HSCARG negatively regulates the cellular antiviral RIG-I like receptor signaling pathway by inhibiting TRAF3 ubiquitination via recruiting OTUB1

PLoS Pathog. 2014 Apr 24;10(4):e1004041. doi: 10.1371/journal.ppat.1004041. eCollection 2014 Apr.

Abstract

RIG-I like receptors (RLRs) recognize cytosolic viral RNA and initiate innate immunity; they increase the production of type I interferon (IFN) and the transcription of a series of antiviral genes to protect the host organism. Accurate regulation of the RLR pathway is important for avoiding tissue injury induced by excessive immune response. HSCARG is a newly reported negative regulator of NF-κB. Here we demonstrated that HSCARG participates in innate immunity. HSCARG inhibited the cellular antiviral response in an NF-κB independent manner, whereas deficiency of HSCARG had an opposite effect. After viral infection, HSCARG interacted with tumor necrosis receptor-associated factor 3 (TRAF3) and inhibited its ubiquitination by promoting the recruitment of OTUB1 to TRAF3. Knockout of HSCARG attenuated the de-ubiquitination of TRAF3 by OTUB1, and knockdown of OTUB1 abolished the effect of HSCARG. HSCARG also interacted with Ikappa-B kinase epsilon (IKKε) after viral infection and impaired the association between TRAF3 and IKKε, which further decreased the phosphorylation of IKKε and interferon response factor 3 (IRF3), thus suppressed the dimerization and nuclear translocation of IRF3. Moreover, knockdown of TRAF3 dampened the inhibitory effect of IFN-β transcription by HSCARG, suggesting that TRAF3 is necessary for HSCARG to down-regulate RLR pathway. This study demonstrated that HSCARG is a negative regulator that enables balanced antiviral innate immunity.

MeSH terms

  • Cell Line, Tumor
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / immunology
  • Cysteine Endopeptidases / metabolism*
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / immunology
  • DEAD-box RNA Helicases / metabolism*
  • Deubiquitinating Enzymes
  • Gene Knockdown Techniques
  • Humans
  • I-kappa B Kinase / genetics
  • I-kappa B Kinase / immunology
  • I-kappa B Kinase / metabolism
  • Immunity, Innate
  • RNA Virus Infections / genetics
  • RNA Virus Infections / immunology
  • RNA Virus Infections / metabolism
  • RNA Viruses / genetics
  • RNA Viruses / immunology
  • RNA Viruses / metabolism
  • RNA, Viral / genetics
  • RNA, Viral / immunology
  • RNA, Viral / metabolism*
  • Receptors, Immunologic
  • Signal Transduction / physiology*
  • TNF Receptor-Associated Factor 3 / genetics
  • TNF Receptor-Associated Factor 3 / immunology
  • TNF Receptor-Associated Factor 3 / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / immunology
  • Transcription Factors / metabolism*
  • Ubiquitination / physiology*

Substances

  • NMRAL1 protein, human
  • RNA, Viral
  • Receptors, Immunologic
  • TNF Receptor-Associated Factor 3
  • TRAF3 protein, human
  • Transcription Factors
  • I-kappa B Kinase
  • Deubiquitinating Enzymes
  • OTUB1 protein, human
  • Cysteine Endopeptidases
  • DDX58 protein, human
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases

Grant support

This work was supported by grants from the National Science Foundation of China 30930020 and 31170709, the National High Technology and Development Program of China 973 programs (No. 2010CB911800), Doctoral Fund of Ministry of Education of China (20130001130003) and the International Centre for Genetic Engineering and Biotechnology (ICGEB) (Project No. CRP/CHN09-01). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.