1
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Shimo T, Ueda O, Yamamoto S. Design and evaluation of antisense sequence length for modified mouse U7 small nuclear RNA to induce efficient pre-messenger RNA splicing modulation in vitro. PLoS One 2024; 19:e0305012. [PMID: 38980892 PMCID: PMC11232981 DOI: 10.1371/journal.pone.0305012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 05/21/2024] [Indexed: 07/11/2024] Open
Abstract
Pre-messenger RNA (pre-mRNA) splicing modulation is an attractive approach for investigating the mechanisms of genetic disorders caused by mis-splicing. Previous reports have indicated that a modified U7 small nuclear RNA (U7 snRNA) is a prospective tool for modulating splicing both in vitro and in vivo. To date, very few studies have investigated the role of antisense sequence length in modified U7 snRNA. In this study, we designed a series of antisense sequences with various lengths and evaluated their efficiency in inducing splicing modulation. To express modified U7 snRNAs, we constructed a series of plasmid DNA sequences which codes cytomegalovirus (CMV) enhancer, human U1 promoter, and modified mouse U7 snRNAs with antisense sequences of different lengths. We evaluated in vitro splicing modulation efficiency using a luciferase reporter system for simple and precise evaluation as well as reverse transcription-polymerase chain reaction to monitor splicing patterns. Our in vitro assay findings suggest that antisense sequences of modified mouse U7 snRNAs have an optimal length for efficient splicing modulation, which depends on the target exon. In addition, antisense sequences that were either too long or too short decreased splicing modulation efficiency. To confirm reproducibility, we performed an in vitro assay using two target genes, mouse Fas and mouse Dmd. Together, our data suggests that the antisense sequence length should be optimized for modified mouse U7 snRNAs to induce efficient splicing modulation.
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Affiliation(s)
- Takenori Shimo
- Research Division, Chugai Pharmaceutical Co., Ltd., Yokohama, Kanagawa, Japan
| | - Otoya Ueda
- Research Division, Chugai Pharmaceutical Co., Ltd., Yokohama, Kanagawa, Japan
| | - Satoshi Yamamoto
- Research Division, Chugai Pharmaceutical Co., Ltd., Yokohama, Kanagawa, Japan
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2
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Mashima R, Takada S, Miyamoto Y. RNA-Based Therapeutic Technology. Int J Mol Sci 2023; 24:15230. [PMID: 37894911 PMCID: PMC10607345 DOI: 10.3390/ijms242015230] [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: 09/11/2023] [Revised: 10/09/2023] [Accepted: 10/15/2023] [Indexed: 10/29/2023] Open
Abstract
RNA-based therapy has been an expanding area of clinical research since the COVID-19 outbreak. Often, its comparison has been made to DNA-based gene therapy, such as adeno-associated virus- and lentivirus-mediated therapy. These DNA-based therapies show persistent expression, with maximized therapeutic efficacy. However, accumulating data indicate that proper control of gene expression is occasionally required. For example, in cancer immunotherapy, cytokine response syndrome is detrimental for host animals, while excess activation of the immune system induces supraphysiological cytokines. RNA-based therapy seems to be a rather mild therapy, and it has room to fit unmet medical needs, whereas current DNA-based therapy has unclear issues. This review focused on RNA-based therapy for cancer immunotherapy, hematopoietic disorders, and inherited disorders, which have received attention for possible clinical applications.
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Affiliation(s)
- Ryuichi Mashima
- Department of Clinical Laboratory Medicine, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
| | - Shuji Takada
- Department of Systems BioMedicine, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
| | - Yoshitaka Miyamoto
- Department of Maternal-Fetal Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
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3
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Filonova G, Aartsma-Rus A. Next steps for the optimization of exon therapy for Duchenne muscular dystrophy. Expert Opin Biol Ther 2023; 23:133-143. [PMID: 36655939 DOI: 10.1080/14712598.2023.2169070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
INTRODUCTION It is established that the exon-skipping approach can restore dystrophin in Duchenne muscular dystrophy (DMD) patients. However, dystrophin restoration levels are low, and the field is evolving to provide solutions for improved exon skipping. DMD is a neuromuscular disorder associated with chronic muscle tissue loss attributed to the lack of dystrophin, which causes muscle inflammation, fibrosis formation, and impaired regeneration. Currently, four antisense oligonucleotides (AONs) based on phosphorodiamidate morpholino oligomer (PMO) chemistry are approved by US Food and Drug Administration for exon skipping therapy of eligible DMD patients. AREAS COVERED This review describes a preclinical and clinical experience with approved and newly developed AONs for DMD, outlines efforts that have been done to enhance AON efficiency, reviews challenges of clinical trials, and summarizes the current state of the exon skipping approach in the DMD field. EXPERT OPINION The exon skipping approach for DMD is under development, and several chemical modifications with improved properties are under (pre)-clinical investigation. Despite existing advantages of these modifications, their safety and effectiveness have to be examined in clinical trials, which are planned or ongoing. Furthermore, we propose clinical settings using natural history controls to facilitate studying the functional effect of the therapy.
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Affiliation(s)
| | - Annemieke Aartsma-Rus
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
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4
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Wein N, Vetter TA, Vulin A, Simmons TR, Frair EC, Bradley AJ, Gushchina LV, Almeida CF, Huang N, Lesman D, Rajakumar D, Weiss RB, Flanigan KM. Systemic delivery of an AAV9 exon-skipping vector significantly improves or prevents features of Duchenne muscular dystrophy in the Dup2 mouse. Mol Ther Methods Clin Dev 2022; 26:279-293. [PMID: 35949298 PMCID: PMC9356240 DOI: 10.1016/j.omtm.2022.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 07/08/2022] [Indexed: 11/17/2022]
Abstract
Duchenne muscular dystrophy (DMD) is typically caused by mutations that disrupt the DMD reading frame, but nonsense mutations in the 5′ part of the gene induce utilization of an internal ribosomal entry site (IRES) in exon 5, driving expression of a highly functional N-truncated dystrophin. We have developed an AAV9 vector expressing U7 small nuclear RNAs targeting DMD exon 2 and have tested it in a mouse containing a duplication of exon 2, in which skipping of both exon 2 copies induces IRES-driven expression, and skipping of one copy leads to wild-type dystrophin expression. One-time intravascular injection either at postnatal days 0–1 or at 2 months results in efficient exon skipping and dystrophin expression, and significant protection from functional and pathologic deficits. Immunofluorescence quantification showed 33%–53% average dystrophin intensity and 55%–79% average dystrophin-positive fibers in mice treated in adulthood, with partial amelioration of DMD pathology and correction of DMD-associated alterations in gene expression. In mice treated neonatally, dystrophin immunofluorescence reached 49%–85% of normal intensity and 76%–99% dystrophin-positive fibers, with near-complete correction of dystrophic pathology, and these beneficial effects persisted for at least 6 months. Our results demonstrate the robustness, durability, and safety of exon 2 skipping using scAAV9.U7snRNA.ACCA, supporting its clinical use.
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Affiliation(s)
- Nicolas Wein
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, OH, USA
| | - Tatyana A Vetter
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Adeline Vulin
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Tabatha R Simmons
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Emma C Frair
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Adrienne J Bradley
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Liubov V Gushchina
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Camila F Almeida
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Nianyuan Huang
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Daniel Lesman
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Dhanarajan Rajakumar
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Robert B Weiss
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Kevin M Flanigan
- Center for Gene Therapy, The Abigail Wexner Research Institute, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, OH, USA.,Department of Neurology, The Ohio State University, Columbus, OH, USA
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5
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Rovira E, Moreno B, Razquin N, Hjerpe R, Gonzalez-Lopez M, Barrio R, Ruiz de los Mozos I, Ule J, Pastor F, Blazquez L, Fortes P. U1A is a positive regulator of the expression of heterologous and cellular genes involved in cell proliferation and migration. MOLECULAR THERAPY - NUCLEIC ACIDS 2022; 28:831-846. [PMID: 35664701 PMCID: PMC9136276 DOI: 10.1016/j.omtn.2022.05.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 05/07/2022] [Indexed: 11/16/2022]
Abstract
Here, we show that direct recruitment of U1A to target transcripts can increase gene expression. This is a new regulatory role, in addition to previous knowledge showing that U1A decreases the levels of U1A mRNA and other specific targets. In fact, genome-wide, U1A more often increases rather than represses gene expression and many U1A-upregulated transcripts are directly bound by U1A according to individual nucleotide resolution crosslinking and immunoprecipitation (iCLIP) studies. Interestingly, U1A-mediated positive regulation can be transferred to a heterologous system for biotechnological purposes. Finally, U1A-bound genes are enriched for those involved in cell cycle and adhesion. In agreement with this, higher U1A mRNA expression associates with lower disease-free survival and overall survival in many cancer types, and U1A mRNA levels positively correlate with those of some oncogenes involved in cell proliferation. Accordingly, U1A depletion leads to decreased expression of these genes and the migration-related gene CCN2/CTGF, which shows the strongest regulation by U1A. A decrease in U1A causes a strong drop in CCN2 expression and CTGF secretion and defects in the expression of CTGF EMT targets, cell migration, and proliferation. These results support U1A as a putative therapeutic target for cancer treatment. In addition, U1A-binding sequences should be considered in biotechnological applications.
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Affiliation(s)
- Eric Rovira
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), 31008 Pamplona, Spain
| | - Beatriz Moreno
- Department of Molecular Therapy, Aptamer Unit, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), 31008 Pamplona, Spain
| | - Nerea Razquin
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), 31008 Pamplona, Spain
| | - Roland Hjerpe
- Department of Functional Genomics, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Monika Gonzalez-Lopez
- Department of Functional Genomics, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Rosa Barrio
- Department of Functional Genomics, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Igor Ruiz de los Mozos
- Department of Neuromuscular Diseases, Institute of Neurology, UCL, WC1B5EH London, UK
- RNA Networks Lab, The Francis Crick Institute, NW11BF London, UK
| | - Jernej Ule
- Department of Neuromuscular Diseases, Institute of Neurology, UCL, WC1B5EH London, UK
- RNA Networks Lab, The Francis Crick Institute, NW11BF London, UK
| | - Fernando Pastor
- Department of Molecular Therapy, Aptamer Unit, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), 31008 Pamplona, Spain
- Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Spain
| | - Lorea Blazquez
- Department of Neuromuscular Diseases, Institute of Neurology, UCL, WC1B5EH London, UK
- RNA Networks Lab, The Francis Crick Institute, NW11BF London, UK
- Neurosciences Area, Biodonostia Health Research Institute, 20014 San Sebastian, Spain
- Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain
- Corresponding author. Lorea Blazquez, Department of Neuromuscular Diseases, Institute of Neurology, UCL, WC1B5EH London, UK.
| | - Puri Fortes
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), 31008 Pamplona, Spain
- Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Spain
- Liver and Digestive Diseases Networking Biomedical Research Centre (CIBERehd), Spain
- Spanish Network for Advanced Therapies (TERAV ISCIII), Spain
- Corresponding author. Puri Fortes, Neurosciences Area, Biodonostia Health Research Institute, 20014 San Sebastian, Spain.
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6
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Lesman D, Rodriguez Y, Rajakumar D, Wein N. U7 snRNA, a Small RNA with a Big Impact in Gene Therapy. Hum Gene Ther 2021; 32:1317-1329. [PMID: 34139889 DOI: 10.1089/hum.2021.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The uridine-rich 7 (U7) small nuclear RNA (snRNA) is a component of a small nuclear ribonucleoprotein (snRNP) complex. U7 snRNA naturally contains an antisense sequence that identifies histone premessenger RNAs (pre-mRNAs) and is involved in their 3' end processing. By altering this antisense sequence, researchers have turned U7 snRNA into a versatile tool for targeting pre-mRNAs and modifying splicing. Encapsulating a modified U7 snRNA into a viral vector such as adeno-associated virus (also referred as vectorized exon skipping/inclusion, or VES/VEI) enables the delivery of this highly efficacious splicing modulator into a range of cell lines, primary cells, and tissues. In addition, and in contrast to antisense oligonucleotides, viral delivery of U7 snRNA enables long-term expression of antisense sequences in the nucleus as part of a stable snRNP complex. As a result, VES/VEI has emerged as a promising therapeutic platform for treating a large variety of human diseases caused by errors in pre-mRNA splicing or its regulation. Here we provide an overview of U7 snRNA's natural function and its applications in gene therapy.
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Affiliation(s)
- Daniel Lesman
- Center for Gene Therapy, The Research Institute, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Yacidzohara Rodriguez
- Center for Gene Therapy, The Research Institute, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Dhanarajan Rajakumar
- Center for Gene Therapy, The Research Institute, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Nicolas Wein
- Center for Gene Therapy, The Research Institute, Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pediatric, The Ohio State University, Columbus, Ohio, USA
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7
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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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8
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Gushchina LV, Frair EC, Rohan N, Bradley AJ, Simmons TR, Chavan HD, Chou HJ, Eggers M, Waldrop MA, Wein N, Flanigan KM. Lack of Toxicity in Nonhuman Primates Receiving Clinically Relevant Doses of an AAV9.U7snRNA Vector Designed to Induce DMD Exon 2 Skipping. Hum Gene Ther 2021; 32:882-894. [PMID: 33406986 PMCID: PMC10112461 DOI: 10.1089/hum.2020.286] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Therapeutic exon skipping as a treatment for Duchenne muscular dystrophy (DMD) has largely concentrated on the delivery of antisense oligomers to treat out-of-frame exon deletions. Here we report on the preclinical development of an adeno-associated virus (AAV)-encapsidated viral vector containing four copies of the noncoding U7 small nuclear RNA (U7snRNA), each targeted to either the splice donor or the splice acceptor sites of DMD exon 2. We have previously shown that delivery of this vector (scAAV9.U7.ACCA) to the Dup2 mouse model results in expression of full-length dystrophin from wild-type DMD mRNA, as well as an internal ribosome entry site (IRES)-driven isoform translated only in the absence of exon 2 (deletion exon 2 [Del2] mRNA). Here we present the data from a rigorous dose escalation toxicity study in nonhuman primates, encompassing two doses (3 × 1013 and 8 × 1013 vg/kg) and two time points (3 and 6 months postinjection). No evidence for significant toxicity was seen by biochemical, histopathologic, or clinical measures, providing evidence for safety that led to initiation of a first-in-human clinical trial.
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Affiliation(s)
- Liubov V Gushchina
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA
| | - Emma C Frair
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA
| | - Natalie Rohan
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA
| | - Adrienne J Bradley
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA
| | - Tabatha R Simmons
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA
| | | | | | | | - Megan A Waldrop
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Nicolas Wein
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Kevin M Flanigan
- The Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA.,Department of Neurology, The Ohio State University, Columbus, Ohio, USA
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9
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Gadgil A, Raczyńska KD. U7 snRNA: A tool for gene therapy. J Gene Med 2021; 23:e3321. [PMID: 33590603 PMCID: PMC8243935 DOI: 10.1002/jgm.3321] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 01/22/2021] [Accepted: 02/09/2021] [Indexed: 12/25/2022] Open
Abstract
Most U-rich small nuclear ribonucleoproteins (snRNPs) are complexes that mediate the splicing of pre-mRNAs. U7 snRNP is an exception in that it is not involved in splicing but is a key factor in the unique 3' end processing of replication-dependent histone mRNAs. However, by introducing controlled changes in the U7 snRNA histone binding sequence and in the Sm motif, it can be used as an effective tool for gene therapy. The modified U7 snRNP (U7 Sm OPT) is thus not involved in the processing of replication-dependent histone pre-mRNA but targets splicing by inducing efficient skipping or inclusion of selected exons. U7 Sm OPT is of therapeutic importance in diseases that are an outcome of splicing defects, such as myotonic dystrophy, Duchenne muscular dystrophy, amyotrophic lateral sclerosis, β-thalassemia, HIV-1 infection and spinal muscular atrophy. The benefits of using U7 Sm OPT for gene therapy are its compact size, ability to accumulate in the nucleus without causing any toxic effects in the cells, and no immunoreactivity. The risk of transgene misregulation by using U7 Sm OPT is also low because it is involved in correcting the expression of an endogenous gene controlled by its own regulatory elements. Altogether, using U7 Sm OPT as a tool in gene therapy can ensure lifelong treatment, whereas an oligonucleotide or other drug/compound would require repeated administration. It would thus be strategic to harness these unique properties of U7 snRNP and deploy it as a tool in gene therapy.
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Affiliation(s)
- Ankur Gadgil
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of BiologyAdam Mickiewicz UniversityPoznanPoland
- Center for Advanced TechnologyAdam Mickiewicz UniversityPoznanPoland
| | - Katarzyna Dorota Raczyńska
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of BiologyAdam Mickiewicz UniversityPoznanPoland
- Center for Advanced TechnologyAdam Mickiewicz UniversityPoznanPoland
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10
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Stephenson AA, Flanigan KM. Gene editing and modulation for Duchenne muscular dystrophy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 182:225-255. [PMID: 34175043 DOI: 10.1016/bs.pmbts.2021.01.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Duchenne muscular dystrophy (DMD) is a progressive muscle disease caused by loss of dystrophin protein, encoded by the DMD gene. DMD manifests early in childhood as difficulty walking, progresses to loss of ambulation by the teens, and leads to death in early adulthood. Adeno-associated virus-vectorized gene therapies to restore dystrophin protein expression using gene replacement or antisense oligonucleotide-mediated pre-mRNA splicing modulation have emerged, making great strides in uncovering barriers to gene therapies for DMD and other genetic diseases. While this first-generation of DMD therapies are being evaluated in ongoing clinical trials, uncertainties regarding durability and therapeutic efficacy prompted the development of new experimental therapies for DMD that take advantage of somatic cell gene editing. These experimental therapies continue to advance toward clinic trials, but questions remain unanswered regarding safety and translatable efficacy. Here we review the advancements toward treatment of DMD using gene editing and modulation therapies, with an emphasis on those nearest to clinical applications.
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Affiliation(s)
- Anthony A Stephenson
- Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, United States
| | - Kevin M Flanigan
- Center for Gene Therapy, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, United States; Department of Pediatrics, College of Medicine, The Ohio State University, Columbus, OH, United States; Department of Neurology, College of Medicine, The Ohio State University, Columbus, OH, United States.
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11
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Abstract
β-thalassemia is caused by mutations in the β-globin gene which diminishes or abolishes β-globin chain production. This reduction causes an imbalance of the α/β-globin chain ratio and contributes to the pathogenesis of the disease. Several approaches to reduce the imbalance of the α/β ratio using several nucleic acid-based technologies such as RNAi, lentiviral mediated gene therapy, splice switching oligonucleotides (SSOs) and gene editing technology have been investigated extensively. These approaches aim to reduce excess free α-globin, either by reducing the α-globin chain, restoring β-globin expression and reactivating γ-globin expression, leading a reduced disease severity, treatment necessity, treatment interval, and disease complications, thus, increasing the life quality of the patients and alleviating economic burden. Therefore, nucleic acid-based therapy might become a potential targeted therapy for β-thalassemia.
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Affiliation(s)
- Annette d'Arqom
- Graduate Program in Molecular Medicine, Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Pharmacology and Therapy, Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia
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12
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Ferraresi P, Balestra D, Guittard C, Buthiau D, Pan-Petesh B, Maestri I, Farah R, Pinotti M, Giansily-Blaizot M. Next-generation sequencing and recombinant expression characterized aberrant splicing mechanisms and provided correction strategies in factor VII deficiency. Haematologica 2019; 105:829-837. [PMID: 31273093 PMCID: PMC7049351 DOI: 10.3324/haematol.2019.217539] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 07/02/2019] [Indexed: 01/22/2023] Open
Abstract
Despite the exhaustive screening of F7 gene exons and exon-intron boundaries and promoter region, a significant proportion of mutated alleles remains unidentified in patients with coagulation factor VII deficiency. Here, we applied next-generation sequencing to 13 FVII-deficient patients displaying genotype-phenotype discrepancies upon conventional sequencing, and identified six rare intronic variants. Computational analysis predicted splicing effects for three of them, which would strengthen (c.571+78G>A; c.806-329G>A) or create (c.572-392C>G) intronic 5′ splice sites (5′ss). In F7 minigene assays, the c.806-329G>A was ineffective while the c.571+78G>A change led to usage of the +79 cryptic 5′ss with only trace levels of correct transcripts (3% of wild-type), in accordance with factor VII activity levels in homozygotes (1-3% of normal). The c.572-392C>G change led to pseudo-exonization and frame-shift, but also substantial levels of correct transcripts (approx. 70%). However, this variant was associated with the common F7 polymorphic haplotype, predicted to further decrease factor VII levels; this provided some kind of explanation for the 10% factor VII levels in the homozygous patient. Intriguingly, the effect of the c.571+78G>A and c.572-392C>G changes, and particularly of the former (the most severe and well-represented in our cohort), was counteracted by antisense U7snRNA variants targeting the intronic 5′ss, thus demonstrating their pathogenic role. In conclusion, the combination of next-generation sequencing of the entire F7 gene with the minigene expression studies elucidated the molecular bases of factor VII deficiency in 10 of 13 patients, thus improving diagnosis and genetic counseling. It also provided a potential therapeutic approach based on antisense molecules that has been successfully exploited in other disorders.
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Affiliation(s)
- Paolo Ferraresi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Caroline Guittard
- Department of Biological Haematology, CHU Montpellier, Université Montpellier, Montpellier, France
| | - Delphine Buthiau
- Department of Biological Haematology, CHU Montpellier, Université Montpellier, Montpellier, France
| | | | - Iva Maestri
- Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Roula Farah
- Department of Pediatrics, Saint George Hospital University Medical Center, Beirut, Lebanon
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Muriel Giansily-Blaizot
- Department of Biological Haematology, CHU Montpellier, Université Montpellier, Montpellier, France
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13
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Nualkaew T, Jearawiriyapaisarn N, Hongeng S, Fucharoen S, Kole R, Svasti S. Restoration of correct β IVS2-654-globin mRNA splicing and HbA production by engineered U7 snRNA in β-thalassaemia/HbE erythroid cells. Sci Rep 2019; 9:7672. [PMID: 31113996 PMCID: PMC6529457 DOI: 10.1038/s41598-019-43964-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 05/02/2019] [Indexed: 01/03/2023] Open
Abstract
A cytosine to thymine mutation at nucleotide 654 of human β-globin intron 2 (βIVS2-654) is one of the most common mutations causing β-thalassaemia in Chinese and Southeast Asians. This mutation results in aberrant β-globin pre-mRNA splicing and prevents synthesis of β-globin protein. Splicing correction using synthetic splice-switching oligonucleotides (SSOs) has been shown to restore expression of the β-globin protein, but to maintain therapeutically relevant levels of β-globin it would require lifelong administration. Here, we demonstrate long-term splicing correction using U7 snRNA lentiviral vectors engineered to target several pre-mRNA splicing elements on the βIVS2-654-globin pre-mRNA such as cryptic 3' splice site, aberrant 5' splice site, cryptic branch point and an exonic splicing enhancer. A double-target engineered U7 snRNAs targeted to the cryptic branch point and an exonic splicing enhancer, U7.BP + 623, was the most effective in a model cell line, HeLa IVS2-654. Moreover, the therapeutic potential of the vector was demonstrated in erythroid progenitor cells derived from βIVS2-654-thalassaemia/HbE patients, which showed restoration of correctly spliced β-globin mRNA and led to haemoglobin A synthesis, and consequently improved thalassaemic erythroid cell pathology. These results demonstrate proof of concept of using the engineered U7 snRNA lentiviral vector for treatment of β-thalassaemia.
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Affiliation(s)
- Tiwaporn Nualkaew
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Natee Jearawiriyapaisarn
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Suradej Hongeng
- Departments of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Suthat Fucharoen
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | | | - Saovaros Svasti
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand. .,Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand.
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14
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Exon Skipping in a Dysf-Missense Mutant Mouse Model. MOLECULAR THERAPY. NUCLEIC ACIDS 2018; 13:198-207. [PMID: 30292141 PMCID: PMC6172476 DOI: 10.1016/j.omtn.2018.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/16/2018] [Accepted: 08/16/2018] [Indexed: 01/14/2023]
Abstract
Limb girdle muscular dystrophy 2B (LGMD2B) is without treatment and caused by mutations in the dysferlin gene (DYSF). One-third is missense mutations leading to dysferlin aggregation and amyloid formation, in addition to defects in sarcolemmal repair and progressive muscle wasting. Dysferlin-null mouse models do not allow study of the consequences of missense mutations. We generated a new mouse model (MMex38) carrying a missense mutation in exon 38 in analogy to a clinically relevant human DYSF variant (DYSF p.Leu1341Pro). The targeted mutation induces all characteristics of missense mutant dysferlinopathy, including a progressive dystrophic pattern, amyloid formation, and defects in membrane repair. We chose U7 small nuclear RNA (snRNA)-based splice switching to demonstrate a possible exon-skipping strategy in this new animal model. We show that Dysf exons 37 and 38 can successfully be skipped in vivo. Overall, the MMex38 mouse model provides an ideal tool for preclinical development of treatment strategies for dysferlinopathy.
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15
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Yanaizu M, Sakai K, Tosaki Y, Kino Y, Satoh JI. Small nuclear RNA-mediated modulation of splicing reveals a therapeutic strategy for a TREM2 mutation and its post-transcriptional regulation. Sci Rep 2018; 8:6937. [PMID: 29720600 PMCID: PMC5931963 DOI: 10.1038/s41598-018-25204-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/17/2018] [Indexed: 12/30/2022] Open
Abstract
Loss-of-function mutations in TREM2 cause Nasu-Hakola disease (NHD), a rare genetic disease characterized by early-onset dementia with leukoencephalopathy and bone cysts. An NHD-associated mutation, c.482 + 2 T > C, disrupts the splice donor site of intron 3 and causes aberrant skipping of exon 3, resulting in the loss of full-length TREM2 protein. Here, we examined the efficacy of artificial U1 and U7 small nuclear RNAs (snRNAs) designed to enhance exon 3 inclusion. Using mutant TREM2 minigenes, we found that some modified U1, but not U7, snRNAs enhanced exon 3 inclusion and restored TREM2 protein expression. Unexpectedly, we found that exon 3 of wild-type TREM2 is an alternative exon, whose skipping leads to reduced expression of the full-length protein. Indeed, TREM2 protein levels were modulated by modified snRNAs that either promoted or repressed exon 3 inclusion. The splice donor site flanking exon 3 was predicted to be weak, which may explain both the alternative splicing of exon 3 under normal conditions and complete exon skipping when the c.482 + 2 T > C mutation was present. Collectively, our snRNA-based approaches provide a potential therapeutic strategy for NHD-associated mis-splicing and novel insights into the post-transcriptional regulation of TREM2.
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Affiliation(s)
- Motoaki Yanaizu
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
| | - Kenji Sakai
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
| | - Youhei Tosaki
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
| | - Yoshihiro Kino
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan.
| | - Jun-Ichi Satoh
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
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16
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Preedagasamzin S, Nualkaew T, Pongrujikorn T, Jinawath N, Kole R, Fucharoen S, Jearawiriyapaisarn N, Svasti S. Engineered U7 snRNA mediates sustained splicing correction in erythroid cells from β-thalassemia/HbE patients. Biochem Biophys Res Commun 2018; 499:86-92. [DOI: 10.1016/j.bbrc.2018.03.102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 03/13/2018] [Indexed: 11/30/2022]
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17
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Domenger C, Allais M, François V, Léger A, Lecomte E, Montus M, Servais L, Voit T, Moullier P, Audic Y, Le Guiner C. RNA-Seq Analysis of an Antisense Sequence Optimized for Exon Skipping in Duchenne Patients Reveals No Off-Target Effect. MOLECULAR THERAPY-NUCLEIC ACIDS 2017; 10:277-291. [PMID: 29499940 PMCID: PMC5785776 DOI: 10.1016/j.omtn.2017.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 12/16/2017] [Accepted: 12/16/2017] [Indexed: 01/16/2023]
Abstract
Non-coding uridine-rich small nuclear RNAs (UsnRNAs) have emerged in recent years as effective tools for exon skipping for the treatment of Duchenne muscular dystrophy (DMD), a degenerative muscular genetic disorder. We recently showed the high capacity of a recombinant adeno-associated virus (rAAV)-U7snRNA vector to restore the reading frame of the DMD mRNA in the muscles of DMD dogs. We are now moving toward a phase I/II clinical trial with an rAAV-U7snRNA-E53, carrying an antisense sequence designed to hybridize exon 53 of the human DMD messenger. As observed for genome-editing tools, antisense sequences present a risk of off-target effects, reflecting partial hybridization onto unintended transcripts. To characterize the clinical antisense sequence, we studied its expression and explored the occurrence of its off-target effects in human in vitro models of skeletal muscle and liver. We presented a comprehensive methodology combining RNA sequencing and in silico filtering to analyze off-targets. We showed that U7snRNA-E53 induced the effective exon skipping of the DMD transcript without inducing the notable deregulation of transcripts in human cells, neither at gene expression nor at the mRNA splicing level. Altogether, these results suggest that the use of the rAAV-U7snRNA-E53 vector for exon skipping could be safe in eligible DMD patients.
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Affiliation(s)
- Claire Domenger
- INSERM UMR 1089, Université de Nantes, CHU de Nantes, 44200 Nantes, France.
| | - Marine Allais
- INSERM UMR 1089, Université de Nantes, CHU de Nantes, 44200 Nantes, France
| | - Virginie François
- INSERM UMR 1089, Université de Nantes, CHU de Nantes, 44200 Nantes, France
| | - Adrien Léger
- INSERM UMR 1089, Université de Nantes, CHU de Nantes, 44200 Nantes, France
| | - Emilie Lecomte
- INSERM UMR 1089, Université de Nantes, CHU de Nantes, 44200 Nantes, France
| | | | - Laurent Servais
- Institute I-Motion, Hôpital Armand Trousseau, 75012 Paris, France
| | - Thomas Voit
- NIHR Biomedical Research Centre, UCL Institute of Child Health/Great Ormond Street Hospital NHS Trust, WC1N 1EH London, UK
| | - Philippe Moullier
- INSERM UMR 1089, Université de Nantes, CHU de Nantes, 44200 Nantes, France
| | - Yann Audic
- CNRS, UMR 6290 Institut Génétique et Développement de Rennes, Université de Rennes 1, 35000 Rennes, France
| | - Caroline Le Guiner
- INSERM UMR 1089, Université de Nantes, CHU de Nantes, 44200 Nantes, France.
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Alternative Splicing in Genetic Diseases: Improved Diagnosis and Novel Treatment Options. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2017; 335:85-141. [PMID: 29305015 DOI: 10.1016/bs.ircmb.2017.07.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Alternative splicing is an important mechanism to regulate gene expression and to expand the repertoire of gene products in order to accommodate an increase in complexity of multicellular organisms. It needs to be precisely regulated, which is achieved via RNA structure, splicing factors, transcriptional regulation, and chromatin. Changes in any of these factors can lead to disease. These may include the core spliceosome, splicing enhancer/repressor sequences and their interacting proteins, the speed of transcription by RNA polymerase II, and histone modifications. While the basic principle of splicing is well understood, it is still very difficult to predict splicing outcome, due to the multiple levels of regulation. Current molecular diagnostics mainly uses Sanger sequencing of exons, or next-generation sequencing of gene panels or the whole exome. Functional analysis of potential splicing variants is scarce, and intronic variants are often not considered. This likely results in underestimation of the percentage of splicing variants. Understanding how sequence variants may affect splicing is not only crucial for confirmation of diagnosis and for genetic counseling, but also for the development of novel treatment options. These include small molecules, transsplicing, antisense oligonucleotides, and gene therapy. Here we review the current state of molecular mechanisms of splicing regulation and how deregulation can lead to human disease, diagnostics to detect splicing variants, and novel treatment options based on splicing correction.
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19
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Antisense Oligonucleotides Promote Exon Inclusion and Correct the Common c.-32-13T>G GAA Splicing Variant in Pompe Disease. MOLECULAR THERAPY. NUCLEIC ACIDS 2017. [PMID: 28624228 PMCID: PMC5415969 DOI: 10.1016/j.omtn.2017.03.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The most common variant causing Pompe disease is c.-32-13T>G (IVS1) in the acid α-glucosidase (GAA) gene, which weakens the splice acceptor of GAA exon 2 and induces partial and complete exon 2 skipping. It also allows a low level of leaky wild-type splicing, leading to a childhood/adult phenotype. We hypothesized that cis-acting splicing motifs may exist that could be blocked using antisense oligonucleotides (AONs) to promote exon inclusion. To test this, a screen was performed in patient-derived primary fibroblasts using a tiling array of U7 small nuclear RNA (snRNA)-based AONs. This resulted in the identification of a splicing regulatory element in GAA intron 1. We designed phosphorodiamidate morpholino oligomer-based AONs to this element, and these promoted exon 2 inclusion and enhanced GAA enzyme activity to levels above the disease threshold. These results indicate that the common IVS1 GAA splicing variant in Pompe disease is subject to negative regulation, and inhibition of a splicing regulatory element using AONs is able to restore canonical GAA splicing and endogenous GAA enzyme activity.
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20
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Phanthong P, Borwornpinyo S, Kitiyanant N, Jearawiriyapaisarn N, Nuntakarn L, Saetan J, Nualkaew T, Sa-Ngiamsuntorn K, Anurathapan U, Dinnyes A, Kitiyanant Y, Hongeng S. Enhancement of β-Globin Gene Expression in Thalassemic IVS2-654 Induced Pluripotent Stem Cell-Derived Erythroid Cells by Modified U7 snRNA. Stem Cells Transl Med 2017; 6:1059-1069. [PMID: 28213976 PMCID: PMC5442829 DOI: 10.1002/sctm.16-0121] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 11/27/2016] [Accepted: 12/21/2016] [Indexed: 12/30/2022] Open
Abstract
The therapeutic use of patient‐specific induced pluripotent stem cells (iPSCs) is emerging as a potential treatment of β‐thalassemia. Ideally, patient‐specific iPSCs would be genetically corrected by various approaches to treat β‐thalassemia including lentiviral gene transfer, lentivirus‐delivered shRNA, and gene editing. These corrected iPSCs would be subsequently differentiated into hematopoietic stem cells and transplanted back into the same patient. In this article, we present a proof of principle study for disease modeling and screening using iPSCs to test the potential use of the modified U7 small nuclear (sn) RNA to correct a splice defect in IVS2‐654 β‐thalassemia. In this case, the aberration results from a mutation in the human β‐globin intron 2 causing an aberrant splicing of β‐globin pre‐mRNA and preventing synthesis of functional β‐globin protein. The iPSCs (derived from mesenchymal stromal cells from a patient with IVS2‐654 β‐thalassemia/hemoglobin (Hb) E) were transduced with a lentivirus carrying a modified U7 snRNA targeting an IVS2‐654 β‐globin pre‐mRNA in order to restore the correct splicing. Erythroblasts differentiated from the transduced iPSCs expressed high level of correctly spliced β‐globin mRNA suggesting that the modified U7 snRNA was expressed and mediated splicing correction of IVS2‐654 β‐globin pre‐mRNA in these cells. Moreover, a less active apoptosis cascade process was observed in the corrected cells at transcription level. This study demonstrated the potential use of a genetically modified U7 snRNA with patient‐specific iPSCs for the partial restoration of the aberrant splicing process of β‐thalassemia. Stem Cells Translational Medicine2017;6:1059–1069
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Affiliation(s)
| | - Suparerk Borwornpinyo
- Biotechnology.,Excellent Center for Drug Discovery, Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | | | | | - Jirawat Saetan
- Anatomy Department, Faculty of Science, Prince of Songkla University, Songkhla, Thailand
| | | | | | - Usanarat Anurathapan
- Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Andras Dinnyes
- Biotalentum Ltd, Godollo, Hungary.,Molecular Animal Biotechnology Laboratory, Szent Istvan University, Godollo, Hungary
| | - Yindee Kitiyanant
- Departments of Anatomy.,Stem Cell Research Group.,Reproductive Biology Research Group, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Suradej Hongeng
- Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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21
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Viral Vector-Mediated Antisense Therapy for Genetic Diseases. Genes (Basel) 2017; 8:genes8020051. [PMID: 28134780 PMCID: PMC5333040 DOI: 10.3390/genes8020051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/04/2017] [Accepted: 01/17/2017] [Indexed: 01/16/2023] Open
Abstract
RNA plays complex roles in normal health and disease and is becoming an important target for therapeutic intervention; accordingly, therapeutic strategies that modulate RNA function have gained great interest over the past decade. Antisense oligonucleotides (AOs) are perhaps the most promising strategy to modulate RNA expression through a variety of post binding events such as gene silencing through degradative or non-degradative mechanisms, or splicing modulation which has recently demonstrated promising results. However, AO technology still faces issues like poor cellular-uptake, low efficacy in target tissues and relatively rapid clearance from the circulation which means repeated injections are essential to complete therapeutic efficacy. To overcome these limitations, viral vectors encoding small nuclear RNAs have been engineered to shuttle antisense sequences into cells, allowing appropriate subcellular localization with pre-mRNAs and permanent correction. In this review, we outline the different strategies for antisense therapy mediated by viral vectors and provide examples of each approach. We also address the advantages and limitations of viral vector use, with an emphasis on their clinical application.
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22
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Double-target Antisense U1snRNAs Correct Mis-splicing Due to c.639+861C>T and c.639+919G>A GLA Deep Intronic Mutations. MOLECULAR THERAPY-NUCLEIC ACIDS 2016; 5:e380. [PMID: 27779620 PMCID: PMC5095687 DOI: 10.1038/mtna.2016.88] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 08/22/2016] [Indexed: 12/26/2022]
Abstract
Fabry disease is a rare X-linked lysosomal storage disorder caused by deficiency of the α-galactosidase A (α-Gal A) enzyme, which is encoded by the GLA gene. GLA transcription in humans produces a major mRNA encoding α-Gal A and a minor mRNA of unknown function, which retains a 57-nucleotide-long cryptic exon between exons 4 and 5, bearing a premature termination codon. NM_000169.2:c.639+861C>T and NM_000169.2:c.639+919G>A GLA deep intronic mutations have been described to cause Fabry disease by inducing overexpression of the alternatively spliced mRNA, along with a dramatic decrease in the major one. Here, we built a wild-type GLA minigene and two minigenes that carry mutations c.639+861C>T and c.639+919G>A. Once transfected into cells, the minigenes recapitulate the molecular patterns observed in patients, at the mRNA, protein, and enzymatic level. We constructed a set of specific double-target U1asRNAs to correct c.639+861C>T and c.639+919G>A GLA mutations. Efficacy of U1asRNAs in inducing the skipping of the cryptic exon was evaluated upon their transient co-transfection with the minigenes in COS-1 cells, by real-time polymerase chain reaction (PCR), western blot analysis, and α-Gal A enzyme assay. We identified a set of U1asRNAs that efficiently restored α-Gal A enzyme activity and the correct splicing pathways in reporter minigenes. We also identified a unique U1asRNA correcting both mutations as efficently as the mutation-specific U1asRNAs. Our study proves that an exon skipping-based approach recovering α-Gal A activity in the c.639+861C>T and c.639+919G>A GLA mutations is active.
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Abstract
Recent improvements in experimental and computational techniques that are used to study the transcriptome have enabled an unprecedented view of RNA processing, revealing many previously unknown non-canonical splicing events. This includes cryptic events located far from the currently annotated exons and unconventional splicing mechanisms that have important roles in regulating gene expression. These non-canonical splicing events are a major source of newly emerging transcripts during evolution, especially when they involve sequences derived from transposable elements. They are therefore under precise regulation and quality control, which minimizes their potential to disrupt gene expression. We explain how non-canonical splicing can lead to aberrant transcripts that cause many diseases, and also how it can be exploited for new therapeutic strategies.
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24
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Bornert O, Kühl T, Bremer J, van den Akker PC, Pasmooij AM, Nyström A. Analysis of the functional consequences of targeted exon deletion in COL7A1 reveals prospects for dystrophic epidermolysis bullosa therapy. Mol Ther 2016; 24:1302-11. [PMID: 27157667 DOI: 10.1038/mt.2016.92] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/03/2016] [Indexed: 12/18/2022] Open
Abstract
Genetically evoked deficiency of collagen VII causes dystrophic epidermolysis bullosa (DEB)-a debilitating disease characterized by chronic skin fragility and progressive fibrosis. Removal of exons carrying frame-disrupting mutations can reinstate protein expression in genetic diseases. The therapeutic potential of this approach is critically dependent on gene, protein, and disease intrinsic factors. Naturally occurring exon skipping in COL7A1, translating collagen VII, suggests that skipping of exons containing disease-causing mutations may be feasible for the treatment of DEB. However, despite a primarily in-frame arrangement of exons in the COL7A1 gene, no general conclusion of the aptitude of exon skipping for DEB can be drawn, since regulation of collagen VII functionality is complex involving folding, intra- and intermolecular interactions. To directly address this, we deleted two conceptually important exons located at both ends of COL7A1, exon 13, containing recurrent mutations, and exon 105, predicted to impact folding. The resulting recombinantly expressed proteins showed conserved functionality in biochemical and in vitro assays. Injected into DEB mice, the proteins promoted skin stability. By demonstrating functionality of internally deleted collagen VII variants, our study provides support of targeted exon deletion or skipping as a potential therapy to treat a large number of individuals with DEB.
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Affiliation(s)
- Olivier Bornert
- Department of Dermatology, Medical Center - University of Freiburg, Freiburg, Germany
| | - Tobias Kühl
- Department of Dermatology, Medical Center - University of Freiburg, Freiburg, Germany
| | - Jeroen Bremer
- Department of Dermatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Peter C van den Akker
- Department of Dermatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.,Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Anna Mg Pasmooij
- Department of Dermatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Alexander Nyström
- Department of Dermatology, Medical Center - University of Freiburg, Freiburg, Germany
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25
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Lipid-based Transfection Reagents Exhibit Cryo-induced Increase in Transfection Efficiency. MOLECULAR THERAPY. NUCLEIC ACIDS 2016; 5:e290. [PMID: 27111416 PMCID: PMC5014464 DOI: 10.1038/mtna.2016.8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/08/2016] [Indexed: 12/12/2022]
Abstract
The advantages of lipid-based transfection reagents have permitted their widespread use in molecular biology and gene therapy. This study outlines the effect of cryo-manipulation of a cationic lipid-based formulation, Lipofectamine 2000, which, after being frozen and thawed, showed orders of magnitude higher plasmid delivery efficiency throughout eight different cell lines, without compromising cell viability. Increased transfection efficiency with the freeze-thawed reagent was also seen with 2'-O-methyl phosphorothioate oligonucleotide delivery and in a splice-correction assay. Most importantly, a log-scale improvement in gene delivery using the freeze-thawed reagent was seen in vivo. Using three different methods, we detected considerable differences in the polydispersity of the different nucleic acid complexes as well as observed a clear difference in their surface spreading and sedimentation, with the freeze-thawed ones displaying substantially higher rate of dispersion and deposition on the glass surface. This hitherto overlooked elevated potency of the freeze-thawed reagent facilitates the targeting of hard-to-transfect cells, accomplishes higher transfection rates, and decreases the overall amount of reagent needed for delivery. Additionally, as we also saw a slight increase in plasmid delivery using other freeze-thawed transfection reagents, we postulate that freeze-thawing might prove to be useful for an even wider variety of transfection reagents.
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26
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Duan D. Duchenne muscular dystrophy gene therapy in the canine model. HUM GENE THER CL DEV 2015; 26:57-69. [PMID: 25710459 PMCID: PMC4442571 DOI: 10.1089/humc.2015.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 01/13/2015] [Indexed: 12/12/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked lethal muscle disease caused by dystrophin deficiency. Gene therapy has significantly improved the outcome of dystrophin-deficient mice. Yet, clinical translation has not resulted in the expected benefits in human patients. This translational gap is largely because of the insufficient modeling of DMD in mice. Specifically, mice lacking dystrophin show minimum dystrophic symptoms, and they do not respond to the gene therapy vector in the same way as human patients do. Further, the size of a mouse is hundredfolds smaller than a boy, making it impossible to scale-up gene therapy in a mouse model. None of these limitations exist in the canine DMD (cDMD) model. For this reason, cDMD dogs have been considered a highly valuable platform to test experimental DMD gene therapy. Over the last three decades, a variety of gene therapy approaches have been evaluated in cDMD dogs using a number of nonviral and viral vectors. These studies have provided critical insight for the development of an effective gene therapy protocol in human patients. This review discusses the history, current status, and future directions of the DMD gene therapy in the canine model.
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Affiliation(s)
- Dongsheng Duan
- Department of Molecular Microbiology and Immunology, Department of Neurology School of Medicine, University of Missouri , Columbia, MO 65212
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27
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Localizing the RPGR protein along the cilium: a new method to determine efficacies to treat RPGR mutations. Gene Ther 2015; 22:413-20. [PMID: 25630948 DOI: 10.1038/gt.2014.128] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 01/18/2023]
Abstract
Retinal dystrophies constitute a group of clinically and genetically heterogeneous diseases that cause visual impairment. As treatments are not readily available, readout assays performed in patient-derived cells can aid in the development and comparative analysis of therapeutic approaches. We describe a new method with which the localization of the retinitis pigmentosa GTPase regulator (RPGR) protein along the cilium can be used as a measure for treatment efficacy. In a patient-derived fibroblast cell line, we found that the RPGR protein is mislocalized along the ciliary axoneme. The patient carried a point mutation that leads to skipping of RPGR exon 10. We confirmed that this skipping is causative for the impaired localization of RPGR using a U7 small nuclear RNA (U7snRNA)-based antisense approach in control cells. Treatment of the patient-derived fibroblasts with therapeutic U1snRNA significantly corrected the proteins' mislocalization. In this proof of principle study, we show that detecting the RPGR protein along the cilium provides a reliable and quantifiable readout assay to evaluate the efficacy of therapies intended to correct or silence RPGR gene mutations. This method opens the possibility to compare different therapeutic agents, and thus facilitate the identification of treatment options for the clinically and molecularly complex RPGR-associated diseases.
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Le Guiner C, Montus M, Servais L, Cherel Y, Francois V, Thibaud JL, Wary C, Matot B, Larcher T, Guigand L, Dutilleul M, Domenger C, Allais M, Beuvin M, Moraux A, Le Duff J, Devaux M, Jaulin N, Guilbaud M, Latournerie V, Veron P, Boutin S, Leborgne C, Desgue D, Deschamps JY, Moullec S, Fromes Y, Vulin A, Smith RH, Laroudie N, Barnay-Toutain F, Rivière C, Bucher S, Le TH, Delaunay N, Gasmi M, Kotin RM, Bonne G, Adjali O, Masurier C, Hogrel JY, Carlier P, Moullier P, Voit T. Forelimb treatment in a large cohort of dystrophic dogs supports delivery of a recombinant AAV for exon skipping in Duchenne patients. Mol Ther 2014; 22:1923-35. [PMID: 25200009 PMCID: PMC4429735 DOI: 10.1038/mt.2014.151] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 07/14/2014] [Indexed: 02/07/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disorder caused by mutations in the dystrophin gene, without curative treatment yet available. Our study provides, for the first time, the overall safety profile and therapeutic dose of a recombinant adeno-associated virus vector, serotype 8 (rAAV8) carrying a modified U7snRNA sequence promoting exon skipping to restore a functional in-frame dystrophin transcript, and injected by locoregional transvenous perfusion of the forelimb. Eighteen Golden Retriever Muscular Dystrophy (GRMD) dogs were exposed to increasing doses of GMP-manufactured vector. Treatment was well tolerated in all, and no acute nor delayed adverse effect, including systemic and immune toxicity was detected. There was a dose relationship for the amount of exon skipping with up to 80% of myofibers expressing dystrophin at the highest dose. Similarly, histological, nuclear magnetic resonance pathological indices and strength improvement responded in a dose-dependent manner. The systematic comparison of effects using different independent methods, allowed to define a minimum threshold of dystrophin expressing fibers (>33% for structural measures and >40% for strength) under which there was no clear-cut therapeutic effect. Altogether, these results support the concept of a phase 1/2 trial of locoregional delivery into upper limbs of nonambulatory DMD patients.
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Affiliation(s)
- Caroline Le Guiner
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
- Généthon, Evry, France
| | | | - Laurent Servais
- Institut de Myologie, Service of Clinical Trials and Databases, Paris, France
| | - Yan Cherel
- Atlantic Gene Therapies, INRA UMR 703, ONIRIS, Nantes, France
| | - Virginie Francois
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | - Jean-Laurent Thibaud
- Institut de Myologie, Laboratoire RMN, AIM & CEA, Paris, France
- UPR de Neurobiologie, Ecole Nationale Vétérinaire d'Alfort, Maisons Alfort, France
| | - Claire Wary
- Institut de Myologie, Laboratoire RMN, AIM & CEA, Paris, France
| | - Béatrice Matot
- Institut de Myologie, Laboratoire RMN, AIM & CEA, Paris, France
| | - Thibaut Larcher
- Atlantic Gene Therapies, INRA UMR 703, ONIRIS, Nantes, France
| | - Lydie Guigand
- Atlantic Gene Therapies, INRA UMR 703, ONIRIS, Nantes, France
| | - Maeva Dutilleul
- Atlantic Gene Therapies, INRA UMR 703, ONIRIS, Nantes, France
| | - Claire Domenger
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | - Marine Allais
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | - Maud Beuvin
- Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Université Pierre and Marie Curie Paris 6 UPMC-INSERM UMR 974, CNRS FRE 3617, Paris, France
| | - Amélie Moraux
- Institut de Myologie, Neuromuscular Physiology and Evaluation Laboratory, Paris, France
| | - Johanne Le Duff
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | - Marie Devaux
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | - Nicolas Jaulin
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | - Mickaël Guilbaud
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | | | | | | | | | | | - Jack-Yves Deschamps
- Atlantic Gene Therapies, INRA UMR 703, ONIRIS, Nantes, France
- Atlantic Gene Therapies, Centre de Boisbonne, ONIRIS, Nantes, France
| | - Sophie Moullec
- Atlantic Gene Therapies, Centre de Boisbonne, ONIRIS, Nantes, France
| | - Yves Fromes
- Atlantic Gene Therapies, Centre de Boisbonne, ONIRIS, Nantes, France
| | - Adeline Vulin
- Research Institute, Center for Gene Therapy, Nationwide Childrens Hospital, Columbus, Ohio, USA
| | - Richard H Smith
- Laboratory of Molecular Virology and Gene Therapy, National Heart Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, USA
| | | | | | | | | | | | | | | | - Robert M Kotin
- Laboratory of Molecular Virology and Gene Therapy, National Heart Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, USA
| | - Gisèle Bonne
- Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Université Pierre and Marie Curie Paris 6 UPMC-INSERM UMR 974, CNRS FRE 3617, Paris, France
- AP-HP, Groupe Hospitalier Pitié-Salpêtrière, U.F. Cardiogénétique et Myogénétique, Service de Biochimie Métabolique, Paris, France
| | - Oumeya Adjali
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
| | | | - Jean-Yves Hogrel
- Institut de Myologie, Neuromuscular Physiology and Evaluation Laboratory, Paris, France
| | - Pierre Carlier
- Institut de Myologie, Laboratoire RMN, AIM & CEA, Paris, France
| | - Philippe Moullier
- Atlantic Gene Therapies, INSERM UMR 1089, Université de Nantes, CHU de Nantes, Nantes, France
- Généthon, Evry, France
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA
| | - Thomas Voit
- Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Université Pierre and Marie Curie Paris 6 UPMC-INSERM UMR 974, CNRS FRE 3617, Paris, France
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Rendu J, Brocard J, Denarier E, Monnier N, Piétri-Rouxel F, Beley C, Roux-Buisson N, Gilbert-Dussardier B, Perez MJ, Romero N, Garcia L, Lunardi J, Fauré J, Fourest-Lieuvin A, Marty I. Exon skipping as a therapeutic strategy applied to an RYR1 mutation with pseudo-exon inclusion causing a severe core myopathy. Hum Gene Ther 2014; 24:702-13. [PMID: 23805838 DOI: 10.1089/hum.2013.052] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Central core disease is a myopathy often arising from mutations in the type 1 ryanodine receptor (RYR1) gene, encoding the sarcoplasmic reticulum calcium release channel RyR1. No treatment is currently available for this disease. We studied the pathological situation of a severely affected child with two recessive mutations, which resulted in a massive reduction in the amount of RyR1. The paternal mutation induced the inclusion of a new in-frame pseudo-exon in RyR1 mRNA that resulted in the insertion of additional amino acids leading to the instability of the protein. We hypothesized that skipping this additional exon would be sufficient to restore RyR1 expression and to normalize calcium releases. We therefore developed U7-AON lentiviral vectors to force exon skipping on affected primary muscle cells. The efficiency of the exon skipping was evaluated at the mRNA level, at the protein level, and at the functional level using calcium imaging. In these affected cells, we observed a decreased inclusion of the pseudo-exon, an increased RyR1 protein expression, and a restoration of calcium releases of normal amplitude either upon direct RyR1 stimulation or in response to membrane depolarization. This study is the first demonstration of the potential of exon-skipping strategy for the therapy of central core disease, from the molecular to the functional level.
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Affiliation(s)
- John Rendu
- INSERM U836, Grenoble Institut des Neurosciences, Equipe Muscle et Pathologies, 38000 Grenoble, France
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Abstract
β-thalassemia is an inherited disorder due to mutations found in the β-globin gene, leading to anemia and requiring sporadic or chronic blood transfusions for survival. Without proper chelation, β-thalassemia results in iron overload. Ineffective erythropoiesis can lead to iron overload even in untransfused patients who are affected by β-thalassemia intermedia. Better understanding of the molecular biologic aspects of this disorder has led to improvements in population screening and prenatal diagnosis, which, in turn, have led to dramatic reductions in the number of children born with β-thalassemia major in the Mediterranean littoral. However, as a consequence of decreases in neonatal and childhood mortality in other geographical areas, β-thalassemia has become a worldwide clinical problem. A number of unsolved pathophysiological issues remain, such as ineffective erythropoieis, abnormal iron absorption, oxidative stress, splenomegaly and thrombosis. In the last few years, novel studies have the potential to introduce new therapeutic approaches that might reduce these problems and limit the need for blood transfusion.
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Affiliation(s)
- Stefano Rivella
- Weill College Medical Center, Department of Pediatrics, Division of Hematology, Oncology, 515 E 71st Street, S702, New York, NY 10021, USA, Tel.: +1 212 746 4941, ,
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Micro-minicircle Gene Therapy: Implications of Size on Fermentation, Complexation, Shearing Resistance, and Expression. MOLECULAR THERAPY-NUCLEIC ACIDS 2014; 2:e140. [PMID: 24399204 PMCID: PMC3910003 DOI: 10.1038/mtna.2013.67] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/08/2013] [Indexed: 12/20/2022]
Abstract
The minicircle (MC), composed of eukaryotic sequences only, is an interesting approach to increase the safety and efficiency of plasmid-based vectors for gene therapy. In this paper, we investigate micro-MC (miMC) vectors encoding small regulatory RNA. We use a construct encoding a splice-correcting U7 small nuclear RNA, which results in a vector of 650 base pairs (bp), as compared to a conventional 3600 bp plasmid carrying the same expression cassette. Furthermore, we construct miMCs of varying sizes carrying different number of these cassettes. This allows us to evaluate how size influences production, super-coiling, stability and efficiency of the vector. We characterize coiling morphology by atomic force microscopy and measure the resistance to shearing forces caused by an injector device, the Biojector. We compare the behavior of miMCs and plasmids in vitro using lipofection and electroporation, as well as in vivo in mice. We here show that when the size of the miMC is reduced, the formation of dimers and trimers increases. There seems to be a lower size limit for efficient expression. We demonstrate that miMCs are more robust than plasmids when exposed to shearing forces, and that they show extended expression in vivo.
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Targeting the splicing of mRNA in autoimmune diseases: BAFF inhibition in Sjögren's syndrome as a proof of concept. Mol Ther 2013; 22:821-7. [PMID: 24304965 DOI: 10.1038/mt.2013.275] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 11/24/2013] [Indexed: 02/04/2023] Open
Abstract
BAFF (B-cell-activating factor of the tumor necrosis factor family), a pivotal cytokine for B-cell activation, is overexpressed by salivary gland (SG) epithelial cells in primary Sjogren's syndrome (pSS). ΔBAFF, a physiological inhibitor of BAFF, is a minor alternative splice variant of BAFF. A U7 RNA was reengineered to deliver antisense sequences targeting BAFF splice regions. A major decrease of BAFF messenger RNA (mRNA) and protein secretion, concomitantly with the increase of ΔBAFF mRNA, was observed in vitro. In vivo, SG retrograd instillation of nonobese diabetic mice by the modified U7 cloned into an adeno-associated virus vector significantly decreased BAFF protein expression and lymphocytic infiltrates and improved salivary flow. This study offers a rationale for localized therapeutic BAFF inhibition in pSS and represents a proof of concept of the interest of exon skipping in autoimmune diseases.
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Antisense-based RNA therapy of factor V deficiency: in vitro and ex vivo rescue of a F5 deep-intronic splicing mutation. Blood 2013; 122:3825-31. [DOI: 10.1182/blood-2013-04-499657] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Key Points
Homozygosity for the F5 c.1296+268A>G splicing mutation causes life-threatening factor V deficiency. Mutation-specific antisense molecules can correct this splicing defect and restore factor V synthesis in the patient’s megakaryocytes.
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34
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Lorain S, Peccate C, Le Hir M, Griffith G, Philippi S, Précigout G, Mamchaoui K, Jollet A, Voit T, Garcia L. Dystrophin rescue by trans-splicing: a strategy for DMD genotypes not eligible for exon skipping approaches. Nucleic Acids Res 2013; 41:8391-402. [PMID: 23861443 PMCID: PMC3783188 DOI: 10.1093/nar/gkt621] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
RNA-based therapeutic approaches using splice-switching oligonucleotides have been successfully applied to rescue dystrophin in Duchenne muscular dystrophy (DMD) preclinical models and are currently being evaluated in DMD patients. Although the modular structure of dystrophin protein tolerates internal deletions, many mutations that affect nondispensable domains of the protein require further strategies. Among these, trans-splicing technology is particularly attractive, as it allows the replacement of any mutated exon by its normal version as well as introducing missing exons or correcting duplication mutations. We have applied such a strategy in vitro by using cotransfection of pre–trans-splicing molecule (PTM) constructs along with a reporter minigene containing part of the dystrophin gene harboring the stop-codon mutation found in the mdx mouse model of DMD. Optimization of the different functional domains of the PTMs allowed achieving accurate and efficient trans-splicing of up to 30% of the transcript encoded by the cotransfected minigene. Optimized parameters included mRNA stabilization, choice of splice site sequence, inclusion of exon splice enhancers and artificial intronic sequence. Intramuscular delivery of adeno-associated virus vectors expressing PTMs allowed detectable levels of dystrophin in mdx and mdx4Cv, illustrating that a given PTM can be suitable for a variety of mutations.
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Affiliation(s)
- Stéphanie Lorain
- Thérapie des maladies du muscle strié, Um76 UPMC - UMR 7215 CNRS - U974 Inserm - Institut de Myologie, 75013 Paris, France and UFR des Sciences de la Santé, Université de Versailles Saint-Quentin-en-Yvelines, 78180 Montigny-le-Bretonneux, France
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35
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Barbash IM, Cecchini S, Faranesh AZ, Virag T, Li L, Yang Y, Hoyt RF, Kornegay JN, Bogan JR, Garcia L, Lederman RJ, Kotin RM. MRI roadmap-guided transendocardial delivery of exon-skipping recombinant adeno-associated virus restores dystrophin expression in a canine model of Duchenne muscular dystrophy. Gene Ther 2013; 20:274-82. [PMID: 22551778 PMCID: PMC3424392 DOI: 10.1038/gt.2012.38] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 03/29/2012] [Indexed: 01/16/2023]
Abstract
Duchenne muscular dystrophy (DMD) cardiomyopathy patients currently have no therapeutic options. We evaluated catheter-based transendocardial delivery of a recombinant adeno-associated virus (rAAV) expressing a small nuclear U7 RNA (U7smOPT) complementary to specific cis-acting splicing signals. Eliminating specific exons restores the open reading frame resulting in translation of truncated dystrophin protein. To test this approach in a clinically relevant DMD model, golden retriever muscular dystrophy (GRMD) dogs received serotype 6 rAAV-U7smOPT via the intracoronary or transendocardial route. Transendocardial injections were administered with an injection-tipped catheter and fluoroscopic guidance using X-ray fused with magnetic resonance imaging (XFM) roadmaps. Three months after treatment, tissues were analyzed for DNA, RNA, dystrophin protein, and histology. Whereas intracoronary delivery did not result in effective transduction, transendocardial injections, XFM guidance, enabled 30±10 non-overlapping injections per animal. Vector DNA was detectable in all samples tested and ranged from <1 to >3000 vector genome copies per cell. RNA analysis, western blot analysis, and immunohistology demonstrated extensive expression of skipped RNA and dystrophin protein in the treated myocardium. Left ventricular function remained unchanged over a 3-month follow-up. These results demonstrated that effective transendocardial delivery of rAAV-U7smOPT was achieved using XFM. This approach restores an open reading frame for dystrophin in affected dogs and has potential clinical utility.
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Affiliation(s)
- I M Barbash
- Cardiovascular and Pulmonary Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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Muscle function recovery in golden retriever muscular dystrophy after AAV1-U7 exon skipping. Mol Ther 2012; 20:2120-33. [PMID: 22968479 DOI: 10.1038/mt.2012.181] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder resulting from lesions of the gene encoding dystrophin. These usually consist of large genomic deletions, the extents of which are not correlated with the severity of the phenotype. Out-of-frame deletions give rise to dystrophin deficiency and severe DMD phenotypes, while internal deletions that produce in-frame mRNAs encoding truncated proteins can lead to a milder myopathy known as Becker muscular dystrophy (BMD). Widespread restoration of dystrophin expression via adeno-associated virus (AAV)-mediated exon skipping has been successfully demonstrated in the mdx mouse model and in cardiac muscle after percutaneous transendocardial delivery in the golden retriever muscular dystrophy dog (GRMD) model. Here, a set of optimized U7snRNAs carrying antisense sequences designed to rescue dystrophin were delivered into GRMD skeletal muscles by AAV1 gene transfer using intramuscular injection or forelimb perfusion. We show sustained correction of the dystrophic phenotype in extended muscle areas and partial recovery of muscle strength. Muscle architecture was improved and fibers displayed the hallmarks of mature and functional units. A 5-year follow-up ruled out immune rejection drawbacks but showed a progressive decline in the number of corrected muscle fibers, likely due to the persistence of a mild dystrophic process such as occurs in BMD phenotypes. Although AAV-mediated exon skipping was shown safe and efficient to rescue a truncated dystrophin, it appears that recurrent treatments would be required to maintain therapeutic benefit ahead of the progression of the disease.
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The Cellular Processing Capacity Limits the Amounts of Chimeric U7 snRNA Available for Antisense Delivery. MOLECULAR THERAPY. NUCLEIC ACIDS 2012; 1:e31. [PMID: 23344083 PMCID: PMC3390224 DOI: 10.1038/mtna.2012.24] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Many genetic diseases are induced by mutations disturbing the maturation of pre-mRNAs, often affecting splicing. Antisense oligoribonucleotides (AONs) have been used to modulate splicing thereby circumventing the deleterious effects of mutations. Stable delivery of antisense sequences is achieved by linking them to small nuclear RNA (snRNAs) delivered by viral vectors, as illustrated by studies where therapeutic exon skipping was obtained in animal models of Duchenne muscular dystrophy (DMD). Yet, clinical translation of these approaches is limited by the amounts of vector to be administered. In this respect, maximizing the amount of snRNA antisense shuttle delivered by the vector is essential. Here, we have used a muscle- and heart-specific enhancer (MHCK) to drive the expression of U7 snRNA shuttles carrying antisense sequences against the human or murine DMD pre-mRNAs. Although antisense delivery and subsequent exon skipping were improved both in tissue culture and in vivo, we observed the formation of additional U7 snRNA by-products following gene transfer. These included aberrantly 3′ processed as well as unprocessed species that may arise because of the saturation of the cellular processing capacity. Future efforts to increase the amounts of functional U7 shuttles delivered into a cell will have to take this limitation into account.
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Fernandez Alanis E, Pinotti M, Dal Mas A, Balestra D, Cavallari N, Rogalska ME, Bernardi F, Pagani F. An exon-specific U1 small nuclear RNA (snRNA) strategy to correct splicing defects. Hum Mol Genet 2012; 21:2389-98. [PMID: 22362925 PMCID: PMC3349419 DOI: 10.1093/hmg/dds045] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A significant proportion of disease-causing mutations affect precursor-mRNA splicing, inducing skipping of the exon from the mature transcript. Using F9 exon 5, CFTR exon 12 and SMN2 exon 7 models, we characterized natural mutations associated to exon skipping in Haemophilia B, cystic fibrosis and spinal muscular atrophy (SMA), respectively, and the therapeutic splicing rescue by using U1 small nuclear RNA (snRNA). In minigene expression systems, loading of U1 snRNA by complementarity to the normal or mutated donor splice sites (5′ss) corrected the exon skipping caused by mutations at the polypyrimidine tract of the acceptor splice site, at the consensus 5′ss or at exonic regulatory elements. To improve specificity and reduce potential off-target effects, we developed U1 snRNA variants targeting non-conserved intronic sequences downstream of the 5′ss. For each gene system, we identified an exon-specific U1 snRNA (ExSpeU1) able to rescue splicing impaired by the different types of mutations. Through splicing-competent cDNA constructs, we demonstrated that the ExSpeU1-mediated splicing correction of several F9 mutations results in complete restoration of secreted functional factor IX levels. Furthermore, two ExSpeU1s for SMA improved SMN exon 7 splicing in the chromosomal context of normal cells. We propose ExSpeU1s as a novel therapeutic strategy to correct, in several human disorders, different types of splicing mutations associated with defective exon definition.
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Affiliation(s)
- Eugenio Fernandez Alanis
- Human Molecular Genetics, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
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39
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Barrie ES, Smith RM, Sanford JC, Sadee W. mRNA transcript diversity creates new opportunities for pharmacological intervention. Mol Pharmacol 2012; 81:620-30. [PMID: 22319206 DOI: 10.1124/mol.111.076604] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Most protein coding genes generate multiple RNA transcripts through alternative splicing, variable 3' and 5'UTRs, and RNA editing. Although drug design typically targets the main transcript, alternative transcripts can have profound physiological effects, encoding proteins with distinct functions or regulatory properties. Formation of these alternative transcripts is tissue-selective and context-dependent, creating opportunities for more effective and targeted therapies with reduced adverse effects. Moreover, genetic variation can tilt the balance of alternative versus constitutive transcripts or generate aberrant transcripts that contribute to disease risk. In addition, environmental factors and drugs modulate RNA splicing, affording new opportunities for the treatment of splicing disorders. For example, therapies targeting specific mRNA transcripts with splice-site-directed oligonucleotides that correct aberrant splicing are already in clinical trials for genetic disorders such as Duchenne muscular dystrophy. High-throughput sequencing technologies facilitate discovery of novel RNA transcripts and protein isoforms, applications ranging from neuromuscular disorders to cancer. Consideration of a gene's transcript diversity should become an integral part of drug design, development, and therapy.
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Affiliation(s)
- Elizabeth S Barrie
- Program in Pharmacogenomics, Department of Pharmacology, The Ohio State University, Columbus, OH 43210, USA
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41
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Hammond SM, Wood MJA. Genetic therapies for RNA mis-splicing diseases. Trends Genet 2011; 27:196-205. [PMID: 21497936 DOI: 10.1016/j.tig.2011.02.004] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 02/08/2011] [Accepted: 02/11/2011] [Indexed: 02/07/2023]
Abstract
RNA mis-splicing diseases account for up to 15% of all inherited diseases, ranging from neurological to myogenic and metabolic disorders. With greatly increased genomic sequencing being performed for individual patients, the number of known mutations affecting splicing has risen to 50-60% of all disease-causing mutations. During the past 10years, genetic therapy directed toward correction of RNA mis-splicing in disease has progressed from theoretical work in cultured cells to promising clinical trials. In this review, we discuss the use of antisense oligonucleotides to modify splicing as well as the principles and latest work in bifunctional RNA, trans-splicing and modification of U1 and U7 snRNA to target splice sites. The success of clinical trials for modifying splicing to treat Duchenne muscular dystrophy opens the door for the use of splicing modification for most of the mis-splicing diseases.
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Affiliation(s)
- Suzan M Hammond
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK, OX1 3QX
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42
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Lu QL, Yokota T, Takeda S, Garcia L, Muntoni F, Partridge T. The status of exon skipping as a therapeutic approach to duchenne muscular dystrophy. Mol Ther 2010; 19:9-15. [PMID: 20978473 DOI: 10.1038/mt.2010.219] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is associated with mutations in the dystrophin gene that disrupt the open reading frame whereas the milder Becker's form is associated with mutations which leave an in-frame mRNA transcript that can be translated into a protein that includes the N- and C- terminal functional domains. It has been shown that by excluding specific exons at, or adjacent to, frame-shifting mutations, open reading frame can be restored to an out-of-frame mRNA, leading to the production of a partially functional Becker-like dystrophin protein. Such targeted exclusion can be achieved by administration of oligonucleotides that are complementary to sequences that are crucial to normal splicing of the exon into the transcript. This principle has been validated in mouse and canine models of DMD with a number of variants of oligonucleotide analogue chemistries and by transduction with adeno-associated virus (AAV)-small nuclear RNA (snRNA) reagents encoding the antisense sequence. Two different oligonucleotide agents are now being investigated in human trials for splicing out of exon 51 with some early indications of success at the biochemical level.
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Affiliation(s)
- Qi-Long Lu
- McColl-Lockwood Laboratory for Muscular Dystrophy Research, Neuromuscular/ALS Center, Carolinas Medical Center, Charlotte, North Carolina, USA
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Nlend Nlend R, Meyer K, Schümperli D. Repair of pre-mRNA splicing: prospects for a therapy for spinal muscular atrophy. RNA Biol 2010; 7:430-40. [PMID: 20523126 DOI: 10.4161/rna.7.4.12206] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Recent analyses of complete genomes have revealed that alternative splicing became more prevalent and important during eukaryotic evolution. Alternative splicing augments the protein repertoire--particularly that of the human genome--and plays an important role in the development and function of differentiated cell types. However, splicing is also extremely vulnerable, and defects in the proper recognition of splicing signals can give rise to a variety of diseases. In this review, we discuss splicing correction therapies, by using the inherited disease Spinal Muscular Atrophy (SMA) as an example. This lethal early childhood disorder is caused by deletions or other severe mutations of SMN1, a gene coding for the essential survival of motoneurons protein. A second gene copy present in humans and few non-human primates, SMN2, can only partly compensate for the defect because of a single nucleotide change in exon 7 that causes this exon to be skipped in the majority of mRNAs. Thus SMN2 is a prime therapeutic target for SMA. In recent years, several strategies based on small molecule drugs, antisense oligonucleotides or in vivo expressed RNAs have been developed that allow a correction of SMN2 splicing. For some of these, a therapeutic benefit has been demonstrated in mouse models for SMA. This means that clinical trials of such splicing therapies for SMA may become possible in the near future.
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Wein N, Avril A, Bartoli M, Beley C, Chaouch S, Laforêt P, Behin A, Butler-Browne G, Mouly V, Krahn M, Garcia L, Lévy N. Efficient bypass of mutations in dysferlin deficient patient cells by antisense-induced exon skipping. Hum Mutat 2010; 31:136-42. [PMID: 19953532 DOI: 10.1002/humu.21160] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mutations in DYSF encoding dysferlin cause primary dysferlinopathies, autosomal recessive diseases that mainly present clinically as Limb Girdle Muscular Dystrophy type 2B and Miyoshi myopathy. More than 350 different sequence variants have been reported in DYSF. Like dystrophin, the size of the dysferlin mRNA is above the limited packaging size of AAV vectors. Alternative strategies to AAV gene transfer in muscle cells must then be addressed for patients. A gene therapy approach for Duchenne muscular dystrophy was recently developed, based on exon-skipping strategy. Numerous sequences are recognized by splicing protein complexes and, when specifically blocked by antisense oligoucleotides (AON), the corresponding exon is skipped. We hypothesized that this approach could be useful for patients affected with dysferlinopathies. To confirm this assumption, exon 32 was selected as a prioritary target for exon skipping strategy. This option was initially driven by the report from Sinnreich and colleagues of a patient with a very mild and late-onset phenotype associated to a natural skipping of exon 32. Three different antisense oligonucleotides were tested in myoblasts generated from control and patient MyoD transduced fibroblasts, either as oligonucleotides or after incorporation into lentiviral vectors. These approaches led to a high efficiency of exon 32 skipping. Therefore, these results seem promising, and could be applied to several other exons in the DYSF gene. Patients carrying mutations in exons whose the in-frame suppression has been proven to have no major consequences on the protein function, might benefit of exon-skipping based gene correction.
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Affiliation(s)
- Nicolas Wein
- Université de la Méditerranée, Inserm UMR_S 910 Génétique Médicale et Génomique Fonctionnelle, Faculté de Médecine de Marseille, France
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Labie D, Kaplan JC. [Update on RNA splicing repair: applications to beta thalassemia and other perspectives]. Med Sci (Paris) 2010; 26:38-41. [PMID: 20132773 DOI: 10.1051/medsci/201026138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dhir A, Buratti E. Alternative splicing: role of pseudoexons in human disease and potential therapeutic strategies. FEBS J 2010; 277:841-55. [PMID: 20082636 DOI: 10.1111/j.1742-4658.2009.07520.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
What makes a nucleotide sequence an exon (or an intron) is a question that still lacks a satisfactory answer. Indeed, most eukaryotic genes are full of sequences that look like perfect exons, but which are nonetheless ignored by the splicing machinery (hence the name 'pseudoexons'). The existence of these pseudoexons has been known since the earliest days of splicing research, but until recently the tendency has been to view them as an interesting, but rather rare, curiosity. In recent years, however, the importance of pseudoexons in regulating splicing processes has been steadily revalued. Even more importantly, clinically oriented screening studies that search for splicing mutations are beginning to uncover a situation where aberrant pseudoexon inclusion as a cause of human disease is more frequent than previously thought. Here we aim to provide a review of the mechanisms that lead to pseudoexon activation in human genes and how the various cis- and trans-acting cellular factors regulate their inclusion. Moreover, we list the potential therapeutic approaches that are being tested with the aim of inhibiting their inclusion in the final mRNA molecules.
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Affiliation(s)
- Ashish Dhir
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
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Gene therapy in thalassemia and hemoglobinopathies. Mediterr J Hematol Infect Dis 2009; 1:e2009008. [PMID: 21415990 PMCID: PMC3033156 DOI: 10.4084/mjhid.2009.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Accepted: 11/12/2009] [Indexed: 01/19/2023] Open
Abstract
Sickle cell disease (SCD) and ß-thalassemia represent the most common hemoglobinopathies caused, respectively, by the alteration of structural features or deficient production of the ß-chain of the Hb molecule. Other hemoglobinopathies are characterized by different mutations in the α- or ß-globin genes and are associated with anemia and might require periodic or chronic blood transfusions. Therefore, ß-thalassemia, SCD and other hemoglobinopathies are excellent candidates for genetic approaches since they are monogenic disorders and, potentially, could be cured by introducing or correcting a single gene into the hematopoietic compartment or a single stem cell. Initial attempts at gene transfer of these hemoglobinopathies have proved unsuccessful due to limitations of available gene transfer vectors. With the advent of lentiviral vectors many of the initial limitations have been overcame. New approaches have also focused on targeting the specific mutation in the ß-globin genes, correcting the DNA sequence or manipulating the fate of RNA translation and splicing to restore ß-globin chain synthesis. These techniques have the potential to correct the defect into hematopoietic stem cells or be utilized to modify stem cells generated from patients affected by these disorders. This review discusses gene therapy strategies for the hemoglobinopathies, including the use of lentiviral vectors, generation of induced pluripotent stem cells (iPS) cells, gene targeting, splice-switching and stop codon readthrough.
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Virag T, Cecchini S, Kotin RM. Producing recombinant adeno-associated virus in foster cells: overcoming production limitations using a baculovirus-insect cell expression strategy. Hum Gene Ther 2009; 20:807-17. [PMID: 19604040 DOI: 10.1089/hum.2009.092] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Establishing pharmacological parameters, such as efficacy, routes of administration, and toxicity, for recombinant adeno-associated virus (rAAV) vectors is a prerequisite for gaining acceptance for clinical applications. In fact, even a therapeutic window, that is, the dose range between therapeutic efficacy and toxicity, has yet to be determined for rAAV in vivo. Multiphase clinical trials investigating the safety and efficacy of recombinant AAV-based therapeutics will require unprecedented vector production capacity to meet the needs of preclinical toxicology studies, and the progressive clinical protocol phases of safety/dose escalation (phase I), efficacy (phase II), and high-enrollment, multicenter evaluations (phase III). Methods of rAAV production capable of supporting such trials must be scalable, robust, and efficient. We have taken advantage of the ease of scalability of nonadherent cell culture techniques coupled with the inherent efficiency of viral infection to develop an rAAV production method based on recombinant baculovirus-mediated expression of AAV components in insect-derived suspension cells.
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Affiliation(s)
- Tamas Virag
- Molecular Virology and Gene Delivery Section, Laboratory of Biochemical Genetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Abstract
Our previous studies with genomic minigenes have demonstrated that an engineered small nuclear RNA-U1 (U1+5a) partially rescued coagulation factor VII (FVII) mRNA processing impaired by the 9726+5G>A mutation. Here, to evaluate the U1+5a effects on FVII function, we devised a full-length FVII splicing-competent construct (pSCFVII-wt). This construct drove in COS-1 cells the synthesis of properly processed FVII transcripts and of secreted functional FVII (23 ± 4 ng/mL), which were virtually undetectable upon introduction of the 9726+5G>A mutation (pSCFVII-9726+5a). Cotransfection of pSCFVII-9726+5a with pU1+5a resulted in a partial rescue of FVII splicing and protein biosynthesis. The level increase in medium was dose dependent and, with a molar excess (1.5×) of pU1+5a, reached 9.5% plus or minus 3.2% (5.0 ± 2.8 ng/mL) of FVII-wt coagulant activity. These data provide the first insights into the U1-snRNA–mediated rescue of donor splice sites at protein level, thus further highlighting its therapeutic implications in bleeding disorders, which would benefit even from tiny increase of functional levels.
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Du L, Gatti RA. Progress toward therapy with antisense-mediated splicing modulation. CURRENT OPINION IN MOLECULAR THERAPEUTICS 2009; 11:116-123. [PMID: 19330717 PMCID: PMC2753608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Antisense oligonucleotides (AO) or antisense RNA can complementarily bind to a target site in pre-mRNA and regulate gene splicing, either to restore gene function by reprogramming gene splicing or to inhibit gene expression by disrupting splicing. These two applications represent novel therapeutic strategies for several types of diseases such as genetic disorders, cancers and infectious diseases. In this review, the recent developments and applications of antisense-mediated splicing modulation in molecular therapy are discussed, with emphasis on advances in antisense-mediated splice targeting, applications in diseases and systematic delivery.
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Affiliation(s)
- Liutao Du
- Department of Pathology and Laboratory Medicine, The David Geffen School of Medicine at UCLA, 675 Charles Young Drive South, CA 90095-1732, USA.
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