RESUMO
The mediator of IRF3 activation (MITA, also named STING) is critical for immune responses to abnormal cytosolic DNA and has been considered an important drug target in the clinical therapy of tumors and autoimmune diseases. In the present study, we report that MITA undergoes DDOST-mediated N-glycosylation in the endoplasmic reticulum (ER) upon DNA viral infection. Selective mutation of DDOST-dependent N-glycosylated residues abolished MITA oligomerization and thereby its immune functions. Moreover, increasing the expression of Ddost in the mouse brain effectively strengthens the local immune response to herpes simplex virus-1 (HSV-1) and prolongs the survival time of mice with HSV encephalitis (HSE). Our findings reveal the dependence of N-glycosylation on MITA activation and provide a new perspective on the pathogenesis of HSE.
Assuntos
Doenças Autoimunes , Encefalite por Herpes Simples , Herpesvirus Humano 1 , Viroses , Animais , Camundongos , GlicosilaçãoRESUMO
TLR-mediated signaling pathways play critical roles in host defense against microbials. However, dysregulation of innate immune and inflammatory responses triggered by TLRs would result in harmful damage to the host. Using a Trim8 gene-knockout mouse model, we show that tripartite motif (TRIM) 8 negatively regulates TLR3- and TLR4-mediated innate immune and inflammatory responses. TRIM8 deficiency leads to increased polyinosinic-polycytidylic acid- and LPS-triggered induction of downstream anti-microbial genes including TNF, Il6, Rantes, and Ifnb, evaluated serum cytokine levels, and increased susceptibility of mice to polyinosinic-polycytidylic acid- and LPS-induced inflammatory death as well as Salmonella typhimurium infection-induced loss of body weight and septic shock. TRIM8 interacted with Toll/IL-1 receptor domain-containing adapter-inducing IFN-ß and mediated its K6- and K33-linked polyubiquitination, leading to disruption of the Toll/IL-1 receptor domain-containing adapter-inducing IFN-ß-TANK-binding kinase-1 association. Our findings uncover an additional mechanism on the termination of TLR3/4-mediated inflammatory and innate immune responses.
Assuntos
Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Proteínas de Transporte/metabolismo , Inflamação/imunologia , Proteínas do Tecido Nervoso/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Choque Séptico/imunologia , Animais , Proteínas de Transporte/genética , Citocinas/genética , Citocinas/metabolismo , Células HEK293 , Humanos , Imunidade Inata , Inflamação/microbiologia , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas do Tecido Nervoso/genética , Poli I-C/imunologia , Ligação Proteica , Transdução de Sinais , Receptor 3 Toll-Like/metabolismo , Receptor 4 Toll-Like/metabolismo , Ubiquitina-Proteína LigasesRESUMO
Toll-like receptors (TLRs) are pattern recognition receptors that sense a variety of pathogens, initiate innate immune responses, and direct adaptive immunity. All TLRs except TLR3 recruit the adaptor MyD88 to ultimately elicit inflammatory gene expression, whereas TLR3 and internalized TLR4 use TIR-domain-containing adaptor TRIF for the induction of type I interferon and inflammatory cytokines. Here, we identify the WD repeat and FYVE-domain-containing protein WDFY1 as a crucial adaptor protein in the TLR3/4 signaling pathway. Overexpression of WDFY1 potentiates TLR3- and TLR4-mediated activation of NF-κB, interferon regulatory factor 3 (IRF3), and production of type I interferons and inflammatory cytokines. WDFY1 depletion has the opposite effect. WDFY1 interacts with TLR3 and TLR4 and mediates the recruitment of TRIF to these receptors. Our findings suggest a crucial role for WDFY1 in bridging the TLR-TRIF interaction, which is necessary for TLR signaling.
Assuntos
Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Nucleares/genética , Receptor 3 Toll-Like/genética , Receptor 4 Toll-Like/genética , Fatores de Transcrição/genética , Proteínas Adaptadoras de Transdução de Sinal , Proteínas Adaptadoras de Transporte Vesicular/imunologia , Motivos de Aminoácidos , Citocinas/genética , Citocinas/imunologia , Regulação da Expressão Gênica , Células HEK293 , Humanos , Indutores de Interferon/farmacologia , Fator Regulador 3 de Interferon/genética , Fator Regulador 3 de Interferon/imunologia , Interferon Tipo I/genética , Interferon Tipo I/imunologia , Dados de Sequência Molecular , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/imunologia , NF-kappa B/genética , NF-kappa B/imunologia , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/imunologia , Plasmídeos/química , Plasmídeos/imunologia , Poli I-C/farmacologia , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Receptor 3 Toll-Like/imunologia , Receptor 4 Toll-Like/imunologia , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/imunologia , TransfecçãoRESUMO
Interferon-induced transmembrane protein 3 (IFITM3) is a restriction factor that can be induced by viral infection and interferons (IFNs). It inhibits the entry and replication of many viruses, which are independent of receptor usage but dependent on processes that occur in endosomes. In this study, we demonstrate that IFITM3 plays important roles in regulating the RNA-virus-triggered production of IFN-ß in a negative-feedback manner. Overexpression of IFITM3 inhibited Sendai virus-triggered induction of IFN-ß, whereas knockdown of IFITM3 had the opposite effect. We also showed that IFITM3 was constitutively associated with IRF3 and regulated the homeostasis of IRF3 by mediating the autophagic degradation of IRF3. These findings suggest a novel inhibitory function of IFITM3 on the RNA-virus-triggered production of type I IFNs and cellular antiviral responses.
Assuntos
Autofagossomos/metabolismo , Fator Regulador 3 de Interferon/imunologia , Interferon Tipo I/imunologia , Proteínas de Membrana/imunologia , Proteólise , Infecções por Vírus de RNA/imunologia , Vírus de RNA/imunologia , Proteínas de Ligação a RNA/imunologia , Células HEK293 , Células HeLa , Humanos , Fator Regulador 3 de Interferon/genética , Interferon Tipo I/genética , Proteínas de Membrana/genética , Infecções por Vírus de RNA/genética , Infecções por Vírus de RNA/patologia , Vírus de RNA/genética , Proteínas de Ligação a RNA/genéticaRESUMO
Mediator of IRF3 activation (MITA), also known as stimulator of interferon genes (STING), plays a vital role in the innate immune responses to cytosolic dsDNA. The trafficking of MITA from the ER to perinuclear vesicles is necessary for its activation of the downstream molecules, which lead to the production of interferons and pro-inflammatory cytokines. However, the exact mechanism of MITA activation remains elusive. Here, we report that transmembrane emp24 protein transport domain containing 2 (TMED2) potentiates DNA virus-induced MITA signaling. The suppression or deletion of TMED2 markedly impairs the production of type I IFNs upon HSV-1 infection. TMED2-deficient cells harbor greater HSV-1 load than the control cells. Mechanistically, TMED2 associates with MITA only upon viral stimulation, and this process potentiates MITA activation by reinforcing its dimerization and facilitating its trafficking. These findings suggest an essential role of TMED2 in cellular IFN responses to DNA viruses.