51
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Chu D, Wei L. The chloroplast and mitochondrial C-to-U RNA editing in Arabidopsis thaliana shows signals of adaptation. PLANT DIRECT 2019; 3:e00169. [PMID: 31517178 PMCID: PMC6732656 DOI: 10.1002/pld3.169] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 08/18/2019] [Accepted: 08/23/2019] [Indexed: 05/20/2023]
Abstract
C-to-U RNA editing is the conversion from cytidine to uridine at RNA level. In plants, the genes undergo C-to-U RNA modification are mainly chloroplast and mitochondrial genes. Case studies have identified the roles of C-to-U editing in various biological processes, but the functional consequence of the majority of C-to-U editing events is still undiscovered. We retrieved the deep sequenced transcriptome data in roots and shoots of Arabidopsis thaliana and profiled their C-to-U RNA editomes and gene expression patterns. We investigated the editing level and conservation pattern of these C-to-U editing sites. The levels of nonsynonymous C-to-U editing events are higher than levels of synonymous events. The fraction of nonsynonymous editing sites is higher than neutral expectation. Highly edited cytidines are more conserved at DNA level, and the gene expression levels are correlated with C-to-U editing levels. Our results demonstrate that the global C-to-U editome is shaped by natural selection and that many nonsynonymous C-to-U editing events are adaptive. The editing mechanism might be positively selected and maintained and could have profound effects on the modified RNAs.
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Affiliation(s)
- Duan Chu
- College of Life SciencesBeijing Normal UniversityBeijingChina
| | - Lai Wei
- College of Life SciencesBeijing Normal UniversityBeijingChina
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52
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Shafiei H, Bakhtiarizadeh MR, Salehi A. Large‐scale potential
RNA
editing profiling in different adult chicken tissues. Anim Genet 2019; 50:460-474. [DOI: 10.1111/age.12818] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2019] [Indexed: 12/23/2022]
Affiliation(s)
- H. Shafiei
- Department of Animal and Poultry Science, College of Aburaihan University of Tehran Tehran33916-53775Iran
| | - M. R. Bakhtiarizadeh
- Department of Animal and Poultry Science, College of Aburaihan University of Tehran Tehran33916-53775Iran
| | - A. Salehi
- Department of Animal and Poultry Science, College of Aburaihan University of Tehran Tehran33916-53775Iran
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53
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Abstract
Modifications of RNA affect its function and stability. RNA editing is unique among these modifications because it not only alters the cellular fate of RNA molecules but also alters their sequence relative to the genome. The most common type of RNA editing is A-to-I editing by double-stranded RNA-specific adenosine deaminase (ADAR) enzymes. Recent transcriptomic studies have identified a number of 'recoding' sites at which A-to-I editing results in non-synonymous substitutions in protein-coding sequences. Many of these recoding sites are conserved within (but not usually across) lineages, are under positive selection and have functional and evolutionary importance. However, systematic mapping of the editome across the animal kingdom has revealed that most A-to-I editing sites are located within mobile elements in non-coding parts of the genome. Editing of these non-coding sites is thought to have a critical role in protecting against activation of innate immunity by self-transcripts. Both recoding and non-coding events have implications for genome evolution and, when deregulated, may lead to disease. Finally, ADARs are now being adapted for RNA engineering purposes.
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54
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Piontkivska H, Plonski NM, Miyamoto MM, Wayne ML. Explaining Pathogenicity of Congenital Zika and Guillain-Barré Syndromes: Does Dysregulation of RNA Editing Play a Role? Bioessays 2019; 41:e1800239. [PMID: 31106880 PMCID: PMC6699488 DOI: 10.1002/bies.201800239] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 03/28/2019] [Indexed: 12/11/2022]
Abstract
Previous studies of Zika virus (ZIKV) pathogenesis have focused primarily on virus-driven pathology and neurotoxicity, as well as host-related changes in cell proliferation, autophagy, immunity, and uterine function. It is now hypothesized that ZIKV pathogenesis arises instead as an (unintended) consequence of host innate immunity, specifically, as the side effect of an otherwise well-functioning machine. The hypothesis presented here suggests a new way of thinking about the role of host immune mechanisms in disease pathogenesis, focusing on dysregulation of post-transcriptional RNA editing as a candidate driver of a broad range of observed neurodevelopmental defects and neurodegenerative clinical symptoms in both infants and adults linked with ZIKV infections. The authors collect and synthesize existing evidence of ZIKV-mediated changes in the expression of adenosine deaminases acting on RNA (ADARs), known links between abnormal RNA editing and pathogenesis, as well as ideas for future research directions, including potential treatment strategies.
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Affiliation(s)
- Helen Piontkivska
- Department of Biological Sciences and University, Kent, OH
44242, USA
- School of Biomedical Sciences, Kent State University, Kent,
OH 44242, USA
| | - Noel-Marie Plonski
- School of Biomedical Sciences, Kent State University, Kent,
OH 44242, USA
| | | | - Marta L. Wayne
- Department of Biology, University of Florida, Gainesville,
FL 32611, USA
- Emerging Pathogens Institute, University of Florida,
Gainesville, FL 32611, USA
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55
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Li C, Zhang J. Stop-codon read-through arises largely from molecular errors and is generally nonadaptive. PLoS Genet 2019; 15:e1008141. [PMID: 31120886 PMCID: PMC6550407 DOI: 10.1371/journal.pgen.1008141] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/05/2019] [Accepted: 04/16/2019] [Indexed: 12/02/2022] Open
Abstract
Stop-codon read-through refers to the phenomenon that a ribosome goes past the stop codon and continues translating into the otherwise untranslated region (UTR) of a transcript. Recent ribosome-profiling experiments in eukaryotes uncovered widespread stop-codon read-through that also varies among tissues, prompting the adaptive hypothesis that stop-codon read-through is an important, regulated mechanism for generating proteome diversity. Here we propose and test a competing hypothesis that stop-codon read-through arises mostly from molecular errors and is largely nonadaptive. The error hypothesis makes distinct predictions about the probability of read-through, frequency of sequence motifs for read-through, and conservation of the read-through region, each of which is supported by genome-scale data from yeasts and fruit flies. Thus, except for the few cases with demonstrated functions, stop-codon read-through is generally nonadaptive. This finding, along with other molecular errors recently quantified, reveals a much less precise or orderly cellular life than is commonly thought.
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Affiliation(s)
- Chuan Li
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
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56
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Abstract
Although the neutral theory of molecular evolution was proposed to explain DNA and protein sequence evolution, in principle it could also explain phenotypic evolution. Nevertheless, overall, phenotypes should be less likely than genotypes to evolve neutrally. I propose that, when phenotypic traits are stratified according to a hierarchy of biological organization, the fraction of evolutionary changes in phenotype that are adaptive rises with the phenotypic level considered. Consistently, molecular traits are frequently found to evolve neutrally whereas a large, random set of organismal traits were recently reported to vary largely adaptively. Many more studies of unbiased samples of phenotypic traits are needed to test the general validity of this hypothesis.
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Affiliation(s)
- Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
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57
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Xu C, Park JK, Zhang J. Evidence that alternative transcriptional initiation is largely nonadaptive. PLoS Biol 2019; 17:e3000197. [PMID: 30883542 PMCID: PMC6438578 DOI: 10.1371/journal.pbio.3000197] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/28/2019] [Accepted: 03/12/2019] [Indexed: 12/22/2022] Open
Abstract
Alternative transcriptional initiation (ATI) refers to the frequent observation that one gene has multiple transcription start sites (TSSs). Although this phenomenon is thought to be adaptive, the specific advantage is rarely known. Here, we propose that each gene has one optimal TSS and that ATI arises primarily from imprecise transcriptional initiation that could be deleterious. This error hypothesis predicts that (i) the TSS diversity of a gene reduces with its expression level; (ii) the fractional use of the major TSS increases, but that of each minor TSS decreases, with the gene expression level; and (iii) cis-elements for major TSSs are selectively constrained, while those for minor TSSs are not. By contrast, the adaptive hypothesis does not make these predictions a priori. Our analysis of human and mouse transcriptomes confirms each of the three predictions. These and other findings strongly suggest that ATI predominantly results from molecular errors, requiring a major revision of our understanding of the precision and regulation of transcription. The transcription of a gene may start from one of several transcription start sites, a phenomenon known as alternative transcriptional initiation. Contrary to common belief, this study shows that variation of the transcription start site of a given gene is nonadaptive and is largely attributable to transcriptional initiation error that is typically deleterious. Multiple surveys of transcriptional initiation showed that mammalian genes typically have multiple transcription start sites such that transcription is initiated from any one of these sites. Many researchers believe that this phenomenon is adaptive because it allows production of multiple transcripts, from the same gene, that potentially vary in function or post-transcriptional regulation. Nevertheless, it is also possible that each gene has only one optimal transcription start site and that alternative transcriptional initiation arises primarily from molecular errors that are slightly deleterious. This error hypothesis makes a series of predictions about the amount of transcription start site diversity per gene, relative uses of the various start sites of a gene, among-tissue and across-species differences in start site usage, and the evolutionary conservation of cis-regulatory elements of various start sites, all of which are verified in our analyses of genome-wide transcription start site data from the human and mouse. These findings strongly suggest that alternative transcriptional initiation largely reflects molecular errors instead of molecular adaptations and require a rethink of the precision and regulation of transcription.
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Affiliation(s)
- Chuan Xu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Joong-Ki Park
- Division of EcoScience, Ewha Womans University, Seoul, Republic of Korea
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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58
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Abstract
C-to-U RNA editing enzymatically converts the base C to U in RNA molecules and could lead to nonsynonymous changes when occurring in coding regions. Hundreds to thousands of coding sites were recently found to be C-to-U edited or editable in humans, but the biological significance of this phenomenon is elusive. Here, we test the prevailing hypothesis that nonsynonymous editing is beneficial because it provides a means for tissue- or time-specific regulation of protein function that may be hard to accomplish by mutations due to pleiotropy. The adaptive hypothesis predicts that the fraction of sites edited and the median proportion of RNA molecules edited (i.e., editing level) are both higher for nonsynonymous than synonymous editing. However, our empirical observations are opposite to these predictions. Furthermore, the frequency of nonsynonymous editing, relative to that of synonymous editing, declines as genes become functionally more important or evolutionarily more constrained, and the nonsynonymous editing level at a site is negatively correlated with the evolutionary conservation of the site. Together, these findings refute the adaptive hypothesis; they instead indicate that the reported C-to-U coding RNA editing is mostly slightly deleterious or neutral, probably resulting from off-target activities of editing enzymes. Along with similar conclusions on the more prevalent A-to-I editing and m6A modification of coding RNAs, our study suggests that, at least in humans, most events of each type of posttranscriptional coding RNA modification likely manifest cellular errors rather than adaptations, demanding a paradigm shift in the research of posttranscriptional modification.
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Affiliation(s)
- Zhen Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
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59
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Bian Z, Ni Y, Xu JR, Liu H. A-to-I mRNA editing in fungi: occurrence, function, and evolution. Cell Mol Life Sci 2019; 76:329-340. [PMID: 30302531 PMCID: PMC11105437 DOI: 10.1007/s00018-018-2936-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 09/27/2018] [Accepted: 10/03/2018] [Indexed: 12/17/2022]
Abstract
A-to-I RNA editing is an important post-transcriptional modification that converts adenosine (A) to inosine (I) in RNA molecules via hydrolytic deamination. Although editing of mRNAs catalyzed by adenosine deaminases acting on RNA (ADARs) is an evolutionarily conserved mechanism in metazoans, organisms outside the animal kingdom lacking ADAR orthologs were thought to lack A-to-I mRNA editing. However, recent discoveries of genome-wide A-to-I mRNA editing during the sexual stage of the wheat scab fungus Fusarium graminearum, model filamentous fungus Neurospora crassa, Sordaria macrospora, and an early diverging filamentous ascomycete Pyronema confluens indicated that A-to-I mRNA editing is likely an evolutionarily conserved feature in filamentous ascomycetes. More importantly, A-to-I mRNA editing has been demonstrated to play crucial roles in different sexual developmental processes and display distinct tissue- or development-specific regulation. Contrary to that in animals, the majority of fungal RNA editing events are non-synonymous editing, which were shown to be generally advantageous and favored by positive selection. Many non-synonymous editing sites are conserved among different fungi and have potential functional and evolutionary importance. Here, we review the recent findings about the occurrence, regulation, function, and evolution of A-to-I mRNA editing in fungi.
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Affiliation(s)
- Zhuyun Bian
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Yajia Ni
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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60
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Hung LY, Chen YJ, Mai TL, Chen CY, Yang MY, Chiang TW, Wang YD, Chuang TJ. An Evolutionary Landscape of A-to-I RNA Editome across Metazoan Species. Genome Biol Evol 2018; 10:521-537. [PMID: 29294013 PMCID: PMC5800060 DOI: 10.1093/gbe/evx277] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2017] [Indexed: 12/12/2022] Open
Abstract
Adenosine-to-inosine (A-to-I) editing is widespread across the kingdom Metazoa. However, for the lack of comprehensive analysis in nonmodel animals, the evolutionary history of A-to-I editing remains largely unexplored. Here, we detect high-confidence editing sites using clustering and conservation strategies based on RNA sequencing data alone, without using single-nucleotide polymorphism information or genome sequencing data from the same sample. We thereby unveil the first evolutionary landscape of A-to-I editing maps across 20 metazoan species (from worm to human), providing unprecedented evidence on how the editing mechanism gradually expands its territory and increases its influence along the history of evolution. Our result revealed that highly clustered and conserved editing sites tended to have a higher editing level and a higher magnitude of the ADAR motif. The ratio of the frequencies of nonsynonymous editing to that of synonymous editing remarkably increased with increasing the conservation level of A-to-I editing. These results thus suggest potentially functional benefit of highly clustered and conserved editing sites. In addition, spatiotemporal dynamics analyses reveal a conserved enrichment of editing and ADAR expression in the central nervous system throughout more than 300 Myr of divergent evolution in complex animals and the comparability of editing patterns between invertebrates and between vertebrates during development. This study provides evolutionary and dynamic aspects of A-to-I editome across metazoan species, expanding this important but understudied class of nongenomically encoded events for comprehensive characterization.
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Affiliation(s)
- Li-Yuan Hung
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Yen-Ju Chen
- Genomics Research Center, Academia Sinica, Taipei, Taiwan.,Genome and Systems Biology Degree Program, Academia Sinica and National Taiwan University, Taipei, Taiwan
| | - Te-Lun Mai
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Chia-Ying Chen
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Min-Yu Yang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Tai-Wei Chiang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Yi-Da Wang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Trees-Juen Chuang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan.,Genome and Systems Biology Degree Program, Academia Sinica and National Taiwan University, Taipei, Taiwan
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61
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Affiliation(s)
- Ines Teichert
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universitaet Bochum, Germany
- * E-mail:
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62
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Xu C, Zhang J. Alternative Polyadenylation of Mammalian Transcripts Is Generally Deleterious, Not Adaptive. Cell Syst 2018; 6:734-742.e4. [PMID: 29886108 DOI: 10.1016/j.cels.2018.05.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/27/2018] [Accepted: 05/09/2018] [Indexed: 01/07/2023]
Abstract
Alternative polyadenylation (APA) produces from the same gene multiple mature RNAs with varying 3' ends. Although APA is commonly believed to generate beneficial functional diversity and be adaptive, we hypothesize that most genes have one optimal polyadenylation site and that APA is caused largely by deleterious polyadenylation errors. The error hypothesis, but not the adaptive hypothesis, predicts that, as the expression level of a gene increases, its polyadenylation diversity declines, relative use of the major (presumably optimal) polyadenylation site increases, and that of each minor (presumably nonoptimal) site decreases. It further predicts that the number of polyadenylation signals per gene is smaller than the random expectation and that polyadenylation signals for major but not minor sites are under purifying selection. All of these predictions are confirmed in mammals, suggesting that numerous defective RNAs are produced in normal cells, many phenotypic variations at the molecular level are nonadaptive, and cellular life is noisier than is appreciated.
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Affiliation(s)
- Chuan Xu
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Ecology and Evolutionary Biology, University of Michigan, 4018 Biological Science Building, 1105 North University Avenue, Ann Arbor, MI 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, 4018 Biological Science Building, 1105 North University Avenue, Ann Arbor, MI 48109, USA.
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63
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Pan S, Bruford MW, Wang Y, Lin Z, Gu Z, Hou X, Deng X, Dixon A, Graves JAM, Zhan X. Transcription-Associated Mutation Promotes RNA Complexity in Highly Expressed Genes-A Major New Source of Selectable Variation. Mol Biol Evol 2018; 35:1104-1119. [PMID: 29420738 PMCID: PMC5913671 DOI: 10.1093/molbev/msy017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Alternatively spliced transcript isoforms are thought to play a critical role for functional diversity. However, the mechanism generating the enormous diversity of spliced transcript isoforms remains unknown, and its biological significance remains unclear. We analyzed transcriptomes in saker falcons, chickens, and mice to show that alternative splicing occurs more frequently, yielding more isoforms, in highly expressed genes. We focused on hemoglobin in the falcon, the most abundantly expressed genes in blood, finding that alternative splicing produces 10-fold more isoforms than expected from the number of splice junctions in the genome. These isoforms were produced mainly by alternative use of de novo splice sites generated by transcription-associated mutation (TAM), not by the RNA editing mechanism normally invoked. We found that high expression of globin genes increases mutation frequencies during transcription, especially on nontranscribed DNA strands. After DNA replication, transcribed strands inherit these somatic mutations, creating de novo splice sites, and generating multiple distinct isoforms in the cell clone. Bisulfate sequencing revealed that DNA methylation may counteract this process by suppressing TAM, suggesting DNA methylation can spatially regulate RNA complexity. RNA profiling showed that falcons living on the high Qinghai-Tibetan Plateau possess greater global gene expression levels and higher diversity of mean to high abundance isoforms (reads per kilobases per million mapped reads ≥18) than their low-altitude counterparts, and we speculate that this may enhance their oxygen transport capacity under low-oxygen environments. Thus, TAM-induced RNA diversity may be physiologically significant, providing an alternative strategy in lifestyle evolution.
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Affiliation(s)
- Shengkai Pan
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,Cardiff University-Institute of Zoology Joint Laboratory for Biocomplexity Research, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Michael W Bruford
- Cardiff University-Institute of Zoology Joint Laboratory for Biocomplexity Research, Beijing, China.,Organisms and Environment Division, School of Biosciences and Sustainable Place Institute, Cardiff University, Cardiff, United Kingdom
| | - Yusong Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Zhenzhen Lin
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,Cardiff University-Institute of Zoology Joint Laboratory for Biocomplexity Research, Beijing, China
| | - Zhongru Gu
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,Cardiff University-Institute of Zoology Joint Laboratory for Biocomplexity Research, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xian Hou
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xuemei Deng
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding, and Reproduction of the Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Andrew Dixon
- Cardiff University-Institute of Zoology Joint Laboratory for Biocomplexity Research, Beijing, China.,Emirates Falconers' Club, Abu Dhabi, UAE
| | | | - Xiangjiang Zhan
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,Cardiff University-Institute of Zoology Joint Laboratory for Biocomplexity Research, Beijing, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China
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64
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Porath HT, Schaffer AA, Kaniewska P, Alon S, Eisenberg E, Rosenthal J, Levanon EY, Levy O. A-to-I RNA Editing in the Earliest-Diverging Eumetazoan Phyla. Mol Biol Evol 2018; 34:1890-1901. [PMID: 28453786 PMCID: PMC5850803 DOI: 10.1093/molbev/msx125] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The highly conserved ADAR enzymes, found in all multicellular metazoans, catalyze the editing of mRNA transcripts by the deamination of adenosines to inosines. This type of editing has two general outcomes: site specific editing, which frequently leads to recoding, and clustered editing, which is usually found in transcribed genomic repeats. Here, for the first time, we looked for both editing of isolated sites and clustered, non-specific sites in a basal metazoan, the coral Acropora millepora during spawning event, in order to reveal its editing pattern. We found that the coral editome resembles the mammalian one: it contains more than 500,000 sites, virtually all of which are clustered in non-coding regions that are enriched for predicted dsRNA structures. RNA editing levels were increased during spawning and increased further still in newly released gametes. This may suggest that editing plays a role in introducing variability in coral gametes.
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Affiliation(s)
- Hagit T Porath
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Amos A Schaffer
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Paulina Kaniewska
- Global Change Institute, The University of Queensland, St Lucia, Australia
| | - Shahar Alon
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Joshua Rosenthal
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, The Marine Biological Laboratory, Woods Hole, MA
| | - Erez Y Levanon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Oren Levy
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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65
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Duan Y, Dou S, Zhang H, Wu C, Wu M, Lu J. Linkage of A-to-I RNA Editing in Metazoans and the Impact on Genome Evolution. Mol Biol Evol 2018; 35:132-148. [PMID: 29048557 PMCID: PMC5850729 DOI: 10.1093/molbev/msx274] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The adenosine-to-inosine (A-to-I) RNA editomes have been systematically characterized in various metazoan species, and many editing sites were found in clusters. However, it remains unclear whether the clustered editing sites tend to be linked in the same RNA molecules or not. By adopting a method originally designed to detect linkage disequilibrium of DNA mutations, we examined the editomes of ten metazoan species and detected extensive linkage of editing in Drosophila and cephalopods. The prevalent linkages of editing in these two clades, many of which are conserved between closely related species and might be associated with the adaptive proteomic recoding, are maintained by natural selection at the cost of genome evolution. Nevertheless, in worms and humans, we only detected modest proportions of linked editing events, the majority of which were not conserved. Furthermore, the linkage of editing in coding regions of worms and humans might be overall deleterious, which drives the evolution of DNA sites to escape promiscuous editing. Altogether, our results suggest that the linkage landscape of A-to-I editing has evolved during metazoan evolution. This present study also suggests that linkage of editing should be considered in elucidating the functional consequences of RNA editing.
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Affiliation(s)
- Yuange Duan
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Shengqian Dou
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Hong Zhang
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Changcheng Wu
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Mingming Wu
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Jian Lu
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
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66
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Liu Z, Zhang J. Most m6A RNA Modifications in Protein-Coding Regions Are Evolutionarily Unconserved and Likely Nonfunctional. Mol Biol Evol 2017; 35:666-675. [PMID: 29228327 DOI: 10.1093/molbev/msx320] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Methylation of the adenosine base at the nitrogen-6 position (m6A) is the most prevalent internal posttranscriptional modification of mRNAs in many eukaryotes. Despite the rapid progress in the transcriptome-wide mapping of m6As, identification of proteins responsible for writing, reading, and erasing m6As, and elucidation of m6A functions in splicing, RNA stability, translation, and other processes, it is unknown whether most observed m6A modifications are functional. To address this question, we respectively analyze the evolutionary conservation of yeast and human m6As in protein-coding regions. Relative to comparable unmethylated As, m6As are overall no more conserved in yeasts and only slightly more conserved in mammals. Furthermore, yeast m6As and comparable unmethylated As have no significant difference in single nucleotide polymorphism (SNP) density or SNP site frequency spectrum. The same is true in human. The methylation status of a gene, not necessarily the specific sites methylated in the gene, is subject to purifying selection for no more than ∼20% of m6A-modified genes. These observations suggest that most m6A modifications in protein-coding regions are nonfunctional and nonadaptive, probably resulting from off-target activities of m6A methyltransferases. In addition, our reanalysis invalidates the recent claim of positive selection for newly acquired m6A modifications in human evolution. Regarding the small number of evolutionarily conserved m6As, evidence suggests that a large proportion of them are likely functional; they should be prioritized in future functional characterizations of m6As. Together, these findings have important implications for understanding the biological significance of m6A and other posttranscriptional modifications.
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Affiliation(s)
- Zhen Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
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67
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Sloan DB. Nuclear and mitochondrial RNA editing systems have opposite effects on protein diversity. Biol Lett 2017; 13:rsbl.2017.0314. [PMID: 28855414 DOI: 10.1098/rsbl.2017.0314] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 08/07/2017] [Indexed: 12/11/2022] Open
Abstract
RNA editing can yield protein products that differ from those directly encoded by genomic DNA. This process is pervasive in the mitochondria of many eukaryotes, where it predominantly results in the restoration of ancestral protein sequences. Nuclear mRNAs in metazoans also undergo editing (adenosine-to-inosine or 'A-to-I' substitutions), and most of these edits appear to be nonadaptive 'misfirings' of adenosine deaminases. However, recent analysis of cephalopod transcriptomes found that many editing sites are shared by anciently divergent lineages within this group, suggesting they play some adaptive role. Recent discoveries have also revealed that some fungi have an independently evolved A-to-I editing mechanism, resulting in extensive recoding of their nuclear mRNAs. Here, phylogenetic comparisons were used to determine whether RNA editing generally restores ancestral protein sequences or creates derived variants. Unlike in mitochondrial systems, RNA editing in metazoan and fungal nuclear transcripts overwhelmingly leads to novel sequences not found in inferred ancestral proteins. Even for the subset of RNA editing sites shared by deeply divergent cephalopod lineages, the primary effect of nuclear editing is an increase-not a decrease-in protein divergence. These findings suggest fundamental differences in the forces responsible for the evolution of RNA editing in nuclear versus mitochondrial systems.
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Affiliation(s)
- Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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68
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Abstract
Adenosine-to-inosine (A-to-I) RNA editing is an important post-transcriptional modification that affects the information encoded from DNA to RNA to protein. RNA editing can generate a multitude of transcript isoforms and can potentially be used to optimize protein function in response to varying conditions. In light of this and the fact that millions of editing sites have been identified in many different species, it is interesting to examine the extent to which these sites have evolved to be functionally important. In this review, we discuss results pertaining to the evolution of RNA editing, specifically in humans, cephalopods, and Drosophila. We focus on how comparative genomics approaches have aided in the identification of sites that are likely to be advantageous. The use of RNA editing as a mechanism to adapt to varying environmental conditions will also be reviewed.
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Affiliation(s)
- Arielle L. Yablonovitch
- Stanford University, Department of Genetics, Stanford, California, United States of America
- Stanford University, Biophysics Program, Stanford, California, United States of America
| | - Patricia Deng
- Stanford University, Department of Genetics, Stanford, California, United States of America
| | - Dionna Jacobson
- Stanford University, Department of Genetics, Stanford, California, United States of America
| | - Jin Billy Li
- Stanford University, Department of Genetics, Stanford, California, United States of America
- * E-mail:
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69
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A-to-I RNA editing is developmentally regulated and generally adaptive for sexual reproduction in Neurospora crassa. Proc Natl Acad Sci U S A 2017; 114:E7756-E7765. [PMID: 28847945 DOI: 10.1073/pnas.1702591114] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although fungi lack adenosine deaminase acting on RNA (ADAR) enzymes, adenosine to inosine (A-to-I) RNA editing was reported recently in Fusarium graminearum during sexual reproduction. In this study, we profiled the A-to-I editing landscape and characterized its functional and adaptive properties in the model filamentous fungus Neurospora crassa A total of 40,677 A-to-I editing sites were identified, and approximately half of them displayed stage-specific editing or editing levels at different sexual stages. RNA-sequencing analysis with the Δstc-1 and Δsad-1 mutants confirmed A-to-I editing occurred before ascus development but became more prevalent during ascosporogenesis. Besides fungal-specific sequence and secondary structure preference, 63.5% of A-to-I editing sites were in the coding regions and 81.3% of them resulted in nonsynonymous recoding, resulting in a significant increase in the proteome complexity. Many genes involved in RNA silencing, DNA methylation, and histone modifications had extensive recoding, including sad-1, sms-3, qde-1, and dim-2. Fifty pseudogenes harbor premature stop codons that require A-to-I editing to encode full-length proteins. Unlike in humans, nonsynonymous editing events in N. crassa are generally beneficial and favored by positive selection. Almost half of the nonsynonymous editing sites in N. crassa are conserved and edited in Neurospora tetrasperma Furthermore, hundreds of them are conserved in F. graminearum and had higher editing levels. Two unknown genes with editing sites conserved between Neurospora and Fusarium were experimentally shown to be important for ascosporogenesis. This study comprehensively analyzed A-to-I editing in N. crassa and showed that RNA editing is stage-specific and generally adaptive, and may be functionally related to repeat induced point mutation and meiotic silencing by unpaired DNA.
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70
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Dynamic hyper-editing underlies temperature adaptation in Drosophila. PLoS Genet 2017; 13:e1006931. [PMID: 28746393 PMCID: PMC5550009 DOI: 10.1371/journal.pgen.1006931] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 08/09/2017] [Accepted: 07/18/2017] [Indexed: 02/04/2023] Open
Abstract
In Drosophila, A-to-I editing is prevalent in the brain, and mutations in the editing enzyme ADAR correlate with specific behavioral defects. Here we demonstrate a role for ADAR in behavioral temperature adaptation in Drosophila. Although there is a higher level of editing at lower temperatures, at 29°C more sites are edited. These sites are less evolutionarily conserved, more disperse, less likely to be involved in secondary structures, and more likely to be located in exons. Interestingly, hypomorph mutants for ADAR display a weaker transcriptional response to temperature changes than wild-type flies and a highly abnormal behavioral response upon temperature increase. In sum, our data shows that ADAR is essential for proper temperature adaptation, a key behavior trait that is essential for survival of flies in the wild. Moreover, our results suggest a more general role of ADAR in regulating RNA secondary structures in vivo. In this work, we study one of the most abundant, yet poorly characterized genomic phenomena that has the potential to change the basic biological dogma–RNA editing, which creates transcriptome diversity by transforming adenosine into guanosine in RNA sequences. Such alteration, which is performed by ADAR family of deaminases, does not damage the original genomic version, and can be revised when circumstances change. Our analysis demonstrates that ADAR plays an important role in temperature adaptation by sensing and acting globally on RNA secondary structure. We suggest that ADAR has evolved to be highly efficient at cold temperatures, where RNA secondary structure is more prevalent. On the contrary, at high temperatures, where the secondary structure is more labile, ADAR may have negative effects, as it increases the chance of substitution in exonic sequences. Moreover, we observed behavioral defects in the ADAR hypomorphs at high temperatures.
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71
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Liscovitch-Brauer N, Alon S, Porath HT, Elstein B, Unger R, Ziv T, Admon A, Levanon EY, Rosenthal JJC, Eisenberg E. Trade-off between Transcriptome Plasticity and Genome Evolution in Cephalopods. Cell 2017; 169:191-202.e11. [PMID: 28388405 DOI: 10.1016/j.cell.2017.03.025] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/02/2017] [Accepted: 03/16/2017] [Indexed: 12/29/2022]
Abstract
RNA editing, a post-transcriptional process, allows the diversification of proteomes beyond the genomic blueprint; however it is infrequently used among animals for this purpose. Recent reports suggesting increased levels of RNA editing in squids thus raise the question of the nature and effects of these events. We here show that RNA editing is particularly common in behaviorally sophisticated coleoid cephalopods, with tens of thousands of evolutionarily conserved sites. Editing is enriched in the nervous system, affecting molecules pertinent for excitability and neuronal morphology. The genomic sequence flanking editing sites is highly conserved, suggesting that the process confers a selective advantage. Due to the large number of sites, the surrounding conservation greatly reduces the number of mutations and genomic polymorphisms in protein-coding regions. This trade-off between genome evolution and transcriptome plasticity highlights the importance of RNA recoding as a strategy for diversifying proteins, particularly those associated with neural function. PAPERCLIP.
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Affiliation(s)
- Noa Liscovitch-Brauer
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shahar Alon
- Media Lab and McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hagit T Porath
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Boaz Elstein
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ron Unger
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Tamar Ziv
- Smoler Proteomics Center and Faculty of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Arie Admon
- Smoler Proteomics Center and Faculty of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Erez Y Levanon
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Joshua J C Rosenthal
- Eugene Bell Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA; Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan 00901, Puerto Rico.
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel.
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72
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Lualdi S, Del Zotto G, Zegarra-Moran O, Pedemonte N, Corsolini F, Bruschi M, Tomati V, Amico G, Candiano G, Dardis A, Cooper DN, Filocamo M. In vitro recapitulation of the site-specific editing (to wild-type) of mutant IDS mRNA transcripts, and the characterization of IDS protein translated from the edited mRNAs. Hum Mutat 2017; 38:849-862. [PMID: 28477385 DOI: 10.1002/humu.23243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 04/05/2017] [Accepted: 04/22/2017] [Indexed: 11/06/2022]
Abstract
The transfer of genomic information into the primary RNA sequence can be altered by RNA editing. We have previously shown that genomic variants can be RNA-edited to wild-type. The presence of distinct "edited" iduronate 2-sulfatase (IDS) mRNA transcripts ex vivo evidenced the correction of a nonsense and frameshift variant, respectively, in three unrelated Hunter syndrome patients. This phenomenon was confirmed in various patient samples by a variety of techniques, and was quantified by single-nucleotide primer extension. Western blotting also confirmed the presence of IDS protein similar in size to the wild-type. Since preliminary experimental evidence suggested that the "corrected" IDS proteins produced by the patients were similar in molecular weight and net charge to their wild-type counterparts, an in vitro system employing different cell types was established to recapitulate the site-specific editing of IDS RNA (uridine to cytidine conversion and uridine deletion), and to confirm the findings previously observed ex vivo in the three patients. In addition, confocal microscopy and flow cytometry analyses demonstrated the expression and lysosomal localization in HEK293 cells of GFP-labeled proteins translated from edited IDS mRNAs. Confocal high-content analysis of the two patients' cells expressing wild-type or mutated IDS confirmed lysosomal localization and showed no accumulation in the Golgi or early endosomes.
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Affiliation(s)
- Susanna Lualdi
- UOSD Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto Giannina Gaslini, Genova, Italy
| | | | | | | | - Fabio Corsolini
- UOSD Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto Giannina Gaslini, Genova, Italy
| | - Maurizio Bruschi
- Laboratory on Physiopathology of Uremia, Istituto Giannina Gaslini, Genova, Italy
| | - Valeria Tomati
- UOC Genetica Medica, Istituto Giannina Gaslini, Genova, Italy
| | - Giulia Amico
- UOSD Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto Giannina Gaslini, Genova, Italy
| | - Giovanni Candiano
- Laboratory on Physiopathology of Uremia, Istituto Giannina Gaslini, Genova, Italy
| | - Andrea Dardis
- Regional Coordinator Centre for Rare Diseases, University Hospital Santa Maria della Misericordia, Udine, Italy
| | - David N Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Mirella Filocamo
- UOSD Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, Istituto Giannina Gaslini, Genova, Italy
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73
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Duan Y, Dou S, Luo S, Zhang H, Lu J. Adaptation of A-to-I RNA editing in Drosophila. PLoS Genet 2017; 13:e1006648. [PMID: 28282384 PMCID: PMC5365144 DOI: 10.1371/journal.pgen.1006648] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 03/24/2017] [Accepted: 02/21/2017] [Indexed: 01/14/2023] Open
Abstract
Adenosine-to-inosine (A-to-I) editing is hypothesized to facilitate adaptive evolution by expanding proteomic diversity through an epigenetic approach. However, it is challenging to provide evidences to support this hypothesis at the whole editome level. In this study, we systematically characterized 2,114 A-to-I RNA editing sites in female and male brains of D. melanogaster, and nearly half of these sites had events evolutionarily conserved across Drosophila species. We detected strong signatures of positive selection on the nonsynonymous editing sites in Drosophila brains, and the beneficial editing sites were significantly enriched in genes related to chemical and electrical neurotransmission. The signal of adaptation was even more pronounced for the editing sites located in X chromosome or for those commonly observed across Drosophila species. We identified a set of gene candidates (termed "PSEB" genes) that had nonsynonymous editing events favored by natural selection. We presented evidence that editing preferentially increased mutation sequence space of evolutionarily conserved genes, which supported the adaptive evolution hypothesis of editing. We found prevalent nonsynonymous editing sites that were favored by natural selection in female and male adults from five strains of D. melanogaster. We showed that temperature played a more important role than gender effect in shaping the editing levels, although the effect of temperature is relatively weaker compared to that of species effect. We also explored the relevant factors that shape the selective patterns of the global editomes. Altogether we demonstrated that abundant nonsynonymous editing sites in Drosophila brains were adaptive and maintained by natural selection during evolution. Our results shed new light on the evolutionary principles and functional consequences of RNA editing.
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Affiliation(s)
- Yuange Duan
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences & Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Shengqian Dou
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences & Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Shiqi Luo
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences & Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Hong Zhang
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences & Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Jian Lu
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences & Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
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74
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Zhang R, Deng P, Jacobson D, Li JB. Evolutionary analysis reveals regulatory and functional landscape of coding and non-coding RNA editing. PLoS Genet 2017; 13:e1006563. [PMID: 28166241 PMCID: PMC5319793 DOI: 10.1371/journal.pgen.1006563] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 02/21/2017] [Accepted: 01/03/2017] [Indexed: 11/18/2022] Open
Abstract
Adenosine-to-inosine RNA editing diversifies the transcriptome and promotes functional diversity, particularly in the brain. A plethora of editing sites has been recently identified; however, how they are selected and regulated and which are functionally important are largely unknown. Here we show the cis-regulation and stepwise selection of RNA editing during Drosophila evolution and pinpoint a large number of functional editing sites. We found that the establishment of editing and variation in editing levels across Drosophila species are largely explained and predicted by cis-regulatory elements. Furthermore, editing events that arose early in the species tree tend to be more highly edited in clusters and enriched in slowly-evolved neuronal genes, thus suggesting that the main role of RNA editing is for fine-tuning neurological functions. While nonsynonymous editing events have been long recognized as playing a functional role, in addition to nonsynonymous editing sites, a large fraction of 3’UTR editing sites is evolutionarily constrained, highly edited, and thus likely functional. We find that these 3’UTR editing events can alter mRNA stability and affect miRNA binding and thus highlight the functional roles of noncoding RNA editing. Our work, through evolutionary analyses of RNA editing in Drosophila, uncovers novel insights of RNA editing regulation as well as its functions in both coding and non-coding regions. Many important modifications are made to RNA to fine-tune genomic information. One type, Adenosine-to-Inosine (A-to-I) RNA editing, changes certain adenosines to inosines and is essential for the neurological well-being of many animals. Although RNA editing occurs at thousands of sites across the genomes of various animals, the functions of nearly all editing events–particularly those in non-coding regions–have not been studied, and what determines whether particular adenosines across the genome are edited has not been fully explored. Here, using the Drosophila genus as model organisms, we analyze the evolution of A-to-I RNA editing to identify a large fraction of both coding and non-coding editing events that are under evolutionary constraint and therefore likely functionally important. We find that non-coding editing events in the 3’UTRs of genes could affect miRNA binding and are associated with a decrease in gene expression levels.
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Affiliation(s)
- Rui Zhang
- Department of Genetics, Stanford University, Stanford, California, United States of America
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, P. R. China
- * E-mail: (JBL); (RZ)
| | - Patricia Deng
- Department of Genetics, Stanford University, Stanford, California, United States of America
| | - Dionna Jacobson
- Department of Genetics, Stanford University, Stanford, California, United States of America
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, California, United States of America
- * E-mail: (JBL); (RZ)
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75
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Piontkivska H, Matos LF, Paul S, Scharfenberg B, Farmerie WG, Miyamoto MM, Wayne ML. Role of Host-Driven Mutagenesis in Determining Genome Evolution of Sigma Virus (DMelSV; Rhabdoviridae) in Drosophila melanogaster. Genome Biol Evol 2016; 8:2952-2963. [PMID: 27614234 PMCID: PMC5630973 DOI: 10.1093/gbe/evw212] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Sigma virus (DMelSV) is ubiquitous in natural populations of Drosophila melanogaster. Host-mediated, selective RNA editing of adenosines to inosines (ADAR) may contribute to control of viral infection by preventing transcripts from being transported into the cytoplasm or being translated accurately; or by increasing the viral genomic mutation rate. Previous PCR-based studies showed that ADAR mutations occur in DMelSV at low frequency. Here we use SOLiDTM deep sequencing of flies from a single host population from Athens, GA, USA to comprehensively evaluate patterns of sequence variation in DMelSV with respect to ADAR. GA dinucleotides, which are weak targets of ADAR, are strongly overrepresented in the positive strand of the virus, consistent with selection to generate ADAR resistance on this complement of the transient, double-stranded RNA intermediate in replication and transcription. Potential ADAR sites in a worldwide sample of viruses are more likely to be “resistant” if the sites do not vary among samples. Either variable sites are less constrained and hence are subject to weaker selection than conserved sites, or the variation is driven by ADAR. We also find evidence of mutations segregating within hosts, hereafter referred to as hypervariable sites. Some of these sites were variable only in one or two flies (i.e., rare); others were shared by four or even all five of the flies (i.e., common). Rare and common hypervariable sites were indistinguishable with respect to susceptibility to ADAR; however, polymorphism in rare sites were more likely to be consistent with the action of ADAR than in common ones, again suggesting that ADAR is deleterious to the virus. Thus, in DMelSV, host mutagenesis is constraining viral evolution both within and between hosts.
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Affiliation(s)
- Helen Piontkivska
- Department of Biological Sciences and School of Biomedical Sciences, Kent State University, Kent, OH
| | - Luis F Matos
- Department of Entomology & Nematology, University of Florida, Gainesville, FL Department of Biology, Eastern Washington University, Cheney, WA
| | - Sinu Paul
- Department of Biological Sciences and School of Biomedical Sciences, Kent State University, Kent, OH Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA
| | - Brian Scharfenberg
- Department of Biological Sciences and School of Biomedical Sciences, Kent State University, Kent, OH Ohio University Heritage College of Osteopathic Medicine, Athens, OH
| | - William G Farmerie
- Interdisciplinary Center for Biotechnology Research University of Florida, Gainesville, FL
| | | | - Marta L Wayne
- Department of Biology, University of Florida, Gainesville, FL Emerging Pathogens Institute University of Florida, Gainesville, FL
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76
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The Landscape of A-to-I RNA Editome Is Shaped by Both Positive and Purifying Selection. PLoS Genet 2016; 12:e1006191. [PMID: 27467689 PMCID: PMC4965139 DOI: 10.1371/journal.pgen.1006191] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 06/22/2016] [Indexed: 12/18/2022] Open
Abstract
The hydrolytic deamination of adenosine to inosine (A-to-I editing) in precursor mRNA induces variable gene products at the post-transcription level. How and to what extent A-to-I RNA editing diversifies transcriptome is not fully characterized in the evolution, and very little is known about the selective constraints that drive the evolution of RNA editing events. Here we present a study on A-to-I RNA editing, by generating a global profile of A-to-I editing for a phylogeny of seven Drosophila species, a model system spanning an evolutionary timeframe of approximately 45 million years. Of totally 9281 editing events identified, 5150 (55.5%) are located in the coding sequences (CDS) of 2734 genes. Phylogenetic analysis places these genes into 1,526 homologous families, about 5% of total gene families in the fly lineages. Based on conservation of the editing sites, the editing events in CDS are categorized into three distinct types, representing events on singleton genes (type I), and events not conserved (type II) or conserved (type III) within multi-gene families. While both type I and II events are subject to purifying selection, notably type III events are positively selected, and highly enriched in the components and functions of the nervous system. The tissue profiles are documented for three editing types, and their critical roles are further implicated by their shifting patterns during holometabolous development and in post-mating response. In conclusion, three A-to-I RNA editing types are found to have distinct evolutionary dynamics. It appears that nervous system functions are mainly tested to determine if an A-to-I editing is beneficial for an organism. The coding plasticity enabled by A-to-I editing creates a new class of binary variations, which is a superior alternative to maintain heterozygosity of expressed genes in a diploid mating system. One prevalent form of RNA editing is the deamination of adenosines (A-to-I editing) in the precursor mRNA molecules, pertaining to most organisms in the metazoan lineage. While examples of A-to-I editing on critical genes have been known for years, it has not been fully characterized how A-to-I editing shapes the transcriptome and proteome in the evolution. To understand how A-to-I editing affects genes’ evolution and how itself is constrained by selection, we generated a global profile of A-to-I editing for a phylogeny of seven fly species, a model system representing an evolutionary timeframe of about 45 million years. We are focused on 5150 editing sites (of totally 9281 identified) located in the coding region of 2734 genes. Our analysis revealed the evolution dynamics of A-to-I editing sites and functional specificity of targeted genes. The shifting patterns of A-to-I editing are documented during holometabolous development and in post-mating response in flies. This work points to the important roles of regulated RNA editing in animal development and offers new insight into the evolution of A-to-I editing events and their harboring genes.
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77
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Fungtammasan A, Tomaszkiewicz M, Campos-Sánchez R, Eckert KA, DeGiorgio M, Makova KD. Reverse Transcription Errors and RNA-DNA Differences at Short Tandem Repeats. Mol Biol Evol 2016; 33:2744-58. [PMID: 27413049 PMCID: PMC5026258 DOI: 10.1093/molbev/msw139] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Transcript variation has important implications for organismal function in health and disease. Most transcriptome studies focus on assessing variation in gene expression levels and isoform representation. Variation at the level of transcript sequence is caused by RNA editing and transcription errors, and leads to nongenetically encoded transcript variants, or RNA–DNA differences (RDDs). Such variation has been understudied, in part because its detection is obscured by reverse transcription (RT) and sequencing errors. It has only been evaluated for intertranscript base substitution differences. Here, we investigated transcript sequence variation for short tandem repeats (STRs). We developed the first maximum-likelihood estimator (MLE) to infer RT error and RDD rates, taking next generation sequencing error rates into account. Using the MLE, we empirically evaluated RT error and RDD rates for STRs in a large-scale DNA and RNA replicated sequencing experiment conducted in a primate species. The RT error rates increased exponentially with STR length and were biased toward expansions. The RDD rates were approximately 1 order of magnitude lower than the RT error rates. The RT error rates estimated with the MLE from a primate data set were concordant with those estimated with an independent method, barcoded RNA sequencing, from a Caenorhabditis elegans data set. Our results have important implications for medical genomics, as STR allelic variation is associated with >40 diseases. STR nonallelic transcript variation can also contribute to disease phenotype. The MLE and empirical rates presented here can be used to evaluate the probability of disease-associated transcripts arising due to RDD.
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Affiliation(s)
- Arkarachai Fungtammasan
- Integrative Biosciences, Bioinformatics and Genomics Option, Pennsylvania State University Department of Biology, Pennsylvania State University Center for Medical Genomics, Pennsylvania State University Huck Institute of Genome Sciences, Pennsylvania State University
| | - Marta Tomaszkiewicz
- Department of Biology, Pennsylvania State University Center for Medical Genomics, Pennsylvania State University
| | - Rebeca Campos-Sánchez
- Department of Biology, Pennsylvania State University Center for Medical Genomics, Pennsylvania State University
| | - Kristin A Eckert
- Center for Medical Genomics, Pennsylvania State University Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, The Pennsylvania State University College of Medicine
| | - Michael DeGiorgio
- Department of Biology, Pennsylvania State University Center for Medical Genomics, Pennsylvania State University Institute for CyberScience, Pennsylvania State University
| | - Kateryna D Makova
- Department of Biology, Pennsylvania State University Center for Medical Genomics, Pennsylvania State University Huck Institute of Genome Sciences, Pennsylvania State University
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78
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Abstract
All true metazoans modify their RNAs by converting specific adenosine residues to inosine. Because inosine binds to cytosine, it is a biological mimic for guanosine. This subtle change, termed RNA editing, can have diverse effects on various RNA-mediated cellular pathways, including RNA interference, innate immunity, retrotransposon defense and messenger RNA recoding. Because RNA editing can be regulated, it is an ideal tool for increasing genetic diversity, adaptation and environmental acclimation. This review will cover the following themes related to RNA editing: (1) how it is used to modify different cellular RNAs, (2) how frequently it is used by different organisms to recode mRNA, (3) how specific recoding events regulate protein function, (4) how it is used in adaptation and (5) emerging evidence that it can be used for acclimation. Organismal biologists with an interest in adaptation and acclimation, but with little knowledge of RNA editing, are the intended audience.
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Affiliation(s)
- Joshua J C Rosenthal
- Universidad de Puerto Rico, Recinto de Ciencias Medicas, Instituto de Neurobiologia, 201 Blvd. del Valle, San Juan, PR 00901, USA
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79
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Solomon O, Eyal E, Amariglio N, Unger R, Rechavi G. e23D: database and visualization of A-to-I RNA editing sites mapped to 3D protein structures. Bioinformatics 2016; 32:2213-5. [DOI: 10.1093/bioinformatics/btw204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 04/09/2016] [Indexed: 11/13/2022] Open
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80
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Liu H, Wang Q, He Y, Chen L, Hao C, Jiang C, Li Y, Dai Y, Kang Z, Xu JR. Genome-wide A-to-I RNA editing in fungi independent of ADAR enzymes. Genome Res 2016; 26:499-509. [PMID: 26934920 PMCID: PMC4817773 DOI: 10.1101/gr.199877.115] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 01/22/2016] [Indexed: 01/10/2023]
Abstract
Yeasts and filamentous fungi do not have adenosine deaminase acting on RNA (ADAR) orthologs and are believed to lack A-to-I RNA editing, which is the most prevalent editing of mRNA in animals. However, during this study with the PUK1(FGRRES_01058) pseudokinase gene important for sexual reproduction in Fusarium graminearum, we found that two tandem stop codons, UA(1831)GUA(1834)G, in its kinase domain were changed to UG(1831)GUG(1834)G by RNA editing in perithecia. To confirm A-to-I editing of PUK1 transcripts, strand-specific RNA-seq data were generated with RNA isolated from conidia, hyphae, and perithecia. PUK1 was almost specifically expressed in perithecia, and 90% of transcripts were edited to UG(1831)GUG(1834)G. Genome-wide analysis identified 26,056 perithecium-specific A-to-I editing sites. Unlike those in animals, 70.5% of A-to-I editing sites inF. graminearum occur in coding regions, and more than two-thirds of them result in amino acid changes, including editing of 69PUK1-like pseudogenes with stop codons in ORFs.PUK1orthologs and other pseudogenes also displayed stage-specific expression and editing in Neurospora crassa and F. verticillioides Furthermore,F. graminearum differs from animals in the sequence preference and structure selectivity of A-to-I editing sites. Whereas A's embedded in RNA stems are targeted by ADARs, RNA editing inF. graminearum preferentially targets A's in hairpin loops, which is similar to the anticodon loop of tRNA targeted by adenosine deaminases acting on tRNA (ADATs). Overall, our results showed that A-to-I RNA editing occurs specifically during sexual reproduction and mainly in the coding regions in filamentous ascomycetes, involving adenosine deamination mechanisms distinct from metazoan ADARs.
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Affiliation(s)
- Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Qinhu Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yi He
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lingfeng Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Chaofeng Hao
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yang Li
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA
| | - Yafeng Dai
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jin-Rong Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China; Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA
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81
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Forni D, Mozzi A, Pontremoli C, Vertemara J, Pozzoli U, Biasin M, Bresolin N, Clerici M, Cagliani R, Sironi M. Diverse selective regimes shape genetic diversity at ADAR genes and at their coding targets. RNA Biol 2015; 12:149-61. [PMID: 25826567 DOI: 10.1080/15476286.2015.1017215] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
A-to-I RNA editing operated by ADAR enzymes is extremely common in mammals. Several editing events in coding regions have pivotal physiological roles and affect protein sequence (recoding events) or function. We analyzed the evolutionary history of the 3 ADAR family genes and of their coding targets. Evolutionary analysis indicated that ADAR evolved adaptively in primates, with the strongest selection in the unique N-terminal domain of the interferon-inducible isoform. Positively selected residues in the human lineage were also detected in the ADAR deaminase domain and in the RNA binding domains of ADARB1 and ADARB2. During the recent history of human populations distinct variants in the 3 genes increased in frequency as a result of local selective pressures. Most selected variants are located within regulatory regions and some are in linkage disequilibrium with eQTLs in monocytes. Finally, analysis of conservation scores of coding editing sites indicated that editing events are counter-selected within regions that are poorly tolerant to change. Nevertheless, a minority of recoding events occurs at highly conserved positions and possibly represents the functional fraction. These events are enriched in pathways related to HIV-1 infection and to epidermis/hair development. Thus, both ADAR genes and their targets evolved under variable selective regimes, including purifying and positive selection. Pressures related to immune response likely represented major drivers of evolution for ADAR genes. As for their coding targets, we suggest that most editing events are slightly deleterious, although a minority may be beneficial and contribute to antiviral response and skin homeostasis.
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Key Words
- 1000G,1000 Genomes Pilot Project
- A to I, adenosine to inosine
- A-to-I editing
- ADAR
- ADAR editing sites
- AGS, Aicardi-Goutières Syndrome
- BEB, Bayes Empirical Bayes
- BS-REL, branch site-random effects likelihood
- CEU, Europeans
- CHBJPT, Chinese plus Japanese
- DAF, derived allele frequency
- DIND, Derived Intra-allelic Nucleotide Diversity
- DSH, dyschromatosis symmetrica hereditaria
- FDR, false discovery rate
- GARD, Genetic Algorithm Recombination Detection
- GERP Genomic Evolutionary Rate Profiling
- IFN, Interferon
- LD, linkage disequilibrium
- LRT, likelihood ratio test
- MAF, minor allele frequency
- MEME, Mixed Effects Model of Evolution
- RBD, dsRNA binding domain
- SLAC, single-likelihood ancestor counting
- YRI, Yoruba
- eQTL, Expression quantitative trait loci
- evolutionary analysis
- iHS, Integrated Haplotype Score
- positive selection
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Affiliation(s)
- Diego Forni
- a Bioinformatics ; Scientific Institute IRCCS E. MEDEA ; Bosisio Parini , Italy
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82
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Deffit SN, Hundley HA. To edit or not to edit: regulation of ADAR editing specificity and efficiency. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 7:113-27. [PMID: 26612708 DOI: 10.1002/wrna.1319] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/15/2015] [Accepted: 10/20/2015] [Indexed: 11/08/2022]
Abstract
Hundreds to millions of adenosine (A)-to-inosine (I) modifications are present in eukaryotic transcriptomes and play an essential role in the creation of proteomic and phenotypic diversity. As adenosine and inosine have different base-pairing properties, the functional consequences of these modifications or 'edits' include altering coding potential, splicing, and miRNA-mediated gene silencing of transcripts. However, rather than serving as a static control of gene expression, A-to-I editing provides a means to dynamically rewire the genetic code during development and in a cell-type specific manner. Interestingly, during normal development, in specific cells, and in both neuropathological diseases and cancers, the extent of RNA editing does not directly correlate with levels of the substrate mRNA or the adenosine deaminase that act on RNA (ADAR) editing enzymes, implying that cellular factors are required for spatiotemporal regulation of A-to-I editing. The factors that affect the specificity and extent of ADAR activity have been thoroughly dissected in vitro. Yet, we still lack a complete understanding of how specific ADAR family members can selectively deaminate certain adenosines while others cannot. Additionally, in the cellular environment, ADAR specificity and editing efficiency is likely to be influenced by cellular factors, which is currently an area of intense investigation. Data from many groups have suggested two main mechanisms for controlling A-to-I editing in the cell: (1) regulating ADAR accessibility to target RNAs and (2) protein-protein interactions that directly alter ADAR enzymatic activity. Recent studies suggest cis- and trans-acting RNA elements, heterodimerization and RNA-binding proteins play important roles in regulating RNA editing levels in vivo. WIREs RNA 2016, 7:113-127. doi: 10.1002/wrna.1319.
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Affiliation(s)
- Sarah N Deffit
- Medical Sciences Program, Indiana University, Bloomington, IN, USA
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83
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Paz-Yaacov N, Bazak L, Buchumenski I, Porath HT, Danan-Gotthold M, Knisbacher BA, Eisenberg E, Levanon EY. Elevated RNA Editing Activity Is a Major Contributor to Transcriptomic Diversity in Tumors. Cell Rep 2015; 13:267-76. [PMID: 26440895 DOI: 10.1016/j.celrep.2015.08.080] [Citation(s) in RCA: 230] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 07/02/2015] [Accepted: 08/28/2015] [Indexed: 01/08/2023] Open
Abstract
Genomic mutations in key genes are known to drive tumorigenesis and have been the focus of much attention in recent years. However, genetic content also may change farther downstream. RNA editing alters the mRNA sequence from its genomic blueprint in a dynamic and flexible way. A few isolated cases of editing alterations in cancer have been reported previously. Here, we provide a transcriptome-wide characterization of RNA editing across hundreds of cancer samples from multiple cancer tissues, and we show that A-to-I editing and the enzymes mediating this modification are significantly altered, usually elevated, in most cancer types. Increased editing activity is found to be associated with patient survival. As is the case with somatic mutations in DNA, most of these newly introduced RNA mutations are likely passengers, but a few may serve as drivers that may be novel candidates for therapeutic and diagnostic purposes.
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Affiliation(s)
- Nurit Paz-Yaacov
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Lily Bazak
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ilana Buchumenski
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Hagit T Porath
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Miri Danan-Gotthold
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Binyamin A Knisbacher
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Eli Eisenberg
- School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Erez Y Levanon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel.
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84
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RNA editing differently affects protein-coding genes in D. melanogaster and H. sapiens. Sci Rep 2015; 5:11550. [PMID: 26169954 PMCID: PMC4648400 DOI: 10.1038/srep11550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/13/2015] [Indexed: 11/08/2022] Open
Abstract
When an RNA editing event occurs within a coding sequence it can lead to a different encoded amino acid. The biological significance of these events remains an open question: they can modulate protein functionality, increase the complexity of transcriptomes or arise from a loose specificity of the involved enzymes. We analysed the editing events in coding regions that produce or not a change in the encoded amino acid (nonsynonymous and synonymous events, respectively) in D. melanogaster and in H. sapiens and compared them with the appropriate random models. Interestingly, our results show that the phenomenon has rather different characteristics in the two organisms. For example, we confirm the observation that editing events occur more frequently in non-coding than in coding regions, and report that this effect is much more evident in H. sapiens. Additionally, in this latter organism, editing events tend to affect less conserved residues. The less frequently occurring editing events in Drosophila tend to avoid drastic amino acid changes. Interestingly, we find that, in Drosophila, changes from less frequently used codons to more frequently used ones are favoured, while this is not the case in H. sapiens.
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85
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Abstract
The rate and mechanism of protein sequence evolution have been central questions in evolutionary biology since the 1960s. Although the rate of protein sequence evolution depends primarily on the level of functional constraint, exactly what determines functional constraint has remained unclear. The increasing availability of genomic data has enabled much needed empirical examinations on the nature of functional constraint. These studies found that the evolutionary rate of a protein is predominantly influenced by its expression level rather than functional importance. A combination of theoretical and empirical analyses has identified multiple mechanisms behind these observations and demonstrated a prominent role in protein evolution of selection against errors in molecular and cellular processes.
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Affiliation(s)
- Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, 830 North University Avenue, Ann Arbor, Michigan 48109, USA
| | - Jian-Rong Yang
- Department of Ecology and Evolutionary Biology, University of Michigan, 830 North University Avenue, Ann Arbor, Michigan 48109, USA
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86
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Knisbacher BA, Levanon EY. DNA and RNA editing of retrotransposons accelerate mammalian genome evolution. Ann N Y Acad Sci 2015; 1341:115-25. [PMID: 25722083 DOI: 10.1111/nyas.12713] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Genome evolution is commonly viewed as a gradual process that is driven by random mutations that accumulate over time. However, DNA- and RNA-editing enzymes have been identified that can accelerate evolution by actively modifying the genomically encoded information. The apolipoprotein B mRNA editing enzymes, catalytic polypeptide-like (APOBECs) are potent restriction factors that can inhibit retroelements by cytosine-to-uridine editing of retroelement DNA after reverse transcription. In some cases, a retroelement may successfully integrate into the genome despite being hypermutated. Such events introduce unique sequences into the genome and are thus a source of genomic innovation. adenosine deaminases that act on RNA (ADARs) catalyze adenosine-to-inosine editing in double-stranded RNA, commonly formed by oppositely oriented retroelements. The RNA editing confers plasticity to the transcriptome by generating many transcript variants from a single genomic locus. If the editing produces a beneficial variant, the genome may maintain the locus that produces the RNA-edited transcript for its novel function. Here, we discuss how these two powerful editing mechanisms, which both target inserted retroelements, facilitate expedited genome evolution.
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Affiliation(s)
- Binyamin A Knisbacher
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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87
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Chen T, Xiang JF, Zhu S, Chen S, Yin QF, Zhang XO, Zhang J, Feng H, Dong R, Li XJ, Yang L, Chen LL. ADAR1 is required for differentiation and neural induction by regulating microRNA processing in a catalytically independent manner. Cell Res 2015; 25:459-76. [PMID: 25708366 DOI: 10.1038/cr.2015.24] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 11/09/2014] [Accepted: 12/01/2014] [Indexed: 02/08/2023] Open
Abstract
Adenosine deaminases acting on RNA (ADARs) are involved in adenosine-to-inosine RNA editing and are implicated in development and diseases. Here we observed that ADAR1 deficiency in human embryonic stem cells (hESCs) significantly affected hESC differentiation and neural induction with widespread changes in mRNA and miRNA expression, including upregulation of self-renewal-related miRNAs, such as miR302s. Global editing analyses revealed that ADAR1 editing activity contributes little to the altered miRNA/mRNA expression in ADAR1-deficient hESCs upon neural induction. Genome-wide iCLIP studies identified that ADAR1 binds directly to pri-miRNAs to interfere with miRNA processing by acting as an RNA-binding protein. Importantly, aberrant expression of miRNAs and phenotypes observed in ADAR1-depleted hESCs upon neural differentiation could be reversed by an enzymatically inactive ADAR1 mutant, but not by the RNA-binding-null ADAR1 mutant. These findings reveal that ADAR1, but not its editing activity, is critical for hESC differentiation and neural induction by regulating miRNA biogenesis via direct RNA interaction.
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Affiliation(s)
- Tian Chen
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jian-Feng Xiang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Shanshan Zhu
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Brain Science, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Siye Chen
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Qing-Fei Yin
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiao-Ou Zhang
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Brain Science, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jun Zhang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Hua Feng
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Brain Science, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Rui Dong
- CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Brain Science, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xue-Jun Li
- Department of Neuroscience, University of Connecticut Stem Cell Institute, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Li Yang
- 1] CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Brain Science, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China [2] School of Life Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Ling-Ling Chen
- 1] State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China [2] School of Life Science and Technology, ShanghaiTech University, Shanghai 200031, China
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88
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Schweidenback CTH, Emerman AB, Jambhekar A, Blower MD. Evidence for multiple, distinct ADAR-containing complexes in Xenopus laevis. RNA (NEW YORK, N.Y.) 2015; 21:279-295. [PMID: 25519486 PMCID: PMC4338354 DOI: 10.1261/rna.047787.114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 11/20/2014] [Indexed: 06/04/2023]
Abstract
ADAR (adenosine deaminase acting on RNA) is an RNA-editing enzyme present in most metazoans that converts adenosines in double-stranded RNA targets into inosines. Although the RNA targets of ADAR-mediated editing have been extensively cataloged, our understanding of the cellular function of such editing remains incomplete. We report that long, double-stranded RNA added to Xenopus laevis egg extract is incorporated into an ADAR-containing complex whose protein components resemble those of stress granules. This complex localizes to microtubules, as assayed by accumulation on meiotic spindles. We observe that the length of a double-stranded RNA influences its incorporation into the microtubule-localized complex. ADAR forms a similar complex with endogenous RNA, but the endogenous complex fails to localize to microtubules. In addition, we characterize the endogenous, ADAR-associated RNAs and discover that they are enriched for transcripts encoding transcriptional regulators, zinc-finger proteins, and components of the secretory pathway. Interestingly, association with ADAR correlates with previously reported translational repression in early embryonic development. This work demonstrates that ADAR is a component of two, distinct ribonucleoprotein complexes that contain different types of RNAs and exhibit diverse cellular localization patterns. Our findings offer new insight into the potential cellular functions of ADAR.
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Affiliation(s)
- Caterina T H Schweidenback
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Amy B Emerman
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Ashwini Jambhekar
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Michael D Blower
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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89
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Palazzo AF, Lee ES. Non-coding RNA: what is functional and what is junk? Front Genet 2015; 6:2. [PMID: 25674102 PMCID: PMC4306305 DOI: 10.3389/fgene.2015.00002] [Citation(s) in RCA: 501] [Impact Index Per Article: 55.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/06/2015] [Indexed: 12/12/2022] Open
Abstract
The genomes of large multicellular eukaryotes are mostly comprised of non-protein coding DNA. Although there has been much agreement that a small fraction of these genomes has important biological functions, there has been much debate as to whether the rest contributes to development and/or homeostasis. Much of the speculation has centered on the genomic regions that are transcribed into RNA at some low level. Unfortunately these RNAs have been arbitrarily assigned various names, such as “intergenic RNA,” “long non-coding RNAs” etc., which have led to some confusion in the field. Many researchers believe that these transcripts represent a vast, unchartered world of functional non-coding RNAs (ncRNAs), simply because they exist. However, there are reasons to question this Panglossian view because it ignores our current understanding of how evolution shapes eukaryotic genomes and how the gene expression machinery works in eukaryotic cells. Although there are undoubtedly many more functional ncRNAs yet to be discovered and characterized, it is also likely that many of these transcripts are simply junk. Here, we discuss how to determine whether any given ncRNA has a function. Importantly, we advocate that in the absence of any such data, the appropriate null hypothesis is that the RNA in question is junk.
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Affiliation(s)
| | - Eliza S Lee
- Department of Biochemistry, University of Toronto Toronto, ON, Canada
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90
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Alon S, Garrett SC, Levanon EY, Olson S, Graveley BR, Rosenthal JJC, Eisenberg E. The majority of transcripts in the squid nervous system are extensively recoded by A-to-I RNA editing. eLife 2015; 4. [PMID: 25569156 PMCID: PMC4384741 DOI: 10.7554/elife.05198] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 01/08/2015] [Indexed: 12/29/2022] Open
Abstract
RNA editing by adenosine deamination alters genetic information from the genomic
blueprint. When it recodes mRNAs, it gives organisms the option to express diverse,
functionally distinct, protein isoforms. All eumetazoans, from cnidarians to humans,
express RNA editing enzymes. However, transcriptome-wide screens have only uncovered
about 25 transcripts harboring conserved recoding RNA editing sites in mammals and
several hundred recoding sites in Drosophila. These studies on few
established models have led to the general assumption that recoding by RNA editing is
extremely rare. Here we employ a novel bioinformatic approach with extensive
validation to show that the squid Doryteuthis pealeii recodes
proteins by RNA editing to an unprecedented extent. We identify 57,108 recoding sites
in the nervous system, affecting the majority of the proteins studied. Recoding is
tissue-dependent, and enriched in genes with neuronal and cytoskeletal functions,
suggesting it plays an important role in brain physiology. DOI:http://dx.doi.org/10.7554/eLife.05198.001 For living cells to create a protein, a genetic code found in its DNA must first be
‘transcribed’ to create a corresponding molecule of messenger RNA
(mRNA). DNA and RNA are both made from smaller molecules called nucleotides that are
linked together into long chains; the information in both DNA and RNA is contained in
the sequence of these molecules. The mRNA nucleotides coding for proteins are
‘translated’ in groups of three, and most of these nucleotide triplets
instruct for a specific amino acid to be added to the newly forming protein. DNA sequences were thought to exactly correspond with the sequence of amino acids in
the resulting protein. However, it is now known that processes called RNA editing can
change the nucleotide sequence of the mRNA molecules after they have been transcribed
from the DNA. One such editing process, called A-to-I editing, alters the
‘A’ nucleotide so that the translation machinery reads it as a
‘G’ nucleotide instead. In some—but not all—cases, this
event will change, or ‘recode’, the amino acid encoded by this stretch
of mRNA, which may change how the protein behaves. This ability to create a range of
proteins from a single DNA sequence could help organisms to evolve new traits. Evidence of amino acid recoding has only been found to a very limited extent in the
few species investigated so far. There has been some evidence that suggests that
recoding might occur more often, and alter more proteins, in squids and octopuses.
However, this could not be confirmed as the genomes of these species have not been
sequenced, and these sequences were required to investigate RNA recoding using
existing techniques. Alon et al. have now developed a new approach that allows the recoding sites to be
identified in organisms whose genomes have not been sequenced. Using this
technique—which compares mRNA sequences with the DNA sequence they have been
transcribed from—to examine the squid nervous system revealed over 57,000
recoding sites where an ‘A’ nucleotide had been modified to
‘G’ and thereby changed the coded amino acid. Many of the identified
mRNA molecules had been recoded in more than one place, and many more of these than
expected changed the amino acid sequence of the protein translated from them. Alon et
al. therefore suggest that RNA editing may have been crucial in the evolution of the
squid's nervous system, and suggest that recoding should be considered a normal part
of the process used by squids to make proteins. DOI:http://dx.doi.org/10.7554/eLife.05198.002
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Affiliation(s)
- Shahar Alon
- George S Wise Faculty of Life Sciences, Department of Neurobiology, Tel Aviv University, Tel Aviv, Israel
| | - Sandra C Garrett
- Department of Genetics and Developmental Biology, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, United States
| | - Erez Y Levanon
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Sara Olson
- Department of Genetics and Developmental Biology, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, United States
| | - Brenton R Graveley
- Department of Genetics and Developmental Biology, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, United States
| | - Joshua J C Rosenthal
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Eli Eisenberg
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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91
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Zhao HQ, Zhang P, Gao H, He X, Dou Y, Huang AY, Liu XM, Ye AY, Dong MQ, Wei L. Profiling the RNA editomes of wild-type C. elegans and ADAR mutants. Genome Res 2015; 25:66-75. [PMID: 25373143 PMCID: PMC4317174 DOI: 10.1101/gr.176107.114] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 10/29/2014] [Indexed: 01/08/2023]
Abstract
RNA editing increases transcriptome diversity through post-transcriptional modifications of RNA. Adenosine deaminases that act on RNA (ADARs) catalyze the adenosine-to-inosine (A-to-I) conversion, the most common type of RNA editing in higher eukaryotes. Caenorhabditis elegans has two ADARs, ADR-1 and ADR-2, but their functions remain unclear. Here, we profiled the RNA editomes of C. elegans at different developmental stages of wild-type and ADAR mutants. We developed a new computational pipeline with a "bisulfite-seq-mapping-like" step and achieved a threefold increase in identification sensitivity. A total of 99.5% of the 47,660 A-to-I editing sites were found in clusters. Of the 3080 editing clusters, 65.7% overlapped with DNA transposons in noncoding regions and 73.7% could form hairpin structures. The numbers of editing sites and clusters were highest at the L1 and embryonic stages. The editing frequency of a cluster positively correlated with the number of editing sites within it. Intriguingly, for 80% of the clusters with 10 or more editing sites, almost all expressed transcripts were edited. Deletion of adr-1 reduced the editing frequency but not the number of editing clusters, whereas deletion of adr-2 nearly abolished RNA editing, indicating a modulating role of ADR-1 and an essential role of ADR-2 in A-to-I editing. Quantitative proteomics analysis showed that adr-2 mutant worms altered the abundance of proteins involved in aging and lifespan regulation. Consistent with this finding, we observed that worms lacking RNA editing were short-lived. Taken together, our results reveal a sophisticated landscape of RNA editing and distinct modes of action of different ADARs.
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Affiliation(s)
- Han-Qing Zhao
- National Institute of Biological Sciences, Beijing 102206, China
| | - Pan Zhang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Hua Gao
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Xiandong He
- National Institute of Biological Sciences, Beijing 102206, China
| | - Yanmei Dou
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - August Y Huang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Xi-Ming Liu
- National Institute of Biological Sciences, Beijing 102206, China
| | - Adam Y Ye
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing 102206, China;
| | - Liping Wei
- National Institute of Biological Sciences, Beijing 102206, China; Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
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92
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Abstract
RNA editing is a posttranscriptional modification that can lead to a change in the encoded protein sequence of a gene. Although a few cases of mammalian coding RNA editing are known to be functionally important, the vast majority of over 2,000 A-to-I editing sites that have been identified from the coding regions of the human genome are likely nonadaptive, representing tolerable promiscuous targeting of editing enzymes. Finding the potentially tiny fraction of beneficial editing sites from the sea of mostly nearly neutral editing is a difficult but important task. Here, we propose and provide evidence that evolutionarily conserved or "hardwired" residues that experience high-level nonsynonymous RNA editing in a species are enriched with beneficial editing. This simple approach allows the prediction of sites where RNA editing is functionally important. We suggest that priority be given to these candidates in future characterizations of the functional and fitness consequences of RNA editing.
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Affiliation(s)
- Guixia Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan
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93
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Solomon O, Bazak L, Levanon EY, Amariglio N, Unger R, Rechavi G, Eyal E. Characterizing of functional human coding RNA editing from evolutionary, structural, and dynamic perspectives. Proteins 2014; 82:3117-31. [DOI: 10.1002/prot.24672] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/28/2014] [Accepted: 08/11/2014] [Indexed: 12/29/2022]
Affiliation(s)
- Oz Solomon
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Lily Bazak
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Erez Y. Levanon
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Ninette Amariglio
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
| | - Ron Unger
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Gideon Rechavi
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv 69978 Israel
| | - Eran Eyal
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
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94
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Liu H, Ma CP, Chen YT, Schuyler SC, Chang KP, Tan BCM. Functional Impact of RNA editing and ADARs on regulation of gene expression: perspectives from deep sequencing studies. Cell Biosci 2014; 4:44. [PMID: 25949793 PMCID: PMC4422215 DOI: 10.1186/2045-3701-4-44] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/14/2014] [Indexed: 11/13/2022] Open
Abstract
Cells regulate gene expression at multiple levels leading to a balance between robustness and complexity within their proteome. One core molecular step contributing to this important balance during metazoan gene expression is RNA editing, such as the co-transcriptional recoding of RNA transcripts catalyzed by the adenosine deaminse acting on RNA (ADAR) family of enzymes. Understanding of the adenosine-to-inosine RNA editing process has been broadened considerably by the next generation sequencing (NGS) technology, which allows for in-depth demarcation of an RNA editome at nucleotide resolution. However, critical issues remain unresolved with regard to how RNA editing cooperates with other transcript-associated events to underpin regulated gene expression. Here we review the growing body of evidence, provided by recent NGS-based studies, that links RNA editing to other mechanisms of post-transcriptional RNA processing and gene expression regulation including alternative splicing, transcript stability and localization, and the biogenesis and function of microRNAs (miRNAs). We also discuss the possibility that systematic integration of NGS data may be employed to establish the rules of an “RNA editing code”, which may give us new insights into the functional consequences of RNA editing.
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Affiliation(s)
- Hsuan Liu
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan ; Department of Biochemistry, Tao-Yuan, Taiwan ; Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan
| | - Chung-Pei Ma
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan
| | - Yi-Tung Chen
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan
| | - Scott C Schuyler
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan ; Department of Biomedical Sciences, College of Medicine, Tao-Yuan, Taiwan
| | - Kai-Ping Chang
- Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan ; Department of Otolaryngology, Chang Gung Memorial Hospital at Lin-Kuo, Tao-Yuan, Taiwan
| | - Bertrand Chin-Ming Tan
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan ; Department of Biomedical Sciences, College of Medicine, Tao-Yuan, Taiwan ; Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan
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