Tharanga E M T, Nadarajapillai Kishanthini, Warnakula W A D L R, Kim Gaeun, Lim Chaehyeon, Yang Hyerim, Jayasinghe J D H E, Jeyakanesh Jeganathan Tharshan, Sirisena D M K P, Arachchi U P E, Wan Qiang, Lee Jehee
Department of Marine Life Sciences & Center for Genomic Selection in Korean Aquaculture, Jeju National University, Jeju, 63243, Republic of Korea.
Genetics and Breeding Research Center, National Institute of Fisheries Science, Geoje, 53334, Republic of Korea.
Fish Shellfish Immunol. 2025 Feb;157:110089. doi: 10.1016/j.fsi.2024.110089. Epub 2024 Dec 10.
Tumor necrosis factor receptor-associated factor 2 (TRAF2) is a key adaptor molecule in tumor necrosis factor receptor signaling complexes, facilitating downstream immune-related signaling cascades. This study aimed to elucidate its function in teleost fish by characterizing the TRAF2 homolog of the red-spotted grouper (Epinephelus akaara, EaTraf2). The open reading frame of EaTraf2 encodes a putative protein of 520 amino acids, containing several characteristic domains of TRAF2. These structural features of EaTraf2 are conserved across diverse organisms, with a relatively higher sequence identity to TRAF2 orthologs from other bony fish. Transcriptional analysis demonstrated that EaTraf2 was ubiquitously expressed in all examined tissues, with the highest level observed in blood. Upon immune challenge, EaTraf2 expression significantly increased in the early stages of stimulation in both blood and spleen. Subcellular localization analysis revealed that EaTraf2 is predominantly localized in the cytoplasm. Overexpression of EaTraf2 in fathead minnow (FHM) cells resulted in elevated levels of interferon and inflammation-associated genes following viral hemorrhagic septicemia virus (VHSV) infection, along with reduced viral gene expression. This provided compelling evidence that EaTraf2 possesses antiviral properties. Furthermore, EaTraf2 demonstrated the ability to promote cell death induced by oxidative stress. Additionally, luciferase reporter assays revealed that EaTraf2 activates the NF-κB signaling pathway upon poly(I:C) stimulation and the Jun N-terminal kinase (JNK) signaling pathway in response to HO treatment. Overall, our study elucidated the role of EaTraf2 in regulating innate immune responses and mediating stress-induced cell death. These findings enhance our understanding of TRAF2 in fish and may contribute to improved health management strategies in finfish aquaculture.
肿瘤坏死因子受体相关因子2（TRAF2）是肿瘤坏死因子受体信号复合物中的关键衔接分子，可促进下游免疫相关信号级联反应。本研究旨在通过表征红斑石斑鱼（Epinephelus akaara，EaTraf2）的TRAF2同源物来阐明其在硬骨鱼中的功能。EaTraf2的开放阅读框编码一个推定的520个氨基酸的蛋白质，包含TRAF2的几个特征结构域。EaTraf2的这些结构特征在不同生物中保守，与其他硬骨鱼的TRAF2直系同源物具有相对较高的序列同一性。转录分析表明，EaTraf2在所有检测组织中普遍表达，在血液中表达水平最高。免疫刺激后，血液和脾脏在刺激早期EaTraf2表达显著增加。亚细胞定位分析显示，EaTraf2主要定位于细胞质中。在黑头呆鱼（FHM）细胞中过表达EaTraf2导致在感染病毒性出血性败血症病毒（VHSV）后干扰素和炎症相关基因水平升高，同时病毒基因表达降低。这提供了有力证据表明EaTraf2具有抗病毒特性。此外，EaTraf2表现出促进氧化应激诱导的细胞死亡的能力。另外，荧光素酶报告基因检测显示，EaTraf2在聚肌苷酸:聚胞苷酸（poly(I:C)）刺激下激活核因子κB（NF-κB）信号通路，并在过氧化氢（HO）处理后激活Jun氨基末端激酶（JNK）信号通路。总体而言，我们的研究阐明了EaTraf2在调节先天免疫反应和介导应激诱导的细胞死亡中的作用。这些发现增进了我们对鱼类中TRAF2的理解，并可能有助于改进硬骨鱼养殖中的健康管理策略。
