1
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Alves CRR, Ha LL, Yaworski R, Sutton ER, Lazzarotto CR, Christie KA, Reilly A, Beauvais A, Doll RM, de la Cruz D, Maguire CA, Swoboda KJ, Tsai SQ, Kothary R, Kleinstiver BP. Optimization of base editors for the functional correction of SMN2 as a treatment for spinal muscular atrophy. Nat Biomed Eng 2024; 8:118-131. [PMID: 38057426 PMCID: PMC10922509 DOI: 10.1038/s41551-023-01132-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 10/12/2023] [Indexed: 12/08/2023]
Abstract
Spinal muscular atrophy (SMA) is caused by mutations in SMN1. SMN2 is a paralogous gene with a C•G-to-T•A transition in exon 7, which causes this exon to be skipped in most SMN2 transcripts, and results in low levels of the protein survival motor neuron (SMN). Here we show, in fibroblasts derived from patients with SMA and in a mouse model of SMA that, irrespective of the mutations in SMN1, adenosine base editors can be optimized to target the SMN2 exon-7 mutation or nearby regulatory elements to restore the normal expression of SMN. After optimizing and testing more than 100 guide RNAs and base editors, and leveraging Cas9 variants with high editing fidelity that are tolerant of different protospacer-adjacent motifs, we achieved the reversion of the exon-7 mutation via an A•T-to-G•C edit in up to 99% of fibroblasts, with concomitant increases in the levels of the SMN2 exon-7 transcript and of SMN. Targeting the SMN2 exon-7 mutation via base editing or other CRISPR-based methods may provide long-lasting outcomes to patients with SMA.
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Affiliation(s)
- Christiano R R Alves
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.
- Department of Neurology, Harvard Medical School, Boston, MA, USA.
| | - Leillani L Ha
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
| | - Rebecca Yaworski
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Centre for Neuromuscular Disease, University of Ottawa, Ottawa, Ontario, Canada
| | - Emma R Sutton
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Centre for Neuromuscular Disease, University of Ottawa, Ottawa, Ontario, Canada
| | - Cicera R Lazzarotto
- Department of Hematology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Kathleen A Christie
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Harvard Medical School, Boston, MA, USA
| | - Aoife Reilly
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Centre for Neuromuscular Disease, University of Ottawa, Ottawa, Ontario, Canada
| | - Ariane Beauvais
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Centre for Neuromuscular Disease, University of Ottawa, Ottawa, Ontario, Canada
| | - Roman M Doll
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Molecular Biosciences/Cancer Biology Program, Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Demitri de la Cruz
- Molecular Neurogenetics Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
- Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Casey A Maguire
- Molecular Neurogenetics Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
- Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Kathryn J Swoboda
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Shengdar Q Tsai
- Department of Hematology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Rashmi Kothary
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Centre for Neuromuscular Disease, University of Ottawa, Ottawa, Ontario, Canada
- Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Benjamin P Kleinstiver
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA.
- Department of Pathology, Harvard Medical School, Boston, MA, USA.
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2
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Vlodavets DV. [Risdiplam for the treatment of spinal muscular atrophy]. Zh Nevrol Psikhiatr Im S S Korsakova 2024; 124:45-57. [PMID: 38465810 DOI: 10.17116/jnevro202412402145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Spinal muscular atrophy (SMA) is a devastating disease that is the leading genetic cause of death in infants and young children. It includes a broad spectrum of phenotypes that are classified into clinical groups based on the age of onset and maximum motor function achieved. The most common form of SMA is due to a defect in the survival motor neuron 1 gene (SMN1) localized to 5q11.2-q13.3. The development of clinical symptoms and disease progression is thought to be due to decreased levels of survival motor neuron (SMN) protein. SMA type 1 results in almost inevitable mortality within the first 2 years of life. The first two drugs approved globally for the treatment of SMA were the antisense oligonucleotide nusinersen (Spinraza), and the gene therapy onasemnogene abeparvovec-xioi (Zolgensma). Both interventions have approval and restrictions on use in different countries around the world. Despite these approved therapies, the medical unmet need in SMA (the majority of patients with SMA are not on a disease-modifying therapy) remains high with therapies in the pipeline to address some of the remaining limitations. The third and more recently approved drug for SMA is risdiplam (Evrysdi), an orally administered, centrally and peripherally distributed small molecule that modulates SMN2 pre-mRNA splicing toward the production of full-length SMN2 mRNA to increase functional SMN protein levels. In Russia the drug risdiplam was approved for use on November 26, 2020 with indications for the treatment of SMA in patients aged 2 months and older, and in 2023 the indications were expanded - use is allowed starting from the birth. Risdiplam is widely distributed into the CNS and peripheral tissues including muscles. Following risdiplam administration, SMN protein levels compared with baseline levels increase between 2- and 6-fold depending on the SMA phenotype treated. The risdiplam clinical development program currently has four ongoing clinical trials assessing its safety and efficacy. Clinical trials included more than 450 patients receiving risdiplam to date, has been well tolerated and no treatment-related safety findings leading to study withdrawal have been observed. Data from real clinical practice - more than 11.000 patients worldwide receive therapy with risdiplam, also confirm the safety and good tolerability of the drug.
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Affiliation(s)
- D V Vlodavets
- Veltischev Clinical Pediatric Research Institute of Pirogov Russian National Research Medical University, Moscow, Russia
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3
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Alves CRR, Ha LL, Yaworski R, Lazzarotto CR, Christie KA, Reilly A, Beauvais A, Doll RM, de la Cruz D, Maguire CA, Swoboda KJ, Tsai SQ, Kothary R, Kleinstiver BP. Base editing as a genetic treatment for spinal muscular atrophy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524978. [PMID: 36711797 PMCID: PMC9882371 DOI: 10.1101/2023.01.20.524978] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disease caused by mutations in the SMN1 gene. Despite the development of various therapies, outcomes can remain suboptimal in SMA infants and the duration of such therapies are uncertain. SMN2 is a paralogous gene that mainly differs from SMN1 by a C•G-to-T•A transition in exon 7, resulting in the skipping of exon 7 in most SMN2 transcripts and production of only low levels of survival motor neuron (SMN) protein. Genome editing technologies targeted to the SMN2 exon 7 mutation could offer a therapeutic strategy to restore SMN protein expression to normal levels irrespective of the patient SMN1 mutation. Here, we optimized a base editing approach to precisely edit SMN2, reverting the exon 7 mutation via an A•T-to-G•C base edit. We tested a range of different adenosine base editors (ABEs) and Cas9 enzymes, resulting in up to 99% intended editing in SMA patient-derived fibroblasts with concomitant increases in SMN2 exon 7 transcript expression and SMN protein levels. We generated and characterized ABEs fused to high-fidelity Cas9 variants which reduced potential off-target editing. Delivery of these optimized ABEs via dual adeno-associated virus (AAV) vectors resulted in precise SMN2 editing in vivo in an SMA mouse model. This base editing approach to correct SMN2 should provide a long-lasting genetic treatment for SMA with advantages compared to current nucleic acid, small molecule, or exogenous gene replacement therapies. More broadly, our work highlights the potential of PAMless SpRY base editors to install edits efficiently and safely.
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Affiliation(s)
- Christiano R. R. Alves
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Leillani L. Ha
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
| | - Rebecca Yaworski
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, ON, Canada
- Centre for Neuromuscular Disease, University of Ottawa, ON, Canada
| | - Cicera R. Lazzarotto
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Kathleen A. Christie
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Harvard Medical School, Boston, MA, USA
| | - Aoife Reilly
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, ON, Canada
- Centre for Neuromuscular Disease, University of Ottawa, ON, Canada
| | - Ariane Beauvais
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, ON, Canada
- Centre for Neuromuscular Disease, University of Ottawa, ON, Canada
| | - Roman M. Doll
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Molecular Biosciences/Cancer Biology Program, Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Demitri de la Cruz
- Molecular Neurogenetics Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
- Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Casey A. Maguire
- Molecular Neurogenetics Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
- Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Kathryn J. Swoboda
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Shengdar Q. Tsai
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Rashmi Kothary
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, ON, Canada
- Centre for Neuromuscular Disease, University of Ottawa, ON, Canada
- Department of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Benjamin P. Kleinstiver
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Harvard Medical School, Boston, MA, USA
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4
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Abstract
Spinal muscular atrophy (SMA) is caused by biallelic mutations in the SMN1 (survival motor neuron 1) gene on chromosome 5q13.2, which leads to a progressive degeneration of alpha motor neurons in the spinal cord and in motor nerve nuclei in the caudal brainstem. It is characterized by progressive proximally accentuated muscle weakness with loss of already acquired motor skills, areflexia and, depending on the phenotype, varying degrees of weakness of the respiratory and bulbar muscles. Over the past decade, disease-modifying therapies have become available based on splicing modulation of the SMN2 with SMN1 gene replacement, which if initiated significantly modifies the natural course of the disease. Newborn screening for SMA has been implemented in an increasing number of centers; however, available evidence for these new treatments is often limited to a small spectrum of patients concerning age and disease stage.
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Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
| | - Jerry R Mendell
- Department of Neurology and Pediatrics, Center for Gene Therapy, Abigail Wexner Research Institute, The Ohio State University, Nationwide Children's Hospital, Columbus, OH, United States
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5
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Younger DS. Neurogenetic motor disorders. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:183-250. [PMID: 37562870 DOI: 10.1016/b978-0-323-98818-6.00003-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Advances in the field of neurogenetics have practical applications in rapid diagnosis on blood and body fluids to extract DNA, obviating the need for invasive investigations. The ability to obtain a presymptomatic diagnosis through genetic screening and biomarkers can be a guide to life-saving disease-modifying therapy or enzyme replacement therapy to compensate for the deficient disease-causing enzyme. The benefits of a comprehensive neurogenetic evaluation extend to family members in whom identification of the causal gene defect ensures carrier detection and at-risk counseling for future generations. This chapter explores the many facets of the neurogenetic evaluation in adult and pediatric motor disorders as a primer for later chapters in this volume and a roadmap for the future applications of genetics in neurology.
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Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
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6
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Autophagy regulation by RNA alternative splicing and implications in human diseases. Nat Commun 2022; 13:2735. [PMID: 35585060 PMCID: PMC9117662 DOI: 10.1038/s41467-022-30433-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 04/29/2022] [Indexed: 02/06/2023] Open
Abstract
Autophagy and RNA alternative splicing are two evolutionarily conserved processes involved in overlapping physiological and pathological processes. However, the extent of functional connection is not well defined. Here, we consider the role for alternative splicing and generation of autophagy-related gene isoforms in the regulation of autophagy in recent work. The impact of changes to the RNA alternative splicing machinery and production of alternative spliced isoforms on autophagy are reviewed with particular focus on disease relevance. The use of drugs targeting both alternative splicing and autophagy as well as the selective regulation of single autophagy-related protein isoforms, are considered as therapeutic strategies. Both alternative splicing and autophagy are core cell biological processes, but where they intersect has received little attention. Here, the authors reflect on recent connections identified between these pathways and consider their impact on human disease.
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7
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Kray KM, McGovern VL, Chugh D, Arnold WD, Burghes AHM. Dual SMN inducing therapies can rescue survival and motor unit function in symptomatic ∆7SMA mice. Neurobiol Dis 2021; 159:105488. [PMID: 34425216 PMCID: PMC8502210 DOI: 10.1016/j.nbd.2021.105488] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/06/2021] [Accepted: 08/16/2021] [Indexed: 11/24/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by survival motor neuron (SMN) protein deficiency which results in motor neuron loss and muscle atrophy. SMA is caused by a mutation or deletion of the survival motor neuron 1 (SMN1) gene and retention of the nearly identical SMN2 gene. SMN2 contains a C to T change in exon 7 that results in exon 7 exclusion from 90% of transcripts. SMN protein lacking exon 7 is unstable and rapidly degraded. The remaining full-length transcripts from SMN2 are insufficient for normal motor neuron function leading to the development of SMA. Three different therapeutic approaches that increase full-length SMN (FL-SMN) protein production are approved for treatment of SMA patients. Studies in both animal models and humans have demonstrated increasing SMN levels prior to onset of symptoms provides the greatest therapeutic benefit. Treatment of SMA, after some motor neuron loss has occurred, is also effective but to a lesser degree. The SMN∆7 mouse model is a well characterized model of severe or type 1 SMA, dying at 14 days of age. Here we treated three groups of ∆7SMA mice starting before, roughly during, and after symptom onset to determine if combining two mechanistically distinct SMN inducing therapies could improve the therapeutic outcome both before and after motor neuron loss. We found, compared with individual therapies, that morpholino antisense oligonucleotide (ASO) directed against ISS-N1 combined with the small molecule compound RG7800 significantly increased FL-SMN transcript and protein production resulting in improved survival and weight of ∆7SMA mice. Moreover, when give late symptomatically, motor unit function was completely rescued with no loss in function at 100 days of age in the dual treatment group. We have therefore shown that this dual therapeutic approach successfully increases SMN protein and rescues motor function in symptomatic ∆7SMA mice.
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Affiliation(s)
- Kaitlyn M Kray
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA.
| | - Vicki L McGovern
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA.
| | - Deepti Chugh
- Department of Neurology, Neuromuscular Division, The Ohio State University Wexner Medical Center, 395 W. 12(th) Ave, Columbus, OH 43210, USA
| | - W David Arnold
- Department of Neurology, Neuromuscular Division, The Ohio State University Wexner Medical Center, 395 W. 12(th) Ave, Columbus, OH 43210, USA.
| | - Arthur H M Burghes
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA; Department of Neurology, Neuromuscular Division, The Ohio State University Wexner Medical Center, 395 W. 12(th) Ave, Columbus, OH 43210, USA.
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8
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Alternative Splicing Role in New Therapies of Spinal Muscular Atrophy. Genes (Basel) 2021; 12:genes12091346. [PMID: 34573328 PMCID: PMC8468182 DOI: 10.3390/genes12091346] [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: 07/29/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/17/2022] Open
Abstract
It has been estimated that 80% of the pre-mRNA undergoes alternative splicing, which exponentially increases the flow of biological information in cellular processes and can be an attractive therapeutic target. It is a crucial mechanism to increase genetic diversity. Disturbed alternative splicing is observed in many disorders, including neuromuscular diseases and carcinomas. Spinal Muscular Atrophy (SMA) is an autosomal recessive neurodegenerative disease. Homozygous deletion in 5q13 (the region coding for the motor neuron survival gene (SMN1)) is responsible for 95% of SMA cases. The nearly identical SMN2 gene does not compensate for SMN loss caused by SMN1 gene mutation due to different splicing of exon 7. A pathologically low level of survival motor neuron protein (SMN) causes degeneration of the anterior horn cells in the spinal cord with associated destruction of α-motor cells and manifested by muscle weakness and loss. Understanding the regulation of the SMN2 pre-mRNA splicing process has allowed for innovative treatment and the introduction of new medicines for SMA. After describing the concept of splicing modulation, this review will cover the progress achieved in this field, by highlighting the breakthrough accomplished recently for the treatment of SMA using the mechanism of alternative splicing.
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9
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Zhao X, Feng Z, Risher N, Mollin A, Sheedy J, Ling KKY, Narasimhan J, Dakka A, Baird JD, Ratni H, Lutz C, Chen K, Naryshkin N, Ko CP, Welch E, Metzger F, Weetall M. SMN protein is required throughout life to prevent spinal muscular atrophy disease progression. Hum Mol Genet 2021; 31:82-96. [PMID: 34368854 DOI: 10.1093/hmg/ddab220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/19/2021] [Accepted: 07/22/2021] [Indexed: 11/12/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by the loss of the survival motor neuron 1 (SMN1) gene function. The related SMN2 gene partially compensates but produces insufficient levels of SMN protein due to alternative splicing of exon 7. Evrysdi™ (risdiplam), recently approved for the treatment of SMA, and related compounds promote exon 7 inclusion to generate full-length SMN2 mRNA and increase SMN protein levels. SMNΔ7 type I SMA mice survive without treatment for ~ 17 days. SMN2 mRNA splicing modulators increase survival of SMN∆7 mice with treatment initiated at postnatal day 3 (PND3). To define SMN requirements for adult mice, SMNΔ7 mice were dosed with a SMN2 mRNA splicing modifier from PND3 to PND40, then dosing was stopped. Mice not treated after PND40 showed progressive weight loss, necrosis, and muscle atrophy after ~ 20 days. Male mice presented a more severe phenotype than female mice. Mice dosed continuously did not show disease symptoms. The estimated half-life of SMN protein is 2 days indicating that the SMA phenotype reappeared after SMN protein levels returned to baseline. Although SMN protein levels decreased with age in mice and SMN protein levels were higher in brain than in muscle, our studies suggest that SMN protein is required throughout the life of the mouse and is especially essential in adult peripheral tissues including muscle. These studies indicate that drugs such as risdiplam will be optimally therapeutic when given as early as possible after diagnosis and potentially will be required for the life of an SMA patient.
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Affiliation(s)
- Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Zhihua Feng
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Nicole Risher
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Anna Mollin
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | - Karen K Y Ling
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | | | - Amal Dakka
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - John D Baird
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Hasane Ratni
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | | | | | | | - Chien-Ping Ko
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Ellen Welch
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Friedrich Metzger
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
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10
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Activation of Muscle-Specific Kinase (MuSK) Reduces Neuromuscular Defects in the Delta7 Mouse Model of Spinal Muscular Atrophy (SMA). Int J Mol Sci 2021; 22:ijms22158015. [PMID: 34360794 PMCID: PMC8348537 DOI: 10.3390/ijms22158015] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 02/07/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease caused by insufficient levels of the survival motor neuron (SMN) protein. One of the most prominent pathological characteristics of SMA involves defects of the neuromuscular junction (NMJ), such as denervation and reduced clustering of acetylcholine receptors (AChRs). Recent studies suggest that upregulation of agrin, a crucial NMJ organizer promoting AChR clustering, can improve NMJ innervation and reduce muscle atrophy in the delta7 mouse model of SMA. To test whether the muscle-specific kinase (MuSK), part of the agrin receptor complex, also plays a beneficial role in SMA, we treated the delta7 SMA mice with an agonist antibody to MuSK. MuSK agonist antibody #13, which binds to the NMJ, significantly improved innervation and synaptic efficacy in denervation-vulnerable muscles. MuSK agonist antibody #13 also significantly increased the muscle cross-sectional area and myofiber numbers in these denervation-vulnerable muscles but not in denervation-resistant muscles. Although MuSK agonist antibody #13 did not affect the body weight, our study suggests that preservation of NMJ innervation by the activation of MuSK may serve as a complementary therapy to SMN-enhancing drugs to maximize the therapeutic effectiveness for all types of SMA patients.
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11
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Weissman AS, Kennedy KR, Powell MR, Davis LS. Skin necrosis in spinal muscular atrophy: Case report and review of the literature. Pediatr Dermatol 2021; 38:632-636. [PMID: 33619801 DOI: 10.1111/pde.14538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 01/11/2021] [Accepted: 01/21/2021] [Indexed: 11/29/2022]
Abstract
Spinal muscular atrophy (SMA) type 0 is the most severe phenotype of SMA and is characterized by hypotonia, muscle weakness, and respiratory distress. Cutaneous necrosis, first described in an SMA mouse model, can occur in patients with severe disease; the use of targeted treatment versus supportive measures in the setting of skin necrosis is debated. We present a male infant with SMA type 0 with cutaneous necrosis of proximal and distal limbs who improved with supportive care. The seven previously reported cases of SMA skin necrosis are reviewed.
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Affiliation(s)
| | - Kelsey R Kennedy
- Department of Dermatology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Matthew R Powell
- Department of Pathology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Loretta S Davis
- Department of Dermatology, Medical College of Georgia, Augusta University, Augusta, GA, USA
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12
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Migazzi A, Scaramuzzino C, Anderson EN, Tripathy D, Hernández IH, Grant RA, Roccuzzo M, Tosatto L, Virlogeux A, Zuccato C, Caricasole A, Ratovitski T, Ross CA, Pandey UB, Lucas JJ, Saudou F, Pennuto M, Basso M. Huntingtin-mediated axonal transport requires arginine methylation by PRMT6. Cell Rep 2021; 35:108980. [PMID: 33852844 PMCID: PMC8132453 DOI: 10.1016/j.celrep.2021.108980] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/09/2021] [Accepted: 03/23/2021] [Indexed: 12/24/2022] Open
Abstract
The huntingtin (HTT) protein transports various organelles, including vesicles containing neurotrophic factors, from embryonic development throughout life. To better understand how HTT mediates axonal transport and why this function is disrupted in Huntington's disease (HD), we study vesicle-associated HTT and find that it is dimethylated at a highly conserved arginine residue (R118) by the protein arginine methyltransferase 6 (PRMT6). Without R118 methylation, HTT associates less with vesicles, anterograde trafficking is diminished, and neuronal death ensues-very similar to what occurs in HD. Inhibiting PRMT6 in HD cells and neurons exacerbates mutant HTT (mHTT) toxicity and impairs axonal trafficking, whereas overexpressing PRMT6 restores axonal transport and neuronal viability, except in the presence of a methylation-defective variant of mHTT. In HD flies, overexpressing PRMT6 rescues axonal defects and eclosion. Arginine methylation thus regulates HTT-mediated vesicular transport along the axon, and increasing HTT methylation could be of therapeutic interest for HD.
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Affiliation(s)
- Alice Migazzi
- Laboratory of Transcriptional Neurobiology, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento 38123, Italy; Dulbecco Telethon Institute, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento 38123, Italy; Department of Biomedical Sciences (DBS), University of Padova, Padova 35131, Italy
| | - Chiara Scaramuzzino
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, GIN, Grenoble 38000, France
| | - Eric N Anderson
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA
| | - Debasmita Tripathy
- Laboratory of Transcriptional Neurobiology, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento 38123, Italy
| | - Ivó H Hernández
- Centro de Biología Molecular "Severo Ochoa" (CBMSO) CSIC/UAM, Madrid, Spain; Networking Research Center on Neurodegenerative Diseases (CIBERNED), Instituto de Salud Carlos III, Madrid 28029, Spain
| | - Rogan A Grant
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA
| | - Michela Roccuzzo
- Advanced Imaging Core Facility, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento 38123, Italy
| | - Laura Tosatto
- Institute of Biophysics, National Research Council (CNR) Trento unit, Trento 38123, Italy
| | - Amandine Virlogeux
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, GIN, Grenoble 38000, France
| | - Chiara Zuccato
- Department of Biosciences, University of Milan, Milan, Italy; Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi," Milan 20122, Italy
| | | | - Tamara Ratovitski
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Christopher A Ross
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Udai B Pandey
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA
| | - José J Lucas
- Centro de Biología Molecular "Severo Ochoa" (CBMSO) CSIC/UAM, Madrid, Spain; Networking Research Center on Neurodegenerative Diseases (CIBERNED), Instituto de Salud Carlos III, Madrid 28029, Spain
| | - Frédéric Saudou
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, GIN, Grenoble 38000, France.
| | - Maria Pennuto
- Dulbecco Telethon Institute, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento 38123, Italy; Department of Biomedical Sciences (DBS), University of Padova, Padova 35131, Italy; Veneto Institute of Molecular Medicine (VIMM), via Orus 2, Padova 35129, Italy; Padova Neuroscience Center (PNC), Padova 35131, Italy; Myology Center (CIR-Myo), Padova 35131, Italy.
| | - Manuela Basso
- Laboratory of Transcriptional Neurobiology, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento 38123, Italy.
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13
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Brenner D, Ludolph AC, Weishaupt JH. Gene specific therapies - the next therapeutic milestone in neurology. Neurol Res Pract 2020; 2:25. [PMID: 33324928 PMCID: PMC7650126 DOI: 10.1186/s42466-020-00075-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023] Open
Abstract
Gene selective approaches that either correct a disease mutation or a pathogenic mechanism will fundamentally change the treatment of neurological disorders. Basically, gene specific therapies are designed to manipulate RNA expression or reconstitute gene expression and function depending on the disease mechanism. Considerable methodological advances in the last years have made successful clinical translation of gene selective approaches possible, based on RNA interference or viral gene reconstitution in spinal muscular atrophy (SMA), Duchenne muscular dystrophy (DMD), and familial amyloid polyneuropathy (FAP). In this review, we provide an overview of the existing and coming gene specific therapies in neurology and discuss benefits, risks and challenges.
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Affiliation(s)
- David Brenner
- Department of Neurology, University of Ulm, Ulm, Germany
- Division of Neurodegenerative Diseases, Neurology Department, University Medicine Mannheim, Mannheim, Germany
| | - Albert C. Ludolph
- Department of Neurology, University of Ulm, Ulm, Germany
- German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany
| | - Jochen H. Weishaupt
- Department of Neurology, University of Ulm, Ulm, Germany
- Division of Neurodegenerative Diseases, Neurology Department, University Medicine Mannheim, Mannheim, Germany
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14
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Osman EY, Van Alstyne M, Yen PF, Lotti F, Feng Z, Ling KK, Ko CP, Pellizzoni L, Lorson CL. Minor snRNA gene delivery improves the loss of proprioceptive synapses on SMA motor neurons. JCI Insight 2020; 5:130574. [PMID: 32516136 DOI: 10.1172/jci.insight.130574] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 05/13/2020] [Indexed: 12/17/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an inherited neuromuscular disorder caused by reduced expression of the survival motor neuron (SMN) protein. SMN has key functions in multiple RNA pathways, including the biogenesis of small nuclear ribonucleoproteins that are essential components of both major (U2-dependent) and minor (U12-dependent) spliceosomes. Here we investigated the specific contribution of U12 splicing dysfunction to SMA pathology through selective restoration of this RNA pathway in mouse models of varying phenotypic severity. We show that virus-mediated delivery of minor snRNA genes specifically improves select U12 splicing defects induced by SMN deficiency in cultured mammalian cells, as well as in the spinal cord and dorsal root ganglia of SMA mice without increasing SMN expression. This approach resulted in a moderate amelioration of several parameters of the disease phenotype in SMA mice, including survival, weight gain, and motor function. Importantly, minor snRNA gene delivery improved aberrant splicing of the U12 intron-containing gene Stasimon and rescued the severe loss of proprioceptive sensory synapses on SMA motor neurons, which are early signatures of motor circuit dysfunction in mouse models. Taken together, these findings establish the direct contribution of U12 splicing dysfunction to synaptic deafferentation and motor circuit pathology in SMA.
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Affiliation(s)
- Erkan Y Osman
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Meaghan Van Alstyne
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Pei-Fen Yen
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Francesco Lotti
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Zhihua Feng
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Karen Ky Ling
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Chien-Ping Ko
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Christian L Lorson
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
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15
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RNA-Targeted Therapies and High-Throughput Screening Methods. Int J Mol Sci 2020; 21:ijms21082996. [PMID: 32340368 PMCID: PMC7216119 DOI: 10.3390/ijms21082996] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 02/07/2023] Open
Abstract
RNA-binding proteins (RBPs) are involved in regulating all aspects of RNA metabolism, including processing, transport, translation, and degradation. Dysregulation of RNA metabolism is linked to a plethora of diseases, such as cancer, neurodegenerative diseases, and neuromuscular disorders. Recent years have seen a dramatic shift in the knowledge base, with RNA increasingly being recognised as an attractive target for precision medicine therapies. In this article, we are going to review current RNA-targeted therapies. Furthermore, we will scrutinise a range of drug discoveries targeting protein-RNA interactions. In particular, we will focus on the interplay between Lin28 and let-7, splicing regulatory proteins and survival motor neuron (SMN) pre-mRNA, as well as HuR, Musashi, proteins and their RNA targets. We will highlight the mechanisms RBPs utilise to modulate RNA metabolism and discuss current high-throughput screening strategies. This review provides evidence that we are entering a new era of RNA-targeted medicine.
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16
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Long KK, O’Shea KM, Khairallah RJ, Howell K, Paushkin S, Chen KS, Cote SM, Webster MT, Stains JP, Treece E, Buckler A, Donovan A. Specific inhibition of myostatin activation is beneficial in mouse models of SMA therapy. Hum Mol Genet 2019; 28:1076-1089. [PMID: 30481286 PMCID: PMC6423420 DOI: 10.1093/hmg/ddy382] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 12/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disease characterized by loss of α-motor neurons, leading to profound skeletal muscle atrophy. Patients also suffer from decreased bone mineral density and increased fracture risk. The majority of treatments for SMA, approved or in clinic trials, focus on addressing the underlying cause of disease, insufficient production of full-length SMN protein. While restoration of SMN has resulted in improvements in functional measures, significant deficits remain in both mice and SMA patients following treatment. Motor function in SMA patients may be additionally improved by targeting skeletal muscle to reduce atrophy and improve muscle strength. Inhibition of myostatin, a negative regulator of muscle mass, offers a promising approach to increase muscle function in SMA patients. Here we demonstrate that muSRK-015P, a monoclonal antibody which specifically inhibits myostatin activation, effectively increases muscle mass and function in two variants of the pharmacological mouse model of SMA in which pharmacologic restoration of SMN has taken place either 1 or 24 days after birth to reflect early or later therapeutic intervention. Additionally, muSRK-015P treatment improves the cortical and trabecular bone phenotypes in these mice. These data indicate that preventing myostatin activation has therapeutic potential in addressing muscle and bone deficiencies in SMA patients. An optimized variant of SRK-015P, SRK-015, is currently in clinical development for treatment of SMA.
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Affiliation(s)
| | | | | | - Kelly Howell
- SMA Foundation, 888 7th Avenue #400, New York, NY
| | | | - Karen S Chen
- SMA Foundation, 888 7th Avenue #400, New York, NY
| | - Shaun M Cote
- Scholar Rock Inc., 620 Memorial Drive, Cambridge, MA
| | | | - Joseph P Stains
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Erin Treece
- Scholar Rock Inc., 620 Memorial Drive, Cambridge, MA
| | - Alan Buckler
- Scholar Rock Inc., 620 Memorial Drive, Cambridge, MA
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17
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Poirier A, Weetall M, Heinig K, Bucheli F, Schoenlein K, Alsenz J, Bassett S, Ullah M, Senn C, Ratni H, Naryshkin N, Paushkin S, Mueller L. Risdiplam distributes and increases SMN protein in both the central nervous system and peripheral organs. Pharmacol Res Perspect 2018; 6:e00447. [PMID: 30519476 PMCID: PMC6262736 DOI: 10.1002/prp2.447] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 10/29/2018] [Accepted: 10/29/2018] [Indexed: 12/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a rare, inherited neuromuscular disease caused by deletion and/or mutation of the Survival of Motor Neuron 1 (SMN1) gene. A second gene, SMN2, produces low levels of functional SMN protein that are insufficient to fully compensate for the lack of SMN1. Risdiplam (RG7916; RO7034067) is an orally administered, small-molecule SMN2 pre-mRNA splicing modifier that distributes into the central nervous system (CNS) and peripheral tissues. To further explore risdiplam distribution, we assessed in vitro characteristics and in vivo drug levels and effect of risdiplam on SMN protein expression in different tissues in animal models. Total drug levels were similar in plasma, muscle, and brain of mice (n = 90), rats (n = 148), and monkeys (n = 24). As expected mechanistically based on its high passive permeability and not being a human multidrug resistance protein 1 substrate, risdiplam CSF levels reflected free compound concentration in plasma in monkeys. Tissue distribution remained unchanged when monkeys received risdiplam once daily for 39 weeks. A parallel dose-dependent increase in SMN protein levels was seen in CNS and peripheral tissues in two SMA mouse models dosed with risdiplam. These in vitro and in vivo preclinical data strongly suggest that functional SMN protein increases seen in patients' blood following risdiplam treatment should reflect similar increases in functional SMN protein in the CNS, muscle, and other peripheral tissues.
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Affiliation(s)
- Agnès Poirier
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | | | - Katja Heinig
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | - Franz Bucheli
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | - Kerstin Schoenlein
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | - Jochem Alsenz
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | - Simon Bassett
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | - Mohammed Ullah
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | - Claudia Senn
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | - Hasane Ratni
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
| | | | | | - Lutz Mueller
- Roche Pharma Research and Early DevelopmentRoche Innovation CenterBaselSwitzerland
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18
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Dowling JJ, D. Gonorazky H, Cohn RD, Campbell C. Treating pediatric neuromuscular disorders: The future is now. Am J Med Genet A 2018; 176:804-841. [PMID: 28889642 PMCID: PMC5900978 DOI: 10.1002/ajmg.a.38418] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/12/2022]
Abstract
Pediatric neuromuscular diseases encompass all disorders with onset in childhood and where the primary area of pathology is in the peripheral nervous system. These conditions are largely genetic in etiology, and only those with a genetic underpinning will be presented in this review. This includes disorders of the anterior horn cell (e.g., spinal muscular atrophy), peripheral nerve (e.g., Charcot-Marie-Tooth disease), the neuromuscular junction (e.g., congenital myasthenic syndrome), and the muscle (myopathies and muscular dystrophies). Historically, pediatric neuromuscular disorders have uniformly been considered to be without treatment possibilities and to have dire prognoses. This perception has gradually changed, starting in part with the discovery and widespread application of corticosteroids for Duchenne muscular dystrophy. At present, several exciting therapeutic avenues are under investigation for a range of conditions, offering the potential for significant improvements in patient morbidities and mortality and, in some cases, curative intervention. In this review, we will present the current state of treatment for the most common pediatric neuromuscular conditions, and detail the treatment strategies with the greatest potential for helping with these devastating diseases.
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Affiliation(s)
- James J. Dowling
- Division of NeurologyHospital for Sick ChildrenTorontoOntarioCanada
- Program for Genetics and Genome BiologyHospital for Sick ChildrenTorontoOntarioCanada
- Departments of Paediatrics and Molecular GeneticsUniversity of TorontoTorontoOntarioCanada
| | | | - Ronald D. Cohn
- Program for Genetics and Genome BiologyHospital for Sick ChildrenTorontoOntarioCanada
- Departments of Paediatrics and Molecular GeneticsUniversity of TorontoTorontoOntarioCanada
| | - Craig Campbell
- Department of PediatricsClinical Neurological SciencesEpidemiologyWestern UniversityLondonOntarioCanada
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19
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Abstract
PURPOSE OF REVIEW Spinal muscular atrophy (SMA) is an inherited childhood neurodegenerative disorder caused by ubiquitous deficiency of the survival motor neuron (SMN) protein - the hallmarks of which are the selective loss of motor neurons and skeletal muscle atrophy. Here, we highlight recent progress in the understanding of SMA pathology and in the development of therapeutic approaches for its treatment. RECENT FINDINGS Phenotypic characterization of mouse models of the disease, combined with analysis of SMN restoration or depletion in a spatially and temporally controlled manner, has yielded key insights into the normal requirement of SMN and SMA pathophysiology. Increasing evidence indicates a higher demand for SMN during neuromuscular development and extends the pathogenic effects of SMN deficiency beyond motor neurons to include additional cells both within and outside the nervous system. These findings have been paralleled by preclinical development of powerful approaches for increasing SMN expression through gene therapy or splicing modulation that are now in human trials. SUMMARY Along with the availability of SMN-upregulating drugs, identification of the specific cell types in which SMN deficiency induces the disease and delineation of the window of opportunity for effective treatment are key advances in the ongoing path to SMA therapy.
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20
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Huang D, Fletcher S, Wilton SD, Palmer N, McLenachan S, Mackey DA, Chen FK. Inherited Retinal Disease Therapies Targeting Precursor Messenger Ribonucleic Acid. Vision (Basel) 2017; 1:vision1030022. [PMID: 31740647 PMCID: PMC6836112 DOI: 10.3390/vision1030022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 07/24/2017] [Accepted: 08/24/2017] [Indexed: 02/07/2023] Open
Abstract
Inherited retinal diseases are an extremely diverse group of genetically and phenotypically heterogeneous conditions characterized by variable maturation of retinal development, impairment of photoreceptor cell function and gradual loss of photoreceptor cells and vision. Significant progress has been made over the last two decades in identifying the many genes implicated in inherited retinal diseases and developing novel therapies to address the underlying genetic defects. Approximately one-quarter of exonic mutations related to human inherited diseases are likely to induce aberrant splicing products, providing opportunities for the development of novel therapeutics that target splicing processes. The feasibility of antisense oligomer mediated splice intervention to treat inherited diseases has been demonstrated in vitro, in vivo and in clinical trials. In this review, we will discuss therapeutic approaches to treat inherited retinal disease, including strategies to correct splicing and modify exon selection at the level of pre-mRNA. The challenges of clinical translation of this class of emerging therapeutics will also be discussed.
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Affiliation(s)
- Di Huang
- Molecular Therapy Laboratory, Murdoch University, Murdoch 6150, Australia
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Sue Fletcher
- Molecular Therapy Laboratory, Murdoch University, Murdoch 6150, Australia
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Steve D. Wilton
- Molecular Therapy Laboratory, Murdoch University, Murdoch 6150, Australia
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Norman Palmer
- Perron Institute, 4th Floor A Block, Queen Elizabeth II Medical Centre, Verdun Street, Nedlands 6009, Australia
| | - Samuel McLenachan
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
| | - David A. Mackey
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
| | - Fred K. Chen
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Nedlands 6009, Australia
- Department of Ophthalmology, Royal Perth Hospital, Perth 6000, Australia
- Correspondence: ; Tel.: +61-8-9381-0817
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21
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Pinard E, Green L, Reutlinger M, Weetall M, Naryshkin NA, Baird J, Chen KS, Paushkin SV, Metzger F, Ratni H. Discovery of a Novel Class of Survival Motor Neuron 2 Splicing Modifiers for the Treatment of Spinal Muscular Atrophy. J Med Chem 2017; 60:4444-4457. [DOI: 10.1021/acs.jmedchem.7b00406] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Emmanuel Pinard
- F. Hoffmann-La Roche Ltd., pRED, Pharma Research & Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Luke Green
- F. Hoffmann-La Roche Ltd., pRED, Pharma Research & Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Michael Reutlinger
- F. Hoffmann-La Roche Ltd., pRED, Pharma Research & Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Marla Weetall
- PTC Therapeutics, Inc., 100
Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Nikolai A. Naryshkin
- PTC Therapeutics, Inc., 100
Corporate Court, South Plainfield, New Jersey 07080, United States
| | - John Baird
- PTC Therapeutics, Inc., 100
Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Karen S. Chen
- SMA Foundation, 888 Seventh
Avenue, Suite 400, New York, New York 10019, United States
| | - Sergey V. Paushkin
- SMA Foundation, 888 Seventh
Avenue, Suite 400, New York, New York 10019, United States
| | - Friedrich Metzger
- F. Hoffmann-La Roche Ltd., pRED, Pharma Research & Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
| | - Hasane Ratni
- F. Hoffmann-La Roche Ltd., pRED, Pharma Research & Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, 4070 Basel, Switzerland
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22
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Fletcher S, Bellgard MI, Price L, Akkari AP, Wilton SD. Translational development of splice-modifying antisense oligomers. Expert Opin Biol Ther 2016; 17:15-30. [PMID: 27805416 DOI: 10.1080/14712598.2017.1250880] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Antisense nucleic acid analogues can interact with pre-mRNA motifs and influence exon or splice site selection and thereby alter gene expression. Design of antisense molecules to target specific motifs can result in either exon exclusion or exon inclusion during splicing. Novel drugs exploiting the antisense concept are targeting rare, life-limiting diseases; however, the potential exists to treat a wide range of conditions by antisense-mediated splice intervention. Areas covered: In this review, the authors discuss the clinical translation of novel molecular therapeutics to address the fatal neuromuscular disorders Duchenne muscular dystrophy and spinal muscular atrophy. The review also highlights difficulties posed by issues pertaining to restricted participant numbers, variable phenotype and disease progression, and the identification and validation of study endpoints. Expert opinion: Translation of novel therapeutics for Duchenne muscular dystrophy and spinal muscular atrophy has been greatly advanced by multidisciplinary research, academic-industry partnerships and in particular, the engagement and support of the patient community. Sponsors, supporters and regulators are cooperating to deliver new drugs and identify and define meaningful outcome measures. Non-conventional and adaptive trial design could be particularly suited to clinical evaluation of novel therapeutics and strategies to treat serious, rare diseases that may be problematic to study using more conventional clinical trial structures.
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Affiliation(s)
- S Fletcher
- a Centre for Neuromuscular and Neurological Disorders , University of Western Australia , Nedlands , Western Australia , Australia.,b Western Australian Neuroscience Research Institute , Nedlands , Western Australia , Australia.,c Centre for Comparative Genomics , Murdoch University , Western Australia , Australia
| | - M I Bellgard
- b Western Australian Neuroscience Research Institute , Nedlands , Western Australia , Australia.,c Centre for Comparative Genomics , Murdoch University , Western Australia , Australia
| | - L Price
- a Centre for Neuromuscular and Neurological Disorders , University of Western Australia , Nedlands , Western Australia , Australia.,b Western Australian Neuroscience Research Institute , Nedlands , Western Australia , Australia.,c Centre for Comparative Genomics , Murdoch University , Western Australia , Australia
| | - A P Akkari
- b Western Australian Neuroscience Research Institute , Nedlands , Western Australia , Australia.,c Centre for Comparative Genomics , Murdoch University , Western Australia , Australia.,d Shiraz Pharmaceuticals, Inc , Chapel Hill , NC , USA
| | - S D Wilton
- a Centre for Neuromuscular and Neurological Disorders , University of Western Australia , Nedlands , Western Australia , Australia.,b Western Australian Neuroscience Research Institute , Nedlands , Western Australia , Australia.,c Centre for Comparative Genomics , Murdoch University , Western Australia , Australia
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23
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Doktor TK, Hua Y, Andersen HS, Brøner S, Liu YH, Wieckowska A, Dembic M, Bruun GH, Krainer AR, Andresen BS. RNA-sequencing of a mouse-model of spinal muscular atrophy reveals tissue-wide changes in splicing of U12-dependent introns. Nucleic Acids Res 2016; 45:395-416. [PMID: 27557711 PMCID: PMC5224493 DOI: 10.1093/nar/gkw731] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 11/21/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is a neuromuscular disorder caused by insufficient levels of the Survival of Motor Neuron (SMN) protein. SMN is expressed ubiquitously and functions in RNA processing pathways that include trafficking of mRNA and assembly of snRNP complexes. Importantly, SMA severity is correlated with decreased snRNP assembly activity. In particular, the minor spliceosomal snRNPs are affected, and some U12-dependent introns have been reported to be aberrantly spliced in patient cells and animal models. SMA is characterized by loss of motor neurons, but the underlying mechanism is largely unknown. It is likely that aberrant splicing of genes expressed in motor neurons is involved in SMA pathogenesis, but increasing evidence indicates that pathologies also exist in other tissues. We present here a comprehensive RNA-seq study that covers multiple tissues in an SMA mouse model. We show elevated U12-intron retention in all examined tissues from SMA mice, and that U12-dependent intron retention is induced upon siRNA knock-down of SMN in HeLa cells. Furthermore, we show that retention of U12-dependent introns is mitigated by ASO treatment of SMA mice and that many transcriptional changes are reversed. Finally, we report on missplicing of several Ca2+ channel genes that may explain disrupted Ca2+ homeostasis in SMA and activation of Cdk5.
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Affiliation(s)
- Thomas Koed Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.,The Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense, Denmark
| | - Yimin Hua
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Henriette Skovgaard Andersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.,The Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense, Denmark
| | - Sabrina Brøner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.,The Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense, Denmark
| | - Ying Hsiu Liu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Anna Wieckowska
- Department of Gamete and Embryo Biology, Division of Reproductive Biology, Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, 10-243 Olsztyn, Poland
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.,The Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense, Denmark
| | - Gitte Hoffmann Bruun
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.,The Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense, Denmark
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Brage Storstein Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark .,The Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense, Denmark
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Somatic Therapy of a Mouse SMA Model with a U7 snRNA Gene Correcting SMN2 Splicing. Mol Ther 2016; 24:1797-1805. [PMID: 27456062 PMCID: PMC5112044 DOI: 10.1038/mt.2016.152] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/18/2016] [Indexed: 12/12/2022] Open
Abstract
Spinal Muscular Atrophy is due to the loss of SMN1 gene function. The duplicate gene SMN2 produces some, but not enough, SMN protein because most transcripts lack exon 7. Thus, promoting the inclusion of this exon is a therapeutic option. We show that a somatic gene therapy using the gene for a modified U7 RNA which stimulates this splicing has a profound and persistent therapeutic effect on the phenotype of a severe Spinal Muscular Atrophy mouse model. To this end, the U7 gene and vector and the production of pure, highly concentrated self-complementary (sc) adenovirus-associated virus 9 vector particles were optimized. Introduction of the functional vector into motoneurons of newborn Spinal Muscular Atrophy mice by intracerebroventricular injection led to a highly significant, dose-dependent increase in life span and improvement of muscle functions. Besides the central nervous system, the therapeutic U7 RNA was expressed in the heart and liver which may additionally have contributed to the observed therapeutic efficacy. This approach provides an additional therapeutic option for Spinal Muscular Atrophy and could also be adapted to treat other diseases of the central nervous system with regulatory small RNA genes.
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Woll MG, Qi H, Turpoff A, Zhang N, Zhang X, Chen G, Li C, Huang S, Yang T, Moon YC, Lee CS, Choi S, Almstead NG, Naryshkin NA, Dakka A, Narasimhan J, Gabbeta V, Welch E, Zhao X, Risher N, Sheedy J, Weetall M, Karp GM. Discovery and Optimization of Small Molecule Splicing Modifiers of Survival Motor Neuron 2 as a Treatment for Spinal Muscular Atrophy. J Med Chem 2016; 59:6070-85. [DOI: 10.1021/acs.jmedchem.6b00460] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Matthew G. Woll
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Hongyan Qi
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Anthony Turpoff
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Nanjing Zhang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Xiaoyan Zhang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Guangming Chen
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Chunshi Li
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Song Huang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Tianle Yang
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Young-Choon Moon
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Chang-Sun Lee
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Soongyu Choi
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Neil G. Almstead
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Nikolai A. Naryshkin
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Amal Dakka
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Jana Narasimhan
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Vijayalakshmi Gabbeta
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Ellen Welch
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Xin Zhao
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Nicole Risher
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Josephine Sheedy
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Marla Weetall
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
| | - Gary M. Karp
- PTC Therapeutics, Inc., 100 Corporate Court, South Plainfield, New Jersey 07080, United States
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