Pearl River Fisheries Research Institute/Key Laboratory of Tropical & Subtropical Fishery Resource Application & Cultivation, Ministry of Agriculture, Chinese Academy of Fishery Science, Guangzhou, 510380, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China.
Pearl River Fisheries Research Institute/Key Laboratory of Tropical & Subtropical Fishery Resource Application & Cultivation, Ministry of Agriculture, Chinese Academy of Fishery Science, Guangzhou, 510380, China; Guangdong Provincial Key Laboratory of Aquatic Animal Immune Technology, Guangzhou, 510380, China.
Mol Immunol. 2022 Mar;143:7-16. doi: 10.1016/j.molimm.2021.12.020. Epub 2022 Jan 3.
DDX43 is one of the members of the DExD/H-box protein family, and emerging data suggest that it may play an important role in antiviral immunity across mammals. However, little is known about DDX43 in the fish immune response. In this study, we isolated the cDNA sequence of ddx43 in Nile tilapia (Oreochromis niloticus). The ddx43 gene was 2338 bp in length, contained an open reading frame (ORF) of 2064 bp and encoded a polypeptide of 687 amino acids. The predicted protein of OnDDX43 has three conserved domains, including the RNA binding domain KH, DEAD-like helicase superfamily DEXDc and C-terminal HELICc domain. In healthy Nile tilapia, the Onddx43 transcript was broadly expressed in all examined tissues, with the highest expression levels in the muscle and brain and the lowest in the liver. After challenge with Streptococcus agalactiae, lipopolysaccharides (LPS) and polyinosinic polycytidylic acid (Poly I:C), the expression level of Onddx43 mRNA was upregulated or downregulated in all of the tissues tested. Overexpression of OnDDX43 in 293 T cells showed that it has a positive regulatory effect on IFN-β. The subcellular localization showed that OnDDX43 was expressed in the cytoplasm. We performed further pull-down assays and found that OnDDX43 interacted with both interferon-β promoter stimulator1 (IPS-1) and TIR domain-containing adaptor inducing interferon-β (TRIF).
DDX43 是 DExD/H 盒蛋白家族的成员之一，有新数据表明它可能在哺乳动物的抗病毒免疫中发挥重要作用。然而，关于鱼类免疫反应中的 DDX43 知之甚少。在本研究中，我们从尼罗罗非鱼（Oreochromis niloticus）中分离出了 ddx43 的 cDNA 序列。ddx43 基因长 2338bp，含有一个 2064bp 的开放阅读框（ORF），编码一个 687 个氨基酸的多肽。OnDDX43 的预测蛋白含有三个保守结构域，包括 RNA 结合结构域 KH、DEAD 样解旋酶超家族 DEXDc 和 C 端 HELICc 结构域。在健康的尼罗罗非鱼中，Onddx43 转录本广泛表达于所有检测组织，在肌肉和脑中表达量最高，在肝脏中表达量最低。用无乳链球菌、脂多糖（LPS）和多聚肌苷酸多聚胞苷酸（Poly I:C）处理后，所有检测组织中 Onddx43 mRNA 的表达水平均上调或下调。在 293T 细胞中过表达 OnDDX43 表明其对 IFN-β 具有正向调节作用。亚细胞定位表明 OnDDX43 表达于细胞质中。我们进一步进行了下拉实验，发现 OnDDX43 与干扰素-β 启动子刺激因子 1（IPS-1）和 TIR 结构域包含的衔接蛋白诱导干扰素-β（TRIF）相互作用。
