OAS1/RNase L executes RIG-I ligand–dependent tumor cell apoptosis

2021 ◽  
Vol 6 (61) ◽  
pp. eabe2550
Author(s):  
Daniel F. R. Boehmer ◽  
Simone Formisano ◽  
Carina C. de Oliveira Mann ◽  
Stephan A. Mueller ◽  
Michael Kluge ◽  
...  
Keyword(s):  
Affinity Purification ◽  
Type I Interferons ◽  
Type I ◽  
Rnase L ◽  
Oligoadenylate Synthetase ◽  
Bona Fide ◽  
Translational Arrest ◽  
Effector Pathways ◽  
Induced Apoptosis ◽  
Mediated Priming

Cytoplasmic double-stranded RNA is sensed by RIG-I–like receptors (RLRs), leading to induction of type I interferons (IFN-Is), proinflammatory cytokines, and apoptosis. Here, we elucidate signaling mechanisms that lead to cytokine secretion and cell death induction upon stimulation with the bona fide RIG-I ligand 5′-triphosphate RNA (3p-RNA) in tumor cells. We show that both outcomes are mediated by dsRNA-receptor families with RLR being essential for cytokine production and IFN-I–mediated priming of effector pathways but not for apoptosis. Affinity purification followed by mass spectrometry and subsequent functional analysis revealed that 3p-RNA bound and activated oligoadenylate synthetase 1 and RNase L. RNase L–deficient cells were profoundly impaired in their ability to undergo apoptosis. Mechanistically, the concerted action of translational arrest triggered by RNase L and up-regulation of NOXA was needed to deplete the antiapoptotic MCL-1 to cause intrinsic apoptosis. Thus, 3p-RNA–induced apoptosis is a two-step process consisting of RIG-I–dependent priming and an RNase L–dependent effector phase.

scholarly journals Heterozygous OAS1 gain-of-function variants cause an autoinflammatory immunodeficiency

2021 ◽  
Vol 6 (60) ◽  
pp. eabf9564
Author(s):  
Thomas Magg ◽  
Tsubasa Okano ◽  
Lars M. Koenig ◽  
Daniel F.R. Boehmer ◽  
Samantha L. Schwartz ◽  
...  
Keyword(s):  
B Cells ◽  
Hematopoietic Cell Transplantation ◽  
De Novo ◽  
Dynamics Simulation ◽  
Recurrent Fever ◽  
Type I ◽  
Rnase L ◽  
Oligoadenylate Synthetase ◽  
Gain Of Function ◽  
Translational Arrest

Analysis of autoinflammatory and immunodeficiency disorders elucidates human immunity and fosters the development of targeted therapies. Oligoadenylate synthetase 1 is a type I interferon–induced, intracellular double-stranded RNA (dsRNA) sensor that generates 2′-5′-oligoadenylate to activate ribonuclease L (RNase L) as a means of antiviral defense. We identified four de novo heterozygous OAS1 gain-of-function variants in six patients with a polymorphic autoinflammatory immunodeficiency characterized by recurrent fever, dermatitis, inflammatory bowel disease, pulmonary alveolar proteinosis, and hypogammaglobulinemia. To establish causality, we applied genetic, molecular dynamics simulation, biochemical, and cellular functional analyses in heterologous, autologous, and inducible pluripotent stem cell–derived macrophages and/or monocytes and B cells. We found that upon interferon-induced expression, OAS1 variant proteins displayed dsRNA-independent activity, which resulted in RNase L–mediated RNA cleavage, transcriptomic alteration, translational arrest, and dysfunction and apoptosis of monocytes, macrophages, and B cells. RNase L inhibition with curcumin modulated and allogeneic hematopoietic cell transplantation cured the disorder. Together, these data suggest that human OAS1 is a regulator of interferon-induced hyperinflammatory monocyte, macrophage, and B cell pathophysiology.

scholarly journals Cytosolic DNA sensor-initiated innate immune responses in mouse ovarian granulosa cells

Reproduction ◽  
2017 ◽  
Vol 153 (6) ◽  
pp. 821-834 ◽  
Author(s):  
Keqin Yan ◽  
Dingqing Feng ◽  
Jing Liang ◽  
Qing Wang ◽  
Lin Deng ◽  
...  
Keyword(s):  
Immune Responses ◽  
Granulosa Cells ◽  
Innate Immune ◽  
Type I Interferons ◽  
Endocrine Function ◽  
Type I ◽  
Dna Sensor ◽  
Innate Immune Responses ◽  
Oligoadenylate Synthetase ◽  
Ovarian Granulosa Cells

Viral infections of the ovary may perturb ovarian functions. However, the mechanisms underlying innate immune responses in the ovary are poorly understood. The present study demonstrates that cytosolic viral DNA sensor signaling initiates the innate immune response in mouse ovarian granulosa cells and affects endocrine function. The cytosolic DNA sensors p204 and cGAS and their common signaling adaptor stimulator of interferon (IFN) genes (STING) were constitutively expressed in granulosa cells. Transfection with VACV70, a synthetic vaccinia virus (VACV) DNA analog, induced the expression of type I interferons (IFNA/B) and major inflammatory cytokines (TNFA and IL6) through IRF3 and NF-κB activation respectively. Moreover, several IFN-inducible antiviral proteins, including 2′,5′-oligoadenylate synthetase, IFN-stimulating gene 15 and Mx GTPase 1, were also induced by VACV70 transfection. The innate immune responses in granulosa cells were significantly reduced by the transfection of specific small-interfering RNAs targeting p204, cGas or Sting. Notably, the VACV70-triggered innate immune responses affected steroidogenesis in vivo and in vitro. The data presented in this study describe the mechanism underlying ovarian immune responses to viral infection.

scholarly journals Anti-Human Immunodeficiency Virus Activity of Tau Interferon in Human Macrophages: Involvement of Cellular Factors and β-Chemokines

2003 ◽  
Vol 77 (23) ◽  
pp. 12914-12920 ◽  
Author(s):  
Christine Rogez ◽  
Marc Martin ◽  
Nathalie Dereuddre-Bosquet ◽  
Jacques Martal ◽  
Dominique Dormont ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Monocyte ◽  
Type I ◽  
Rnase L ◽  
Oligoadenylate Synthetase ◽  
Hiv Replication ◽  
Human Macrophages ◽  
Hiv Rna ◽  
Type I Ifns ◽  
Immunodeficiency Virus

ABSTRACT Tau interferon (IFN-τ) is a noncytotoxic type I IFN responsible for maternal recognition of the fetus in ruminants. IFN-τ inhibits human immunodeficiency virus (HIV) replication more strongly than human IFN-α, particularly in human monocyte-derived macrophages. In this study performed in human macrophages, IFN-τ efficiently inhibited the early steps of the biological cycle of HIV, decreasing intracellular HIV RNA and inhibiting the initiation of the reverse transcription of viral RNA into proviral DNA. Two mechanisms induced by IFN-τ treatment in macrophages may account for this inhibition: (i) the synthesis of the cellular antiviral factors such as 2′,5′-oligoadenylate synthetase/RNase L and MxA protein and (ii) an increased production of MIP-1α, MIP-1β, and RANTES, which are natural ligands of CCR5, the principal coreceptor of HIV on macrophages. Our results suggest that IFN-τ induces the same antiviral pathways in macrophages as other type I IFNs but without associated toxicity.

scholarly journals Zika Virus Production Is Resistant to RNase L Antiviral Activity

2019 ◽  
Vol 93 (16) ◽  
Author(s):  
Jillian N. Whelan ◽  
Yize Li ◽  
Robert H. Silverman ◽  
Susan R. Weiss
Keyword(s):  
Antiviral Activity ◽  
Zika Virus ◽  
Viral Genome ◽  
Molecular Mechanisms ◽  
Virus Production ◽  
Type I ◽  
Rnase L ◽  
Oligoadenylate Synthetase ◽  
Zikv Infection ◽  
Initial Report

SUMMARYThere is currently no knowledge of how the emerging human pathogen Zika virus (ZIKV) interacts with the antiviral endoribonuclease L (RNase L) pathway during infection. Since activation of RNase L during infection typically limits virus production dramatically, we used CRISPR-Cas9 gene editing technology to knockout (KO) targeted host genes involved in the RNase L pathway to evaluate the effects of RNase L on ZIKV infection in human A549 cells. RNase L was activated in response to ZIKV infection, which degraded ZIKV genomic RNA. Surprisingly, despite viral genome reduction, RNase L activity did not reduce ZIKV infectious titers. In contrast, both the flavivirus dengue virus and the alphavirus Sindbis virus replicated to significantly higher titers in RNase L KO cells compared to wild-type (WT) cells. Using MAVS/RNase L double KO cells, we demonstrated that the absence of increased ZIKV production in RNase L KO cells was not due to compensation by enhanced type I interferon transcripts to thus inhibit virus production. Finally, when synthetic double-stranded RNA was detected by OAS3 to induce RNase L antiviral activity prior to ZIKV infection, we observed reduced ZIKV replication factory formation, as well as a 42-fold reduction in virus yield in WT but not RNase L KO cells. This study proposes that ZIKV evades RNase L antiviral activity by generating a viral genome reservoir protected from RNase L cleavage during early infection, allowing for sufficient virus production before RNase L activation is detectable.IMPORTANCEWith the onset of the 2015 ZIKV outbreak, ZIKV pathogenesis has been of extreme global public health interest, and a better understanding of interactions with the host would provide insight into molecular mechanisms driving the severe neurological outcomes of ZIKV disease. Here is the initial report on the relationship between ZIKV and the host oligoadenylate synthetase-RNase L (OAS-RNase L) system, a potent antiviral pathway effective at restricting replication of diverse viruses. Our study elucidated a unique mechanism whereby ZIKV production is impervious to antiviral RNase L activity, through a mechanism of viral RNA protection that is not mimicked during infection with numerous other RNase L-activating viruses, thus identifying a distinct replication strategy potentially important for ZIKV pathogenesis.

scholarly journals Cell-Type-Specific Effects of RNase L on Viral Induction of Beta Interferon

mBio ◽  
2014 ◽  
Vol 5 (2) ◽  
Author(s):  
Shuvojit Banerjee ◽  
Arindam Chakrabarti ◽  
Babal Kant Jha ◽  
Susan R. Weiss ◽  
Robert H. Silverman
Keyword(s):  
Viral Infections ◽  
Type I Interferons ◽  
Type I ◽  
Rnase L ◽  
Cell Type ◽  
Mouse Embryonic Fibroblasts ◽  
Embryonic Fibroblasts ◽  
Tissue Protection ◽  
Rna Damage ◽  
Cell Type Specific

ABSTRACTThe interferon (IFN)-inducible antiviral state is mediated in part by the 2′,5′-oligoadenylate (2-5A) synthetase (OAS)/RNase L system. 2-5A, produced from ATP by OAS proteins in response to viral double-stranded RNA, binds to and activates RNase L. RNase L restricts viral infections by degrading viral and cellular RNA, inducing autophagy and apoptosis, and producing RNA degradation products that amplify production of type I interferons (IFNs) through RIG-I-like receptors. However, the effects of the OAS/RNase L pathway on IFN induction in different cell types that vary in basal levels of these proteins have not been previously reported. Here we report higher basal expression of both RNase L and OAS in mouse macrophages in comparison to mouse embryonic fibroblasts (MEFs). In MEFs, RNase L gene knockout decreased induction of IFN-β by encephalomyocarditis virus infection or poly(rI):poly(rC) (pIC) transfection. In contrast, in macrophages, RNase L deletion increased (rather than decreased) induction of IFN-β by virus or pIC. RNA damage from RNase L in virus-infected macrophages is likely responsible for reducing IFN-β production. Similarly, direct activation of RNase L by transfection with 2-5A induced IFN-β in MEFs but not in macrophages. Also, viral infection or pIC transfection caused RNase L-dependent apoptosis of macrophages but not of MEFs. Our results suggest that cell-type-specific differences in basal levels of OAS and RNase L are determinants of IFN-β induction that could affect tissue protection and survival during viral infections.IMPORTANCEType I interferons (IFNs) such as IFN-β are essential antiviral cytokines that are often required for animal survival following infections by highly pathogenic viruses. Therefore, host factors that regulate type I IFN production are critically important for animal and human health. Previously we reported that the OAS/RNase L pathway amplifies antiviral innate immunity by enhancing IFN-β production in mouse embryonic fibroblasts and in virus-infected mice. Here we report that high basal levels of OAS/RNase L in macrophages reduce, rather than increase, virus induction of IFN-β. RNA damage and apoptosis caused by RNase L were the likely reasons for the decreased IFN-β production in virus-infected macrophages. Our studies suggest that during viral infections, the OAS/RNase L pathway can either enhance or suppress IFN production, depending on the cell type. IFN regulation by RNase L is suggested to contribute to tissue protection and survival during viral infections.

scholarly journals ABCE1 Regulates RNase L-Induced Autophagy during Viral Infections

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 315
Author(s):  
Barkha Ramnani ◽  
Praveen Manivannan ◽  
Sarah Jaggernauth ◽  
Krishnamurthy Malathi
Keyword(s):  
Cellular Proliferation ◽  
Viral Infections ◽  
Antiviral Effect ◽  
Host Protein ◽  
Type I ◽  
Rnase L ◽  
Oligoadenylate Synthetase ◽  
Interferon Stimulated Genes ◽  
Antiviral Effects ◽  
Increased Activity

Host response to a viral infection includes the production of type I interferon (IFN) and the induction of interferon-stimulated genes that have broad antiviral effects. One of the key antiviral effectors is the IFN-inducible oligoadenylate synthetase/ribonuclease L (OAS/RNase L) pathway, which is activated by double-stranded RNA to synthesize unique oligoadenylates, 2-5A, to activate RNase L. RNase L exerts an antiviral effect by cleaving diverse RNA substrates, limiting viral replication; many viruses have evolved mechanisms to counteract the OAS/RNase L pathway. Here, we show that the ATP-binding cassette E1 (ABCE1) transporter, identified as an inhibitor of RNase L, regulates RNase L activity and RNase L-induced autophagy during viral infections. ABCE1 knockdown cells show increased RNase L activity when activated by 2-5A. Compared to parental cells, the autophagy-inducing activity of RNase L in ABCE1-depleted cells is enhanced with early onset. RNase L activation in ABCE1-depleted cells inhibits cellular proliferation and sensitizes cells to apoptosis. Increased activity of caspase-3 causes premature cleavage of autophagy protein, Beclin-1, promoting a switch from autophagy to apoptosis. ABCE1 regulates autophagy during EMCV infection, and enhanced autophagy in ABCE1 knockdown cells promotes EMCV replication. We identify ABCE1 as a host protein that inhibits the OAS/RNase L pathway by regulating RNase L activity, potentially affecting antiviral effects.

scholarly journals RNase L Antiviral Activity Is Not a Critical Component of the Oas1b-Mediated Flavivirus Resistance Phenotype

2019 ◽  
Vol 93 (22) ◽  
Author(s):  
J. C. Madden ◽  
Dan Cui ◽  
M. A. Brinton
Keyword(s):  
Antiviral Activity ◽  
Full Length ◽  
Viral Rna ◽  
Type I ◽  
Mrna Levels ◽  
Rnase L ◽  
Oligoadenylate Synthetase ◽  
Resistant Mouse ◽  
Resistance Phenotype

ABSTRACT In mice, resistance to central nervous system (CNS) disease induced by members of the genus Flavivirus is conferred by an allele of the 2′-5′ oligoadenylate synthetase 1b gene that encodes the inactive full-length protein (Oas1b-FL). The susceptibility allele encodes a C-terminally truncated protein (Oas1b-tr). We show that the efficiency of neuron infection in the brains of resistant and susceptible mice is similar after an intracranial inoculation of two flaviviruses, but amplification of viral proteins and double-stranded RNA (dsRNA) is inhibited in infected neurons in resistant mouse brains at later times. Active OAS proteins detect cytoplasmic dsRNA and synthesize short 2′-5′-linked oligoadenylates (2′-5′A) that interact with the latent endonuclease RNase L, causing it to dimerize and cleave single-stranded RNAs. To evaluate the contribution of RNase L to the resistance phenotype in vivo, we created a line of resistant RNase L−/− mice. Evidence of RNase L activation in infected RNase L+/+ mice was indicated by higher levels of viral RNA in the brains of infected RNase L−/− mice. Activation of type I interferon (IFN) signaling was detected in both resistant and susceptible brains, but Oas1a and Oas1b mRNA levels were lower in RNase L+/+ mice of both types, suggesting that activated RNase L also has a proflaviviral effect. Inhibition of virus replication was robust in resistant RNase L−/− mice, indicating that activated RNase L is not a critical factor in mediating this phenotype. IMPORTANCE The mouse genome encodes a family of Oas proteins that synthesize 2′-5′A in response to dsRNA. 2′-5′A activates the endonuclease RNase L to cleave single-stranded viral and cellular RNAs. The inactive, full-length Oas1b protein confers flavivirus-specific disease resistance. Although similar numbers of neurons were infected in resistant and susceptible brains after an intracranial virus infection, viral components amplified only in susceptible brains at later times. A line of resistant RNase L−/− mice was used to evaluate the contribution of RNase L to the resistance phenotype in vivo. Activation of RNase L antiviral activity by flavivirus infection was indicated by increased viral RNA levels in the brains of RNase L−/− mice. Oas1a and Oas1b mRNA levels were higher in infected RNase L−/− mice, indicating that activated RNase L also have a proflaviviral affect. However, the resistance phenotype was equally robust in RNase L−/− and RNase L+/+ mice.

scholarly journals Activation of RNase L by Murine Coronavirus in Myeloid Cells Is Dependent on BasalOasGene Expression and Independent of Virus-Induced Interferon

2016 ◽  
Vol 90 (6) ◽  
pp. 3160-3172 ◽  
Author(s):  
L. Dillon Birdwell ◽  
Zachary B. Zalinger ◽  
Yize Li ◽  
Patrick W. Wright ◽  
Ruth Elliott ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antiviral Activity ◽  
Hepatitis Virus ◽  
Mouse Hepatitis Virus ◽  
Myeloid Cells ◽  
Type I ◽  
Rnase L ◽  
Oligoadenylate Synthetase ◽  
Double Stranded Rna ◽  
Murine Coronavirus

ABSTRACTThe oligoadenylate synthetase (OAS)-RNase L pathway is a potent interferon (IFN)-induced antiviral activity. Upon sensing double-stranded RNA, OAS produces 2′,5′-oligoadenylates (2-5A), which activate RNase L. Murine coronavirus (mouse hepatitis virus [MHV]) nonstructural protein 2 (ns2) is a 2′,5′-phosphodiesterase (PDE) that cleaves 2-5A, thereby antagonizing RNase L activation. PDE activity is required for robust replication in myeloid cells, as a mutant of MHV (ns2H126R) encoding an inactive PDE fails to antagonize RNase L activation and replicates poorly in bone marrow-derived macrophages (BMM), while ns2H126Rreplicates to high titer in several types of nonmyeloid cells, as well as in IFN receptor-deficient (Ifnar1−/−) BMM. We reported previously that myeloid cells express significantly higher basal levels of OAS transcripts than nonmyeloid cells. Here, we investigated the contributions ofOasgene expression, basal IFN signaling, and virus-induced IFN to RNase L activation. Infection with ns2H126Ractivated RNase L inIfih1−/−BMM to a similar extent as in wild-type (WT) BMM, despite the lack of IFN induction in the absence of MDA5 expression. However, ns2H126Rfailed to induce RNase L activation in BMM treated with IFNAR1-blocking antibody, as well as inIfnar1−/−BMM, both expressing low basal levels ofOasgenes. Thus, activation of RNase L does not require virus-induced IFN but rather correlates with adequate levels of basalOasgene expression, maintained by basal IFN signaling. Finally, overexpression of RNase L is not sufficient to compensate for inadequate basal OAS levels.IMPORTANCEThe oligoadenylate synthetase (OAS)-RNase L pathway is a potent antiviral activity. Activation of RNase L during murine coronavirus (mouse hepatitis virus [MHV]) infection of myeloid cells correlates with high basalOasgene expression and is independent of virus-induced interferon secretion. Thus, our data suggest that cells with high basalOasgene expression levels can activate RNase L and thereby inhibit virus replication early in infection upon exposure to viral double-stranded RNA (dsRNA) before the induction of interferon and prior to transcription of interferon-stimulated antiviral genes. These findings challenge the notion that activation of the OAS-RNase L pathway requires virus to induce type I IFN, which in turn upregulates OAS gene expression, as well as to provide dsRNA to activate OAS. Our data further suggest that myeloid cells may serve as sentinels to restrict viral replication, thus protecting other cell types from infection.

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