ADAR1 Suppresses the Activation of Cytosolic RNA-Sensing Signaling Pathways to Protect the Liver from Ischemia/Reperfusion Injury

Sci Rep. 2016 Feb 1:6:20248. doi: 10.1038/srep20248.

Abstract

Excessive inflammation resulting from activation of the innate immune system significantly contributes to ischemia/reperfusion injury (IRI). Inflammatory reactions in both IRI and infections share the same signaling pathways evoked by danger/pathogen associated molecular pattern molecules. The cytosolic retinoid-inducible gene I(RIG-I)-like RNA receptor (RLR) RNA sensing pathway mediates type I IFN production during viral infection and the sensing of viral RNA is regulated by adenosine deaminase acting on RNA 1 (ADAR1). Using a model of liver IRI, we provide evidence that ADAR1 also regulates cytosolic RNA-sensing pathways in the setting of ischemic stress. Suppression of ADAR1 significantly enhanced inflammation and liver damage following IRI, which was accompanied by significant increases in type I IFN through cytosolic RNA-sensing pathways. In addition, knocking ADAR1 down in hepatocytes exaggerates inflammatory signaling to dsRNA or endotoxin and results in over production of type I IFN, which could be abolished by the interruption of RIG-I. Therefore, we identified a novel ADAR1-dependent protective contribution through which hepatocytes guard against aberrant cytosolic RLR-RNA-sensing pathway mediated inflammatory reaction in response to acute liver IR. ADAR1 protects against over activation of viral RNA-sensing pathways in non-infectious tissue stress.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Deaminase / genetics*
  • Adenosine Deaminase / metabolism
  • Animals
  • Apoptosis / genetics
  • Cytokines / biosynthesis
  • Cytosol / metabolism
  • Disease Models, Animal
  • Gene Expression
  • Hepatocytes / metabolism
  • Hepatocytes / pathology
  • Hypoxia / genetics
  • Hypoxia / metabolism
  • Liver / metabolism*
  • Liver / pathology
  • Mice
  • Mice, Knockout
  • Necrosis / genetics
  • Necrosis / metabolism
  • Necrosis / pathology
  • RNA / genetics*
  • RNA / immunology*
  • RNA-Binding Proteins / metabolism
  • Reperfusion Injury / etiology*
  • Reperfusion Injury / metabolism*
  • Reperfusion Injury / pathology
  • Signal Transduction*

Substances

  • Cytokines
  • RNA-Binding Proteins
  • RNA
  • ADAR1 protein, mouse
  • Adenosine Deaminase