RESUMEN
Interferon (IFN)-stimulated gene 15 (ISG15), a ubiquitin-like protein, is covalently conjugated to host immune proteins such as MDA5 and IRF3 in a process called ISGylation, thereby promoting type I IFN induction to limit the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, whether SARS-CoV-2 proteins can be directly targeted for ISGylation remains elusive. In this study, we identified the nucleocapsid (N) protein of SARS-CoV-2 as a major substrate of ISGylation catalyzed by the host E3 ligase HERC5; however, N ISGylation is readily removed through deISGylation by the papain-like protease (PLpro) activity of NSP3. Mass spectrometry analysis identified that the N protein undergoes ISGylation at four lysine residues (K266, K355, K387, and K388), and mutational analysis of these sites in the context of a SARS-CoV-2 replicon (N-4KR) abolished N ISGylation and alleviated ISGylation-mediated inhibition of viral RNA synthesis. Furthermore, our results indicated that HERC5 targets preferentially phosphorylated N protein for ISGylation to regulate its oligomeric assembly. These findings reveal a novel mechanism by which the host ISGylation machinery directly targets SARS-CoV-2 proteins to restrict viral replication and illuminate how an intricate interplay of host (HERC5) and viral (PLpro) enzymes coordinates viral protein ISGylation and thereby regulates virus replication.IMPORTANCEThe role of protein ISGylation in regulating host cellular processes has been studied extensively; however, how ISG15 conjugation influences the activity of viral proteins, particularly coronaviral proteins, is largely unknown. Our study uncovered that the nucleocapsid (N) protein of SARS-CoV-2 is ISGylated by the HERC5 ISGylation machinery and that this modification impedes the functional assembly of N into oligomers ultimately inhibiting viral RNA synthesis. This antiviral restriction mechanism is antagonized by the PLpro deISGylation activity of SARS-CoV-2 NSP3. This study deepens our understanding of SARS-CoV-2 protein regulation by posttranslational modifications and may open new avenues for designing antiviral strategies for COVID-19.
RESUMEN
Interferon (IFN)-stimulated gene 15 (ISG15), a ubiquitin-like protein, is covalently conjugated to host (immune) proteins such as MDA5 and IRF3 in a process called ISGylation, thereby limiting the replication of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, whether SARS-CoV-2 proteins can be directly targeted for ISGylation remains elusive. In this study, we identified the nucleocapsid (N) protein of SARS-CoV-2 as a major substrate of ISGylation catalyzed by the host E3 ligase HERC5; however, N ISGylation is readily removed through de-ISGylation by the papain-like protease (PLpro) activity of NSP3. Mass spectrometry analysis identified that the N protein undergoes ISGylation at four lysine residues (K266, K355, K387 and K388), and mutational analysis of these sites in the context of a SARS-CoV-2 replicon (N-4KR) abolished N ISGylation and alleviated ISGylation-mediated inhibition of viral RNA synthesis. Furthermore, our results indicated that HERC5 targets preferentially phosphorylated N protein for ISGylation to regulate its oligomeric assembly. These findings reveal a novel mechanism by which the host ISGylation machinery directly targets SARS-CoV-2 proteins to restrict viral replication and illuminate how an intricate interplay of host (HERC5) and viral (PLpro) enzymes coordinates viral protein ISGylation and thereby regulates virus replication.
RESUMEN
Viral myocarditis, an inflammatory disease of the heart, causes significant morbidity and mortality. Type I interferon (IFN)-mediated antiviral responses protect against myocarditis, but the mechanisms are poorly understood. We previously identified A Disintegrin And Metalloproteinase domain 9 (ADAM9) as an important factor in viral pathogenesis. ADAM9 is implicated in a range of human diseases, including inflammatory diseases; however, its role in viral infection is unknown. Here, we demonstrate that mice lacking ADAM9 are more susceptible to encephalomyocarditis virus (EMCV)-induced death and fail to mount a characteristic type I IFN response. This defect in type I IFN induction is specific to positive-sense, single-stranded RNA (+ ssRNA) viruses and involves melanoma differentiation-associated protein 5 (MDA5)-a key receptor for +ssRNA viruses. Mechanistically, ADAM9 binds to MDA5 and promotes its oligomerization and thereby downstream mitochondrial antiviral-signaling protein (MAVS) activation in response to EMCV RNA stimulation. Our findings identify a role for ADAM9 in the innate antiviral response, specifically MDA5-mediated IFN production, which protects against virus-induced cardiac damage, and provide a potential therapeutic target for treatment of viral myocarditis.
Asunto(s)
Proteínas ADAM , Infecciones por Cardiovirus , Virus de la Encefalomiocarditis , Inmunidad Innata , Interferón Tipo I , Helicasa Inducida por Interferón IFIH1 , Proteínas de la Membrana , Miocarditis , Animales , Ratones , Proteínas ADAM/metabolismo , Proteínas ADAM/genética , Proteínas ADAM/inmunología , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/inmunología , Infecciones por Cardiovirus/inmunología , Infecciones por Cardiovirus/virología , Virus de la Encefalomiocarditis/inmunología , Células HEK293 , Interferón Tipo I/metabolismo , Interferón Tipo I/inmunología , Helicasa Inducida por Interferón IFIH1/metabolismo , Helicasa Inducida por Interferón IFIH1/genética , Helicasa Inducida por Interferón IFIH1/inmunología , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/inmunología , Ratones Endogámicos C57BL , Ratones Noqueados , Miocarditis/inmunología , Miocarditis/virología , Transducción de Señal/inmunologíaRESUMEN
The RIG-I-like receptors (RLRs), RIG-I and MDA5, are innate sensors of RNA virus infections that are critical for mounting a robust antiviral immune response. We have shown previously that HOIL1, a component of the Linear Ubiquitin Chain Assembly Complex (LUBAC), is essential for interferon (IFN) induction in response to viruses sensed by MDA5, but not for viruses sensed by RIG-I. LUBAC contains two unusual E3 ubiquitin ligases, HOIL1 and HOIP. HOIP generates methionine-1-linked polyubiquitin chains, whereas HOIL1 has recently been shown to conjugate ubiquitin onto serine and threonine residues. Here, we examined the differential requirement for HOIL1 and HOIP E3 ligase activities in RLR-mediated IFN induction. We determined that HOIL1 E3 ligase activity was critical for MDA5-dependent IFN induction, while HOIP E3 ligase activity played only a modest role in promoting IFN induction. HOIL1 E3 ligase promoted MDA5 oligomerization, its translocation to mitochondrial-associated membranes, and the formation of MAVS aggregates. We identified that HOIL1 can interact with and facilitate the ubiquitination of LGP2, a positive regulator of MDA5 oligomerization. In summary, our work identifies LGP2 ubiquitination by HOIL1 in facilitating the activation of MDA5 and the induction of a robust IFN response.
RESUMEN
Activation of type I interferon (IFN-1) signaling is essential to protect host cells from viral infection. The full spectrum of IFN-I induction requires the activation of a number of cellular factors, including IκB kinase epsilon (IKKϵ). However, the regulation of IKKϵ activation in response to viral infection remains largely unknown. Here, we show that factor inhibiting hypoxia-inducible factor (HIF) (FIH), an asparaginyl hydroxylase, interacts with IKKϵ and catalyzes asparagine hydroxylation of IKKϵ at Asn-254, Asn-700, and Asn-701, resulting in the suppression of IKKϵ activation. FIH-mediated hydroxylation of IKKϵ prevents IKKϵ binding to TBK1 and TRAF3 and attenuates the cIAP1/cIAP2/TRAF2 E3 ubiquitin ligase complex-catalyzed K63-linked polyubiquitination of IKKϵ at Lys-416. In addition, Fih-deficient mice and zebrafish are more resistant to viral infection. This work uncovers a previously unrecognized role of FIH in suppressing IKKϵ activation for IFN signaling and antiviral immune responses.
Asunto(s)
Quinasa I-kappa B , Virosis , Animales , Ratones , Quinasa I-kappa B/metabolismo , Proteínas Represoras/metabolismo , Secuencia de Aminoácidos , Hidroxilación , Pez Cebra/metabolismo , Inmunidad InnataRESUMEN
Hepatitis C virus (HCV) is a significant human pathogen that can cause a number of serious diseases including chronic inflammation of the liver, cirrhosis, and hepatocellular carcinoma. A key enzyme in the HCV life cycle is the nonstructural protein 5B (NS5B), which functions as an RNA-dependent RNA polymerase (RdRp) responsible for replicating the viral RNA genome. In their recent study, Dansako and colleagues showed that HCV NS5B induces type I interferon via activation of the RNA receptor MDA5, an activity that was dependent on the RdRp enzymatic activity but independent of viral RNA replication. Their data further indicated that the NS5B enzymes of HCV and the related GB virus-B produce cellular double-stranded RNA (dsRNA) species with potential immunostimulatory activity. These findings unveil an unconventional mechanism of activation of MDA5-mediated host immunity by viral RdRp enzymes, which is expected to spur new research directions in viral immunology.
Asunto(s)
Hepacivirus , Hepatitis C , Humanos , Hepacivirus/genética , ARN Polimerasa Dependiente del ARN/genética , ARN Viral/metabolismo , ARN Bicatenario/metabolismo , Proteínas no Estructurales Virales/genética , Replicación ViralRESUMEN
The cytosolic RNA and DNA sensors initiate type I interferon signaling when binding to RNA or DNA. To effectively protect the host against virus infection and concomitantly avoid excessive interferonopathy at resting states, these sensors must be tightly regulated. However, the key molecular mechanisms regulating these sensors' activation remain elusive. Here, we identify PRMT3, a type I protein arginine methyltransferase, as a negative regulator of cytosolic RNA and DNA sensors. PRMT3 interacts with RIG-I, MDA5, and cGAS and catalyzes asymmetric dimethylation of R730 on RIG-I, R822 on MDA5, and R111 on cGAS. These modifications reduce RNA-binding ability of RIG-I and MDA5 as well as DNA-binding ability and oligomerization of cGAS, leading to the inhibition of downstream type I interferon production. Furthermore, mice with loss of one copy of Prmt3 or in vivo treatment of the PRMT3 inhibitor, SGC707, are more resistant to RNA and DNA virus infection. Our findings reveal an essential role of PRMT3 in the regulation of antiviral innate immunity and give insights into the molecular regulation of cytosolic RNA and DNA sensors' activation.
Asunto(s)
Arginina , Interferón Tipo I , Animales , Ratones , ARN/genética , Antivirales/farmacología , Inmunidad Innata , ADN/genética , Nucleotidiltransferasas/genética , Proteína-Arginina N-Metiltransferasas/genéticaRESUMEN
Re-emerging and new viral pathogens have caused significant morbidity and mortality around the world, as evidenced by the recent monkeypox, Ebola and Zika virus outbreaks and the ongoing COVID-19 pandemic. Successful viral infection relies on tactical viral strategies to derail or antagonize host innate immune defenses, in particular the production of type I interferons (IFNs) by infected cells. Viruses can thwart intracellular sensing systems that elicit IFN gene expression (that is, RIG-I-like receptors and the cGAS-STING axis) or obstruct signaling elicited by IFNs. In this Cell Science at a Glance article and the accompanying poster, we review the current knowledge about the major mechanisms employed by viruses to inhibit the activity of intracellular pattern-recognition receptors and their downstream signaling cascades leading to IFN-based antiviral host defenses. Advancing our understanding of viral immune evasion might spur unprecedented opportunities to develop new antiviral compounds or vaccines to prevent viral infectious diseases.
Asunto(s)
COVID-19 , Interferón Tipo I , Infección por el Virus Zika , Virus Zika , Humanos , Pandemias , Antivirales , Evasión InmuneRESUMEN
Retinoic acid-inducible-I (RIG-I), melanoma differentiation-associated gene 5 (MDA5), and cyclic GMP-AMP synthase (cGAS) genes encode essential cytosolic receptors mediating antiviral immunity against viruses. Here, we show that OTUD3 has opposing role in response to RNA and DNA virus infection by removing distinct types of RIG-I/MDA5 and cGAS polyubiquitination. OTUD3 binds to RIG-I and MDA5 and removes K63-linked ubiquitination. This serves to reduce the binding of RIG-I and MDA5 to viral RNA and the downstream adaptor MAVS, leading to the suppression of the RNA virus-triggered innate antiviral responses. Meanwhile, OTUD3 associates with cGAS and targets at Lys279 to deubiquitinate K48-linked ubiquitination, resulting in the enhancement of cGAS protein stability and DNA-binding ability. As a result, Otud3-deficient mice and zebrafish are more resistant to RNA virus infection but are more susceptible to DNA virus infection. These findings demonstrate that OTUD3 limits RNA virus-triggered innate immunity but promotes DNA virus-triggered innate immunity.
Asunto(s)
Infecciones por Virus ADN , Inmunidad Innata , Infecciones por Virus ARN , Proteasas Ubiquitina-Específicas , Animales , Proteína 58 DEAD Box/metabolismo , Infecciones por Virus ADN/inmunología , Virus ADN , Enzimas Desubicuitinizantes , Helicasa Inducida por Interferón IFIH1/metabolismo , Ratones , Nucleotidiltransferasas , Infecciones por Virus ARN/inmunología , Virus ARN , ARN Viral/metabolismo , Proteasas Ubiquitina-Específicas/metabolismo , Pez Cebra/metabolismoRESUMEN
Some protein-protein interactions are induced by different kinds of stimulation and are dependent on specific genes. To identify these interaction partners, we present a protocol which utilizes affinity purification of Flag-tagged protein complexes followed by mass-spectrometry-based proteomics to compare stimulation-induced interactomes between wild-type and CRISPR-Cas9-mediated knockout cells. The candidates of interest are identified using bioinformatic analyses and verified by biochemical approaches. This protocol is highly versatile and applies to a variety of cells and different types of stimulation. For complete details on the use and execution of this protocol, please refer to (Zhu et al., 2021).
Asunto(s)
Espectrometría de Masas/métodos , Mapeo de Interacción de Proteínas/métodos , Proteínas , Proteómica/métodos , Técnicas de Cultivo de Célula , Células HEK293 , Humanos , Proteínas/análisis , Proteínas/química , Proteínas/metabolismoRESUMEN
Sirt7 is one member of the sirtuin family proteins with NAD (NAD+)-dependent histone deacetylase activity. In this study, we report that zebrafish sirt7 is induced upon viral infection, and overexpression of sirt7 suppresses cellular antiviral responses. Disruption of sirt7 in zebrafish increases the survival rate upon spring viremia of carp virus infection. Further assays indicate that sirt7 interacts with irf3 and irf7 and attenuates phosphorylation of irf3 and irf7 by preventing tbk1 binding to irf3 and irf7. In addition, the enzymatic activity of sirt7 is not required for sirt7 to repress IFN-1 activation. To our knowledge, this study provides novel insights into sirt7 function and sheds new light on the regulation of irf3 and irf7 by attenuating phosphorylation.
Asunto(s)
Carpas , Pez Cebra , Animales , Antivirales , Carpas/metabolismo , Factor 3 Regulador del Interferón/metabolismo , Factores Reguladores del Interferón/metabolismo , NAD/metabolismo , Fosforilación , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismoRESUMEN
TNFR-associated factor 6 (TRAF6) not only recruits TBK1/IKKε to MAVS upon virus infection but also catalyzes K63-linked polyubiquitination on substrate or itself, which is critical for NEMO-dependent and -independent TBK1/IKKε activation, leading to the production of type I IFNs. The regulation at the TRAF6 level could affect the activation of antiviral innate immunity. In this study, we demonstrate that zebrafish prmt2, a type I arginine methyltransferase, attenuates traf6-mediated antiviral response. Prmt2 binds to the C terminus of traf6 to catalyze arginine asymmetric dimethylation of traf6 at arginine 100, preventing its K63-linked autoubiquitination, which results in the suppression of traf6 activation. In addition, it seems that the N terminus of prmt2 competes with mavs for traf6 binding and prevents the recruitment of tbk1/ikkε to mavs. By zebrafish model, we show that loss of prmt2 promotes the survival ratio of zebrafish larvae after challenge with spring viremia of carp virus. Therefore, we reveal, to our knowledge, a novel function of prmt2 in the negative regulation of antiviral innate immunity by targeting traf6.
Asunto(s)
Inmunidad Innata/inmunología , Proteína-Arginina N-Metiltransferasas/inmunología , Infecciones por Rhabdoviridae/inmunología , Factor 6 Asociado a Receptor de TNF/inmunología , Animales , Rhabdoviridae/inmunología , Pez CebraRESUMEN
Accurate control of innate immune responses is required to eliminate invading pathogens and simultaneously avoid autoinflammation and autoimmune diseases. Here, we demonstrate that arginine monomethylation precisely regulates the mitochondrial antiviral-signaling protein (MAVS)-mediated antiviral response. Protein arginine methyltransferase 7 (PRMT7) forms aggregates to catalyze MAVS monomethylation at arginine residue 52 (R52), attenuating its binding to TRIM31 and RIG-I, which leads to the suppression of MAVS aggregation and subsequent activation. Upon virus infection, aggregated PRMT7 is disabled in a timely manner due to automethylation at arginine residue 32 (R32), and SMURF1 is recruited to PRMT7 by MAVS to induce proteasomal degradation of PRMT7, resulting in the relief of PRMT7 suppression of MAVS activation. Therefore, we not only reveal that arginine monomethylation by PRMT7 negatively regulates MAVS-mediated antiviral signaling in vitro and in vivo but also uncover a mechanism by which PRMT7 is tightly controlled to ensure the timely activation of antiviral defense.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Arginina/metabolismo , Interacciones Huésped-Patógeno/fisiología , Inmunidad Innata/fisiología , Proteína-Arginina N-Metiltransferasas/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/inmunología , Animales , Proteína 58 DEAD Box/metabolismo , Fibroblastos/virología , Células HEK293 , Herpes Simple/inmunología , Herpes Simple/metabolismo , Herpes Simple/virología , Humanos , Metilación , Ratones , Ratones Noqueados , Alcamidas Poliinsaturadas , Proteína-Arginina N-Metiltransferasas/antagonistas & inhibidores , Proteína-Arginina N-Metiltransferasas/genética , Proteína-Arginina N-Metiltransferasas/inmunología , Receptores Inmunológicos/metabolismo , Infecciones por Respirovirus/inmunología , Infecciones por Respirovirus/metabolismo , Infecciones por Respirovirus/virología , Proteínas de Motivos Tripartitos/genética , Proteínas de Motivos Tripartitos/metabolismo , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Ovarian tumor domain-containing 6B (OTUD6B) belongs to the OTU deubiquitylating enzyme family. In this study, we report that zebrafish otud6b is induced upon viral infection, and overexpression of otud6b suppresses cellular antiviral response. Disruption of otud6b in zebrafish increases the survival rate upon spring viremia of carp virus and grass carp reovirus exposure. Further assays indicate that otud6b interacts with irf3 and irf7 and diminishes traf6-mediated K63-linked polyubiquitination of irf3 and irf7. In addition, the OTU domain is required for otud6b to repress IFN-1 activation and K63-linked polyubiquitination of irf3 and irf7. Moreover, otud6b also attenuates tbk1 to bind to irf3 and irf7, resulting in the impairment of irf3 and irf7 phosphorylation. This study provides, to our knowledge, novel insights into otud6b function and sheds new lights on the regulation of irf3 and irf7 by deubiquitination in IFN-1 signaling.
Asunto(s)
Carpas/inmunología , Factor 3 Regulador del Interferón/inmunología , Factores Reguladores del Interferón/inmunología , Lisina/inmunología , Viremia/inmunología , Proteínas de Pez Cebra/inmunología , Animales , Carpas/virología , Línea Celular , Ubiquitinación , Viremia/virología , Pez Cebra , Proteínas de Pez Cebra/genéticaRESUMEN
The hypoxia-inducible factors 1α and 2α (HIF1α and HIF2α) are master regulators of the cellular response to O2. In addition to HIF1α and HIF2α, HIF3α is another identified member of the HIFα family. Even though the question of whether some HIF3α isoforms have transcriptional activity or repressive activity is still under debate, it is evident that the full length of HIF3α acts as a transcription factor. However, its function in hypoxia signaling is largely unknown. Here, we show that loss of hif3a in zebrafish reduced hypoxia tolerance. Further assays indicated that erythrocyte number was decreased because red blood cell maturation was impeded by hif3a disruption. We found that gata1 expression was downregulated in hif3a null zebrafish, as were several hematopoietic marker genes, including alas2, band3, hbae1, hbae3 and hbbe1 Hif3α recognized the hypoxia response element located in the promoter of gata1 and directly bound to the promoter to transactivate gata1 expression. Our results suggested that hif3a facilities hypoxia tolerance by modulating erythropoiesis via gata1 regulation.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/metabolismo , Eritrocitos/metabolismo , Eritropoyesis , Factor de Transcripción GATA1/metabolismo , Hipoxia/metabolismo , Proteínas de Pez Cebra/metabolismo , Pez Cebra/metabolismo , Animales , Antígenos de Diferenciación/biosíntesis , Antígenos de Diferenciación/genética , Proteínas Reguladoras de la Apoptosis/genética , Regulación hacia Abajo , Eritrocitos/patología , Factor de Transcripción GATA1/genética , Hipoxia/genética , Hipoxia/patología , Elementos de Respuesta , Pez Cebra/genética , Proteínas de Pez Cebra/genéticaRESUMEN
Arginine methylation catalyzed by protein arginine methyltransferases (PRMT) is a common post-translational modification in histone and nonhistone proteins, which regulates many cellular functions. Protein arginine methyltransferase 3 (prmt3), a type I arginine methyltransferase, has been shown to carry out the formation of stable monomethylarginine as an intermediate before the establishment of asymmetric dimethylarginine. To date, however, the role of PRMT3 in antiviral innate immunity has not been elucidated. This study showed that zebrafish prmt3 was upregulated by virus infection and that the overexpression of prmt3 suppressed cellular antiviral response. The PRMT3 inhibitor, SGC707, enhanced antiviral capability. Consistently, prmt3-null zebrafish were more resistant to Spring Viremia of Carp Virus (SVCV) and Grass Carp Reovirus (GCRV) infection. Further assays showed that the overexpression of prmt3 diminished the phosphorylation of irf3 and prmt3 interacted with rig-i. In addition, both zinc-finger domain and catalytic domain of prmt3 were required for the suppressive function of prmt3 on IFN activation. Our findings suggested that zebrafish prmt3 negatively regulated the antiviral responses, implicating the vital role of prmt3-or even arginine methylation-in antiviral innate immunity.
Asunto(s)
Antivirales/inmunología , Proteína-Arginina N-Metiltransferasas/genética , Proteína-Arginina N-Metiltransferasas/inmunología , Pez Cebra/genética , Pez Cebra/inmunología , Animales , Células Cultivadas , Histonas/genética , Histonas/inmunología , Inmunidad Innata/genética , Inmunidad Innata/inmunología , Isoquinolinas/inmunología , Metilación , Fosforilación/genética , Fosforilación/inmunología , Procesamiento Proteico-Postraduccional/genética , Procesamiento Proteico-Postraduccional/inmunología , Rhabdoviridae/inmunología , Infecciones por Rhabdoviridae/genética , Infecciones por Rhabdoviridae/inmunología , Regulación hacia Arriba/genética , Regulación hacia Arriba/inmunología , Virosis/genética , Virosis/inmunología , Virosis/virología , Pez Cebra/virología , Dedos de Zinc/genética , Dedos de Zinc/inmunologíaRESUMEN
RLR-mediated type I IFN production plays a pivotal role in innate antiviral immune responses, where the signaling adaptor MAVS is a critical determinant. Here, we show that MAVS is a physiological substrate of SIRT5. Moreover, MAVS is succinylated upon viral challenge, and SIRT5 catalyzes desuccinylation of MAVS. Mass spectrometric analysis indicated that Lysine 7 of MAVS is succinylated. SIRT5-catalyzed desuccinylation of MAVS at Lysine 7 diminishes the formation of MAVS aggregation after viral infection, resulting in the inhibition of MAVS activation and leading to the impairment of type I IFN production and antiviral gene expression. However, the enzyme-deficient mutant of SIRT5 (SIRT5-H158Y) loses its suppressive role on MAVS activation. Furthermore, we show that Sirt5-deficient mice are resistant to viral infection. Our study reveals the critical role of SIRT5 in limiting RLR signaling through desuccinylating MAVS.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Agregado de Proteínas , Sirtuinas/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Sustitución de Aminoácidos , Animales , Regulación de la Expresión Génica , Células HCT116 , Células HEK293 , Humanos , Interferón Tipo I/biosíntesis , Interferón Tipo I/genética , Ratones , Ratones Noqueados , Mutación Missense , Sirtuinas/genéticaRESUMEN
Transcriptional programs regulated by the NF-κB family are essential for the inflammatory response as well as for innate and adaptive immunity. NF-κB activation occurs via two major signaling pathways: the canonical and the noncanonical. The canonical NF-κB pathway responds to diverse immune stimulations and leads to rapid but transient activation. As a member of the canonical NF-κB family, p65 is thought to be a key regulator of viral infection. Because of the embryonic lethality of p65-null mice, the physiological role of p65 in the antiviral immune response is still unclear. In this study, we generated p65-null zebrafish, which were viable and indistinguishable from their wildtype (WT) siblings under normal conditions. However, p65-null zebrafish were more sensitive to spring viremia of carp virus infection than their WT siblings. Further assays indicated that proinflammatory and antiviral genes, including IFN, were downregulated in p65-null zebrafish after spring viremia of carp virus infection compared with their WT siblings. Our results thus suggested that p65 is required for the antiviral response, activating not only proinflammatory genes but also antiviral genes (including IFN).