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Melamed D, Nov Y, Malik A, Yakass MB, Bolotin E, Shemer R, Hiadzi EK, Skorecki KL, Livnat A. De novo mutation rates at the single-mutation resolution in a human HBB gene-region associated with adaptation and genetic disease. Genome Res 2022; 32:488-498. [PMID: 35031571 PMCID: PMC8896469 DOI: 10.1101/gr.276103.121] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 01/10/2022] [Indexed: 11/25/2022]
Abstract
Although it is known that the mutation rate varies across the genome, previous estimates were based on averaging across various numbers of positions. Here, we describe a method to measure the origination rates of target mutations at target base positions and apply it to a 6-bp region in the human hemoglobin subunit beta (HBB) gene and to the identical, paralogous hemoglobin subunit delta (HBD) region in sperm cells from both African and European donors. The HBB region of interest (ROI) includes the site of the hemoglobin S (HbS) mutation, which protects against malaria, is common in Africa, and has served as a classic example of adaptation by random mutation and natural selection. We found a significant correspondence between de novo mutation rates and past observations of alleles in carriers, showing that mutation rates vary substantially in a mutation-specific manner that contributes to the site frequency spectrum. We also found that the overall point mutation rate is significantly higher in Africans than in Europeans in the HBB region studied. Finally, the rate of the 20A→T mutation, called the “HbS mutation” when it appears in HBB, is significantly higher than expected from the genome-wide average for this mutation type. Nine instances were observed in the African HBB ROI, where it is of adaptive significance, representing at least three independent originations; no instances were observed elsewhere. Further studies will be needed to examine mutation rates at the single-mutation resolution across these and other loci and organisms and to uncover the molecular mechanisms responsible.
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52
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Cruz J, Lemos B. Post-transcriptional diversity in riboproteins and RNAs in aging and cancer. Semin Cancer Biol 2021; 76:292-300. [PMID: 34474152 PMCID: PMC8627441 DOI: 10.1016/j.semcancer.2021.08.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 08/28/2021] [Accepted: 08/29/2021] [Indexed: 12/19/2022]
Abstract
Post-transcriptional (PtscM) and post-translational (PtrnM) modifications of nucleotides and amino acids are covalent modifications able to change physio-chemical properties of RNAs and proteins. In the ribosome, the adequate assembly of rRNAs and ribosomal protein subunits in the nucleolus ensures suitable translational activity, with protein synthesis tuned according to intracellular demands of energy production, replication, proliferation, and growth. Disruption in the regulatory control of PtscM and PtrnM can impair ribosome biogenesis and ribosome function. Ribosomal impairment may, in turn, impact the synthesis of proteins engaged in functions as varied as telomere maintenance, apoptosis, and DNA repair, as well as intersect with mitochondria and telomerase activity. These cellular processes often malfunction in carcinogenesis and senescence. Here we discuss regulatory mechanisms of PtscMs and PtrnMs on ribosomal function. We also address chemical modification in rRNAs and their impacts on cellular metabolism, replication control, and senescence. Further, we highlight similarities and differences of PtscMs and PtrnMs in ribosomal intermediates during aging and carcinogenesis. Understanding these regulatory mechanisms may uncover critical steps for the development of more efficient oncologic and anti-aging therapies.
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Affiliation(s)
- Jurandir Cruz
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA; Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP 01246, Brazil
| | - Bernardo Lemos
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
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53
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Valadon C, Namy O. The Importance of the Epi-Transcriptome in Translation Fidelity. Noncoding RNA 2021; 7:51. [PMID: 34564313 PMCID: PMC8482273 DOI: 10.3390/ncrna7030051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/17/2021] [Accepted: 08/22/2021] [Indexed: 12/11/2022] Open
Abstract
RNA modifications play an essential role in determining RNA fate. Recent studies have revealed the effects of such modifications on all steps of RNA metabolism. These modifications range from the addition of simple groups, such as methyl groups, to the addition of highly complex structures, such as sugars. Their consequences for translation fidelity are not always well documented. Unlike the well-known m6A modification, they are thought to have direct effects on either the folding of the molecule or the ability of tRNAs to bind their codons. Here we describe how modifications found in tRNAs anticodon-loop, rRNA, and mRNA can affect translation fidelity, and how approaches based on direct manipulations of the level of RNA modification could potentially be used to modulate translation for the treatment of human genetic diseases.
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Affiliation(s)
| | - Olivier Namy
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France;
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54
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Rengaraj P, Obrdlík A, Vukić D, Varadarajan NM, Keegan LP, Vaňáčová Š, O'Connell MA. Interplays of different types of epitranscriptomic mRNA modifications. RNA Biol 2021; 18:19-30. [PMID: 34424827 PMCID: PMC8677042 DOI: 10.1080/15476286.2021.1969113] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Eukaryotic mRNAs are modified by several chemical marks which have significant impacts on mRNA biology, gene expression, and cellular metabolism as well as on the survival and development of the whole organism. The most abundant and well-studied mRNA base modifications are m6A and ADAR RNA editing. Recent studies have also identified additional mRNA marks such as m6Am, m5C, m1A and Ψ and studied their roles. Each type of modification is deposited by a specific writer, many types of modification are recognized and interpreted by several different readers and some types of modifications can be removed by eraser enzymes. Several works have addressed the functional relationships between some of the modifications. In this review we provide an overview on the current status of research on the different types of mRNA modifications and about the crosstalk between different marks and its functional consequences.
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Affiliation(s)
- Praveenkumar Rengaraj
- Central European Institute of Technology (CEITEC), CEITEC, Masaryk University Brno, Brno, Czech Republic
| | - Aleš Obrdlík
- Central European Institute of Technology (CEITEC), CEITEC, Masaryk University Brno, Brno, Czech Republic
| | - Dragana Vukić
- Central European Institute of Technology (CEITEC), CEITEC, Masaryk University Brno, Brno, Czech Republic
| | - Nandan Mysore Varadarajan
- Central European Institute of Technology (CEITEC), CEITEC, Masaryk University Brno, Brno, Czech Republic
| | - Liam P Keegan
- Central European Institute of Technology (CEITEC), CEITEC, Masaryk University Brno, Brno, Czech Republic
| | - Štěpánka Vaňáčová
- Central European Institute of Technology (CEITEC), CEITEC, Masaryk University Brno, Brno, Czech Republic
| | - Mary A O'Connell
- Central European Institute of Technology (CEITEC), CEITEC, Masaryk University Brno, Brno, Czech Republic
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55
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Shoshan Y, Liscovitch-Brauer N, Rosenthal JJC, Eisenberg E. Adaptive Proteome Diversification by Nonsynonymous A-to-I RNA Editing in Coleoid Cephalopods. Mol Biol Evol 2021; 38:3775-3788. [PMID: 34022057 PMCID: PMC8382921 DOI: 10.1093/molbev/msab154] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
RNA editing by the ADAR enzymes converts selected adenosines into inosines, biological mimics for guanosines. By doing so, it alters protein-coding sequences, resulting in novel protein products that diversify the proteome beyond its genomic blueprint. Recoding is exceptionally abundant in the neural tissues of coleoid cephalopods (octopuses, squids, and cuttlefishes), with an over-representation of nonsynonymous edits suggesting positive selection. However, the extent to which proteome diversification by recoding provides an adaptive advantage is not known. It was recently suggested that the role of evolutionarily conserved edits is to compensate for harmful genomic substitutions, and that there is no added value in having an editable codon as compared with a restoration of the preferred genomic allele. Here, we show that this hypothesis fails to explain the evolutionary dynamics of recoding sites in coleoids. Instead, our results indicate that a large fraction of the shared, strongly recoded, sites in coleoids have been selected for proteome diversification, meaning that the fitness of an editable A is higher than an uneditable A or a genomically encoded G.
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Affiliation(s)
- Yoav Shoshan
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - Noa Liscovitch-Brauer
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | | | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
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56
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Ojha N, Diaz Quiroz JF, Rosenthal JJC. In vitro and in cellula site-directed RNA editing using the λNDD-BoxB system. Methods Enzymol 2021; 658:335-358. [PMID: 34517953 DOI: 10.1016/bs.mie.2021.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Site-directed RNA editing (SDRE) exploits the enzymatic activity of Adenosine Deaminases Acting on RNAs (ADAR) to program changes in genetic information as it passes through RNA. ADARs convert adenosine (A) to inosine (I) through a hydrolytic deamination and since I can be read as guanosine (G) during translation, this change can regulate gene function and correct G→A genetic mutations. In SDRE, ADARs are redirected to convert user-defined A's to I's. SDRE also has certain advantages over genome editing because the changes in RNA are reversible and thus safer. In addition, ADARs are endogenously expressed in humans and therefore unlikely to provoke immunological complications when administered. Recently, a variety of systems for SDRE have been developed. Some rely on harnessing endogenously expressed ADARs and other deliver engineered versions of ADAR's catalytic domain. All systems are currently under refinement, and there are still challenges associated with raising their efficiency and specificity to levels that are adequate for therapeutics. This chapter provides a detailed protocol for in vitro and in cellula editing assays using the λNDD-BoxB system, one of the first systems developed for SDRE. The λNDD-BoxB system relies on gRNAs that are linked to the catalytic domain of human ADAR2 through a small RNA binding protein-RNA stem/loop interaction. We provide step-by-step protocols for (a) the construction of guide RNAs and editing enzyme plasmids, and (b) their use in vitro and in cellula for editing assays using a fluorescent protein-based reporter system containing a premature termination codon that can be corrected by editing.
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Affiliation(s)
- Namrata Ojha
- The Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, MA, United States
| | | | - Joshua J C Rosenthal
- The Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, MA, United States.
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57
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Tang T, Han Y, Wang Y, Huang H, Qian P. Programmable System of Cas13-Mediated RNA Modification and Its Biological and Biomedical Applications. Front Cell Dev Biol 2021; 9:677587. [PMID: 34386490 PMCID: PMC8353156 DOI: 10.3389/fcell.2021.677587] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/16/2021] [Indexed: 12/15/2022] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas13 has drawn broad interest to control gene expression and cell fate at the RNA level in general. Apart from RNA interference mediated by its endonuclease activity, the nuclease-deactivated form of Cas13 further provides a versatile RNA-guided RNA-targeting platform for manipulating kinds of RNA modifications post-transcriptionally. Chemical modifications modulate various aspects of RNA fate, including translation efficiency, alternative splicing, RNA–protein affinity, RNA–RNA interaction, RNA stability and RNA translocation, which ultimately orchestrate cellular biologic activities. This review summarizes the history of the CRISPR-Cas13 system, fundamental components of RNA modifications and the related physiological and pathological functions. We focus on the development of epi-transcriptional editing toolkits based on catalytically inactive Cas13, including RNA Editing for Programmable A to I Replacement (REPAIR) and xABE (adenosine base editor) for adenosine deamination, RNA Editing for Specific C-to-U Exchange (RESCUE) and xCBE (cytidine base editor) for cytidine deamination and dm6ACRISPR, as well as the targeted RNA methylation (TRM) and photoactivatable RNA m6A editing system using CRISPR-dCas13 (PAMEC) for m6A editing. We further highlight the emerging applications of these useful toolkits in cell biology, disease and imaging. Finally, we discuss the potential limitations, such as off-target editing, low editing efficiency and limitation for AAV delivery, and provide possible optimization strategies.
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Affiliation(s)
- Tian Tang
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
| | - Yingli Han
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
| | - Yuran Wang
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
| | - He Huang
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China
| | - Pengxu Qian
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
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58
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Torres AG, Rodríguez-Escribà M, Marcet-Houben M, Santos Vieira H, Camacho N, Catena H, Murillo Recio M, Rafels-Ybern À, Reina O, Torres F, Pardo-Saganta A, Gabaldón T, Novoa E, Ribas de Pouplana L. Human tRNAs with inosine 34 are essential to efficiently translate eukarya-specific low-complexity proteins. Nucleic Acids Res 2021; 49:7011-7034. [PMID: 34125917 PMCID: PMC8266599 DOI: 10.1093/nar/gkab461] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/07/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022] Open
Abstract
The modification of adenosine to inosine at the wobble position (I34) of tRNA anticodons is an abundant and essential feature of eukaryotic tRNAs. The expansion of inosine-containing tRNAs in eukaryotes followed the transformation of the homodimeric bacterial enzyme TadA, which generates I34 in tRNAArg and tRNALeu, into the heterodimeric eukaryotic enzyme ADAT, which modifies up to eight different tRNAs. The emergence of ADAT and its larger set of substrates, strongly influenced the tRNA composition and codon usage of eukaryotic genomes. However, the selective advantages that drove the expansion of I34-tRNAs remain unknown. Here we investigate the functional relevance of I34-tRNAs in human cells and show that a full complement of these tRNAs is necessary for the translation of low-complexity protein domains enriched in amino acids cognate for I34-tRNAs. The coding sequences for these domains require codons translated by I34-tRNAs, in detriment of synonymous codons that use other tRNAs. I34-tRNA-dependent low-complexity proteins are enriched in functional categories related to cell adhesion, and depletion in I34-tRNAs leads to cellular phenotypes consistent with these roles. We show that the distribution of these low-complexity proteins mirrors the distribution of I34-tRNAs in the phylogenetic tree.
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Affiliation(s)
- Adrian Gabriel Torres
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Marta Rodríguez-Escribà
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Marina Marcet-Houben
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
- Barcelona Supercomputing Centre (BSC-CNS), Barcelona, Catalonia 08034, Spain
| | | | - Noelia Camacho
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Helena Catena
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Marina Murillo Recio
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Àlbert Rafels-Ybern
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Oscar Reina
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Francisco Miguel Torres
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
| | - Ana Pardo-Saganta
- Centre for Applied Medical Research (CIMA Universidad de Navarra), Pamplona 31008, Spain
| | - Toni Gabaldón
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
- Barcelona Supercomputing Centre (BSC-CNS), Barcelona, Catalonia 08034, Spain
- Catalan Institution for Research and Advanced Studies, Barcelona, Catalonia 08010, Spain
| | - Eva Maria Novoa
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08003, Spain
- University Pompeu Fabra, Barcelona, Catalonia 08003, Spain
| | - Lluís Ribas de Pouplana
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Catalonia 08028, Spain
- Catalan Institution for Research and Advanced Studies, Barcelona, Catalonia 08010, Spain
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59
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From Antisense RNA to RNA Modification: Therapeutic Potential of RNA-Based Technologies. Biomedicines 2021; 9:biomedicines9050550. [PMID: 34068948 PMCID: PMC8156014 DOI: 10.3390/biomedicines9050550] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 02/07/2023] Open
Abstract
Therapeutic oligonucleotides interact with a target RNA via Watson-Crick complementarity, affecting RNA-processing reactions such as mRNA degradation, pre-mRNA splicing, or mRNA translation. Since they were proposed decades ago, several have been approved for clinical use to correct genetic mutations. Three types of mechanisms of action (MoA) have emerged: RNase H-dependent degradation of mRNA directed by short chimeric antisense oligonucleotides (gapmers), correction of splicing defects via splice-modulation oligonucleotides, and interference of gene expression via short interfering RNAs (siRNAs). These antisense-based mechanisms can tackle several genetic disorders in a gene-specific manner, primarily by gene downregulation (gapmers and siRNAs) or splicing defects correction (exon-skipping oligos). Still, the challenge remains for the repair at the single-nucleotide level. The emerging field of epitranscriptomics and RNA modifications shows the enormous possibilities for recoding the transcriptome and repairing genetic mutations with high specificity while harnessing endogenously expressed RNA processing machinery. Some of these techniques have been proposed as alternatives to CRISPR-based technologies, where the exogenous gene-editing machinery needs to be delivered and expressed in the human cells to generate permanent (DNA) changes with unknown consequences. Here, we review the current FDA-approved antisense MoA (emphasizing some enabling technologies that contributed to their success) and three novel modalities based on post-transcriptional RNA modifications with therapeutic potential, including ADAR (Adenosine deaminases acting on RNA)-mediated RNA editing, targeted pseudouridylation, and 2′-O-methylation.
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60
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Non-Immunotherapy Application of LNP-mRNA: Maximizing Efficacy and Safety. Biomedicines 2021; 9:biomedicines9050530. [PMID: 34068715 PMCID: PMC8151051 DOI: 10.3390/biomedicines9050530] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Lipid nanoparticle (LNP) formulated messenger RNA-based (LNP-mRNA) vaccines came into the spotlight as the first vaccines against SARS-CoV-2 virus to be applied worldwide. Long-known benefits of mRNA-based technologies consisting of relatively simple and fast engineering of mRNA encoding for antigens and proteins of interest, no genomic integration, and fast and efficient manufacturing process compared with other biologics have been verified, thus establishing a basis for a broad range of applications. The intrinsic immunogenicity of LNP formulated in vitro transcribed (IVT) mRNA is beneficial to the LNP-mRNA vaccines. However, avoiding immune activation is critical for therapeutic applications of LNP-mRNA for protein replacement where targeted mRNA expression and repetitive administration of high doses for a lifetime are required. This review summarizes our current understanding of immune activation induced by mRNA, IVT byproducts, and LNP. It gives a comprehensive overview of the present status of preclinical and clinical studies in which LNP-mRNA is used for protein replacement and treatment of rare diseases with an emphasis on safety. Moreover, the review outlines innovations and strategies to advance pharmacology and safety of LNP-mRNA for non-immunotherapy applications.
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61
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Sinnamon JR, Kim SY, Fisk JR, Song Z, Nakai H, Jeng S, McWeeney SK, Mandel G. In Vivo Repair of a Protein Underlying a Neurological Disorder by Programmable RNA Editing. Cell Rep 2021; 32:107878. [PMID: 32668243 PMCID: PMC7449137 DOI: 10.1016/j.celrep.2020.107878] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/08/2020] [Accepted: 06/16/2020] [Indexed: 02/07/2023] Open
Abstract
Programmable RNA editing is gaining momentum as an approach to repair mutations, but its efficiency in repairing endogenous mutant RNA in complex tissue is unknown. Here we apply this approach to the brain and successfully repair a guanosine-to-adenosine mutation in methyl CpG binding protein 2 RNA that causes the neurodevelopmental disease Rett syndrome. Repair is mediated by hippocampal injections of juvenile Mecp2317G>A mice with an adeno-associated virus expressing the hyperactive catalytic domain of adenosine deaminase acting on RNA 2 and Mecp2 guide. After 1 month, 50% of Mecp2 RNA is recoded in three different hippocampal neuronal populations. MeCP2 protein localization to heterochromatin is restored in neurons to 50% of wild-type levels. Whole-transcriptome RNA analysis of one neuronal population indicates that the majority of off-target editing sites exhibit rates of 30% or less. This study demonstrates that programmable RNA editing can be utilized to repair mutations in mouse models of neurological disease. Sinnamon et al. show that the Mecp2 guide-targeted “editase,” introduced by an adeno-associated virus into the hippocampus of a Rett syndrome mouse model, repairs a large fraction of pathological Mecp2G>A RNA. MeCP2 function, visualized by chromatin association in neurons, is repaired to similar levels. The results point toward a potential therapy for Rett syndrome.
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Affiliation(s)
- John R Sinnamon
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Susan Y Kim
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Jenna R Fisk
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Zhen Song
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97239, USA
| | - Hiroyuki Nakai
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97239, USA
| | - Sophia Jeng
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Knight Cancer Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Shannon K McWeeney
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Knight Cancer Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Gail Mandel
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA.
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62
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Srinivasan S, Torres AG, Ribas de Pouplana L. Inosine in Biology and Disease. Genes (Basel) 2021; 12:600. [PMID: 33921764 PMCID: PMC8072771 DOI: 10.3390/genes12040600] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 02/06/2023] Open
Abstract
The nucleoside inosine plays an important role in purine biosynthesis, gene translation, and modulation of the fate of RNAs. The editing of adenosine to inosine is a widespread post-transcriptional modification in transfer RNAs (tRNAs) and messenger RNAs (mRNAs). At the wobble position of tRNA anticodons, inosine profoundly modifies codon recognition, while in mRNA, inosines can modify the sequence of the translated polypeptide or modulate the stability, localization, and splicing of transcripts. Inosine is also found in non-coding and exogenous RNAs, where it plays key structural and functional roles. In addition, molecular inosine is an important secondary metabolite in purine metabolism that also acts as a molecular messenger in cell signaling pathways. Here, we review the functional roles of inosine in biology and their connections to human health.
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Affiliation(s)
- Sundaramoorthy Srinivasan
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
| | - Adrian Gabriel Torres
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
| | - Lluís Ribas de Pouplana
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
- Catalan Institution for Research and Advanced Studies, 08010 Barcelona, Catalonia, Spain
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63
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Quin J, Sedmík J, Vukić D, Khan A, Keegan LP, O'Connell MA. ADAR RNA Modifications, the Epitranscriptome and Innate Immunity. Trends Biochem Sci 2021; 46:758-771. [PMID: 33736931 DOI: 10.1016/j.tibs.2021.02.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/28/2021] [Accepted: 02/18/2021] [Indexed: 12/22/2022]
Abstract
Modified bases act as marks on cellular RNAs so that they can be distinguished from foreign RNAs, reducing innate immune responses to endogenous RNA. In humans, mutations giving reduced levels of one base modification, adenosine-to-inosine deamination, cause a viral infection mimic syndrome, a congenital encephalitis with aberrant interferon induction. These Aicardi-Goutières syndrome 6 mutations affect adenosine deaminase acting on RNA 1 (ADAR1), which generates inosines in endogenous double-stranded (ds)RNA. The inosine base alters dsRNA structure to prevent aberrant activation of antiviral cytosolic helicase RIG-I-like receptors. We review how effects of inosines, ADARs, and other modified bases have been shown to be important in innate immunity and cancer.
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Affiliation(s)
- Jaclyn Quin
- Central European Institute of Technology, Masaryk University Brno, Kamenice 753/5, Pavilion A35, Brno CZ-62500, Czech Republic
| | - Jiří Sedmík
- Central European Institute of Technology, Masaryk University Brno, Kamenice 753/5, Pavilion A35, Brno CZ-62500, Czech Republic
| | - Dragana Vukić
- Central European Institute of Technology, Masaryk University Brno, Kamenice 753/5, Pavilion A35, Brno CZ-62500, Czech Republic
| | - Anzer Khan
- Central European Institute of Technology, Masaryk University Brno, Kamenice 753/5, Pavilion A35, Brno CZ-62500, Czech Republic
| | - Liam P Keegan
- Central European Institute of Technology, Masaryk University Brno, Kamenice 753/5, Pavilion A35, Brno CZ-62500, Czech Republic.
| | - Mary A O'Connell
- Central European Institute of Technology, Masaryk University Brno, Kamenice 753/5, Pavilion A35, Brno CZ-62500, Czech Republic.
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64
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Abstract
RNA editing is an RNA modification that alters the RNA sequence relative to its genomic blueprint. The most common type of RNA editing is A-to-I editing by double-stranded RNA-specific adenosine deaminase (ADAR) enzymes. Editing of a protein-coding region within the RNA molecule may result in non-synonymous substitutions, leading to a modified protein product. These editing sites, also known as "recoding" sites, contribute to the complexity and diversification of the proteome. Recent computational transcriptomic studies have identified thousands of recoding sites in multiple species, many of which are conserved within (but not usually across) lineages and have functional and evolutionary importance. In this chapter we describe the recoding phenomenon across species, consider its potential utility for diversity and adaptation, and discuss its evolution.
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65
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Kurkowiak M, Arcimowicz Ł, Chruściel E, Urban-Wójciuk Z, Papak I, Keegan L, O'Connell M, Kowalski J, Hupp T, Marek-Trzonkowska N. The effects of RNA editing in cancer tissue at different stages in carcinogenesis. RNA Biol 2021; 18:1524-1539. [PMID: 33593231 PMCID: PMC8582992 DOI: 10.1080/15476286.2021.1877024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
RNA editing is one of the most prevalent and abundant forms of post-transcriptional RNA modification observed in normal physiological processes and often aberrant in diseases including cancer. RNA editing changes the sequences of mRNAs, making them different from the source DNA sequence. Edited mRNAs can produce editing-recoded protein isoforms that are functionally different from the corresponding genome-encoded protein isoforms. The major type of RNA editing in mammals occurs by enzymatic deamination of adenosine to inosine (A-to-I) within double-stranded RNAs (dsRNAs) or hairpins in pre-mRNA transcripts. Enzymes that catalyse these processes belong to the adenosine deaminase acting on RNA (ADAR) family. The vast majority of knowledge on the RNA editing landscape relevant to human disease has been acquired using in vitro cancer cell culture models. The limitation of such in vitro models, however, is that the physiological or disease relevance of results obtained is not necessarily obvious. In this review we focus on discussing in vivo occurring RNA editing events that have been identified in human cancer tissue using samples surgically resected or clinically retrieved from patients. We discuss how RNA editing events occurring in tumours in vivo can identify pathological signalling mechanisms relevant to human cancer physiology which is linked to the different stages of cancer progression including initiation, promotion, survival, proliferation, immune escape and metastasis.
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Affiliation(s)
- Małgorzata Kurkowiak
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland
| | - Łukasz Arcimowicz
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland
| | - Elżbieta Chruściel
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland
| | - Zuzanna Urban-Wójciuk
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland
| | - Ines Papak
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland
| | - Liam Keegan
- CEITEC Masaryk University, Brno, CZ, Czech Republic
| | | | - Jacek Kowalski
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland.,Department of Pathomorphology, Medical University of Gdańsk, Gdańsk, Poland
| | - Ted Hupp
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland.,University of Edinburgh, Edinburgh Cancer Research Centre, Edinburgh, Scotland, UK
| | - Natalia Marek-Trzonkowska
- International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Gdańsk, Poland.,Laboratory of Immunoregulation and Cellular Therapies, Department of Family Medicine, Medical University of Gdańsk, Gdańsk, Poland
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66
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Loss of Cnot6l Impairs Inosine RNA Modifications in Mouse Oocytes. Int J Mol Sci 2021; 22:ijms22031191. [PMID: 33530472 PMCID: PMC7865253 DOI: 10.3390/ijms22031191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/19/2021] [Accepted: 01/22/2021] [Indexed: 01/28/2023] Open
Abstract
Mammalian oocytes must degrade maternal transcripts through a process called translational mRNA decay, in which maternal mRNA undergoes translational activation, followed by deadenylation and mRNA decay. Once a transcript is translationally activated, it becomes deadenylated by the CCR4-NOT complex. Knockout of CCR4-NOT Transcription Complex Subunit 6 Like (Cnot6l), a deadenylase within the CCR4-NOT complex, results in mRNA decay defects during metaphase I (MI) entry. Knockout of B-cell translocation gene-4 (Btg4), an adaptor protein of the CCR4-NOT complex, results in mRNA decay defects following fertilization. Therefore, mechanisms controlling mRNA turnover have significant impacts on oocyte competence and early embryonic development. Post-transcriptional inosine RNA modifications can impact mRNA stability, possibly through a translation mechanism. Here, we assessed inosine RNA modifications in oocytes, eggs, and embryos from Cnot6l-/- and Btg4-/- mice, which display stabilization of mRNA and over-translation of the stabilized transcripts. If inosine modifications have a role in modulating RNA stability, we hypothesize that in these mutant backgrounds, we would observe changes or a disruption in inosine mRNA modifications. To test this, we used a computational approach to identify inosine RNA modifications in total and polysomal RNA-seq data during meiotic maturation (GV, MI, and MII stages). We observed pronounced depletion of inosine mRNA modifications in samples from Cnot6l-/-, but not in Btg4-/- mice. Additionally, analysis of ribosome-associated RNA revealed clearance of inosine modified mRNA. These observations suggest a novel mechanism of mRNA clearance during oocyte maturation, in which inosine-containing transcripts decay in an independent, but parallel mechanism to CCR4-NOT deadenylation.
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67
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Duan Y, Dou S, Porath HT, Huang J, Eisenberg E, Lu J. A-to-I RNA editing in honeybees shows signals of adaptation and convergent evolution. iScience 2021; 24:101983. [PMID: 33458624 PMCID: PMC7797907 DOI: 10.1016/j.isci.2020.101983] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/18/2020] [Accepted: 12/17/2020] [Indexed: 12/27/2022] Open
Abstract
Social insects exhibit extensive phenotypic diversities among the genetically similar individuals, suggesting a role for the epigenetic regulations beyond the genome level. The ADAR-mediated adenosine-to-inosine (A-to-I) RNA editing, an evolutionarily conserved mechanism, facilitates adaptive evolution by expanding proteomic diversities. Here, we characterize the A-to-I RNA editome of honeybees (Apis mellifera), identifying 407 high-confidence A-to-I editing sites. Editing is most abundant in the heads and shows signatures for positive selection. Editing behavior differs between foragers and nurses, suggesting a role for editing in caste differentiation. Although only five sites are conserved between bees and flies, an unexpectedly large number of genes exhibit editing in both species, albeit at different locations, including the nonsynonymous auto-editing of Adar. This convergent evolution, where the same target genes independently acquire recoding events in distant diverged clades, together with the signals of adaptation observed in honeybees alone, further supports the notion of recoding being adaptive. Nonsynonymous editing sites in honeybees were under positive selection Differential editing may contribute to the phenotypic diversity between sub-castes Target genes acquire editing in different clades, suggesting convergent evolution
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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, 100871, China.,Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Shengqian Dou
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, 100871, China
| | - Hagit T Porath
- The Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat-Gan 52900, Israel
| | - Jiaxing Huang
- Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture and Rural Affairs, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, 100093, China
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Jian Lu
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, School of Life Sciences, Peking University, Beijing, 100871, China
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68
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Abstract
The mRNA epitranscriptome imparts diversity to gene expression by installing chemical modifications. Advances in detection methods have identified chemical modifications in eukaryotic, bacterial, and viral messenger RNAs (mRNAs). The biological functions of modifications in mRNAs still remain to be understood. Chemical modifications are introduced in synthetic mRNAs meant for therapeutic applications to maximize expression from the synthetic mRNAs and to evade the host immune response. This overview provides a background of chemical modifications found in mRNAs, with an emphasis on pseudouridine and its known effects on the mRNA life cycle, its potential applications in synthetic mRNA, and the methods used to assess its effects on mRNA translation.
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Affiliation(s)
- Bijoyita Roy
- RNA and Genome Editing, New England Biolabs Inc, Ipswich, MA, USA.
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69
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Anreiter I, Mir Q, Simpson JT, Janga SC, Soller M. New Twists in Detecting mRNA Modification Dynamics. Trends Biotechnol 2021; 39:72-89. [PMID: 32620324 PMCID: PMC7326690 DOI: 10.1016/j.tibtech.2020.06.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 12/28/2022]
Abstract
Modified nucleotides in mRNA are an essential addition to the standard genetic code of four nucleotides in animals, plants, and their viruses. The emerging field of epitranscriptomics examines nucleotide modifications in mRNA and their impact on gene expression. The low abundance of nucleotide modifications and technical limitations, however, have hampered systematic analysis of their occurrence and functions. Selective chemical and immunological identification of modified nucleotides has revealed global candidate topology maps for many modifications in mRNA, but further technical advances to increase confidence will be necessary. Single-molecule sequencing introduced by Oxford Nanopore now promises to overcome such limitations, and we summarize current progress with a particular focus on the bioinformatic challenges of this novel sequencing technology.
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Affiliation(s)
- Ina Anreiter
- Ontario Institute for Cancer Research, Toronto, ON M5G 0A3, Canada; Department of Computer Science, University of Toronto, Toronto, ON M5S 2E4, Canada
| | - Quoseena Mir
- Department of BioHealth Informatics, School of Informatics and Computing, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Jared T Simpson
- Ontario Institute for Cancer Research, Toronto, ON M5G 0A3, Canada; Department of Computer Science, University of Toronto, Toronto, ON M5S 2E4, Canada
| | - Sarath C Janga
- Department of BioHealth Informatics, School of Informatics and Computing, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; Department of Medical and Molecular Genetics, Medical Research and Library Building, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Center for Computational Biology and Bioinformatics, 5021 Health Information and Translational Sciences, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Matthias Soller
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
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70
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Erdmann EA, Mahapatra A, Mukherjee P, Yang B, Hundley HA. To protect and modify double-stranded RNA - the critical roles of ADARs in development, immunity and oncogenesis. Crit Rev Biochem Mol Biol 2020; 56:54-87. [PMID: 33356612 DOI: 10.1080/10409238.2020.1856768] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adenosine deaminases that act on RNA (ADARs) are present in all animals and function to both bind double-stranded RNA (dsRNA) and catalyze the deamination of adenosine (A) to inosine (I). As inosine is a biological mimic of guanosine, deamination by ADARs changes the genetic information in the RNA sequence and is commonly referred to as RNA editing. Millions of A-to-I editing events have been reported for metazoan transcriptomes, indicating that RNA editing is a widespread mechanism used to generate molecular and phenotypic diversity. Loss of ADARs results in lethality in mice and behavioral phenotypes in worm and fly model systems. Furthermore, alterations in RNA editing occur in over 35 human pathologies, including several neurological disorders, metabolic diseases, and cancers. In this review, a basic introduction to ADAR structure and target recognition will be provided before summarizing how ADARs affect the fate of cellular RNAs and how researchers are using this knowledge to engineer ADARs for personalized medicine. In addition, we will highlight the important roles of ADARs and RNA editing in innate immunity and cancer biology.
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Affiliation(s)
- Emily A Erdmann
- Department of Biology, Indiana University, Bloomington, IN, USA
| | | | - Priyanka Mukherjee
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
| | - Boyoon Yang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
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71
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Genome-Wide Characterization of RNA Editing Sites in Primary Gastric Adenocarcinoma through RNA-seq Data Analysis. Int J Genomics 2020; 2020:6493963. [PMID: 33415135 PMCID: PMC7768588 DOI: 10.1155/2020/6493963] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/28/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022] Open
Abstract
RNA editing is a posttranscriptional nucleotide modification in humans. Of the various types of RNA editing, the adenosine to inosine substitution is the most widespread in higher eukaryotes, which is mediated by the ADAR family enzymes. Inosine is recognized by the biological machinery as guanosine; therefore, editing could have substantial functional effects throughout the genome. RNA editing could contribute to cancer either by exclusive editing of tumor suppressor/promoting genes or by introducing transcriptomic diversity to promote cancer progression. Here, we provided a comprehensive overview of the RNA editing sites in gastric adenocarcinoma and highlighted some of their possible contributions to gastric cancer. RNA-seq data corresponding to 8 gastric adenocarcinoma and their paired nontumor counterparts were retrieved from the GEO database. After preprocessing and variant calling steps, a stringent filtering pipeline was employed to distinguish potential RNA editing sites from SNPs. The identified potential editing sites were annotated and compared with those in the DARNED database. Totally, 12362 high-confidence adenosine to inosine RNA editing sites were detected across all samples. Of these, 12105 and 257 were known and novel editing events, respectively. These editing sites were unevenly distributed across genomic regions, and nearly half of them were located in 3′UTR. Our results revealed that 4868 editing sites were common in both normal and cancer tissues. From the remaining sites, 3985 and 3509 were exclusive to normal and cancer tissues, respectively. Further analysis revealed a significant number of differentially edited events among these sites, which were located in protein coding genes and microRNAs. Given the distinct pattern of RNA editing in gastric adenocarcinoma and adjacent normal tissue, edited sites have the potential to serve as the diagnostic biomarkers and therapeutic targets in gastric cancer.
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72
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Rajendren S, Dhakal A, Vadlamani P, Townsend J, Deffit SN, Hundley HA. Profiling neural editomes reveals a molecular mechanism to regulate RNA editing during development. Genome Res 2020; 31:27-39. [PMID: 33355311 PMCID: PMC7849389 DOI: 10.1101/gr.267575.120] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 11/18/2020] [Indexed: 12/18/2022]
Abstract
Adenosine (A) to inosine (I) RNA editing contributes to transcript diversity and modulates gene expression in a dynamic, cell type–specific manner. During mammalian brain development, editing of specific adenosines increases, whereas the expression of A-to-I editing enzymes remains unchanged, suggesting molecular mechanisms that mediate spatiotemporal regulation of RNA editing exist. Herein, by using a combination of biochemical and genomic approaches, we uncover a molecular mechanism that regulates RNA editing in a neural- and development-specific manner. Comparing editomes during development led to the identification of neural transcripts that were edited only in one life stage. The stage-specific editing is largely regulated by differential gene expression during neural development. Proper expression of nearly one-third of the neurodevelopmentally regulated genes is dependent on adr-2, the sole A-to-I editing enzyme in C. elegans. However, we also identified a subset of neural transcripts that are edited and expressed throughout development. Despite a neural-specific down-regulation of adr-2 during development, the majority of these sites show increased editing in adult neural cells. Biochemical data suggest that ADR-1, a deaminase-deficient member of the adenosine deaminase acting on RNA (ADAR) family, is competing with ADR-2 for binding to specific transcripts early in development. Our data suggest a model in which during neural development, ADR-2 levels overcome ADR-1 repression, resulting in increased ADR-2 binding and editing of specific transcripts. Together, our findings reveal tissue- and development-specific regulation of RNA editing and identify a molecular mechanism that regulates ADAR substrate recognition and editing efficiency.
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Affiliation(s)
- Suba Rajendren
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Alfa Dhakal
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, Indiana 47405, USA
| | - Pranathi Vadlamani
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, Indiana 47405, USA
| | - Jack Townsend
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, Indiana 47405, USA
| | - Sarah N Deffit
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, Indiana 47405, USA
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, Indiana 47405, USA
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73
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Skinner A, Yang C, Hincks K, Wang H, Resendiz MJE. Experimental and theoretical rationalization for the base pairing abilities of inosine, guanosine, adenosine, and their corresponding 8-oxo-7,8-dihydropurine, and 8-bromopurine analogues within A-form duplexes of RNA. Biopolymers 2020; 111:e23410. [PMID: 33216981 PMCID: PMC7780609 DOI: 10.1002/bip.23410] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 10/30/2020] [Accepted: 11/09/2020] [Indexed: 12/13/2022]
Abstract
Inosine is an important RNA modification, furthermore RNA oxidation has gained interest due, in part, to its potential role in the development/progression of disease as well as on its impact on RNA structure and function. In this report we established the base pairing abilities of purine nucleobases G, I, A, as well as their corresponding, 8-oxo-7,8-dihydropurine (common products of oxidation at the C8-position of purines), and 8-bromopurine (as probes to explore conformational changes), derivatives, namely 8-oxoG, 8-oxoI, 8-oxoA, 8-BrG, and 8-BrI. Dodecamers of RNA were obtained using standard phosphoramidite chemistry via solid-phase synthesis, and used as models to establish the impact that each of these nucleobases have on the thermal stability of duplexes, when base pairing to canonical and noncanonical nucleobases. Thermal stabilities were obtained from thermal denaturation transition (Tm ) measurements, via circular dichroism (CD). The results were then rationalized using models of base pairs between two monomers, via density functional theory (DFT), that allowed us to better understand potential contributions from H-bonding patterns arising from distinct conformations. Overall, some of the important results indicate that: (a) an anti-I:syn-A base pair provides thermal stability, due to the absence of the exocyclic amine; (b) 8-oxoG base pairs like U, and does not induce destabilization within the duplex when compared to the pyrimidine ring; (c) a U:G wobble-pair is only stabilized by G; and (d) 8-oxoA displays an inherited base pairing promiscuity in this sequence context. Gaining a better understanding of how this oxidatively generated lesions potentially base pair with other nucleobases will be useful to predict various biological outcomes, as well as in the design of biomaterials and/or nucleotide derivatives with biological potential.
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Affiliation(s)
- Austin Skinner
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
| | - Chou‐Hsun Yang
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
| | - Kazuki Hincks
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
| | - Haobin Wang
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
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74
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Brachova P, Alvarez NS, Hong X, Gunewardena S, Vincent KA, Latham KE, Christenson LK. Inosine RNA modifications are enriched at the codon wobble position in mouse oocytes and eggs†. Biol Reprod 2020; 101:938-949. [PMID: 31346607 DOI: 10.1093/biolre/ioz130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/07/2019] [Accepted: 07/12/2019] [Indexed: 12/30/2022] Open
Abstract
Mammalian oocytes and eggs are transcriptionally quiescent and depend on post-transcriptional mechanisms for proper maturation. Post-transcriptional mRNA modifications comprise an important regulatory mechanism that can alter protein and miRNA recognition sites, splicing, stability, secondary structure, and protein coding. We discovered that fully grown mouse germinal vesicle oocytes and metaphase II eggs display abundant inosine mRNA modifications compared to growing oocytes from postnatal day 12 oocytes. These inosines were enriched in mRNA protein coding regions (CDS) and specifically located at the third codon base, or wobble position. Inosines, observed at lower frequencies in CDS of somatic tissues, were similarly enriched at the codon wobble position. In oocytes and eggs, inosine modifications lead primarily to synonymous changes in mRNA transcripts. Inosines may ultimately affect maternal mRNA stability by changing codon usage, thereby altering translational efficiency and translationally coupled mRNA degradation. These important observations advance our understanding of post-transcriptional mechanisms contributing to mammalian oocyte maturation.
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Affiliation(s)
- Pavla Brachova
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Nehemiah S Alvarez
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA.,De Novo Genomics, Kansas City, KS, USA
| | - Xiaoman Hong
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Sumedha Gunewardena
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Kailey A Vincent
- Department of Animal Science and Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Keith E Latham
- Department of Animal Science and Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Lane K Christenson
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
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75
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Translesion synthesis by AMV, HIV, and MMLVreverse transcriptases using RNA templates containing inosine, guanosine, and their 8-oxo-7,8-dihydropurine derivatives. PLoS One 2020; 15:e0235102. [PMID: 32857764 PMCID: PMC7455023 DOI: 10.1371/journal.pone.0235102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 08/07/2020] [Indexed: 12/31/2022] Open
Abstract
Inosine is ubiquitous and essential in many biological processes, including RNA-editing. In addition, oxidative stress on RNA has been a topic of increasing interest due, in part, to its potential role in the development/progression of disease. In this work we probed the ability of three reverse transcriptases (RTs) to catalyze the synthesis of cDNA in the presence of RNA templates containing inosine (I), 8-oxo-7,8-dihydroinosine (8oxo-I), guanosine (G), or 8-oxo-7,8-dihydroguanosine (8-oxoG), and explored the impact that these purine derivatives have as a function of position. To this end, we used 29-mers of RNA (as template) containing the modifications at position-18 and reverse transcribed DNA using 17-mers, 18-mers, or 19-mers (as primers). Generally reactivity of the viral RTs, AMV / HIV / MMLV, towards cDNA synthesis was similar for templates containing G or I as well as for those with 8-oxoG or 8-oxoI. Notable differences are: 1) the use of 18-mers of DNA (to explore cDNA synthesis past the lesion/modification) led to inhibition of DNA elongation in cases where a G:dA wobble pair was present, while the presence of I, 8-oxoI, or 8-oxoG led to full synthesis of the corresponding cDNA, with the latter two displaying a more efficient process; 2) HIV RT is more sensitive to modified base pairs in the vicinity of cDNA synthesis; and 3) the presence of a modification two positions away from transcription initiation has an adverse impact on the overall process. Steady-state kinetics were established using AMV RT to determine substrate specificities towards canonical dNTPs (N = G, C, T, A). Overall we found evidence that RNA templates containing inosine are likely to incorporate dC > dT > > dA, where reactivity in the presence of dA was found to be pH dependent (process abolished at pH 7.3); and that the absence of the C2-exocyclic amine, as displayed with templates containing 8-oxoI, leads to increased selectivity towards incorporation of dA over dC. The data will be useful in assessing the impact that the presence of inosine and/or oxidatively generated lesions have on viral processes and adds to previous reports where I codes exclusively like G. Similar results were obtained upon comparison of AMV and MMLV RTs.
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76
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Nakahama T, Kawahara Y. Adenosine-to-inosine RNA editing in the immune system: friend or foe? Cell Mol Life Sci 2020; 77:2931-2948. [PMID: 31996954 PMCID: PMC11104962 DOI: 10.1007/s00018-020-03466-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/27/2019] [Accepted: 01/14/2020] [Indexed: 12/19/2022]
Abstract
Our body expresses sensors to detect pathogens through the recognition of expressed molecules, including nucleic acids, lipids, and proteins, while immune tolerance prevents an overreaction with self and the development of autoimmune disease. Adenosine (A)-to-inosine (I) RNA editing, catalyzed by adenosine deaminases acting on RNA (ADARs), is a post-transcriptional modification that can potentially occur at over 100 million sites in the human genome, mainly in Alu repetitive elements that preferentially form a double-stranded RNA (dsRNA) structure. A-to-I conversion within dsRNA, which may induce a structural change, is required to escape from the host immune system, given that endogenous dsRNAs transcribed from Alu repetitive elements are potentially recognized by melanoma differentiation-associated protein 5 (MDA5) as non-self. Of note, loss-of-function mutations in the ADAR1 gene cause Aicardi-Goutières syndrome, a congenital autoimmune disease characterized by encephalopathy and a type I interferon (IFN) signature. However, the loss of ADAR1 in cancer cells with an IFN signature induces lethality via the activation of protein kinase R in addition to MDA5. This makes cells more sensitive to immunotherapy, highlighting the opposing immune status of autoimmune diseases (overreaction) and cancer (tolerance). In this review, we provide an overview of insights into two opposing aspects of RNA editing that functions as a modulator of the immune system in autoimmune diseases and cancer.
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Affiliation(s)
- Taisuke Nakahama
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Yukio Kawahara
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan.
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77
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Kapoor U, Licht K, Amman F, Jakobi T, Martin D, Dieterich C, Jantsch MF. ADAR-deficiency perturbs the global splicing landscape in mouse tissues. Genome Res 2020; 30:1107-1118. [PMID: 32727871 PMCID: PMC7462079 DOI: 10.1101/gr.256933.119] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 07/10/2020] [Indexed: 02/06/2023]
Abstract
Adenosine-to-inosine RNA editing and pre-mRNA splicing largely occur cotranscriptionally and influence each other. Here, we use mice deficient in either one of the two editing enzymes ADAR (ADAR1) or ADARB1 (ADAR2) to determine the transcriptome-wide impact of RNA editing on splicing across different tissues. We find that ADAR has a 100× higher impact on splicing than ADARB1, although both enzymes target a similar number of substrates with a large common overlap. Consistently, differentially spliced regions frequently harbor ADAR editing sites. Moreover, catalytically dead ADAR also impacts splicing, demonstrating that RNA binding of ADAR affects splicing. In contrast, ADARB1 editing sites are found enriched 5′ of differentially spliced regions. Several of these ADARB1-mediated editing events change splice consensus sequences, therefore strongly influencing splicing of some mRNAs. A significant overlap between differentially edited and differentially spliced sites suggests evolutionary selection toward splicing being regulated by editing in a tissue-specific manner.
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Affiliation(s)
- Utkarsh Kapoor
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Konstantin Licht
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Fabian Amman
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria.,Institute of Theoretical Biochemistry, University of Vienna, A-1090 Vienna, Austria
| | - Tobias Jakobi
- Department of Internal Medicine III and Klaus Tschira Institute for Computational Cardiology, Section of Bioinformatics and Systems Cardiology, University Hospital, D-96120 Heidelberg, Germany
| | - David Martin
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Christoph Dieterich
- Department of Internal Medicine III and Klaus Tschira Institute for Computational Cardiology, Section of Bioinformatics and Systems Cardiology, University Hospital, D-96120 Heidelberg, Germany
| | - Michael F Jantsch
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
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78
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Jones JD, Monroe J, Koutmou KS. A molecular-level perspective on the frequency, distribution, and consequences of messenger RNA modifications. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1586. [PMID: 31960607 PMCID: PMC8243748 DOI: 10.1002/wrna.1586] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 12/21/2019] [Accepted: 01/04/2020] [Indexed: 01/16/2023]
Abstract
Cells use chemical modifications to alter the sterics, charge, and conformations of large biomolecules, modulating their biogenesis, function, and stability. Until recently post-transcriptional RNA modifications were thought to be largely limited to nonprotein coding RNA species. However, this dogma has rapidly transformed with the discovery of a host of modifications in protein coding messenger RNAs (mRNAs). Recent advancements in genome-wide sequencing technologies have enabled the identification of mRNA modifications as a potential new frontier in gene regulation-leading to the development of the epitranscriptome field. As a result, there has been a flurry of multiple groundbreaking discoveries, including new modifications, nucleoside modifying enzymes ("writers" and "erasers"), and RNA binding proteins that recognize chemical modifications ("readers"). These discoveries opened the door to understanding how post-transcriptional mRNA modifications can modulate the mRNA lifecycle, and established a link between the epitranscriptome and human health and disease. Despite a rapidly growing recognition of their importance, fundamental questions regarding the identity, prevalence, and functional consequences of mRNA modifications remain to be answered. Here, we highlight quantitative studies that characterize mRNA modification abundance, frequency, and interactions with cellular machinery. As the field progresses, we see a need for the further integration of quantitative and reductionist approaches to complement transcriptome wide studies in order to establish a molecular-level framework for understanding the consequences of mRNA chemical modifications on biological processes. This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry RNA Processing > RNA Editing and Modification.
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Affiliation(s)
- Joshua D. Jones
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Jeremy Monroe
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Kristin S. Koutmou
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan
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79
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Heraud-Farlow JE, Walkley CR. What do editors do? Understanding the physiological functions of A-to-I RNA editing by adenosine deaminase acting on RNAs. Open Biol 2020; 10:200085. [PMID: 32603639 PMCID: PMC7574547 DOI: 10.1098/rsob.200085] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Adenosine-to-inosine (A-to-I) editing is a post-transcriptional modification of RNA which changes its sequence, coding potential and secondary structure. Catalysed by the adenosine deaminase acting on RNA (ADAR) proteins, ADAR1 and ADAR2, A-to-I editing occurs at approximately 50 000-150 000 sites in mice and into the millions of sites in humans. The vast majority of A-to-I editing occurs in repetitive elements, accounting for the discrepancy in total numbers of sites between species. The species-conserved primary role of editing by ADAR1 in mammals is to suppress innate immune activation by unedited cell-derived endogenous RNA. In the absence of editing, inverted paired sequences, such as Alu elements, are thought to form stable double-stranded RNA (dsRNA) structures which trigger activation of dsRNA sensors, such as MDA5. A small subset of editing sites are within coding sequences and are evolutionarily conserved across metazoans. Editing by ADAR2 has been demonstrated to be physiologically important for recoding of neurotransmitter receptors in the brain. Furthermore, changes in RNA editing are associated with various pathological states, from the severe autoimmune disease Aicardi-Goutières syndrome, to various neurodevelopmental and psychiatric conditions and cancer. However, does detection of an editing site imply functional importance? Genetic studies in humans and genetically modified mouse models together with evolutionary genomics have begun to clarify the roles of A-to-I editing in vivo. Furthermore, recent developments suggest there may be the potential for distinct functions of editing during pathological conditions such as cancer.
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Affiliation(s)
- Jacki E Heraud-Farlow
- Cancer and RNA Laboratory, St Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia.,Department of Medicine, St Vincent's Hospital, Melbourne Medical School, University of Melbourne, Fitzroy, VIC 3065, Australia
| | - Carl R Walkley
- Cancer and RNA Laboratory, St Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia.,Department of Medicine, St Vincent's Hospital, Melbourne Medical School, University of Melbourne, Fitzroy, VIC 3065, Australia.,Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3000, Australia
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80
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Mathlin J, Le Pera L, Colombo T. A Census and Categorization Method of Epitranscriptomic Marks. Int J Mol Sci 2020; 21:ijms21134684. [PMID: 32630140 PMCID: PMC7370119 DOI: 10.3390/ijms21134684] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 06/26/2020] [Accepted: 06/27/2020] [Indexed: 12/21/2022] Open
Abstract
In the past few years, thorough investigation of chemical modifications operated in the cells on ribonucleic acid (RNA) molecules is gaining momentum. This new field of research has been dubbed “epitranscriptomics”, in analogy to best-known epigenomics, to stress the potential of ensembles of RNA modifications to constitute a post-transcriptional regulatory layer of gene expression orchestrated by writer, reader, and eraser RNA-binding proteins (RBPs). In fact, epitranscriptomics aims at identifying and characterizing all functionally relevant changes involving both non-substitutional chemical modifications and editing events made to the transcriptome. Indeed, several types of RNA modifications that impact gene expression have been reported so far in different species of cellular RNAs, including ribosomal RNAs, transfer RNAs, small nuclear RNAs, messenger RNAs, and long non-coding RNAs. Supporting functional relevance of this largely unknown regulatory mechanism, several human diseases have been associated directly to RNA modifications or to RBPs that may play as effectors of epitranscriptomic marks. However, an exhaustive epitranscriptome’s characterization, aimed to systematically classify all RNA modifications and clarify rules, actors, and outcomes of this promising regulatory code, is currently not available, mainly hampered by lack of suitable detecting technologies. This is an unfortunate limitation that, thanks to an unprecedented pace of technological advancements especially in the sequencing technology field, is likely to be overcome soon. Here, we review the current knowledge on epitranscriptomic marks and propose a categorization method based on the reference ribonucleotide and its rounds of modifications (“stages”) until reaching the given modified form. We believe that this classification scheme can be useful to coherently organize the expanding number of discovered RNA modifications.
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Affiliation(s)
- Julia Mathlin
- Department of Life Sciences and Medicine, University of Luxembourg, L-4367 Belvaux, Luxembourg
- Correspondence: (J.M.); (L.L.P.); Tel.: +39-06-4991-0556 (L.L.P.)
| | - Loredana Le Pera
- CNR-Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), 70126 Bari, Italy
- CNR-Institute of Molecular Biology and Pathology (IBPM), 00185 Rome, Italy;
- Correspondence: (J.M.); (L.L.P.); Tel.: +39-06-4991-0556 (L.L.P.)
| | - Teresa Colombo
- CNR-Institute of Molecular Biology and Pathology (IBPM), 00185 Rome, Italy;
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81
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Schaffer AA, Kopel E, Hendel A, Picardi E, Levanon E, Eisenberg E. The cell line A-to-I RNA editing catalogue. Nucleic Acids Res 2020; 48:5849-5858. [PMID: 32383740 PMCID: PMC7293008 DOI: 10.1093/nar/gkaa305] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/30/2020] [Accepted: 04/21/2020] [Indexed: 12/14/2022] Open
Abstract
Adenosine-to-inosine (A-to-I) RNA editing is a common post transcriptional modification. It has a critical role in protecting against false activation of innate immunity by endogenous double stranded RNAs and has been associated with various regulatory processes and diseases such as autoimmune and cardiovascular diseases as well as cancer. In addition, the endogenous A-to-I editing machinery has been recently harnessed for RNA engineering. The study of RNA editing in humans relies heavily on the usage of cell lines as an important and commonly-used research tool. In particular, manipulations of the editing enzymes and their targets are often developed using cell line platforms. However, RNA editing in cell lines behaves very differently than in normal and diseased tissues, and most cell lines exhibit low editing levels, requiring over-expression of the enzymes. Here, we explore the A-to-I RNA editing landscape across over 1000 human cell lines types and show that for almost every editing target of interest a suitable cell line that mimics normal tissue condition may be found. We provide CLAIRE, a searchable catalogue of RNA editing levels across cell lines available at http://srv00.recas.ba.infn.it/atlas/claire.html, to facilitate rational choice of appropriate cell lines for future work on A-to-I RNA editing.
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Affiliation(s)
- Amos A Schaffer
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Eli Kopel
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ayal Hendel
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ernesto Picardi
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, I-70126 Bari, Italy
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari “A. Moro”, I-70126 Bari, Italy
| | - Erez Y Levanon
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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82
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Bajad P, Ebner F, Amman F, Szabó B, Kapoor U, Manjali G, Hildebrandt A, Janisiw MP, Jantsch MF. An internal deletion of ADAR rescued by MAVS deficiency leads to a minute phenotype. Nucleic Acids Res 2020; 48:3286-3303. [PMID: 31956894 PMCID: PMC7102943 DOI: 10.1093/nar/gkaa025] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 12/27/2019] [Accepted: 01/16/2020] [Indexed: 12/22/2022] Open
Abstract
The RNA-editing protein ADAR is essential for early development in the mouse. Genetic evidence suggests that A to I editing marks endogenous RNAs as ‘self’. Today, different Adar knockout alleles have been generated that show a common phenotype of apoptosis, liver disintegration, elevated immune response and lethality at E12.5. All the Adar knockout alleles can be rescued by a concomitant deletion of the innate immunity genes Mavs or Ifih1 (MDA5), albeit to different extents. This suggests multiple functions of ADAR. We analyze AdarΔ7-9 mice that show a unique growth defect phenotype when rescued by Mavs. We show that AdarΔ7-9 can form a truncated, unstable, editing deficient protein that is mislocalized. Histological and hematologic analysis of these mice indicate multiple tissue- and hematopoietic defects. Gene expression profiling shows dysregulation of Rps3a1 and Rps3a3 in rescued AdarΔ7-9. Consistently, a distortion in 40S and 60S ribosome ratios is observed in liver cells. This dysregulation is also seen in AdarΔ2-13; Mavs−/− but not in AdarE861A/E861A; Ifih1−/− mice, suggesting editing-independent functions of ADAR in regulating expression levels of Rps3a1 and Rps3a3. In conclusion, our study demonstrates the importance of ADAR in post-natal development which cannot be compensated by ADARB1.
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Affiliation(s)
- Prajakta Bajad
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Florian Ebner
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Fabian Amman
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria.,Institute of Theoretical Biochemistry, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
| | - Brigitta Szabó
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Utkarsh Kapoor
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Greeshma Manjali
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Alwine Hildebrandt
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Michael P Janisiw
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
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83
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Shi H, Chai P, Jia R, Fan X. Novel insight into the regulatory roles of diverse RNA modifications: Re-defining the bridge between transcription and translation. Mol Cancer 2020; 19:78. [PMID: 32303268 PMCID: PMC7164178 DOI: 10.1186/s12943-020-01194-6] [Citation(s) in RCA: 129] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/27/2020] [Indexed: 12/31/2022] Open
Abstract
RNA modifications can be added or removed by a variety of enzymes that catalyse the necessary reactions, and these modifications play roles in essential molecular mechanisms. The prevalent modifications on mRNA include N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), 5-hydroxymethylcytosine (hm5C), pseudouridine (Ψ), inosine (I), uridine (U) and ribosemethylation (2’-O-Me). Most of these modifications contribute to pre-mRNA splicing, nuclear export, transcript stability and translation initiation in eukaryotic cells. By participating in various physiological processes, RNA modifications also have regulatory roles in the pathogenesis of tumour and non-tumour diseases. We discussed the physiological roles of RNA modifications and associated these roles with disease pathogenesis. Functioning as the bridge between transcription and translation, RNA modifications are vital for the progression of numerous diseases and can even regulate the fate of cancer cells.
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Affiliation(s)
- Hanhan Shi
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, 20025, P.R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, 20025, People's Republic of China
| | - Peiwei Chai
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, 20025, P.R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, 20025, People's Republic of China
| | - Renbing Jia
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, 20025, P.R. China. .,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, 20025, People's Republic of China.
| | - Xianqun Fan
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, 20025, P.R. China. .,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, 20025, People's Republic of China.
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84
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Tan TY, Sedmík J, Fitzgerald MP, Halevy RS, Keegan LP, Helbig I, Basel-Salmon L, Cohen L, Straussberg R, Chung WK, Helal M, Maroofian R, Houlden H, Juusola J, Sadedin S, Pais L, Howell KB, White SM, Christodoulou J, O'Connell MA. Bi-allelic ADARB1 Variants Associated with Microcephaly, Intellectual Disability, and Seizures. Am J Hum Genet 2020; 106:467-483. [PMID: 32220291 DOI: 10.1016/j.ajhg.2020.02.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 02/26/2020] [Indexed: 11/15/2022] Open
Abstract
The RNA editing enzyme ADAR2 is essential for the recoding of brain transcripts. Impaired ADAR2 editing leads to early-onset epilepsy and premature death in a mouse model. Here, we report bi-allelic variants in ADARB1, the gene encoding ADAR2, in four unrelated individuals with microcephaly, intellectual disability, and epilepsy. In one individual, a homozygous variant in one of the double-stranded RNA-binding domains (dsRBDs) was identified. In the others, variants were situated in or around the deaminase domain. To evaluate the effects of these variants on ADAR2 enzymatic activity, we performed in vitro assays with recombinant proteins in HEK293T cells and ex vivo assays with fibroblasts derived from one of the individuals. We demonstrate that these ADAR2 variants lead to reduced editing activity on a known ADAR2 substrate. We also demonstrate that one variant leads to changes in splicing of ADARB1 transcript isoforms. These findings reinforce the importance of RNA editing in brain development and introduce ADARB1 as a genetic etiology in individuals with intellectual disability, microcephaly, and epilepsy.
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Affiliation(s)
- Tiong Yang Tan
- Victorian Clinical Genetics Services, Melbourne 3052, Australia; Murdoch Children's Research Institute, Melbourne 3052, Australia; Department of Pediatrics, University of Melbourne, Melbourne 3052, Australia.
| | - Jiří Sedmík
- Central European Institute of Technology, Masaryk University, Kamenice 735/5, A35, Brno 62500, Czech Republic
| | - Mark P Fitzgerald
- Division of Neurology, Departments of Neurology and Pediatrics, The Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Rivka Sukenik Halevy
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petah Tikva 49100, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Liam P Keegan
- Central European Institute of Technology, Masaryk University, Kamenice 735/5, A35, Brno 62500, Czech Republic
| | - Ingo Helbig
- Division of Neurology, Departments of Neurology and Pediatrics, The Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Lina Basel-Salmon
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petah Tikva 49100, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Felsenstein Medical Research Center, Petah Tikva 49100, Israel
| | - Lior Cohen
- Pediatric Genetics Unit, Schneider Children's Medical Center of Israel, Petah Tikva 49100, Israel
| | - Rachel Straussberg
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Pediatric Neurology Unit, Schneider Children's Medical Center of Israel, Petah Tikva 49100, Israel
| | - Wendy K Chung
- Department of Pediatrics, Columbia University Medical Center, New York, NY 10032, USA
| | - Mayada Helal
- Department of Pediatrics, Columbia University Medical Center, New York, NY 10032, USA
| | - Reza Maroofian
- Department of Neuromuscular Disorders, University College London Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, University College London Queen Square Institute of Neurology, London WC1N 3BG, UK
| | | | - Simon Sadedin
- Victorian Clinical Genetics Services, Melbourne 3052, Australia; Murdoch Children's Research Institute, Melbourne 3052, Australia
| | - Lynn Pais
- Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Katherine B Howell
- Murdoch Children's Research Institute, Melbourne 3052, Australia; Department of Pediatrics, University of Melbourne, Melbourne 3052, Australia; Department of Neurology, Royal Children's Hospital, Parkville 3052, Australia
| | - Susan M White
- Victorian Clinical Genetics Services, Melbourne 3052, Australia; Murdoch Children's Research Institute, Melbourne 3052, Australia; Department of Pediatrics, University of Melbourne, Melbourne 3052, Australia
| | - John Christodoulou
- Victorian Clinical Genetics Services, Melbourne 3052, Australia; Murdoch Children's Research Institute, Melbourne 3052, Australia; Department of Pediatrics, University of Melbourne, Melbourne 3052, Australia
| | - Mary A O'Connell
- Central European Institute of Technology, Masaryk University, Kamenice 735/5, A35, Brno 62500, Czech Republic.
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85
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Huang H, Weng H, Deng X, Chen J. RNA Modifications in Cancer: Functions, Mechanisms, and Therapeutic Implications. ANNUAL REVIEW OF CANCER BIOLOGY-SERIES 2020. [DOI: 10.1146/annurev-cancerbio-030419-033357] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Over 170 chemical modifications have been identified in protein-coding and noncoding RNAs and shown to exhibit broad impacts on gene expression. Dysregulation of RNA modifications caused by aberrant expression of or mutations in RNA modifiers aberrantly reprograms the epitranscriptome and skews global gene expression, which in turn leads to tumorigenesis and drug resistance. Here we review current knowledge of the functions and underlying mechanisms of aberrant RNA modifications in human cancers, particularly several common RNA modifications, including N6-methyladenosine (m6A), A-to-I editing, pseudouridine (ψ), 5-methylcytosine (m5C), 5-hydroxymethylcytosine (hm5C), N1-methyladenosine (m1A), and N4-acetylcytidine (ac4C), providing insights into therapeutic implications of targeting RNA modifications and the associated machineries for cancer therapy.
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Affiliation(s)
- Huilin Huang
- Department of Systems Biology and The Gehr Family Center for Leukemia Research, The Beckman Research Institute of City of Hope, Monrovia, California 91010, USA
| | - Hengyou Weng
- Department of Systems Biology and The Gehr Family Center for Leukemia Research, The Beckman Research Institute of City of Hope, Monrovia, California 91010, USA
| | - Xiaolan Deng
- Department of Systems Biology and The Gehr Family Center for Leukemia Research, The Beckman Research Institute of City of Hope, Monrovia, California 91010, USA
| | - Jianjun Chen
- Department of Systems Biology and The Gehr Family Center for Leukemia Research, The Beckman Research Institute of City of Hope, Monrovia, California 91010, USA
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86
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Konen LM, Wright AL, Royle GA, Morris GP, Lau BK, Seow PW, Zinn R, Milham LT, Vaughan CW, Vissel B. A new mouse line with reduced GluA2 Q/R site RNA editing exhibits loss of dendritic spines, hippocampal CA1-neuron loss, learning and memory impairments and NMDA receptor-independent seizure vulnerability. Mol Brain 2020; 13:27. [PMID: 32102661 PMCID: PMC7045468 DOI: 10.1186/s13041-020-0545-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/05/2020] [Indexed: 11/18/2022] Open
Abstract
Calcium (Ca2+)-permeable AMPA receptors may, in certain circumstances, contribute to normal synaptic plasticity or to neurodegeneration. AMPA receptors are Ca2+-permeable if they lack the GluA2 subunit or if GluA2 is unedited at a single nucleic acid, known as the Q/R site. In this study, we examined mice engineered with a point mutation in the intronic editing complementary sequence (ECS) of the GluA2 gene, Gria2. Mice heterozygous for the ECS mutation (named GluA2+/ECS(G)) had a ~ 20% reduction in GluA2 RNA editing at the Q/R site. We conducted an initial phenotypic analysis of these mice, finding altered current-voltage relations (confirming expression of Ca2+-permeable AMPA receptors at the synapse). Anatomically, we observed a loss of hippocampal CA1 neurons, altered dendritic morphology and reductions in CA1 pyramidal cell spine density. Behaviourally, GluA2+/ECS(G) mice exhibited reduced motor coordination, and learning and memory impairments. Notably, the mice also exhibited both NMDA receptor-independent long-term potentiation (LTP) and vulnerability to NMDA receptor-independent seizures. These NMDA receptor-independent seizures were rescued by the Ca2+-permeable AMPA receptor antagonist IEM-1460. In summary, unedited GluA2(Q) may have the potential to drive NMDA receptor-independent processes in brain function and disease. Our study provides an initial characterisation of a new mouse model for studying the role of unedited GluA2(Q) in synaptic and dendritic spine plasticity in disorders where unedited GluA2(Q), synapse loss, neurodegeneration, behavioural impairments and/or seizures are observed, such as ischemia, seizures and epilepsy, Huntington’s disease, amyotrophic lateral sclerosis, astrocytoma, cocaine seeking behaviour and Alzheimer’s disease.
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Affiliation(s)
- Lyndsey M Konen
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Amanda L Wright
- Department of Biomedical Sciences, Faculty of Medicine & Health Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Gordon A Royle
- Middlemore Hospital, Counties Manukau DHB, Otahuhu, Auckland, 1062, New Zealand.,The University of Auckland, Faculty of Medical and Health Sciences, School of Medicine, Grafton, Auckland, 1023, New Zealand
| | - Gary P Morris
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Benjamin K Lau
- Kolling Institute of Medical Research, Royal North Shore Hospital, The University of Sydney, Sydney, 2065, Australia
| | - Patrick W Seow
- Kolling Institute of Medical Research, Royal North Shore Hospital, The University of Sydney, Sydney, 2065, Australia
| | - Raphael Zinn
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Luke T Milham
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Christopher W Vaughan
- Kolling Institute of Medical Research, Royal North Shore Hospital, The University of Sydney, Sydney, 2065, Australia
| | - Bryce Vissel
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia. .,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia.
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87
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Lundin E, Wu C, Widmark A, Behm M, Hjerling-Leffler J, Daniel C, Öhman M, Nilsson M. Spatiotemporal mapping of RNA editing in the developing mouse brain using in situ sequencing reveals regional and cell-type-specific regulation. BMC Biol 2020; 18:6. [PMID: 31937309 PMCID: PMC6961268 DOI: 10.1186/s12915-019-0736-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 12/23/2019] [Indexed: 01/01/2023] Open
Abstract
Background Adenosine-to-inosine (A-to-I) RNA editing is a process that contributes to the diversification of proteins that has been shown to be essential for neurotransmission and other neuronal functions. However, the spatiotemporal and diversification properties of RNA editing in the brain are largely unknown. Here, we applied in situ sequencing to distinguish between edited and unedited transcripts in distinct regions of the mouse brain at four developmental stages, and investigate the diversity of the RNA landscape. Results We analyzed RNA editing at codon-altering sites using in situ sequencing at single-cell resolution, in combination with the detection of individual ADAR enzymes and specific cell type marker transcripts. This approach revealed cell-type-specific regulation of RNA editing of a set of transcripts, and developmental and regional variation in editing levels for many of the targeted sites. We found increasing editing diversity throughout development, which arises through regional- and cell type-specific regulation of ADAR enzymes and target transcripts. Conclusions Our single-cell in situ sequencing method has proved useful to study the complex landscape of RNA editing and our results indicate that this complexity arises due to distinct mechanisms of regulating individual RNA editing sites, acting both regionally and in specific cell types. Electronic supplementary material The online version of this article (10.1186/s12915-019-0736-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elin Lundin
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-171 21, Solna, Sweden.
| | - Chenglin Wu
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-171 21, Solna, Sweden
| | - Albin Widmark
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Mikaela Behm
- German Cancer Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - Jens Hjerling-Leffler
- Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Chammiran Daniel
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Marie Öhman
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Mats Nilsson
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-171 21, Solna, Sweden.
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88
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Goncharov AO, Kliuchnikova AA, Nasaev SS, Moshkovskii SA. RNA Editing by ADAR Adenosine Deaminases: From Molecular Plasticity of Neural Proteins to the Mechanisms of Human Cancer. BIOCHEMISTRY (MOSCOW) 2019; 84:896-904. [PMID: 31522671 DOI: 10.1134/s0006297919080054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
RNA editing by adenosine deaminases of the ADAR family attracts a growing interest of researchers, both zoologists studying ecological and evolutionary plasticity of invertebrates and medical biochemists focusing on the mechanisms of cancer and other human diseases. These enzymes deaminate adenosine residues in the double-stranded (ds) regions of RNA with the formation of inosine. As a result, some RNAs change their three-dimensional structure and functions. Adenosine-to-inosine editing in the mRNA coding sequences may cause amino acid substitutions in the encoded proteins. Here, we reviewed current concepts on the functions of two active ADAR isoforms identified in mammals (including humans). The ADAR1 protein, which acts non-specifically on extended dsRNA regions, is capable of immunosuppression via inactivation of the dsRNA interactions with specific sensors inducing the cell immunity. Expression of a specific ADAR1 splicing variant is regulated by the type I interferons by the negative feedback mechanism. It was shown that immunosuppressing effects of ADAR1 facilitate progression of some types of cancer. On the other hand, changes in the amino acid sequences resulting from the mRNA editing by the ADAR enzymes can result in the formation of neoantigens that can activate the antitumor immunity. The ADAR2 isoform acts on RNA more selectively; its function is associated with the editing of mRNA coding regions and can lead to the amino acid substitutions, in particular, those essential for the proper functioning of some neurotransmitter receptors in the central nervous system.
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Affiliation(s)
- A O Goncharov
- Institute of Biomedical Chemistry, Moscow, 119121, Russia.
| | - A A Kliuchnikova
- Institute of Biomedical Chemistry, Moscow, 119121, Russia.,Pirogov Russian National Research Medical University, Moscow, 117997, Russia
| | - S S Nasaev
- Pirogov Russian National Research Medical University, Moscow, 117997, Russia
| | - S A Moshkovskii
- Institute of Biomedical Chemistry, Moscow, 119121, Russia. .,Pirogov Russian National Research Medical University, Moscow, 117997, Russia
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89
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Jain M, Jantsch MF, Licht K. The Editor's I on Disease Development. Trends Genet 2019; 35:903-913. [PMID: 31648814 DOI: 10.1016/j.tig.2019.09.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 12/12/2022]
Abstract
Adenosine-to-inosine (A-to-I) editing of RNA leads to deamination of adenosine to inosine. Inosine is interpreted as guanosine by the cellular machinery, thus altering the coding, folding, splicing, or transport of transcripts. A-to-I editing is tightly regulated. Altered editing has severe consequences for human health and can cause interferonopathies, neurological disorders, and cardiovascular disease, as well as impacting on cancer progression. ADAR1-mediated RNA editing plays an important role in antiviral immunity and is essential for distinguishing between endogenous and viral RNA, thereby preventing autoimmune disorders. Interestingly, A-to-I editing can be used not only to correct genomic mutations at the RNA level but also to modulate tumor antigenicity with large therapeutic potential. We highlight recent developments in the field, focusing on cancer and other human diseases.
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Affiliation(s)
- Mamta Jain
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria.
| | - Konstantin Licht
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
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90
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Stafforst T. Chemistry Helps to Bump Off-Target Edits Away. Cell Chem Biol 2019; 26:151-152. [PMID: 30794785 DOI: 10.1016/j.chembiol.2019.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Side-directed RNA editing is an emerging tool to manipulate genetic information. Unfortunately, most approaches suffer from off-target editing. In this issue of Cell Chemical Biology, Monteleone et al. (2019) present a clever strategy that improves specificity by combining a mutant editase with a compensating chemical modification in the guiding RNA.
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Affiliation(s)
- Thorsten Stafforst
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
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91
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Abstract
Chemical modifications of RNAs have long been established as key modulators of nonprotein-coding RNA structure and function in cells. There is a growing appreciation that messenger RNA (mRNA) sequences responsible for directing protein synthesis can also be posttranscriptionally modified. The enzymatic incorporation of mRNA modifications has many potential outcomes, including changing mRNA stability, protein recruitment, and translation. We tested how one of the most common modifications present in mRNA coding regions, pseudouridine (Ψ), impacts protein synthesis using a fully reconstituted bacterial translation system and human cells. Our work reveals that replacing a single uridine nucleotide with Ψ in an mRNA codon impedes amino acid addition and EF-Tu GTPase activation. A crystal structure of the Thermus thermophilus 70S ribosome with a tRNAPhe bound to a ΨUU codon in the A site supports these findings. We also find that the presence of Ψ can promote the low-level synthesis of multiple peptide products from a single mRNA sequence in the reconstituted translation system as well as human cells, and increases the rate of near-cognate Val-tRNAVal reacting on a ΨUU codon. The vast majority of Ψ moieties in mRNAs are found in coding regions, and our study suggests that one consequence of the ribosome encountering Ψ can be to modestly alter both translation speed and mRNA decoding.
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92
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Roth SH, Levanon EY, Eisenberg E. Genome-wide quantification of ADAR adenosine-to-inosine RNA editing activity. Nat Methods 2019; 16:1131-1138. [PMID: 31636457 DOI: 10.1038/s41592-019-0610-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 08/20/2019] [Indexed: 12/19/2022]
Abstract
Adenosine-to-inosine (A-to-I) RNA editing by the adenosine deaminase that acts on RNA (ADAR) enzymes is a common RNA modification, preventing false activation of the innate immune system by endogenous double-stranded RNAs. Methods for quantification of ADAR activity are sought after, due to an increasing interest in the role of ADARs in cancer and autoimmune disorders, as well as attempts to harness the ADAR enzymes for RNA engineering. Here, we present the Alu editing index (AEI), a robust and simple-to-use computational tool devised for this purpose. We describe its properties and demonstrate its superiority to current quantification methods of ADAR activity. The AEI is used to map global editing across a large dataset of healthy human samples and identify putative regulators of ADAR, as well as previously unknown factors affecting the observed Alu editing levels. These should be taken into account in future comparative studies of ADAR activity. The AEI tool is available at https://github.com/a2iEditing/RNAEditingIndexer.
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Affiliation(s)
- Shalom Hillel Roth
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Erez Y Levanon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 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.
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93
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Levitsky LI, Kliuchnikova AA, Kuznetsova KG, Karpov DS, Ivanov MV, Pyatnitskiy MA, Kalinina OV, Gorshkov MV, Moshkovskii SA. Adenosine-to-Inosine RNA Editing in Mouse and Human Brain Proteomes. Proteomics 2019; 19:e1900195. [PMID: 31576663 DOI: 10.1002/pmic.201900195] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 09/25/2019] [Indexed: 12/30/2022]
Abstract
Proteogenomics is based on the use of customized genome or RNA sequencing databases for interrogation of shotgun proteomics data in search for proteome-level evidence of genome variations or RNA editing. In this work, the products of adenosine-to-inosine RNA editing in human and murine brain proteomes are identified using publicly available brain proteome LC-MS/MS datasets and an RNA editome database compiled from several sources. After filtering of false-positive results, 20 and 37 sites of editing in proteins belonging to 14 and 32 genes are identified for murine and human brain proteomes, respectively. Eight sites of editing identified with high spectral counts overlapped between human and mouse brain samples. Some of these sites have been previously reported using orthogonal methods, such as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors, CYFIP2, coatomer alpha. Also, differential editing between neurons and microglia is demonstrated in this work for some of the proteins from primary murine brain cell cultures. Because many edited sites are still not characterized functionally at the protein level, the results provide a necessary background for their further analysis in normal and diseased cells and tissues using targeted proteomic approaches.
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Affiliation(s)
- Lev I Levitsky
- V. L. Talrose Institute for Energy Problems of Chemical Physics, N. N. Semenov Federal Research Center of Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Anna A Kliuchnikova
- Institute of Biomedical Chemistry, 10 Pogodinskaya st., Moscow, 119121, Russia.,Department of Biochemistry, Pirogov Russian National Research Medical University, 1 Ostrovityanova st., Moscow, 117997, Russia
| | - Ksenia G Kuznetsova
- Institute of Biomedical Chemistry, 10 Pogodinskaya st., Moscow, 119121, Russia
| | - Dmitry S Karpov
- Institute of Biomedical Chemistry, 10 Pogodinskaya st., Moscow, 119121, Russia.,Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Mark V Ivanov
- V. L. Talrose Institute for Energy Problems of Chemical Physics, N. N. Semenov Federal Research Center of Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Mikhail A Pyatnitskiy
- Institute of Biomedical Chemistry, 10 Pogodinskaya st., Moscow, 119121, Russia.,Onco Genotest LLC, Moscow, 125047, Russia.,Department of Technologies for Complex System Modelling, National Research University Higher School of Economics, Moscow, 101000, Russia
| | - Olga V Kalinina
- Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research, Saarbrücken, 66123, Germany.,Medical Faculty, Saarland University, Kirrberger Straße, Homburg, 66421, Germany
| | - Mikhail V Gorshkov
- V. L. Talrose Institute for Energy Problems of Chemical Physics, N. N. Semenov Federal Research Center of Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia.,Moscow Institute of Physics and Technology (State University), Dolgoprudny, 141700, Moscow Region, Russia
| | - Sergei A Moshkovskii
- Institute of Biomedical Chemistry, 10 Pogodinskaya st., Moscow, 119121, Russia.,Department of Biochemistry, Pirogov Russian National Research Medical University, 1 Ostrovityanova st., Moscow, 117997, Russia
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94
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Licht K, Kapoor U, Amman F, Picardi E, Martin D, Bajad P, Jantsch MF. A high resolution A-to-I editing map in the mouse identifies editing events controlled by pre-mRNA splicing. Genome Res 2019; 29:1453-1463. [PMID: 31427386 PMCID: PMC6724681 DOI: 10.1101/gr.242636.118] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 07/25/2019] [Indexed: 11/25/2022]
Abstract
Pre-mRNA-splicing and adenosine to inosine (A-to-I) RNA-editing occur mostly cotranscriptionally. During A-to-I editing, a genomically encoded adenosine is deaminated to inosine by adenosine deaminases acting on RNA (ADARs). Editing-competent stems are frequently formed between exons and introns. Consistently, studies using reporter assays have shown that splicing efficiency can affect editing levels. Here, we use Nascent-seq and identify ∼90,000 novel A-to-I editing events in the mouse brain transcriptome. Most novel sites are located in intronic regions. Unlike previously assumed, we show that both ADAR (ADAR1) and ADARB1 (ADAR2) can edit repeat elements and regular transcripts to the same extent. We find that inhibition of splicing primarily increases editing levels at hundreds of sites, suggesting that reduced splicing efficiency extends the exposure of intronic and exonic sequences to ADAR enzymes. Lack of splicing factors NOVA1 or NOVA2 changes global editing levels, demonstrating that alternative splicing factors can modulate RNA editing. Finally, we show that intron retention rates correlate with editing levels across different brain tissues. We therefore demonstrate that splicing efficiency is a major factor controlling tissue-specific differences in editing levels.
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Affiliation(s)
- Konstantin Licht
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Utkarsh Kapoor
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Fabian Amman
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria.,Institute of Theoretical Biochemistry, University of Vienna, A-1090 Vienna, Austria
| | - Ernesto Picardi
- Department of Biosciences, Biotechnologies, and Biopharmaceutics, University of Bari, I-70126 Bari, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, I-70126 Bari, Italy
| | - David Martin
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Prajakta Bajad
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
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95
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Inosine Pranobex: A Key Player in the Game Against a Wide Range of Viral Infections and Non-Infectious Diseases. Adv Ther 2019; 36:1878-1905. [PMID: 31168764 PMCID: PMC6822865 DOI: 10.1007/s12325-019-00995-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Indexed: 02/03/2023]
Abstract
Inosine pranobex (IP), commonly known as inosine acedoben dimepranol, isoprinosine and methisoprinol, has been proven to positively impact the host’s immune system, by enhancing T-cell lymphocyte proliferation and activity of natural killer cells, increasing levels of pro-inflammatory cytokines, and thereby restoring deficient responses in immunosuppressed patients. At the same time, it has been shown that it can affect viral RNA levels and hence inhibit growth of several viruses. Due to its immunomodulatory and antiviral properties, and its safety profile, it has been widely used since 1971 against viral infections and diseases, among which subacute sclerosis panencephalitis, herpes simplex virus, human papilloma virus, human immunodeficiency virus, influenza and acute respiratory infections, cytomegalovirus and Epstein–Barr virus infections. Following an analysis of almost five decades of scientific literature since its original approval, we here summarize in vivo and in vitro studies manifesting the means in which IP impacts the host’s immune system. We also provide a synopsis of therapeutic trials in the majority of which IP was found to have a beneficial effect. Lastly, positive results from limited studies, suggesting the putative future use of IP in new therapeutic indications are briefly described. In order to support use of IP against viral infections apart from those already approved, and to establish its use in clinical practice, further well-designed and executed trials are warranted. Funding: Ewopharma International.
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