E3 Ubiquitin Ligase RNF114 Inhibits Innate Immune Response to Red-Spotted Grouper Nervous Necrosis Virus Infection in Sea Perch by Targeting MAVS and TRAF3 to Mediate Their Degradation

Abstract

RIG-I–like receptor (RLR)–mediated antiviral signaling is critical to trigger the immune response to virus infection; however, the antiviral responses are also tightly regulated to avoid uncontrolled production of type I IFN by various mechanisms, including ubiquitination. In this study, an E3 ubiquitin ligase ring finger protein 114 (RNF114) from sea perch (Lateolabrax japonicus) (LjRNF114) was identified as a suppressor of RLR signaling pathways during red-spotted grouper nervous necrosis virus (RGNNV) infection. RGNNV infection promoted the expression of LjRNF114. Overexpression of LjRNF114 enhanced RGNNV replication, whereas knockdown of LjRNF114 led to opposite effects. Type I IFN production induced by RGNNV was suppressed by LjRNF114, which is dependent on its ubiquitin ligase activity. Moreover, LjRNF114 inhibited IFN promoter activation induced by key signaling molecules in RLR signaling pathways. We observed the interactions between LjRNF114 and both sea perch mitochondrial antiviral signaling protein (MAVS) and TNFR-associated factor 3 (TRAF3). Domain mapping experiments indicated that the RING and ubiquitin interacting motif domains of LjRNF114 were required for its interaction with TRAF3 and MAVS. We found that LjRNF114 targeted MAVS and TRAF3 for K27- and K48-linked ubiquitination and degradation, resulting in the inhibition of IFN production. Taken together, our study reveals, to our knowledge, a novel mechanism that LjRNF114 targets and promotes K27- and K48-linked ubiquitination of MAVS and TRAF3 to negatively regulate the RLR signaling pathways, promoting viral infection.

The RING finger protein family in health and disease

“…Several studies also identified that the RNF114/LjRNF114 directly associates with MAVS and targets it for proteasomal degradation via K27-linked ubiquitination to inhibit RLR-mediated antiviral signaling. 243 , 244 However, Rnf114 −/− mice failed to display enhanced resistance to RNA virus infection. Based on the above findings, further investigation is needed to determine the paradoxical roles of RNF114 in RLR signaling pathways.…”

“…A recent study, controversial to a previous study, revealed that the LjRNF114, RNF114 from Lateolabrax japonicus , interacts with TRAF3 and transfers the K48-linked ubiquitination to TRAF3 for proteasomal degradation to modulate the RLR-mediated antiviral signaling negatively. 236 , 243 Interestingly, their study also indicated that Red-Spotted grouper nervous necrosis virus (RGNNV) infection enhances the expression of LjRNF114, suppressing the RLR-dependent IFN production, thus potentiating the RGNNV replication in a positive feedback manner. This report provided a potential target at LjRNF114 for a prospective therapeutic strategy against nervous necrosis virus infection, which causes more than 90% mortality in the larval stage of fish.…”

MST4 negatively regulates type I interferons production via targeting MAVS-mediated pathway

“…Multiple molecules act as negative regulators of type I IFN production by regulating the stability of MAVS along with the formation of the MAVS/TRAF3 complex in a variety of manners. For instance, the E3 ubiquitin ligase RNF114 inhibits the innate immune response against the red-spotted grouper nervous necrosis viral infection by targeting the interaction between TRAF3 and MAVS in sea perch [ 10 ]. The hereditary hemochromatosis protein HFE inhibits the production of type I IFN signaling by targeting the SQSTM1-mediated autophagic degradation of MAVS [ 11 ].…”

Establishment and characterization of a liver cell line, ALL, derived from yellowfin sea bream, Acanthopagrus latus, and its application to fish virology

“…As an excellent in vitro platform, fish cell lines have been widely applied to the study of virology, immunology, toxicology, preservation of germplasm resources, gene screening and functional analysis (Collet et al., 2018; Liu et al., 2020; Ruiz‐Palacios et al., 2020). For instance, fathead minnow (FHM) cell line was applied to the propagation of multiple fish viruses, including viral haemorrhagic septicaemia virus (VHSV), nervous necrosis virus (NNV) and infectious pancreatic necrosis virus (Huang et al., 2018; Lorenzen et al., 1999; Zhang, Li, et al., 2019); Lateolabrax japonicus brain cell line, derived from the brain of sea perch, was used for studying the interaction between NNV and sea perch (Jia et al., 2016; Xiang et al., 2021); and Fundulus heteroclitus brain cell line, pearl gentian grouper gill cell line and Trachinotus ovatus kidney cell line were applied to investigate the toxicity of PS‐100, Cd, Cu and Hg, respectively (Ruiz‐Palacios et al., 2020; Xu et al., 2021; Zhou et al., 2017). Since the establishment of the first fish cell line RTG‐2 in 1962, more than 880 fish cell lines have been established to date (Robin et al., 2020; Wolf & Quimby, 1962).…”