The RNA binding protein Quaking represses host interferon response by downregulating MAVS

Kuo Chieh Liao, Vanessa Chuo, W. Samuel Fagg, Shelton S. Bradrick, Julien Pompon, Mariano A. Garcia-Blanco

Research output: Contribution to journalArticle

Abstract

Quaking (QKI) is an RNA-binding protein (RBP) involved in multiple aspects of RNA metabolism and many biological processes. Despite a known immune function in regulating monocyte differentiation and inflammatory responses, the degree to which QKI regulates the host interferon (IFN) response remains poorly characterized. Here we show that QKI ablation enhances poly(I:C) and viral infection-induced IFNβ transcription. Characterization of IFN-related signalling cascades reveals that QKI knockout results in higher levels of IRF3 phosphorylation. Interestingly, complementation with QKI-5 isoform alone is sufficient to rescue this phenotype and reduce IRF3 phosphorylation. Further analysis shows that MAVS, but not RIG-I or MDA5, is robustly upregulated in the absence of QKI, suggesting that QKI downregulates MAVS and thus represses the host IFN response. As expected, MAVS depletion reduces IFNβ activation and knockout of MAVS in the QKI knockout cells completely abolishes IFNβ induction. Consistently, ectopic expression of RIG-I activates stronger IFNβ induction via MAVS-IRF3 pathway in the absence of QKI. Collectively, these findings demonstrate a novel role for QKI in negatively regulating host IFN response by reducing MAVS levels.

Original languageEnglish (US)
Pages (from-to)366-380
Number of pages15
JournalRNA Biology
Volume17
Issue number3
DOIs
StatePublished - Mar 3 2020

Keywords

  • IFN
  • IRF3
  • MAVS
  • QKI
  • viral infection

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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