Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.
College of Aquaculture and Fisheries, Can Tho University, Viet Nam.
Fish Shellfish Immunol. 2023 Aug;139:108902. doi: 10.1016/j.fsi.2023.108902. Epub 2023 Jun 16.
Nile tilapia (Oreochromis niloticus) is one of the major food fish worldwide. The farming business, on the other hand, has faced considerable obstacles, such as disease infestations. Toll-like receptors (TLRs) play an important function in the activation of the innate immune system in response to infections. Unc-93 homolog B1 (UNC93B1) is a key regulator of nucleic acid (NA)-sensing TLRs. Here the UNC93B1 gene, which was cloned from Nile tilapia tissue for this investigation, had the same genetic structure as a homologous gene in humans and mice. Phylogenetic analysis revealed that Nile tilapia UNC93B1 clustered with UNC93B1 from other species and separately from the UNC93A clade. The gene structure of the Nile tilapia UNC93B1 was found to be identical to that of human UNC93B1. Our gene expression studies revealed that Nile tilapia UNC93B1 was highly expressed in the spleen, followed by other immune-related tissues such as the head kidney, gills, and intestine. Moreover, Nile tilapia UNC93B1 mRNA transcripts were up-regulated in vivo in the head kidney and spleen tissues from poly I:C and Streptococcus agalactiae injected Nile tilapia, as well as in vitro in LPS stimulated Tilapia head kidney (THK) cells. The Nile tilapia UNC93B1-GFP protein signal was detected in the cytosol of THK cells and was co-localized with endoplasmic reticulum and lysosome but not with mitochondria. Moreover, the results of a co-immunoprecipitation and immunostaining analysis showed that Nile tilapia UNC93B1 can be pulled down with fish-specific TLRs such as TLR18 and TLR25 from Nile tilapia, and was found to be co-localized with these fish-specific TLRs in the THK cells. Overall, our findings highlight the potential role of UNC93B1 as an accessory protein in fish-specific TLR signaling.
尼罗罗非鱼（Oreochromis niloticus）是世界上主要的食用鱼类之一。然而，水产养殖业务面临着许多挑战，其中包括疾病的侵袭。Toll 样受体（TLRs）在对感染的固有免疫系统的激活中发挥着重要作用。UNC93B1 是核酸（NA）感应 TLR 信号的关键调节因子。本研究从尼罗罗非鱼组织中克隆出 UNC93B1 基因，该基因与人类和小鼠的同源基因具有相同的遗传结构。系统发育分析表明，尼罗罗非鱼 UNC93B1 与其他物种的 UNC93B1 聚类，而与 UNC93A 聚类分开。尼罗罗非鱼 UNC93B1 的基因结构与人类 UNC93B1 相同。我们的基因表达研究表明，尼罗罗非鱼 UNC93B1 在脾脏中高度表达，其次是其他免疫相关组织，如头肾、鳃和肠。此外，在注射聚肌苷酸和无乳链球菌的尼罗罗非鱼头肾和脾脏组织以及体外 LPS 刺激的罗非鱼头肾（THK）细胞中，尼罗罗非鱼 UNC93B1mRNA 转录物在体内被上调。尼罗罗非鱼 UNC93B1-GFP 蛋白信号在 THK 细胞的细胞质中被检测到，并与内质网和溶酶体共定位，但与线粒体不共定位。此外，免疫共沉淀和免疫染色分析的结果表明，尼罗罗非鱼 UNC93B1 可以与尼罗罗非鱼特异性 TLRs（如 TLR18 和 TLR25）一起从 THK 细胞中下拉，并且与这些鱼特异性 TLRs 在 THK 细胞中共定位。总之，我们的研究结果强调了 UNC93B1 作为鱼特异性 TLR 信号的辅助蛋白的潜在作用。
