Alphavirus infection triggers antiviral RNAi immunity in mammals
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ABSTRACT:
PROVIDER: PRJNA885440 | ENA |
REPOSITORIES: ENA
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Project description:RNA interference (RNAi) functions as an antiviral immune response in plants and invertebrates, whereas mammalian RNAi response has been found so far only in undifferentiated cells and in differentiated cells inactive in interferon (IFN) system or in infections with viruses disabling viral suppressors of RNAi (VSRs), thereby leading to question the physiological importance of the RNAi pathway in mammals. Here, we identified that wild-type Semliki Forest virus (SFV), a prototypic alphavirus, triggered the Dicer-dependent production of abundant viral (v)siRNAs in different mammalian somatic cells in the presence of VSR. These vsiRNAs were produced from viral dsRNA replicative intermediates, almost exclusively located at the 5’ termini of the viral genome, and loaded into AGO, and they were fully active in slicing cognate viral RNAs. Besides, Sindbis virus, another alphavirus, also induced vsiRNA generation in mammalian somatic cells. AGO2 deficiency increased SFV and SINV replication, while enoxacin, a known RNAi enhancer that functions at post steps of siRNA production, efficiently reduced viral replication. The nucleotide sequence at the 5’ termini of SFV and SINV genome is conserved among the Old World alphaviruses, and mutating the conserved sequences resulted in the recombinant SFV being deficient in vsiRNA production and irresponsive to antiviral RNAi. SFV infection also enabled the production of abundant vsiRNAs and antiviral RNAi in IFN-competent adult mice, and importantly, enhanced RNAi by enoxacin protected adult mice from lethal SFV challenge and reduced the virus-induced neuropathogenesis in the central neuron system. Overall, our findings provide evidence that mammalian antiviral RNAi is active in differentiated cells and adult mice with intact IFN response even in the presence of VSR and present a therapeutic strategy against alphaviruses that include many important emerging and reemerging human pathogens.
2022-10-04 | GSE214453 | GEO
Project description:RNA interference (RNAi) is a cell-intrinsic antiviral defense conserved in diverse organisms. However, the mechanism by which mammalian antiviral RNAi is regulated is largely unknown. Herein, we uncover that STUB1, an E3 ubiquitin ligase, interacts with and ubiquitinates AGO2, the core component of RNAi pathway, resulting in the degradation of AGO2 via ubiquitin-proteasome system. Additionally, STUB1 can induce the degradation of the other mammalian AGO proteins including AGO1, AGO3, and AGO4. Our further study reveals that STUB1 also interacts with and mediates the ubiquitination of Dicer, the endoribonuclease responsible for siRNA or miRNA biogenesis, via K48-linked poly-ubiquitin, which induces the degradation of Dicer and its specialized form, termed antiviral Dicer (aviDicer) that usually expresses in stem cells. Loss of STUB1 upregulated Dicer and AGO2, thereby enhancing antiviral RNAi to effectively inhibit viral RNA replication in mammalian cells. In vivo, the STUB1 deficiency markedly enhanced the production of virus-derived siRNAs and elicited a potent antiviral effect against Enterovirus-A71 (EV-A71) infection in newborn mouse. Our findings demonstrate STUB1 as a novel negative regulator of RNAi by mediating the ubiquitination and degradation of Dicer and AGO proteins, and provide novel insights into the regulatory mechanism of antiviral RNAi in mammals.
2021-11-22 | GSE189203 | GEO
Project description:RNA interference (RNAi) functions as a potent antiviral immunity in plants and invertebrates, however whether RNAi plays antiviral roles in mammals remains unclear. Here, using human enterovirus 71 (HEV71) as a model, we showed HEV71 3A protein as an authentic viral suppressor of RNAi during viral infection. When the 3A-mediated RNAi suppression was impaired, the mutant HEV71 readily triggered the production of abundant HEV71-derived small RNAs with canonical siRNA properties in cells and mice. These virus-derived siRNAs were produced from viral dsRNA replicative intermediates in a Dicer-dependent manner, loaded into AGO, and were fully active in degrading cognate viral RNAs. Recombinant HEV71 deficient in 3A-mediated RNAi suppression was significantly restricted in human somatic cells and mice, whereas Dicer-deficiency rescued HEV71 infection independently of type I interferon response. Thus, RNAi can function as an antiviral immunity, which is induced and suppressed by a human virus, in mammals.
2017-08-01 | GSE99252 | GEO
Project description:Mosquito-borne flaviviruses maintain life cycles in mammals and mosquitoes. RNA interference (RNAi) has been demonstrated as an anti-flavivirus mechanism in mosquitoes; however, whether and how flavivirus induces and antagonizes RNAi-mediated antiviral immunity in mammals remains unknown. Here we showed that NS2A of Dengue virus-2 (DENV2) act as a viral suppressor of RNAi (VSR). When NS2A-mediated RNAi suppression was disabled, the resulting mutant DENV2 induced Dicer-dependent production of abundant DENV2-derived siRNAs in differentiated mammalian cells. Importantly, VSR-disabled DENV2 showed severe replication defects in mosquito and mammalian cells, and mice, which were rescued by the deficiency of RNAi. Moreover, NS2As of multiple flaviviruses act as VSRs in vitro and during viral infection in both organisms. Overall, our findings demonstrate that antiviral RNAi can be induced by flavivirus, while flavivirus uses NS2A as bona fide VSR to evade RNAi in mammals and mosquitoes, highlighting the importance of RNAi in flaviviral vector-host life cycles.
2020-02-24 | GSE133284 | GEO
Project description:While the intrinsic antiviral cell defenses of many kingdoms utilize pathogen-specific small RNAs, the antiviral response of chordates is primarily protein-based and not uniquely tailored to the incoming microbe. In an effort to explain this evolutionary bifurcation, we determined whether antiviral RNA interference (RNAi) was sufficient to replace the protein-based type I interferon (IFN-I) system of mammals. To this end, we recreated an RNAi-like response in mammals and determined its effectiveness to combat influenza A virus in vivo in the presence and absence of the canonical IFN-I system. Mammalian antiviral RNAi, elicited by either host- or virus-derived small RNAs, effectively attenuated virus and prevented disease independently of the innate immune response. These data find that chordates could have utilized RNAi as their primary antiviral cell defense and suggest that the IFN-I system emerged as a result of natural selection imposed by ancient pathogens.
2015-10-03 | GSE73698 | GEO
Project description:Antiviral RNAi response against the insect specific Agua Salud alphavirus
| PRJNA725665 | ENA
Project description:STUB1 regulates antiviral RNAi through inducing ubiquitination and degradation of Dicer and AGO2 in mammals
| PRJNA781958 | ENA
Project description:RNA interference (RNAi) is an antiviral immunity conserved in diverse eukaryotes including mammals, while viruses encodes viral suppressors of RNAi (VSRs) as countermeasures. However, the physiological impact of RNAi on viral infection in mammals has not been fully assessed, and it also remains unknown whether antiviral RNAi can be therapeutically exploited. Here, we show that peptides designed to target enterovirus A71 (EV-A71)-encoded protein 3A, a well-characterized VSR, triggered an effective antiviral response. These VSR-targeting peptides, particularly ER-DRI, abrogated the VSR function of 3A, which enabled EV-A71-derived siRNA production and unlocked RNAi response that potently inhibited EV-A71 infection in mammals. ER-DRI treatment elicited a strong in vivo antiviral RNAi response that protected mice against lethal EV-A71 challenge. It also potently inhibited another enterovirus, Coxsackievirus-A16, dependently of RNAi. Our findings demonstrate that antiviral RNAi does have a physiologically important impact in mammals and targeting VSRs is a promising strategy for antiviral therapies.
2021-07-31 | GSE179496 | GEO
Project description:RNA interference (RNAi) functions as the major host antiviral defense in insects, while less is understood about how to utilize antiviral RNAi in controlling viral infection in insects. Enoxacin belongs to the family of synthetic antibacterial compounds based on a fluoroquinolone skeleton that has been previously found to enhance RNAi in mammalian cells. In this study, we showed that enoxacin efficiently inhibited viral replication of Drosophila C virus (DCV) and Cricket paralysis virus (CrPV) in cultured Drosophila cells. Enoxacin promoted the loading of Dicer-2-processed virus-derived siRNA into the RNA-induced silencing complex, thereby enhancing antiviral RNAi response in infected cells. Moreover, enoxacin treatment elicited an RNAi-dependent in vivo protective efficacy against DCV or CrPV challenge in adult fruit flies. In addition, enoxacin also inhibited replication of flaviviruses, including Dengue virus and Zika virus, in Aedes mosquito cells in an RNAi-dependent manner. Together, our findings demonstrated that enoxacin can enhance RNAi in insects, and enhancing RNAi by enoxacin is an effective antiviral strategy against diverse viruses in insects, which may be exploited as a broad-spectrum antiviral agent to control vector transmission of arboviruses or viral diseases in insect farming.
2021-11-22 | GSE189204 | GEO
Project description:Plants and invertebrates protect themselves from viruses through RNA interference (RNAi), yet it remains unknown whether this defense mechanism exists in mammals. Antiviral RNAi involves the processing of viral long double-stranded (ds) RNA molecules into small interfering RNAs (siRNAs) by the ribonuclease (RNAse) III Dicer. These siRNAs are incorporated into effector complex(es) containing members of the Argonaute (Ago) protein family and guide silencing of complementary target viral RNAs. Here, we detect the accumulation of phased Dicer-dependent virus-derived siRNA (viRNAs) and demonstrate their loading into Ago2 after infection of mouse embryonic stem (ES) cells with Encephalomyocarditis virus (EMCV). We further show that the production of these viRNAs is drastically reduced, yet not completely abolished, if ES cells are first induced to differentiate before infection. Finally, we reveal that the mammalian virus Nodamura virus (NoV) encodes for a protein that counteracts such antiviral RNAi in ES cells supporting the existence of an effective RNAi-based immunity in mammals. Infection of wild-type or mutant mouse ES cells and analysis of small RNAs from total extracts or immunoprecipitated components of the RNAi pathway
2013-10-10 | E-GEOD-43153 | biostudies-arrayexpress