Critical role of an antiviral stress granule containing RIG-I and PKR in viral detection and innate immunity

PLoS One. 2012;7(8):e43031. doi: 10.1371/journal.pone.0043031. Epub 2012 Aug 13.

Abstract

Retinoic acid inducible gene I (RIG-I)-like receptors (RLRs) function as cytoplasmic sensors for viral RNA to initiate antiviral responses including type I interferon (IFN) production. It has been unclear how RIG-I encounters and senses viral RNA. To address this issue, we examined intracellular localization of RIG-I in response to viral infection using newly generated anti-RIG-I antibody. Immunohistochemical analysis revealed that RLRs localized in virus-induced granules containing stress granule (SG) markers together with viral RNA and antiviral proteins. Because of similarity in morphology and components, we termed these aggregates antiviral stress granules (avSGs). Influenza A virus (IAV) deficient in non-structural protein 1 (NS1) efficiently generated avSGs as well as IFN, however IAV encoding NS1 produced little. Inhibition of avSGs formation by removal of either the SG component or double-stranded RNA (dsRNA)-dependent protein kinase (PKR) resulted in diminished IFN production and concomitant enhancement of viral replication. Furthermore, we observed that transfection of dsRNA resulted in IFN production in an avSGs-dependent manner. These results strongly suggest that the avSG is the locus for non-self RNA sensing and the orchestration of multiple proteins is critical in the triggering of antiviral responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Viral / immunology
  • Chlorocebus aethiops
  • Cytoplasmic Granules / immunology*
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / immunology*
  • DEAD-box RNA Helicases / metabolism
  • Fibroblasts
  • HeLa Cells
  • Humans
  • Immunity, Innate / immunology*
  • Immunohistochemistry
  • Influenza A virus / immunology*
  • Interferon Type I / immunology
  • Mice
  • Mice, Knockout
  • Orthomyxoviridae Infections / immunology*
  • RNA, Viral / metabolism*
  • Vero Cells
  • eIF-2 Kinase / immunology*
  • eIF-2 Kinase / metabolism

Substances

  • Antibodies, Viral
  • Interferon Type I
  • RNA, Viral
  • eIF-2 Kinase
  • Ddx58 protein, mouse
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases

Grant support

The Ministry of Education, Culture, Sports, Science and Technology in Japan (Innovative Areas “RNA regulation” (No.20112009), Scientific Research “A”, and Research Activity Start-up) (http://www.mext.go.jp/english/), the Ministry of Health, Labour and Welfare of Japan (http://www.mhlw.go.jp/english/index.html), the PRESTO Japan Science and Technology Agency (http://www.jst.go.jp/kisoken/presto/index_e.html), the Uehara Memorial Foundation (http://www.ueharazaidan.com/), the Mochida Memorial Foundation for Medical and Pharmaceutical Research (http://www.mochida.co.jp/zaidan/), the Takaeda Science Foundation (http://www.takeda-sci.or.jp/index.html), the Naito Foundation (http://www.naito-f.or.jp/), and Nippon Boehringer Ingelheim (http://www.boehringer-ingelheim.co.jp/com/Home/index.jsp). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.