ADAR Proteins: Structure and Catalytic Mechanism

Goodman, Rena A.; Macbeth, Mark R.; Beal, Peter A.

doi:10.1007/82_2011_144

Cited by 52 publications

(60 citation statements)

References 108 publications

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“…dsRNA is the substrate of ADARs (31,33,58). IFN treatment induces ADAR1 p150 (38,79), and ADARs (33,35), including ADAR1 (herein), destabilize RNA secondary structures that otherwise accumulate to a sufficiently high concentration to trigger dsRNA-dependent innate responses.…”

Section: Discussionmentioning

confidence: 99%

“…ADARs requires double-stranded RNA binding domains (58,59) that are present in multiple copies, three in ADAR1 p110 and p150 proteins and two copies in ADAR2 (34). The doublestranded RNA binding domains bind dsRNAs greater than ϳ16 bp in length in a sequence-independent manner, including dsRNAs with secondary structure defects (13,55,60,61).…”

Section: A-to-i Editing Of Cellular Transcripts Occurs Within Regionsmentioning

confidence: 99%

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Editing of Cellular Self-RNAs by Adenosine Deaminase ADAR1 Suppresses Innate Immune Stress Responses

George

Ramaswami

et al. 2016

Journal of Biological Chemistry

125

105

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One mechanism by which cells respond to different forms of stress is the global reduction of protein synthesis (1). Phosphorylation of protein synthesis initiation factor eIF2␣ on serine 51 is recognized as a universal mechanism of translation suppression in response to cellular stress (1, 2). Four different protein kinases are activated in mammalian cells in response to different stresses, and they all catalyze Ser-51 phosphorylation of eIF2␣ as follows: protein kinase regulated by RNA (PKR) activated by double-stranded RNA; heme-regulated inhibitor kinase activated by hemin deficiency and oxidative stress; general control non-derepressible kinase 2 (GCN2) activated by amino acid deficiency; and PKR-like endoplasmic reticulum kinase activated by protein misfolding and endoplasmic reticulum stress (2, 3). The global inhibition of translation in cultured cells mediated by eIF2␣ phosphorylation is linked to the formation of stress granules (SG), 2 cytoplasmic aggregates of stalled 40S ribosomal subunit-containing translation initiation complexes, translation initiation factors, and RNA-binding proteins, including Ras GTPase-activating protein-Src homology 3 domain binding protein 1 G3BP1 (4). Stress granule formation is one hallmark of virus infection, serving as an index of innate immune responses, and is PKR-dependent for a variety of viruses (5-8).A cornerstone of innate antiviral immunity is the interferon (IFN) system (9, 10). IFNs act through the transcriptional induction of IFN-stimulated genes that encode products responsible for the biological activities of IFNs, including the ability of IFNs to inhibit virus multiplication and enhance apoptosis (11-13). Among the IFN-stimulated gene products is the PKR kinase induced by IFN through canonical JAK-STAT signaling (14 -16). PKR is activated by binding dsRNA that mediates PKR dimerization and autophosphorylation; activated PKR catalyzes the phosphorylation of eIF2␣ (17)(18)(19)(20). In the case of several viruses, PKR displays antiviral and proapoptotic activities (12,21,22). Exemplified by measles virus, PKR sufficiency and kinase activation correlate with reduced virus growth (23, 24), enhanced induction of IFN␤ (25,26), increased SG responses (7), and increased cytotoxicity and apoptosis (27,28). The central importance of PKR furthermore is illustrated both by the large number of viruses that encode gene products that antagonize PKR activation and function, and by the effects of genetic disruption of the Pkr gene (12,13,29).Similar to PKR, ADAR1 (adenosine deaminase acting on RNA1) is an IFN-inducible dsRNA-binding protein with enzyme activity (30, 31). However, unlike PKR, ADAR1 uses dsRNA as a substrate (32). ADAR1 catalyzes the C6 deamination of adenosine (A) in dsRNA structures to generate inosine (I), a process known as A-to-I editing (33,34) samuel@lifesci.ucsb.edu.2 The abbreviations used are: SG, stress granule; ADAR1, adenosine deaminase acting on RNA1; MEF, mouse embryo fibroblast; mmPCR-seq, microfluidics-based multiplex PCR and deep sequencing;...

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Section: Discussionmentioning

confidence: 99%

Section: A-to-i Editing Of Cellular Transcripts Occurs Within Regionsmentioning

confidence: 99%

Editing of Cellular Self-RNAs by Adenosine Deaminase ADAR1 Suppresses Innate Immune Stress Responses

George

Ramaswami

et al. 2016

Journal of Biological Chemistry

125

105

View full text Add to dashboard Cite

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“…The ADAR and ADAR-like protein family members contain several common modular domains that are important for function (18,19). Most strikingly, the human ADAR and ADAR-like proteins contain at least one dsRNA binding domain (dsRBD), which are evolutionarily conserved among dsRNA-binding proteins (dsRBPs) and confer the ability to interact with dsRNA substrates (20).…”

Section: Edited By Charles E Samuelmentioning

confidence: 99%

Adenosine Deaminase That Acts on RNA 3 (ADAR3) Binding to Glutamate Receptor Subunit B Pre-mRNA Inhibits RNA Editing in Glioblastoma

Oakes¹,

Anderson

Cohen-Gadol

et al. 2017

Journal of Biological Chemistry

149

115

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Edited by Charles E. SamuelRNA editing is a cellular process that precisely alters nucleotide sequences, thus regulating gene expression and generating protein diversity. Over 60% of human transcripts undergo adenosine to inosine RNA editing, and editing is required for normal development and proper neuronal function of animals. Editing of one adenosine in the transcript encoding the glutamate receptor subunit B, glutamate receptor ionotropic AMPA 2 (GRIA2), modifies a codon, replacing the genomically encoded glutamine (Q) with arginine (R); thus this editing site is referred to as the Q/R site. Editing at the Q/R site of GRIA2 is essential, and reduced editing of GRIA2 transcripts has been observed in patients suffering from glioblastoma. In glioblastoma, incorporation of unedited GRIA2 subunits leads to a calcium-permeable glutamate receptor, which can promote cell migration and tumor invasion. In this study, we identify adenosine deaminase that acts on RNA 3 (ADAR3) as an important regulator of Q/R site editing, investigate its mode of action, and detect elevated ADAR3 expression in glioblastoma tumors compared with adjacent brain tissue. Overexpression of ADAR3 in astrocyte and astrocytoma cell lines inhibits RNA editing at the Q/R site of GRIA2. Furthermore, the double-stranded RNA binding domains of ADAR3 are required for repression of RNA editing. As the Q/R site of GRIA2 is specifically edited by ADAR2, we suggest that ADAR3 directly competes with ADAR2 for binding to GRIA2 transcript, inhibiting RNA editing, as evidenced by the direct binding of ADAR3 to the GRIA2 pre-mRNA. Finally, we provide evidence that both ADAR2 and ADAR3 expression contributes to the relative level of GRIA2 editing in tumors from patients suffering from glioblastoma.Adenosine deaminases that act on RNA (ADARs) 2 catalyze the hydrolytic deamination of adenosine residues within double-stranded RNA (dsRNA) structures that form by base pairing of nearby complementary sequences (1-3). This RNA editing event creates a non-canonical nucleoside, inosine, which base pairs similarly to guanosine (4). RNA editing affects gene expression through modification of codons to create novel protein isoforms (5). Furthermore, editing can alter microRNA and siRNA binding sites, splice acceptor or splice donor sites, or RNA structure and stability (6 -9). A majority of the targets of RNA editing are found in the nervous system, and RNA editing is critical for maintaining proper neuronal function (10). Furthermore, transcripts encoding proteins involved in neurotransmission are often targets of RNA editing, which alters the protein amino acid sequence and physiological function of these ion channels and receptors (11,12).In mammals, three ADAR proteins, ADAR1, ADAR2, and ADAR3, and two ADAR-like proteins, ADAD1 and ADAD2, have been identified (13-17). The ADAR and ADAR-like protein family members contain several common modular domains that are important for function (18,19). Most strikingly, the human ADAR and ADAR-like proteins contain at least one ds...

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“…Only later, it was demonstrated that this activity was a consequence of the A-to-I editing in dsRNAs (Bass and Weintraub 1988). Inosine is interpreted as guanosine by several cellular mechanisms, such as splicing, translation and reverse transcription (Bass et al 1997(Bass et al , 2002(Bass et al , 2002Goodman et al 2012;Nishikura 2016). As a consequence, A-to-I editing can potentially change the meaning of a specific codon, alter the splicing process, impair the microRNA processing and function, and affect several other aspects of RNA metabolism (Mannion et al 2015;Nishikura 2016;Chen and Carmichael 2012;Wang et al 2013;Ivanov et al 2015;Hogg et al 2011;Rueter et al 1999;Chen et al 2008b;Prasanth et al 2005;Capshew et al 2012;Vesely et al 2012Vesely et al , 2014.…”

Section: Aid/apobec Familymentioning

confidence: 99%

Post-transcriptional regulation of LINE-1 retrotransposition by AID/APOBEC and ADAR deaminases

et al. 2018

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Long interspersed element-1 (LINE-1 or L1) retrotransposons represent the only functional family of autonomous transposable elements in humans and formed 17% of our genome. Even though most of the human L1 sequences are inactive, a limited number of copies per individual retain the ability to mobilize by a process termed retrotransposition. The ongoing L1 retrotransposition may result in insertional mutagenesis that could lead to negative consequences such as genetic disease and cancer. For this reason, cells have evolved several mechanisms of defense to restrict L1 activity. Among them, a critical role for cellular deaminases [activation-induced deaminase (AID)/apolipoprotein B mRNA-editing catalytic polypeptide-like (APOBEC) and adenosine deaminases that act on RNA (ADAR) enzymes] has emerged. The majority of the AID/ APOBEC family of proteins are responsible for the deamination of cytosine to uracil (C-to-U editing) within DNA and RNA targets. The ADARs convert adenosine bases to inosines (A-to-I editing) within doublestranded RNA (dsRNA) targets. This review will discuss the current understanding of the regulation of LINE-1 retrotransposition mediated by these enzymes.

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ADAR Proteins: Structure and Catalytic Mechanism

Cited by 52 publications

References 108 publications

Editing of Cellular Self-RNAs by Adenosine Deaminase ADAR1 Suppresses Innate Immune Stress Responses

Editing of Cellular Self-RNAs by Adenosine Deaminase ADAR1 Suppresses Innate Immune Stress Responses

Adenosine Deaminase That Acts on RNA 3 (ADAR3) Binding to Glutamate Receptor Subunit B Pre-mRNA Inhibits RNA Editing in Glioblastoma

Post-transcriptional regulation of LINE-1 retrotransposition by AID/APOBEC and ADAR deaminases

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