The RNA editing enzyme adenosine deaminase acting on RNA 1 (ADAR1) is essential for correct functioning of innate immune responses. The ADAR1p110 isoform is mainly nuclear and ADAR1p150, which is interferon (IFN) inducible, is predominately cytoplasmic. Using three different methods - co-immunoprecipitation (co-IP) of endogenous ADAR1, Strep-tag co-IP and BioID with individual ADAR1 isoforms - a comprehensive interactome was generated during both homeostasis and the IFN response. Both known and novel interactors as well as editing regulators were identified. Nuclear proteins were detected as stable interactors with both ADAR1 isoforms. In contrast, BioID identified distinct protein networks for each ADAR1 isoform, with nuclear components observed with ADAR1p110 and components of cytoplasmic cellular condensates with ADAR1p150. RNase A digestion distinguished between distal and proximal interactors, as did a double-stranded RNA (dsRNA)-binding mutant of ADAR1 which demonstrated the importance of dsRNA binding for ADAR1 interactions. IFN treatment did not affect the core ADAR1 interactomes but resulted in novel interactions, the majority of which are proximal interactions retained after RNase A treatment. Short treatment with high molecular weight poly(I:C) during the IFN response resulted in dsRNA-binding-dependent changes in the proximal protein network of ADAR1p110 and association of the ADAR1p150 proximal protein network with some components of antiviral stress granules.

• MeSH
• adenosindeaminasa * metabolismus   genetika   MeSH
• buněčné jádro * metabolismus   MeSH
• cytoplazma * metabolismus   MeSH
• dvouvláknová RNA metabolismus   genetika   MeSH
• editace RNA MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• interferony metabolismus   genetika   MeSH
• lidé MeSH
• mapy interakcí proteinů MeSH
• poly I-C farmakologie   MeSH
• protein - isoformy * metabolismus   genetika   MeSH
• proteiny vázající RNA * metabolismus   genetika   MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ADAR protein, human MeSH Prohlížeč
• adenosindeaminasa * MeSH
• dvouvláknová RNA MeSH
• interferony MeSH
• poly I-C MeSH
• protein - isoformy * MeSH
• proteiny vázající RNA * MeSH

The RNA editing enzyme ADAR2 is essential for the recoding of brain transcripts. Impaired ADAR2 editing leads to early-onset epilepsy and premature death in a mouse model. Here, we report bi-allelic variants in ADARB1, the gene encoding ADAR2, in four unrelated individuals with microcephaly, intellectual disability, and epilepsy. In one individual, a homozygous variant in one of the double-stranded RNA-binding domains (dsRBDs) was identified. In the others, variants were situated in or around the deaminase domain. To evaluate the effects of these variants on ADAR2 enzymatic activity, we performed in vitro assays with recombinant proteins in HEK293T cells and ex vivo assays with fibroblasts derived from one of the individuals. We demonstrate that these ADAR2 variants lead to reduced editing activity on a known ADAR2 substrate. We also demonstrate that one variant leads to changes in splicing of ADARB1 transcript isoforms. These findings reinforce the importance of RNA editing in brain development and introduce ADARB1 as a genetic etiology in individuals with intellectual disability, microcephaly, and epilepsy.

• Klíčová slova
• ADAR2, RNA editing, epilepsy, intellectual disability, microcephaly, migrating focal seizures,
• MeSH
• adenosindeaminasa genetika   MeSH
• alely MeSH
• alternativní sestřih genetika   MeSH
• dítě MeSH
• genetická predispozice k nemoci genetika   MeSH
• genetická variace genetika   MeSH
• HEK293 buňky MeSH
• lidé MeSH
• mentální retardace genetika   MeSH
• mikrocefalie genetika   MeSH
• předškolní dítě MeSH
• proteiny vázající RNA genetika   MeSH
• sestřih RNA genetika   MeSH
• záchvaty genetika   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• ADARB1 protein, human MeSH Prohlížeč
• adenosindeaminasa MeSH
• proteiny vázající RNA MeSH

The ADAR proteins deaminate adenosine to inosine in double-stranded RNA which is one of the most abundant modifications present in mammalian RNA. Inosine can have a profound effect on the RNAs that are edited, not only changing the base-pairing properties, but can also result in recoding, as inosine behaves as if it were guanosine. In mammals there are three ADAR proteins and two ADAR-related proteins (ADAD) expressed. All have a very similar modular structure; however, both their expression and biological function differ significantly. Only two of the ADAR proteins have enzymatic activity. However, both ADAR and ADAD proteins possess the ability to bind double-strand RNA. Mutations in ADARs have been associated with many diseases ranging from cancer, innate immunity to neurological disorders. Here, we will discuss in detail the domain structure of mammalian ADARs, the effects of RNA editing, and the role of ADARs in human diseases.

• Klíčová slova
• ADAR, Alu elements, RNA editing, cancer, deaminase domain, dsRBDs,
• MeSH
• adenosindeaminasa metabolismus   MeSH
• dvouvláknová RNA metabolismus   MeSH
• editace RNA genetika   MeSH
• lidé MeSH
• proteiny vázající RNA metabolismus   MeSH
• savci MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• adenosindeaminasa MeSH
• dvouvláknová RNA MeSH
• proteiny vázající RNA MeSH