Alphavirus infection triggers antiviral RNAi immunity in mammals
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ABSTRACT:
PROVIDER: PRJNA786627 | 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) 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: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:Screening of the interacting molecular of AGO2 in mammals
2022-03-28 | PXD032854 | iProX
Project description:Most alphaviruses are transmitted by mosquito vectors and infect a wide range of vertebrate hosts, with a few exceptions. Eilat virus (EILV) in this genus is characterized by a host range restricted to mosquitoes. Its chimeric viruses have been developed as safe and effective vaccine candidates and diagnostic tools. Here, we investigated the interactions between these insect-specific viruses (ISVs) and mosquito cells, unveiling their potential roles in determining vector competence and arbovirus transmission. By RNA sequencing, we found that these ISVs profoundly modified host cell gene expression profiles. Two EILV-based chimeras, consisting of EILV’s nonstructural genes and the structural genes of Chikungunya virus (CHIKV) or Venezuelan equine encephalitis virus (VEEV), namely EILV/CHIKV (E/C) and EILV/VEEV (E/V), induced more intensive transcriptome regulation than parental EILV and activated different antiviral mechanisms in host cells. We demonstrated that E/C robustly promoted antimicrobial peptide production and E/V strongly upregulated the RNA interference pathway components. This also highlighted the intrinsic divergences between CHIKV and VEEV, representatives of the Old World and New World alphaviruses. In contrast, EILV triggered a limited antiviral response. We further showed that initial chimera infections efficiently inhibited subsequent pathogenic alphavirus replication, especially in the case of E/V infection, which almost prevented VEEV and Sindbis virus (SINV) superinfections. Altogether our study provided valuable information on developing ISVs as biological control agents.
2023-01-19 | GSE220562 | 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:Antiviral RNAi response against the insect specific Agua Salud alphavirus
| PRJNA725665 | ENA
Project description:The re-emergence of Zika virus (ZIKV) in the Western Hemisphere has resulted in global public health crisis since 2015. ZIKV preferentially infects and targets human neural progenitor cells (hNPCs) and causes fetal microcephaly upon maternal infection. hNPCs not only play critical roles during fetal brain development, but also persist in adult brain throughout life. Yet the mechanism of innate antiviral immunity in hNPCs remains largely unknown. Here, we show that ZIKV infection triggers the abundant production of virus-derived small interfering RNAs in hNPCs, but not in the more differentiated progenies or somatic cells. Ablation of key RNAi machinery components significantly enhances ZIKV replication in hNPCs. Furthermore, enoxacin, a broad-spectrum antibiotic that is known as an RNAi enhancer, exerts potent anti-ZIKV activity in hNPCs and other RNAi-competent cells. Strikingly, enoxacin treatment completely prevents ZIKV infection and circumvents ZIKV-induced microcephalic phenotypes in brain organoid models that recapitulate human fetal brain development. Our findings highlight the physiological importance of RNAi-mediated antiviral immunity during the early stage of human brain development, uncovering a novel strategy to combat human congenital viral infections through enhancing RNAi.
2019-04-15 | GSE125520 | GEO
Project description:Mitochondria are descendants of endosymbiotic bacteria and retain essential prokaryotic features such as a compact circular genome. Consequently, in mammals, mitochondrial DNA is subjected to bidirectional transcription that generates overlapping transcripts capable of forming long double-stranded RNA structures. However, to our knowledge, mitochondrial double-stranded RNA has not been previously characterized in vivo. Here, we describe the presence of a highly unstable native mitochondrial double-stranded RNA species at single cell level and identify keyroles for the degradosome components, mitochondrial dsRNA helicase SUV3 and polynucleotide phosphorylase PNPase in restricting the levels of mitochondrial double-stranded RNA. Loss of either enzyme results in massive accumulation of mitochondrial double-stranded RNA that escapes into the cytoplasm in a PNPase-dependent manner. This process engages an MDA5-driven antiviral signalling pathway that triggers a type I interferon response. Consistent with these data, patients carrying hypomorphic mutations in the gene PNPT1, which encodes PNPase, display mitochondrial double-stranded RNA accumulation coupled with upregulation of interferon-stimulated genes and other markers of immune activation. The localization of PNPase to the mitochondrial inter-membrane space and matrix suggests that it has a dual role in preventing the formation and release of mitochondrial double-stranded RNA into the cytoplasm. This in turn prevents the activation of potent innate immune defence mechanisms evolved to protect vertebrates against microbial and viral attack.
2018-05-03 | GSE94957 | 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