Yang, W. et al. Modulation of microRNA processing and expression through RNA editing by ADAR deaminases. Nat. Struct. Mol. Biol. 13, 13-21

The Wistar Institute, 3601 Spruce Street, Philadelphia, Pennsylvania 19104, USA.
Nature Structural & Molecular Biology (Impact Factor: 13.31). 02/2006; 13(1):13-21. DOI: 10.1038/nsmb1041
Source: PubMed


Adenosine deaminases acting on RNA (ADARs) are involved in editing of adenosine residues to inosine in double-stranded RNA (dsRNA). Although this editing recodes and alters functions of several mammalian genes, its most common targets are noncoding repeat sequences, indicating the involvement of this editing system in currently unknown functions other than recoding of protein sequences. Here we show that specific adenosine residues of certain microRNA (miRNA) precursors are edited by ADAR1 and ADAR2. Editing of pri-miR-142, the precursor of miRNA-142, expressed in hematopoietic tissues, resulted in suppression of its processing by Drosha. The edited pri-miR-142 was degraded by Tudor-SN, a component of RISC and also a ribonuclease specific to inosine-containing dsRNAs. Consequently, mature miRNA-142 expression levels increased substantially in ADAR1 null or ADAR2 null mice. Our results demonstrate a new function of RNA editing in the control of miRNA biogenesis.


Available from: Kazuko Nishikura
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    • "The purpose of these modifications is context dependent; for example, adenylation is required for selective stabilization of miR-122 in mouse liver (Katoh et al. 2009), whereas in THP-1 cell line, adenylation reduces effectiveness of miR-26a, miR- 27a, and miR-122 (Burroughs et al. 2010). In vitro editing of pri-mir-142 in two positions remarkably reduced pre-mir- 142 synthesis (Yang et al. 2006). This indicates that miRNA editing is one of the mechanisms that increase the repertoire of miRNAs and their targets. "
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    ABSTRACT: MicroRNAs (miRNAs) are transcriptional and posttranscriptional regulators involved in nearly all known biological processes in distant eukaryotic clades. Their discovery and functional characterization have broadened our understanding of biological regulatory mechanisms in animals and plants. They show both evolutionary conserved and unique features across Metazoa. Here, we present the current status of the knowledge about the role of miRNA in development, growth, and physiology of teleost fishes, in comparison to other vertebrates. Infraclass Teleostei is the most abundant group among vertebrate lineage. Fish are an important component of aquatic ecosystems and human life, being the prolific source of animal proteins worldwide and a vertebrate model for biomedical research. We review miRNA biogenesis, regulation, modifications, and mechanisms of action. Specific sections are devoted to the role of miRNA in teleost development, organogenesis, tissue differentiation, growth, regeneration, reproduction, endocrine system, and responses to environmental stimuli. Each section discusses gaps in the current knowledge and pinpoints the future directions of research on miRNA in teleosts.
    Genome Biology and Evolution 07/2014; 6(8). DOI:10.1093/gbe/evu151 · 4.23 Impact Factor
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    • "Of interest, sequencing of cDNAs generated from microinjected pri-miRNA-142 failed to detect de novo RNA editing in vivo, leaving unprocessed pri-miRNA-142 stable in the egg. This finding is in contrast to the situation in tissue culture cells, where unprocessed pri-miRNA-142 was edited at multiple positions and then cleaved by Tudor-SN (Yang et al., 2006). The finding is even more surprising when one considers that RNA-editing activity was first identified in Xenopus oocytes and eggs (Rebagliati and Melton, 1987; Bass and Weintraub, 1988). "
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    ABSTRACT: MicroRNAs (miRNAs) are ∼21nt nucleotide long, single-stranded noncoding RNAs that regulate gene expression. Biogenesis of miRNAs is mediated by the two RNase III-like enzymes Drosha and Dicer. Here we study miRNA biogenesis during maturation of Xenopus oocytes to eggs using microinjection of pri-miRNAs. We show that processing of exogenous and endogenous pri-miRNAs is strongly enhanced upon maturation of oocytes to eggs. Overexpression of cloned Xenopus Drosha in oocytes, however, boosts pri-miRNA processing dramatically, indicating that Drosha is a rate-limiting factor in Xenopus oocytes. This developmental regulation of Drosha is controlled by poly-A length addition to the Drosha mRNA that boosts translation upon transition from oocytes to eggs. Processing of pri-miRNAs by Drosha and Dicer has been shown to be affected by adenosine to inosine deamination type RNA-editing. Using activated Xenopus eggs for microinjection experiments we demonstrate that RNA-editing can reduce pri-miRNA processing in vivo. This processing block is determined by the structural but not sequence changes introduced by RNA-editing.
    Molecular biology of the cell 05/2014; 25(13). DOI:10.1091/mbc.E13-07-0386 · 4.47 Impact Factor
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    • "In vitro editing assays were performed as described in (19) with the exception that purified Flag-tagged Drosophila ADAR was used in the assays. In vitro processing assays was performed as described in (27) with the exception that the reaction contained 15 µl of Flag-Drosha-Pasha beads immunoprecipitate, 6.4 mM MgCl2, 1U/µl of RNAse Inhibitor(Invitrogen) and the refolded labeled transcripts(0.5 × 105 cpm). "
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    ABSTRACT: Adenosine deaminases acting on RNAs (ADARs) convert adenosine residues to inosines in primary microRNA (pri-miRNA) transcripts to alter the structural conformation of these precursors and the subsequent functions of the encoded microRNAs (miRNAs). Here we show that RNA editing by Drosophila ADAR modulates the expression of three co-transcribed miRNAs encoded by the evolutionarily conserved let-7-Complex (let-7-C) locus. For example, a single A-to-I change at the −6 residue of pri-miR-100, the first miRNA in this let-7-C polycistronic transcript, leads to enhanced miRNA processing by Drosha and consequently enhanced functional miR-100 both in vitro as well as in vivo. In contrast, other editing events, including one at the +43 residue of the pri-miR-125, destabilize the primary transcript and reduce the levels of all three encoded miRNAs. Consequently, loss of adar in vivo leads to reduced miR-100 but increased miR-125. In wild-type animals, the destabilizing editing events in pri-let-7-C increase during the larval-to-adult transition and are critical for the normal downregulation of all three miRNAs seen late in metamorphosis. These findings unravel a new regulatory role for ADAR and raise the possibility that ADAR mediates the differential expression characteristic of many polycistronic miRNA clusters.
    Nucleic Acids Research 02/2014; 42(8). DOI:10.1093/nar/gku145 · 9.11 Impact Factor
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