Joint Laboratory of Guangdong Province and Hong Kong Regions on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China.
School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China.
Fish Shellfish Immunol. 2019 Apr;87:730-736. doi: 10.1016/j.fsi.2019.02.018. Epub 2019 Feb 12.
Tumor necrosis factor receptor-associated factor 5 (TRAF5) is a key adapter molecule that participates in numerous signaling pathways. The function of TRAF5 in fish is largely unknown. In the present study, a TRAF5 cDNA sequence (EcTRAF5) was identified in grouper (Epinephelus coioides). Similar to its mammalian counterpart, EcTRAF5 contained an N-terminal RING finger domain, a zinc finger domain, a C-terminal TRAF domain, including a coiled-coil domain and a MATH domain. The EcTRAF5 protein shared relatively low sequence identity with that of other species, but clustered with TRAF5 sequences from other fish. Real-time PCR analysis revealed that EcTRAF5 mRNA was broadly expressed in numerous tissues, with relatively high expression in skin, hindgut, and head kidney. Additionally, the expression of EcTRAF5 was up-regulated in gills and head kidney after infection with Cryptocaryon irritans. Intracellular localization analysis demonstrated that the full-length EcTRAF5 protein was uniformly distributed in the cytoplasm; while a deletion mutant of the coiled-coil domain of EcTRAF5 was observed uniformly distributed in the cytoplasm and the nucleus. After exogenous expression in HEK293T cells, TRAF5 significantly activated NF-κB. The deletion of the EcTRAF5 RING domain or of the zinc finger domain dramatically impaired its ability to activate NF-κB, implying that the RING domain and the zinc finger domain are required for EcTRAF5 signaling.
肿瘤坏死因子受体相关因子 5（TRAF5）是一种参与众多信号通路的关键衔接分子。TRAF5 在鱼类中的功能在很大程度上是未知的。在本研究中，从石斑鱼（Epinephelus coioides）中鉴定出一种 TRAF5 cDNA 序列（EcTRAF5）。与哺乳动物的对应物相似，EcTRAF5 包含一个 N 端 RING 指结构域、一个锌指结构域、一个 C 端 TRAF 结构域，包括一个卷曲螺旋结构域和一个 MATH 结构域。EcTRAF5 蛋白与其他物种的序列具有相对较低的序列同一性，但与其他鱼类的 TRAF5 序列聚类。实时 PCR 分析显示 EcTRAF5 mRNA 在许多组织中广泛表达，在皮肤、后肠和头肾中表达较高。此外，EcTRAF5 在感染 Cryptocaryon irritans 后在鳃和头肾中表达上调。细胞内定位分析表明全长 EcTRAF5 蛋白均匀分布在细胞质中；而 EcTRAF5 卷曲螺旋结构域缺失突变体均匀分布在细胞质和细胞核中。在 HEK293T 细胞中外源表达后，TRAF5 显著激活 NF-κB。EcTRAF5 RING 结构域或锌指结构域的缺失极大地削弱了其激活 NF-κB 的能力，表明 RING 结构域和锌指结构域是 EcTRAF5 信号所必需的。
