Multiple truncated isoforms of MAVS prevent its spontaneous aggregation in antiviral innate immune signalling

Nat Commun. 2017 Jun 13:8:15676. doi: 10.1038/ncomms15676.

Abstract

In response to virus infection, RIG-I-like receptors (RLRs) sense virus RNA and induce MAVS to form prion-like aggregates to further propagate antiviral signalling. Although monomeric MAVS recombinant protein can assemble into prion-like filaments spontaneously in vitro, endogenous MAVS in cells is prevented from aggregation until viral infection. The mechanism preventing cellular MAVS from spontaneous aggregation is unclear. Here we show that multiple N-terminal truncated isoforms of MAVS are essential in preventing full-length MAVS from spontaneous aggregation through transmembrane domain-mediated homotypic interaction. Without these shorter isoforms, full-length MAVS is prone to spontaneous aggregation and Nix-mediated mitophagic degradation. In the absence of N-terminally truncated forms, blocking Nix-mediated mitophagy stabilizes full-length MAVS, which aggregates spontaneously and induces the subsequent expression of type I interferon and other proinflammatory cytokines. Our data thus uncover an important mechanism preventing spontaneous aggregation of endogenous MAVS to avoid accidental activation of antiviral innate immune signalling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / immunology*
  • Autophagy
  • Autophagy-Related Protein 5 / immunology
  • Beclin-1 / immunology
  • Flow Cytometry
  • Gene Deletion
  • Gene Knock-In Techniques
  • HEK293 Cells
  • Humans
  • Immunity, Innate*
  • Inflammation
  • Mitophagy
  • Protein Binding
  • Protein Domains
  • Protein Multimerization
  • RNA Virus Infections / immunology*
  • RNA, Small Interfering / metabolism
  • Signal Transduction

Substances

  • ATG5 protein, human
  • Adaptor Proteins, Signal Transducing
  • Autophagy-Related Protein 5
  • BECN1 protein, human
  • Beclin-1
  • MAVS protein, human
  • RNA, Small Interfering