PCR)结果表明,鳗利斯顿氏菌(Listonella anguillarum)感染以后香鱼肝组织中hepcidin基因mRNA表达量显著增加,在12h增加了8.26倍。hepcidin基因可能在香鱼抗外界病原物感染过程中起重要作用。
Hepcidin, a member of cysteine-rich antimicrobial peptides, plays an important role in both fish adaptive immunity and the regulation of iron metabolism. In this paper, the nucleotide sequence of a full-length cDNA clone for ayu （Plecoglossus altivelis） hepcidin gene, 763 nucleotides in length, was determined. Ayu hepcidin gene contained a complete open reading frame （ORF） encoding an 85-amino-acid peptide with a molecular weight of 9.7 k. A signal peptide of 24 residues existed in hepcidin N-terminus. The ayu hepcidin mature peptide sequence contained 25 amino acids with eight cysteines that formed four disulfide bonds. Sequence comparison and phylogenetic analysis showed that ayu hepcidin was most similar to Atlantic salmon （Salmo salar）, and the relationships of the different hepcidin coincided well with the evolutionary relationships of their organisms. In healthy ayu, hepcidin mRNA was mainly expressed in the liver, spleen, kidney, heart, and muscle. After Listonella anguillarum infection, liver hepcidin mRNA expression change was determined by quantitative real-time PCR （qRT-PCR） method. Hepcidin transcripts of ayu liver were significantly up-regulated and peaked at 12 h. These results suggest that hepcidin may be involved in the immune response of ayu.
基金
长江学者和创新团队发展计划项目(IRT0734)
宁波市科技创新公共服务平台项目(2007A31004)
