RESUMO
The helicase RIG-I initiates an antiviral immune response after recognition of pathogenic RNA. TRIM25, an E3 ubiquitin ligase, mediates K63-linked ubiquitination of RIG-I, which is crucial for RIG-I downstream signaling and the antiviral innate immune response. The components and mode of the RIG-I-initiated innate signaling remain to be fully understood. Here we identify a novel long noncoding RNA (Lnczc3h7a) that binds to TRIM25 and promotes RIG-I-mediated antiviral innate immune responses. Depletion of Lnczc3h7a impairs RIG-I signaling and the antiviral innate response to RNA viruses in vitro and in vivo. Mechanistically, Lnczc3h7a binds to both TRIM25 and activated RIG-I, serving as a molecular scaffold for stabilization of the RIG-I-TRIM25 complex at the early stage of viral infection. Lnczc3h7a facilitates TRIM25-mediated K63-linked ubiquitination of RIG-I and thus promotes downstream signaling transduction. Our findings reveal that host RNAs can enhance the response of innate immune sensors to foreign RNAs, ensuring effective antiviral defense.
Assuntos
Proteína DEAD-box 58/genética , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Imunidade Inata/genética , RNA Longo não Codificante/genética , Fatores de Transcrição/genética , Animais , Linhagem Celular , Humanos , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/metabolismo , Macrófagos Peritoneais/virologia , Camundongos , Modelos Biológicos , Interferência de RNA , Vírus de RNA/imunologia , Transdução de Sinais , Viroses/genética , Viroses/imunologia , Viroses/metabolismo , Viroses/virologiaRESUMO
Prolonged activation of interferon-STAT1 signaling is closely related to inflammatory autoimmune disorders, and therefore the identification of negative regulators of these pathways is important. Through high-content screening of 115 mouse RING-domain E3 ligases, we identified the E3 ubiquitin ligase RNF2 as a potent inhibitor of interferon-dependent antiviral responses. RNF2 deficiency substantially enhanced interferon-stimulated gene (ISG) expression and antiviral responses. Mechanistically, nuclear RNF2 directly bound to STAT1 after interferon stimulation and increased K33-linked polyubiquitination of the DNA-binding domain of STAT1 at position K379, in addition to promoting the disassociation of STAT1/STAT2 from DNA and consequently suppressing ISG transcription. Our study provides insight into the regulation of interferon-dependent responses via a previously unrecognized post-translational modification of STAT1 in the nucleus.
Assuntos
DNA/metabolismo , Interferon Tipo I/farmacologia , Lisina/metabolismo , Complexo Repressor Polycomb 1/metabolismo , Fator de Transcrição STAT1/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Antivirais/farmacologia , Linhagem Celular , Expressão Gênica/efeitos dos fármacos , Lisina/genética , Macrófagos/metabolismo , Macrófagos/virologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Complexo Repressor Polycomb 1/genética , Ligação Proteica/efeitos dos fármacos , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT2/genética , Fator de Transcrição STAT2/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitinação/efeitos dos fármacos , Estomatite Vesicular/genética , Estomatite Vesicular/prevenção & controle , Estomatite Vesicular/virologia , Vírus da Estomatite Vesicular Indiana/fisiologiaRESUMO
OBJECTIVE: To characterize the complete genome sequence of coxsackievirus B5 (CVB5)A210/KM/09 strain which was isolated from Yunnan, China, 2009. METHODS: Eight overlapping clones covering the whole viral genome (excluding the poly-A tail)were obtained by RT-PCR and sequenced, with their nucleotide and amino acid sequences compared with other known CVB5 strains. RESULTS: The genome of the CVB5 A210/KM/09 strain had 7 372 nucleotides in length, and containing a 742-nt non-translated region (NTR) at the 5' end and a 98-nt NTR at the 3' end. The entire open reading frame contained 6 555 nt, encoding a 2 185-aa polyprotein. In the coding region, there appeared no nucleotide deletion or insertion, but some changes of amino acid seemed unique. Based on the complete genome sequence alignments, CVB5 isolate A210/KM/09 strain showed the highest nucleotide (92.5%) and amino acid (97.3%) identities to the CVB5/CC10/10. It also shared nucleotide (80.1%-92.5%) and amino acid (95.0%-97.3%) homology with other CVB5 strains: 17Y, 19CSF, 20CSF, 1954/85/US, 2000/CSF/KOR, 03001N, CoxB5/Henan/2010, VB5/SD/09 and Faulkner. Blast between genome fragments, A210/KM/09 showed similarity on nucleotide (80.1%-92.5%) and amino acid (95.0%-97.3%) identities with other CVB5 strains. The phylogenetic tree, constructed on the complete VP1 regions, indicated that CVB5 could be divided into genotype A, B, C and D. while Genotype C and D could be further divided into C1-C4 and D1-D4 subgenotypes. CONCLUSION: A210/KM/09 and other CVB5 predominant strains isolated in China belonged to CVB5 subgenotype C4.