Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Filtrar
1.
Nucleic Acids Res ; 51(21): 11893-11910, 2023 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-37831086

RESUMO

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.


Assuntos
Proteína DEAD-box 58 , Isoleucina , Receptores Imunológicos , Proteína DEAD-box 58/química , Proteína DEAD-box 58/genética , Proteína DEAD-box 58/metabolismo , Tolerância Imunológica , Isoleucina/genética , RNA de Cadeia Dupla/genética , RNA Mitocondrial/genética , RNA Mitocondrial/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , Humanos , Receptores Imunológicos/química , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo
2.
Immunity ; 43(1): 41-51, 2015 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-26187414

RESUMO

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.


Assuntos
RNA Helicases DEAD-box/genética , Tolerância Imunológica/genética , Processamento Pós-Transcricional do RNA/genética , RNA/genética , Vírus da Febre Amarela/enzimologia , Sequência de Aminoácidos , Animais , Células Cultivadas , Proteína DEAD-box 58 , Ativação Enzimática/genética , Ativação Enzimática/imunologia , Histidina/genética , Humanos , Metilação , Metiltransferases/genética , Camundongos , Estrutura Terciária de Proteína , RNA/química , RNA/imunologia , RNA Viral/imunologia , Receptores Imunológicos , Vírus da Febre Amarela/genética
3.
Mol Ther ; 25(9): 2093-2103, 2017 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-28760668

RESUMO

Influenza A virus infection causes substantial morbidity and mortality in seasonal epidemic outbreaks, and more efficient treatments are urgently needed. Innate immune sensing of viral nucleic acids stimulates antiviral immunity, including cell-autonomous antiviral defense mechanisms that restrict viral replication. RNA oligonucleotide ligands that potently activate the cytoplasmic helicase retinoic-acid-inducible gene I (RIG-I) are promising candidates for the development of new antiviral therapies. Here, we demonstrate in an Mx1-expressing mouse model of influenza A virus infection that a single intravenous injection of low-dose RIG-I ligand 5'-triphosphate RNA (3pRNA) completely protected mice from a lethal challenge with influenza A virus for at least 7 days. Furthermore, systemic administration of 3pRNA rescued mice with pre-established fulminant influenza infection and prevented the fatal effects of a streptococcal superinfection. Type I interferon, but not interferon-λ, was required for the therapeutic effect. Our results suggest that the use of RIG-I activating oligonucleotide ligands has the clinical potential to confine influenza epidemics when a strain-specific vaccine is not yet available and to reduce lethality of influenza in severely infected patients.


Assuntos
Infecções Bacterianas , Vírus da Influenza A , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Infecções por Orthomyxoviridae/metabolismo , Infecções por Orthomyxoviridae/virologia , Superinfecção , Animais , Quimiocina CXCL10/metabolismo , Vírus da Influenza A/imunologia , Interferon Tipo I/metabolismo , Ligantes , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Pulmão/virologia , Proteínas de Membrana/agonistas , Camundongos , Camundongos Transgênicos , Proteínas do Tecido Nervoso/agonistas , Oligonucleotídeos/administração & dosagem , Oligonucleotídeos/genética , Infecções por Orthomyxoviridae/mortalidade , Substâncias Protetoras/administração & dosagem , RNA/administração & dosagem , RNA/genética , Receptores de Superfície Celular , Análise de Sobrevida , Receptores Toll-Like/metabolismo
4.
Nat Commun ; 14(1): 4253, 2023 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-37474523

RESUMO

Immune checkpoint blockade therapy is beneficial and even curative for some cancer patients. However, the majority don't respond to immune therapy. Across different tumor types, pre-existing T cell infiltrates predict response to checkpoint-based immunotherapy. Based on in vitro pharmacological studies, mouse models and analyses of human melanoma patients, we show that the cytokine GDF-15 impairs LFA-1/ß2-integrin-mediated adhesion of T cells to activated endothelial cells, which is a pre-requisite of T cell extravasation. In melanoma patients, GDF-15 serum levels strongly correlate with failure of PD-1-based immune checkpoint blockade therapy. Neutralization of GDF-15 improves both T cell trafficking and therapy efficiency in murine tumor models. Thus GDF-15, beside its known role in cancer-related anorexia and cachexia, emerges as a regulator of T cell extravasation into the tumor microenvironment, which provides an even stronger rationale for therapeutic anti-GDF-15 antibody development.


Assuntos
Melanoma , Linfócitos T , Humanos , Camundongos , Animais , Linfócitos T/patologia , Antígeno-1 Associado à Função Linfocitária , Células Endoteliais/patologia , Inibidores de Checkpoint Imunológico/farmacologia , Inibidores de Checkpoint Imunológico/uso terapêutico , Melanoma/patologia , Imunoterapia , Microambiente Tumoral
5.
Oncoimmunology ; 5(10): e1219827, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27853642

RESUMO

Activation of the innate immune receptor retinoic acid-inducible gene I (RIG-I) by its specific ligand 5'-triphosphate-RNA (3pRNA) triggers antitumor immunity predominantly via NK cell activation and direct apoptosis induction in tumor cells. However, how NK cells are mobilized to attack the tumor cells remains elusive. Here, we show that RIG-I activation induced the secretion of extracellular vesicles (EVs) from melanoma cells, which by themselves revealed antitumor activity in vitro and in vivo. RIG-I-induced EVs from melanoma cells exhibited an increased expression of the NKp30-ligand (BAG6, BAT3) on their surface triggering NK cell-mediated lysis of melanoma cells via activation of the cytotoxicity NK cell-receptor NKp30. Moreover, systemic administration of RIG-I-induced melanoma-EVs showed a potent antitumor activity in a melanoma mouse model in vivo. In conclusion, our data establish a new RIG-I-dependent pathway leading to NK cell-mediated tumor cell killing.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA