1
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Cottam NC, Harrington MA, Schork PM, Sun J. No significant sex differences in incidence or phenotype for the SMNΔ7 mouse model of spinal muscular atrophy. Neuromuscul Disord 2024; 37:13-22. [PMID: 38493520 PMCID: PMC11031329 DOI: 10.1016/j.nmd.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 02/29/2024] [Accepted: 03/04/2024] [Indexed: 03/19/2024]
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive disease that affects 1 out of every 6,000-10,000 individuals at birth, making it the leading genetic cause of infant mortality. In recent years, reports of sex differences in SMA patients have become noticeable. The SMNΔ7 mouse model is commonly used to investigate pathologies and treatments in SMA. However, studies on sex as a contributing biological variable are few and dated. Here, we rigorously investigated the effect of sex on a series of characteristics in SMA mice of the SMNΔ7 model. Incidence and lifespan of 23 mouse litters were tracked and phenotypic assessments were performed at 2-day intervals starting at postnatal day 6 for every pup until the death of the SMA pup(s) in each litter. Brain weights were also collected post-mortem. We found that male and female SMA incidence does not differ significantly, survival periods are the same across sexes, and there was no phenotypic difference between male and female SMA pups, other than for females exhibiting lesser body weights at early ages. Overall, this study ensures that sex is not a biological variable that contributes to the incidence ratio or disease severity in the SMNΔ7 mouse model.
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Affiliation(s)
- Nicholas C Cottam
- Delaware State University, Department of Biological Sciences, 1200 N Dupont Highway, Dover, DE, USA
| | - Melissa A Harrington
- Delaware Center for Neuroscience Research, Delaware State University, Dover, DE, USA
| | - Pamela M Schork
- Delaware State University, Department of Biological Sciences, 1200 N Dupont Highway, Dover, DE, USA
| | - Jianli Sun
- Delaware State University, Department of Biological Sciences, 1200 N Dupont Highway, Dover, DE, USA; Delaware Center for Neuroscience Research, Delaware State University, Dover, DE, USA.
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2
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Crisafulli S, Boccanegra B, Vitturi G, Trifirò G, De Luca A. Pharmacological Therapies of Spinal Muscular Atrophy: A Narrative Review of Preclinical, Clinical-Experimental, and Real-World Evidence. Brain Sci 2023; 13:1446. [PMID: 37891814 PMCID: PMC10605203 DOI: 10.3390/brainsci13101446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/09/2023] [Accepted: 10/10/2023] [Indexed: 10/29/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a rare neuromuscular disease, with an estimated incidence of about 1 in 10,000 live births. To date, three orphan drugs have been approved for the treatment of SMA: nusinersen, onasemnogene abeparvovec, and risdiplam. The aim of this narrative review was to provide an overview of the pre- and post-marketing evidence on the pharmacological treatments approved for the treatment of SMA by identifying preclinical and clinical studies registered in clinicaltrials.gov and in the EU PAS register from their inception until the 4 January 2023. The preclinical evidence on the drugs approved for SMA allowed a significant acceleration in the experimental phase of these drugs. However, since these drugs had been authorized through accelerated programs, the conduction of post-marketing studies was requested as a condition of their marketing approval to better understand their risk-benefit profiles in real-world settings. As of the 4 January 2023, a total of 69 post-marketing studies concerning the three orphan drugs approved for SMA were identified in clinicaltrials.gov (N = 65; 94.2%) and in the EU PAS register (N = 4; 5.8%). Currently, ongoing studies are primarily aimed at providing evidence concerning the risk-benefit profile of the three drugs in specific populations that were not included in the pivotal trials and to investigate the long-term safety and clinical benefits of these drugs. Real-world data sources collecting information regarding the natural history of the disease and post-marketing surveillance of the available therapies are increasingly becoming essential for generating real-world evidence on this rare disease and its orphan drugs.
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Affiliation(s)
- Salvatore Crisafulli
- Department of Medicine, University of Verona, Piazzale Ludovico Antonio Scuro 10, 37124 Verona, Italy;
| | - Brigida Boccanegra
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, Via E. Orabona 4, 70125 Bari, Italy; (B.B.); (A.D.L.)
| | - Giacomo Vitturi
- Department of Diagnostics and Public Health, University of Verona, Piazzale Ludovico Antonio Scuro 10, 37124 Verona, Italy;
| | - Gianluca Trifirò
- Department of Diagnostics and Public Health, University of Verona, Piazzale Ludovico Antonio Scuro 10, 37124 Verona, Italy;
| | - Annamaria De Luca
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, Via E. Orabona 4, 70125 Bari, Italy; (B.B.); (A.D.L.)
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3
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Cottam NC, Bamfo T, Harrington MA, Charvet CJ, Hekmatyar K, Tulin N, Sun J. Cerebellar structural, astrocytic, and neuronal abnormalities in the SMNΔ7 mouse model of spinal muscular atrophy. Brain Pathol 2023; 33:e13162. [PMID: 37218083 PMCID: PMC10467044 DOI: 10.1111/bpa.13162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 04/18/2023] [Indexed: 05/24/2023] Open
Abstract
Spinalmuscular atrophy (SMA) is a neuromuscular disease that affects as many as 1 in 6000 individuals at birth, making it the leading genetic cause of infant mortality. A growing number of studies indicate that SMA is a multi-system disease. The cerebellum has received little attention even though it plays an important role in motor function and widespread pathology has been reported in the cerebella of SMA patients. In this study, we assessed SMA pathology in the cerebellum using structural and diffusion magnetic resonance imaging, immunohistochemistry, and electrophysiology with the SMNΔ7 mouse model. We found a significant disproportionate loss in cerebellar volume, decrease in afferent cerebellar tracts, selective lobule-specific degeneration of Purkinje cells, abnormal lobule foliation and astrocyte integrity, and a decrease in spontaneous firing of cerebellar output neurons in the SMA mice compared to controls. Our data suggest that defects in cerebellar structure and function due to decreased survival motor neuron (SMN) levels impair the functional cerebellar output affecting motor control, and that cerebellar pathology should be addressed to achieve comprehensive treatment and therapy for SMA patients.
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Affiliation(s)
- Nicholas C. Cottam
- Department of Biological SciencesDelaware State UniversityDoverDelawareUSA
| | - Tiffany Bamfo
- Department of Biological SciencesDelaware State UniversityDoverDelawareUSA
| | | | - Christine J. Charvet
- Delaware Center for Neuroscience ResearchDelaware State UniversityDoverDelawareUSA
- Department of Anatomy, Physiology and PharmacologyAuburn UniversityAuburnAlabamaUSA
- Department of PsychologyDelaware State UniversityDoverDEUnited States
| | - Khan Hekmatyar
- Center for Biomedical and Brain ImagingUniversity of DelawareNewarkDelawareUSA
- Bioimaging Research Center for Biomedical and Brain ImagingUniversity of GeorgiaAthensGeorgiaUSA
| | - Nikita Tulin
- Department of NeuroscienceTemple UniversityPhiladelphiaPennsylvaniaUSA
| | - Jianli Sun
- Department of Biological SciencesDelaware State UniversityDoverDelawareUSA
- Delaware Center for Neuroscience ResearchDelaware State UniversityDoverDelawareUSA
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4
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Buchner F, Dokuzluoglu Z, Grass T, Rodriguez-Muela N. Spinal Cord Organoids to Study Motor Neuron Development and Disease. Life (Basel) 2023; 13:1254. [PMID: 37374039 DOI: 10.3390/life13061254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 05/18/2023] [Indexed: 06/29/2023] Open
Abstract
Motor neuron diseases (MNDs) are a heterogeneous group of disorders that affect the cranial and/or spinal motor neurons (spMNs), spinal sensory neurons and the muscular system. Although they have been investigated for decades, we still lack a comprehensive understanding of the underlying molecular mechanisms; and therefore, efficacious therapies are scarce. Model organisms and relatively simple two-dimensional cell culture systems have been instrumental in our current knowledge of neuromuscular disease pathology; however, in the recent years, human 3D in vitro models have transformed the disease-modeling landscape. While cerebral organoids have been pursued the most, interest in spinal cord organoids (SCOs) is now also increasing. Pluripotent stem cell (PSC)-based protocols to generate SpC-like structures, sometimes including the adjacent mesoderm and derived skeletal muscle, are constantly being refined and applied to study early human neuromuscular development and disease. In this review, we outline the evolution of human PSC-derived models for generating spMN and recapitulating SpC development. We also discuss how these models have been applied to exploring the basis of human neurodevelopmental and neurodegenerative diseases. Finally, we provide an overview of the main challenges to overcome in order to generate more physiologically relevant human SpC models and propose some exciting new perspectives.
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Affiliation(s)
- Felix Buchner
- German Center for Neurodegenerative Diseases, 01307 Dresden, Germany
| | | | - Tobias Grass
- German Center for Neurodegenerative Diseases, 01307 Dresden, Germany
| | - Natalia Rodriguez-Muela
- German Center for Neurodegenerative Diseases, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, 01307 Dresden, Germany
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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5
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Spinal muscular atrophy: Where are we now? Current challenges and high hopes. POSTEP HIG MED DOSW 2022. [DOI: 10.2478/ahem-2022-0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by muscle weakness. It causes movement issues and severe physical disability. SMA is classified into four types based on the level of function achieved, age of onset, and maximum function achieved. The deletion or point mutation in the Survival of Motor Neuron 1 (SMN1) gene causes SMA. As a result, no full-length protein is produced. A nearly identical paralog, SMN2, provides enough stable protein to prevent death but not enough to compensate for SMN1's loss. The difference between SMN1 and SMN2 is due to different exon 7 alternative splicing patterns. SMA molecular therapies currently focus on restoring functional SMN protein by splicing modification of SMN2 exon 7 or elevated SMN protein levels. Nusinersen, an antisense oligonucleotide targeting the ISS-N1 sequence in SMN2 intron 7, was the first drug approved by the Food and Drug Administration. Risdiplam, a novel therapeutic that acts as an SMN2 exon 7 splicing modifier, was recently approved. All of these drugs result in the inclusion of SMN2 exon 7, and thus the production of functional SMN protein. Onasemnogene abeparvovec is a gene therapy that uses a recombinant adeno-associated virus that encodes the SMN protein. There are also experimental therapies available, such as reldesemtiv and apitegromab (SRK-015), which focus on improving muscle function or increasing muscle tissue growth, respectively. Although approved therapies have been shown to be effective, not all SMA patients can benefit from them due to age or weight, but primarily due to their high cost. This demonstrates the significance of continuous treatment improvement in today's medical challenges.
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Tay SH, Ellieyana EN, Le Y, Sarusie MV, Grimm C, Ohmer J, Mathuru A, Fischer U, Winkler C. A novel zebrafish model for intermediate type spinal muscular atrophy demonstrates importance of Smn for maintenance of mature motor neurons. Hum Mol Genet 2021; 30:2488-2502. [PMID: 34302176 DOI: 10.1093/hmg/ddab212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/09/2021] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
A deficiency in Survival Motor Neuron (SMN) protein results in motor neuron loss in spinal muscular atrophy (SMA) patients. Human SMN is encoded by SMN1 and SMN2 that differ by a single C6T transition in a splice regulatory region of exon 7. In SMN2, exon 7 is skipped leading to an unstable protein, which cannot compensate for SMN1 loss in SMA patients. The disease severity of human SMA (Types 1 to 4) depends on the levels of SMN protein, with intermediate levels leading to delayed disease onset and extended life expectancy in Type 2 patients. We used homology directed repair (HDR) to generate a zebrafish mutant with intermediate Smn levels, to mimic intermediate, hSMN2 dependent forms of SMA. In the obtained smnA6Tind27 mutant zebrafish, Smn protein formed oligomers but protein levels dropped significantly at juvenile stages. Motor neurons and neuromuscular junctions (NMJ) also formed normally initially but motor neuron loss and locomotor deficiencies became evident at 21 days. Subsequent muscle wasting and early adult lethality also phenocopied intermediate forms of human SMA. Together, our findings are consistent with the interpretation that Smn is required for neuromuscular maintenance, and establish the smnA6Tind27 zebrafish mutant as a novel model for intermediate types of SMA. As this mutant allows studying the effect of late Smn loss on motor neurons, neuromuscular junctions, and muscle at advanced stages of the disease, it will be a valuable resource for testing new drugs targeted towards treating intermediate forms of SMA.
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Affiliation(s)
- Shermaine Huiping Tay
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Erna Nur Ellieyana
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Yao Le
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Menachem Viktor Sarusie
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Clemens Grimm
- Department of Biochemistry, Biocenter, University of Wuerzburg, 97074 Wuerzburg, Germany
| | - Jürgen Ohmer
- Department of Biochemistry, Biocenter, University of Wuerzburg, 97074 Wuerzburg, Germany
| | - Ajay Mathuru
- Yale-NUS College, 12 College Avenue West, Singapore 138527, Singapore.,Institute of Molecular and Cell Biology, Singapore 138673, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Utz Fischer
- Department of Biochemistry, Biocenter, University of Wuerzburg, 97074 Wuerzburg, Germany
| | - Christoph Winkler
- Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore 117543, Singapore
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7
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Watson KS, Boukhloufi I, Bowerman M, Parson SH. The Relationship between Body Composition, Fatty Acid Metabolism and Diet in Spinal Muscular Atrophy. Brain Sci 2021; 11:brainsci11020131. [PMID: 33498293 PMCID: PMC7909254 DOI: 10.3390/brainsci11020131] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 01/15/2021] [Accepted: 01/17/2021] [Indexed: 12/11/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive condition that results in pathological deficiency of the survival motor neuron (SMN) protein. SMA most frequently presents itself within the first few months of life and is characterized by progressive muscle weakness. As a neuromuscular condition, it prominently affects spinal cord motor neurons and the skeletal muscle they innervate. However, over the past few decades, the SMA phenotype has expanded to include pathologies outside of the neuromuscular system. The current therapeutic SMA landscape is at a turning point, whereby a holistic multi-systemic approach to the understanding of disease pathophysiology is at the forefront of fundamental research and translational endeavours. In particular, there has recently been a renewed interest in body composition and metabolism in SMA patients, specifically that of fatty acids. Indeed, there is increasing evidence of aberrant fat distribution and fatty acid metabolism dysfunction in SMA patients and animal models. This review will explore fatty acid metabolic defects in SMA and discuss how dietary interventions could potentially be used to modulate and reduce the adverse health impacts of these perturbations in SMA patients.
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Affiliation(s)
- Katherine S. Watson
- Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK;
| | - Imane Boukhloufi
- School of Medicine, Keele University, Staffordshire ST5 5BG, UK;
| | - Melissa Bowerman
- School of Medicine, Keele University, Staffordshire ST5 5BG, UK;
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry SY10 7AG, UK
- Correspondence: (M.B.); (S.H.P.)
| | - Simon H. Parson
- Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK;
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh EH16 4SB, UK
- Correspondence: (M.B.); (S.H.P.)
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8
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Wirth B. Spinal Muscular Atrophy: In the Challenge Lies a Solution. Trends Neurosci 2021; 44:306-322. [PMID: 33423791 DOI: 10.1016/j.tins.2020.11.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 11/08/2020] [Accepted: 11/30/2020] [Indexed: 12/16/2022]
Abstract
The path from gene discovery to therapy in spinal muscular atrophy (SMA) has been a highly challenging endeavor, but also led to one of the most successful stories in neurogenetics. In SMA, a neuromuscular disorder with an often fatal outcome until recently, with those affected never able to sit, stand, or walk, children now achieve these motoric abilities and almost age-based development when treated presymptomatically. This review summarizes the challenges along this 30-year journey. It is also meant to inspire early-career scientists not to give up when things become difficult but to try to uncover the biological underpinnings and transform the challenge into the next big discovery. Without doubt, the improvements seen with the three therapeutic strategies in SMA are impressive; many open questions remain and are discussed in this review.
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Affiliation(s)
- Brunhilde Wirth
- Institute of Human Genetics, Center for Molecular Medicine, Center for Rare Disorders, University of Cologne, Kerpener Str. 34, 50931 Cologne, Germany.
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9
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Spinal muscular atrophy: Broad disease spectrum and sex-specific phenotypes. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166063. [PMID: 33412266 DOI: 10.1016/j.bbadis.2020.166063] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/14/2020] [Accepted: 12/21/2020] [Indexed: 12/17/2022]
Abstract
Spinal muscular atrophy (SMA) is one of the major genetic disorders associated with infant mortality. More than 90% of cases of SMA result from deletions of or mutations in the Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, does not compensate for the loss of SMN1 due to predominant skipping of exon 7. The spectrum of SMA is broad, ranging from prenatal death to infant mortality to survival into adulthood. All tissues, including brain, spinal cord, bone, skeletal muscle, heart, lung, liver, pancreas, gastrointestinal tract, kidney, spleen, ovary and testis, are directly and/or indirectly affected in SMA. Accumulating evidence on impaired mitochondrial biogenesis and defects in X chromosome-linked modifying factors, coupled with the sexual dimorphic nature of many tissues, point to sex-specific vulnerabilities in SMA. Here we review the role of sex in the pathogenesis of SMA.
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10
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Fisher EMC, Bannerman DM. Mouse models of neurodegeneration: Know your question, know your mouse. Sci Transl Med 2020; 11:11/493/eaaq1818. [PMID: 31118292 DOI: 10.1126/scitranslmed.aaq1818] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 02/26/2018] [Accepted: 06/19/2018] [Indexed: 12/19/2022]
Abstract
Many mutant mouse strains have been developed as models to investigate neurodegenerative disease in humans. However, variability in results among studies using these mouse strains has led to questions about the value of these models. Here, we appraise various mouse models for dissecting neurodegenerative disease mechanisms and emphasize the importance of asking appropriate research questions. In therapeutic studies, we suggest that understanding variability among and within mouse models is crucial for preventing translational failures in human patients.
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Affiliation(s)
- Elizabeth M C Fisher
- Department of Neuromuscular Diseases, University College London, London WC1N 3BG, UK.
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford OX1 3TA, UK.
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11
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Chang WF, Xu J, Lin TY, Hsu J, Hsieh-Li HM, Hwu YM, Liu JL, Lu CH, Sung LY. Survival Motor Neuron Protein Participates in Mouse Germ Cell Development and Spermatogonium Maintenance. Int J Mol Sci 2020; 21:ijms21030794. [PMID: 31991812 PMCID: PMC7037566 DOI: 10.3390/ijms21030794] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/15/2020] [Accepted: 01/23/2020] [Indexed: 12/13/2022] Open
Abstract
The defective human survival motor neuron 1 (SMN1) gene leads to spinal muscular atrophy (SMA), the most common genetic cause of infant mortality. We previously reported that loss of SMN results in rapid differentiation of Drosophila germline stem cells and mouse embryonic stem cells (ESCs), indicating that SMN also plays important roles in germ cell development and stem cell biology. Here, we show that in healthy mice, SMN is highly expressed in the gonadal tissues, prepubertal spermatogonia, and adult spermatocytes, whereas low SMN expression is found in differentiated spermatid and sperm. In SMA-like mice, the growth of testis tissues is retarded, accompanied with gamete development abnormalities and loss of the spermatogonia-specific marker. Consistently, knockdown of Smn1 in spermatogonial stem cells (SSCs) leads to a compromised regeneration capacity in vitro and in vivo in transplantation experiments. In SMA-like mice, apoptosis and accumulation of the R-loop structure were significantly elevated, indicating that SMN plays a critical role in the survival of male germ cells. The present work demonstrates that SMN, in addition to its critical roles in neuronal development, participates in mouse germ cell and spermatogonium maintenance.
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Affiliation(s)
- Wei-Fang Chang
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan; (W.-F.C.); (T.-Y.L.); (J.H.)
| | - Jie Xu
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical Center, Ann Arbor, MI 48109, USA;
| | - Tzu-Ying Lin
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan; (W.-F.C.); (T.-Y.L.); (J.H.)
| | - Jing Hsu
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan; (W.-F.C.); (T.-Y.L.); (J.H.)
| | - Hsiu-Mei Hsieh-Li
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan;
| | - Yuh-Ming Hwu
- Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei 10449, Taiwan;
- Department of Obstetrics and Gynecology, Mackay Medical College, New Taipei City 252, Taiwan
- Department of Obstetrics and Gynecology, Mackay Junior College of Medicine, Nursing, and Management, Taipei 11260, Taiwan
| | - Ji-Long Liu
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 2JD, UK;
- School of Life Science and Technology, Shanghai Tech University, Shanghai 201210, China
| | - Chung-Hao Lu
- Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei 10449, Taiwan;
- Correspondence: (C.-H.L.); (L.-Y.S.)
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan; (W.-F.C.); (T.-Y.L.); (J.H.)
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
- Animal Resource Center, National Taiwan University, Taipei 106, Taiwan
- Correspondence: (C.-H.L.); (L.-Y.S.)
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12
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Courtney NL, Mole AJ, Thomson AK, Murray LM. Reduced P53 levels ameliorate neuromuscular junction loss without affecting motor neuron pathology in a mouse model of spinal muscular atrophy. Cell Death Dis 2019; 10:515. [PMID: 31273192 PMCID: PMC6609617 DOI: 10.1038/s41419-019-1727-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 04/23/2019] [Accepted: 05/28/2019] [Indexed: 11/09/2022]
Abstract
Spinal Muscular Atrophy (SMA) is a childhood motor neuron disease caused by mutations or deletions within the SMN1 gene. At endstages of disease there is profound loss of motor neurons, loss of axons within ventral roots and defects at the neuromuscular junctions (NMJ), as evidenced by pathological features such as pre-synaptic loss and swelling and post-synaptic shrinkage. Although these motor unit defects have been widely described, the time course and interdependancy of these aspects of motor unit degeneration are unclear. Recent reports have also revealed an early upregulation of transcripts associated with the P53 signalling pathway. The relationship between the upregulation of these transcripts and pathology within the motor unit is also unclear. In this study, we exploit the prolonged disease timecourse and defined pre-symptomatic period in the Smn2B/- mouse model to perform a temporal analysis of the different elements of motor unit pathology. We demonstrate that NMJ loss occurs prior to cell body loss, and coincides with the onset of symptoms. The onset of NMJ pathology also coincides with an increase in P53-related transcripts at the cell body. Finally, using a tamoxifen inducible P53 knockout, we demonstrate that post-natal reduction in P53 levels can reduce NMJ loss, but does not affect other aspects of NMJ pathology, motor neuron loss or the phenotype of the Smn2B/- mouse model. Together this work provides a detailed temporal description of pathology within motor units of an SMA mouse model, and demonstrates that NMJ loss is a P53-dependant process. This work supports the role for P53 as an effector of synaptic and axonal degeneration in a die-back neuropathy.
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Affiliation(s)
- Natalie L Courtney
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, Edinburgh, UK.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, Scotland, EH8 9XD, UK
| | - Alannah J Mole
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, Edinburgh, UK.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, Scotland, EH8 9XD, UK
| | - Alison K Thomson
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, Edinburgh, UK.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, Scotland, EH8 9XD, UK
| | - Lyndsay M Murray
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, Edinburgh, UK. .,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, Scotland, EH8 9XD, UK.
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13
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Zhu F, Nair RR, Fisher EMC, Cunningham TJ. Humanising the mouse genome piece by piece. Nat Commun 2019; 10:1845. [PMID: 31015419 PMCID: PMC6478830 DOI: 10.1038/s41467-019-09716-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/23/2019] [Indexed: 12/14/2022] Open
Abstract
To better understand human health and disease, researchers create a wide variety of mouse models that carry human DNA. With recent advances in genome engineering, the targeted replacement of mouse genomic regions with orthologous human sequences has become increasingly viable, ranging from finely tuned humanisation of individual nucleotides and amino acids to the incorporation of many megabases of human DNA. Here, we examine emerging technologies for targeted genomic humanisation, we review the spectrum of existing genomically humanised mouse models and the insights such models have provided, and consider the lessons learned for designing such models in the future. Generation of transgenic mice has become routine in studying gene function and disease mechanisms, but often this is not enough to fully understand human biology. Here, the authors review the current state of the art of targeted genomic humanisation strategies and their advantages over classic approaches.
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Affiliation(s)
- Fei Zhu
- Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Remya R Nair
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Elizabeth M C Fisher
- Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, WC1N 3BG, UK.
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14
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Lipnick SL, Agniel DM, Aggarwal R, Makhortova NR, Finlayson SG, Brocato A, Palmer N, Darras BT, Kohane I, Rubin LL. Systemic nature of spinal muscular atrophy revealed by studying insurance claims. PLoS One 2019; 14:e0213680. [PMID: 30870495 PMCID: PMC6417721 DOI: 10.1371/journal.pone.0213680] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/26/2019] [Indexed: 12/27/2022] Open
Abstract
Objective We investigated the presence of non-neuromuscular phenotypes in patients affected by Spinal Muscular Atrophy (SMA), a disorder caused by a mutation in the Survival of Motor Neuron (SMN) gene, and whether these phenotypes may be clinically detectable prior to clinical signs of neuromuscular degeneration and therefore independent of muscle weakness. Methods We utilized a de-identified database of insurance claims to explore the health of 1,038 SMA patients compared to controls. Two analyses were performed: (1) claims from the entire insurance coverage window; and (2) for SMA patients, claims prior to diagnosis of any neuromuscular disease or evidence of major neuromuscular degeneration to increase the chance that phenotypes could be attributed directly to reduced SMN levels. Logistic regression was used to determine whether phenotypes were diagnosed at significantly different rates between SMA patients and controls and to obtain covariate-adjusted odds ratios. Results Results from the entire coverage window revealed a broad spectrum of phenotypes that are differentially diagnosed in SMA subjects compared to controls. Moreover, data from SMA patients prior to their first clinical signs of neuromuscular degeneration revealed numerous non-neuromuscular phenotypes including defects within the cardiovascular, gastrointestinal, metabolic, reproductive, and skeletal systems. Furthermore, our data provide evidence of a potential ordering of disease progression beginning with these non-neuromuscular phenotypes. Conclusions Our data point to a direct relationship between early, detectable non-neuromuscular symptoms and SMN deficiency. Our findings are particularly important for evaluating the efficacy of SMN-increasing therapies for SMA, comparing the effectiveness of local versus systemically delivered therapeutics, and determining the optimal therapeutic treatment window prior to irreversible neuromuscular damage.
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Affiliation(s)
- Scott L. Lipnick
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
- Center for Assessment Technology & Continuous Health (CATCH), Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Denis M. Agniel
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Rahul Aggarwal
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
- Center for Assessment Technology & Continuous Health (CATCH), Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Nina R. Makhortova
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Boston Children’s Hospital, Boston, Massachusetts, United States of America
| | - Samuel G. Finlayson
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alexandra Brocato
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Nathan Palmer
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Basil T. Darras
- Boston Children’s Hospital, Boston, Massachusetts, United States of America
| | - Isaac Kohane
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lee L. Rubin
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Harvard Stem Cell Institute, Cambridge, Massachusetts, United States of America
- * E-mail:
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15
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Yin W, Rogge M. Targeting RNA: A Transformative Therapeutic Strategy. Clin Transl Sci 2019; 12:98-112. [PMID: 30706991 PMCID: PMC6440575 DOI: 10.1111/cts.12624] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 01/21/2019] [Indexed: 12/19/2022] Open
Abstract
The therapeutic pathways that modulate transcription mechanisms currently include gene knockdown and splicing modulation. However, additional mechanisms may come into play as more understanding of molecular biology and disease etiology emerge. Building on advances in chemistry and delivery technology, oligonucleotide therapeutics is emerging as an established, validated class of drugs that can modulate a multitude of genetic targets. These targets include over 10,000 proteins in the human genome that have hitherto been considered undruggable by small molecules and protein therapeutics. The approval of five oligonucleotides within the last 2 years elicited unprecedented excitement in the field. However, there are remaining challenges to overcome and significant room for future innovation to fully realize the potential of oligonucleotide therapeutics. In this review, we focus on the translational strategies encompassing preclinical evaluation and clinical development in the context of approved oligonucleotide therapeutics. Translational approaches with respect to pharmacology, pharmacokinetics, cardiac safety evaluation, and dose selection that are specific to this class of drugs are reviewed with examples. The mechanism of action, chemical evolution, and intracellular delivery of oligonucleotide therapies are only briefly reviewed to provide a general background for this class of drugs.
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MESH Headings
- Animals
- Antibodies, Monoclonal/administration & dosage
- Antibodies, Monoclonal/pharmacokinetics
- Clinical Trials as Topic
- Drug Approval
- Drug Delivery Systems/methods
- Drug Evaluation, Preclinical
- Gene Expression Regulation/drug effects
- Genetic Therapy/methods
- Humans
- Oligoribonucleotides, Antisense/administration & dosage
- Oligoribonucleotides, Antisense/genetics
- Oligoribonucleotides, Antisense/pharmacokinetics
- RNA Interference
- RNA Stability/drug effects
- RNA, Messenger/agonists
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/genetics
- RNA, Small Interfering/administration & dosage
- RNA, Small Interfering/genetics
- RNA, Small Interfering/pharmacokinetics
- Transcription, Genetic/drug effects
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Affiliation(s)
- Wei Yin
- Quantitative Clinical PharmacologyTakeda Pharmaceutical Company LtdCambridgeMassachusettsUSA
| | - Mark Rogge
- Quantitative Clinical PharmacologyTakeda Pharmaceutical Company LtdCambridgeMassachusettsUSA
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16
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Montes M, Sanford BL, Comiskey DF, Chandler DS. RNA Splicing and Disease: Animal Models to Therapies. Trends Genet 2019; 35:68-87. [PMID: 30466729 PMCID: PMC6339821 DOI: 10.1016/j.tig.2018.10.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/01/2018] [Accepted: 10/16/2018] [Indexed: 02/07/2023]
Abstract
Alternative splicing of pre-mRNA increases genetic diversity, and recent studies estimate that most human multiexon genes are alternatively spliced. If this process is not highly regulated and accurate, it leads to mis-splicing events, which may result in proteins with altered function. A growing body of work has implicated mis-splicing events in a range of diseases, including cancer, neurodegenerative diseases, and muscular dystrophies. Understanding the mechanisms that cause aberrant splicing events and how this leads to disease is vital for designing effective therapeutic strategies. In this review, we focus on advances in therapies targeting splicing, and highlight the animal models developed to recapitulate disease phenotypes as a model for testing these therapies.
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Affiliation(s)
- Matías Montes
- Molecular, Cellular, and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA; Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Brianne L Sanford
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Daniel F Comiskey
- Molecular, Cellular, and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA; Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Dawn S Chandler
- Molecular, Cellular, and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA; Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA.
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17
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Zhang Y, Long C, Bassel-Duby R, Olson EN. Myoediting: Toward Prevention of Muscular Dystrophy by Therapeutic Genome Editing. Physiol Rev 2018; 98:1205-1240. [PMID: 29717930 DOI: 10.1152/physrev.00046.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Muscular dystrophies represent a large group of genetic disorders that significantly impair quality of life and often progress to premature death. There is no effective treatment for these debilitating diseases. Most therapies, developed to date, focus on alleviating the symptoms or targeting the secondary effects, while the underlying gene mutation is still present in the human genome. The discovery and application of programmable nucleases for site-specific DNA double-stranded breaks provides a powerful tool for precise genome engineering. In particular, the CRISPR/Cas system has revolutionized the genome editing field and is providing a new path for disease treatment by targeting the disease-causing genetic mutations. In this review, we provide a historical overview of genome-editing technologies, summarize the most recent advances, and discuss potential strategies and challenges for permanently correcting genetic mutations that cause muscular dystrophies.
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Affiliation(s)
- Yu Zhang
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Chengzu Long
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Rhonda Bassel-Duby
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Eric N Olson
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
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18
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Chaytow H, Huang YT, Gillingwater TH, Faller KME. The role of survival motor neuron protein (SMN) in protein homeostasis. Cell Mol Life Sci 2018; 75:3877-3894. [PMID: 29872871 PMCID: PMC6182345 DOI: 10.1007/s00018-018-2849-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 12/11/2022]
Abstract
Ever since loss of survival motor neuron (SMN) protein was identified as the direct cause of the childhood inherited neurodegenerative disorder spinal muscular atrophy, significant efforts have been made to reveal the molecular functions of this ubiquitously expressed protein. Resulting research demonstrated that SMN plays important roles in multiple fundamental cellular homeostatic pathways, including a well-characterised role in the assembly of the spliceosome and biogenesis of ribonucleoproteins. More recent studies have shown that SMN is also involved in other housekeeping processes, including mRNA trafficking and local translation, cytoskeletal dynamics, endocytosis and autophagy. Moreover, SMN has been shown to influence mitochondria and bioenergetic pathways as well as regulate function of the ubiquitin-proteasome system. In this review, we summarise these diverse functions of SMN, confirming its key role in maintenance of the homeostatic environment of the cell.
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Affiliation(s)
- Helena Chaytow
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Yu-Ting Huang
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
| | - Kiterie M E Faller
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
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19
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Ziemka-Nalecz M, Jaworska J, Sypecka J, Zalewska T. Histone Deacetylase Inhibitors: A Therapeutic Key in Neurological Disorders? J Neuropathol Exp Neurol 2018; 77:855-870. [DOI: 10.1093/jnen/nly073] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Malgorzata Ziemka-Nalecz
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Joanna Jaworska
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Joanna Sypecka
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Teresa Zalewska
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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20
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Eshraghi M, McFall E, Gibeault S, Kothary R. Effect of genetic background on the phenotype of the Smn2B/- mouse model of spinal muscular atrophy. Hum Mol Genet 2018; 25:4494-4506. [PMID: 28172892 PMCID: PMC5409218 DOI: 10.1093/hmg/ddw278] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/03/2016] [Accepted: 08/15/2016] [Indexed: 11/14/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by mutations or deletions in the Survival Motor Neuron 1 (SMN1) gene in humans. Modifiers of the SMA symptoms have been identified and genetic background has a substantial effect in the phenotype and survival of the severe mouse model of SMA. Previously, we generated the less severe Smn2B/- mice on a mixed genetic background. To assess the phenotype of Smn deficiency on a pure genetic background, we produced Smn2B/2B congenic mice on either the C57BL/6 (BL6) or FVB strain background and characterized them at the 6th generation by breeding to Smn+/- mice. Smn2B/- mice from these crosses were evaluated for growth, survival, muscle atrophy, motor neuron loss, motor behaviour, and neuromuscular junction pathology. FVB Smn2B/- mice had a shorter life span than BL6 Smn2B/- mice (median of 19 days vs. 25 days). Similarly, all other defects assessed occurred at earlier stages in FVB Smn2B/-mice when compared to BL6 Smn2B/-mice. However, there were no differences in Smn protein levels in the spinal cords of these mice. Interestingly, levels of Plastin 3, a putative modifier of SMA, were significantly induced in spinal cords of BL6 Smn2B/- mice but not of FVB Smn2B/-mice. Our studies demonstrate that the phenotype in Smn2B/-mice is more severe in the FVB background than in the BL6 background, which could potentially be explained by the differential induction of genetic modifiers.
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Affiliation(s)
- Mehdi Eshraghi
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Emily McFall
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Sabrina Gibeault
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Rashmi Kothary
- Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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21
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O'Meara RW, Cummings SE, De Repentigny Y, McFall E, Michalski JP, Deguise MO, Gibeault S, Kothary R. Oligodendrocyte development and CNS myelination are unaffected in a mouse model of severe spinal muscular atrophy. Hum Mol Genet 2017; 26:282-292. [PMID: 28069797 DOI: 10.1093/hmg/ddw385] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 11/04/2016] [Indexed: 11/12/2022] Open
Abstract
The childhood neurodegenerative disease spinal muscular atrophy (SMA) is caused by loss-of-function mutations or deletions in the Survival Motor Neuron 1 (SMN1) gene resulting in insufficient levels of survival motor neuron (SMN) protein. Classically considered a motor neuron disease, increasing evidence now supports SMA as a multi-system disorder with phenotypes discovered in cortical neuron, astrocyte, and Schwann cell function within the nervous system. In this study, we sought to determine whether Smn was critical for oligodendrocyte (OL) development and central nervous system myelination. A mouse model of severe SMA was used to assess OL growth, migration, differentiation and myelination. All aspects of OL development and function studied were unaffected by Smn depletion. The tremendous impact of Smn depletion on a wide variety of other cell types renders the OL response unique. Further investigation of the OLs derived from SMA models may reveal disease modifiers or a compensatory mechanism allowing these cells to flourish despite the reduced levels of this multifunctional protein.
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Affiliation(s)
- Ryan W O'Meara
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Sarah E Cummings
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Yves De Repentigny
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Emily McFall
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - John-Paul Michalski
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Marc-Olivier Deguise
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Sabrina Gibeault
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Rashmi Kothary
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Centre for Neuromuscular Disease, Ottawa, Ontario, Canada.,Department of Medicine, University of Ottawa, Ottawa, ON, Canada
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22
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Howell MD, Ottesen EW, Singh NN, Anderson RL, Seo J, Sivanesan S, Whitley EM, Singh RN. TIA1 is a gender-specific disease modifier of a mild mouse model of spinal muscular atrophy. Sci Rep 2017; 7:7183. [PMID: 28775379 PMCID: PMC5543135 DOI: 10.1038/s41598-017-07468-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/26/2017] [Indexed: 02/08/2023] Open
Abstract
Spinal muscular atrophy (SMA) is caused by deletions or mutations of Survival Motor Neuron 1 (SMN1) gene. The nearly identical SMN2 cannot compensate for SMN1 loss due to exon 7 skipping. The allele C (C +/+) mouse recapitulates a mild SMA-like phenotype and offers an ideal system to monitor the role of disease-modifying factors over a long time. T-cell-restricted intracellular antigen 1 (TIA1) regulates SMN exon 7 splicing. TIA1 is reported to be downregulated in obese patients, although it is not known if the effect is gender-specific. We show that female Tia1-knockout (Tia1 -/-) mice gain significant body weight (BW) during early postnatal development. We next examined the effect of Tia1 deletion in novel C +/+/Tia1 -/- mice. Underscoring the opposing effects of Tia1 deletion and low SMN level on BW gain, both C +/+ and C +/+/Tia1 -/- females showed similar BW gain trajectory at all time points during our study. We observed early tail necrosis in C +/+/Tia1 -/- females but not in males. We show enhanced impairment of male reproductive organ development and exacerbation of the C +/+/Tia1 -/- testis transcriptome. Our findings implicate a protein factor as a gender-specific modifier of a mild mouse model of SMA.
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Affiliation(s)
- Matthew D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Rachel L Anderson
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
- Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | | | - Elizabeth M Whitley
- Department of Veterinary Pathology, Iowa State University, Ames, IA, 50011-1250, USA
- Pathogenesis, LLC, Gainesville, Florida, 32614, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA.
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23
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Singh RN, Howell MD, Ottesen EW, Singh NN. Diverse role of survival motor neuron protein. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2017; 1860:299-315. [PMID: 28095296 PMCID: PMC5325804 DOI: 10.1016/j.bbagrm.2016.12.008] [Citation(s) in RCA: 189] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 12/23/2016] [Accepted: 12/30/2016] [Indexed: 02/07/2023]
Abstract
The multifunctional Survival Motor Neuron (SMN) protein is required for the survival of all organisms of the animal kingdom. SMN impacts various aspects of RNA metabolism through the formation and/or interaction with ribonucleoprotein (RNP) complexes. SMN regulates biogenesis of small nuclear RNPs, small nucleolar RNPs, small Cajal body-associated RNPs, signal recognition particles and telomerase. SMN also plays an important role in DNA repair, transcription, pre-mRNA splicing, histone mRNA processing, translation, selenoprotein synthesis, macromolecular trafficking, stress granule formation, cell signaling and cytoskeleton maintenance. The tissue-specific requirement of SMN is dictated by the variety and the abundance of its interacting partners. Reduced expression of SMN causes spinal muscular atrophy (SMA), a leading genetic cause of infant mortality. SMA displays a broad spectrum ranging from embryonic lethality to an adult onset. Aberrant expression and/or localization of SMN has also been associated with male infertility, inclusion body myositis, amyotrophic lateral sclerosis and osteoarthritis. This review provides a summary of various SMN functions with implications to a better understanding of SMA and other pathological conditions.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
| | - Matthew D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
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24
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Therapeutic activity of modified U1 core spliceosomal particles. Nat Commun 2016; 7:11168. [PMID: 27041075 PMCID: PMC4822034 DOI: 10.1038/ncomms11168] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 02/25/2016] [Indexed: 12/15/2022] Open
Abstract
Modified U1 snRNAs bound to intronic sequences downstream of the 5′ splice site correct exon skipping caused by different types of mutations. Here we evaluate the therapeutic activity and structural requirements of these exon-specific U1 snRNA (ExSpeU1) particles. In a severe spinal muscular atrophy, mouse model, ExSpeU1, introduced by germline transgenesis, increases SMN2 exon 7 inclusion, SMN protein production and extends life span. In vitro, RNA mutant analysis and silencing experiments show that while U1A protein is dispensable, the 70K and stem loop IV elements mediate most of the splicing rescue activity through improvement of exon and intron definition. Our findings indicate that precise engineering of the U1 core spliceosomal RNA particle has therapeutic potential in pathologies associated with exon-skipping mutations. Modification of the spliceosome is being tested as a potential therapy for exon-skipping diseases, such as spinal muscular atrophy (SMA). Here the authors show that 70K and stem loop IV structural elements of a modified U1 particle are essential for splicing enhancement and effective treatment of SMA mice.
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25
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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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Ottesen EW, Howell MD, Singh NN, Seo J, Whitley EM, Singh RN. Severe impairment of male reproductive organ development in a low SMN expressing mouse model of spinal muscular atrophy. Sci Rep 2016; 6:20193. [PMID: 26830971 PMCID: PMC4735745 DOI: 10.1038/srep20193] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/23/2015] [Indexed: 12/21/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by low levels of survival motor neuron (SMN), a multifunctional protein essential for higher eukaryotes. While SMN is one of the most scrutinized proteins associated with neurodegeneration, its gender-specific role in vertebrates remains unknown. We utilized a mild SMA model (C/C model) to examine the impact of low SMN on growth and development of mammalian sex organs. We show impaired testis development, degenerated seminiferous tubules, reduced sperm count and low fertility in C/C males, but no overt sex organ phenotype in C/C females. Underscoring an increased requirement for SMN expression, wild type testis showed extremely high levels of SMN protein compared to other tissues. Our results revealed severe perturbations in pathways critical to C/C male reproductive organ development and function, including steroid biosynthesis, apoptosis, and spermatogenesis. Consistent with enhanced apoptosis in seminiferous tubules of C/C testes, we recorded a drastic increase in cells with DNA fragmentation. SMN was expressed at high levels in adult C/C testis due to an adult-specific splicing switch, but could not compensate for low levels during early testicular development. Our findings uncover novel hallmarks of SMA disease progression and link SMN to general male infertility.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
| | - Matthew D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
| | - Elizabeth M Whitley
- Department of Veterinary Pathology, Iowa State University, Ames, Iowa 50011, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
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Prior TW, Nagan N. Spinal Muscular Atrophy: Overview of Molecular Diagnostic Approaches. ACTA ACUST UNITED AC 2016; 88:9.27.1-9.27.13. [PMID: 26724723 DOI: 10.1002/0471142905.hg0927s88] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease and the most common genetic cause of infant mortality, affecting ∼1 in 10,000 live births. The disease is characterized by progressive symmetrical muscle weakness resulting from the degeneration and loss of anterior horn cells in the spinal cord and brain stem nuclei. The disease is classified on the basis of age of onset and clinical course. SMA is caused by mutations in the telomeric copy of the survival motor neuron 1 (SMN1) gene, but all patients retain a centromeric copy of the gene, SMN2. The homozygous absence of the SMN1 exon 7 has been observed in the majority of patients and is being utilized as a reliable and sensitive SMA diagnostic test. In the majority of cases, the disease severity correlates inversely with an increased SMN2 gene copy number. Carrier detection, in the deletion cases, relies on the accurate determination of the SMN1 gene copies. Since SMA is one of the most common lethal genetic disorders, with a carrier frequency of 1 in 40 to 1 in 60, direct carrier dosage testing has been beneficial to many families. This unit attempts to highlight the molecular genetics of SMA with a focus on the advantages and limitations of the current molecular technologies.
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Affiliation(s)
- Thomas W Prior
- Department of Pathology, The Ohio State University, Columbus, Ohio
| | - Narasimhan Nagan
- Integrated Genetics, Laboratory Corporation of America Holdings, Westborough, Massachusetts
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Mechanistic principles of antisense targets for the treatment of spinal muscular atrophy. Future Med Chem 2015; 7:1793-808. [PMID: 26381381 DOI: 10.4155/fmc.15.101] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a major neurodegenerative disorder of children and infants. SMA is primarily caused by low levels of SMN protein owing to deletions or mutations of the SMN1 gene. SMN2, a nearly identical copy of SMN1, fails to compensate for the loss of the production of the functional SMN protein due to predominant skipping of exon 7. Several compounds, including antisense oligonucleotides (ASOs) that elevate SMN protein from SMN2 hold the promise for treatment. An ASO-based drug currently under Phase III clinical trial employs intronic splicing silencer N1 (ISS-N1) as its target. Cumulative studies on ISS-N1 reveal a wealth of information with significance to the overall therapeutic development for SMA. Here, the authors summarize the mechanistic principles behind various antisense targets currently available for SMA therapy.
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Swiderski K, Lynch GS. Therapeutic potential of orphan drugs for the rare skeletal muscle diseases. Expert Opin Orphan Drugs 2015. [DOI: 10.1517/21678707.2015.1085858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Wertz MH, Sahin M. Developing therapies for spinal muscular atrophy. Ann N Y Acad Sci 2015; 1366:5-19. [PMID: 26173388 DOI: 10.1111/nyas.12813] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 05/05/2015] [Accepted: 05/18/2015] [Indexed: 12/17/2022]
Abstract
Spinal muscular atrophy is an autosomal-recessive pediatric neurodegenerative disease characterized by loss of spinal motor neurons. It is caused by mutation in the gene survival of motor neuron 1 (SMN1), leading to loss of function of the full-length SMN protein. SMN has a number of functions in neurons, including RNA splicing and snRNP biogenesis in the nucleus, and RNA trafficking in neurites. The expression level of full-length SMN protein from the SMN2 locus modifies disease severity. Increasing full-length SMN protein by a small amount can lead to significant improvements in the neurological phenotype. Currently available interventions for spinal muscular atrophy patients are physical therapy and orthopedic, nutritional, and pulmonary interventions; these are palliative or supportive measures and do not address the etiology of the disease. In the past decade, there has been a push for developing therapeutics to improve motor phenotypes and increase life span of spinal muscular atrophy patients. These therapies are aimed primarily at restoration of full-length SMN protein levels, but other neuroprotective treatments have been investigated as well. Here, we discuss recent advances in basic and clinical studies toward finding safe and effective treatments of spinal muscular atrophy using gene therapy, antisense oligonucleotides, and other small molecule modulators of SMN expression.
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Affiliation(s)
- Mary H Wertz
- The F.M. Kirby Neurobiology Center, Department of Neurology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts
| | - Mustafa Sahin
- The F.M. Kirby Neurobiology Center, Department of Neurology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts
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31
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Genetically modified pigs to model human diseases. J Appl Genet 2015; 55:53-64. [PMID: 24234401 DOI: 10.1007/s13353-013-0182-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 10/22/2013] [Indexed: 01/06/2023]
Abstract
Genetically modified mice are powerful tools to investigate the molecular basis of many human diseases. Mice are, however, of limited value for preclinical studies, because they differ significantly from humans in size, general physiology, anatomy and lifespan. Considerable efforts are, thus, being made to develop alternative animal models for a range of human diseases. These promise powerful new resources that will aid the development of new diagnostics, medicines and medical procedures. Here, we provide a comprehensive review of genetically modified porcine models described in the scientific literature: various cancers, cystic fibrosis, Duchenne muscular dystrophy, autosomal polycystic kidney disease, Huntington’s disease, spinal muscular atrophy, haemophilia A, X-linked severe combined immunodeficiency, retinitis pigmentosa, Stargardt disease, Alzheimer’s disease, various forms of diabetes mellitus and cardiovascular diseases.
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Singh NN, Lee BM, Singh RN. Splicing regulation in spinal muscular atrophy by an RNA structure formed by long-distance interactions. Ann N Y Acad Sci 2015; 1341:176-87. [PMID: 25727246 PMCID: PMC4651915 DOI: 10.1111/nyas.12727] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Humans carry two copies of the survival motor neuron gene: SMN1 and SMN2. Loss of SMN1 coupled with skipping of SMN2 exon 7 causes spinal muscular atrophy (SMA), a leading genetic disease associated with infant mortality. Our discovery of intronic splicing silencer N1 (ISS-N1) is a promising target, currently in a phase III clinical trial, for an antisense oligonucleotide-mediated splicing correction in SMA. We have recently shown that the first residue of ISS-N1 is locked in a unique RNA structure that we term ISTL1 (internal stem through long-distance interaction-1). Complementary strands of ISTL1 are separated from each other by 279 nucleotides. Using site-specific mutations and chemical structure probing, we confirmed the formation and functional significance of ISTL1. Located in the middle of intron 7, the 3' strand of ISTL1 falls within an inhibitory region that we term ISS-N2. We demonstrate that an antisense oligonucleotide-mediated sequestration of ISS-N2 fully corrects SMN2 exon 7 splicing and restores high levels of SMN in SMA patient cells. These results underscore the therapeutic potential of the regulatory information present in a secondary and high-order RNA structure of a human intron.
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Affiliation(s)
- Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa
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Coque E, Raoul C, Bowerman M. ROCK inhibition as a therapy for spinal muscular atrophy: understanding the repercussions on multiple cellular targets. Front Neurosci 2014; 8:271. [PMID: 25221469 PMCID: PMC4148024 DOI: 10.3389/fnins.2014.00271] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/11/2014] [Indexed: 12/28/2022] Open
Abstract
Spinal muscular atrophy (SMA) is the most common genetic disease causing infant death, due to an extended loss of motoneurons. This neuromuscular disorder results from deletions and/or mutations within the Survival Motor Neuron 1 (SMN1) gene, leading to a pathological decreased expression of functional full-length SMN protein. Emerging studies suggest that the small GTPase RhoA and its major downstream effector Rho kinase (ROCK), which both play an instrumental role in cytoskeleton organization, contribute to the pathology of motoneuron diseases. Indeed, an enhanced activation of RhoA and ROCK has been reported in the spinal cord of an SMA mouse model. Moreover, the treatment of SMA mice with ROCK inhibitors leads to an increased lifespan as well as improved skeletal muscle and neuromuscular junction pathology, without preventing motoneuron degeneration. Although motoneurons are the primary target in SMA, an increasing number of reports show that other cell types inside and outside the central nervous system contribute to SMA pathogenesis. As administration of ROCK inhibitors to SMA mice was systemic, the improvement in survival and phenotype could therefore be attributed to specific effects on motoneurons and/or on other non-neuronal cell types. In the present review, we will present the various roles of the RhoA/ROCK pathway in several SMA cellular targets including neurons, myoblasts, glial cells, cardiomyocytes and pancreatic cells as well as discuss how ROCK inhibition may ameliorate their health and function. It is most likely a concerted influence of ROCK modulation on all these cell types that ultimately lead to the observed benefits of pharmacological ROCK inhibition in SMA mice.
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Affiliation(s)
- Emmanuelle Coque
- The Institute for Neurosciences of Montpellier, Saint Eloi Hospital, Institut National de la Santé et de la Recherche Médicale UMR1051 Montpellier, France ; Université de Montpellier 1 and 2 Montpellier, France
| | - Cédric Raoul
- The Institute for Neurosciences of Montpellier, Saint Eloi Hospital, Institut National de la Santé et de la Recherche Médicale UMR1051 Montpellier, France ; Université de Montpellier 1 and 2 Montpellier, France
| | - Mélissa Bowerman
- The Institute for Neurosciences of Montpellier, Saint Eloi Hospital, Institut National de la Santé et de la Recherche Médicale UMR1051 Montpellier, France ; Université de Montpellier 1 and 2 Montpellier, France
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Kissel JT, Elsheikh B, King WM, Freimer M, Scott CB, Kolb SJ, Reyna SP, Crawford TO, Simard LR, Krosschell KJ, Acsadi G, Schroth MK, D'Anjou G, LaSalle B, Prior TW, Sorenson S, Maczulski JA, Swoboda KJ. SMA valiant trial: a prospective, double-blind, placebo-controlled trial of valproic acid in ambulatory adults with spinal muscular atrophy. Muscle Nerve 2014; 49:187-92. [PMID: 23681940 DOI: 10.1002/mus.23904] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2013] [Indexed: 12/15/2022]
Abstract
INTRODUCTION An open-label trial suggested that valproic acid (VPA) improved strength in adults with spinal muscular atrophy (SMA). We report a 12-month, double-blind, cross-over study of VPA in ambulatory SMA adults. METHODS There were 33 subjects, aged 20–55 years, included in this investigation. After baseline assessment, subjects were randomized to receive VPA (10–20 mg/kg/day) or placebo. At 6 months, patients were switched to the other group. Assessments were performed at 3, 6, and 12 months. The primary outcome was the 6-month change in maximum voluntary isometric contraction testing with pulmonary, electrophysiological, and functional secondary outcomes. RESULTS Thirty subjects completed the study. VPA was well tolerated, and compliance was good. There was no change in primary or secondary outcomes at 6 or 12 months. CONCLUSIONS VPA did not improve strength or function in SMA adults. The outcomes used are feasible and reliable and can be employed in future trials in SMA adults.
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Mulcahy PJ, Iremonger K, Karyka E, Herranz-Martín S, Shum KT, Tam JKV, Azzouz M. Gene therapy: a promising approach to treating spinal muscular atrophy. Hum Gene Ther 2014; 25:575-86. [PMID: 24845847 DOI: 10.1089/hum.2013.186] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a severe autosomal recessive disease caused by a genetic defect in the survival motor neuron 1 (SMN1) gene, which encodes SMN, a protein widely expressed in all eukaryotic cells. Depletion of the SMN protein causes muscle weakness and progressive loss of movement in SMA patients. The field of gene therapy has made major advances over the past decade, and gene delivery to the central nervous system (CNS) by in vivo or ex vivo techniques is a rapidly emerging field in neuroscience. Despite Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis being among the most common neurodegenerative diseases in humans and attractive targets for treatment development, their multifactorial origin and complicated genetics make them less amenable to gene therapy. Monogenic disorders resulting from modifications in a single gene, such as SMA, prove more favorable and have been at the fore of this evolution of potential gene therapies, and results to date have been promising at least. With the estimated number of monogenic diseases standing in the thousands, elucidating a therapeutic target for one could have major implications for many more. Recent progress has brought about the commercialization of the first gene therapies for diseases, such as pancreatitis in the form of Glybera, with the potential for other monogenic disease therapies to follow suit. While much research has been carried out, there are many limiting factors that can halt or impede translation of therapies from the bench to the clinic. This review will look at both recent advances and encountered impediments in terms of SMA and endeavor to highlight the promising results that may be applicable to various associated diseases and also discuss the potential to overcome present limitations.
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Affiliation(s)
- Pádraig J Mulcahy
- 1 Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield , Sheffield S10 2HQ, United Kingdom
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Kang PB, Gooch CL, McDermott MP, Darras BT, Finkel RS, Yang ML, Sproule DM, Chung WK, Kaufmann P, de Vivo DC. The motor neuron response to SMN1 deficiency in spinal muscular atrophy. Muscle Nerve 2014; 49:636-44. [PMID: 23893312 DOI: 10.1002/mus.23967] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/09/2013] [Accepted: 07/12/2013] [Indexed: 12/23/2022]
Abstract
INTRODUCTION The purpose of this study was to measure and analyze motor unit number estimation (MUNE) values longitudinally in spinal muscular atrophy (SMA). METHODS Sixty-two children with SMA types 2 and 3 were observed prospectively for up to 42 months. Longitudinal electrophysiological data were collected, including compound motor action potential (CMAP), single motor unit action potential (SMUP), and MUNE. RESULTS Significant motor neuron loss and compensatory collateral reinnervation were noted at baseline. Over time, there was a significant mean increase in MUNE (4.92 units/year, P = 0.009), a mean decrease in SMUP amplitude (-6.32 μV/year, P = 0.10), and stable CMAP amplitude. CONCLUSIONS The unexpected longitudinal results differ from findings in amyotrophic lateral sclerosis studies, perhaps indicating that compensatory processes in SMA involve new motor unit development. A better understanding of the mechanisms of motor unit decline and compensation in SMA is important for assessing novel therapeutic strategies and for providing key insights into disease pathophysiology.
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Affiliation(s)
- Peter B Kang
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts, 02115, USA
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Rigo F, Chun SJ, Norris DA, Hung G, Lee S, Matson J, Fey RA, Gaus H, Hua Y, Grundy JS, Krainer AR, Henry SP, Bennett CF. Pharmacology of a central nervous system delivered 2'-O-methoxyethyl-modified survival of motor neuron splicing oligonucleotide in mice and nonhuman primates. J Pharmacol Exp Ther 2014; 350:46-55. [PMID: 24784568 DOI: 10.1124/jpet.113.212407] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a debilitating neuromuscular disease caused by the loss of survival of motor neuron (SMN) protein. Previously, we demonstrated that ISIS 396443, an antisense oligonucleotide (ASO) targeted to the SMN2 pre-mRNA, is a potent inducer of SMN2 exon 7 inclusion and SMN protein expression, and improves function and survival of mild and severe SMA mouse models. Here, we demonstrate that ISIS 396443 is the most potent ASO in central nervous system (CNS) tissues of adult mice, compared with several other chemically modified ASOs. We evaluated methods of ISIS 396443 delivery to the CNS and characterized its pharmacokinetics and pharmacodynamics in rodents and nonhuman primates (NHPs). Intracerebroventricular bolus injection is a more efficient method of delivering ISIS 396443 to the CNS of rodents, compared with i.c.v. infusion. For both methods of delivery, the duration of ISIS 396443-mediated SMN2 splicing correction is long lasting, with maximal effects still observed 6 months after treatment discontinuation. Administration of ISIS 396443 to the CNS of NHPs by a single intrathecal bolus injection results in widespread distribution throughout the spinal cord. Based upon these preclinical studies, we have advanced ISIS 396443 into clinical development.
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Affiliation(s)
- Frank Rigo
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Seung J Chun
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Daniel A Norris
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Gene Hung
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Sam Lee
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - John Matson
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Robert A Fey
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Hans Gaus
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Yimin Hua
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - John S Grundy
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Adrian R Krainer
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - Scott P Henry
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
| | - C Frank Bennett
- Isis Pharmaceuticals, Carlsbad, California (F.R., S.J.C., D.A.N., G.H., S.L., J.M., R.A.F., H.G., J.S.G., S.P.H., C.F.B.); and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (Y.H., A.R.K.)
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Passini MA, Bu J, Richards AM, Treleaven CM, Sullivan JA, O'Riordan CR, Scaria A, Kells AP, Samaranch L, San Sebastian W, Federici T, Fiandaca MS, Boulis NM, Bankiewicz KS, Shihabuddin LS, Cheng SH. Translational fidelity of intrathecal delivery of self-complementary AAV9-survival motor neuron 1 for spinal muscular atrophy. Hum Gene Ther 2014; 25:619-30. [PMID: 24617515 DOI: 10.1089/hum.2014.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disease caused by mutations in survival motor neuron 1 (SMN1). Previously, we showed that central nervous system (CNS) delivery of an adeno-associated viral (AAV) vector encoding SMN1 produced significant improvements in survival in a mouse model of SMA. Here, we performed a dose-response study in SMA mice to determine the levels of SMN in the spinal cord necessary for efficacy, and measured the efficiency of motor neuron transduction in the spinal cord after intrathecal delivery in pigs and nonhuman primates (NHPs). CNS injections of 5e10, 1e10, and 1e9 genome copies (gc) of self-complementary AAV9 (scAAV9)-hSMN1 into SMA mice extended their survival from 17 to 153, 70, and 18 days, respectively. Spinal cords treated with 5e10, 1e10, and 1e9 gc showed that 70-170%, 30-100%, and 10-20% of wild-type levels of SMN were attained, respectively. Furthermore, detectable SMN expression in a minimum of 30% motor neurons correlated with efficacy. A comprehensive analysis showed that intrathecal delivery of 2.5e13 gc of scAAV9-GFP transduced 25-75% of the spinal cord motor neurons in NHPs. Thus, the extent of gene expression in motor neurons necessary to confer efficacy in SMA mice could be obtained in large-animal models, justifying the continual development of gene therapy for SMA.
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Affiliation(s)
- Marco A Passini
- 1 Rare Diseases Science, Genzyme, a Sanofi Company , Framingham, MA 01701
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Babin PJ, Goizet C, Raldúa D. Zebrafish models of human motor neuron diseases: advantages and limitations. Prog Neurobiol 2014; 118:36-58. [PMID: 24705136 DOI: 10.1016/j.pneurobio.2014.03.001] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/11/2014] [Accepted: 03/14/2014] [Indexed: 01/08/2023]
Abstract
Motor neuron diseases (MNDs) are an etiologically heterogeneous group of disorders of neurodegenerative origin, which result in degeneration of lower (LMNs) and/or upper motor neurons (UMNs). Neurodegenerative MNDs include pure hereditary spastic paraplegia (HSP), which involves specific degeneration of UMNs, leading to progressive spasticity of the lower limbs. In contrast, spinal muscular atrophy (SMA) involves the specific degeneration of LMNs, with symmetrical muscle weakness and atrophy. Amyotrophic lateral sclerosis (ALS), the most common adult-onset MND, is characterized by the degeneration of both UMNs and LMNs, leading to progressive muscle weakness, atrophy, and spasticity. A review of the comparative neuroanatomy of the human and zebrafish motor systems showed that, while the zebrafish was a homologous model for LMN disorders, such as SMA, it was only partially relevant in the case of UMN disorders, due to the absence of corticospinal and rubrospinal tracts in its central nervous system. Even considering the limitation of this model to fully reproduce the human UMN disorders, zebrafish offer an excellent alternative vertebrate model for the molecular and genetic dissection of MND mechanisms. Its advantages include the conservation of genome and physiological processes and applicable in vivo tools, including easy imaging, loss or gain of function methods, behavioral tests to examine changes in motor activity, and the ease of simultaneous chemical/drug testing on large numbers of animals. This facilitates the assessment of the environmental origin of MNDs, alone or in combination with genetic traits and putative modifier genes. Positive hits obtained by phenotype-based small-molecule screening using zebrafish may potentially be effective drugs for treatment of human MNDs.
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Affiliation(s)
- Patrick J Babin
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France.
| | - Cyril Goizet
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France; CHU Bordeaux, Hôpital Pellegrin, Service de Génétique Médicale, Bordeaux, France
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Schmitt F, Hussain G, Dupuis L, Loeffler JP, Henriques A. A plural role for lipids in motor neuron diseases: energy, signaling and structure. Front Cell Neurosci 2014; 8:25. [PMID: 24600344 PMCID: PMC3929843 DOI: 10.3389/fncel.2014.00025] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 01/17/2013] [Indexed: 12/12/2022] Open
Abstract
Motor neuron diseases (MNDs) are characterized by selective death of motor neurons and include mainly adult-onset amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). Neurodegeneration is not the single pathogenic event occurring during disease progression. There are multiple lines of evidence for the existence of defects in lipid metabolism at peripheral level. For instance, hypermetabolism is well characterized in ALS, and dyslipidemia correlates with better prognosis in patients. Lipid metabolism plays also a role in other MNDs. In SMA, misuse of lipids as energetic nutrients is described in patients and in related animal models. The composition of structural lipids in the central nervous system is modified, with repercussion on membrane fluidity and on cell signaling mediated by bioactive lipids. Here, we review the main epidemiologic and mechanistic findings that link alterations of lipid metabolism and motor neuron degeneration, and we discuss the rationale of targeting these modifications for therapeutic management of MNDs.
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Affiliation(s)
- Florent Schmitt
- Mécanismes Centraux et Périphériques de la Neurodégénerescence, INSERM U1118 Strasbourg, France ; UMRS1118, Fédération de Médecine Translationnelle de Strasbourg Université de Strasbourg, France
| | - Ghulam Hussain
- Mécanismes Centraux et Périphériques de la Neurodégénerescence, INSERM U1118 Strasbourg, France ; UMRS1118, Fédération de Médecine Translationnelle de Strasbourg Université de Strasbourg, France
| | - Luc Dupuis
- Mécanismes Centraux et Périphériques de la Neurodégénerescence, INSERM U1118 Strasbourg, France ; UMRS1118, Fédération de Médecine Translationnelle de Strasbourg Université de Strasbourg, France
| | - Jean-Philippe Loeffler
- Mécanismes Centraux et Périphériques de la Neurodégénerescence, INSERM U1118 Strasbourg, France ; UMRS1118, Fédération de Médecine Translationnelle de Strasbourg Université de Strasbourg, France
| | - Alexandre Henriques
- Mécanismes Centraux et Périphériques de la Neurodégénerescence, INSERM U1118 Strasbourg, France ; UMRS1118, Fédération de Médecine Translationnelle de Strasbourg Université de Strasbourg, France
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Seo J, Howell MD, Singh NN, Singh RN. Spinal muscular atrophy: an update on therapeutic progress. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2180-90. [PMID: 23994186 DOI: 10.1016/j.bbadis.2013.08.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/27/2013] [Accepted: 08/14/2013] [Indexed: 12/24/2022]
Abstract
Humans have two nearly identical copies of survival motor neuron gene: SMN1 and SMN2. Deletion or mutation of SMN1 combined with the inability of SMN2 to compensate for the loss of SMN1 results in spinal muscular atrophy (SMA), a leading genetic cause of infant mortality. SMA affects 1 in ~6000 live births, a frequency much higher than in several genetic diseases. The major known defect of SMN2 is the predominant exon 7 skipping that leads to production of a truncated protein (SMNΔ7), which is unstable. Therefore, SMA has emerged as a model genetic disorder in which almost the entire disease population could be linked to the aberrant splicing of a single exon (i.e. SMN2 exon 7). Diverse treatment strategies aimed at improving the function of SMN2 have been envisioned. These strategies include, but are not limited to, manipulation of transcription, correction of aberrant splicing and stabilization of mRNA, SMN and SMNΔ7. This review summarizes up to date progress and promise of various in vivo studies reported for the treatment of SMA.
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Affiliation(s)
- Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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McGivern JV, Patitucci TN, Nord JA, Barabas MEA, Stucky CL, Ebert AD. Spinal muscular atrophy astrocytes exhibit abnormal calcium regulation and reduced growth factor production. Glia 2013; 61:1418-1428. [PMID: 23839956 DOI: 10.1002/glia.22522] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Revised: 04/01/2013] [Accepted: 04/23/2013] [Indexed: 02/06/2023]
Abstract
Spinal muscular atrophy (SMA) is a genetic disorder caused by the deletion of the survival motor neuron 1 (SMN1) gene that leads to loss of motor neurons in the spinal cord. Although motor neurons are selectively lost during SMA pathology, selective replacement of SMN in motor neurons does not lead to full rescue in mouse models. Due to the ubiquitous expression of SMN, it is likely that other cell types besides motor neurons are affected by its disruption and therefore may contribute to disease pathology. Here we show that astrocytes in SMAΔ7 mouse spinal cord and from SMA-induced pluripotent stem cells exhibit morphological and cellular changes indicative of activation before overt motor neuron loss. Furthermore, our in vitro studies show mis-regulation of basal calcium and decreased response to adenosine triphosphate stimulation indicating abnormal astrocyte function. Together, for the first time, these data show early disruptions in astrocytes that may contribute to SMA disease pathology.
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Affiliation(s)
- Jered V McGivern
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin. 8701 Watertown Plank Rd, Milwaukee, WI 53226
| | - Teresa N Patitucci
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin. 8701 Watertown Plank Rd, Milwaukee, WI 53226
| | - Joshua A Nord
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin. 8701 Watertown Plank Rd, Milwaukee, WI 53226
| | - Marie-Elizabeth A Barabas
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin. 8701 Watertown Plank Rd, Milwaukee, WI 53226
| | - Cheryl L Stucky
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin. 8701 Watertown Plank Rd, Milwaukee, WI 53226
| | - Allison D Ebert
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin. 8701 Watertown Plank Rd, Milwaukee, WI 53226
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Sivanesan S, Howell MD, DiDonato CJ, Singh RN. Antisense oligonucleotide mediated therapy of spinal muscular atrophy. Transl Neurosci 2013; 4:10.2478/s13380-013-0109-2. [PMID: 24265944 PMCID: PMC3832262 DOI: 10.2478/s13380-013-0109-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Spinal muscular atrophy (SMA) is the leading genetic cause of infant mortality. SMA results from deletions or mutations of survival motor neuron 1 (SMN1), an essential gene. SMN2, a nearly identical copy, can compensate for SMN1 loss if SMN2 exon 7 skipping is prevented. Among the many cis-elements involved in the splicing regulation of SMN exon 7, intronic splicing silencer N1 (ISS-N1) has emerged as the most effective target for an antisense oligonucleotide (ASO)-mediated splicing correction of SMN2 exon 7. Blocking of ISS-N1 by an ASO has been shown to fully restore SMN2 exon 7 inclusion in SMA patient cells as well as in vivo. Here we review how ISS-N1 targeting ASOs that use different chemistries respond differently in the various SMA mouse models. We also compare other ASO-based strategies for therapeutic splicing correction in SMA. Given that substantial progress on ASO-based strategies to promote SMN2 exon 7 inclusion in SMA has been made, and that similar approaches in a growing number of genetic diseases are possible, this report has wide implications.
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Affiliation(s)
- Senthilkumar Sivanesan
- Department of Biomedical Sciences, College of Veterinary Medicine (2034 Vet Med Bld.), Iowa State University, Ames, IA 50011
| | - Matthew D. Howell
- Department of Biomedical Sciences, College of Veterinary Medicine (2034 Vet Med Bld.), Iowa State University, Ames, IA 50011
| | - Christine J. DiDonato
- Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
- Human Molecular Genetics Program, Ann & Robert H. Lurie Children’s Hospital of Chicago, Research Center, Chicago, IL 60614
| | - Ravindra N. Singh
- Department of Biomedical Sciences, College of Veterinary Medicine (2034 Vet Med Bld.), Iowa State University, Ames, IA 50011
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Cobb MS, Rose FF, Rindt H, Glascock JJ, Shababi M, Miller MR, Osman EY, Yen PF, Garcia ML, Martin BR, Wetz MJ, Mazzasette C, Feng Z, Ko CP, Lorson CL. Development and characterization of an SMN2-based intermediate mouse model of Spinal Muscular Atrophy. Hum Mol Genet 2013; 22:1843-55. [PMID: 23390132 DOI: 10.1093/hmg/ddt037] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is due to the loss of the survival motor neuron gene 1 (SMN1), resulting in motor neuron (MN) degeneration, muscle atrophy and loss of motor function. While SMN2 encodes a protein identical to SMN1, a single nucleotide difference in exon 7 causes most of the SMN2-derived transcripts to be alternatively spliced resulting in a truncated and unstable protein (SMNΔ7). SMA patients retain at least one SMN2 copy, making it an important target for therapeutics. Many of the existing SMA models are very severe, with animals typically living less than 2 weeks. Here, we present a novel intermediate mouse model of SMA based upon the human genomic SMN2 gene. Genetically, this model is similar to the well-characterized SMNΔ7 model; however, we have manipulated the SMNΔ7 transgene to encode a modestly more functional protein referred to as SMN read-through (SMN(RT)). By introducing the SMN(RT) transgene onto the background of a severe mouse model of SMA (SMN2(+/+);Smn(-/-)), disease severity was significantly decreased based upon a battery of phenotypic parameters, including MN pathology and a significant extension in survival. Importantly, there is not a full phenotypic correction, allowing for the examination of a broad range of therapeutics, including SMN2-dependent and SMN-independent pathways. This novel animal model serves as an important biological and therapeutic model for less severe forms of SMA and provides an in vivo validation of the SMN(RT) protein.
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Affiliation(s)
- Melissa S Cobb
- Department of Veterinary Pathobiology, Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
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