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Gidaro T, Servais L. Nusinersen treatment of spinal muscular atrophy: current knowledge and existing gaps. Dev Med Child Neurol 2019; 61:19-24. [PMID: 30221755 DOI: 10.1111/dmcn.14027] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/25/2018] [Indexed: 01/08/2023]
Abstract
Spinal muscular atrophy (SMA) is a recessive disorder caused by a mutation in the survival motor neuron 1 gene (SMN1); it affects 1 in 11 000 newborn infants. The most severe and most common form, type 1 SMA, is associated with early mortality in most cases and severe disability in survivors. Nusinersen, an antisense oligonucleotide, promotes production of full-length protein from the pseudogene SMN2. Nusinersen treatment prolongs survival of patients with type 1 SMA and allows motor milestone acquisition. Patients with type 2 SMA also show progress on different motor scales after nusinersen treatment. Nusinersen was recently approved by the European Medicines Agency and the US Food and Drug Administration; it is now reimbursed in several European countries and in the USA. In Australia, the transition from expanded access programme to commercial availability is coming soon. In New Zealand, an expanded access programme is opened, and in Canada price negotiation for the treatment is in progress. In this review we exemplify the clinical benefit of nusinersen in subgroups of patients with SMA. Nusinersen represents the first efficacious marked approved drug in type 1 and type 2 SMA. Different knowledge gaps, such as results in older patients, in patients with permanent ventilation, in patients with neonatal forms, or in patients after spinal fusion, still need to be addressed. WHAT THIS PAPER ADDS: Identifies gaps in knowledge about the efficacy of nusinersen in broader populations of patients with spinal muscular atrophy. Identifies open questions in populations of patients where proof of efficacy is available.
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Affiliation(s)
- Teresa Gidaro
- I-Motion - Pediatric Clinical Trials Department, Trousseau Hospital, Paris, France.,Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
| | - Laurent Servais
- I-Motion - Pediatric Clinical Trials Department, Trousseau Hospital, Paris, France.,Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France.,CHU de Liège, Centre de référence des maladies Neuromusculaires, Liège, Belgium
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Iyer CC, Corlett KM, Massoni-Laporte A, Duque SI, Madabusi N, Tisdale S, McGovern VL, Le TT, Zaworski PG, Arnold WD, Pellizzoni L, Burghes AHM. Mild SMN missense alleles are only functional in the presence of SMN2 in mammals. Hum Mol Genet 2018; 27:3404-3416. [PMID: 29982416 PMCID: PMC6140769 DOI: 10.1093/hmg/ddy251] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/19/2018] [Accepted: 07/02/2018] [Indexed: 12/17/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by reduced levels of full-length SMN (FL-SMN). In SMA patients with one or two copies of the Survival Motor Neuron 2 (SMN2) gene there are a number of SMN missense mutations that result in milder-than-predicted SMA phenotypes. These mild SMN missense mutation alleles are often assumed to have partial function. However, it is important to consider the contribution of FL-SMN as these missense alleles never occur in the absence of SMN2. We propose that these patients contain a partially functional oligomeric SMN complex consisting of FL-SMN from SMN2 and mutant SMN protein produced from the missense allele. Here we show that mild SMN missense mutations SMND44V, SMNT74I or SMNQ282A alone do not rescue mice lacking wild-type FL-SMN. Thus, missense mutations are not functional in the absence of FL-SMN. In contrast, when the same mild SMN missense mutations are expressed in a mouse containing two SMN2 copies, functional SMN complexes are formed with the small amount of wild-type FL-SMN produced by SMN2 and the SMA phenotype is completely rescued. This contrasts with SMN missense alleles when studied in C. elegans, Drosophila and zebrafish. Here we demonstrate that the heteromeric SMN complex formed with FL-SMN is functional and sufficient to rescue small nuclear ribonucleoprotein assembly, motor neuron function and rescue the SMA mice. We conclude that mild SMN missense alleles are not partially functional but rather they are completely non-functional in the absence of wild-type SMN in mammals.
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Affiliation(s)
- Chitra C Iyer
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Kaitlyn M Corlett
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Aurélie Massoni-Laporte
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sandra I Duque
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Narasimhan Madabusi
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sarah Tisdale
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Vicki L McGovern
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Thanh T Le
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | | | - W David Arnold
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Arthur H M Burghes
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
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Scoto M, Finkel R, Mercuri E, Muntoni F. Genetic therapies for inherited neuromuscular disorders. THE LANCET CHILD & ADOLESCENT HEALTH 2018; 2:600-609. [PMID: 30119719 DOI: 10.1016/s2352-4642(18)30140-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/23/2018] [Accepted: 04/24/2018] [Indexed: 01/15/2023]
Abstract
Inherited neuromuscular disorders encompass a broad group of genetic conditions, and the discovery of these underlying genes has expanded greatly in the past three decades. The discovery of such genes has enabled more precise diagnosis of these disorders and the development of specific therapeutic approaches that target the genetic basis and pathophysiological pathways. Such translational research has led to the approval of two genetic therapies by the US Food and Drug Administration: eteplirsen for Duchenne muscular dystrophy and nusinersen for spinal muscular atrophy, which are both antisense oligonucleotides that modify pre-mRNA splicing. In this Review we aim to discuss new genetic therapies and ongoing clinical trials for Duchenne muscular dystrophy, spinal muscular atrophy, and other less common childhood neuromuscular disorders.
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Affiliation(s)
- Mariacristina Scoto
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Richard Finkel
- Division of Pediatric Neurology, Nemours Children's Hospital, University of Central Florida College of Medicine, Orlando, FL, USA
| | - Eugenio Mercuri
- Pediatric Neurology and Centro Nemo, IRCSS Fondazione Policlinico Gemelli, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, London, UK; National Institute for Health Research Great Ormond Street Hospital Biomedical Research Centre, London, UK.
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54
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Maruyama R, Touznik A, Yokota T. Evaluation of Exon Inclusion Induced by Splice Switching Antisense Oligonucleotides in SMA Patient Fibroblasts. J Vis Exp 2018. [PMID: 29806836 DOI: 10.3791/57530] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Spinal muscular atrophy (SMA), a lethal neurological disease caused by the loss of SMN1, presents a unique case in the field of antisense oligonucleotide (AON)-mediated therapy. While SMN1 mutations are responsible for the disease, AONs targeting intronic splice silencer (ISS) sites in SMN2, including FDA-approved nusinersen, have been shown to restore SMN expression and ameliorate the symptoms. Currently, many studies involving AON therapy for SMA focus on investigating novel AON chemistries targeting SMN2 that may be more effective and less toxic than nusinersen. Here, we describe a protocol for in vitro evaluation of exon inclusion using lipotransfection of AONs followed by reverse transcription polymerase chain reaction (RT-PCR), quantitative polymerase chain reaction (qPCR), and Western blotting. This method can be employed for various types of AON chemistries. Using this method, we demonstrate that AONs composed of alternating locked nucleic acids (LNAs) and DNA nucleotides (LNA/DNA mixmers) lead to efficient SMN2 exon inclusion and restoration of SMN protein at a very low concentration, and therefore, LNA/DNA mixmer-based antisense oligonucleotides may be an attractive therapeutic strategy to treat splicing defects caused by genetic diseases. The in vitro evaluation method described here is fast, easy, and sensitive enough for the testing of various novel AONs.
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Affiliation(s)
- Rika Maruyama
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry;
| | - Aleksander Touznik
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry
| | - Toshifumi Yokota
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry; Muscular Dystrophy Canada Research Chair, Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry;
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Wood MJA, Talbot K, Bowerman M. Spinal muscular atrophy: antisense oligonucleotide therapy opens the door to an integrated therapeutic landscape. Hum Mol Genet 2018; 26:R151-R159. [PMID: 28977438 DOI: 10.1093/hmg/ddx215] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 06/02/2017] [Indexed: 01/03/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder characterized by loss of spinal cord motor neurons, muscle atrophy and infantile death or severe disability. It is caused by severe reduction of the ubiquitously expressed survival motor neuron (SMN) protein, owing to loss of the SMN1 gene. This would be completely incompatible with survival without the presence of a quasi-identical duplicated gene, SMN2, specific to humans. SMN2 harbours a silent point mutation that favours the production of transcripts lacking exon 7 and a rapidly degraded non-functional SMNΔ7 protein, but from which functional full length SMN protein is produced at very low levels (∼10%). Since the seminal discovery of the SMA-causing gene in 1995, research has focused on the development of various SMN replacement strategies culminating, in December 2016, in the approval of the first precise molecularly targeted therapy for SMA (nusinersen), and a pivotal proof of principle that therapeutic antisense oligonucleotide (ASO) treatment can effectively target the central nervous system (CNS) to treat neurological and neuromuscular disease. Nusinersen is a steric block ASO that binds the SMN2 messenger RNA and promotes exon 7 inclusion and thus increases full length SMN expression. Here, we consider the implications of this therapeutic landmark for SMA therapeutics and discuss how future developments will need to address the challenges of delivering ASO therapies to the CNS, with appropriate efficiency and activity, and how SMN-based therapy should be used in combination with complementary strategies to provide an integrated approach to treat CNS and peripheral pathologies in SMA.
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Affiliation(s)
- Matthew J A Wood
- Department of Physiology, Anatomy and Genetics, University of Oxford OX1 3QX, Oxford, UK
| | - Kevin Talbot
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Melissa Bowerman
- Department of Physiology, Anatomy and Genetics, University of Oxford OX1 3QX, Oxford, UK
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Parente V, Corti S. Advances in spinal muscular atrophy therapeutics. Ther Adv Neurol Disord 2018; 11:1756285618754501. [PMID: 29434670 PMCID: PMC5802612 DOI: 10.1177/1756285618754501] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 10/24/2017] [Indexed: 11/17/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a progressive, recessively inherited neuromuscular disease, characterized by the degeneration of lower motor neurons in the spinal cord and brainstem, which leads to weakness and muscle atrophy. SMA currently represents the most common genetic cause of infant death. SMA is caused by the lack of survival motor neuron (SMN) protein due to mutations, which are often deletions, in the SMN1 gene. In the absence of treatments able to modify the disease course, a considerable burden falls on patients and their families. Greater knowledge of the molecular basis of SMA pathogenesis has fuelled the development of potential therapeutic approaches, which are illustrated here. Nusinersen, a modified antisense oligonucleotide that modulates the splicing of the SMN2 mRNA transcript, is the first approved drug for all types of SMA. Moreover, the first gene therapy clinical trial using adeno-associated virus (AAV) vectors encoding SMN reported positive results in survival and motor milestones achievement. In addition, other strategies are in the pipeline, including modulation of SMN2 transcripts, neuroprotection, and targeting an increasing number of other peripheral targets, including the skeletal muscle. Based on this premise, it is reasonable to expect that therapeutic approaches aimed at treating SMA will soon be changed, and improved, in a meaningful way. We discuss the challenges with regard to the development of novel treatments for patients with SMA, and depict the current and future scenarios as the field enters into a new era of promising effective treatments.
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Affiliation(s)
- Valeria Parente
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefania Corti
- Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122 Milan, Italy
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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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58
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Investigation of New Morpholino Oligomers to Increase Survival Motor Neuron Protein Levels in Spinal Muscular Atrophy. Int J Mol Sci 2018; 19:ijms19010167. [PMID: 29316633 PMCID: PMC5796116 DOI: 10.3390/ijms19010167] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/22/2017] [Accepted: 01/02/2018] [Indexed: 11/23/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal-recessive childhood motor neuron disease and the main genetic cause of infant mortality. SMA is caused by deletions or mutations in the survival motor neuron 1 (SMN1) gene, which results in SMN protein deficiency. Only one approved drug has recently become available and allows for the correction of aberrant splicing of the paralogous SMN2 gene by antisense oligonucleotides (ASOs), leading to production of full-length SMN protein. We have already demonstrated that a sequence of an ASO variant, Morpholino (MO), is particularly suitable because of its safety and efficacy profile and is both able to increase SMN levels and rescue the murine SMA phenotype. Here, we optimized this strategy by testing the efficacy of four new MO sequences targeting SMN2. Two out of the four new MO sequences showed better efficacy in terms of SMN protein production both in SMA induced pluripotent stem cells (iPSCs) and SMAΔ7 mice. Further, the effect was enhanced when different MO sequences were administered in combination. Our data provide an important insight for MO-based treatment for SMA. Optimization of the target sequence and validation of a treatment based on a combination of different MO sequences could support further pre-clinical studies and the progression toward future clinical trials.
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59
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Goyal N, Narayanaswami P. Making sense of antisense oligonucleotides: A narrative review. Muscle Nerve 2017; 57:356-370. [PMID: 29105153 DOI: 10.1002/mus.26001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 12/14/2022]
Abstract
Synthetic nucleic acid sequences that bind to ribonucleic acid (RNA) through Watson-Crick base pairing are known as antisense oligonucleotides (ASOs) because they are complementary to "sense strand" nucleic acids. ASOs bind to selected sequences of RNA and regulate the expression of genes by several mechanisms depending on their chemical properties and targets. They can be used to restore deficient protein expression, reduce the expression of a toxic protein, modify functional effects of proteins, or reduce toxicity of mutant proteins. Two ASOs were approved by the U.S. Food and Drug Administration in 2016: eteplirsen for Duchenne muscular dystrophy and nusinersen for spinal muscular atrophy. Clinical trials in amyotrophic lateral sclerosis and familial amyloid polyneuropathy are ongoing. We review the chemistry, pharmacology, and mechanisms of action of ASOs, preclinical data, and clinical trials in neuromuscular diseases and discuss some ethical, regulatory, and policy considerations in the clinical development and use of ASOs. Muscle Nerve 57: 356-370, 2018.
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Affiliation(s)
- Neelam Goyal
- Neurology/Neuromuscular Disease, Stanford University Hospital, 213 Quarry Road MC 5979, Palo Alto, Ca 94303
| | - Pushpa Narayanaswami
- Neurology/Neuromuscular Disease, Neurology TCC-8, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, Massachusetts, 02215
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60
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Tosolini AP, Sleigh JN. Motor Neuron Gene Therapy: Lessons from Spinal Muscular Atrophy for Amyotrophic Lateral Sclerosis. Front Mol Neurosci 2017; 10:405. [PMID: 29270111 PMCID: PMC5725447 DOI: 10.3389/fnmol.2017.00405] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/21/2017] [Indexed: 12/11/2022] Open
Abstract
Spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS) are severe nervous system diseases characterized by the degeneration of lower motor neurons. They share a number of additional pathological, cellular, and genetic parallels suggesting that mechanistic and clinical insights into one disorder may have value for the other. While there are currently no clinical ALS gene therapies, the splice-switching antisense oligonucleotide, nusinersen, was recently approved for SMA. This milestone was achieved through extensive pre-clinical research and patient trials, which together have spawned fundamental insights into motor neuron gene therapy. We have thus tried to distil key information garnered from SMA research, in the hope that it may stimulate a more directed approach to ALS gene therapy. Not only must the type of therapeutic (e.g., antisense oligonucleotide vs. viral vector) be sensibly selected, but considerable thought must be applied to the where, which, what, and when in order to enhance treatment benefit: to where (cell types and tissues) must the drug be delivered and how can this be best achieved? Which perturbed pathways must be corrected and can they be concurrently targeted? What dosing regime and concentration should be used? When should medication be administered? These questions are intuitive, but central to identifying and optimizing a successful gene therapy. Providing definitive solutions to these quandaries will be difficult, but clear thinking about therapeutic testing is necessary if we are to have the best chance of developing viable ALS gene therapies and improving upon early generation SMA treatments.
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Affiliation(s)
- Andrew P Tosolini
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
| | - James N Sleigh
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
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61
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Rinaldi C, Wood MJA. Antisense oligonucleotides: the next frontier for treatment of neurological disorders. Nat Rev Neurol 2017; 14:9-21. [PMID: 29192260 DOI: 10.1038/nrneurol.2017.148] [Citation(s) in RCA: 463] [Impact Index Per Article: 66.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Antisense oligonucleotides (ASOs) were first discovered to influence RNA processing and modulate protein expression over two decades ago; however, progress translating these agents into the clinic has been hampered by inadequate target engagement, insufficient biological activity, and off-target toxic effects. Over the years, novel chemical modifications of ASOs have been employed to address these issues. These modifications, in combination with elucidation of the mechanism of action of ASOs and improved clinical trial design, have provided momentum for the translation of ASO-based strategies into therapies. Many neurological conditions lack an effective treatment; however, as research progressively disentangles the pathogenic mechanisms of these diseases, they provide an ideal platform to test ASO-based strategies. This steady progress reached a pinnacle in the past few years with approvals of ASOs for the treatment of spinal muscular atrophy and Duchenne muscular dystrophy, which represent landmarks in a field in which disease-modifying therapies were virtually non-existent. With the rapid development of improved next-generation ASOs toward clinical application, this technology now holds the potential to have a dramatic effect on the treatment of many neurological conditions in the near future.
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Affiliation(s)
- Carlo Rinaldi
- Department of Physiology, Anatomy and Genetics, University of Oxford, Le Gros Clark Building, South Parks Road, Oxford OX1 3QX, UK
| | - Matthew J A Wood
- Department of Physiology, Anatomy and Genetics, University of Oxford, Le Gros Clark Building, South Parks Road, Oxford OX1 3QX, UK
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62
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Rodriguez-Muela N, Litterman NK, Norabuena EM, Mull JL, Galazo MJ, Sun C, Ng SY, Makhortova NR, White A, Lynes MM, Chung WK, Davidow LS, Macklis JD, Rubin LL. Single-Cell Analysis of SMN Reveals Its Broader Role in Neuromuscular Disease. Cell Rep 2017; 18:1484-1498. [PMID: 28178525 DOI: 10.1016/j.celrep.2017.01.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 11/09/2016] [Accepted: 01/15/2017] [Indexed: 12/29/2022] Open
Abstract
The mechanism underlying selective motor neuron (MN) death remains an essential question in the MN disease field. The MN disease spinal muscular atrophy (SMA) is attributable to reduced levels of the ubiquitous protein SMN. Here, we report that SMN levels are widely variable in MNs within a single genetic background and that this heterogeneity is seen not only in SMA MNs but also in MNs derived from controls and amyotrophic lateral sclerosis (ALS) patients. Furthermore, cells with low SMN are more susceptible to cell death. These findings raise the important clinical implication that some SMN-elevating therapeutics might be effective in MN diseases besides SMA. Supporting this, we found that increasing SMN across all MN populations using an Nedd8-activating enzyme inhibitor promotes survival in both SMA and ALS-derived MNs. Altogether, our work demonstrates that examination of human neurons at the single-cell level can reveal alternative strategies to be explored in the treatment of degenerative diseases.
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Affiliation(s)
- Natalia Rodriguez-Muela
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
| | - Nadia K Litterman
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Erika M Norabuena
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Jesse L Mull
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Maria José Galazo
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Chicheng Sun
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Shi-Yan Ng
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Nina R Makhortova
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Andrew White
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
| | - Maureen M Lynes
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Wendy K Chung
- Department of Pediatrics, Columbia University, New York, NY 10032, USA
| | - Lance S Davidow
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Jeffrey D Macklis
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
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63
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Nelson CE, Robinson-Hamm JN, Gersbach CA. Genome engineering: a new approach to gene therapy for neuromuscular disorders. Nat Rev Neurol 2017; 13:647-661. [DOI: 10.1038/nrneurol.2017.126] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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64
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Schoch KM, Miller TM. Antisense Oligonucleotides: Translation from Mouse Models to Human Neurodegenerative Diseases. Neuron 2017. [PMID: 28641106 DOI: 10.1016/j.neuron.2017.04.010] [Citation(s) in RCA: 196] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Multiple neurodegenerative diseases are characterized by single-protein dysfunction and aggregation. Treatment strategies for these diseases have often targeted downstream pathways to ameliorate consequences of protein dysfunction; however, targeting the source of that dysfunction, the affected protein itself, seems most judicious to achieve a highly effective therapeutic outcome. Antisense oligonucleotides (ASOs) are small sequences of DNA able to target RNA transcripts, resulting in reduced or modified protein expression. ASOs are ideal candidates for the treatment of neurodegenerative diseases, given numerous advancements made to their chemical modifications and delivery methods. Successes achieved in both animal models and human clinical trials have proven ASOs both safe and effective. With proper considerations in mind regarding the human applicability of ASOs, we anticipate ongoing in vivo research and clinical trial development of ASOs for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Kathleen M Schoch
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Timothy M Miller
- Department of Neurology, Hope Center for Neurological Disorders, Washington University in St. Louis, St. Louis, MO 63110, USA.
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65
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Zhang QJ, Lin X, Li JJ, Lu YQ, Guo XX, Dong EL, Zhao M, He J, Wang N, Chen WJ. Application of urine cells in drug intervention for spinal muscular atrophy. Exp Ther Med 2017; 14:1993-1998. [PMID: 28962115 PMCID: PMC5609093 DOI: 10.3892/etm.2017.4791] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 05/05/2017] [Indexed: 01/07/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a lethal childhood neurodegenerative disorder that is caused by the homozygous deletion of survival motor neuron 1 (SMN1). To date, no effective treatments are available. In the current study, urine cells taken from SMA patients were cultured and the application of patient-derived urine cells was determined in drug intervention. A total of 13 SMA patient-derived urine cell lines and 40 control cell lines were established. SMN was highly expressed in the nucleus and cytoplasm. Patient-derived urine cells expressed low levels of SMN protein compared with controls, they exhibited good tolerance to chemical and electrical damage. SMN expression was upregulated following treatment with histone deacetylase inhibitors and the effect was greater in groups treated with morpholino modified antisense oligo, which targets ISS-N1 in SMN2 intron 7. The results of the current study indicated that SMA patient-derived urine cells may be useful in the initial screening of potential compounds and drugs to treat SMA.
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Affiliation(s)
- Qi-Jie Zhang
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Xiang Lin
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Jin-Jing Li
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Ying-Qian Lu
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Xin-Xin Guo
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - En-Lin Dong
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Miao Zhao
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Jin He
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Ning Wang
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China.,Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
| | - Wan-Jin Chen
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China.,Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, Fujian 350005, P.R. China
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66
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Touznik A, Maruyama R, Hosoki K, Echigoya Y, Yokota T. LNA/DNA mixmer-based antisense oligonucleotides correct alternative splicing of the SMN2 gene and restore SMN protein expression in type 1 SMA fibroblasts. Sci Rep 2017. [PMID: 28623256 PMCID: PMC5473822 DOI: 10.1038/s41598-017-03850-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive disorder affecting motor neurons, and is currently the most frequent genetic cause of infant mortality. SMA is caused by a loss-of-function mutation in the survival motor neuron 1 (SMN1) gene. SMN2 is an SMN1 paralogue, but cannot compensate for the loss of SMN1 since exon 7 in SMN2 mRNA is excluded (spliced out) due to a single C-to-T nucleotide transition in the exon 7. One of the most promising strategies to treat SMA is antisense oligonucleotide (AON)-mediated therapy. AONs are utilized to block intronic splicing silencer number 1 (ISS-N1) on intron 7 of SMN2, which causes exon 7 inclusion of the mRNA and the recovery of the expression of functional SMN protein from the endogenous SMN2 gene. We developed novel locked nucleic acid (LNA)-based antisense oligonucleotides (LNA/DNA mixmers), which efficiently induce exon 7 inclusion in SMN2 and restore the SMN protein production in SMA patient fibroblasts. The mixmers are highly specific to the targeted sequence, and showed significantly higher efficacy than an all-LNA oligonucleotide with the equivalent sequence. These data suggest that use of LNA/DNA mixmer-based AONs may be an attractive therapeutic strategy to treat SMA.
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Affiliation(s)
- Aleksander Touznik
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry, Edmonton, Alberta, Canada
| | - Rika Maruyama
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry, Edmonton, Alberta, Canada.
| | - Kana Hosoki
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry, Edmonton, Alberta, Canada
| | - Yusuke Echigoya
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry, Edmonton, Alberta, Canada
| | - Toshifumi Yokota
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry, Edmonton, Alberta, Canada. .,The Friends of Garrett Cumming Research & Muscular Dystrophy Canada HM Toupin Neurological Science Endowed Research Chair, Edmonton, Alberta, Canada.
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67
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Ren X, Deng R, Wang L, Zhang K, Li J. RNA splicing process analysis for identifying antisense oligonucleotide inhibitors with padlock probe-based isothermal amplification. Chem Sci 2017; 8:5692-5698. [PMID: 28989608 PMCID: PMC5621167 DOI: 10.1039/c7sc01336a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 06/07/2017] [Indexed: 12/24/2022] Open
Abstract
We report a highly sensitive method for quantifying the splicing products in different steps, enabling us to analyze the splicing process and identify ASO inhibitors.
RNA splicing, which mainly involves two transesterification steps, is a fundamental process of gene expression and its abnormal regulation contributes to serious genetic diseases. Antisense oligonucleotides (ASOs) are genetic control tools that can be used to specifically control genes through alteration of the RNA splicing pathway. Despite intensive research, how ASOs or various other factors influence the multiple processes of RNA splicing still remains obscure. This is largely due to an inability to analyze the splicing efficiency of each step in the RNA splicing process with high sensitivity. We addressed this limitation by introducing a padlock probe-based isothermal amplification assay to achieve quantification of the specific products in different splicing steps. With this amplified assay, the roles that ASOs play in RNA splicing inhibition in the first and second steps could be distinguished. We identified that 5′-ASO could block RNA splicing by inhibiting the first step, while 3′-ASO could block RNA splicing by inhibiting the second step. This method provides a versatile tool for assisting efficient ASO design and discovering new splicing modulators and therapeutic drugs.
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Affiliation(s)
- Xiaojun Ren
- School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 100081 , China.,Department of Chemistry , Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Ruijie Deng
- Department of Chemistry , Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Lida Wang
- Department of Chemistry , Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Kaixiang Zhang
- Department of Chemistry , Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Jinghong Li
- Department of Chemistry , Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
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68
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Meijboom KE, Wood MJA, McClorey G. Splice-Switching Therapy for Spinal Muscular Atrophy. Genes (Basel) 2017; 8:genes8060161. [PMID: 28604635 PMCID: PMC5485525 DOI: 10.3390/genes8060161] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 05/26/2017] [Accepted: 06/02/2017] [Indexed: 01/17/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a genetic disorder with severity ranging from premature death in infants to restricted motor function in adult life. Despite the genetic cause of this disease being known for over twenty years, only recently has a therapy been approved to treat the most severe form of this disease. Here we discuss the genetic basis of SMA and the subsequent studies that led to the utilization of splice switching oligonucleotides to enhance production of SMN protein, which is absent in patients, through a mechanism of exon inclusion into the mature mRNA. Whilst approval of oligonucleotide-based therapies for SMA should be celebrated, we also discuss some of the limitations of this approach and alternate genetic strategies that are currently underway in clinical trials.
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Affiliation(s)
- Katharina E Meijboom
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
| | - Matthew J A Wood
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
| | - Graham McClorey
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
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69
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Therapeutic approaches for spinal muscular atrophy (SMA). Gene Ther 2017; 24:514-519. [DOI: 10.1038/gt.2017.45] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/09/2017] [Indexed: 12/13/2022]
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70
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Jablonka S, Sendtner M. Developmental regulation of SMN expression: pathophysiological implications and perspectives for therapy development in spinal muscular atrophy. Gene Ther 2017; 24:506-513. [DOI: 10.1038/gt.2017.46] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/16/2017] [Accepted: 05/19/2017] [Indexed: 12/18/2022]
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71
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Singh NN, Howell MD, Androphy EJ, Singh RN. How the discovery of ISS-N1 led to the first medical therapy for spinal muscular atrophy. Gene Ther 2017; 24:520-526. [PMID: 28485722 DOI: 10.1038/gt.2017.34] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 04/14/2017] [Accepted: 04/26/2017] [Indexed: 12/14/2022]
Abstract
Spinal muscular atrophy (SMA), a prominent genetic disease of infant mortality, is caused by low levels of survival motor neuron (SMN) protein owing to deletions or mutations of the SMN1 gene. SMN2, a nearly identical copy of SMN1 present in humans, cannot compensate for the loss of SMN1 because of predominant skipping of exon 7 during pre-mRNA splicing. With the recent US Food and Drug Administration approval of nusinersen (Spinraza), the potential for correction of SMN2 exon 7 splicing as an SMA therapy has been affirmed. Nusinersen is an antisense oligonucleotide that targets intronic splicing silencer N1 (ISS-N1) discovered in 2004 at the University of Massachusetts Medical School. ISS-N1 has emerged as the model target for testing the therapeutic efficacy of antisense oligonucleotides using different chemistries as well as different mouse models of SMA. Here, we provide a historical account of events that led to the discovery of ISS-N1 and describe the impact of independent validations that raised the profile of ISS-N1 as one of the most potent antisense targets for the treatment of a genetic disease. Recent approval of nusinersen provides a much-needed boost for antisense technology that is just beginning to realize its potential. Beyond treating SMA, the ISS-N1 target offers myriad potentials for perfecting various aspects of the nucleic-acid-based technology for the amelioration of the countless number of pathological conditions.
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Affiliation(s)
- N N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - M D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - E J Androphy
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - R N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
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72
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Hoffman EP. Facilitating orphan drug development: Proceedings of the TREAT-NMD International Conference, December 2015, Washington, DC, USA. Neuromuscul Disord 2017; 27:693-701. [PMID: 28434909 DOI: 10.1016/j.nmd.2017.02.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 02/28/2017] [Indexed: 11/24/2022]
Affiliation(s)
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- Binghamton University - SUNY, USA
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- Binghamton University - SUNY, USA
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73
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Gender-Specific Amelioration of SMA Phenotype upon Disruption of a Deep Intronic Structure by an Oligonucleotide. Mol Ther 2017; 25:1328-1341. [PMID: 28412171 DOI: 10.1016/j.ymthe.2017.03.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/18/2017] [Accepted: 03/28/2017] [Indexed: 01/01/2023] Open
Abstract
Spinal muscular atrophy (SMA), the leading genetic disease of children, is caused by low levels of survival motor neuron (SMN) protein. Here, we employ A15/283, an antisense oligonucleotide targeting a deep intronic sequence/structure, to examine the impact of restoration of SMN in a mild SMA mouse model. We show gender-specific amelioration of tail necrosis upon subcutaneous administrations of A15/283 into SMA mice at postnatal days 1 and 3. We also demonstrate that a modest increase in SMN due to early administrations of A15/283 dramatically improves testicular development and spermatogenesis. Our results reveal near total correction of expression of several genes in adult testis upon temporary increase in SMN during early postnatal development. This is the first demonstration of in vivo efficacy of an antisense oligonucleotide targeting a deep intronic sequence/structure. This is also the first report of gender-specific amelioration of SMA pathology upon a modest peripheral increase of SMN.
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74
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Sardone V, Zhou H, Muntoni F, Ferlini A, Falzarano MS. Antisense Oligonucleotide-Based Therapy for Neuromuscular Disease. Molecules 2017; 22:molecules22040563. [PMID: 28379182 PMCID: PMC6154734 DOI: 10.3390/molecules22040563] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/28/2017] [Accepted: 03/14/2017] [Indexed: 02/06/2023] Open
Abstract
Neuromuscular disorders such as Duchenne Muscular Dystrophy and Spinal Muscular Atrophy are neurodegenerative genetic diseases characterized primarily by muscle weakness and wasting. Until recently there were no effective therapies for these conditions, but antisense oligonucleotides, a new class of synthetic single stranded molecules of nucleic acids, have demonstrated promising experimental results and are at different stages of regulatory approval. The antisense oligonucleotides can modulate the protein expression via targeting hnRNAs or mRNAs and inducing interference with splicing, mRNA degradation, or arrest of translation, finally, resulting in rescue or reduction of the target protein expression. Different classes of antisense oligonucleotides are being tested in several clinical trials, and limitations of their clinical efficacy and toxicity have been reported for some of these compounds, while more encouraging results have supported the development of others. New generation antisense oligonucleotides are also being tested in preclinical models together with specific delivery systems that could allow some of the limitations of current antisense oligonucleotides to be overcome, to improve the cell penetration, to achieve more robust target engagement, and hopefully also be associated with acceptable toxicity. This review article describes the chemical properties and molecular mechanisms of action of the antisense oligonucleotides and the therapeutic implications these compounds have in neuromuscular diseases. Current strategies and carrier systems available for the oligonucleotides delivery will be also described to provide an overview on the past, present and future of these appealing molecules.
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Affiliation(s)
- Valentina Sardone
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neuroscience Programme, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK.
| | - Haiyan Zhou
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neuroscience Programme, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK.
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neuroscience Programme, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK.
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London WC1N 3BG, UK.
| | - Alessandra Ferlini
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neuroscience Programme, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK.
- UOL Medical Genetics, University of Ferrara, Ferrara 44121, Italy.
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75
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Robin V, Griffith G, Carter JPL, Leumann CJ, Garcia L, Goyenvalle A. Efficient SMN Rescue following Subcutaneous Tricyclo-DNA Antisense Oligonucleotide Treatment. MOLECULAR THERAPY. NUCLEIC ACIDS 2017. [PMID: 28624227 PMCID: PMC5415958 DOI: 10.1016/j.omtn.2017.02.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Spinal muscular atrophy (SMA) is a recessive disease caused by mutations in the SMN1 gene, which encodes the protein survival motor neuron (SMN), whose absence dramatically affects the survival of motor neurons. In humans, the severity of the disease is lessened by the presence of a gene copy, SMN2. SMN2 differs from SMN1 by a C-to-T transition in exon 7, which modifies pre-mRNA splicing and prevents successful SMN synthesis. Splice-switching approaches using antisense oligonucleotides (AONs) have already been shown to correct this SMN2 gene transition, providing a therapeutic avenue for SMA. However, AON administration to the CNS presents additional hurdles. In this study, we show that systemic delivery of tricyclo-DNA (tcDNA) AONs in a type III SMA mouse augments retention of exon 7 in SMN2 mRNA both in peripheral organs and the CNS. Mild type III SMA mice were selected as opposed to the severe type I model in order to test tcDNA efficacy and their ability to enter the CNS after maturation of the blood brain barrier (BBB). Furthermore, subcutaneous treatment significantly improved the necrosis phenotype and respiratory function. In summary, our data support that tcDNA oligomers effectively cross the blood-brain barrier and offer a promising systemic alternative for treating SMA.
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Affiliation(s)
- Valérie Robin
- Université Versailles Saint Quentin, INSERM U1179, 78180 Montigny-le-Bretonneux, France.
| | - Graziella Griffith
- Université Versailles Saint Quentin, INSERM U1179, 78180 Montigny-le-Bretonneux, France
| | - John-Paul L Carter
- Université Versailles Saint Quentin, INSERM U1179, 78180 Montigny-le-Bretonneux, France
| | - Christian J Leumann
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Luis Garcia
- Université Versailles Saint Quentin, INSERM U1179, 78180 Montigny-le-Bretonneux, France
| | - Aurélie Goyenvalle
- Université Versailles Saint Quentin, INSERM U1179, 78180 Montigny-le-Bretonneux, France.
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76
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Oligonucleotide therapies for disorders of the nervous system. Nat Biotechnol 2017; 35:249-263. [PMID: 28244991 DOI: 10.1038/nbt.3784] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 01/09/2017] [Indexed: 12/14/2022]
Abstract
Oligonucleotide therapies are currently experiencing a resurgence driven by advances in backbone chemistry and discoveries of novel therapeutic pathways that can be uniquely and efficiently modulated by the oligonucleotide drugs. A quarter of a century has passed since oligonucleotides were first applied in living mammalian brain to modulate gene expression. Despite challenges in delivery to the brain, multiple oligonucleotide-based compounds are now being developed for treatment of human brain disorders by direct delivery inside the blood brain barrier (BBB). Notably, the first new central nervous system (CNS)-targeted oligonucleotide-based drug (nusinersen/Spinraza) was approved by US Food and Drug Administration (FDA) in late 2016 and several other compounds are in advanced clinical trials. Human testing of brain-targeted oligonucleotides has highlighted unusual pharmacokinetic and pharmacodynamic properties of these compounds, including complex active uptake mechanisms, low systemic exposure, extremely long half-lives, accumulation and gradual release from subcellular depots. Further work on oligonucleotide uptake, development of formulations for delivery across the BBB and relevant disease biology studies are required for further optimization of the oligonucleotide drug development process for brain applications.
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77
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Tu WY, Simpson JE, Highley JR, Heath PR. Spinal muscular atrophy: Factors that modulate motor neurone vulnerability. Neurobiol Dis 2017; 102:11-20. [PMID: 28161391 DOI: 10.1016/j.nbd.2017.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/10/2017] [Accepted: 01/31/2017] [Indexed: 01/07/2023] Open
Abstract
Spinal muscular atrophy (SMA), a leading genetic cause of infant death, is a neurodegenerative disease characterised by the selective loss of particular groups of motor neurones in the anterior horn of the spinal cord with concomitant muscle weakness. To date, no effective treatment is available, however, there are ongoing clinical trials are in place which promise much for the future. However, there remains an ongoing problem in trying to link a single gene loss to motor neurone degeneration. Fortunately, given successful disease models that have been established and intensive studies on SMN functions in the past ten years, we are fast approaching the stage of identifying the underlying mechanisms of SMA pathogenesis Here we discuss potential disease modifying factors on motor neurone vulnerability, in the belief that these factors give insight into the pathological mechanisms of SMA and therefore possible therapeutic targets.
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Affiliation(s)
- Wen-Yo Tu
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Julie E Simpson
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - J Robin Highley
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Paul R Heath
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK.
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78
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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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79
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Shabanpoor F, Hammond SM, Abendroth F, Hazell G, Wood MJA, Gait MJ. Identification of a Peptide for Systemic Brain Delivery of a Morpholino Oligonucleotide in Mouse Models of Spinal Muscular Atrophy. Nucleic Acid Ther 2017; 27:130-143. [PMID: 28118087 PMCID: PMC5467147 DOI: 10.1089/nat.2016.0652] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Splice-switching antisense oligonucleotides are emerging treatments for neuromuscular diseases, with several splice-switching oligonucleotides (SSOs) currently undergoing clinical trials such as for Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA). However, the development of systemically delivered antisense therapeutics has been hampered by poor tissue penetration and cellular uptake, including crossing of the blood–brain barrier (BBB) to reach targets in the central nervous system (CNS). For SMA application, we have investigated the ability of various BBB-crossing peptides for CNS delivery of a splice-switching phosphorodiamidate morpholino oligonucleotide (PMO) targeting survival motor neuron 2 (SMN2) exon 7 inclusion. We identified a branched derivative of the well-known ApoE (141–150) peptide, which as a PMO conjugate was capable of exon inclusion in the CNS following systemic administration, leading to an increase in the level of full-length SMN2 transcript. Treatment of newborn SMA mice with this peptide-PMO (P-PMO) conjugate resulted in a significant increase in the average lifespan and gains in weight, muscle strength, and righting reflexes. Systemic treatment of adult SMA mice with this newly identified P-PMO also resulted in small but significant increases in the levels of SMN2 pre-messenger RNA (mRNA) exon inclusion in the CNS and peripheral tissues. This work provides proof of principle for the ability to select new peptide paradigms to enhance CNS delivery and activity of a PMO SSO through use of a peptide-based delivery platform for the treatment of SMA potentially extending to other neuromuscular and neurodegenerative diseases.
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Affiliation(s)
- Fazel Shabanpoor
- 1 Medical Research Council, Laboratory of Molecular Biology , Cambridge, United Kingdom
| | - Suzan M Hammond
- 2 Department of Physiology, Anatomy, and Genetics, University of Oxford , Oxford, United Kingdom
| | - Frank Abendroth
- 1 Medical Research Council, Laboratory of Molecular Biology , Cambridge, United Kingdom
| | - Gareth Hazell
- 2 Department of Physiology, Anatomy, and Genetics, University of Oxford , Oxford, United Kingdom
| | - Matthew J A Wood
- 2 Department of Physiology, Anatomy, and Genetics, University of Oxford , Oxford, United Kingdom
| | - Michael J Gait
- 1 Medical Research Council, Laboratory of Molecular Biology , Cambridge, United Kingdom
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80
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Miletta MC, Flück CE, Mullis PE. Targeting GH-1 splicing as a novel pharmacological strategy for growth hormone deficiency type II. Biochem Pharmacol 2017; 124:1-9. [PMID: 27457999 DOI: 10.1016/j.bcp.2016.07.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 07/21/2016] [Indexed: 10/21/2022]
Abstract
Isolated growth hormone deficiency type II (IGHD II) is a rare genetic splicing disorder characterized by reduced growth hormone (GH) secretion and short stature. It is mainly caused by autosomal dominant-negative mutations within the growth hormone gene (GH-1) which results in missplicing at the mRNA level and the subsequent loss of exon 3, producing the 17.5-kDa GH isoform: a mutant and inactive GH protein that reduces the stability and the secretion of the 22-kDa GH isoform, the main biologically active GH form. At present, patients suffering from IGHD II are treated with daily injections of recombinant human GH (rhGH) in order to reach normal height. However, this type of replacement therapy, although effective in terms of growth, does not prevent the toxic effects of the 17.5-kDa mutant on the pituitary gland, which may eventually lead to other hormonal deficiencies. As the severity of the disease inversely correlates with the 17.5-kDa/22-kDa ratio, increasing the inclusion of exon 3 is expected to ameliorate disease symptoms. This review focuses on the recent advances in experimental and therapeutic strategies applicable to treat IGHD II in clinical and preclinical contexts. Several avenues for alternative IGHD II therapy will be discussed including the use of small interfering RNA (siRNA) and short hairpin RNA (shRNA) constructs that specifically target the exon 3-deleted transcripts as well as the application of histone deacetylase inhibitors (HDACi) and antisense oligonucleotides (AONs) to enhance full-length GH-1 transcription, correct GH-1 exon 3 splicing and manipulate GH pathway.
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Affiliation(s)
- Maria Consolata Miletta
- Division of Paediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics and Department of Clinical Research, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Christa E Flück
- Division of Paediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics and Department of Clinical Research, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - Primus-E Mullis
- Division of Paediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics and Department of Clinical Research, Inselspital, Bern University Hospital, University of Bern, Switzerland
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81
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Nizzardo M, Rizzuti M. Intracerebroventricular Delivery in Mice for Motor Neuron Diseases. Methods Mol Biol 2017; 1565:229-239. [PMID: 28364247 DOI: 10.1007/978-1-4939-6817-6_19] [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: 06/07/2023]
Abstract
The use of antisense oligonucleotides to target specific mRNA sequences represents a promising therapeutic strategy for neurological disorders. Recent advances in antisense technology enclose the development of phosphorodiamidate morpholino oligomers (MO), which is one of the best candidates for molecular therapies due to MO's excellent pharmacological profile.Nevertheless, the route of administration of antisense compounds represents a critical issue in the neurological field. Particularly, as regards motor neuron diseases, intracerebroventricular (ICV) injection is undoubtedly the most efficient procedure to directly deliver therapeutic molecules in the central nervous system (CNS). Indeed, we recently demonstrated the outstanding efficacy of the MO antisense approach by its direct administration to CNS of the transgenic mouse models of Spinal Muscular Atrophy (SMA) and Amyotrophic Lateral Sclerosis (ALS).Here, we describe methods to perform the ICV delivery of MO in neonatal SMA mice and in adult ALS mice.
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Affiliation(s)
- M Nizzardo
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, and Neurology Unit, IRCCS Foundation Ca' Granda, Ospedale Maggiore Policlinico, 20122, Milan, Italy.
| | - M Rizzuti
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, and Neurology Unit, IRCCS Foundation Ca' Granda, Ospedale Maggiore Policlinico, 20122, Milan, Italy
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82
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Ottesen EW. ISS-N1 makes the First FDA-approved Drug for Spinal Muscular Atrophy. Transl Neurosci 2017; 8:1-6. [PMID: 28400976 PMCID: PMC5382937 DOI: 10.1515/tnsci-2017-0001] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 01/12/2017] [Indexed: 12/20/2022] Open
Abstract
Spinal muscular atrophy (SMA) is one of the leading genetic diseases of children and infants. SMA is caused by deletions or mutations of Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, cannot compensate for the loss of SMN1 due to predominant skipping of exon 7. While various regulatory elements that modulate SMN2 exon 7 splicing have been proposed, intronic splicing silencer N1 (ISS-N1) has emerged as the most promising target thus far for antisense oligonucleotide-mediated splicing correction in SMA. Upon procuring exclusive license from the University of Massachussets Medical School in 2010, Ionis Pharmaceuticals (formerly ISIS Pharamaceuticals) began clinical development of Spinraza™ (synonyms: Nusinersen, IONIS-SMNRX, ISIS-SMNRX), an antisense drug based on ISS-N1 target. Spinraza™ showed very promising results at all steps of the clinical development and was approved by US Food and Drug Administration (FDA) on December 23, 2016. Spinraza™ is the first FDA-approved treatment for SMA and the first antisense drug to restore expression of a fully functional protein via splicing correction. The success of Spinraza™ underscores the potential of intronic sequences as promising therapeutic targets and sets the stage for further improvement of antisense drugs based on advanced oligonucleotide chemistries and delivery protocols.
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Affiliation(s)
- Eric W. Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
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83
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Bishop KM. Progress and promise of antisense oligonucleotide therapeutics for central nervous system diseases. Neuropharmacology 2016; 120:56-62. [PMID: 27998711 DOI: 10.1016/j.neuropharm.2016.12.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/15/2016] [Accepted: 12/16/2016] [Indexed: 12/14/2022]
Abstract
Antisense oligonucleotide (ASO) drugs are an emerging class of therapeutics that have recently demonstrated progress and promise to treat diseases of the central nervous system (CNS). ASOs for a variety of targets and mechanisms are currently being investigated in clinical trials and pre-clinically for a number of CNS diseases. This review examines the available data regarding central ASO delivery, distribution, pharmacokinetics, pharmacodynamics and therapeutic opportunities. This article is part of the Special Issue entitled "Beyond small molecules for neurological disorders".
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84
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Arnold WD, Duque S, Iyer CC, Zaworski P, McGovern VL, Taylor SJ, von Herrmann KM, Kobayashi DT, Chen KS, Kolb SJ, Paushkin SV, Burghes AHM. Normalization of Patient-Identified Plasma Biomarkers in SMNΔ7 Mice following Postnatal SMN Restoration. PLoS One 2016; 11:e0167077. [PMID: 27907033 PMCID: PMC5132001 DOI: 10.1371/journal.pone.0167077] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 11/08/2016] [Indexed: 12/11/2022] Open
Abstract
INTRODUCTION AND OBJECTIVE Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disorder. SMA is caused by homozygous loss of the SMN1 gene and retention of the SMN2 gene resulting in reduced levels of full length SMN protein that are insufficient for motor neuron function. Various treatments that restore levels of SMN are currently in clinical trials and biomarkers are needed to determine the response to treatment. Here, we sought to investigate in SMA mice a set of plasma analytes, previously identified in patients with SMA to correlate with motor function. The goal was to determine whether levels of plasma markers were altered in the SMNΔ7 mouse model of SMA and whether postnatal SMN restoration resulted in normalization of the biomarkers. METHODS SMNΔ7 and control mice were treated with antisense oligonucleotides (ASO) targeting ISS-N1 to increase SMN protein from SMN2 or scramble ASO (sham treatment) via intracerebroventricular injection on postnatal day 1 (P1). Brain, spinal cord, quadriceps muscle, and liver were analyzed for SMN protein levels at P12 and P90. Ten plasma biomarkers (a subset of biomarkers in the SMA-MAP panel available for analysis in mice) were analyzed in plasma obtained at P12, P30, and P90. RESULTS Of the eight plasma biomarkers assessed, 5 were significantly changed in sham treated SMNΔ7 mice compared to control mice and were normalized in SMNΔ7 mice treated with ASO. CONCLUSION This study defines a subset of the SMA-MAP plasma biomarker panel that is abnormal in the most commonly used mouse model of SMA. Furthermore, some of these markers are responsive to postnatal SMN restoration. These findings support continued clinical development of these potential prognostic and pharmacodynamic biomarkers.
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MESH Headings
- Animals
- Animals, Newborn
- Biomarkers/metabolism
- Brain/metabolism
- Brain/pathology
- Clinical Trials as Topic
- Disease Models, Animal
- Gene Expression Regulation
- Genetic Complementation Test
- Humans
- Injections, Intraventricular
- Liver/metabolism
- Liver/pathology
- Mice
- Mice, Transgenic
- Motor Neurons/metabolism
- Motor Neurons/pathology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscular Atrophy, Spinal/genetics
- Muscular Atrophy, Spinal/metabolism
- Muscular Atrophy, Spinal/pathology
- Oligonucleotides, Antisense/genetics
- Oligonucleotides, Antisense/metabolism
- Spinal Cord/metabolism
- Spinal Cord/pathology
- Survival of Motor Neuron 1 Protein/genetics
- Survival of Motor Neuron 1 Protein/metabolism
- Survival of Motor Neuron 2 Protein/genetics
- Survival of Motor Neuron 2 Protein/metabolism
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Affiliation(s)
- W. David Arnold
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
- Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
| | - Sandra Duque
- VIB Center for the Biology of Disease – KU Leuven Department of Human Genetics, Leuven Belgium, United States of America
| | - Chitra C. Iyer
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
| | | | - Vicki L. McGovern
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
| | | | | | | | - Karen S. Chen
- SMA Foundation, New York, New York, United States of America
| | - Stephen J. Kolb
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
| | | | - Arthur H. M. Burghes
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus Ohio, United States of America
- * E-mail:
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85
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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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86
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Szunyogova E, Zhou H, Maxwell GK, Powis RA, Francesco M, Gillingwater TH, Parson SH. Survival Motor Neuron (SMN) protein is required for normal mouse liver development. Sci Rep 2016; 6:34635. [PMID: 27698380 PMCID: PMC5048144 DOI: 10.1038/srep34635] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 09/12/2016] [Indexed: 01/15/2023] Open
Abstract
Spinal Muscular Atrophy (SMA) is caused by mutation or deletion of the survival motor neuron 1 (SMN1) gene. Decreased levels of, cell-ubiquitous, SMN protein is associated with a range of systemic pathologies reported in severe patients. Despite high levels of SMN protein in normal liver, there is no comprehensive study of liver pathology in SMA. We describe failed liver development in response to reduced SMN levels, in a mouse model of severe SMA. The SMA liver is dark red, small and has: iron deposition; immature sinusoids congested with blood; persistent erythropoietic elements and increased immature red blood cells; increased and persistent megakaryocytes which release high levels of platelets found as clot-like accumulations in the heart. Myelopoiesis in contrast, was unaffected. Further analysis revealed significant molecular changes in SMA liver, consistent with the morphological findings. Antisense treatment from birth with PMO25, increased lifespan and ameliorated all morphological defects in liver by postnatal day 21. Defects in the liver are evident at birth, prior to motor system pathology, and impair essential liver function in SMA. Liver is a key recipient of SMA therapies, and systemically delivered antisense treatment, completely rescued liver pathology. Liver therefore, represents an important therapeutic target in SMA.
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Affiliation(s)
- Eva Szunyogova
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
- Euan MacDonald Center for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Haiyan Zhou
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Gillian K. Maxwell
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
| | - Rachael A. Powis
- Euan MacDonald Center for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- Center for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Muntoni Francesco
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Thomas H. Gillingwater
- Euan MacDonald Center for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- Center for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Simon H. Parson
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
- Euan MacDonald Center for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
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87
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Systemic peptide-mediated oligonucleotide therapy improves long-term survival in spinal muscular atrophy. Proc Natl Acad Sci U S A 2016; 113:10962-7. [PMID: 27621445 DOI: 10.1073/pnas.1605731113] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The development of antisense oligonucleotide therapy is an important advance in the identification of corrective therapy for neuromuscular diseases, such as spinal muscular atrophy (SMA). Because of difficulties of delivering single-stranded oligonucleotides to the CNS, current approaches have been restricted to using invasive intrathecal single-stranded oligonucleotide delivery. Here, we report an advanced peptide-oligonucleotide, Pip6a-morpholino phosphorodiamidate oligomer (PMO), which demonstrates potent efficacy in both the CNS and peripheral tissues in severe SMA mice following systemic administration. SMA results from reduced levels of the ubiquitously expressed survival motor neuron (SMN) protein because of loss-of-function mutations in the SMN1 gene. Therapeutic splice-switching oligonucleotides (SSOs) modulate exon 7 splicing of the nearly identical SMN2 gene to generate functional SMN protein. Pip6a-PMO yields SMN expression at high efficiency in peripheral and CNS tissues, resulting in profound phenotypic correction at doses an order-of-magnitude lower than required by standard naked SSOs. Survival is dramatically extended from 12 d to a mean of 456 d, with improvement in neuromuscular junction morphology, down-regulation of transcripts related to programmed cell death in the spinal cord, and normalization of circulating insulin-like growth factor 1. The potent systemic efficacy of Pip6a-PMO, targeting both peripheral as well as CNS tissues, demonstrates the high clinical potential of peptide-PMO therapy for SMA.
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88
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Hosseinibarkooie S, Peters M, Torres-Benito L, Rastetter R, Hupperich K, Hoffmann A, Mendoza-Ferreira N, Kaczmarek A, Janzen E, Milbradt J, Lamkemeyer T, Rigo F, Bennett C, Guschlbauer C, Büschges A, Hammerschmidt M, Riessland M, Kye M, Clemen C, Wirth B. The Power of Human Protective Modifiers: PLS3 and CORO1C Unravel Impaired Endocytosis in Spinal Muscular Atrophy and Rescue SMA Phenotype. Am J Hum Genet 2016; 99:647-665. [PMID: 27499521 DOI: 10.1016/j.ajhg.2016.07.014] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 07/14/2016] [Indexed: 12/13/2022] Open
Abstract
Homozygous loss of SMN1 causes spinal muscular atrophy (SMA), the most common and devastating childhood genetic motor-neuron disease. The copy gene SMN2 produces only ∼10% functional SMN protein, insufficient to counteract development of SMA. In contrast, the human genetic modifier plastin 3 (PLS3), an actin-binding and -bundling protein, fully protects against SMA in SMN1-deleted individuals carrying 3-4 SMN2 copies. Here, we demonstrate that the combinatorial effect of suboptimal SMN antisense oligonucleotide treatment and PLS3 overexpression-a situation resembling the human condition in asymptomatic SMN1-deleted individuals-rescues survival (from 14 to >250 days) and motoric abilities in a severe SMA mouse model. Because PLS3 knockout in yeast impairs endocytosis, we hypothesized that disturbed endocytosis might be a key cellular mechanism underlying impaired neurotransmission and neuromuscular junction maintenance in SMA. Indeed, SMN deficit dramatically reduced endocytosis, which was restored to normal levels by PLS3 overexpression. Upon low-frequency electro-stimulation, endocytotic FM1-43 (SynaptoGreen) uptake in the presynaptic terminal of neuromuscular junctions was restored to control levels in SMA-PLS3 mice. Moreover, proteomics and biochemical analysis revealed CORO1C, another F-actin binding protein, whose direct binding to PLS3 is dependent on calcium. Similar to PLS3 overexpression, CORO1C overexpression restored fluid-phase endocytosis in SMN-knockdown cells by elevating F-actin amounts and rescued the axonal truncation and branching phenotype in Smn-depleted zebrafish. Our findings emphasize the power of genetic modifiers to unravel the cellular pathomechanisms underlying SMA and the power of combinatorial therapy based on splice correction of SMN2 and endocytosis improvement to efficiently treat SMA.
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89
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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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90
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Modified Antisense Oligonucleotides and Their Analogs in Therapy of Neuromuscular Diseases. ACTA ACUST UNITED AC 2016. [DOI: 10.1007/978-3-319-34175-0_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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91
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Osman EY, Washington CW, Kaifer KA, Mazzasette C, Patitucci TN, Florea KM, Simon ME, Ko CP, Ebert AD, Lorson CL. Optimization of Morpholino Antisense Oligonucleotides Targeting the Intronic Repressor Element1 in Spinal Muscular Atrophy. Mol Ther 2016; 24:1592-601. [PMID: 27401142 DOI: 10.1038/mt.2016.145] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/04/2016] [Indexed: 12/13/2022] Open
Abstract
Loss of Survival Motor Neuron-1 (SMN1) causes Spinal Muscular Atrophy, a devastating neurodegenerative disease. SMN2 is a nearly identical copy gene; however SMN2 cannot prevent disease development in the absence of SMN1 since the majority of SMN2-derived transcripts are alternatively spliced, encoding a truncated, unstable protein lacking exon 7. Nevertheless, SMN2 retains the ability to produce low levels of functional protein. Previously we have described a splice-switching Morpholino antisense oligonucleotide (ASO) sequence that targets a potent intronic repressor, Element1 (E1), located upstream of SMN2 exon 7. In this study, we have assessed a novel panel of Morpholino ASOs with the goal of optimizing E1 ASO activity. Screening for efficacy in the SMNΔ7 mouse model, a single ASO variant was more active in vivo compared with the original E1(MO)-ASO. Sequence variant eleven (E1(MOv11)) consistently showed greater efficacy by increasing the lifespan of severe Spinal Muscular Atrophy mice after a single intracerebroventricular injection in the central nervous system, exhibited a strong dose-response across an order of magnitude, and demonstrated excellent target engagement by partially reversing the pathogenic SMN2 splicing event. We conclude that Morpholino modified ASOs are effective in modifying SMN2 splicing and have the potential for future Spinal Muscular Atrophy clinical applications.
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Affiliation(s)
- Erkan Y Osman
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Charles W Washington
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Kevin A Kaifer
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA.,Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, Missouri, USA
| | - Chiara Mazzasette
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Teresa N Patitucci
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Kyra M Florea
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA.,Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, Missouri, USA
| | - Madeline E Simon
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA.,Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, Missouri, USA
| | - Chien-Ping Ko
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Allison D Ebert
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Christian L Lorson
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA.,Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, Missouri, USA
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92
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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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93
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Catapano F, Zaharieva I, Scoto M, Marrosu E, Morgan J, Muntoni F, Zhou H. Altered Levels of MicroRNA-9, -206, and -132 in Spinal Muscular Atrophy and Their Response to Antisense Oligonucleotide Therapy. MOLECULAR THERAPY. NUCLEIC ACIDS 2016; 5:e331. [PMID: 27377135 PMCID: PMC5014531 DOI: 10.1038/mtna.2016.47] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/25/2016] [Indexed: 12/12/2022]
Abstract
The identification of noninvasive biomarkers to monitor the disease progression in spinal muscular atrophy (SMA) is becoming increasingly important. MicroRNAs (miRNAs) regulate gene expression and are implicated in the pathogenesis of neuromuscular diseases, including motor neuron degeneration. In this study, we selectively characterized the expression of miR-9, miR-206, and miR-132 in spinal cord, skeletal muscle, and serum from SMA transgenic mice, and in serum from SMA patients. A systematic analysis of miRNA expression was conducted in SMA mice with different disease severities (severe type I-like and mild type III-like) at different disease stages (pre-, mid-, and late-symptomatic stages), and in morpholino antisense oligonucleotide-treated mice. There was differential expression of all three miRNAs in spinal cord, skeletal muscle and serum samples in SMA mice. Serum miRNAs were altered prior to the changes in spinal cord and skeletal muscle at the presymptomatic stage. The altered miR-132 levels in spinal cord, muscle, and serum transiently reversed to normal level after a single-dose morpholino antisense oligomer PMO25 treatment in SMA mice. We also confirmed a significant alteration of miR-9 and miR-132 level in serum samples from SMA patients. Our study indicates the potential of developing miRNAs as noninvasive biomarkers in SMA.
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Affiliation(s)
- Francesco Catapano
- Dubowitz Neuromuscular Centre and Developmental Neuroscience Programme, Institute of Child Health, University College London, London, UK
| | - Irina Zaharieva
- Dubowitz Neuromuscular Centre and Developmental Neuroscience Programme, Institute of Child Health, University College London, London, UK
| | - Mariacristina Scoto
- Dubowitz Neuromuscular Centre and Developmental Neuroscience Programme, Institute of Child Health, University College London, London, UK
| | - Elena Marrosu
- Dubowitz Neuromuscular Centre and Developmental Neuroscience Programme, Institute of Child Health, University College London, London, UK
| | - Jennifer Morgan
- Dubowitz Neuromuscular Centre and Developmental Neuroscience Programme, Institute of Child Health, University College London, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre and Developmental Neuroscience Programme, Institute of Child Health, University College London, London, UK
| | - Haiyan Zhou
- Dubowitz Neuromuscular Centre and Developmental Neuroscience Programme, Institute of Child Health, University College London, London, UK
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94
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Burns JK, Kothary R, Parks RJ. Opening the window: The case for carrier and perinatal screening for spinal muscular atrophy. Neuromuscul Disord 2016; 26:551-9. [PMID: 27460292 DOI: 10.1016/j.nmd.2016.06.459] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 06/20/2016] [Accepted: 06/21/2016] [Indexed: 11/26/2022]
Abstract
Spinal muscular atrophy (SMA) is the most common genetically inherited neurodegenerative disease that leads to infant mortality worldwide. SMA is caused by genetic deletion or mutation in the survival of motor neuron 1 (SMN1) gene, which results in a deficiency in SMN protein. For reasons that are still unclear, SMN protein deficiency predominantly affects α-motor neurons, resulting in their degeneration and subsequent paralysis of limb and trunk muscles, progressing to death in severe cases. Emerging evidence suggests that SMN protein deficiency also affects the heart, autonomic nervous system, skeletal muscle, liver, pancreas and perhaps many other organs. Currently, there is no cure for SMA. Patient treatment includes respiratory care, physiotherapy, and nutritional management, which can somewhat ameliorate disease symptoms and increase life span. Fortunately, several novel therapies have advanced to human clinical trials. However, data from studies in animal models of SMA indicate that the greatest therapeutic benefit is achieved through initiating treatment as early as possible, before widespread loss of motor neurons has occurred. In this review, we discuss the merit of carrier and perinatal patient screening for SMA considering the efficacy of emerging therapeutics and the physical, emotional and financial burden of the disease on affected families and society.
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Affiliation(s)
- Joseph K Burns
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada; Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Canada; University of Ottawa Centre for Neuromuscular Disease, Ottawa, Canada
| | - Rashmi Kothary
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada; University of Ottawa Centre for Neuromuscular Disease, Ottawa, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada; Department of Medicine, University of Ottawa, Ottawa, Canada
| | - Robin J Parks
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada; Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Canada; University of Ottawa Centre for Neuromuscular Disease, Ottawa, Canada; Department of Medicine, University of Ottawa, Ottawa, Canada.
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95
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Havens MA, Hastings ML. Splice-switching antisense oligonucleotides as therapeutic drugs. Nucleic Acids Res 2016; 44:6549-63. [PMID: 27288447 PMCID: PMC5001604 DOI: 10.1093/nar/gkw533] [Citation(s) in RCA: 290] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 06/02/2016] [Indexed: 01/09/2023] Open
Abstract
Splice-switching oligonucleotides (SSOs) are short, synthetic, antisense, modified nucleic acids that base-pair with a pre-mRNA and disrupt the normal splicing repertoire of the transcript by blocking the RNA–RNA base-pairing or protein–RNA binding interactions that occur between components of the splicing machinery and the pre-mRNA. Splicing of pre-mRNA is required for the proper expression of the vast majority of protein-coding genes, and thus, targeting the process offers a means to manipulate protein production from a gene. Splicing modulation is particularly valuable in cases of disease caused by mutations that lead to disruption of normal splicing or when interfering with the normal splicing process of a gene transcript may be therapeutic. SSOs offer an effective and specific way to target and alter splicing in a therapeutic manner. Here, we discuss the different approaches used to target and alter pre-mRNA splicing with SSOs. We detail the modifications to the nucleic acids that make them promising therapeutics and discuss the challenges to creating effective SSO drugs. We highlight the development of SSOs designed to treat Duchenne muscular dystrophy and spinal muscular atrophy, which are currently being tested in clinical trials.
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Affiliation(s)
- Mallory A Havens
- Department of Biology, Lewis University, Romeoville, IL 60446, USA
| | - Michelle L Hastings
- Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
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96
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Sintusek P, Catapano F, Angkathunkayul N, Marrosu E, Parson SH, Morgan JE, Muntoni F, Zhou H. Histopathological Defects in Intestine in Severe Spinal Muscular Atrophy Mice Are Improved by Systemic Antisense Oligonucleotide Treatment. PLoS One 2016; 11:e0155032. [PMID: 27163330 PMCID: PMC4862622 DOI: 10.1371/journal.pone.0155032] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 04/22/2016] [Indexed: 12/28/2022] Open
Abstract
Gastrointestinal (GI) defects, including gastroesophageal reflux, constipation and delayed gastric emptying, are common in patients with spinal muscular atrophy (SMA). Similar GI dysmotility has been identified in mouse models with survival of motor neuron (SMN) protein deficiency. We previously described vascular defects in skeletal muscle and spinal cord of SMA mice and we hypothesized that similar defects could be involved in the GI pathology observed in these mice. We therefore investigated the gross anatomical structure, enteric vasculature and neurons in the small intestine in a severe mouse model of SMA. We also assessed the therapeutic response of GI histopathology to systemic administration of morpholino antisense oligonucleotide (AON) designed to increase SMN protein expression. Significant anatomical and histopathological abnormalities, with striking reduction of vascular density, overabundance of enteric neurons and increased macrophage infiltration, were detected in the small intestine in SMA mice. After systemic AON treatment in neonatal mice, all the abnormalities observed were significantly restored to near-normal levels. We conclude that the observed GI histopathological phenotypes and functional defects observed in these SMA mice are strongly linked to SMN deficiency which can be rescued by systemic administration of AON. This study on the histopathological changes in the gastrointestinal system in severe SMA mice provides further indication of the complex role that SMN plays in multiple tissues and suggests that at least in SMA mice restoration of SMN production in peripheral tissues is essential for optimal outcome.
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MESH Headings
- Animals
- Animals, Newborn
- Disease Models, Animal
- Gene Expression
- Genetic Therapy/methods
- Heterozygote
- Homozygote
- Humans
- Injections, Subcutaneous
- Intestine, Small/blood supply
- Intestine, Small/drug effects
- Intestine, Small/innervation
- Intestine, Small/pathology
- Macrophages/drug effects
- Macrophages/metabolism
- Macrophages/pathology
- Mice
- Mice, Transgenic
- Morpholinos/administration & dosage
- Motor Neurons/drug effects
- Motor Neurons/metabolism
- Motor Neurons/pathology
- Muscular Atrophy, Spinal/genetics
- Muscular Atrophy, Spinal/metabolism
- Muscular Atrophy, Spinal/pathology
- Muscular Atrophy, Spinal/therapy
- Oligonucleotides, Antisense/administration & dosage
- Phenotype
- Spinal Cord/blood supply
- Spinal Cord/drug effects
- Spinal Cord/pathology
- Survival of Motor Neuron 1 Protein/agonists
- Survival of Motor Neuron 1 Protein/genetics
- Survival of Motor Neuron 1 Protein/metabolism
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Affiliation(s)
- Palittiya Sintusek
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
- Division of Gastroenterology and Hepatology, Department of Pediatrics, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, Thailand
| | - Francesco Catapano
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Napat Angkathunkayul
- Department of Pathology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Elena Marrosu
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Simon H. Parson
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
- Euan MacDonald Center for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Jennifer E. Morgan
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
- * E-mail: (HZ); (FM)
| | - Haiyan Zhou
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom
- * E-mail: (HZ); (FM)
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97
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Butchbach MER, Lumpkin CJ, Harris AW, Saieva L, Edwards JD, Workman E, Simard LR, Pellizzoni L, Burghes AHM. Protective effects of butyrate-based compounds on a mouse model for spinal muscular atrophy. Exp Neurol 2016; 279:13-26. [PMID: 26892876 PMCID: PMC4834225 DOI: 10.1016/j.expneurol.2016.02.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 02/11/2016] [Accepted: 02/13/2016] [Indexed: 11/17/2022]
Abstract
Proximal spinal muscular atrophy (SMA) is a childhood-onset degenerative disease resulting from the selective loss of motor neurons in the spinal cord. SMA is caused by the loss of SMN1 (survival motor neuron 1) but retention of SMN2. The number of copies of SMN2 modifies disease severity in SMA patients as well as in mouse models, making SMN2 a target for therapeutics development. Sodium butyrate (BA) and its analog (4PBA) have been shown to increase SMN2 expression in SMA cultured cells. In this study, we examined the effects of BA, 4PBA as well as two BA prodrugs-glyceryl tributyrate (BA3G) and VX563-on the phenotype of SMNΔ7 SMA mice. Treatment with 4PBA, BA3G and VX563 but not BA beginning at PND04 significantly improved the lifespan and delayed disease end stage, with administration of VX563 also improving the growth rate of these mice. 4PBA and VX563 improved the motor phenotype of SMNΔ7 SMA mice and prevented spinal motor neuron loss. Interestingly, neither 4PBA nor VX563 had an effect on SMN expression in the spinal cords of treated SMNΔ7 SMA mice; however, they inhibited histone deacetylase (HDAC) activity and restored the normal phosphorylation states of Akt and glycogen synthase kinase 3β, both of which are altered by SMN deficiency in vivo. These observations show that BA-based compounds with favorable pharmacokinetics ameliorate SMA pathology possibly by modulating HDAC and Akt signaling.
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Affiliation(s)
- Matthew E R Butchbach
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA; Center for Pediatric Research, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA; Department of Pediatrics, Thomas Jefferson University, Philadelphia, PA, USA; Department of Biological Sciences, University of Delaware, Newark, DE, USA.
| | - Casey J Lumpkin
- Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA; Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - Ashlee W Harris
- Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Luciano Saieva
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Jonathan D Edwards
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Eileen Workman
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Louise R Simard
- Department of Biochemistry and Medical Genetics, University of Manitoba Faculty of Health Sciences, Winnipeg, Manitoba, Canada
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Arthur H M Burghes
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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98
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Lin TL, Chen TH, Hsu YY, Cheng YH, Juang BT, Jong YJ. Selective Neuromuscular Denervation in Taiwanese Severe SMA Mouse Can Be Reversed by Morpholino Antisense Oligonucleotides. PLoS One 2016; 11:e0154723. [PMID: 27124114 PMCID: PMC4849667 DOI: 10.1371/journal.pone.0154723] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 04/18/2016] [Indexed: 11/27/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease caused by deficiency of the survival of motor neuron (SMN) protein, which leads to synaptic defects and spinal motor neuron death. Neuromuscular junction (NMJ) abnormalities have been found to be involved in SMA pathogenesis in the SMNΔ7 SMA mouse model. However, whether similar NMJ pathological findings present in another commonly used mouse model, the Taiwanese SMA mouse, has not been fully investigated. To examine the NMJs of the Taiwanese severe SMA mouse model (Smn-/-; SMN2tg/0), which is characterized by severe phenotype and death before postnatal day (P) 9, we investigated 25 axial and appendicular muscles from P1 to P9. We labelled the muscles with anti-neurofilament and anti-synaptophysin antibodies for nerve terminals and α-bungarotoxin for acetylcholine receptors (AChRs). We found that severe NMJ denervation (<50% fully innervated endplates) selectively occurred in the flexor digitorum brevis 2 and 3 (FDB-2/3) muscles from P5, and an increased percentage of fully denervated endplates correlated with SMA progression. Furthermore, synaptophysin signals were absent at the endplate compared to control littermate mice, suggesting that vesicle transport might only be affected at the end stage. Subsequently, we treated the Taiwanese severe SMA mice with morpholino (MO) antisense oligonucleotides (80 μg/g) via subcutaneous injection at P0. We found that MO significantly reversed the NMJ denervation in FDB-2/3 muscles and extended the survival of Taiwanese severe SMA mice. We conclude that early NMJ denervation in the FDB-2/3 muscles of Taiwanese severe SMA mice can be reversed by MO treatment. The FDB-2/3 muscles of Taiwanese severe SMA mice provide a very sensitive platform for assessing the effectiveness of drug treatments in SMA preclinical studies.
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Affiliation(s)
- Te-Lin Lin
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Tai-Heng Chen
- Division of Pediatric Emergency, Department of Emergency, Kaohsiung Medical University and Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Ya-Yun Hsu
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Hua Cheng
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Bi-Tzen Juang
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
| | - Yuh-Jyh Jong
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Institute of Molecular Medicine and Bioengineering, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
- Departments of Pediatrics and Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
- * E-mail: ;
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99
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Simone C, Ramirez A, Bucchia M, Rinchetti P, Rideout H, Papadimitriou D, Re DB, Corti S. Is spinal muscular atrophy a disease of the motor neurons only: pathogenesis and therapeutic implications? Cell Mol Life Sci 2016; 73:1003-20. [PMID: 26681261 PMCID: PMC4756905 DOI: 10.1007/s00018-015-2106-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 01/16/2023]
Abstract
Spinal muscular atrophy (SMA) is a genetic neurological disease that causes infant mortality; no effective therapies are currently available. SMA is due to homozygous mutations and/or deletions in the survival motor neuron 1 gene and subsequent reduction of the SMN protein, leading to the death of motor neurons. However, there is increasing evidence that in addition to motor neurons, other cell types are contributing to SMA pathology. In this review, we will discuss the involvement of non-motor neuronal cells, located both inside and outside the central nervous system, in disease onset and progression. Even if SMN restoration in motor neurons is needed, it has been shown that optimal phenotypic amelioration in animal models of SMA requires a more widespread SMN correction. It has been demonstrated that non-motor neuronal cells are also involved in disease pathogenesis and could have important therapeutic implications. For these reasons it will be crucial to take this evidence into account for the clinical translation of the novel therapeutic approaches.
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Affiliation(s)
- Chiara Simone
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Agnese Ramirez
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Monica Bucchia
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Paola Rinchetti
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Hardy Rideout
- Division of Basic Neurosciences, Biomedical Research Foundation of the Academy of Athens (BRFAA), Soranou Efesiou 4, 115 27, Athens, Greece
| | - Dimitra Papadimitriou
- Division of Basic Neurosciences, Biomedical Research Foundation of the Academy of Athens (BRFAA), Soranou Efesiou 4, 115 27, Athens, Greece
| | - Diane B Re
- Department of Environmental Health Sciences, Columbia University, New York, NY, 10032, USA
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY, 10032, USA
| | - Stefania Corti
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy.
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100
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Zhao X, Feng Z, Ling KKY, Mollin A, Sheedy J, Yeh S, Petruska J, Narasimhan J, Dakka A, Welch EM, Karp G, Chen KS, Metzger F, Ratni H, Lotti F, Tisdale S, Naryshkin NA, Pellizzoni L, Paushkin S, Ko CP, Weetall M. Pharmacokinetics, pharmacodynamics, and efficacy of a small-molecule SMN2 splicing modifier in mouse models of spinal muscular atrophy. Hum Mol Genet 2016; 25:1885-1899. [PMID: 26931466 PMCID: PMC5062580 DOI: 10.1093/hmg/ddw062] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/22/2016] [Indexed: 12/26/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by the loss or mutation of both copies of the survival motor neuron 1 (SMN1) gene. The related SMN2 gene is retained, but due to alternative splicing of exon 7, produces insufficient levels of the SMN protein. Here, we systematically characterize the pharmacokinetic and pharmacodynamics properties of the SMN splicing modifier SMN-C1. SMN-C1 is a low-molecular weight compound that promotes the inclusion of exon 7 and increases production of SMN protein in human cells and in two transgenic mouse models of SMA. Furthermore, increases in SMN protein levels in peripheral blood mononuclear cells and skin correlate with those in the central nervous system (CNS), indicating that a change of these levels in blood or skin can be used as a non-invasive surrogate to monitor increases of SMN protein levels in the CNS. Consistent with restored SMN function, SMN-C1 treatment increases the levels of spliceosomal and U7 small-nuclear RNAs and corrects RNA processing defects induced by SMN deficiency in the spinal cord of SMNΔ7 SMA mice. A 100% or greater increase in SMN protein in the CNS of SMNΔ7 SMA mice robustly improves the phenotype. Importantly, a ∼50% increase in SMN leads to long-term survival, but the SMA phenotype is only partially corrected, indicating that certain SMA disease manifestations may respond to treatment at lower doses. Overall, we provide important insights for the translation of pre-clinical data to the clinic and further therapeutic development of this series of molecules for SMA treatment.
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Affiliation(s)
- Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Zhihua Feng
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Karen K Y Ling
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Anna Mollin
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | - Shirley Yeh
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | | | - Amal Dakka
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Ellen M Welch
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Gary Karp
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Karen S Chen
- SMA Foundation, 888 Seventh Avenue, Suite 400, New York, NY 10019, USA
| | - Friedrich Metzger
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, Basel 4070, Switzerland
| | - Hasane Ratni
- F. Hoffmann-La Roche, Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Grenzacherstrasse 124, Basel 4070, Switzerland
| | - Francesco Lotti
- Department of Pathology and Cell Biology, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA and
| | - Sarah Tisdale
- Department of Pathology and Cell Biology, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA and
| | | | - Livio Pellizzoni
- Department of Pathology and Cell Biology, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA and
| | - Sergey Paushkin
- SMA Foundation, 888 Seventh Avenue, Suite 400, New York, NY 10019, USA
| | - Chien-Ping Ko
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA,
| | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA,
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