PACT is required for MDA5-mediated immunoresponses triggered by Cardiovirus infection via interaction with LGP2

Biochem Biophys Res Commun. 2017 Dec 9;494(1-2):227-233. doi: 10.1016/j.bbrc.2017.10.048. Epub 2017 Oct 12.

Abstract

Laboratory of genetics and physiology 2 (LGP2) and melanoma differentiation-associated gene 5 (MDA5) cooperatively detect viral RNA in the cytoplasm of Cardiovirus-infected cells and activate innate immune responses. Here, we evaluated whether the double-stranded RNA-binding protein PACT plays a role in this anti-viral response to further elucidate the mechanism. Immunoprecipitation experiments demonstrated that PACT interacts with LGP2 and that this interaction is enhanced by encephalomyocarditis virus (EMCV) infection. In vitro interaction analyses using purified recombinant proteins confirmed that the single-stranded Theiler's murine encephalitis virus genome enhanced the interaction between LGP2 and PACT. Small interfering RNA knockdown experiments further indicated that PACT is required for Cardiovirus-triggered interferon responses. To support this functional interaction with LGP2, overexpressed PACT was shown to enhance EMCV-triggered interferon promoter activity only when LGP2 and MDA5 were co-expressed but not when MDA5 is expressed alone. Together, our findings indicate a possible role of PACT in regulating the Cardiovirus-triggered immune responses mediated by MDA5 and LGP2, which opens the door to novel therapeutic strategies in interferon-related autoimmune diseases and cancer.

Keywords: Cardiovirus; LGP2; MDA5; PACT; Picornavirus; RIG-I-like receptors; Type-I interferon.

MeSH terms

  • Animals
  • Cardiovirus Infections / genetics
  • Cardiovirus Infections / immunology*
  • Cardiovirus Infections / virology
  • Cell Line
  • Chlorocebus aethiops
  • DEAD-box RNA Helicases / antagonists & inhibitors
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / immunology
  • Encephalomyocarditis virus* / genetics
  • Encephalomyocarditis virus* / immunology
  • Gene Knockdown Techniques
  • HEK293 Cells
  • Host-Pathogen Interactions / genetics
  • Host-Pathogen Interactions / immunology
  • Humans
  • Immunity, Innate / genetics
  • Interferon-Induced Helicase, IFIH1 / genetics
  • Interferon-Induced Helicase, IFIH1 / immunology*
  • Interferon-beta / genetics
  • Mice
  • Promoter Regions, Genetic
  • RNA Helicases / genetics
  • RNA Helicases / immunology*
  • RNA, Small Interfering / genetics
  • RNA, Viral / genetics
  • RNA, Viral / immunology
  • RNA-Binding Proteins / antagonists & inhibitors
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / immunology*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Ribonuclease III / antagonists & inhibitors
  • Ribonuclease III / genetics
  • Ribonuclease III / immunology
  • Vero Cells

Substances

  • Prkra protein, mouse
  • RNA, Small Interfering
  • RNA, Viral
  • RNA-Binding Proteins
  • Recombinant Proteins
  • Interferon-beta
  • Dhx58 protein, mouse
  • Dicer1 protein, mouse
  • Ribonuclease III
  • Ifih1 protein, mouse
  • DEAD-box RNA Helicases
  • Interferon-Induced Helicase, IFIH1
  • RNA Helicases