半滑舌鳎多聚免疫球蛋白受体(pIgR)基因的克隆和表达分析

Cloning and Expression Analysis of the Polymeric Immunoglobulin Receptor (pIgR) Gene in the Half Smooth Tongue Sole (Cynoglossus semilaevis)

中文关键词: 半滑舌鳎  多聚免疫球蛋白受体基因  病原感染  免疫应答

英文关键词: Cynoglossus semilaevis  Polymeric immunoglobulin receptor (pIgR) gene  Pathogen challenge  Immune response

中文摘要:

      本研究根据半滑舌鳎(Cynoglossus semilaevis)基因组数据库中预测的多聚免疫球蛋白受体(Polymeric immunoglobulin receptor, pIgR)序列，通过PCR和RACE技术获得了半滑舌鳎pIgR基因cDNA，全长为1419 bp，开放阅读框(ORF)为1020 bp，编码339个氨基酸，5¢UTR区域为109 bp，3¢UTR区域为290 bp。保守结构域分析显示，半滑舌鳎pIgR蛋白包含1个信号肽，2个免疫球蛋白功能域(Ig-like domain, ILD)和1个跨膜结构域。经蛋白序列同源比对和系统进化树分析，发现半滑舌鳎pIgR与大菱鲆(Scophthalmus maximus)和牙鲆(Paralichthy solivaceus)的pIgR亲缘关系最近。实时荧光定量PCR分析显示，pIgR基因在健康半滑舌鳎的不同组织中均有表达，在鳃中表达较高，在肌肉中表达最低。经哈维氏弧菌(Vibrio harveyi)病原感染刺激后，pIgR基因在半滑舌鳎的5个组织(肝脏、脾脏、肾脏、肠和鳃)中均呈先上升后下降的趋势，其中，在脾脏和鳃中48 h达到最高值，在肝脏、肾脏和肠中72 h达到峰值。与内脏组织不同的是，pIgR基因在皮肤中呈一直上升的趋势。上述结果表明，pIgR基因在半滑舌鳎抵御哈维氏弧菌的免疫应答中发挥重要作用。

英文摘要:

      In this study, the full-length cDNA sequence of the polymeric immunoglobulin receptor (pIgR) gene of the half-smooth tongue sole (Cynoglossus semilaevis) was obtained on the basis of its predicted sequence. The cDNA sequence was 1419 bp and included an open reading frame (1020 bp, encoding 339 amino acids), a 5¢-UTR region (109 bp), and a 3¢-UTR region (290 bp). Conserved domain analysis revealed that the pIgR protein of the half-smooth tongue sole contained one signal peptide, two immunoglobulin-like domains, and one transmembrane domain. According to the protein sequence homology alignment and phylogenetic tree analysis, the pIgR sequence of the half-smooth tongue sole had high similarity with the turbot (Scophthalmus maximus) and Japanese flounder (Paralichthys olivaceus) pIgR sequences. Real-time PCR analysis of pIgR expression in different tissues of healthy half-smooth tongue sole showed that the highest expression was in the gill and the lowest expression in muscles. After pathogen challenge with Vibrio harveyi, pIgR expression initially increased and then decreased in five tissues (liver, spleen, kidney, intestine, and gill) of the half-smooth tongue sole, with the peak time point being at 48 h in the spleen and gill, and 72 h in the liver, kidney, and intestine. Unlike in the internal organs, pIgR expression in the skin was continually upregulated. These results indicate that pIgR is involved in the immune response of the half-smooth tongue sole toward bacterial pathogens, and this finding may contribute to the discovery of an antibacterial gene marker.