1
|
Echigoya Y, Lim KRQ, Nakamura A, Yokota T. Multiple Exon Skipping in the Duchenne Muscular Dystrophy Hot Spots: Prospects and Challenges. J Pers Med 2018; 8:E41. [PMID: 30544634 DOI: 10.3390/jpm8040041] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 11/24/2018] [Accepted: 12/04/2018] [Indexed: 12/19/2022] Open
Abstract
Duchenne muscular dystrophy (DMD), a fatal X-linked recessive disorder, is caused mostly by frame-disrupting, out-of-frame deletions in the dystrophin (DMD) gene. Antisense oligonucleotide-mediated exon skipping is a promising therapy for DMD. Exon skipping aims to convert out-of-frame mRNA to in-frame mRNA and induce the production of internally-deleted dystrophin as seen in the less severe Becker muscular dystrophy. Currently, multiple exon skipping has gained special interest as a new therapeutic modality for this approach. Previous retrospective database studies represented a potential therapeutic application of multiple exon skipping. Since then, public DMD databases have become more useful with an increase in patient registration and advances in molecular diagnosis. Here, we provide an update on DMD genotype-phenotype associations using a global DMD database and further provide the rationale for multiple exon skipping development, particularly for exons 45–55 skipping and an emerging therapeutic concept, exons 3–9 skipping. Importantly, this review highlights the potential of multiple exon skipping for enabling the production of functionally-corrected dystrophin and for treating symptomatic patients not only with out-of-frame deletions but also those with in-frame deletions. We will also discuss prospects and challenges in multiple exon skipping therapy, referring to recent progress in antisense chemistry and design, as well as disease models.
Collapse
|
2
|
Lim KRQ, Echigoya Y, Nagata T, Kuraoka M, Kobayashi M, Aoki Y, Partridge T, Maruyama R, Takeda S, Yokota T. Efficacy of Multi-exon Skipping Treatment in Duchenne Muscular Dystrophy Dog Model Neonates. Mol Ther 2018; 27:76-86. [PMID: 30448197 DOI: 10.1016/j.ymthe.2018.10.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/14/2018] [Accepted: 10/16/2018] [Indexed: 12/12/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is caused by mutations in DMD, which codes for dystrophin. Because the progressive and irreversible degeneration of muscle occurs from childhood, earlier therapy is required to prevent dystrophic progression. Exon skipping by antisense oligonucleotides called phosphorodiamidate morpholino oligomers (PMOs), which restores the DMD reading frame and dystrophin expression, is a promising candidate for use in neonatal patients, yet the potential remains unclear. Here, we investigate the systemic efficacy and safety of early exon skipping in dystrophic dog neonates. Intravenous treatment of canine X-linked muscular dystrophy in Japan dogs with a 4-PMO cocktail resulted in ∼3%-27% in-frame exon 6-9 skipping and dystrophin restoration across skeletal muscles up to 14% of healthy levels. Histopathology was ameliorated with the reduction of fibrosis and/or necrosis area and centrally nucleated fibers, significantly in the diaphragm. Treatment induced cardiac multi-exon skipping, though dystrophin rescue was not detected. Functionally, treatment led to significant improvement in the standing test. Toxicity was not observed from blood tests. This is the first study to demonstrate successful multi-exon skipping treatment and significant functional improvement in dystrophic dogs. Early treatment was most beneficial for respiratory muscles, with implications for addressing pulmonary malfunction in patients.
Collapse
Affiliation(s)
- Kenji Rowel Q Lim
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G2H7, Canada
| | - Yusuke Echigoya
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G2H7, Canada; Laboratory of Biomedical Science, Department of Veterinary Medicine, Nihon University, Fujisawa, Kanagawa 252-0880, Japan
| | - Tetsuya Nagata
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - Mutsuki Kuraoka
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - Masanori Kobayashi
- Department of Reproduction, Nippon Veterinary and Life Science University, Musashino, Tokyo 180-0023, Japan
| | - Yoshitsugu Aoki
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - Terence Partridge
- Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC 20010, USA; Department of Integrative Systems Biology, George Washington University School of Medicine, Washington, DC 20010, USA
| | - Rika Maruyama
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G2H7, Canada
| | - Shin'ichi Takeda
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan.
| | - Toshifumi Yokota
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G2H7, Canada; Muscular Dystrophy Canada Research Chair, Edmonton, AB T6G2H7, Canada.
| |
Collapse
|
3
|
Suzuki H, Aoki Y, Kameyama T, Saito T, Masuda S, Tanihata J, Nagata T, Mayeda A, Takeda S, Tsukahara T. Endogenous Multiple Exon Skipping and Back-Splicing at the DMD Mutation Hotspot. Int J Mol Sci 2016; 17:ijms17101722. [PMID: 27754374 PMCID: PMC5085753 DOI: 10.3390/ijms17101722] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/26/2016] [Accepted: 09/30/2016] [Indexed: 12/15/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe muscular disorder. It was reported that multiple exon skipping (MES), targeting exon 45–55 of the DMD gene, might improve patients’ symptoms because patients who have a genomic deletion of all these exons showed very mild symptoms. Thus, exon 45–55 skipping treatments for DMD have been proposed as a potential clinical cure. Herein, we detected the expression of endogenous exons 44–56 connected mRNA transcript of the DMD using total RNAs derived from human normal skeletal muscle by reverse transcription polymerase chain reaction (RT-PCR), and identified a total of eight types of MES products around the hotspot. Surprisingly, the 5′ splice sites of recently reported post-transcriptional introns (remaining introns after co-transcriptional splicing) act as splicing donor sites for MESs. We also tested exon combinations to generate DMD circular RNAs (circRNAs) and determined the preferential splice sites of back-splicing, which are involved not only in circRNA generation, but also in MESs. Our results fit the current circRNA-generation model, suggesting that upstream post-transcriptional introns trigger MES and generate circRNA because its existence is critical for the intra-intronic interaction or for extremely distal splicing.
Collapse
Affiliation(s)
- Hitoshi Suzuki
- School of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1292, Japan.
| | - Yoshitsugu Aoki
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo 187-8502, Japan.
| | - Toshiki Kameyama
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.
| | - Takashi Saito
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo 187-8502, Japan.
| | - Satoru Masuda
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo 187-8502, Japan.
| | - Jun Tanihata
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo 187-8502, Japan.
| | - Tetsuya Nagata
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo 187-8502, Japan.
- Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyoku, Tokyo 113-0034, Japan.
| | - Akila Mayeda
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.
| | - Shin'ichi Takeda
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo 187-8502, Japan.
| | - Toshifumi Tsukahara
- School of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1292, Japan.
| |
Collapse
|