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1.
Immunity ; 54(9): 1909-1911, 2021 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-34525334

RESUMEN

Some RNAs can assume a Z conformation, an unusual, left-handed turn. In this issue of Immunity, three studies report that mutations in the Zα-RNA binding domain of the adenosine deaminase ADAR1 are sufficient to induce autoinflammatory disease in mice, which models human Aicardí-Goutières syndrome, highlighting the important role of Z-RNA editing in limiting innate immune recognition of endogenous RNA.


Asunto(s)
Enfermedades Autoinmunes del Sistema Nervioso , ARN , Adenosina Desaminasa/genética , Adenosina Desaminasa/metabolismo , Animales , Ratones , ARN/genética , Edición de ARN , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo
2.
Mol Cell ; 82(19): 3712-3728.e10, 2022 10 06.
Artículo en Inglés | MEDLINE | ID: mdl-36150385

RESUMEN

Recognition of pathogen-derived foreign nucleic acids is central to innate immune defense. This requires discrimination between structurally highly similar self and nonself nucleic acids to avoid aberrant inflammatory responses as in the autoinflammatory disorder Aicardi-Goutières syndrome (AGS). How vast amounts of self RNA are shielded from immune recognition to prevent autoinflammation is not fully understood. Here, we show that human SAM-domain- and HD-domain-containing protein 1 (SAMHD1), one of the AGS-causing genes, functions as a single-stranded RNA (ssRNA) 3'exonuclease, the lack of which causes cellular RNA accumulation. Increased ssRNA in cells leads to dissolution of RNA-protein condensates, which sequester immunogenic double-stranded RNA (dsRNA). Release of sequestered dsRNA from condensates triggers activation of antiviral type I interferon via retinoic-acid-inducible gene I-like receptors. Our results establish SAMHD1 as a key regulator of cellular RNA homeostasis and demonstrate that buffering of immunogenic self RNA by condensates regulates innate immune responses.


Asunto(s)
Interferón Tipo I , ARN Bicatenario , Antivirales , Enfermedades Autoinmunes del Sistema Nervioso , Exonucleasas/genética , Humanos , Inmunidad Innata/genética , Interferón Tipo I/genética , Malformaciones del Sistema Nervioso , ARN Bicatenario/genética , Proteína 1 que Contiene Dominios SAM y HD/genética
3.
Immunity ; 52(4): 591-605.e6, 2020 04 14.
Artículo en Inglés | MEDLINE | ID: mdl-32294405

RESUMEN

Human toll-like receptor 8 (TLR8) activation induces a potent T helper-1 (Th1) cell response critical for defense against intracellular pathogens, including protozoa. The receptor harbors two distinct binding sites, uridine and di- and/or trinucleotides, but the RNases upstream of TLR8 remain poorly characterized. We identified two endolysosomal endoribonucleases, RNase T2 and RNase 2, that act synergistically to release uridine from oligoribonucleotides. RNase T2 cleaves preferentially before, and RNase 2 after, uridines. Live bacteria, P. falciparum-infected red blood cells, purified pathogen RNA, and synthetic oligoribonucleotides all required RNase 2 and T2 processing to activate TLR8. Uridine supplementation restored RNA recognition in RNASE2-/- or RNASET2-/- but not RNASE2-/-RNASET2-/- cells. Primary immune cells from RNase T2-hypomorphic patients lacked a response to bacterial RNA but responded robustly to small-molecule TLR8 ligands. Our data identify an essential function of RNase T2 and RNase 2 upstream of TLR8 and provide insight into TLR8 activation.


Asunto(s)
Endorribonucleasas/metabolismo , Monocitos/inmunología , Neutrófilos/inmunología , ARN Bacteriano/metabolismo , ARN Protozoario/metabolismo , Receptor Toll-Like 8/metabolismo , Sistemas CRISPR-Cas , Línea Celular , Endorribonucleasas/inmunología , Eritrocitos/inmunología , Eritrocitos/parasitología , Escherichia coli/química , Escherichia coli/inmunología , Edición Génica/métodos , Humanos , Listeria monocytogenes/química , Listeria monocytogenes/inmunología , Monocitos/microbiología , Monocitos/parasitología , Neutrófilos/microbiología , Neutrófilos/parasitología , Plasmodium falciparum/química , Plasmodium falciparum/inmunología , Cultivo Primario de Células , Estabilidad del ARN , ARN Bacteriano/inmunología , ARN Protozoario/inmunología , Serratia marcescens/química , Serratia marcescens/inmunología , Staphylococcus aureus/química , Staphylococcus aureus/inmunología , Streptococcus/química , Streptococcus/inmunología , Células THP-1 , Receptor Toll-Like 8/inmunología
4.
Cell ; 153(5): 1094-107, 2013 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-23647843

RESUMEN

Recent studies identified cyclic GMP-AMP (cGAMP) as a metazoan second messenger triggering an interferon response. cGAMP is generated from GTP and ATP by cytoplasmic dsDNA sensor cGAMP synthase (cGAS). We combined structural, chemical, biochemical, and cellular assays to demonstrate that this second messenger contains G(2',5')pA and A(3',5')pG phosphodiester linkages, designated c[G(2',5')pA(3',5')p]. We show that, upon dsDNA binding, cGAS is activated through conformational transitions, resulting in formation of a catalytically competent and accessible nucleotide-binding pocket for generation of c[G(2',5')pA(3',5')p]. We demonstrate that cyclization occurs in a stepwise manner through initial generation of 5'-pppG(2',5')pA prior to cyclization to c[G(2',5')pA(3',5')p], with the latter positioned precisely in the catalytic pocket. Mutants of cGAS dsDNA-binding or catalytic pocket residues exhibit reduced or abrogated activity. Our studies have identified c[G(2',5')pA(3',5')p] as a founding member of a family of metazoan 2',5'-containing cyclic heterodinucleotide second messengers distinct from bacterial 3',5' cyclic dinucleotides.


Asunto(s)
Fosfatos de Dinucleósidos/metabolismo , Nucleótidos Cíclicos/metabolismo , Nucleotidiltransferasas/química , Sistemas de Mensajero Secundario , 2',5'-Oligoadenilato Sintetasa/química , Adenosina Trifosfato/metabolismo , Secuencia de Aminoácidos , Animales , Cristalografía por Rayos X , ADN/química , ADN/metabolismo , Guanosina Trifosfato/metabolismo , Humanos , Ratones , Modelos Químicos , Modelos Moleculares , Datos de Secuencia Molecular , Nucleotidiltransferasas/metabolismo , Alineación de Secuencia
5.
Cell ; 154(4): 748-62, 2013 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-23910378

RESUMEN

Binding of dsDNA by cyclic GMP-AMP (cGAMP) synthase (cGAS) triggers formation of the metazoan second messenger c[G(2',5')pA(3',5')p], which binds the signaling protein STING with subsequent activation of the interferon (IFN) pathway. We show that human hSTING(H232) adopts a "closed" conformation upon binding c[G(2',5')pA(3',5')p] and its linkage isomer c[G(2',5')pA(2',5')p], as does mouse mSting(R231) on binding c[G(2',5')pA(3',5')p], c[G(3',5')pA(3',5')p] and the antiviral agent DMXAA, leading to similar "closed" conformations. Comparing hSTING to mSting, 2',5'-linkage-containing cGAMP isomers were more specific triggers of the IFN pathway compared to the all-3',5'-linkage isomer. Guided by structural information, we identified a unique point mutation (S162A) placed within the cyclic-dinucleotide-binding site of hSTING that rendered it sensitive to the otherwise mouse-specific drug DMXAA, a conclusion validated by binding studies. Our structural and functional analysis highlights the unexpected versatility of STING in the recognition of natural and synthetic ligands within a small-molecule pocket created by the dimerization of STING.


Asunto(s)
Antivirales/farmacología , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Nucleótidos Cíclicos/metabolismo , Xantonas/farmacología , Animales , Cristalografía por Rayos X , GMP Cíclico/metabolismo , Humanos , Factor 3 Regulador del Interferón/metabolismo , Interferón Tipo I/metabolismo , Proteínas de la Membrana/antagonistas & inhibidores , Proteínas de la Membrana/genética , Ratones , Modelos Moleculares , Mutagénesis , Conformación Proteica , Transducción de Señal , Relación Estructura-Actividad
6.
Nat Immunol ; 16(10): 1025-33, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26343537

RESUMEN

Cytosolic DNA that emerges during infection with a retrovirus or DNA virus triggers antiviral type I interferon responses. So far, only double-stranded DNA (dsDNA) over 40 base pairs (bp) in length has been considered immunostimulatory. Here we found that unpaired DNA nucleotides flanking short base-paired DNA stretches, as in stem-loop structures of single-stranded DNA (ssDNA) derived from human immunodeficiency virus type 1 (HIV-1), activated the type I interferon-inducing DNA sensor cGAS in a sequence-dependent manner. DNA structures containing unpaired guanosines flanking short (12- to 20-bp) dsDNA (Y-form DNA) were highly stimulatory and specifically enhanced the enzymatic activity of cGAS. Furthermore, we found that primary HIV-1 reverse transcripts represented the predominant viral cytosolic DNA species during early infection of macrophages and that these ssDNAs were highly immunostimulatory. Collectively, our study identifies unpaired guanosines in Y-form DNA as a highly active, minimal cGAS recognition motif that enables detection of HIV-1 ssDNA.


Asunto(s)
ADN Complementario/química , ADN Viral/química , ADN Viral/inmunología , VIH-1/genética , VIH-1/inmunología , Interferón-alfa/inmunología , Nucleotidiltransferasas/genética , Animales , Línea Celular , Células Cultivadas , ADN Complementario/genética , ADN Complementario/inmunología , ADN Viral/genética , Células HEK293 , Humanos , Inmunización , Ratones
7.
Nucleic Acids Res ; 51(21): 11893-11910, 2023 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-37831086

RESUMEN

RIG-I is a cytosolic receptor of viral RNA essential for the immune response to numerous RNA viruses. Accordingly, RIG-I must sensitively detect viral RNA yet tolerate abundant self-RNA species. The basic binding cleft and an aromatic amino acid of the RIG-I C-terminal domain(CTD) mediate high-affinity recognition of 5'triphosphorylated and 5'base-paired RNA(dsRNA). Here, we found that, while 5'unmodified hydroxyl(OH)-dsRNA demonstrated residual activation potential, 5'-monophosphate(5'p)-termini, present on most cellular RNAs, prevented RIG-I activation. Determination of CTD/dsRNA co-crystal structures and mutant activation studies revealed that the evolutionarily conserved I875 within the CTD sterically inhibits 5'p-dsRNA binding. RIG-I(I875A) was activated by both synthetic 5'p-dsRNA and endogenous long dsRNA within the polyA-rich fraction of total cellular RNA. RIG-I(I875A) specifically interacted with long, polyA-bearing, mitochondrial(mt) RNA, and depletion of mtRNA from total RNA abolished its activation. Altogether, our study demonstrates that avoidance of 5'p-RNA recognition is crucial to prevent mtRNA-triggered RIG-I-mediated autoinflammation.


Asunto(s)
Proteína 58 DEAD Box , Isoleucina , Receptores Inmunológicos , Proteína 58 DEAD Box/química , Proteína 58 DEAD Box/genética , Proteína 58 DEAD Box/metabolismo , Tolerancia Inmunológica , Isoleucina/genética , ARN Bicatenario/genética , ARN Mitocondrial/genética , ARN Mitocondrial/metabolismo , ARN Viral/genética , ARN Viral/metabolismo , Humanos , Receptores Inmunológicos/química , Receptores Inmunológicos/genética , Receptores Inmunológicos/metabolismo
8.
J Med Virol ; 96(6): e29690, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38804180

RESUMEN

Autophagy is a degradational pathway with pivotal roles in cellular homeostasis and survival, including protection of neurons in the central nervous system (CNS). The significance of autophagy as antiviral defense mechanism is recognized and some viruses hijack and modulate this process to their advantage in certain cell types. Here, we present data demonstrating that the human neurotropic herpesvirus varicella zoster virus (VZV) induces autophagy in human SH-SY5Y neuronal cells, in which the pathway exerts antiviral activity. Productively VZV-infected SH-SY5Y cells showed increased LC3-I-LC3-II conversion as well as co-localization of the viral glycoprotein E and the autophagy receptor p62. The activation of autophagy was dependent on a functional viral genome. Interestingly, inducers of autophagy reduced viral transcription, whereas inhibition of autophagy increased viral transcript expression. Finally, the genotype of patients with severe ocular and brain VZV infection were analyzed to identify potential autophagy-associated inborn errors of immunity. Two patients expressing genetic variants in the autophagy genes ULK1 and MAP1LC3B2, respectively, were identified. Notably, cells of both patients showed reduced autophagy, alongside enhanced viral replication and death of VZV-infected cells. In conclusion, these results demonstrate a neuro-protective role for autophagy in the context of VZV infection and suggest that failure to mount an autophagy response is a potential predisposing factor for development of severe VZV disease.


Asunto(s)
Autofagia , Herpesvirus Humano 3 , Neuronas , Humanos , Herpesvirus Humano 3/fisiología , Herpesvirus Humano 3/patogenicidad , Neuronas/virología , Homólogo de la Proteína 1 Relacionada con la Autofagia/metabolismo , Homólogo de la Proteína 1 Relacionada con la Autofagia/genética , Replicación Viral , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Infección por el Virus de la Varicela-Zóster/virología , Proteínas del Envoltorio Viral/genética , Proteínas del Envoltorio Viral/metabolismo , Línea Celular , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Péptidos y Proteínas de Señalización Intracelular/genética , Interacciones Huésped-Patógeno
9.
Immunity ; 43(3): 411-3, 2015 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-26377892

RESUMEN

TREX1 regulates innate immune responses by counteracting DNA accumulation in the cytosol. In this issue of Immunity, Hasan et al. (2015) show that TREX1 also safeguards the cell against free glycan build-up in the endoplasmic reticulum, thereby preventing glycan-induced inflammation.


Asunto(s)
Citosol/enzimología , Exodesoxirribonucleasas/metabolismo , Hexosiltransferasas/metabolismo , Proteínas de la Membrana/metabolismo , Fosfoproteínas/metabolismo , Animales , Humanos
10.
Immunity ; 43(1): 41-51, 2015 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-26187414

RESUMEN

The cytosolic helicase retinoic acid-inducible gene-I (RIG-I) initiates immune responses to most RNA viruses by detecting viral 5'-triphosphorylated RNA (pppRNA). Although endogenous mRNA is also 5'-triphosphorylated, backbone modifications and the 5'-ppp-linked methylguanosine ((m7)G) cap prevent immunorecognition. Here we show that the methylation status of endogenous capped mRNA at the 5'-terminal nucleotide (N1) was crucial to prevent RIG-I activation. Moreover, we identified a single conserved amino acid (H830) in the RIG-I RNA binding pocket as the mediator of steric exclusion of N1-2'O-methylated RNA. H830A alteration (RIG-I(H830A)) restored binding of N1-2'O-methylated pppRNA. Consequently, endogenous mRNA activated the RIG-I(H830A) mutant but not wild-type RIG-I. Similarly, knockdown of the endogenous N1-2'O-methyltransferase led to considerable RIG-I stimulation in the absence of exogenous stimuli. Studies involving yellow-fever-virus-encoded 2'O-methyltransferase and RIG-I(H830A) revealed that viruses exploit this mechanism to escape RIG-I. Our data reveal a new role for cap N1-2'O-methylation in RIG-I tolerance of self-RNA.


Asunto(s)
ARN Helicasas DEAD-box/genética , Tolerancia Inmunológica/genética , Procesamiento Postranscripcional del ARN/genética , ARN/genética , Virus de la Fiebre Amarilla/enzimología , Secuencia de Aminoácidos , Animales , Células Cultivadas , Proteína 58 DEAD Box , Activación Enzimática/genética , Activación Enzimática/inmunología , Histidina/genética , Humanos , Metilación , Metiltransferasas/genética , Ratones , Estructura Terciaria de Proteína , ARN/química , ARN/inmunología , ARN Viral/inmunología , Receptores Inmunológicos , Virus de la Fiebre Amarilla/genética
11.
Clin Immunol ; 256: 109777, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37741518

RESUMEN

C-terminal variants in CDC42 encoding cell division control protein 42 homolog underlie neonatal-onset cytopenia, autoinflammation, rash, and hemophagocytic lymphohistiocytosis (NOCARH). Pyrin inflammasome hyperactivation has been shown to contribute to disease pathophysiology. However, mortality of NOCARH patients remains high despite inflammasome-focused treatments. Here, we demonstrate in four NOCARH patients from three families that cell-intrinsic activation of type I interferon (IFN) is a previously unrecognized driver of autoinflammation in NOCARH. Our data show that aberrant innate immune activation is caused by sensing of cytosolic nucleic acids released from mitochondria, which exhibit disturbances in integrity and dynamics due to CDC42 dysfunction. In one of our patients, treatment with the Janus kinase inhibitor ruxolitinib led to complete remission, indicating that inhibition of type I IFN signaling may have an important role in the management of autoinflammation in patients with NOCARH.


Asunto(s)
Interferón Tipo I , Linfohistiocitosis Hemofagocítica , Humanos , Recién Nacido , Proteína de Unión al GTP cdc42 , Inflamasomas/genética , Linfohistiocitosis Hemofagocítica/etiología , Nitrilos , Síndrome
12.
J Virol ; 96(16): e0055922, 2022 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-35916513

RESUMEN

Intracellular RIG-I receptors represent key innate sensors of RNA virus infection, and RIG-I activation results in the induction of hundreds of host effector genes, including interferon-stimulated genes (ISGs). Synthetic RNA agonists targeting RIG-I have shown promise as antivirals against a broad spectrum of viruses, including influenza A virus (IAV), in both in vitro and mouse models of infection. Herein, we demonstrate that treatment of a ferret airway epithelial (FRL) cell line with a RIG-I agonist rapidly and potently induced expression of a broad range of ISGs and resulted in potent inhibition of growth of different IAV strains. In ferrets, a single intravenous injection of RIG-I agonist was associated with upregulated ISG expression in peripheral blood mononuclear cells and lung tissue, but not in nasal tissues. In a ferret model of viral contact transmission, a single treatment of recipient animals 24 h prior to cohousing with IAV-infected donors did not reduce virus transmission and shedding but did result in reduced lung virus titers 6 days after treatment. A single treatment of the IAV-infected donor animals also resulted in reduced virus titers in the lungs 2 days later. Thus, a single intravenous treatment with RIG-I agonist prior to infection or to ferrets with an established IAV infection can reduce virus growth in the lungs. These findings support further development of RIG-I agonists as effective antiviral treatments to limit the impact of IAV infections, particularly in reducing virus replication in the lower airways. IMPORTANCE RIG-I agonists have shown potential as broad-spectrum antivirals in vitro and in mouse models of infection. However, their antiviral potential has not been reported in outbred animals such as ferrets, which are widely regarded as the gold standard small animal model for human IAV infections. Herein, we demonstrate that RIG-I agonist treatment of a ferret airway cell line resulted in ISG induction and inhibition of a broad range of human influenza viruses. A single intravenous treatment of ferrets also resulted in systemic induction of ISGs, including in lung tissue, and when delivered to animals prior to IAV exposure or to animals with established IAV infection treatment resulted in reduced virus replication in the lungs. These data demonstrate the effectiveness of single RIG-I treatment against IAV in the ferret model and highlight the importance of future studies to optimize treatment regimens and delivery routes to maximize their ability to ameliorate IAV infections.


Asunto(s)
Virus de la Influenza A , Gripe Humana , Animales , Antivirales/farmacología , Hurones/metabolismo , Humanos , Inmunidad Innata , Virus de la Influenza A/genética , Interferones/metabolismo , Leucocitos Mononucleares/metabolismo , Pulmón , Ratones , Replicación Viral/genética
13.
Proc Natl Acad Sci U S A ; 117(32): 19475-19486, 2020 08 11.
Artículo en Inglés | MEDLINE | ID: mdl-32709741

RESUMEN

The DNA sensor cGAS catalyzes the production of the cyclic dinucleotide cGAMP, resulting in type I interferon responses. We addressed the functionality of cGAS-mediated DNA sensing in human and murine T cells. Activated primary CD4+ T cells expressed cGAS and responded to plasmid DNA by upregulation of ISGs and release of bioactive interferon. In mouse T cells, cGAS KO ablated sensing of plasmid DNA, and TREX1 KO enabled cells to sense short immunostimulatory DNA. Expression of IFIT1 and MX2 was downregulated and upregulated in cGAS KO and TREX1 KO T cell lines, respectively, compared to parental cells. Despite their intact cGAS sensing pathway, human CD4+ T cells failed to mount a reverse transcriptase (RT) inhibitor-sensitive immune response following HIV-1 infection. In contrast, infection of human T cells with HSV-1 that is functionally deficient for the cGAS antagonist pUL41 (HSV-1ΔUL41N) resulted in a cGAS-dependent type I interferon response. In accordance with our results in primary CD4+ T cells, plasmid challenge or HSV-1ΔUL41N inoculation of T cell lines provoked an entirely cGAS-dependent type I interferon response, including IRF3 phosphorylation and expression of ISGs. In contrast, no RT-dependent interferon response was detected following transduction of T cell lines with VSV-G-pseudotyped lentiviral or gammaretroviral particles. Together, T cells are capable to raise a cGAS-dependent cell-intrinsic response to both plasmid DNA challenge or inoculation with HSV-1ΔUL41N. However, HIV-1 infection does not appear to trigger cGAS-mediated sensing of viral DNA in T cells, possibly by revealing viral DNA of insufficient quantity, length, and/or accessibility to cGAS.


Asunto(s)
Linfocitos T CD4-Positivos/virología , VIH-1/fisiología , Interferón Tipo I/metabolismo , Nucleotidiltransferasas/metabolismo , Animales , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Células Cultivadas , ADN Viral/fisiología , Exodesoxirribonucleasas/genética , Exodesoxirribonucleasas/metabolismo , Herpesvirus Humano 1/fisiología , Interacciones Huésped-Patógeno , Humanos , Inmunidad Innata , Factor 3 Regulador del Interferón/metabolismo , Ratones , Nucleotidiltransferasas/genética , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Fosforilación , Especificidad de la Especie , Replicación Viral
14.
J Infect Dis ; 226(12): 2079-2088, 2022 12 13.
Artículo en Inglés | MEDLINE | ID: mdl-35861054

RESUMEN

Infections caused by human respiratory syncytial virus (RSV) are associated with substantial rates of morbidity and mortality. Treatment options are limited, and there is urgent need for the development of efficient antivirals. Pattern recognition receptors such as the cytoplasmic helicase retinoic acid-inducible gene (RIG) I can be activated by viral nucleic acids, leading to activation of interferon-stimulated genes and generation of an "antiviral state." In the current study, we activated RIG-I with synthetic RNA agonists (3pRNA) to induce resistance to RSV infection in vitro and in vivo. In vitro, pretreatment of human, mouse, and ferret airway cell lines with RIG-I agonist before RSV exposure inhibited virus infection and replication. Moreover, a single intravenous injection of 3pRNA 1 day before RSV infection resulted in potent inhibition of virus replication in the lungs of mice and ferrets, but not in nasal tissues. These studies provide evidence that RIG-I agonists represent a promising antiviral drug for RSV prophylaxis.


Asunto(s)
Infecciones por Virus Sincitial Respiratorio , Virus Sincitial Respiratorio Humano , Animales , Humanos , Virus Sincitial Respiratorio Humano/fisiología , Hurones , Pulmón , Replicación Viral , Antivirales/farmacología , Tretinoina
15.
J Clin Immunol ; 42(2): 325-335, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34783940

RESUMEN

PURPOSE: NLRC4-associated autoinflammatory disease (NLRC4-AID) is an autosomal dominant condition presenting with a range of clinical manifestations which can include macrophage activation syndrome (MAS) and severe enterocolitis. We now report the first homozygous mutation in NLRC4 (c.478G > A, p.A160T) causing autoinflammatory disease with immune dysregulation and find that heterozygous carriers in the general population are at increased risk of developing ulcerative colitis. METHODS: Circulating immune cells and inflammatory markers were profiled and historical clinical data interrogated. DNA was extracted and sequenced using standard procedures. Inflammasome activation assays for ASC speck formation, pyroptosis, and IL-1ß/IL-18 secretion confirmed pathogenicity of the mutation in vitro. Genome-wide association of NLRC4 (A160T) with ulcerative colitis was examined using data from the IBD exomes portal. RESULTS: A 60-year-old Brazilian female patient was evaluated for recurrent episodes of systemic inflammation from six months of age. Episodes were characterized by recurrent low-grade fever, chills, oral ulceration, uveitis, arthralgia, and abdominal pain, followed by diarrhea with mucus and variable skin rash. High doses of corticosteroids were somewhat effective in controlling disease and anti-IL-1ß therapy partially controlled symptoms. While on treatment, serum IL-1ß and IL-18 levels remained elevated. Genetic investigations identified a homozygous mutation in NLRC4 (A160T), inherited in a recessive fashion. Increased ASC speck formation and IL-1ß/IL-18 secretion confirmed pathogenicity when NLRC4 (A160T) was analyzed in human cell lines. This allele is significantly enriched in patients with ulcerative colitis: OR 2.546 (95% 1.778-3.644), P = 0.01305. CONCLUSION: NLRC4 (A160T) can either cause recessively inherited autoinflammation and immune dysregulation, or function as a heterozygous risk factor for the development of ulcerative colitis.


Asunto(s)
Colitis Ulcerosa , Enfermedades Autoinflamatorias Hereditarias , Proteínas Adaptadoras de Señalización CARD/genética , Proteínas Adaptadoras de Señalización CARD/metabolismo , Proteínas de Unión al Calcio/genética , Colitis Ulcerosa/diagnóstico , Colitis Ulcerosa/genética , Femenino , Estudio de Asociación del Genoma Completo , Humanos , Inflamasomas/metabolismo , Persona de Mediana Edad
16.
Immunity ; 39(3): 482-95, 2013 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-23993650

RESUMEN

Immune sensing of DNA is critical for antiviral immunity but can also trigger autoimmune diseases such as lupus erythematosus (LE). Here we have provided evidence for the involvement of a damage-associated DNA modification in the detection of cytosolic DNA. The oxidized base 8-hydroxyguanosine (8-OHG), a marker of oxidative damage in DNA, potentiated cytosolic immune recognition by decreasing its susceptibility to 3' repair exonuclease 1 (TREX1)-mediated degradation. Oxidizative modifications arose physiologically in pathogen DNA during lysosomal reactive oxygen species (ROS) exposure, as well as in neutrophil extracellular trap (NET) DNA during the oxidative burst. 8-OHG was also abundant in UV-exposed skin lesions of LE patients and colocalized with type I interferon (IFN). Injection of oxidized DNA in the skin of lupus-prone mice induced lesions that closely matched respective lesions in patients. Thus, oxidized DNA represents a prototypic damage-associated molecular pattern (DAMP) with important implications for infection, sterile inflammation, and autoimmunity.


Asunto(s)
Daño del ADN , ADN/metabolismo , Exodesoxirribonucleasas/metabolismo , Proteínas de la Membrana/metabolismo , Fosfoproteínas/metabolismo , Animales , Células Cultivadas , Reparación del ADN , Guanosina/análogos & derivados , Guanosina/metabolismo , Humanos , Interferón Tipo I , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/inmunología , Lupus Eritematoso Sistémico/metabolismo , Ratones , Ratones Endogámicos C57BL , Neutrófilos/metabolismo , Oxidación-Reducción , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismo
17.
J Virol ; 93(24)2019 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-31597782

RESUMEN

When expressed in virus-producing cells, the cellular multipass transmembrane protein SERINC5 reduces the infectivity of HIV-1 particles and is counteracted by HIV-1 Nef. Due to the unavailability of an antibody of sufficient specificity and sensitivity, investigation of SERINC5 protein expression and subcellular localization has been limited to heterologously expressed SERINC5. We generated, via CRISPR/Cas9-assisted gene editing, Jurkat T-cell clones expressing endogenous SERINC5 bearing an extracellularly exposed hemagglutinin (HA) epitope [Jurkat SERINC5(iHA knock-in) T cells]. This modification enabled quantification of endogenous SERINC5 protein levels and demonstrated a predominant localization in lipid rafts. Interferon alpha (IFN-α) treatment enhanced cell surface levels of SERINC5 in a ruxolitinib-sensitive manner in the absence of modulation of mRNA and protein quantities. Parental and SERINC5(iHA knock-in) T cells shared the ability to produce infectious wild-type HIV-1 but not an HIV-1 Δnef mutant. SERINC5-imposed reduction of infectivity involved a modest reduction of virus fusogenicity. An association of endogenous SERINC5 protein with HIV-1 Δnef virions was consistently detectable as a 35-kDa species, as opposed to heterologous SERINC5, which presented as a 51-kDa species. Nef-mediated functional counteraction did not correlate with virion exclusion of SERINC5, arguing for the existence of additional counteractive mechanisms of Nef that act on virus-associated SERINC5. In HIV-1-infected cells, Nef triggered the internalization of SERINC5 in the absence of detectable changes of steady-state protein levels. These findings establish new properties of endogenous SERINC5 expression and subcellular localization, challenge existing concepts of HIV-1 Nef-mediated antagonism of SERINC5, and uncover an unprecedented role of IFN-α in modulating SERINC5 through accumulation at the cell surface.IMPORTANCE SERINC5 is the long-searched-for antiviral factor that is counteracted by the HIV-1 accessory gene product Nef. Here, we engineered, via CRISPR/Cas9 technology, T-cell lines that express endogenous SERINC5 alleles tagged with a knocked-in HA epitope. This genetic modification enabled us to study basic properties of endogenous SERINC5 and to verify proposed mechanisms of HIV-1 Nef-mediated counteraction of SERINC5. Using this unique resource, we identified the susceptibility of endogenous SERINC5 protein to posttranslational modulation by type I IFNs and suggest uncoupling of Nef-mediated functional antagonism from SERINC5 exclusion from virions.


Asunto(s)
Fármacos Anti-VIH/farmacología , VIH-1/efectos de los fármacos , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/farmacología , Sistemas CRISPR-Cas , Línea Celular , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Edición Génica , Regulación de la Expresión Génica , Técnicas de Inactivación de Genes , Genotipo , Células HEK293 , Infecciones por VIH/virología , Interacciones Huésped-Patógeno/fisiología , Humanos , Interferón-alfa , Proteínas de la Membrana/genética , Nitrilos , Pirazoles/farmacología , Pirimidinas , Linfocitos T/virología , Virión/metabolismo , Productos del Gen nef del Virus de la Inmunodeficiencia Humana/genética , Productos del Gen nef del Virus de la Inmunodeficiencia Humana/metabolismo
18.
PLoS Pathog ; 14(8): e1007269, 2018 08.
Artículo en Inglés | MEDLINE | ID: mdl-30125328

RESUMEN

SERINC5 is a host restriction factor that impairs infectivity of HIV-1 and other primate lentiviruses and is counteracted by the viral accessory protein Nef. However, the importance of SERINC5 antagonism for viral replication and cytopathicity remained unclear. Here, we show that the Nef protein of the highly divergent SIVcol lineage infecting mantled guerezas (Colobus guereza) is a potent antagonist of SERINC5, although it lacks the CD4, CD3 and CD28 down-modulation activities exerted by other primate lentiviral Nefs. In addition, SIVcol Nefs decrease CXCR4 cell surface expression, suppress TCR-induced actin remodeling, and counteract Colobus but not human tetherin. Unlike HIV-1 Nef proteins, SIVcol Nef induces efficient proteasomal degradation of SERINC5 and counteracts orthologs from highly divergent vertebrate species, such as Xenopus frogs and zebrafish. A single Y86F mutation disrupts SERINC5 and tetherin antagonism but not CXCR4 down-modulation by SIVcol Nef, while mutation of a C-proximal di-leucine motif has the opposite effect. Unexpectedly, the Y86F change in SIVcol Nef had little if any effect on viral replication and CD4+ T cell depletion in preactivated human CD4+ T cells and in ex vivo infected lymphoid tissue. However, SIVcol Nef increased virion infectivity up to 10-fold and moderately increased viral replication in resting peripheral blood mononuclear cells (PBMCs) that were first infected with HIV-1 and activated three or six days later. In conclusion, SIVcol Nef lacks several activities that are conserved in other primate lentiviruses and utilizes a distinct proteasome-dependent mechanism to counteract SERINC5. Our finding that evolutionarily distinct SIVcol Nefs show potent anti-SERINC5 activity supports a relevant role of SERINC5 antagonism for viral fitness in vivo. Our results further suggest this Nef function is particularly important for virion infectivity under conditions of limited CD4+ T cell activation.


Asunto(s)
Linfocitos T CD4-Positivos/virología , Productos del Gen nef/fisiología , VIH-1/fisiología , Tejido Linfoide/virología , Proteínas de la Membrana/metabolismo , Replicación Viral/genética , Animales , Linfocitos T CD4-Positivos/metabolismo , Células Cultivadas , Colobus/virología , Células HEK293 , Humanos , Células Jurkat , Proteínas de la Membrana/genética , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Virus de la Inmunodeficiencia de los Simios/genética
19.
Nature ; 514(7522): 372-375, 2014 10 16.
Artículo en Inglés | MEDLINE | ID: mdl-25119032

RESUMEN

Mammalian cells possess mechanisms to detect and defend themselves from invading viruses. In the cytosol, the RIG-I-like receptors (RLRs), RIG-I (retinoic acid-inducible gene I; encoded by DDX58) and MDA5 (melanoma differentiation-associated gene 5; encoded by IFIH1) sense atypical RNAs associated with virus infection. Detection triggers a signalling cascade via the adaptor MAVS that culminates in the production of type I interferons (IFN-α and ß; hereafter IFN), which are key antiviral cytokines. RIG-I and MDA5 are activated by distinct viral RNA structures and much evidence indicates that RIG-I responds to RNAs bearing a triphosphate (ppp) moiety in conjunction with a blunt-ended, base-paired region at the 5'-end (reviewed in refs 1, 2, 3). Here we show that RIG-I also mediates antiviral responses to RNAs bearing 5'-diphosphates (5'pp). Genomes from mammalian reoviruses with 5'pp termini, 5'pp-RNA isolated from yeast L-A virus, and base-paired 5'pp-RNAs made by in vitro transcription or chemical synthesis, all bind to RIG-I and serve as RIG-I agonists. Furthermore, a RIG-I-dependent response to 5'pp-RNA is essential for controlling reovirus infection in cultured cells and in mice. Thus, the minimal determinant for RIG-I recognition is a base-paired RNA with 5'pp. Such RNAs are found in some viruses but not in uninfected cells, indicating that recognition of 5'pp-RNA, like that of 5'ppp-RNA, acts as a powerful means of self/non-self discrimination by the innate immune system.


Asunto(s)
ARN Helicasas DEAD-box/metabolismo , Difosfatos/metabolismo , Inmunidad Innata , ARN Viral/química , ARN Viral/metabolismo , Reoviridae/genética , Reoviridae/inmunología , Animales , Emparejamiento Base , Secuencia de Bases , Proteína 58 DEAD Box , Femenino , Genoma Viral/genética , Masculino , Ratones , ARN Viral/genética , Reoviridae/fisiología
20.
Eur J Immunol ; 48(4): 605-611, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29215161

RESUMEN

Type I interferon (IFN) is a critical mediator of autoimmune diseases such as systemic lupus erythematosus (SLE) and Aicardi-Goutières Syndrome (AGS). The recently discovered cyclic-GMP-AMP (cGAMP) synthase (cGAS) induces the production of type I IFN in response to cytosolic DNA and is potentially linked to SLE and AGS. Suppressive oligodeoxynucleotides (ODN) containing repetitive TTAGGG motifs present in mammalian telomeres have proven useful in the treatment of autoimmune diseases including SLE. In this study, we demonstrate that the suppressive ODN A151 effectively inhibits activation of cGAS in response to cytosolic DNA, thereby inhibiting type I IFN production by human monocytes. In addition, A151 abrogated cGAS activation in response to endogenous accumulation of DNA using TREX1-deficient monocytes. We demonstrate that A151 prevents cGAS activation in a manner that is competitive with DNA. This suppressive activity of A151 was dependent on both telomeric sequence and phosphorothioate backbone. To our knowledge this report presents the first cGAS inhibitor capable of blocking self-DNA. Collectively, these findings might lead to the development of new therapeutics against IFN-driven pathologies due to cGAS activation.


Asunto(s)
Interferón Tipo I/biosíntesis , Monocitos/inmunología , Motivos de Nucleótidos/genética , Nucleotidiltransferasas/antagonistas & inhibidores , Oligodesoxirribonucleótidos/genética , Oligonucleótidos/genética , Línea Celular , Citosol , ADN/genética , Exodesoxirribonucleasas/genética , Células HEK293 , Humanos , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/inmunología , Fosfoproteínas/genética , Telómero/genética
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