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Project description:DUSP11-mediated Control of 5’-Triphosphate RNA Regulates RIG-I Sensitivity
| PRJNA666674 | ENA
Project description:Deciphering the mechanisms that regulate the sensitivity of pathogen recognition receptors is imperative to understanding infection and inflammation. Here we demonstrate that the RNA triphosphatase dual-specificity phosphatase 11 (DUSP11) acts on both host and virus-derived 5'-triphosphate RNAs rendering them less active in inducing a RIG-I-mediated immune response. Reducing DUSP11 levels alters host triphosphate RNA packaged in extracellular vesicles and induces enhanced RIG-I activation in cells exposed to extracellular vesicles. Virus infection of cells lacking DUSP11 results in a higher proportion of triphosphorylated viral transcripts and attenuated virus replication, which is rescued by reducing RIG-I expression. Consistent with the activity of DUSP11 in the cellular RIG-I response, mice lacking DUSP11 display lower viral loads, greater sensitivity to triphosphorylated RNA, and a signature of enhanced interferon activity in select tissues. Our results reveal the importance of controlling 5'-triphosphate RNA levels to prevent aberrant RIG-I signaling and demonstrate DUSP11 as a key effector of this mechanism.
| S-EPMC7706711 | biostudies-literature
Project description:Retinoic acid-inducible gene I (RIG-I) is up-regulated during granulocytic differentiation of acute promyelocytic leukemia (APL) cells induced by all-trans retinoic acid (ATRA). It has been reported that RIG-I recognizes virus-specific 5'-ppp-double-stranded RNA (dsRNA) and activates the type I interferons signaling pathways in innate immunity. However, the functions of RIG-I in hematopoiesis remain unclear, especially regarding its possible interaction with endogenous RNAs and the associated pathways that could contribute to the cellular differentiation and maturation. Herein, we identified a number of RIG-I-binding endogenous RNAs in APL cells following ATRA treatment, including the tripartite motif-containing protein 25 (TRIM25) messenger RNA (mRNA). TRIM25 encodes the protein known as an E3 ligase for ubiquitin/interferon (IFN)-induced 15-kDa protein (ISG15) that is involved in RIG-I-mediated antiviral signaling. We show that RIG-I could bind TRIM25 mRNA via its helicase domain and C-terminal regulatory domain, enhancing the stability of TRIM25 transcripts. RIG-I could increase the transcriptional expression of TRIM25 by caspase recruitment domain (CARD) domain through an IFN-stimulated response element. In addition, RIG-I activated other key genes in the ISGylation pathway by activating signal transducer and activator of transcription 1 (STAT1), including the modifier ISG15 and several enzymes responsible for the conjugation of ISG15 to protein substrates. RIG-I cooperated with STAT1/2 and interferon regulatory factor 1 (IRF1) to promote the activation of the ISGylation pathway. The integrity of ISGylation in ATRA or RIG-I-induced cell differentiation was essential given that knockdown of TRIM25 or ISG15 resulted in significant inhibition of this process. Our results provide insight into the role of the RIG-I-TRIM25-ISGylation axis in myeloid differentiation.
| S-EPMC7322067 | biostudies-literature
Project description:BackgroundDouble stranded RNA (dsRNA) is widely accepted as an RNA motif recognized as a danger signal by the cellular sentries. However, the biology of non-segmented negative strand RNA viruses, or Mononegavirales, is hardly compatible with the production of such dsRNA.Methodology and principal findingsDuring measles virus infection, the IFN-beta gene transcription was found to be paralleled by the virus transcription, but not by the virus replication. Since the expression of every individual viral mRNA failed to activate the IFN-beta gene, we postulated the involvement of the leader RNA, which is a small not capped and not polyadenylated RNA firstly transcribed by Mononegavirales. The measles virus leader RNA, synthesized both in vitro and in vivo, was efficient in inducing the IFN-beta expression, provided that it was delivered into the cytosol as a 5'-trisphosphate ended RNA. The use of a human cell line expressing a debilitated RIG-I molecule, together with overexpression studies of wild type RIG-I, showed that the IFN-beta induction by virus infection or by leader RNA required RIG-I to be functional. RIG-I binds to leader RNA independently from being 5-trisphosphate ended; while a point mutant, Q299A, predicted to establish contacts with the RNA, fails to bind to leader RNA. Since the 5'-triphosphate is required for optimal RIG-I activation but not for leader RNA binding, our data support that RIG-I is activated upon recognition of the 5'-triphosphate RNA end.Conclusions/significanceRIG-I is proposed to recognize Mononegavirales transcription, which occurs in the cytosol, while scanning cytosolic RNAs, and to trigger an IFN response when encountering a free 5'-triphosphate RNA resulting from a mislocated transcription activity, which is therefore considered as the hallmark of a foreign invader.
| S-EPMC1804102 | biostudies-literature
Project description:The RIG-I-like receptors (RLRs: RIG-I, MDA5 and LGP2) trigger inflammatory and antiviral responses by sensing non-self RNA molecules produced during viral replication. LGP2 regulation of RIG-I and MDA5-dependant type-I interferon signaling is a matter of controversy. Here we show that LGP2 interacts with different components of the RNA silencing machinery. Particularly, we identified a direct protein-protein interaction between LGP2 and interferon-inducible double-stranded RNA-dependent protein kinase activator A (PACT). The LGP2-PACT interaction is mediated by the regulatory C-terminal domain of LGP2 and is necessary for inhibiting the RIG-I- and amplifying the MDA5-responses. We describe a point mutation within LGP2 that disrupts LGP2-PACT interaction and leads to the loss of LGP2 regulatory activity over RIG-I and MDA5. These results provide a model in which PACT-LGP2 interaction regulates RIG-I and MDA5 inflammatory response and allows cellular RNA silencing machinery to coordinate the innate immune response.
2019-10-02 | PXD013191 | Pride
Project description:The retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), including RIG-I and melanoma differentiation-associated gene 5 (MDA5), sense cytoplasmic viral RNA and initiate innate antiviral responses. How RIG-I and MDA5 are differentially regulated remains enigmatic. In this study, we identified the guanylate-binding protein (GBP) and zinc-finger FYVE domain-containing protein ZFYVE1 as a negative regulator of MDA5- but not RIG-I-mediated innate antiviral responses. ZFYVE1-deficiency promoted MDA5- but not RIG-I-mediated transcription of downstream antiviral genes. Comparing to wild-type mice, Zfyve1-/- mice were significantly protected from lethality induced by encephalomyocarditis virus (EMCV) that is sensed by MDA5, whereas Zfyve1-/- and Zfyve1+/+ mice were comparable to death induced by vesicular stomatitis virus (VSV) that is sensed by RIG-I. Mechanistically, ZFYVE1 interacted with MDA5 but not RIG-I. ZFYVE1 bound to viral RNA and decreased the ligand binding and oligomerization of MDA5. These findings suggest that ZFYVE1 acts as a specific negative regulator of MDA5-mediated innate immune responses by inhibiting its ligand binding and oligomerization.
| S-EPMC7162542 | biostudies-literature
Project description:The ATPase retinoid acid-inducible gene (RIG)-I senses viral RNA in the cytoplasm of infected cells and subsequently activates cellular antiviral defense mechanisms. RIG-I recognizes molecular structures that discriminate viral from host RNA. Here, we show that RIG-I ligands require base-paired structures in conjunction with a free 5'-triphosphate to trigger antiviral signaling. Hitherto unavailable chemically synthesized 5'-triphosphate RNA ligands do not trigger RIG-I-dependent IFN production in cells, and they are unable to trigger the ATPase activity of RIG-I without a base-paired stretch. Consistently, immunostimulatory RNA from cells infected with a virus recognized by RIG-I is sensitive to double-strand, but not single-strand, specific RNases. In vitro, base-paired stretches and the 5'-triphosphate bind to distinct sites of RIG-I and synergize to trigger the induction of signaling competent RIG-I multimers. Strengthening our model of a bipartite molecular pattern for RIG-I activation, we show that the activity of supposedly "single-stranded" 5'-triphosphate RNAs generated by in vitro transcription depends on extended and base-paired by-products inadvertently, but commonly, produced by this method. Together, our findings accurately define a minimal molecular pattern sufficient to activate RIG-I that can be found in viral genomes or transcripts.
| S-EPMC2705279 | biostudies-literature
Project description:Retinoic acid inducible-gene I (RIG-I) is a cytosolic multidomain protein that detects viral RNA and elicits an antiviral immune response. Two N-terminal caspase activation and recruitment domains (CARDs) transmit the signal, and the regulatory domain prevents signaling in the absence of viral RNA. 5'-triphosphate and double-stranded RNA (dsRNA) are two molecular patterns that enable RIG-I to discriminate pathogenic from self-RNA. However, the function of the DExH box helicase domain that is also required for activity is less clear. Using single-molecule protein-induced fluorescence enhancement, we discovered a robust adenosine 5'-triphosphate-powered dsRNA translocation activity of RIG-I. The CARDs dramatically suppress translocation in the absence of 5'-triphosphate, and the activation by 5'-triphosphate triggers RIG-I to translocate preferentially on dsRNA in cis. This functional integration of two RNA molecular patterns may provide a means to specifically sense and counteract replicating viruses.
| S-EPMC3567915 | biostudies-literature
Project description:RIG-I is a cytosolic receptor for non-self RNA that mediates immune responses against viral infections through IFN?/? production. In an attempt to identify novel tools that modulate IFN?/? production, we used SELEX technology to screen RNA aptamers that specifically target RIG-I protein. Most of the selected RIG-I aptamers contained polyU motifs in the second half regions that played critical roles in the activation of RIG-I-mediated IFN? production. Unlike other known ligands, RIG-I aptamer bound and activated RIG-I in a 5'-triphosphate-independent manner. The helicase and RD domain of RIG-I were used for aptamer binding, but intact RIG-I protein was required to exert aptamer-mediated signaling activation. Furthermore, replication of NDV, VSV and influenza virus in infected host cells was efficiently blocked by pre- or post-treatment with RIG-I aptamer. Based on these data, we propose that RIG-I aptamer has strong potential to be an antiviral agent that specifically boosts the RIG-I-dependent signaling cascade.
| S-EPMC3315321 | biostudies-literature
Project description:Upon viral infections, pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs) and stimulate an antiviral state associated with the production of type I interferons (IFNs) and inflammatory markers. Type I IFNs play crucial roles in innate antiviral responses by inducing expression of interferon-stimulated genes and by activating components of the adaptive immune system. Although pegylated IFNs have been used to treat hepatitis B and C virus infections for decades, they exert substantial side effects that limit their use. Current efforts are directed toward the use of PRR agonists as an alternative approach to elicit host antiviral responses in a manner similar to that achieved in a natural infection. RIG-I is a cytosolic PRR that recognizes 5' triphosphate (5'ppp)-containing RNA ligands. Due to its ubiquitous expression profile, induction of the RIG-I pathway provides a promising platform for the development of novel antiviral agents and vaccine adjuvants. In this study, we investigated whether structured RNA elements in the genome of coxsackievirus B3 (CVB3), a picornavirus that is recognized by MDA5 during infection, could activate RIG-I when supplied with 5'ppp. We show here that a 5'ppp-containing cloverleaf (CL) RNA structure is a potent RIG-I inducer that elicits an extensive antiviral response that includes induction of classical interferon-stimulated genes, as well as type III IFNs and proinflammatory cytokines and chemokines. In addition, we show that prophylactic treatment with CVB3 CL provides protection against various viral infections including dengue virus, vesicular stomatitis virus and enterovirus 71, demonstrating the antiviral efficacy of this RNA ligand.
| S-EPMC3997492 | biostudies-literature