Targeting IRFs by ubiquitination: regulating antiviral responses

2008 ◽  
Vol 36 (3) ◽  
pp. 453-458 ◽  
Author(s):  
Rowan Higgs ◽  
Caroline A. Jefferies
Keyword(s):  
Transcription Factors ◽  
Viral Infection ◽  
Viral Proteins ◽  
Interferon Regulatory Factor ◽  
Type I ◽  
Regulatory Factor ◽  
Ubiquitin Pathway ◽  
Cellular Processes ◽  
Antiviral Responses ◽  
Type I Ifns

The IRF [IFN (interferon) regulatory factor] family of transcription factors control many cellular processes, including induction of key antiviral cytokines, type I IFNs, following viral infection. Recent studies have revealed several endogenous and viral proteins involved in ubiquitin-mediated regulation of IRF activity and thus having an impact on type I IFN signalling. Through the ubiquitin pathway, these proteins can manipulate the antiviral response either by initiating proteasomal degradation of the IRFs or, in contrast, by promoting activation of the IRFs.

An arms race: innate antiviral responses and counteracting viral strategies

2007 ◽  
Vol 35 (6) ◽  
pp. 1512-1514 ◽  
Author(s):  
M. Schröder ◽  
A.G. Bowie
Keyword(s):  
Nuclear Factor Κb ◽  
Signalling Pathways ◽  
Type I ◽  
Nuclear Factor ◽  
Regulatory Factor ◽  
Antiviral Responses ◽  
Type I Ifns ◽  
Activation Of Transcription ◽  
Molecular Patterns ◽  
Pro Inflammatory Cytokines

Viral recognition is mediated by different classes of PRRs (pattern-recognition receptors) among which the TLRs (Toll-like receptors) and the RLHs [RIG (retinoic-acid-inducible)-like helicases] play major roles. The detection of PAMPs (pathogen-associated molecular patterns) by these PRRs leads to the initiation of signalling pathways that ultimately result in the activation of transcription factors such as NF-κB (nuclear factor κB) and IRF-3 [IFN (interferon) regulatory factor-3] and IRF-7 and the induction of pro-inflammatory cytokines and type I IFNs. Viruses have evolved a fine-tuned mechanism to evade detection by the immune system or to interfere with the resulting signalling pathways. Here, we discuss viral evasion proteins that specifically interfere with TLR and/or RLH signalling.

scholarly journals Positive Regulation of Interferon Regulatory Factor 3 Activation by Herc5 via ISG15 Modification

2010 ◽  
Vol 30 (10) ◽  
pp. 2424-2436 ◽  
Author(s):  
He-Xin Shi ◽  
Kai Yang ◽  
Xing Liu ◽  
Xin-Yi Liu ◽  
Bo Wei ◽  
...  
Keyword(s):  
Sendai Virus ◽  
Specific Binding ◽  
Ectopic Expression ◽  
Interferon Regulatory Factor ◽  
Type I Interferons ◽  
Type I ◽  
Regulatory Factor ◽  
Interferon Regulatory Factor 3 ◽  
Antiviral Responses ◽  
Irf3 Activation

ABSTRACT Virus infection induces host antiviral responses, including induction of type I interferons. Transcription factor interferon regulatory factor 3 (IRF3) plays a pivotal role and is tightly regulated in this process. Here, we identify HERC5 (HECT domain and RLD 5) as a specific binding protein of IRF3 by immunoprecipitation. Ectopic expression or knockdown of HERC5 could, respectively, enhance or impair IRF3-mediated gene expression. Mechanistically, HERC5 catalyzes the conjugation of ubiquitin-like protein ISG15 onto IRF3 (Lys193, -360, and -366), thus attenuating the interaction between Pin1 and IRF3, resulting in sustained IRF3 activation. In contrast to results for wild-type IRF3, the mutant IRF3(K193,360,366R) interacts tightly with Pin1, is highly polyubiquitinated, and becomes less stable upon Sendai virus (SeV) infection. Consistently, host antiviral responses are obviously boosted or crippled in the presence or absence of HERC5, respectively. Collectively, this study characterizes HERC5 as a positive regulator of innate antiviral responses. It sustains IRF3 activation via a novel posttranslational modification, ISGylation.

scholarly journals USP22 promotes IRF3 nuclear translocation and antiviral responses by deubiquitinating the importin protein KPNA2

2020 ◽  
Vol 217 (5) ◽  
Author(s):  
Zeng Cai ◽  
Meng-Xin Zhang ◽  
Zhen Tang ◽  
Qiang Zhang ◽  
Jing Ye ◽  
...  
Keyword(s):  
Infectious Diseases ◽  
Viral Infection ◽  
Unknown Function ◽  
Nuclear Translocation ◽  
Therapeutic Strategies ◽  
Deubiquitinating Enzyme ◽  
Type I ◽  
Antiviral Responses ◽  
Type I Ifns ◽  
Increased Susceptibility

USP22 is a cytoplasmic and nuclear deubiquitinating enzyme, and the functions of cytoplasmic USP22 are unclear. Here, we discovered that cytoplasmic USP22 promoted nuclear translocation of IRF3 by deubiquitianting and stabilizing KPNA2 after viral infection. Viral infection induced USP22-IRF3 association in the cytoplasm in a KPNA2-depedent manner, and knockdown or knockout of USP22 or KPNA2 impaired IRF3 nuclear translocation and expression of downstream genes after viral infection. Consistently, Cre-ER Usp22fl/fl or Lyz2-Cre Usp22fl/fl mice produced decreased levels of type I IFNs after viral infection and exhibited increased susceptibility to lethal viral infection compared with the respective control littermates. Mechanistically, USP22 deubiquitinated and stabilized KPNA2 after viral infection to facilitate efficient nuclear translocation of IRF3. Reconstitution of KPNA2 into USP22 knockout cells restored virus-triggered nuclear translocation of IRF3 and cellular antiviral responses. These findings define a previously unknown function of cytoplasmic USP22 and establish a mechanistic link between USP22 and IRF3 nuclear translocation that expands potential therapeutic strategies for infectious diseases.

scholarly journals Identification of Feline Interferon Regulatory Factor 1 as an Efficient Antiviral Factor against the Replication of Feline Calicivirus and Other Feline Viruses

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yongxiang Liu ◽  
Xiaoxiao Liu ◽  
Hongtao Kang ◽  
Xiaoliang Hu ◽  
Jiasen Liu ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Viral Infections ◽  
Interferon Regulatory Factor ◽  
Feline Calicivirus ◽  
Type I ◽  
Norwalk Virus ◽  
Regulatory Factor ◽  
Feline Panleukopenia Virus ◽  
Protein Levels ◽  
Interferon Regulatory Factor 1

Interferons (IFNs) can inhibit most, if not all, viral infections by eliciting the transcription of hundreds of interferon-stimulated genes (ISGs). Feline calicivirus (FCV) is a highly contagious pathogen of cats and a surrogate for Norwalk virus. Interferon efficiently inhibits the replication of FCV, but the mechanism of the antiviral activity is poorly understood. Here, we evaluated the anti-FCV activity of ten ISGs, whose antiviral activities were previously reported. The results showed that interferon regulatory factor 1 (IRF1) can significantly inhibit the replication of FCV, whereas the other ISGs tested in this study failed. Further, we found that IRF1 was localized in the nucleus and efficiently activated IFN-β and the ISRE promoter. IRF1 can trigger the production of endogenous interferon and the expression of ISGs, suggesting that IRF1 can positively regulate IFN signalling. Importantly, the mRNA and protein levels of IRF1 were reduced upon FCV infection, which may be a new strategy for FCV to evade the innate immune system. Finally, the antiviral activity of IRF1 against feline panleukopenia virus, feline herpesvirus, and feline infectious peritonitis virus was demonstrated. These data indicate that feline IRF1 plays an important role in regulating the host type I IFN response and inhibiting feline viral infections.

scholarly journals USP1–UAF1 deubiquitinase complex stabilizes TBK1 and enhances antiviral responses

2017 ◽  
Vol 214 (12) ◽  
pp. 3553-3563 ◽  
Author(s):  
Zhongxia Yu ◽  
Hui Song ◽  
Mutian Jia ◽  
Jintao Zhang ◽  
Wenwen Wang ◽  
...  
Keyword(s):  
Viral Infection ◽  
Degradation Process ◽  
Viral Diseases ◽  
Immune Homeostasis ◽  
Regulatory Factor ◽  
Antiviral Responses ◽  
Innate Antiviral Immunity ◽  
Irf3 Activation

Optimal activation of TANK-binding kinase 1 (TBK1) is crucial for initiation of innate antiviral immunity and maintenance of immune homeostasis. Although several E3 ubiquitin ligases have been reported to regulate TBK1 activation by mediating its polyubiquitination, the functions of deubiquitinase on TBK1 activity remain largely unclear. Here, we identified a deubiquitinase complex, which is formed by ubiquitin specific peptidase 1 (USP1) and USP1-associated factor 1 (UAF1), as a viral infection–induced physiological enhancer of TBK1 expression. USP1–UAF1 complex enhanced TLR3/4 and RIG-I–induced IFN regulatory factor 3 (IRF3) activation and subsequent IFN-β secretion. Mechanistically, USP1 and UAF1 bound to TBK1, removed its K48-linked polyubiquitination, and then reversed the degradation process of TBK1. Furthermore, we found that ML323, a specific USP1–UAF1 inhibitor, attenuated IFN-β expression and enhanced viral replication both in vitro and in vivo. Therefore, our results outline a novel mechanism for the control of TBK1 activity and suggest USP1–UAF1 complex as a potential target for the prevention of viral diseases.

Structure and regulation of the human interferon regulatory factor 1 (IRF-1) and IRF-2 genes: implications for a gene network in the interferon system

1994 ◽  
Vol 14 (2) ◽  
pp. 1500-1509
Author(s):  
H Harada ◽  
E Takahashi ◽  
S Itoh ◽  
K Harada ◽  
T A Hori ◽  
...  
Keyword(s):  
Gene Network ◽  
Interferon Regulatory Factor ◽  
Chromosomal Mapping ◽  
Human Interferon ◽  
Type I ◽  
Regulatory Factor ◽  
Nf Kappa B ◽  
Interferon Regulatory Factor 1 ◽  
Two Factors ◽  
Dna Binding Factors

Interferon regulatory factor 1 (IRF-1) and IRF-2 are structurally similar DNA-binding factors which were originally identified as regulators of the type I interferon (IFN) system; the former functions as a transcriptional activator, and the latter represses IRF-1 function by competing for the same cis elements. More recent studies have revealed new roles of the two factors in the regulation of cell growth; IRF-1 and IRF-2 manifest antioncogenic and oncogenic activities, respectively. In this study, we determined the structures and chromosomal locations of the human IRF-1 and IRF-2 genes and further characterized the promoters of the respective genes. Comparison of exon-intron organization of the two genes revealed a common evolutionary structure, notably within the exons encoding the N-terminal portions of the two factors. We confirmed the chromosomal mapping of the human IRF-1 gene to 5q31.1 and newly assigned the IRF-2 gene to 4q35.1, using fluorescence in situ hybridization. The 5' regulatory regions of both genes contain highly GC-rich sequences and consensus binding sequences for several known transcription factors, including NF-kappa B. Interestingly, one IRF binding site was found within the IRF-2 promoter, and expression of the IRF-2 gene was affected by both transient and stable IRF-1 expression. In addition, one potential IFN-gamma-activated sequence was found within the IRF-1 promoter. Thus, these results may shed light on the complex gene network involved in regulation of the IFN system.

Sign in / Sign up

Export Citation Format

Share Document