Key Laboratory of Tropical & Subtropical Fishery Resource Application & Cultivation, Ministry of Agriculture, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Science, Guangzhou, 510380, China; Guangdong Provincial Key Laboratory of Aquatic Animal Immune Technology, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Science, Guangzhou, 510380, China.
Shandong Vocational Animal Science and Veterinary College, Weifang, 261021, Shandong Province, China.
Dev Comp Immunol. 2022 Aug;133:104409. doi: 10.1016/j.dci.2022.104409. Epub 2022 Apr 9.
Toll-like receptor 5 (TLR5) is responsible for bacterial flagellin recognition in vertebrates. In the present study, TLR5M was identified in the Nile tilapia Oreochromis niloticus (OnTLR5), containing a conserved LRR domain, a transmembrane region and a C-terminal TIR domain, similar to that of other fishes and mammals. OnTLR5 was broadly expressed in all the tissues examined, presenting the highest expression levels in the blood and the lowest in the kidney. OnTLR5 was detected from 2 d postfertilization (dpf) to 8 dpf during embryonic development. Moreover, expression levels of OnTLR5 were clearly altered in all five tissues examined in response to Streptococcus agalactiae infection in vivo. Overexpression of OnTLR5 in HEK293T cells revealed that OnTLR5 was distributed in the cytoplasm and significantly increased NF-κB activation. In response to cotransfection with OnMyd88, OnTLR5 significantly upregulated OnMyd88-induced NF-κB activation. Pulldown assays showed that OnTLR5 interacts with OnMyd88 and revealed an interaction between TLR5 and Aeromonas hydrophila flagellin. Taken together, these findings suggest that OnTLR5 plays important roles in TLR/IL-1R signalling pathways and the immune response to pathogen invasion.
Toll 样受体 5（TLR5）负责脊椎动物对细菌鞭毛蛋白的识别。本研究在尼罗罗非鱼（Oreochromis niloticus）（OnTLR5）中鉴定出 TLR5M，其包含保守的 LRR 结构域、跨膜区域和 C 端 TIR 结构域，与其他鱼类和哺乳动物相似。OnTLR5 在所有检测的组织中广泛表达，在血液中的表达水平最高，在肾脏中的表达水平最低。在胚胎发育过程中，从受精后 2 天（dpf）到 8 天（dpf）可以检测到 OnTLR5。此外，在体内受到无乳链球菌感染时，所有五个检测的组织中 OnTLR5 的表达水平均明显改变。在 HEK293T 细胞中过表达 OnTLR5 表明，OnTLR5 分布在细胞质中，并显著增加 NF-κB 的激活。与 OnMyd88 共转染时，OnTLR5 显著上调了 OnMyd88 诱导的 NF-κB 激活。下拉测定表明 OnTLR5 与 OnMyd88 相互作用，并揭示了 TLR5 与嗜水气单胞菌鞭毛蛋白之间的相互作用。总之，这些发现表明 OnTLR5 在 TLR/IL-1R 信号通路和对病原体入侵的免疫反应中发挥重要作用。
