Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Virus Res ; 252: 48-57, 2018 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-29782878

RESUMO

Many viruses make use of, and even direct, the ubiquitin-proteasome system to facilitate the generation of a cellular environment favorable for virus replication, while host cells use selected protein ubiquitylation pathways for antiviral defense. Relatively little information has been acquired, however, regarding the extent to which protein ubiquitylation determines the replication success of picornaviruses. Here we report that the ubiquitin-protein ligase E6AP/UBE3A, recently shown to be a participant in encephalomyocarditis virus (EMCV) 3C protease concentration regulation, also facilitates the early stages of EMCV replication, probably by a mechanism that does not involve 3C protease ubiquitylation. Using stably transfected E6AP knockdown cells, we found that reduced E6AP concentration extends the time required for infected cells to undergo the morphological changes caused by virally induced pathogenesis and to begin the production of infectious virions. This lag in virion production is accompanied by a corresponding delay in the appearance of detectable levels of viral proteins and RNA. We also found, by using both immunofluorescence microscopy and cell fractionation, that E6AP is partially redistributed from the nucleus to the cytoplasm in EMCV-infected cells, thereby increasing its availability to participate in cytoplasmic virus replication processes.


Assuntos
Vírus da Encefalomiocardite/fisiologia , Ubiquitina-Proteína Ligases/genética , Replicação Viral , Animais , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Citoplasma/virologia , Replicação do DNA , Imunofluorescência , Interações Hospedeiro-Patógeno , Camundongos , Células NIH 3T3 , Ubiquitinação
2.
Biochem Biophys Res Commun ; 494(1-2): 63-69, 2017 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-29054411

RESUMO

The encephalomyocarditis virus (EMCV) 3C protease (3Cpro) is one of a small number of viral proteins whose concentration is known to be regulated by the cellular ubiquitin-proteasome system. Here we report that the ubiquitin-conjugating enzyme UbcH7/UBE2L3 and the ubiquitin-protein ligase E6AP/UBE3A are components of a previously unknown EMCV 3Cpro-polyubiquitylating pathway. Following the identification of UbcH7/UBE2L3 as a participant in 3Cpro ubiquitylation, we purified a UbcH7-dependent 3Cpro-ubiquitylating activity from mouse cells, which we identified as E6AP. In vitro reconstitution assays demonstrated that E6AP catalyzes the synthesis of 3Cpro-attached Lys48-linked ubiquitin chains, known to be recognized by the 26S proteasome. We found that the 3Cpro accumulates to higher levels in EMCV-infected E6AP knockdown cells than in control cells, indicating a role for E6AP in in vivo 3Cpro concentration regulation. We also discovered that ARIH1 functions with UbcH7 to catalyze EMCV 3Cpro monoubiquitylation, but this activity does not influence the in vivo 3Cpro concentration.


Assuntos
Cisteína Endopeptidases/química , Cisteína Endopeptidases/metabolismo , Vírus da Encefalomiocardite/enzimologia , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Virais/química , Proteínas Virais/metabolismo , Proteases Virais 3C , Animais , Cisteína Endopeptidases/genética , Vírus da Encefalomiocardite/genética , Técnicas de Silenciamento de Genes , Interações Hospedeiro-Patógeno , Camundongos , Células NIH 3T3 , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/antagonistas & inibidores , Ubiquitina-Proteína Ligases/genética , Ubiquitinação , Proteínas Virais/genética
3.
Nat Immunol ; 16(12): 1215-27, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26479788

RESUMO

Enhancing the response to interferon could offer an immunological advantage to the host. In support of this concept, we used a modified form of the transcription factor STAT1 to achieve hyper-responsiveness to interferon without toxicity and markedly improve antiviral function in transgenic mice and transduced human cells. We found that the improvement depended on expression of a PARP9-DTX3L complex with distinct domains for interaction with STAT1 and for activity as an E3 ubiquitin ligase that acted on host histone H2BJ to promote interferon-stimulated gene expression and on viral 3C proteases to degrade these proteases via the immunoproteasome. Thus, PARP9-DTX3L acted on host and pathogen to achieve a double layer of immunity within a safe reserve in the interferon signaling pathway.


Assuntos
Cisteína Endopeptidases/metabolismo , Histonas/metabolismo , Poli(ADP-Ribose) Polimerases/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Virais/metabolismo , Proteases Virais 3C , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Vírus da Encefalomiocardite/fisiologia , Células HEK293 , Interações Hospedeiro-Patógeno , Humanos , Immunoblotting , Interferon beta/farmacologia , Interferon gama/farmacologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Confocal , Mutação , Poli(ADP-Ribose) Polimerases/genética , Ligação Proteica , Interferência de RNA , DNA Polimerase Dirigida por RNA , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismo , Transdução de Sinais , Transcriptoma/efeitos dos fármacos , Ubiquitina-Proteína Ligases/genética
4.
Virology ; 393(2): 311-8, 2009 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-19733381

RESUMO

RNA helicase-like receptors MDA-5 but not RIG-I has been shown to be essential for triggering innate immune responses against picornaviruses. However, virus-host co-evolution has selected for viruses capable of replicating despite host cells antiviral defences. In this report, we demonstrate that RIG-I is degraded during encephalomyocarditis virus (EMCV) infection. This effect is mediated by both the viral-encoded 3C protease and caspase proteinase. In addition, we show that RIG-I overexpression confers IFN-beta promoter activation during EMCV infection, in MDA-5 knockout (MDA-5(-/-)) mouse embryo fibroblasts. This induction is followed by a strong inhibition reflecting the ability of EMCV to disrupt RIG-I signalling. Taken together, our data strongly suggest that during evolution RIG-I has been involved for triggering innate immune response to picornavirus infections.


Assuntos
Infecções por Cardiovirus/imunologia , RNA Helicases DEAD-box/metabolismo , Vírus da Encefalomiocardite/imunologia , Imunidade Inata , Interferon beta/imunologia , Proteases Virais 3C , Animais , Infecções por Cardiovirus/virologia , Caspases/imunologia , Caspases/metabolismo , Cisteína Endopeptidases/imunologia , Cisteína Endopeptidases/metabolismo , Proteína DEAD-box 58 , RNA Helicases DEAD-box/imunologia , Vírus da Encefalomiocardite/metabolismo , Regulação da Expressão Gênica , Células HeLa , Humanos , Helicase IFIH1 Induzida por Interferon , Camundongos , Regiões Promotoras Genéticas , Proteínas Virais/imunologia , Proteínas Virais/metabolismo
5.
J Gen Virol ; 90(Pt 3): 536-545, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19218198

RESUMO

The interferon (IFN) system is a major effector of the innate immunity that allows time for the subsequent establishment of an adaptive immune response against a wide-range of pathogens. Their diverse biological actions are thought to be mediated by the products of specific but usually overlapping sets of cellular genes induced in the target cells. Ubiquitin ligase members of the tripartite motif (TRIM) protein family have emerged as IFN-induced proteins involved in both innate and adaptive immunity. In this report, we provide evidence that TRIM22 is a functional E3 ubiquitin ligase that is also ubiquitinated itself. We demonstrate that TRIM22 expression leads to a viral protection of HeLa cells against encephalomyocarditis virus infections. This effect is dependent upon its E3 ubiquitinating activity, since no antiviral effect was observed in cells expressing a TRIM22-deletion mutant defective in ubiquitinating activity. Consistent with this, TRIM22 interacts with the viral 3C protease (3C(PRO)) and mediates its ubiquitination. Altogether, our findings demonstrate that TRIM22 E3 ubiquitin ligase activity represents a new antiviral pathway induced by IFN against picornaviruses.


Assuntos
Antivirais/metabolismo , Cisteína Endopeptidases/metabolismo , Vírus da Encefalomiocardite/efeitos dos fármacos , Proteínas Repressoras/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Virais/metabolismo , Proteases Virais 3C , Antivirais/farmacologia , Linhagem Celular , Cisteína Endopeptidases/genética , Vírus da Encefalomiocardite/enzimologia , Vírus da Encefalomiocardite/genética , Células HeLa , Humanos , Antígenos de Histocompatibilidade Menor , Proteínas Repressoras/genética , Proteínas Repressoras/farmacologia , Proteínas com Motivo Tripartido , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/farmacologia , Proteínas Virais/genética
6.
Virology ; 360(2): 350-63, 2007 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-17150238

RESUMO

We have isolated stably transfected mouse embryonic fibroblast cell lines that inducibly express either the mature encephalomyocarditis virus (EMCV) or hepatitis A virus (HAV) 3C protease and have used these cells to demonstrate that both proteins are subject to degradation in vivo by the ubiquitin/26S proteasome system. The detection of 3C protease expression in these cells requires inducing conditions and the presence of one of several proteasome inhibitors. Both 3C proteases are incorporated into conjugates with ubiquitin in vivo. HAV 3C protease expression has deleterious effects on cell viability, as determined by observation and counting of cells cultured in the absence or presence of inducing conditions. The EMCV 3C protease was found to be preferentially localized to the nucleus of induced cells, while the HAV 3C protease remains in the cytoplasm. The absence of polyubiquitinated EMCV 3C protease conjugates in nuclear fraction preparations suggests that localization to the nucleus can protect this protein from ubiquitination.


Assuntos
Cisteína Endopeptidases/metabolismo , Vírus da Encefalomiocardite/enzimologia , Vírus da Hepatite A/enzimologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Virais/metabolismo , Proteases Virais 3C , Animais , Linhagem Celular , Núcleo Celular/química , Sobrevivência Celular , Cisteína Endopeptidases/biossíntese , Cisteína Endopeptidases/genética , Citoplasma/química , Fibroblastos/virologia , Humanos , Camundongos , Processamento de Proteína Pós-Traducional , Ubiquitina/metabolismo , Proteínas Virais/biossíntese , Proteínas Virais/genética
7.
Virology ; 309(2): 306-19, 2003 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-12758177

RESUMO

The hepatitis A virus 3C protease and 3D RNA polymerase are present in low concentrations in infected cells. The 3C protease was previously shown to be rapidly degraded by the ubiquitin/26S proteasome system and we present evidence here that the 3D polymerase is also subject to ubiquitination-mediated proteolysis. Our results show that the sequence (32)LGVKDDWLLV(41) in the 3C protease serves as a protein destruction signal recognized by the ubiquitin-protein ligase E3alpha and that the destruction signal for the RNA polymerase does not require the carboxyl-terminal 137 amino acids. Both the viral 3ABCD polyprotein and the 3CD diprotein were also found to be substrates for ubiquitin-mediated proteolysis. Attempts to determine if the 3C protease or the 3D polymerase destruction signals trigger the ubiquitination and degradation of these precursors yielded evidence suggesting, but not unequivocally proving, that the recognition of the 3D polymerase by the ubiquitin system is responsible.


Assuntos
Cisteína Endopeptidases/química , RNA Polimerases Dirigidas por DNA/metabolismo , Vírus da Hepatite A/enzimologia , Complexo de Endopeptidases do Proteassoma , Transdução de Sinais , Ubiquitina/metabolismo , Proteínas Virais/química , Proteases Virais 3C , Sequência de Aminoácidos , Animais , Cisteína Endopeptidases/genética , Cisteína Endopeptidases/metabolismo , Peptídeo Hidrolases/metabolismo , Poliproteínas/metabolismo , Precursores de Proteínas/metabolismo , Coelhos , Reticulócitos , Especificidade por Substrato , Proteínas Virais/genética , Proteínas Virais/metabolismo
8.
Nature ; 416(6882): 763-7, 2002 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-11961560

RESUMO

The 26S proteasome is the chief site of regulatory protein turnover in eukaryotic cells. It comprises one 20S catalytic complex (composed of four stacked rings of seven members) and two axially positioned 19S regulatory complexes (each containing about 18 subunits) that control substrate access to the catalytic chamber. In most cases, targeting to the 26S proteasome depends on tagging of the substrate with a specific type of polyubiquitin chain. Recognition of this signal is followed by substrate unfolding and translocation, which are presumably catalysed by one or more of six distinct AAA ATPases located in the base-a ring-like 19S subdomain that abuts the axial pore of the 20S complex and exhibits chaperone activity in vitro. Despite the importance of polyubiquitin chain recognition in proteasome function, the site of this signal's interaction with the 19S complex has not been identified previously. Here we use crosslinking to a reactive polyubiquitin chain to show that a specific ATPase subunit, S6' (also known as Rpt5), contacts the bound chain. The interaction of this signal with 26S proteasomes is modulated by ATP hydrolysis. Our results suggest that productive recognition of the proteolytic signal, as well as proteasome assembly and substrate unfolding, are ATP-dependent events.


Assuntos
Adenosina Trifosfatases/metabolismo , Peptídeo Hidrolases/química , Peptídeo Hidrolases/metabolismo , Poliubiquitina/metabolismo , Complexo de Endopeptidases do Proteassoma , Processamento de Proteína Pós-Traducional , Adenosina Trifosfatases/química , Trifosfato de Adenosina/metabolismo , Animais , Bovinos , Reagentes de Ligações Cruzadas , Espectroscopia de Ressonância de Spin Eletrônica , Hidrólise , Ligação Proteica , Subunidades Proteicas , Especificidade por Substrato
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...