Mandarin fish von Hippel-Lindau protein regulates the NF-κB signaling pathway via interaction with IκB to promote fish ranavirus replication
Zhimin Li, 中山大学海洋科学学院水产动物疫病防控与健康养殖全国重点实验室, 南方海洋科学与工程广东省实验室 (珠海), 广东省伶仃洋海洋牧场野外科学观测研究站, 广东 广州 510275, 中国, Xiao-Wei Qin, Qi Zhang, Jian He, Mincong Liang, Chuanrui Li, Yang Yu, Weng-Hui Liu, Shaoping Weng, Jian-Guo He, Changjun Guo, 岭南现代农业科学与技术广东省实验室, 广东 广州 510640, 中国
Abstract
The von Hippel-Lindau tumor suppressor protein (VHL), an E3 ubiquitin ligase, functions as a critical regulator of the oxygen-sensing pathway for targeting hypoxia-inducible factors. Recent evidence suggests that mammalian VHL may also be critical to the NF-κB signaling pathway, although the specific molecular mechanisms remain unclear. Herein, the roles of mandarin fish (<italic>Siniperca chuatsi</italic>) VHL (<italic>sc</italic>VHL) in the NF-κB signaling pathway and mandarin fish ranavirus (MRV) replication were explored. The transcription of <italic>sc</italic>VHL was induced by immune stimulation and MRV infection, indicating a potential role in innate immunity. Dual-luciferase reporter gene assays and reverse transcription quantitative PCR (RT-qPCR) results demonstrated that <italic>sc</italic>VHL evoked and positively regulated the NF-κB signaling pathway. Treatment with NF-κB signaling pathway inhibitors indicated that the role of <italic>sc</italic>VHL may be mediated through <italic>sc</italic>IKKα, <italic>sc</italic>IKKβ, <italic>sc</italic>IκBα, or <italic>sc</italic>p65. Co-immunoprecipitation (Co-IP) analysis identified <italic>sc</italic>IκBα as a novel target protein of <italic>sc</italic>VHL. Moreover, <italic>sc</italic>VHL targeted <italic>sc</italic>IκBα to catalyze the formation of K63-linked polyubiquitin chains to activate the NF-κB signaling pathway. Following MRV infection, NF-κB signaling remained activated, which, in turn, promoted MRV replication. These findings suggest that <italic>sc</italic>VHL not only positively regulates NF-κB but also significantly enhances MRV replication. This study reveals a novel function of <italic>sc</italic>VHL in NF-κB signaling and viral infection in fish.