Tran Ngoc Tuan, Liu Han, Jakovlić Ivan, Wang Wei-Min
College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China.
Int J Mol Sci. 2015 Mar 30;16(4):7077-97. doi: 10.3390/ijms16047077.
MyD88 and TRAF6 play an essential role in the innate immune response in most animals. This study reports the full-length MaMyD88 and MaTRAF6 genes identified from the blunt snout bream (Megalobrama amblycephala) transcriptome profile. MaMyD88 is 2501 base pairs (bp) long, encoding a putative protein of 284 amino acids (aa), including the N-terminal DEATH domain of 78 aa and the C-terminal TIR domain of 138 aa. MaTRAF6 is 5474 bp long, encoding a putative protein of 542 aa, including the N-terminal low-complexity region, RING domain (40 aa), a coiled-coil region (64 aa) and C-terminal MATH domain (147 aa). Coding regions of MaMyD88 and MaTRAF6 genomic sequences consisted of five and six exons, respectively. Physicochemical and functional characteristics of the proteins were analysed. Alpha helices were dominant in the secondary structure of the proteins. Homology models of the MaMyD88 and MaTRAF6 domains were constructed applying the comparative modelling method. RT-qPCR was used to analyse the expression of MaMyD88 and MaTRAF6 mRNA transcripts in response to Aeromonas hydrophila challenge. Both genes were highly upregulated in the liver, spleen and kidney during the first 24 h after the challenge. While MyD88 and TRAF6 have been reported in various aquatic species, this is the first report and characterisation of these genes in blunt snout bream. This research also provides evidence of the important roles of these two genes in the blunt snout bream innate immune system.
MyD88和TRAF6在大多数动物的先天免疫反应中发挥着重要作用。本研究报告了从团头鲂（Megalobrama amblycephala）转录组图谱中鉴定出的全长MaMyD88和MaTRAF6基因。MaMyD88长2501个碱基对（bp），编码一个推定的284个氨基酸（aa）的蛋白质，包括一个78个氨基酸的N端死亡结构域和一个138个氨基酸的C端TIR结构域。MaTRAF6长5474 bp，编码一个推定的542个氨基酸的蛋白质，包括N端低复杂性区域、RING结构域（40个氨基酸）、一个卷曲螺旋区域（64个氨基酸）和C端MATH结构域（147个氨基酸）。MaMyD88和MaTRAF6基因组序列的编码区分别由5个和6个外显子组成。分析了蛋白质的理化和功能特性。α螺旋在蛋白质的二级结构中占主导地位。应用比较建模方法构建了MaMyD88和MaTRAF6结构域的同源模型。采用RT-qPCR分析MaMyD88和MaTRAF6 mRNA转录本在嗜水气单胞菌攻击后的表达情况。在攻击后的前24小时内，这两个基因在肝脏、脾脏和肾脏中均高度上调。虽然在各种水生物种中都报道过MyD88和TRAF6，但这是首次在团头鲂中报道和鉴定这些基因。本研究还提供了这两个基因在团头鲂先天免疫系统中重要作用的证据。
