ADAR1 Zα domain P195A mutation activates the MDA5-dependent RNA-sensing signaling pathway in brain without decreasing overall RNA editing

Guo, Xinfeng; Liu, Silvia; Yi, Sheng; Zenati, Mazen S.; Billiar, Timothy R.; Herbert, Alan; Wang, Qingde

doi:10.1016/j.celrep.2023.112733

Cited by 9 publications

(7 citation statements)

References 56 publications

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“…Adenosine deaminase acting on RNA 1 (ADAR1) is an A-to-I editase which regulates the innate immune response by preventing activation of dsRNA sensors. , The longer isoform of ADAR1 contains an N-terminal Zα domain, which has been shown to play an important role in ADAR1’s function. ,, Our finding that inosylation of the r(CpG) 6 construct increased its Z-form adoption rate to a comparable level as that of the r(CpG) 3 was striking. Based on this result, we speculate that the A-to-I editing activity of ADAR1 could promote Z-RNA adoption in ADAR1’s substrates which could in turn facilitate Zα binding and further A-to-I editing, helping to alleviate the loss of A-to-I editing activity observed on shorter dsRNA segments .…”

Section: Discussionmentioning

confidence: 84%

Z-Form Adoption of Nucleic Acid is a Multi-Step Process Which Proceeds through a Melted Intermediate

Nichols,

Krall,

Henen

et al. 2023

J. Am. Chem. Soc.

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The left-handed Z-conformation of nucleic acids can be adopted by both DNA and RNA when bound by Zα domains found within a variety of innate immune response proteins. Zα domains stabilize this higher-energy conformation by making specific interactions with the unique geometry of Z-DNA/Z-RNA. However, the mechanism by which a right-handed helix contorts to become left-handed in the presence of proteins, including the intermediate steps involved, is poorly understood. Through a combination of nuclear magnetic resonance (NMR) and other biophysical measurements, we have determined that in the absence of Zα, under low salt conditions at room temperature, d(CpG) and r(CpG) constructs show no observable evidence of transient Zconformations greater than 0.5% on either the intermediate or slow NMR time scales. At higher temperatures, we observed a transient unfolded intermediate. The ease of melting a nucleic acid duplex correlates with Z-form adoption rates in the presence of Zα. The largest contributing factor to the activation energies of Z-form adoption as calculated by Arrhenius plots is the ease of flipping the sugar pucker, as required for Z-DNA and Z-RNA. Together, these data validate the previously proposed "zipper model" for Z-form adoption in the presence of Zα. Overall, Z-conformations are more likely to be adopted by double-stranded DNA and RNA regions flanked by less stable regions and by RNAs experiencing torsional/mechanical stress.

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Section: Discussionmentioning

confidence: 84%

Z-Form Adoption of Nucleic Acid is a Multi-Step Process Which Proceeds through a Melted Intermediate

Nichols,

Krall,

Henen

et al. 2023

J. Am. Chem. Soc.

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“…However, homozygous mice carrying the P193A mutation alone exhibit a normal phenotype. 6,33,34 Since our analysis revealed that the R892H mutation alone can substantially disrupt catalysis of adenosine deamination by ADAR1, it is possible that the R892H mutation is the key change leading to disease for the P193A and R892H double mutant found in the AGS patient population. Additionally, a recent study by Jantsch et al has indicated that the specificity of the ADAR1 p150 isoform is predominantly influenced by cellular localization.…”

Section: ■ Discussionmentioning

confidence: 93%

“…17,18,31 There are a few reports in the field investigating the consequences of these mutations on RNA editing by ADAR1 in mammalian cell lines and animal models. 6,7,18,23,24 However, there are no published reports of the effects of these mutations on the biochemical properties of ADAR1 evaluated under well-defined solution conditions with purified proteins. Here we measured rates of adenosine deamination in two different RNA substrates and binding to 8-azaN RNAs for four different AGS-causing mutants of ADAR1.…”

Section: ■ Discussionmentioning

confidence: 99%

“…Recent studies have highlighted the regulatory roles of RNA editing by ADAR1 in preventing recognition of self RNA as viral or non-self. ,,, Given its role in immune regulation, loss of function mutations within the ADAR1 gene are associated with several immune disorders, including AGS. ,, There are a few reports in the field investigating the consequences of these mutations on RNA editing by ADAR1 in mammalian cell lines and animal models. ,,,, However, there are no published reports of the effects of these mutations on the biochemical properties of ADAR1 evaluated under well-defined solution conditions with purified proteins. Here we measured rates of adenosine deamination in two different RNA substrates and binding to 8-azaN RNAs for four different AGS-causing mutants of ADAR1.…”

Section: Discussionmentioning

confidence: 99%

“…ADAR1 exists as two distinct isoforms: the constitutively expressed short form, ADAR1 p110, and the interferon (IFN)-inducible form, p150, which consists of an additional Z-DNA/RNA (Zα) binding domain. The Zα domain of ADAR1 is important for substrate specificity and editing of Z-RNAs. − While both forms can shuttle between the nucleus and the cytoplasm, ADAR1 p110 is primarily localized in the nucleus, whereas p150 is predominantly found in the cytoplasm . Despite their high degree of similarity, ADAR1 and ADAR2 exhibit divergent substrate selectivity, which can be attributed to differences in their RNA binding domains and the distinct features of their catalytic domains .…”

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confidence: 99%

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Impact of Disease-Associated Mutations on the Deaminase Activity of ADAR1

Karki,

Campbell,

Mozumder

et al. 2024

Biochemistry

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The innate immune system relies on molecular sensors to detect distinctive molecular patterns, including viral doublestranded RNA (dsRNA), which triggers responses resulting in apoptosis and immune infiltration. Adenosine Deaminases Acting on RNA (ADARs) catalyze the deamination of adenosine (A) to inosine (I), serving as a mechanism to distinguish self from non-self RNA and prevent aberrant immune activation. Loss-of-function mutations in the ADAR1 gene are one cause of Aicardi Goutieres Syndrome (AGS), a severe autoimmune disorder in children. Although seven out of the eight AGS-associated mutations in ADAR1 occur within the catalytic domain of the ADAR1 protein, their specific effects on the catalysis of adenosine deamination remain poorly understood. In this study, we carried out a biochemical investigation of four AGS-causing mutations (G1007R, R892H, K999N, and Y1112F) in ADAR1 p110 and truncated variants. These studies included adenosine deamination rate measurements with two different RNA substrates derived from human transcripts known to be edited by ADAR1 p110 (glioma-associated oncogene homologue 1 (hGli1), 5-hydroxytryptamine receptor 2C (5-HT 2c R)). Our results indicate that AGS-associated mutations at two amino acid positions directly involved in stabilizing the baseflipped conformation of the ADAR-RNA complex (G1007R and R892H) had the most detrimental impact on catalysis. The K999N mutation, positioned near the RNA binding interface, altered catalysis contextually. Finally, the Y1112F mutation had small effects in each of the assays described here. These findings shed light on the differential effects of disease-associated mutations on adenosine deamination by ADAR1, thereby advancing our structural and functional understanding of ADAR1-mediated RNA editing.

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