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Novel insights into stress-induced susceptibility to influenza: corticosterone impacts interferon-? responses by Mfn2-mediated ubiquitin degradation of MAVS.

ABSTRACT: Although stress has been known to increase the susceptibility of pathogen infection, the underlying mechanism remains elusive. In this study, we reported that restraint stress dramatically enhanced the morbidity and mortality of mice infected with the influenza virus (H1N1) and obviously aggravated lung inflammation. Corticosterone (CORT), a main type of glucocorticoids in rodents, was secreted in the plasma of stressed mice. We further found that this stress hormone significantly boosted virus replication by restricting mitochondrial antiviral signaling (MAVS) protein-transduced IFN-? production without affecting its mRNA level, while the deficiency of MAVS abrogated stress/CORT-induced viral susceptibility in mice. Mechanistically, the effect of CORT was mediated by proteasome-dependent degradation of MAVS, thereby resulting in the impediment of MAVS-transduced IFN-? generation in vivo and in vitro. Furthermore, RNA-seq assay results indicated the involvement of Mitofusin 2 (Mfn2) in this process. Gain- and loss-of-function experiments indicated that Mfn2 interacted with MAVS and recruited E3 ligase SYVN1 to promote the polyubiquitination of MAVS. Co-immunoprecipitation experiments clarified an interaction between any two regions of Mfn2 (HR1), MAVS (C-terminal/TM) and SYVN1 (TM). Collectively, our findings define the Mfn2-SYVN1 axis as a new signaling cascade for proteasome-dependent degradation of MAVS and a 'fine tuning' of antiviral innate immunity in response to influenza infection under stress.

SUBMITTER: Luo Z

PROVIDER: S-EPMC7499204 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Novel insights into stress-induced susceptibility to influenza: corticosterone impacts interferon-β responses by Mfn2-mediated ubiquitin degradation of MAVS.

Luo Zhuo Z Liu Li-Fang LF Jiang Ying-Nan YN Tang Lu-Ping LP Li Wen W Ouyang Shu-Hua SH Tu Long-Fang LF Wu Yan-Ping YP Gong Hai-Biao HB Yan Chang-Yu CY Jiang Shan S Lu Yu-Hui YH Liu Tongzheng T Jiang Zhenyou Z Kurihara Hiroshi H Yu Yang Y Yao Xin-Sheng XS Li Yi-Fang YF He Rong-Rong RR

Signal transduction and targeted therapy 20200918 1

Although stress has been known to increase the susceptibility of pathogen infection, the underlying mechanism remains elusive. In this study, we reported that restraint stress dramatically enhanced the morbidity and mortality of mice infected with the influenza virus (H1N1) and obviously aggravated lung inflammation. Corticosterone (CORT), a main type of glucocorticoids in rodents, was secreted in the plasma of stressed mice. We further found that this stress hormone significantly boosted virus ...[more]

PMID: 32943610

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Project description:The binding of viral RNA to RIG-I-like receptors triggers the formation of mitochondrial antiviral signaling (MAVS) protein aggregates critical for interferon (IFN) expression. Several rotavirus strains have been shown to suppress IFN expression by inducing MAVS degradation. Relying on transient expression assays, previous studies reached different conclusions regarding the identity of the rotavirus protein responsible for MAVS degradation, suggesting it was an activity of the rotavirus capping enzyme VP3 or the interferon antagonist NSP1. Here, we have used recombinant SA11 rotaviruses to identify the endogenous viral protein responsible for MAVS degradation and to analyze how the attack on MAVS impacts IFN expression. The recombinant viruses included those expressing modified VP3 or NSP1 proteins deficient in the ability to induce the degradation of MAVS or interferon regulatory factor-3 (IRF3), or both. With these viruses, we determined that VP3 directs the proteasomal degradation of MAVS but plays no role in IRF3 degradation. Moreover, NSP1 was determined to induce IRF3 degradation but to have no impact on MAVS degradation. Analysis of rotavirus-infected cells indicated that IRF3 degradation was more efficient than MAVS degradation and that NSP1 was primarily responsible for suppressing IFN expression in infected cells. However, VP3-mediated MAVS degradation contributed to IFN suppression in cells that failed to produce functional NSP1, pointing to a subsidiary role for VP3 in the IFN antagonist activity of NSP1. Thus, VP3 is a multifunctional protein with several activities that counter anti-rotavirus innate immune responses, including capping of viral (+)RNAs, hydrolysis of the RNase L 2-5A (2'-5' oligoadenylate) signaling molecule, and proteasomal degradation of MAVS. IMPORTANCE Rotavirus is an enteric RNA virus that causes severe dehydrating gastroenteritis in infants and young children through infection of enterocytes in the small intestine. Timely clearance of the virus demands a robust innate immune response by cells associated with the small intestine, including the expression of interferon (IFN). Previous studies have shown that some rotavirus strains suppress the production of interferon, by inducing the degradation of mitochondrial antiviral signaling (MAVS) protein and interferon regulatory factor-3 (IRF3). In this study, we have used reverse genetics to generate recombinant rotaviruses expressing compromised forms of VP3 or NSP1, or both, to explore the function of these viral proteins in the degradation of MAVS and IRF3. Our results demonstrate that VP3 is responsible for MAVS depletion in rotavirus-infected cells, and through this activity, helps to suppress IFN production. Thus, VP3 functions to support the activity of rotavirus NSP1, the major interferon antagonist of the virus.

Project description:Rationale: Herpes simplex virus type 1 (HSV-1) is a neurotropic virus that can cause a variety of clinical syndromes including mucocutaneous disease and HSV-1 encephalitis (HSE). Here, we characterize the molecular mechanisms underlying the susceptibility to HSV-1 under stressful conditions. Methods: Restraint stress and corticosterone (CORT, a primary stress hormone) were respectively used to establish HSV-1 susceptible model in vivo and in vitro. Viral titers were determined by plaque assay. Western blotting, immunofluorescence, transmission electron microscopy (TEM), qRT-PCR, H&E staining, IHC staining and flow cytometry were employed to evaluate virus-related protein expressions and detect the activation of autophagy. Loss- and gain-function assays, co-immunoprecipitation (co-IP) technique and autophagy agonist/antagonist treatments were applied in mechanistic experiments. Results: Restraint stress increased the susceptibility of mouse brain to HSV-1. Similarly, CORT treatment enhanced the susceptibility of neural cells to HSV-1. Furthermore, PML protein level in HSV-1 infected brain tissues and neural cells was remarkably decreased by stress treatment in vivo or CORT treatment in vitro, while its transcriptional level was not affected. Notably, a striking decline in protein expressions of ICP27 and gB was observed in PML-overexpressing cells, which was reversed by CORT treatment. By contrast, protein expression of gB was increased by knockdown with si-PML in virus-infected SH-SY5Y cells. We further discovered that CORT-driven PML degradation was dependent on the activation of autophagy in a ULK1-independent manner, rather than proteasome pathway. Bafilomycin A1 (BaF1) attenuated the augmentation effect of CORT on HSV-1 infection. The expressions of viral proteins were reduced in LC3-depleted cells, and the degradation of PML by CORT-induced autophagy was prevented in cells with LC3 knockdown by RNAi. Interestingly, PML was revealed to interact with the autophagic cargo receptor P62 and the autophagic effector protein LC3. Additionally, CORT failed to increase gB protein level when PML was silenced, providing direct evidence linking autophagic degradation of PML and CORT-induced virus susceptibility. Conclusion: Our results revealed that restraint stress/CORT increased HSV-1 susceptibility by delivering PML into autolysosomes for degradation. The results obtained from in vitro and in vivo models not only demonstrated the adverse effects of stress on HSV-1 infection, but also systematically investigated the underlying molecular mechanisms. These discoveries broaden our understanding of the interplay between host and viruses, and a comprehensive understanding of the role of autophagy in viral infection will provide information for future development of innovative drugs against viral infection.

Project description:Tembusu virus (TMUV) is a newly emerged avian flavivirus that has caused severe egg-drop syndrome and fatal encephalitis in domestic ducks. It has spread widely throughout the main duck-producing areas in Asia, resulting in substantial economic losses to the duck industry. Previous studies have reported that TMUV has evolved several strategies to counteract the duck's innate immune responses to successfully establish infection in its host cells. However, the mechanisms underlying this phenomenon have not been elucidated. Here, we discovered that TMUV-encoded NS2B is a negative regulator of poly(I:C)-induced duck interferon-β (IFN-β) expression. Mechanistically, TMUV NS2B was found to interact specifically with the mitochondrial antiviral-signaling protein (duMAVS). Consequently, duMAVS was degraded through the K48-linked ubiquitination and proteasomal pathway, leading to the interruption of the RIG-I-like receptor (RLR) signaling. Further analyses also identified K321, K354, K398, and K411 as crucial residues for NS2B-mediated ubiquitination and degradation of duMAVS. Additionally, we demonstrated that NS2B functions by recruiting the E3 ubiquitin ligase duck membrane-associated RING-CH-type finger 5 (duMARCH5) to modify duMAVS via polyubiquitination, blocking the duMAVS-mediated innate immune response and promoting TMUV replication. Taken together, our findings revealed a novel mechanism by which TMUV evades the duck's antiviral innate immune responses. IMPORTANCE Tembusu virus (TMUV), an emerging pathogenic flavivirus, has spread to most duck farming areas in Asia since 2010, causing significant economic losses to the duck industry. Recently, TMUV has expanded its host range and may pose a potential threat to mammals, including humans. Understanding the interaction between TMUV and its host is essential for the development of effective vaccines and therapeutics. Here, we show that NS2B encoded by TMUV inhibits IFN production by interacting with duck MAVS (duMAVS) to mediate ubiquitination and proteasomal degradation. Further studies suggest that the E3 ubiquitin ligase duck membrane-associated RING-CH-type finger 5 (duMARCH5) is recruited by NS2B to mediate proteasomal degradation of duMAVS. As a result, the innate immune response triggered by the RIG-I-like receptor (RLR) is disrupted, facilitating viral replication. Overall, our results reveal a novel mechanism by which TMUV evades host innate immunity and provide new therapeutic strategies to prevent TMUV infection.

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Dataset Information

Novel insights into stress-induced susceptibility to influenza: corticosterone impacts interferon-? responses by Mfn2-mediated ubiquitin degradation of MAVS.

Publications

Novel insights into stress-induced susceptibility to influenza: corticosterone impacts interferon-β responses by Mfn2-mediated ubiquitin degradation of MAVS.

Similar Datasets

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