The RNA-Editing Enzyme ADAR1 Controls Innate Immune Responses to RNA

Niamh M. Mannion, Sam M. Greenwood, Robert Young, Sarah Cox, James Brindle, David Read, Christoffer Nellåker, Cornelia Vesely, Chris P. Ponting, Paul J. McLaughlin, Michael F. Jantsch, Julia Dorin, Ian R. Adams, A.D.J. Scadden, Marie Öhman, Liam P. Keegan, Mary A. O'Connell

Research output: Contribution to journalArticlepeer-review

Abstract

The ADAR RNA-editing enzymes deaminate adenosine bases to inosines in cellular RNAs. Aberrant interferon expression occurs in patients in whom ADAR1 mutations cause Aicardi-Goutières syndrome (AGS) or dystonia arising from striatal neurodegeneration. Adar1 mutant mouse embryos show aberrant interferon induction and die by embryonic day E12.5. We demonstrate that Adar1 embryonic lethality is rescued to live birth in Adar1; Mavs double mutants in which the antiviral interferon induction response to cytoplasmic double-stranded RNA (dsRNA) is prevented. Aberrant immune responses in Adar1 mutant mouse embryo fibroblasts are dramatically reduced by restoring the expression of editing-active cytoplasmic ADARs. We propose that inosine in cellular RNA inhibits antiviral inflammatory and interferon responses by altering RLR interactions. Transfecting dsRNA oligonucleotides containing inosine-uracil base pairs into Adar1 mutant mouse embryo fibroblasts reduces the aberrant innate immune response. ADAR1 mutations causing AGS affect the activity of the interferon-inducible cytoplasmic isoform more severely than the nuclear isoform.

Original languageEnglish
Pages (from-to)1482-1494
Number of pages13
JournalCell Reports
Volume9
Issue number4
Early online date13 Nov 2014
DOIs
Publication statusPublished - 20 Nov 2014

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