Publication details
ADAR RNA editing in innate immune response phasing, in circadian clocks and in sleep
| Authors | |
|---|---|
| Year of publication | 2019 |
| Type | Article in Periodical |
| Magazine / Source | Biochimica et biophysica acta - Gene regulatory mechanisms |
| MU Faculty or unit | |
| Citation | |
| Web | Full Text |
| Doi | http://dx.doi.org/10.1016/j.bbagrm.2018.10.011 |
| Keywords | ADAR; RNA editing; dsRNA; microRNA; Epitranscriptome; Innate immunity; Circadian rhythm; Sleep |
| Description | Adenosine deaminases acting on RNA (ADARs) convert adenosine to inosine in dsRNA. ADAR editing in premRNAs recodes open reading frames and alters splicing, mRNA structure and interactions with miRNAs. Here, we review ADAR gene expression, splice forms, posttranslational modifications, subcellular localizations and functions of ADAR protein isoforms. ADAR1 edits cellular dsRNA to prevent aberrant activation of cytoplasmic antiviral dsRNA sensors; ADAR1 mutations lead to aberrant expression of interferon in Aicardi Goutieres syndrome (AGS), a human congenital encephalopathy. We review related studies on mouse Adarl mutant phenotypes, their rescues by preventing signaling from the antiviral RIG-I-like Sensors (RLRs), as well as Marl mechanisms in innate immune suppression and other roles of Adarl, including editing-independent effects. ADAR2, expressed primarily in CNS, edits glutamate receptor transcripts; regulation of ADAR2 activity in response to neuronal activity mediates homeostatic synaptic plasticity of vertebrate AMPA and kainite receptors. In Drosophila, synapses and synaptic proteins show dramatic decreases at night during sleep; Drosophila Adar, an orthologue of ADAR2, edits hundreds of mRNAs; the most conserved editing events occur in transcripts encoding synapse-associated proteins. Adar mutant flies exhibit locomotion defects associated with very increased sleep pressure resulting from a failure of homeostatic synaptic processes. A study on Adcir2 mutant mice identifies a new role in circadian rhythms, acting indirectly through miRNAs such as let-7 to modulate levels of let-7 target mRNAs; ADAR1 also regulates let-7 miRNA processing. Drosophila ADAR, an orthologue of vertebrate ADAR2, also regulates let-7 miRNA levels and Adar mutant flies have a circadian mutant phenotype. |
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