1
|
Lu G, Shivalila C, Monian P, Yu H, Harding I, Briem S, Byrne M, Faraone A, Friend S, Huth O, Iwamoto N, Kawamoto T, Kumarasamy J, Lamattina A, Longo K, McCarthy L, McGlynn A, Molski A, Pan Q, Pu T, Purcell-Estabrook E, Rossi J, Standley S, Thomas C, Walen A, Yang H, Kandasamy P, Vargeese C. Rational design of base, sugar and backbone modifications improves ADAR-mediated RNA editing. Nucleic Acids Res 2024:gkae681. [PMID: 39149897 DOI: 10.1093/nar/gkae681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 07/20/2024] [Accepted: 07/25/2024] [Indexed: 08/17/2024] Open
Abstract
AIMers are short, chemically modified oligonucleotides that induce A-to-I RNA editing through interaction with endogenous adenosine deaminases acting on RNA (ADAR) enzymes. Here, we describe the development of new AIMer designs with base, sugar and backbone modifications that improve RNA editing efficiency over our previous design. AIMers incorporating a novel pattern of backbone and 2' sugar modifications support enhanced editing efficiency across multiple sequences. Further efficiency gains were achieved through incorporation of an N-3-uridine (N3U), in place of cytidine (C), in the 'orphan base' position opposite the edit site. Molecular modeling suggests that N3U might enhance ADAR catalytic activity by stabilizing the AIMer-ADAR interaction and potentially reducing the energy required to flip the target base into the active site. Supporting this hypothesis, AIMers containing N3U consistently enhanced RNA editing over those containing C across multiple target sequences and multiple nearest neighbor sequence combinations. AIMers combining N3U and the novel pattern of 2' sugar chemistry and backbone modifications improved RNA editing both in vitro and in vivo. We provide detailed N3U synthesis methods and, for the first time, explore the impact of N3U and its analogs on ADAR-mediated RNA editing efficiency and targetable sequence space.
Collapse
Affiliation(s)
| | | | | | - Hui Yu
- Wave Life Sciences, Cambridge, MA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Tom Pu
- Wave Life Sciences, Cambridge, MA, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
2
|
Belur NR, Bustos BI, Lubbe SJ, Mazzulli JR. Nuclear aggregates of NONO/SFPQ and A-to-I-edited RNA in Parkinson's disease and dementia with Lewy bodies. Neuron 2024; 112:2558-2580.e13. [PMID: 38761794 PMCID: PMC11309915 DOI: 10.1016/j.neuron.2024.05.003] [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] [Received: 05/27/2023] [Revised: 03/06/2024] [Accepted: 05/01/2024] [Indexed: 05/20/2024]
Abstract
Neurodegenerative diseases are commonly classified as proteinopathies that are defined by the aggregation of a specific protein. Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are classified as synucleinopathies since α-synuclein (α-syn)-containing inclusions histopathologically define these diseases. Unbiased biochemical analysis of PD and DLB patient material unexpectedly revealed novel pathological inclusions in the nucleus comprising adenosine-to-inosine (A-to-I)-edited mRNAs and NONO and SFPQ proteins. These inclusions showed no colocalization with Lewy bodies and accumulated at levels comparable to α-syn. NONO and SFPQ aggregates reduced the expression of the editing inhibitor ADAR3, increasing A-to-I editing mainly within human-specific, Alu-repeat regions of axon, synaptic, and mitochondrial transcripts. Inosine-containing transcripts aberrantly accumulated in the nucleus, bound tighter to recombinant purified SFPQ in vitro, and potentiated SFPQ aggregation in human dopamine neurons, resulting in a self-propagating pathological state. Our data offer new insight into the inclusion composition and pathophysiology of PD and DLB.
Collapse
Affiliation(s)
- Nandkishore R Belur
- The Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Bernabe I Bustos
- The Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Steven J Lubbe
- The Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Simpson Querrey Center for Neurogenetics, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA
| | - Joseph R Mazzulli
- The Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
| |
Collapse
|
3
|
Schneider N, Steinberg R, Ben-David A, Valensi J, David-Kadoch G, Rosenwasser Z, Banin E, Levanon EY, Sharon D, Ben-Aroya S. A pipeline for identifying guide RNA sequences that promote RNA editing of nonsense mutations that cause inherited retinal diseases. MOLECULAR THERAPY. NUCLEIC ACIDS 2024; 35:102130. [PMID: 38375504 PMCID: PMC10875612 DOI: 10.1016/j.omtn.2024.102130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 01/24/2024] [Indexed: 02/21/2024]
Abstract
Adenosine deaminases acting on RNA (ADARs) are endogenous enzymes catalyzing the deamination of adenosines to inosines, which are then read as guanosines during translation. This ability to recode makes ADAR an attractive therapeutic tool to edit genetic mutations and reprogram genetic information at the mRNA level. Using the endogenous ADARs and guiding them to a selected target has promising therapeutic potential. Indeed, different studies have reported several site-directed RNA-editing approaches for making targeted base changes in RNA molecules. The basic strategy has been to use guide RNAs (gRNAs) that hybridize and form a double-stranded RNA (dsRNA) structure with the desired RNA target because of ADAR activity in regions of dsRNA formation. Here we report on a novel pipeline for identifying disease-causing variants as candidates for RNA editing, using a yeast-based screening system to select efficient gRNAs for editing of nonsense mutations, and test them in a human cell line reporter system. We have used this pipeline to modify the sequence of transcripts carrying nonsense mutations that cause inherited retinal diseases in the FAM161A, KIZ, TRPM1, and USH2A genes. Our approach can serve as a basis for gene therapy intervention in knockin mouse models and ultimately in human patients.
Collapse
Affiliation(s)
- Nina Schneider
- Division of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Ricky Steinberg
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 206, Room B-840, Ramat Gan 52900, Israel
| | - Amit Ben-David
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 206, Room B-840, Ramat Gan 52900, Israel
| | - Johanna Valensi
- Division of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Galit David-Kadoch
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 206, Room B-840, Ramat Gan 52900, Israel
| | - Zohar Rosenwasser
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 206, Room B-840, Ramat Gan 52900, Israel
| | - Eyal Banin
- Division of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Erez Y. Levanon
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 206, Room B-840, Ramat Gan 52900, Israel
| | - Dror Sharon
- Division of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Shay Ben-Aroya
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 206, Room B-840, Ramat Gan 52900, Israel
| |
Collapse
|
4
|
Budzko L, Hoffa-Sobiech K, Jackowiak P, Figlerowicz M. Engineered deaminases as a key component of DNA and RNA editing tools. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 34:102062. [PMID: 38028200 PMCID: PMC10661471 DOI: 10.1016/j.omtn.2023.102062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
Over recent years, zinc-dependent deaminases have attracted increasing interest as key components of nucleic acid editing tools that can generate point mutations at specific sites in either DNA or RNA by combining a targeting module (such as a catalytically impaired CRISPR-Cas component) and an effector module (most often a deaminase). Deaminase-based molecular tools are already being utilized in a wide spectrum of therapeutic and research applications; however, their medical and biotechnological potential seems to be much greater. Recent reports indicate that the further development of nucleic acid editing systems depends largely on our ability to engineer the substrate specificity and catalytic activity of the editors themselves. In this review, we summarize the current trends and achievements in deaminase engineering. The presented data indicate that the potential of these enzymes has not yet been fully revealed or understood. Several examples show that even relatively minor changes in the structure of deaminases can give them completely new and unique properties.
Collapse
Affiliation(s)
- Lucyna Budzko
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Karolina Hoffa-Sobiech
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Paulina Jackowiak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Marek Figlerowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| |
Collapse
|
5
|
Jacobsen CS, Salvador P, Yung JF, Kragness S, Mendoza HG, Mandel G, Beal PA. Library Screening Reveals Sequence Motifs That Enable ADAR2 Editing at Recalcitrant Sites. ACS Chem Biol 2023; 18:2188-2199. [PMID: 37040436 PMCID: PMC10581013 DOI: 10.1021/acschembio.3c00107] [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: 04/13/2023]
Abstract
Adenosine deaminases acting on RNA (ADARs) catalyze the hydrolytic deamination of adenosine to inosine in duplex RNA. The inosine product preferentially base pairs with cytidine resulting in an effective A-to-G edit in RNA. ADAR editing can result in a recoding event alongside other alterations to RNA function. A consequence of ADARs' selective activity on duplex RNA is that guide RNAs (gRNAs) can be designed to target an adenosine of interest and promote a desired recoding event. One of ADAR's main limitations is its preference to edit adenosines with specific 5' and 3' nearest neighbor nucleotides (e.g., 5' U, 3' G). Current rational design approaches are well-suited for this ideal sequence context, but limited when applied to difficult-to-edit sites. Here we describe a strategy for the in vitro evaluation of very large libraries of ADAR substrates (En Masse Evaluation of RNA Guides, EMERGe). EMERGe allows for a comprehensive screening of ADAR substrate RNAs that complements current design approaches. We used this approach to identify sequence motifs for gRNAs that enable editing in otherwise difficult-to-edit target sites. A guide RNA bearing one of these sequence motifs enabled the cellular repair of a premature termination codon arising from mutation of the MECP2 gene associated with Rett Syndrome. EMERGe provides an advancement in screening that not only allows for novel gRNA design, but also furthers our understanding of ADARs' specific RNA-protein interactions.
Collapse
Affiliation(s)
- Casey S. Jacobsen
- Department of Chemistry, University of California, Davis, Davis, CA, USA, 95616
| | - Prince Salvador
- Department of Chemistry, University of California, Davis, Davis, CA, USA, 95616
| | - John F. Yung
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA, 97239
| | - Sabrina Kragness
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA, 97239
| | - Herra G. Mendoza
- Department of Chemistry, University of California, Davis, Davis, CA, USA, 95616
| | - Gail Mandel
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA, 97239
| | - Peter A. Beal
- Department of Chemistry, University of California, Davis, Davis, CA, USA, 95616
| |
Collapse
|
6
|
Mendoza HG, Beal PA. Chemical Modifications in RNA: Elucidating the Chemistry of dsRNA-Specific Adenosine Deaminases (ADARs). Acc Chem Res 2023; 56:2489-2499. [PMID: 37665999 PMCID: PMC10826463 DOI: 10.1021/acs.accounts.3c00390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
The term RNA editing refers to any structural change in an RNA molecule (e.g. insertion, deletion, or base modification) that changes its coding properties and is not a result of splicing. An important class of enzymes involved in RNA editing is the ADAR family (adenosine deaminases acting on RNA), which facilitate the deamination of adenosine (A) to inosine (I) in double-stranded RNA (dsRNA). Inosines are decoded as guanosines (G) in most cellular processes; hence, A-to-I editing can be considered an A-to-G substitution. Among the RNA editing enzymes, ADARs are of particular interest because a large portion of RNA editing events are due to A-to-I editing by the two catalytically active human ADARs (ADAR1 and ADAR2). ADARs have diverse roles in RNA processing, gene expression regulation, and innate immunity; and mutations in the ADAR genes and dysregulated ADAR activity have been associated with cancer, autoimmune diseases, and neurological disorders. A-to-I editing is also currently being explored for correcting disease-causing mutations in the RNA, where therapeutic guide oligonucleotides complementary to the target transcript are used to form a dsRNA substrate and site-specifically direct ADAR editing. Knowledge of the mechanism of ADAR-catalyzed reaction and the origin of its substrate selectivity will allow understanding of ADAR’s role in disease biology and expedite the process of developing ADAR-targeted therapeutics. Chemically modified oligonucleotides provide a versatile platform for modulating the activity and interrogating the structure, function, and selectivity of nucleic acid binding or modifying proteins. In this account, we provide an overview of oligonucleotide modifications that have allowed us to gain deeper understanding of ADAR’s molecular mechanisms, which we utilize in the rational design and optimization of ADAR activity modulators. First, we describe the use of the nucleoside analog 8-azanebularine (8-azaN) to generate high-affinity ADAR-RNA complexes for biochemical and biophysical studies with ADARs, with particular emphasis on X-ray crystallography. We then discuss key observations derived from the crystal structures of ADAR bound to 8-azaN-modified RNA duplexes and describe how these findings provided insight into ADAR editing optimization by introducing nucleoside modifications at various positions in synthetic guide strands. We also present the informed design of 8-azaN-modified RNA duplexes that selectively bind and inhibit ADAR1 but not the closely-related ADAR2 enzyme. Finally, we conclude with some open questions on ADAR structure and substrate recognition and share our current endeavors in the development of ADAR guide oligonucleotides and inhibitors.
Collapse
Affiliation(s)
- Herra G. Mendoza
- Department of Chemistry, University of California, Davis, CA 95616 USA
| | - Peter A. Beal
- Department of Chemistry, University of California, Davis, CA 95616 USA
| |
Collapse
|
7
|
Avram-Shperling A, Kopel E, Twersky I, Gabay O, Ben-David A, Karako-Lampert S, Rosenthal JJC, Levanon EY, Eisenberg E, Ben-Aroya S. Identification of exceptionally potent adenosine deaminases RNA editors from high body temperature organisms. PLoS Genet 2023; 19:e1010661. [PMID: 36877730 PMCID: PMC10019624 DOI: 10.1371/journal.pgen.1010661] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 03/16/2023] [Accepted: 02/08/2023] [Indexed: 03/07/2023] Open
Abstract
The most abundant form of RNA editing in metazoa is the deamination of adenosines into inosines (A-to-I), catalyzed by ADAR enzymes. Inosines are read as guanosines by the translation machinery, and thus A-to-I may lead to protein recoding. The ability of ADARs to recode at the mRNA level makes them attractive therapeutic tools. Several approaches for Site-Directed RNA Editing (SDRE) are currently under development. A major challenge in this field is achieving high on-target editing efficiency, and thus it is of much interest to identify highly potent ADARs. To address this, we used the baker yeast Saccharomyces cerevisiae as an editing-naïve system. We exogenously expressed a range of heterologous ADARs and identified the hummingbird and primarily mallard-duck ADARs, which evolved at 40-42°C, as two exceptionally potent editors. ADARs bind to double-stranded RNA structures (dsRNAs), which in turn are temperature sensitive. Our results indicate that species evolved to live with higher core body temperatures have developed ADAR enzymes that target weaker dsRNA structures and would therefore be more effective than other ADARs. Further studies may use this approach to isolate additional ADARs with an editing profile of choice to meet specific requirements, thus broadening the applicability of SDRE.
Collapse
Affiliation(s)
- Adi Avram-Shperling
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
- The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Eli Kopel
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Itamar Twersky
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Orshay Gabay
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Amit Ben-David
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | | | - Joshua J. C. Rosenthal
- The Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
| | - Erez Y. Levanon
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
- The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (EE); (SB-A)
| | - Shay Ben-Aroya
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
- * E-mail: (EE); (SB-A)
| |
Collapse
|
8
|
Han W, Huang W, Wei T, Ye Y, Mao M, Wang Z. Programmable RNA base editing with a single gRNA-free enzyme. Nucleic Acids Res 2022; 50:9580-9595. [PMID: 36029126 PMCID: PMC9458445 DOI: 10.1093/nar/gkac713] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 07/02/2022] [Accepted: 08/09/2022] [Indexed: 12/24/2022] Open
Abstract
Programmable RNA editing enables rewriting gene expression without changing genome sequences. Current tools for specific RNA editing dependent on the assembly of guide RNA into an RNA/protein complex, causing delivery barrier and low editing efficiency. We report a new gRNA-free system, RNA editing with individual RNA-binding enzyme (REWIRE), to perform precise base editing with a single engineered protein. This artificial enzyme contains a human-originated programmable PUF domain to specifically recognize RNAs and different deaminase domains to achieve efficient A-to-I or C-to-U editing, which achieved 60-80% editing rate in human cells, with a few non-specific editing sites in the targeted region and a low level off-target effect globally. The RNA-binding domain in REWIREs was further optimized to improve editing efficiency and minimize off-target effects. We applied the REWIREs to correct disease-associated mutations and achieve both types of base editing in mice. As a single-component system originated from human proteins, REWIRE presents a precise and efficient RNA editing platform with broad applicability.
Collapse
Affiliation(s)
- Wenjian Han
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wendi Huang
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tong Wei
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanwen Ye
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Miaowei Mao
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Zefeng Wang
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| |
Collapse
|
9
|
Han RC, MacLaren RE. RNA gene editing in the eye and beyond: The neglected tool of the gene editing armatorium? INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2022; 372:175-205. [PMID: 36064264 DOI: 10.1016/bs.ircmb.2022.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RNA editing allows correction of pathological point mutations without permanently altering genomic DNA. Theoretically targetable to any RNA type and site, its flexibility and reversibility makes it a potentially powerful gene editing tool. RNA editing offers a host of potential advantages in specific niches when compared to currently available alternative gene manipulation techniques. Unlike DNA editors, which are currently too large to be delivered in vivo using a viral vector, smaller RNA editors fit easily within the capabilities of an adeno-associated virus (AAV). Unlike gene augmentation, which is limited by gene size and viral packaging constraints, RNA editing may correct transcripts too long to fit within a viral vector. In this article we examine the development of RNA editing and discuss potential applications and pitfalls. We argue that, although in its infancy, an RNA editing approach can offer unique advantages for selected retinal diseases.
Collapse
Affiliation(s)
- Ruofan Connie Han
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom; Oxford Eye Hospital, John Radcliffe, Oxford, United Kingdom
| |
Collapse
|
10
|
Doherty EE, Wilcox XE, van Sint Fiet L, Kemmel C, Turunen JJ, Klein B, Tantillo DJ, Fisher AJ, Beal PA. Rational Design of RNA Editing Guide Strands: Cytidine Analogs at the Orphan Position. J Am Chem Soc 2021; 143:6865-6876. [PMID: 33939417 PMCID: PMC8608393 DOI: 10.1021/jacs.0c13319] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adenosine Deaminases Acting on RNA (ADARs) convert adenosine to inosine in double stranded RNA. Human ADARs can be directed to predetermined target sites in the transcriptome by complementary guide strands, allowing for the correction of disease-causing mutations at the RNA level. Here we use structural information available for ADAR2-RNA complexes to guide the design of nucleoside analogs for the position in the guide strand that contacts a conserved glutamic acid residue in ADARs (E488 in human ADAR2), which flips the adenosine into the ADAR active site for deamination. Mutating this residue to glutamine (E488Q) results in higher activity because of the hydrogen bond donating ability of Q488 to N3 of the orphan cytidine on the guide strand. We describe the evaluation of cytidine analogs for this position that stabilize an activated conformation of the enzyme-RNA complex and increase catalytic rate for deamination by the wild-type enzyme. A new crystal structure of ADAR2 bound to duplex RNA bearing a cytidine analog revealed a close contact between E488, stabilized by an additional hydrogen bond and altered charge distribution when compared to cytidine. In human cells and mouse primary liver fibroblasts, this single nucleotide modification increased directed editing yields when compared to an otherwise identical guide oligonucleotide. Our results show that modification of the guide RNA can mimic the effect of hyperactive mutants and advance the approach of recruiting endogenous ADARs for site-directed RNA editing.
Collapse
Affiliation(s)
- Erin E Doherty
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Xander E Wilcox
- Department of Chemistry, University of California, Davis, California 95616, United States
| | | | | | | | - Bart Klein
- ProQR Therapeutics, 2333 CK Leiden, The Netherlands
| | - Dean J Tantillo
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Andrew J Fisher
- Department of Chemistry, University of California, Davis, California 95616, United States
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616, United States
| | - Peter A Beal
- Department of Chemistry, University of California, Davis, California 95616, United States
| |
Collapse
|
11
|
Malik TN, Doherty EE, Gaded VM, Hill TM, Beal PA, Emeson RB. Regulation of RNA editing by intracellular acidification. Nucleic Acids Res 2021; 49:4020-4036. [PMID: 33721028 PMCID: PMC8053123 DOI: 10.1093/nar/gkab157] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/03/2021] [Accepted: 02/25/2021] [Indexed: 12/13/2022] Open
Abstract
The hydrolytic deamination of adenosine-to-inosine (A-to-I) by RNA editing is a widespread post-transcriptional modification catalyzed by the adenosine deaminase acting on RNA (ADAR) family of proteins. ADAR-mediated RNA editing modulates cellular pathways involved in innate immunity, RNA splicing, RNA interference, and protein recoding, and has been investigated as a strategy for therapeutic intervention of genetic disorders. Despite advances in basic and translational research, the mechanisms regulating RNA editing are poorly understood. Though several trans-acting regulators of editing have been shown to modulate ADAR protein expression, previous studies have not identified factors that modulate ADAR catalytic activity. Here, we show that RNA editing increases upon intracellular acidification, and that these effects are predominantly explained by both enhanced ADAR base-flipping and deamination rate at acidic pH. We also show that the extent of RNA editing increases with the reduction in pH associated with conditions of cellular hypoxia.
Collapse
Affiliation(s)
- Turnee N Malik
- Training Program in Neuroscience, Vanderbilt University, Nashville, TN 37232, USA
| | - Erin E Doherty
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Vandana M Gaded
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Theodore M Hill
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Peter A Beal
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Ronald B Emeson
- Training Program in Neuroscience, Vanderbilt University, Nashville, TN 37232, USA.,Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| |
Collapse
|
12
|
Kantor A, McClements ME, Peddle CF, Fry LE, Salman A, Cehajic-Kapetanovic J, Xue K, MacLaren RE. CRISPR genome engineering for retinal diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 182:29-79. [PMID: 34175046 DOI: 10.1016/bs.pmbts.2021.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Novel gene therapy treatments for inherited retinal diseases have been at the forefront of translational medicine over the past couple of decades. Since the discovery of CRISPR mechanisms and their potential application for the treatment of inherited human conditions, it seemed inevitable that advances would soon be made using retinal models of disease. The development of CRISPR technology for gene therapy and its increasing potential to selectively target disease-causing nucleotide changes has been rapid. In this chapter, we discuss the currently available CRISPR toolkit and how it has been and can be applied in the future for the treatment of inherited retinal diseases. These blinding conditions have until now had limited opportunity for successful therapeutic intervention, but the discovery of CRISPR has created new hope of achieving such, as we discuss within this chapter.
Collapse
Affiliation(s)
- Ariel Kantor
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom.
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Caroline F Peddle
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Lewis E Fry
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Ahmed Salman
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Kanmin Xue
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| |
Collapse
|
13
|
Porto EM, Komor AC, Slaymaker IM, Yeo GW. Base editing: advances and therapeutic opportunities. Nat Rev Drug Discov 2020; 19:839-859. [PMID: 33077937 PMCID: PMC7721651 DOI: 10.1038/s41573-020-0084-6] [Citation(s) in RCA: 217] [Impact Index Per Article: 54.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2020] [Indexed: 12/19/2022]
Abstract
Base editing - the introduction of single-nucleotide variants (SNVs) into DNA or RNA in living cells - is one of the most recent advances in the field of genome editing. As around half of known pathogenic genetic variants are due to SNVs, base editing holds great potential for the treatment of numerous genetic diseases, through either temporary RNA or permanent DNA base alterations. Recent advances in the specificity, efficiency, precision and delivery of DNA and RNA base editors are revealing exciting therapeutic opportunities for these technologies. We expect the correction of single point mutations will be a major focus of future precision medicine.
Collapse
Affiliation(s)
- Elizabeth M Porto
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Alexis C Komor
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA.
| | - Ian M Slaymaker
- Synthetic Biology Department, Beam Therapeutics, Cambridge, MA, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA
- Biomedical Sciences and Bioinformatics and Systems Biology Graduate Programs, University of California, San Diego, La Jolla, CA, USA
- Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, USA
| |
Collapse
|
14
|
Wang Y, Chung DH, Monteleone LR, Li J, Chiang Y, Toney MD, Beal PA. RNA binding candidates for human ADAR3 from substrates of a gain of function mutant expressed in neuronal cells. Nucleic Acids Res 2020; 47:10801-10814. [PMID: 31552420 PMCID: PMC6846710 DOI: 10.1093/nar/gkz815] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 08/26/2019] [Accepted: 09/16/2019] [Indexed: 12/18/2022] Open
Abstract
Human ADAR3 is a catalytically inactive member of the Adenosine Deaminase Acting on RNA (ADAR) protein family, whose active members catalyze A-to-I RNA editing in metazoans. Until now, the reasons for the catalytic incapability of ADAR3 has not been defined and its biological function rarely explored. Yet, its exclusive expression in the brain and involvement in learning and memory suggest a central role in the nervous system. Here we describe the engineering of a catalytically active ADAR3 enzyme using a combination of computational design and functional screening. Five mutations (A389V, V485I, E527Q, Q549R and Q733D) engender RNA deaminase in human ADAR3. By way of its catalytic activity, the ADAR3 pentamutant was used to identify potential binding targets for wild type ADAR3 in a human glioblastoma cell line. Novel ADAR3 binding sites discovered in this manner include the 3'-UTRs of the mRNAs encoding early growth response 1 (EGR1) and dual specificity phosphatase 1 (DUSP1); both known to be activity-dependent immediate early genes that respond to stimuli in the brain. Further studies reveal that the wild type ADAR3 protein can regulate transcript levels for DUSP1 and EGR1, suggesting a novel role ADAR3 may play in brain function.
Collapse
Affiliation(s)
- Yuru Wang
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Dong Hee Chung
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Leanna R Monteleone
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Jie Li
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Yao Chiang
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Michael D Toney
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Peter A Beal
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| |
Collapse
|
15
|
Fry LE, Peddle CF, Barnard AR, McClements ME, MacLaren RE. RNA editing as a therapeutic approach for retinal gene therapy requiring long coding sequences. Int J Mol Sci 2020; 21:ijms21030777. [PMID: 31991730 PMCID: PMC7037314 DOI: 10.3390/ijms21030777] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/26/2022] Open
Abstract
RNA editing aims to treat genetic disease through altering gene expression at the transcript level. Pairing site-directed RNA-targeting mechanisms with engineered deaminase enzymes allows for the programmable correction of G>A and T>C mutations in RNA. This offers a promising therapeutic approach for a range of genetic diseases. For inherited retinal degenerations caused by point mutations in large genes not amenable to single-adeno-associated viral (AAV) gene therapy such as USH2A and ABCA4, correcting RNA offers an alternative to gene replacement. Genome editing of RNA rather than DNA may offer an improved safety profile, due to the transient and potentially reversible nature of edits made to RNA. This review considers the current site-directing RNA editing systems, and the potential to translate these to the clinic for the treatment of inherited retinal degeneration.
Collapse
Affiliation(s)
- Lewis E. Fry
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
- Correspondence:
| | - Caroline F. Peddle
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Alun R. Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| |
Collapse
|
16
|
Wang Y, Park S, Beal PA. Selective Recognition of RNA Substrates by ADAR Deaminase Domains. Biochemistry 2018; 57:1640-1651. [PMID: 29457714 DOI: 10.1021/acs.biochem.7b01100] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Adenosine deamination is one of the most prevalent post-transcriptional modifications in mRNA and is catalyzed by ADAR1 and ADAR2 in humans. ADAR1 and ADAR2 have different substrate selectivity, which is believed to mainly originate from the proteins' deaminase domains (hADAR1d and hADAR2d, respectively). RNA-seq of the Saccharomyces cerevisiae transcriptome subjected to ADAR-catalyzed RNA editing identified substrates with common secondary structure features preferentially edited by hADAR1d over hADAR2d. The relatively small size and efficient reaction of one of these substrates suggested it could be useful for further study of the hADAR1d reaction. Indeed, a short hairpin stem from the S. cerevisiae HER1 mRNA was efficiently deaminated by hADAR1d and used to generate an hADAR1d-specific fluorescent reporter of editing activity. Using substrates preferred by either hADAR1d or hADAR2d in vitro, we found that a chimeric protein bearing an RNA-binding loop from hADAR2d grafted onto hADAR1d showed ADAR2-like selectivity. Finally, a high-throughput mutagenesis analysis (Sat-FACS-Seq) of conserved residues in an RNA-binding loop of hADAR1d revealed essential amino acids for function, advancing our understanding of RNA recognition by this domain.
Collapse
Affiliation(s)
- Yuru Wang
- Department of Chemistry , University of California , One Shields Ave , Davis , California 95616 , United States
| | - SeHee Park
- Department of Chemistry , University of California , One Shields Ave , Davis , California 95616 , United States
| | - Peter A Beal
- Department of Chemistry , University of California , One Shields Ave , Davis , California 95616 , United States
| |
Collapse
|
17
|
Xu W, Rahman R, Rosbash M. Mechanistic implications of enhanced editing by a HyperTRIBE RNA-binding protein. RNA (NEW YORK, N.Y.) 2018; 24:173-182. [PMID: 29127211 PMCID: PMC5769745 DOI: 10.1261/rna.064691.117] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 11/10/2017] [Indexed: 05/21/2023]
Abstract
We previously developed TRIBE, a method for the identification of cell-specific RNA-binding protein targets. TRIBE expresses an RBP of interest fused to the catalytic domain (cd) of the RNA-editing enzyme ADAR and performs adenosine-to-inosine editing on RNA targets of the RBP. However, target identification is limited by the low editing efficiency of the ADARcd. Here we describe HyperTRIBE, which carries a previously characterized hyperactive mutation (E488Q) of the ADARcd. HyperTRIBE identifies dramatically more editing sites, many of which are also edited by TRIBE but at a much lower editing frequency. HyperTRIBE therefore more faithfully recapitulates the known binding specificity of its RBP than TRIBE. In addition, separating RNA binding from the enhanced editing activity of the HyperTRIBE ADAR catalytic domain sheds light on the mechanism of ADARcd editing as well as the enhanced activity of the HyperADARcd.
Collapse
Affiliation(s)
- Weijin Xu
- Department of Biology, Howard Hughes Medical Institute and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Reazur Rahman
- Department of Biology, Howard Hughes Medical Institute and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Michael Rosbash
- Department of Biology, Howard Hughes Medical Institute and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02453, USA
| |
Collapse
|
18
|
Cox DBT, Gootenberg JS, Abudayyeh OO, Franklin B, Kellner MJ, Joung J, Zhang F. RNA editing with CRISPR-Cas13. Science 2017; 358:1019-1027. [PMID: 29070703 DOI: 10.1126/science.aaq0180] [Citation(s) in RCA: 1081] [Impact Index Per Article: 154.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 10/16/2017] [Indexed: 12/15/2022]
Abstract
Nucleic acid editing holds promise for treating genetic disease, particularly at the RNA level, where disease-relevant sequences can be rescued to yield functional protein products. Type VI CRISPR-Cas systems contain the programmable single-effector RNA-guided ribonuclease Cas13. We profiled type VI systems in order to engineer a Cas13 ortholog capable of robust knockdown and demonstrated RNA editing by using catalytically inactive Cas13 (dCas13) to direct adenosine-to-inosine deaminase activity by ADAR2 (adenosine deaminase acting on RNA type 2) to transcripts in mammalian cells. This system, referred to as RNA Editing for Programmable A to I Replacement (REPAIR), which has no strict sequence constraints, can be used to edit full-length transcripts containing pathogenic mutations. We further engineered this system to create a high-specificity variant and minimized the system to facilitate viral delivery. REPAIR presents a promising RNA-editing platform with broad applicability for research, therapeutics, and biotechnology.
Collapse
Affiliation(s)
- David B T Cox
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Science, MIT, Cambridge, MA 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA 02139, USA.,Department of Biology, MIT, Cambridge, MA 02139, USA.,Harvard-MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, USA
| | - Jonathan S Gootenberg
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Science, MIT, Cambridge, MA 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA 02139, USA.,Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Omar O Abudayyeh
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Science, MIT, Cambridge, MA 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA 02139, USA.,Harvard-MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, USA
| | - Brian Franklin
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Science, MIT, Cambridge, MA 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA 02139, USA
| | - Max J Kellner
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Science, MIT, Cambridge, MA 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA 02139, USA
| | - Julia Joung
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA.,McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Science, MIT, Cambridge, MA 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA 02139, USA
| | - Feng Zhang
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA. .,McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Science, MIT, Cambridge, MA 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA 02139, USA
| |
Collapse
|
19
|
Zheng Y, Lorenzo C, Beal PA. DNA editing in DNA/RNA hybrids by adenosine deaminases that act on RNA. Nucleic Acids Res 2017; 45:3369-3377. [PMID: 28132026 PMCID: PMC5389660 DOI: 10.1093/nar/gkx050] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 01/25/2017] [Indexed: 01/08/2023] Open
Abstract
Adenosine deaminases that act on RNA (ADARs) carry out adenosine (A) to inosine (I) editing reactions with a known requirement for duplex RNA. Here, we show that ADARs also react with DNA/RNA hybrid duplexes. Hybrid substrates are deaminated efficiently by ADAR deaminase domains at dA-C mismatches and with E to Q mutations in the base flipping loop of the enzyme. For a long, perfectly matched hybrid, deamination is more efficient with full length ADAR2 than its isolated deaminase domain. Guide RNA strands for directed DNA editing by ADAR were used to target six different 2΄-deoxyadenosines in the M13 bacteriophage ssDNA genome. DNA editing efficiencies varied depending on the sequence context of the editing site consistent with known sequence preferences for ADARs. These observations suggest the reaction within DNA/RNA hybrids may be a natural function of human ADARs. In addition, this work sets the stage for development of a new class of genome editing tools based on directed deamination of 2΄-deoxyadenosines in DNA/RNA hybrids.
Collapse
Affiliation(s)
- Yuxuan Zheng
- Department of Chemistry, University of California, Davis, One Shields Ave, Davis, CA 95616, USA
| | - Claire Lorenzo
- Department of Chemistry, University of California, Davis, One Shields Ave, Davis, CA 95616, USA
| | - Peter A Beal
- Department of Chemistry, University of California, Davis, One Shields Ave, Davis, CA 95616, USA
| |
Collapse
|
20
|
Abstract
Inosine is one of the most common modifications found in human RNAs and the Adenosine Deaminases that act on RNA (ADARs) are the main enzymes responsible for its production. ADARs were first discovered in the 1980s and since then our understanding of ADARs has advanced tremendously. For instance, it is now known that defective ADAR function can cause human diseases. Furthermore, recently solved crystal structures of the human ADAR2 deaminase bound to RNA have provided insights regarding the catalytic and substrate recognition mechanisms. In this chapter, we describe the occurrence of inosine in human RNAs and the newest perspective on the ADAR family of enzymes, including their substrate recognition, catalytic mechanism, regulation as well as the consequences of A-to-I editing, and their relation to human diseases.
Collapse
|
21
|
Wang Y, Beal PA. Probing RNA recognition by human ADAR2 using a high-throughput mutagenesis method. Nucleic Acids Res 2016; 44:9872-9880. [PMID: 27614075 PMCID: PMC5175354 DOI: 10.1093/nar/gkw799] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 08/30/2016] [Accepted: 08/31/2016] [Indexed: 01/05/2023] Open
Abstract
Adenosine deamination is one of the most prevalent post-transcriptional modifications in mRNA. In humans, ADAR1 and ADAR2 catalyze this modification and their malfunction correlates with disease. Recently our laboratory reported crystal structures of the human ADAR2 deaminase domain bound to duplex RNA revealing a protein loop that binds the RNA on the 5′ side of the modification site. This 5′ binding loop appears to be one contributor to substrate specificity differences between ADAR family members. In this study, we endeavored to reveal detailed structure–activity relationships in this loop to advance our understanding of RNA recognition by ADAR2. To achieve this goal, we established a high-throughput mutagenesis approach which allows rapid screening of ADAR variants in single yeast cells and provides quantitative evaluation for enzymatic activity. Using this approach, we determined the importance of specific amino acids at 19 different positions in the ADAR2 5′ binding loop and revealed six residues that provide essential structural elements supporting the fold of the loop and key RNA-binding functional groups. This work provided new insight into RNA recognition by ADAR2 and established a new tool for defining structure–function relationships in ADAR reactions.
Collapse
Affiliation(s)
- Yuru Wang
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Peter A Beal
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| |
Collapse
|