Huang Lili, Fan Yuding, Zhou Yong, Jiang Nan, Liu Wenzhi, Meng Yan, Zeng Lingbing
College of Fisheries and Biosciences, Shanghai Ocean University, Shanghai 201306, China.
Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, Hubei 430223, China.
Comp Biochem Physiol B Biochem Mol Biol. 2015 Jun;184:52-7. doi: 10.1016/j.cbpb.2015.02.006. Epub 2015 Mar 6.
The Chinese giant salamander, Andrias davidianus, is the largest extant amphibian species in the world, which is of significance due to its specific position in the evolutionary history of vertebrates. Currently, limited information about the innate immune system of this animal is known. In this study, the toll-like receptor 7 (TLR7), designated CgsTLR7, was cloned from Chinese giant salamander, A. davidianus. The full-length cDNA of CgsTLR7 is 3747 bp, with an open reading frame of 3150 bp, encoding 1049 amino acids. The TLR family motifs, including the leucine-rich repeat (LRR) and Toll/interleukin (IL)-1 receptor (TIR) domain are conserved in CgsTLR7, which includes 19 LRRs and a TIR domain. The predicted amino acid sequence of CgsTLR7 has 71%, 65%, 63% and 55% identity with turtle, chicken, human and fugu TLR7 homologues, respectively. Phylogenetic analysis showed that CgsTLR7 is closest to that of frog TLR7 among the examined species. Quantitative real-time PCR analysis revealed broad expression of CgsTLR7 in tissues from apparently healthy Chinese giant salamanders with the highest expression in the liver and the lowest expression in the intestine. The mRNA expression was up-regulated and reached a peak level in the kidney, liver and spleen at 12 h, 24 h and 48 h after infecting the animals with the giant salamander iridovirus (GSIV), respectively. These results suggest that CgsTLR7 has a conserved gene structure and might play an important role in immune regulation against viral infections in the Chinese giant salamander.
中国大鲵（Andrias davidianus）是世界上现存最大的两栖动物物种，由于其在脊椎动物进化史上的特殊地位而具有重要意义。目前，关于这种动物先天免疫系统的信息有限。在本研究中，从中国大鲵（A. davidianus）中克隆了Toll样受体7（TLR7），命名为CgsTLR7。CgsTLR7的全长cDNA为3747 bp，开放阅读框为3150 bp，编码1049个氨基酸。TLR家族基序，包括富含亮氨酸重复序列（LRR）和Toll/白细胞介素（IL）-1受体（TIR）结构域，在CgsTLR7中是保守的，其中包括19个LRR和一个TIR结构域。CgsTLR7的预测氨基酸序列与龟、鸡、人及河豚TLR7同源物的同一性分别为71%、65%、63%和55%。系统发育分析表明，在所检测的物种中，CgsTLR7与青蛙TLR7的亲缘关系最近。定量实时PCR分析显示，CgsTLR7在外观健康的中国大鲵组织中广泛表达，在肝脏中表达最高，在肠道中表达最低。在用大鲵虹彩病毒（GSIV）感染动物后，肾脏、肝脏和脾脏中的mRNA表达分别在12小时、24小时和48小时上调并达到峰值水平。这些结果表明，CgsTLR7具有保守的基因结构，可能在中国大鲵抗病毒感染的免疫调节中发挥重要作用。
