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.
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; Shandong Vocational Animal Science and Veterinary College, Weifang 261021, Shandong Province, China.
Int J Biol Macromol. 2022 Oct 1;218:878-890. doi: 10.1016/j.ijbiomac.2022.07.201. Epub 2022 Jul 29.
TLR3 plays a crucial role in innate immunity. In the present study, OnTLR3 was identified in the Nile tilapia Oreochromis niloticus, with a conserved LRR domain and a C-terminal TIR domain. OnTLR3 was broadly expressed in all tissues tested, with the highest expression levels in the blood and the lowest in the kidney. TLR3 mRNA could be detected from pharyngula (2.5 dpf) to late larva (8.5 dpf) during embryonic and larval development. Moreover, the expression level of OnTLR3 was clearly altered in all five tissues after Streptococcus agalactiae infection in vivo and could be induced by LPS, poly(I:C), S. agalactiae WC1535 and △CPS in Nile tilapia macrophages. When OnTLR3 was overexpressed in 293 T cells, it was distributed in the cytoplasm and could significantly increase NF-κB activation. The pulldown assays showed that OnTLR3 interacted with both OnMyD88 and OnTRIF. The binding assays revealed the specificity of OnTLR3 for pathogen-associated molecular patterns (PAMPs) and bacteria that included S. agalactiae, Aeromonas hydrophila and poly(I:C), LPS and PGN. Taken together, these findings suggest that OnTLR3, as a pattern recognition receptor (PRR), might play an important role in the immune response to pathogen invasion.
TLR3 在先天免疫中发挥着至关重要的作用。在本研究中，我们在尼罗罗非鱼 Oreochromis niloticus 中鉴定出了 OnTLR3，它具有保守的 LRR 结构域和 C 端 TIR 结构域。OnTLR3 在所有测试的组织中均广泛表达，在血液中的表达水平最高，在肾脏中的表达水平最低。在胚胎和幼体发育过程中，从咽胚期（2.5 dpf）到晚期幼体（8.5 dpf）都可以检测到 TLR3 mRNA。此外，在体内感染无乳链球菌和用 LPS、poly(I:C)、无乳链球菌 WC1535 和 △CPS 刺激后，OnTLR3 在所有 5 种组织中的表达水平均明显改变。当 OnTLR3 在 293T 细胞中过表达时，它分布在细胞质中，可以显著增加 NF-κB 的激活。下拉实验表明 OnTLR3 与 OnMyD88 和 OnTRIF 相互作用。结合实验揭示了 OnTLR3 对病原体相关分子模式（PAMPs）和细菌的特异性，包括无乳链球菌、嗜水气单胞菌和 poly(I:C)、LPS 和 PGN。综上所述，这些发现表明 OnTLR3 作为一种模式识别受体（PRR），可能在对病原体入侵的免疫反应中发挥重要作用。
