College of Animal Science, Guizhou University, Guiyang, Guizhou, 550025, China; Key Laboratory of Sichuan Province for Fishes Conservation and Utilization in the Upper Reaches of the Yangtze River, Neijiang Normal University, Neijiang, 641100, China; College of Life Science, Neijiang Normal University, Neijiang, 641100, China.
Key Laboratory of Sichuan Province for Fishes Conservation and Utilization in the Upper Reaches of the Yangtze River, Neijiang Normal University, Neijiang, 641100, China; College of Life Science, Neijiang Normal University, Neijiang, 641100, China.
Fish Shellfish Immunol. 2023 Mar;134:108579. doi: 10.1016/j.fsi.2023.108579. Epub 2023 Feb 3.
Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs) that can recognize pathogen-associated molecular patterns (PMPs) and play important roles in the innate immune system in vertebrates. In this study, we identified a teleost-specific tlr22 gene from yellow catfish (Pelteobagrus fulvidraco) and its immune roles in response to different pathogens were also determined. The open reading frame (ORF) of the tlr22 was 2892 bp in length, encoding a protein of 963 amino acids. Multiple protein sequences alignment, secondary and three-dimensional structure analyses revealed that TLR22 is highly conserved among different fish species. Phylogenetic analysis showed that the phylogenetic topology was divided into six families of TLR1, TLR3, TLR4, TLR5, TLR7 and TLR11, and TLR22 subfamily was clustered into TLR11 family. Meanwhile, synteny and gene structure comparisons revealed functional and evolutionary conservation of the tlr22 gene in teleosts. Furthermore, tlr22 gene was shown to be widely expressed in detected tissues except barbel and eye, with highest expression level in liver. The transcription of tlr22 was significantly increased in spleen, kidney, liver and gill tissues at different timepoints after Poly I:C infection, suggesting TLR22 plays critical roles in defensing virus invasion. Similarly, the transcription of tlr22 was also dramatically up-regulated in spleen, kidney and gill tissues with different patterns after Aeromonas hydrophila infection, indicating that TLR22 is also involved in resisting bacteria invasion. Our findings will provide a solid basis for the investigation the immune functions of tlr22 gene in teleosts, as well as provide useful information for disease control and treatment for yellow catfish.
Toll 样受体（TLRs）是一类能够识别病原体相关分子模式（PAMPs）的模式识别受体（PRRs），在脊椎动物的固有免疫系统中发挥重要作用。本研究从黄颡鱼（Pelteobagrus fulvidraco）中鉴定了一个硬骨鱼类特异性的 tlr22 基因，并确定了其对不同病原体的免疫作用。tlr22 的开放阅读框（ORF）长 2892bp，编码 963 个氨基酸的蛋白质。多种蛋白序列比对、二级和三维结构分析表明，TLR22 在不同鱼类中高度保守。系统发育分析表明，系统发育拓扑结构分为 TLR1、TLR3、TLR4、TLR5、TLR7 和 TLR11 六个家族，TLR22 亚家族聚类到 TLR11 家族。同时，基因结构比较表明 TLR22 基因在硬骨鱼类中具有功能和进化保守性。此外，tlr22 基因在检测到的组织中广泛表达，除了须和眼，在肝脏中表达水平最高。在 Poly I:C 感染后不同时间点，脾、肾、肝和鳃组织中 tlr22 基因的转录显著增加，表明 TLR22 在抵抗病毒入侵中发挥关键作用。同样，在感染嗜水气单胞菌后，脾、肾和鳃组织中 tlr22 的转录也显著上调，表明 TLR22 也参与抵抗细菌入侵。我们的研究结果为研究 TLR22 基因在硬骨鱼类中的免疫功能提供了坚实的基础，并为黄颡鱼的疾病防控和治疗提供了有用的信息。
