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Polverini E, Squeri P, Gherardi V. Effect of E134K pathogenic mutation of SMN protein on SMN-SmD1 interaction, with implication in spinal muscular atrophy: A molecular dynamics study. Int J Biol Macromol 2024; 275:133663. [PMID: 38969036 DOI: 10.1016/j.ijbiomac.2024.133663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 07/07/2024]
Abstract
Spinal muscular atrophy (SMA) is a disease that results from mutations in the Survival of Motor Neuron (SMN) gene 1, leading to muscle atrophy due to motor neurons degeneration. SMN plays a crucial role in the assembly of spliceosomal small nuclear ribonucleoprotein complexes via binding to the arginine-glycine rich C-terminal tails of Sm proteins recognized by SMN Tudor domain. E134K Tudor mutation, cause of the more severe type I SMA, compromises the SMN-Sm interaction without a perturbation of the domain fold. By molecular dynamics simulations, we investigated the mechanism of Tudor-SmD1 interaction, and the effects on it of E134K mutation. It was observed that E134 is crucial to catch the positive dimethylated arginines (DMRs) of the SmD1 tail that, wrapping around the acidic Tudor surface, enters a central DMR into an aromatic cage. The flexible cage residue Y130 must be blocked from the wrapped tail to assure a stable binding. The charge inversion in E134K mutation causes the loss of a critical anchor point, disfavoring the tail wrapping and leaving Y130 free to swing, leading to DMR detachments and exposition of the C-terminal region of the tail. This could suggest new hypotheses regarding a possible autoimmune response by anti-Sm autoantibodies.
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Affiliation(s)
- Eugenia Polverini
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parco Area delle Scienze 7/A, 43124 Parma, Italy.
| | - Pietro Squeri
- Department of Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Valeria Gherardi
- Department of Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
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2
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Cook SL, Stout C, Kirkeby L, Vidal-Folch N, Oglesbee D, Hasadsri L, Selcen D, Milone M, Anderson D, Staff NP. SMN1 c.5C>G (p.Ala2Gly) missense variant, a challenging molecular SMA diagnosis associated with mild disease, preserves SMN nuclear gems in patient-specific fibroblasts. Front Genet 2024; 15:1406819. [PMID: 39139818 PMCID: PMC11319185 DOI: 10.3389/fgene.2024.1406819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 06/25/2024] [Indexed: 08/15/2024] Open
Abstract
Introduction Spinal muscular atrophy (SMA) is caused by homozygous loss of the SMN1 gene with SMN2 gene copy number correlating with disease severity. Rarely SMA is caused by a deletion on one allele and a pathogenic variant on the other. The pathogenic missense variant c.5C>G (p.Ala2Gly) correlates with a mild disease phenotype that does not correlate with SMN2 copy number. In a mouse model the c.5C>G transgene produces SMN that is thought to form partially functional SMN complexes, but levels in humans have not yet been investigated. Methods We identified two patients with mild SMA caused by a heterozygous deletion of SMN1 and the heterozygous variant, c.5C>G. Molecular findings were confirmed with deletion/duplication analysis and Sanger sequencing. Skin fibroblasts were collected and cultured, and SMN expression was analyzed using immunofluorescence. Results Two patients with slowly progressing mild weakness were confirmed to have heterozygous pathogenic missense variant c.5C>G and a heterozygous deletion of SMN1. Their clinical presentation revealed much milder disease progression than patients with matched SMN2 copy number. Analysis of the patients' fibroblasts revealed much higher numbers of SMN nuclear complexes than a patient with a homozygous SMN1 deletion and matched SMN2 copy number. Conclusions These case reports reinforce that the rare c.5C>G variant causes mild disease. Furthermore, the analysis of SMA nuclear gems in patient samples supports the theory that the p.Ala2Gly SMN can form partially functional SMN complexes that may carry out essential cellular functions and result in mild disease.
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Affiliation(s)
- Sara L. Cook
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Christian Stout
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Lindsey Kirkeby
- Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, United States
| | - Noemi Vidal-Folch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Devin Oglesbee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Linda Hasadsri
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
| | | | - Daniel Anderson
- Department of Neurology, Mayo Clinic Health System, La Crosse, WI, United States
| | - Nathan P. Staff
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
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3
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Mendonça RH, Ortega AB, Matsui C, van der Linden V, Kerstenetzky M, Grossklauss LF, Silveira-Lucas EL, Polido GJ, Zanoteli E. Gene replacement therapy for spinal muscular atrophy: safety and preliminary efficacy in a Brazilian cohort. Gene Ther 2024; 31:391-399. [PMID: 38839888 DOI: 10.1038/s41434-024-00456-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/30/2024] [Accepted: 05/09/2024] [Indexed: 06/07/2024]
Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease associated with progressive muscle weakness, ventilatory failure, and reduced survival. Onasemnogene abeparvovec is the first gene replacement therapy (GT) approved to treat this condition. An observational retrospective study was conducted to assess adverse events and efficacy of GT in SMA patients. Forty-one patients with SMA (58.5% females and 80.1% SMA type 1) were included. The mean age at GT dosing was 18 (±6.4) months. Thirty-six patients (87.8%) were under previous treatment with nusinersen, and 10 (24.4%) continued nusinersen after GT. Mean CHOP-INTEND increased 13 points after 6 months and this finding did not differ between groups according to nusinersen maintenance after GT (p = 0.949). Among SMA type 1 patients, 14 (46.6%) reached the ability to sit alone. Liver transaminases elevation at least two times higher than the upper limit of normal value occurred in 29 (70.7%) patients. Thrombocytopenia occurred in 13 (31.7%) patients, and one presented thrombotic microangiopathy. Older age (>2 years) was associated with more prolonged use of corticosteroids (p = 0.021). GT is effective in SMA patients, combined nusinersen after GT did not appear to add gain in motor function and older age is associated with prolonged corticosteroid use.
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Affiliation(s)
- Rodrigo Holanda Mendonça
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil.
- Hospital Samaritano Higienópolis, São Paulo, Brazil.
| | | | - Ciro Matsui
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
- Hospital Samaritano Higienópolis, São Paulo, Brazil
| | | | | | | | | | - Graziela Jorge Polido
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
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4
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Ersöz E, Demir-Dora D. Unveiling the potential of antisense oligonucleotides: Mechanisms, therapies, and safety insights. Drug Dev Res 2024; 85:e22187. [PMID: 38764172 DOI: 10.1002/ddr.22187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/01/2024] [Accepted: 04/07/2024] [Indexed: 05/21/2024]
Abstract
Antisense oligonucleotides (ASOs) are short, synthetic, single-stranded deoxynucleotide sequences composed of phosphate backbone-connected sugar rings. Designing of those strands is based on Watson-Crick hydrogen bonding mechanism. Thanks to rapidly advancing medicine and technology, evolving of the gene therapy area and ASO approaches gain attention. Considering the genetic basis of diseases, it is promising that gene therapy approaches offer more specific and effective options compared to conventional treatments. The objective of this review is to explain the mechanism of ASOs and discuss the characteristics and safety profiles of therapeutic agents in this field. Pharmacovigilance for gene therapy products is complex, requiring accurate assessment of benefit-risk balance and evaluation of adverse effects.
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Affiliation(s)
- Edanur Ersöz
- Health Sciences Institute, Department of Gene and Cell Therapy, Akdeniz University, Antalya, Turkey
| | - Devrim Demir-Dora
- Health Sciences Institute, Department of Gene and Cell Therapy, Akdeniz University, Antalya, Turkey
- Faculty of Medicine, Department of Medical Pharmacology, Akdeniz University, Antalya, Turkey
- Health Sciences Institute, Department of Medical Biotechnology, Akdeniz University, Antalya, Turkey
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5
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Grätz C, Schuster M, Brandes F, Meidert AS, Kirchner B, Reithmair M, Schelling G, Pfaffl MW. A pipeline for the development and analysis of extracellular vesicle-based transcriptomic biomarkers in molecular diagnostics. Mol Aspects Med 2024; 97:101269. [PMID: 38552453 DOI: 10.1016/j.mam.2024.101269] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 03/11/2024] [Accepted: 03/17/2024] [Indexed: 06/12/2024]
Abstract
Extracellular vesicles are shed by every cell type and can be found in any biofluid. They contain different molecules that can be utilized as biomarkers, including several RNA species which they protect from degradation. Here, we present a pipeline for the development and analysis of extracellular vesicle-associated transcriptomic biomarkers that our group has successfully applied multiple times. We highlight the key steps of the pipeline and give particular emphasis to the necessary quality control checkpoints, which are linked to numerous available guidelines that should be considered along the workflow. Our pipeline starts with patient recruitment and continues with blood sampling and processing. The purification and characterization of extracellular vesicles is explained in detail, as well as the isolation and quality control of extracellular vesicle-associated RNA. We point out the possible pitfalls during library preparation and RNA sequencing and present multiple bioinformatic tools to pinpoint biomarker signature candidates from the sequencing data. Finally, considerations and pitfalls during the validation of the biomarker signature using RT-qPCR will be elaborated.
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Affiliation(s)
- Christian Grätz
- Department of Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Freising, Germany.
| | - Martina Schuster
- Institute of Human Genetics, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Florian Brandes
- Department of Anesthesiology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Agnes S Meidert
- Department of Anesthesiology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Benedikt Kirchner
- Department of Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Freising, Germany; Institute of Human Genetics, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Marlene Reithmair
- Institute of Human Genetics, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Gustav Schelling
- Department of Anesthesiology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Michael W Pfaffl
- Department of Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Freising, Germany.
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6
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Holm LL, Doktor TK, Flugt KK, Petersen US, Petersen R, Andresen B. All exons are not created equal-exon vulnerability determines the effect of exonic mutations on splicing. Nucleic Acids Res 2024; 52:4588-4603. [PMID: 38324470 PMCID: PMC11077056 DOI: 10.1093/nar/gkae077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 01/05/2024] [Accepted: 01/26/2024] [Indexed: 02/09/2024] Open
Abstract
It is now widely accepted that aberrant splicing of constitutive exons is often caused by mutations affecting cis-acting splicing regulatory elements (SREs), but there is a misconception that all exons have an equal dependency on SREs and thus a similar vulnerability to aberrant splicing. We demonstrate that some exons are more likely to be affected by exonic splicing mutations (ESMs) due to an inherent vulnerability, which is context dependent and influenced by the strength of exon definition. We have developed VulExMap, a tool which is based on empirical data that can designate whether a constitutive exon is vulnerable. Using VulExMap, we find that only 25% of all exons can be categorized as vulnerable, whereas two-thirds of 359 previously reported ESMs in 75 disease genes are located in vulnerable exons. Because VulExMap analysis is based on empirical data on splicing of exons in their endogenous context, it includes all features important in determining the vulnerability. We believe that VulExMap will be an important tool when assessing the effect of exonic mutations by pinpointing whether they are located in exons vulnerable to ESMs.
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Affiliation(s)
- Lise L Holm
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Katharina K Flugt
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Rikke Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
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7
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Cantara S, Simoncelli G, Ricci C. Antisense Oligonucleotides (ASOs) in Motor Neuron Diseases: A Road to Cure in Light and Shade. Int J Mol Sci 2024; 25:4809. [PMID: 38732027 PMCID: PMC11083842 DOI: 10.3390/ijms25094809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/23/2024] [Accepted: 04/26/2024] [Indexed: 05/13/2024] Open
Abstract
Antisense oligonucleotides (ASOs) are short oligodeoxynucleotides designed to bind to specific regions of target mRNA. ASOs can modulate pre-mRNA splicing, increase levels of functional proteins, and decrease levels of toxic proteins. ASOs are being developed for the treatment of motor neuron diseases (MNDs), including spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS) and spinal and bulbar muscular atrophy (SBMA). The biggest success has been the ASO known as nusinersen, the first effective therapy for SMA, able to improve symptoms and slow disease progression. Another success is tofersen, an ASO designed to treat ALS patients with SOD1 gene mutations. Both ASOs have been approved by the FDA and EMA. On the other hand, ASO treatment in ALS patients with the C9orf72 gene mutation did not show any improvement in disease progression. The aim of this review is to provide an up-to-date overview of ASO research in MNDs, from preclinical studies to clinical trials and, where available, regulatory approval. We highlight the successes and failures, underline the strengths and limitations of the current ASO research, and suggest possible approaches that could lead to more effective treatments.
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Affiliation(s)
- Silvia Cantara
- Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy;
| | - Giorgia Simoncelli
- Unit of Neurology and Clinical Neurophysiology, Department of Neurological and Motor Sciences, Azienda Ospedaliero-Universitaria Senese, 53100 Siena, Italy;
| | - Claudia Ricci
- Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy;
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8
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White DS, Dunyak BM, Vaillancourt FH, Hoskins AA. A Sequential Binding Mechanism for 5' Splice Site Recognition and Modulation for the Human U1 snRNP. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.18.590139. [PMID: 38659798 PMCID: PMC11042371 DOI: 10.1101/2024.04.18.590139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Splice site recognition is essential for defining the transcriptome. Drugs like risdiplam and branaplam change how U1 snRNP recognizes particular 5' splice sites (5'SS) and promote U1 snRNP binding and splicing at these locations. Despite the therapeutic potential of 5'SS modulators, the complexity of their interactions and snRNP substrates have precluded defining a mechanism for 5'SS modulation. We have determined a sequential binding mechanism for modulation of -1A bulged 5'SS by branaplam using a combination of ensemble kinetic measurements and colocalization single molecule spectroscopy (CoSMoS). Our mechanism establishes that U1-C protein binds reversibly to U1 snRNP, and branaplam binds to the U1 snRNP/U1-C complex only after it has engaged a -1A bulged 5'SS. Obligate orders of binding and unbinding explain how reversible branaplam interactions cause formation of long-lived U1 snRNP/5'SS complexes. Branaplam is a ribonucleoprotein, not RNA duplex alone, targeting drug whose action depends on fundamental properties of 5'SS recognition.
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Affiliation(s)
- David S. White
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI
- Present Address: Element Biosciences, San Diego, CA
| | | | | | - Aaron A. Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI
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9
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Suárez-Herrera N, Garanto A, Collin RWJ. Understanding and Rescuing the Splicing Defect Caused by the Frequent ABCA4 Variant c.4253+43G>A Underlying Stargardt Disease. Nucleic Acid Ther 2024; 34:73-82. [PMID: 38466963 DOI: 10.1089/nat.2023.0076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024] Open
Abstract
Pathogenic variants in ABCA4 are the underlying molecular cause of Stargardt disease (STGD1), an autosomal recessive macular dystrophy characterized by a progressive loss of central vision. Among intronic ABCA4 variants, c.4253+43G>A is frequently detected in STGD1 cases and is classified as a hypomorphic allele, generally associated with late-onset cases. This variant was previously reported to alter splicing regulatory sequences, but the splicing outcome is not fully understood yet. In this study, we attempted to better understand its effect on splicing and to rescue the aberrant splicing via antisense oligonucleotides (AONs). Wild-type and c.4253+43G>A variant-harboring maxigene vectors revealed additional skipping events, which were not previously detected upon transfection in HEK293T cells. To restore exon inclusion, we designed a set of 27 AONs targeting either splicing silencer motifs or the variant region and screened these in maxigene-transfected HEK293T cells. Candidate AONs able to promote exon inclusion were selected for further testing in patient-derived photoreceptor precursor cells. Surprisingly, no robust splicing modulation was observed in this model system. Overall, this research helped to adequately characterize the splicing alteration caused by the c.4253+43G>A variant, although future development of AON-mediated exon inclusion therapy for ABCA4 is needed.
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Affiliation(s)
- Nuria Suárez-Herrera
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alejandro Garanto
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Pediatrics, Amalia Children's Hospital, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
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10
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Wu K, Bu F, Wu Y, Zhang G, Wang X, He S, Liu MF, Chen R, Yuan H. Exploring noncoding variants in genetic diseases: from detection to functional insights. J Genet Genomics 2024; 51:111-132. [PMID: 38181897 DOI: 10.1016/j.jgg.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 12/26/2023] [Accepted: 01/01/2024] [Indexed: 01/07/2024]
Abstract
Previous studies on genetic diseases predominantly focused on protein-coding variations, overlooking the vast noncoding regions in the human genome. The development of high-throughput sequencing technologies and functional genomics tools has enabled the systematic identification of functional noncoding variants. These variants can impact gene expression, regulation, and chromatin conformation, thereby contributing to disease pathogenesis. Understanding the mechanisms that underlie the impact of noncoding variants on genetic diseases is indispensable for the development of precisely targeted therapies and the implementation of personalized medicine strategies. The intricacies of noncoding regions introduce a multitude of challenges and research opportunities. In this review, we introduce a spectrum of noncoding variants involved in genetic diseases, along with research strategies and advanced technologies for their precise identification and in-depth understanding of the complexity of the noncoding genome. We will delve into the research challenges and propose potential solutions for unraveling the genetic basis of rare and complex diseases.
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Affiliation(s)
- Ke Wu
- Institute of Rare Diseases, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China
| | - Fengxiao Bu
- Institute of Rare Diseases, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China
| | - Yang Wu
- Institute of Rare Diseases, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China
| | - Gen Zhang
- Institute of Rare Diseases, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China
| | - Xin Wang
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang 310024, China
| | - Shunmin He
- Key Laboratory of RNA Biology, Center for Big Data Research in Health, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mo-Fang Liu
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang 310024, China; State Key Laboratory of Molecular Biology, State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, China.
| | - Runsheng Chen
- Key Laboratory of RNA Biology, Center for Big Data Research in Health, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Huijun Yuan
- Institute of Rare Diseases, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China.
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11
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Rashid S, Dimitriadi M. Autophagy in spinal muscular atrophy: from pathogenic mechanisms to therapeutic approaches. Front Cell Neurosci 2024; 17:1307636. [PMID: 38259504 PMCID: PMC10801191 DOI: 10.3389/fncel.2023.1307636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 12/14/2023] [Indexed: 01/24/2024] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by the depletion of the ubiquitously expressed survival motor neuron (SMN) protein. While the genetic cause of SMA has been well documented, the exact mechanism(s) by which SMN depletion results in disease progression remain elusive. A wide body of evidence has highlighted the involvement and dysregulation of autophagy in SMA. Autophagy is a highly conserved lysosomal degradation process which is necessary for cellular homeostasis; defects in the autophagic machinery have been linked with a wide range of neurodegenerative disorders, including amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. The pathway is particularly known to prevent neurodegeneration and has been suggested to act as a neuroprotective factor, thus presenting an attractive target for novel therapies for SMA patients. In this review, (a) we provide for the first time a comprehensive summary of the perturbations in the autophagic networks that characterize SMA development, (b) highlight the autophagic regulators which may play a key role in SMA pathogenesis and (c) propose decreased autophagic flux as the causative agent underlying the autophagic dysregulation observed in these patients.
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Affiliation(s)
| | - Maria Dimitriadi
- School of Life and Medical Science, University of Hertfordshire, Hatfield, United Kingdom
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12
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Li W, Li X, Gao Y, Xiong C, Tang Z. Emerging roles of RNA binding proteins in intervertebral disc degeneration and osteoarthritis. Orthop Surg 2023; 15:3015-3025. [PMID: 37803912 PMCID: PMC10694020 DOI: 10.1111/os.13851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 07/06/2023] [Accepted: 07/19/2023] [Indexed: 10/08/2023] Open
Abstract
The etiology of intervertebral disc degeneration (IDD) and osteoarthritis (OA) is complex and multifactorial. Both predisposing genes and environmental factors are involved in the pathogenesis of IDD and OA. Moreover, epigenetic modifications affect the development of IDD and OA. Dysregulated phenotypes of nucleus pulposus (NP) cells and OA chondrocytes, including apoptosis, extracellular matrix disruption, inflammation, and angiogenesis, are involved at all developmental stages of IDD and OA. RNA binding proteins (RBPs) have recently been recognized as essential post-transcriptional regulators of gene expression. RBPs are implicated in many cellular processes, such as proliferation, differentiation, and apoptosis. Recently, several RBPs have been reported to be associated with the pathogenesis of IDD and OA. This review briefly summarizes the current knowledge on the RNA-regulatory networks controlled by RBPs and their potential roles in the pathogenesis of IDD and OA. These initial findings support the idea that specific modulation of RBPs represents a promising approach for managing IDD and OA.
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Affiliation(s)
- Wen Li
- Department of EmergencyGeneral Hospital of Central Theater Command of PLAWuhanChina
| | - Xing‐Hua Li
- Department of EmergencyGeneral Hospital of Central Theater Command of PLAWuhanChina
| | - Yang Gao
- Department of OrthopaedicGeneral Hospital of Central Theater Command of PLAWuhanChina
| | - Cheng‐Jie Xiong
- Department of OrthopaedicGeneral Hospital of Central Theater Command of PLAWuhanChina
| | - Zhong‐Zhi Tang
- Department of EmergencyGeneral Hospital of Central Theater Command of PLAWuhanChina
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13
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Mura-Escorche G, Perdomo-Ramírez A, Ramos-Trujillo E, Trujillo-Frías CJ, Claverie-Martín F. Characterization of pre-mRNA Splicing Defects Caused by CLCN5 and OCRL Mutations and Identification of Novel Variants Associated with Dent Disease. Biomedicines 2023; 11:3082. [PMID: 38002082 PMCID: PMC10669864 DOI: 10.3390/biomedicines11113082] [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: 09/29/2023] [Revised: 11/08/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
Dent disease (DD) is an X-linked renal tubulopathy characterized by low-molecular-weight proteinuria, hypercalciuria, nephrocalcinosis, nephrolithiasis and progressive renal failure. Two-thirds of cases are associated with inactivating variants in the CLCN5 gene (Dent disease 1, DD1) and a few present variants in the OCRL gene (Dent disease 2, DD2). The aim of the present study was to test the effect on the pre-mRNA splicing process of DD variants, described here or in the literature, and describe the clinical and genotypic features of thirteen unrelated patients with suspected DD. All patients presented tubular proteinuria, ten presented hypercalciuria and five had nephrolithiasis or nephrocalcinosis. CLCN5 and OCRL genes were analyzed by Sanger sequencing. Nine patients showed variants in CLCN5 and four in OCRL; eight of these were new. Bioinformatics tools were used to select fifteen variants with a potential effect on pre-mRNA splicing from our patients' group and from the literature, and were experimentally tested using minigene assays. Results showed that three exonic missense mutations and two intronic variants affect the mRNA splicing process. Our findings widen the genotypic spectrum of DD and provide insight into the impact of variants causing DD.
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Affiliation(s)
- Glorián Mura-Escorche
- Unidad de Investigación, Grupo RenalTube, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain; (G.M.-E.); (A.P.-R.); (C.J.T.-F.)
- Departamento de Medicina Interna, Dermatología y Psiquiatría, Facultad de Medicina, Universidad de la Laguna, 38071 Santa Cruz de Tenerife, Spain
| | - Ana Perdomo-Ramírez
- Unidad de Investigación, Grupo RenalTube, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain; (G.M.-E.); (A.P.-R.); (C.J.T.-F.)
| | - Elena Ramos-Trujillo
- Unidad de Investigación, Grupo RenalTube, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain; (G.M.-E.); (A.P.-R.); (C.J.T.-F.)
- Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de la Laguna, 38071 Santa Cruz de Tenerife, Spain
| | - Carmen Jane Trujillo-Frías
- Unidad de Investigación, Grupo RenalTube, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain; (G.M.-E.); (A.P.-R.); (C.J.T.-F.)
| | - Félix Claverie-Martín
- Unidad de Investigación, Grupo RenalTube, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain; (G.M.-E.); (A.P.-R.); (C.J.T.-F.)
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14
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Sparmann A, Vogel J. RNA-based medicine: from molecular mechanisms to therapy. EMBO J 2023; 42:e114760. [PMID: 37728251 PMCID: PMC10620767 DOI: 10.15252/embj.2023114760] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/24/2023] [Accepted: 08/29/2023] [Indexed: 09/21/2023] Open
Abstract
RNA-based therapeutics have the potential to revolutionize the treatment and prevention of human diseases. While early research faced setbacks, it established the basis for breakthroughs in RNA-based drug design that culminated in the extraordinarily fast development of mRNA vaccines to combat the COVID-19 pandemic. We have now reached a pivotal moment where RNA medicines are poised to make a broad impact in the clinic. In this review, we present an overview of different RNA-based strategies to generate novel therapeutics, including antisense and RNAi-based mechanisms, mRNA-based approaches, and CRISPR-Cas-mediated genome editing. Using three rare genetic diseases as examples, we highlight the opportunities, but also the challenges to wide-ranging applications of this class of drugs.
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Affiliation(s)
- Anke Sparmann
- Helmholtz Institute for RNA‐based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI)WürzburgGermany
| | - Jörg Vogel
- Helmholtz Institute for RNA‐based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI)WürzburgGermany
- Institute of Molecular Infection Biology (IMIB)University of WürzburgWürzburgGermany
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15
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Jiang T, Qu R, Liu X, Hou Y, Wang L, Hua Y. HnRNPR strongly represses splicing of a critical exon associated with spinal muscular atrophy through binding to an exonic AU-rich element. J Med Genet 2023; 60:1105-1115. [PMID: 37225410 DOI: 10.1136/jmg-2023-109186] [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: 01/27/2023] [Accepted: 05/08/2023] [Indexed: 05/26/2023]
Abstract
BACKGROUND Spinal muscular atrophy (SMA) is a motor neuron disease caused by mutations of survival of motor neuron 1 (SMN1) gene, which encodes the SMN protein. SMN2, a nearly identical copy of SMN1, with several single-nucleotide substitutions leading to predominant skipping of its exon 7, is insufficient to compensate for loss of SMN1. Heterogeneous nuclear ribonucleoprotein R (hnRNPR) has been previously shown to interact with SMN in the 7SK complex in motoneuron axons and is implicated in the pathogenesis of SMA. Here, we show that hnRNPR also interacts with SMN1/2 pre-mRNAs and potently inhibits exon 7 inclusion. METHODS In this study, to examine the mechanism that hnRNPR regulates SMN1/2 splicing, deletion analysis in an SMN2 minigene system, RNA-affinity chromatography, co-overexpression analysis and tethering assay were performed. We screened antisense oligonucleotides (ASOs) in a minigene system and identified a few that markedly promoted SMN2 exon 7 splicing. RESULTS We pinpointed an AU-rich element located towards the 3' end of the exon that mediates splicing repression by hnRNPR. We uncovered that both hnRNPR and Sam68 bind to the element in a competitive manner, and the inhibitory effect of hnRNPR is much stronger than Sam68. Moreover, we found that, among the four hnRNPR splicing isoforms, the exon 5-skipped one has the minimal inhibitory effect, and ASOs inducing hnRNPR exon 5 skipping also promote SMN2 exon 7 inclusion. CONCLUSION We identified a novel mechanism that contributes to mis-splicing of SMN2 exon 7.
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Affiliation(s)
- Tao Jiang
- Department of Neurology and Suzhou Clinical Research Center of Neurological Disease, Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
- Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, China
| | - Ruobing Qu
- Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, China
- College of Chemistry Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, China
| | - Xuan Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Nanjing Normal University College of Life Sciences, Nanjing, Jiangsu, China
| | - Yanjun Hou
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Nanjing Normal University College of Life Sciences, Nanjing, Jiangsu, China
| | - Li Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Nanjing Normal University College of Life Sciences, Nanjing, Jiangsu, China
| | - Yimin Hua
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Nanjing Normal University College of Life Sciences, Nanjing, Jiangsu, China
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16
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Yang X, Zhang B, Wang S, Lu Y, Chen K, Luo C, Sun A, Zhang H. OTTM: an automated classification tool for translational drug discovery from omics data. Brief Bioinform 2023; 24:bbad301. [PMID: 37594310 PMCID: PMC10516341 DOI: 10.1093/bib/bbad301] [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: 05/29/2023] [Revised: 07/22/2023] [Accepted: 07/31/2023] [Indexed: 08/19/2023] Open
Abstract
Omics data from clinical samples are the predominant source of target discovery and drug development. Typically, hundreds or thousands of differentially expressed genes or proteins can be identified from omics data. This scale of possibilities is overwhelming for target discovery and validation using biochemical or cellular experiments. Most of these proteins and genes have no corresponding drugs or even active compounds. Moreover, a proportion of them may have been previously reported as being relevant to the disease of interest. To facilitate translational drug discovery from omics data, we have developed a new classification tool named Omics and Text driven Translational Medicine (OTTM). This tool can markedly narrow the range of proteins or genes that merit further validation via drug availability assessment and literature mining. For the 4489 candidate proteins identified in our previous proteomics study, OTTM recommended 40 FDA-approved or clinical trial drugs. Of these, 15 are available commercially and were tested on hepatocellular carcinoma Hep-G2 cells. Two drugs-tafenoquine succinate (an FDA-approved antimalarial drug targeting CYC1) and branaplam (a Phase 3 clinical drug targeting SMN1 for the treatment of spinal muscular atrophy)-showed potent inhibitory activity against Hep-G2 cell viability, suggesting that CYC1 and SMN1 may be potential therapeutic target proteins for hepatocellular carcinoma. In summary, OTTM is an efficient classification tool that can accelerate the discovery of effective drugs and targets using thousands of candidate proteins identified from omics data. The online and local versions of OTTM are available at http://otter-simm.com/ottm.html.
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Affiliation(s)
- Xiaobo Yang
- ShanghaiTech University
- School of Life Science and Technology, ShanghaiTech University, 393 Huaxiazhong Road, Shanghai 200031, China
| | - Bei Zhang
- Shanghai Institute of Materia Medica
- Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
| | - Siqi Wang
- Beijing Proteome Research Center
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, and National Center for Protein Sciences (Beijing)
| | - Ye Lu
- Nanjing University of Chinese Medicine
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China; Chemical Biology Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Kaixian Chen
- academician medicinal scientist of the Chinese Academy of Sciences
- Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China; School of Life Science and Technology, ShanghaiTech University, 393 Huaxiazhong Road, Shanghai 200031, China; School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Cheng Luo
- Shanghai Institute of Materia Medica
- Chemical Biology Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China; School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Aihua Sun
- Beijing Proteome Research Center
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics; Research Unit of Proteomics-driven Cancer Precision Medicine, Chinese Academy of Medical Sciences
| | - Hao Zhang
- Shanghai Institute of Materia Medica
- Chemical Biology Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
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17
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Papaioannou I, Owen JS, Yáñez‐Muñoz RJ. Clinical applications of gene therapy for rare diseases: A review. Int J Exp Pathol 2023; 104:154-176. [PMID: 37177842 PMCID: PMC10349259 DOI: 10.1111/iep.12478] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 03/08/2023] [Accepted: 04/16/2023] [Indexed: 05/15/2023] Open
Abstract
Rare diseases collectively exact a high toll on society due to their sheer number and overall prevalence. Their heterogeneity, diversity, and nature pose daunting clinical challenges for both management and treatment. In this review, we discuss recent advances in clinical applications of gene therapy for rare diseases, focusing on a variety of viral and non-viral strategies. The use of adeno-associated virus (AAV) vectors is discussed in the context of Luxturna, licenced for the treatment of RPE65 deficiency in the retinal epithelium. Imlygic, a herpes virus vector licenced for the treatment of refractory metastatic melanoma, will be an example of oncolytic vectors developed against rare cancers. Yescarta and Kymriah will showcase the use of retrovirus and lentivirus vectors in the autologous ex vivo production of chimeric antigen receptor T cells (CAR-T), licenced for the treatment of refractory leukaemias and lymphomas. Similar retroviral and lentiviral technology can be applied to autologous haematopoietic stem cells, exemplified by Strimvelis and Zynteglo, licenced treatments for adenosine deaminase-severe combined immunodeficiency (ADA-SCID) and β-thalassaemia respectively. Antisense oligonucleotide technologies will be highlighted through Onpattro and Tegsedi, RNA interference drugs licenced for familial transthyretin (TTR) amyloidosis, and Spinraza, a splice-switching treatment for spinal muscular atrophy (SMA). An initial comparison of the effectiveness of AAV and oligonucleotide therapies in SMA is possible with Zolgensma, an AAV serotype 9 vector, and Spinraza. Through these examples of marketed gene therapies and gene cell therapies, we will discuss the expanding applications of such novel technologies to previously intractable rare diseases.
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Affiliation(s)
| | - James S. Owen
- Division of MedicineUniversity College LondonLondonUK
| | - Rafael J. Yáñez‐Muñoz
- AGCTlab.orgCentre of Gene and Cell TherapyCentre for Biomedical SciencesDepartment of Biological SciencesSchool of Life Sciences and the EnvironmentRoyal Holloway University of LondonEghamUK
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18
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Nishio H, Niba ETE, Saito T, Okamoto K, Takeshima Y, Awano H. Spinal Muscular Atrophy: The Past, Present, and Future of Diagnosis and Treatment. Int J Mol Sci 2023; 24:11939. [PMID: 37569314 PMCID: PMC10418635 DOI: 10.3390/ijms241511939] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/17/2023] [Accepted: 07/21/2023] [Indexed: 08/13/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a lower motor neuron disease with autosomal recessive inheritance. The first cases of SMA were reported by Werdnig in 1891. Although the phenotypic variation of SMA led to controversy regarding the clinical entity of the disease, the genetic homogeneity of SMA was proved in 1990. Five years later, in 1995, the gene responsible for SMA, SMN1, was identified. Genetic testing of SMN1 has enabled precise epidemiological studies, revealing that SMA occurs in 1 of 10,000 to 20,000 live births and that more than 95% of affected patients are homozygous for SMN1 deletion. In 2016, nusinersen was the first drug approved for treatment of SMA in the United States. Two other drugs were subsequently approved: onasemnogene abeparvovec and risdiplam. Clinical trials with these drugs targeting patients with pre-symptomatic SMA (those who were diagnosed by genetic testing but showed no symptoms) revealed that such patients could achieve the milestones of independent sitting and/or walking. Following the great success of these trials, population-based newborn screening programs for SMA (more precisely, SMN1-deleted SMA) have been increasingly implemented worldwide. Early detection by newborn screening and early treatment with new drugs are expected to soon become the standards in the field of SMA.
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Affiliation(s)
- Hisahide Nishio
- Faculty of Rehabilitation, Kobe Gakuin University, 518 Arise, Ikawadani-cho, Nishi-ku, Kobe 651-2180, Japan
| | - Emma Tabe Eko Niba
- Laboratory of Molecular and Biochemical Research, Biomedical Research Core Facilities, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan;
| | - Toshio Saito
- Department of Neurology, National Hospital Organization Osaka Toneyama Medical Center, 5-1-1 Toneyama, Toyonaka 560-8552, Japan;
| | - Kentaro Okamoto
- Department of Pediatrics, Ehime Prefectural Imabari Hospital, 4-5-5 Ishi-cho, Imabari 794-0006, Japan;
| | - Yasuhiro Takeshima
- Department of Pediatrics, Hyogo Medical University, 1-1 Mukogawacho, Nishinomiya 663-8501, Japan;
| | - Hiroyuki Awano
- Organization for Research Initiative and Promotion, Research Initiative Center, Tottori University, 86 Nishi-cho, Yonago 683-8503, Japan;
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19
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Ottesen EW, Singh NN, Luo D, Kaas B, Gillette B, Seo J, Jorgensen H, Singh RN. Diverse targets of SMN2-directed splicing-modulating small molecule therapeutics for spinal muscular atrophy. Nucleic Acids Res 2023; 51:5948-5980. [PMID: 37026480 PMCID: PMC10325915 DOI: 10.1093/nar/gkad259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 03/13/2023] [Accepted: 03/28/2023] [Indexed: 04/08/2023] Open
Abstract
Designing an RNA-interacting molecule that displays high therapeutic efficacy while retaining specificity within a broad concentration range remains a challenging task. Risdiplam is an FDA-approved small molecule for the treatment of spinal muscular atrophy (SMA), the leading genetic cause of infant mortality. Branaplam is another small molecule which has undergone clinical trials. The therapeutic merit of both compounds is based on their ability to restore body-wide inclusion of Survival Motor Neuron 2 (SMN2) exon 7 upon oral administration. Here we compare the transcriptome-wide off-target effects of these compounds in SMA patient cells. We captured concentration-dependent compound-specific changes, including aberrant expression of genes associated with DNA replication, cell cycle, RNA metabolism, cell signaling and metabolic pathways. Both compounds triggered massive perturbations of splicing events, inducing off-target exon inclusion, exon skipping, intron retention, intron removal and alternative splice site usage. Our results of minigenes expressed in HeLa cells provide mechanistic insights into how these molecules targeted towards a single gene produce different off-target effects. We show the advantages of combined treatments with low doses of risdiplam and branaplam. Our findings are instructive for devising better dosing regimens as well as for developing the next generation of small molecule therapeutics aimed at splicing modulation.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Diou Luo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Bailey Kaas
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Benjamin J Gillette
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Hannah J Jorgensen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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20
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Arbab M, Matuszek Z, Kray KM, Du A, Newby GA, Blatnik AJ, Raguram A, Richter MF, Zhao KT, Levy JM, Shen MW, Arnold WD, Wang D, Xie J, Gao G, Burghes AHM, Liu DR. Base editing rescue of spinal muscular atrophy in cells and in mice. Science 2023; 380:eadg6518. [PMID: 36996170 PMCID: PMC10270003 DOI: 10.1126/science.adg6518] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/21/2023] [Indexed: 04/01/2023]
Abstract
Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, arises from survival motor neuron (SMN) protein insufficiency resulting from SMN1 loss. Approved therapies circumvent endogenous SMN regulation and require repeated dosing or may wane. We describe genome editing of SMN2, an insufficient copy of SMN1 harboring a C6>T mutation, to permanently restore SMN protein levels and rescue SMA phenotypes. We used nucleases or base editors to modify five SMN2 regulatory regions. Base editing converted SMN2 T6>C, restoring SMN protein levels to wild type. Adeno-associated virus serotype 9-mediated base editor delivery in Δ7SMA mice yielded 87% average T6>C conversion, improved motor function, and extended average life span, which was enhanced by one-time base editor and nusinersen coadministration (111 versus 17 days untreated). These findings demonstrate the potential of a one-time base editing treatment for SMA.
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Affiliation(s)
- Mandana Arbab
- Department of Neurology, Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Zaneta Matuszek
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Kaitlyn M. Kray
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA
| | - Ailing Du
- Horae Gene Therapy Center, University of Massachusetts, Medical School, Worcester, MA 01605, USA
| | - Gregory A. Newby
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Anton J. Blatnik
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA
| | - Aditya Raguram
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Michelle F. Richter
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Kevin T. Zhao
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Jonathan M. Levy
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Max W. Shen
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - W. David Arnold
- Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA
- NextGen Precision Health, University of Missouri, Columbia, MO 65212, USA
| | - Dan Wang
- Horae Gene Therapy Center, University of Massachusetts, Medical School, Worcester, MA 01605, USA
- Horae Gene Therapy Center and RNA Therapeutics Institute, University of Massachusetts, Medical School, Worcester, MA 01605, USA
| | - Jun Xie
- Horae Gene Therapy Center, University of Massachusetts, Medical School, Worcester, MA 01605, USA
| | - Guangping Gao
- Horae Gene Therapy Center, University of Massachusetts, Medical School, Worcester, MA 01605, USA
- Microbiology and Physiological Systems, University of Massachusetts, Medical School, Worcester, MA 01605, USA
| | - Arthur H. M. Burghes
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA
| | - David R. Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
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21
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Tse V, Chacaltana G, Gutierrez M, Forino NM, Jimenez AG, Tao H, Do PH, Oh C, Chary P, Quesada I, Hamrick A, Lee S, Stone MD, Sanford JR. Rescue of blood coagulation Factor VIII exon-16 mis-splicing by antisense oligonucleotides. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.31.535160. [PMID: 37034721 PMCID: PMC10081312 DOI: 10.1101/2023.03.31.535160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The human Factor VIII ( F8 ) protein is essential for the blood coagulation cascade and specific F8 mutations cause the rare bleeding disorder Hemophilia A (HA). Here, we investigated the impact of HA-causing single-nucleotide mutations on F8 pre-mRNA splicing. We found that 14/97 (∼14.4%) coding sequence mutations tested in our study induced exon skipping. Splicing patterns of 4/11 (∼36.4%) F8 exons tested were especially sensitive to the presence of common disease-causing mutations. RNA-chemical probing analyses revealed a three-way junction structure at the 3' end of intron 15 (TWJ-3-15). TWJ-3-15 sequesters the polypyrimidine tract, a key determinant of 3' splice site strength. Using exon-16 of the F8 gene as a model, we designed specific antisense oligonucleotides (ASOs) that target TWJ-3-15 and identified three that promote the splicing of F8 exon-16. Interaction of TWJ-3-15 with ASOs increases accessibility of the polypyrimidine tract and inhibits the binding of hnRNPA1-dependent splicing silencing factors. Moreover, ASOs targeting TWJ-3-15 rescue diverse splicing-sensitive HA-causing mutations, most of which are distal to the 3' splice site being impacted. The TWJ-3-15 structure and its effect on mRNA splicing provide a model for HA etiology in patients harboring specific F8 mutations and provide a framework for precision RNA-based HA therapies.
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22
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Nadal M, Anton R, Dorca‐Arévalo J, Estébanez‐Perpiñá E, Tizzano EF, Fuentes‐Prior P. Structure and function analysis of Sam68 and hnRNP A1 synergy in the exclusion of exon 7 from SMN2 transcripts. Protein Sci 2023; 32:e4553. [PMID: 36560896 PMCID: PMC10031812 DOI: 10.1002/pro.4553] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 12/13/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by the absence of a functional copy of the Survival of Motor Neuron 1 gene (SMN1). The nearly identical paralog, SMN2, cannot compensate for the loss of SMN1 because exon 7 is aberrantly skipped from most SMN2 transcripts, a process mediated by synergistic activities of Src-associated during mitosis, 68 kDa (Sam68/KHDRBS1) and heterogeneous nuclear ribonucleoprotein (hnRNP) A1. This results in the production of a truncated, nonfunctional protein that is rapidly degraded. Here, we present several crystal structures of Sam68 RNA-binding domain (RBD). Sam68-RBD forms stable symmetric homodimers by antiparallel association of helices α3 from two monomers. However, the details of domain organization and the dimerization interface differ significantly from previously characterized homologs. We demonstrate that Sam68 and hnRNP A1 can simultaneously bind proximal motifs within the central region of SMN2 (ex7). Furthermore, we show that the RNA-binding pockets of the two proteins are close to each other in their heterodimeric complex and identify contact residues using crosslinking-mass spectrometry. We present a model of the ternary Sam68·SMN2 (ex7)·hnRNP A1 complex that reconciles all available information on SMN1/2 splicing. Our findings have important implications for the etiology of SMA and open new avenues for the design of novel therapeutics to treat splicing diseases.
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Affiliation(s)
- Marta Nadal
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
| | - Rosa Anton
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
| | - Jonatan Dorca‐Arévalo
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
- Present address:
Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Campus of BellvitgeHospitalet de Llobregat, University of BarcelonaBarcelonaSpain
| | - Eva Estébanez‐Perpiñá
- Structural Biology of Nuclear Receptors, Department of Biochemistry and Molecular Biomedicine, Faculty of BiologyInstitute of Biomedicine (IBUB) of the University of Barcelona (UB)BarcelonaSpain
| | - Eduardo F. Tizzano
- Medicine Genetics GroupVall d'Hebron Research Institute (VHIR)BarcelonaSpain
- Department of Clinical and Molecular GeneticsHospital Vall d'HebronBarcelonaSpain
| | - Pablo Fuentes‐Prior
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
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Strathmann EA, Hölker I, Tschernoster N, Hosseinibarkooie S, Come J, Martinat C, Altmüller J, Wirth B. Epigenetic regulation of plastin 3 expression by the macrosatellite DXZ4 and the transcriptional regulator CHD4. Am J Hum Genet 2023; 110:442-459. [PMID: 36812914 PMCID: PMC10027515 DOI: 10.1016/j.ajhg.2023.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 02/03/2023] [Indexed: 02/23/2023] Open
Abstract
Dysregulated Plastin 3 (PLS3) levels associate with a wide range of skeletal and neuromuscular disorders and the most common types of solid and hematopoietic cancer. Most importantly, PLS3 overexpression protects against spinal muscular atrophy. Despite its crucial role in F-actin dynamics in healthy cells and its involvement in many diseases, the mechanisms that regulate PLS3 expression are unknown. Interestingly, PLS3 is an X-linked gene and all asymptomatic SMN1-deleted individuals in SMA-discordant families who exhibit PLS3 upregulation are female, suggesting that PLS3 may escape X chromosome inactivation. To elucidate mechanisms contributing to PLS3 regulation, we performed a multi-omics analysis in two SMA-discordant families using lymphoblastoid cell lines and iPSC-derived spinal motor neurons originated from fibroblasts. We show that PLS3 tissue-specifically escapes X-inactivation. PLS3 is located ∼500 kb proximal to the DXZ4 macrosatellite, which is essential for X chromosome inactivation. By applying molecular combing in a total of 25 lymphoblastoid cell lines (asymptomatic individuals, individuals with SMA, control subjects) with variable PLS3 expression, we found a significant correlation between the copy number of DXZ4 monomers and PLS3 levels. Additionally, we identified chromodomain helicase DNA binding protein 4 (CHD4) as an epigenetic transcriptional regulator of PLS3 and validated co-regulation of the two genes by siRNA-mediated knock-down and overexpression of CHD4. We show that CHD4 binds the PLS3 promoter by performing chromatin immunoprecipitation and that CHD4/NuRD activates the transcription of PLS3 by dual-luciferase promoter assays. Thus, we provide evidence for a multilevel epigenetic regulation of PLS3 that may help to understand the protective or disease-associated PLS3 dysregulation.
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Affiliation(s)
- Eike A Strathmann
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Irmgard Hölker
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Nikolai Tschernoster
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Cologne Center for Genomics and West German Genome Center, University of Cologne, 50931 Cologne, Germany
| | - Seyyedmohsen Hosseinibarkooie
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Julien Come
- INSERM/ UEVE UMR 861, Université Paris Saclay, I-STEM, 91100 Corbeil-Essonnes, France
| | - Cecile Martinat
- INSERM/ UEVE UMR 861, Université Paris Saclay, I-STEM, 91100 Corbeil-Essonnes, France
| | - Janine Altmüller
- Cologne Center for Genomics and West German Genome Center, University of Cologne, 50931 Cologne, Germany
| | - Brunhilde Wirth
- Institute of Human Genetics, University Hospital of Cologne, University Cologne, Kerpener Str. 34, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Rare Diseases, University Hospital of Cologne, 50931 Cologne, Germany.
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24
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Therapeutic strategies for autism: targeting three levels of the central dogma of molecular biology. Transl Psychiatry 2023; 13:58. [PMID: 36792602 PMCID: PMC9931756 DOI: 10.1038/s41398-023-02356-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/17/2023] Open
Abstract
The past decade has yielded much success in the identification of risk genes for Autism Spectrum Disorder (ASD), with many studies implicating loss-of-function (LoF) mutations within these genes. Despite this, no significant clinical advances have been made so far in the development of therapeutics for ASD. Given the role of LoF mutations in ASD etiology, many of the therapeutics in development are designed to rescue the haploinsufficient effect of genes at the transcriptional, translational, and protein levels. This review will discuss the various therapeutic techniques being developed from each level of the central dogma with examples including: CRISPR activation (CRISPRa) and gene replacement at the DNA level, antisense oligonucleotides (ASOs) at the mRNA level, and small-molecule drugs at the protein level, followed by a review of current delivery methods for these therapeutics. Since central nervous system (CNS) penetrance is of utmost importance for ASD therapeutics, it is especially necessary to evaluate delivery methods that have higher efficiency in crossing the blood-brain barrier (BBB).
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25
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Younger DS. Spinal cord motor disorders. HANDBOOK OF CLINICAL NEUROLOGY 2023; 196:3-42. [PMID: 37620076 DOI: 10.1016/b978-0-323-98817-9.00007-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Spinal cord diseases are frequently devastating due to the precipitous and often permanently debilitating nature of the deficits. Spastic or flaccid paraparesis accompanied by dermatomal and myotomal signatures complementary to the incurred deficits facilitates localization of the insult within the cord. However, laboratory studies often employing disease-specific serology, neuroradiology, neurophysiology, and cerebrospinal fluid analysis aid in the etiologic diagnosis. While many spinal cord diseases are reversible and treatable, especially when recognized early, more than ever, neuroscientists are being called to investigate endogenous mechanisms of neural plasticity. This chapter is a review of the embryology, neuroanatomy, clinical localization, evaluation, and management of adult and childhood spinal cord motor disorders.
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Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
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26
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Hammond SM, Abendroth F, Goli L, Stoodley J, Burrell M, Thom G, Gurrell I, Ahlskog N, Gait MJ, Wood MJ, Webster CI. Antibody-oligonucleotide conjugate achieves CNS delivery in animal models for spinal muscular atrophy. JCI Insight 2022; 7:154142. [PMID: 36346674 PMCID: PMC7614086 DOI: 10.1172/jci.insight.154142] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
Antisense oligonucleotides (ASOs) have emerged as one of the most innovative new genetic drug modalities. However, their high molecular weight limits their bioavailability for otherwise-treatable neurological disorders. We investigated conjugation of ASOs to an antibody against the murine transferrin receptor, 8D3130, and evaluated it via systemic administration in mouse models of the neurodegenerative disease spinal muscular atrophy (SMA). SMA, like several other neurological and neuromuscular diseases, is treatable with single-stranded ASOs that modulate splicing of the survival motor neuron 2 (SMN2) gene. Administration of 8D3130-ASO conjugate resulted in elevated levels of bioavailability to the brain. Additionally, 8D3130-ASO yielded therapeutic levels of SMN2 splicing in the central nervous system of adult human SMN2-transgenic (hSMN2-transgenic) mice, which resulted in extended survival of a severely affected SMA mouse model. Systemic delivery of nucleic acid therapies with brain-targeting antibodies offers powerful translational potential for future treatments of neuromuscular and neurodegenerative diseases.
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Affiliation(s)
- Suzan M Hammond
- Department of Paediatrics, John Radcliffe Hospital, and.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | - Frank Abendroth
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom.,Department of Chemistry, Philipps Universität-Marburg, Marburg, Germany
| | - Larissa Goli
- Department of Paediatrics, John Radcliffe Hospital, and.,Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jessica Stoodley
- Department of Paediatrics, John Radcliffe Hospital, and.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | | | | | - Ian Gurrell
- Neuroscience, Biopharmaceuticals, AstraZeneca, Cambridge, United Kingdom
| | - Nina Ahlskog
- Department of Paediatrics, John Radcliffe Hospital, and.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | - Michael J Gait
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Matthew Ja Wood
- Department of Paediatrics, John Radcliffe Hospital, and.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
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Qiu J, Qu R, Lin M, Xu J, Zhu Q, Zhang Z, Sun J. Position-dependent effects of hnRNP A1/A2 in SMN1/2 exon7 splicing. BIOCHIMICA ET BIOPHYSICA ACTA (BBA) - GENE REGULATORY MECHANISMS 2022; 1865:194875. [DOI: 10.1016/j.bbagrm.2022.194875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/08/2022] [Accepted: 09/28/2022] [Indexed: 11/07/2022]
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28
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Rozza R, Janoš P, Spinello A, Magistrato A. Role of computational and structural biology in the development of small-molecule modulators of the spliceosome. Expert Opin Drug Discov 2022; 17:1095-1109. [PMID: 35983696 DOI: 10.1080/17460441.2022.2114452] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
INTRODUCTION RNA splicing is a pivotal step of eukaryotic gene expression during which the introns are excised from the precursor (pre-)RNA and the exons are joined together to form mature RNA products (i.e a protein-coding mRNA or long non-coding (lnc)RNAs). The spliceosome, a complex ribonucleoprotein machine, performs pre-RNA splicing with extreme precision. Deregulated splicing is linked to cancer, genetic, and neurodegenerative diseases. Hence, the discovery of small-molecules targeting core spliceosome components represents an appealing therapeutic opportunity. AREA COVERED Several atomic-level structures of the spliceosome and distinct splicing-modulators bound to its protein/RNA components have been solved. Here, we review recent advances in the discovery of small-molecule splicing-modulators, discuss opportunities and challenges for their therapeutic applicability, and showcase how structural data and/or all-atom simulations can illuminate key facets of their mechanism, thus contributing to future drug-discovery campaigns. EXPERT OPINION This review highlights the potential of modulating pre-RNA splicing with small-molecules, and anticipates how the synergy of computer and wet-lab experiments will enrich our understanding of splicing regulation/deregulation mechanisms. This information will aid future structure-based drug-discovery efforts aimed to expand the currently limited portfolio of selective splicing-modulators.
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Affiliation(s)
- Riccardo Rozza
- National Research Council of Italy, Institute of Materials-foundry (CNR-IOM) C/o SISSA, Trieste, Italy
| | - Pavel Janoš
- National Research Council of Italy, Institute of Materials-foundry (CNR-IOM) C/o SISSA, Trieste, Italy
| | - Angelo Spinello
- Department of Biological, Chemical and Pharmaceutical Sciences, University of Palermo, Palermo, Italy
| | - Alessandra Magistrato
- National Research Council of Italy, Institute of Materials-foundry (CNR-IOM) C/o SISSA, Trieste, Italy
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29
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Zilio E, Piano V, Wirth B. Mitochondrial Dysfunction in Spinal Muscular Atrophy. Int J Mol Sci 2022; 23:ijms231810878. [PMID: 36142791 PMCID: PMC9503857 DOI: 10.3390/ijms231810878] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by recessive mutations in the SMN1 gene, globally affecting ~8-14 newborns per 100,000. The severity of the disease depends on the residual levels of functional survival of motor neuron protein, SMN. SMN is a ubiquitously expressed RNA binding protein involved in a plethora of cellular processes. In this review, we discuss the effects of SMN loss on mitochondrial functions in the neuronal and muscular systems that are the most affected in patients with spinal muscular atrophy. Our aim is to highlight how mitochondrial defects may contribute to disease progression and how restoring mitochondrial functionality may be a promising approach to develop new therapies. We also collected from previous studies a list of transcripts encoding mitochondrial proteins affected in various SMA models. Moreover, we speculate that in adulthood, when motor neurons require only very low SMN levels, the natural deterioration of mitochondria associated with aging may be a crucial triggering factor for adult spinal muscular atrophy, and this requires particular attention for therapeutic strategies.
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Affiliation(s)
- Eleonora Zilio
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
| | - Valentina Piano
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Correspondence: (V.P.); (B.W.)
| | - Brunhilde Wirth
- Institute of Human Genetics, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
- Correspondence: (V.P.); (B.W.)
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30
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Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disorder caused by mutations in SMN1 (encoding survival motor neuron protein (SMN)). Reduced expression of SMN leads to loss of α-motor neurons, severe muscle weakness and often early death. Standard-of-care recommendations for multidisciplinary supportive care of SMA were established in the past few decades. However, improved understanding of the pathogenetic mechanisms of SMA has led to the development of different therapeutic approaches. Three treatments that increase SMN expression by distinct molecular mechanisms, administration routes and tissue biodistributions have received regulatory approval with others in clinical development. The advent of the new therapies is redefining standards of care as in many countries most patients are treated with one of the new therapies, leading to the identification of emerging new phenotypes of SMA and a renewed characterization of demographics owing to improved patient survival.
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31
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Targeted-Deletion of a Tiny Sequence via Prime Editing to Restore SMN Expression. Int J Mol Sci 2022; 23:ijms23147941. [PMID: 35887289 PMCID: PMC9317564 DOI: 10.3390/ijms23147941] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/13/2022] [Accepted: 07/17/2022] [Indexed: 01/27/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating autosomal recessive motor neuron disease associated with mutations in the survival motor neuron 1 (SMN1) gene, the leading genetic cause of infant mortality. A nearly identical copy gene (SMN2) is retained in almost all patients with SMA. However, SMN2 fails to prevent disease development because of its alternative splicing, leading to a lack of exon 7 in the majority of SMN2 transcripts and yielding an unstable truncated protein. Several splicing regulatory elements, including intronic splicing silencer-N1 (ISS-N1) of SMN2 have been described. In this study, targeted-deletion of ISS-N1 was achieved using prime editing (PE) in SMA patient-specific induced pluripotent stem cells (SMA-iPSCs) with a high efficiency of 7/24. FL-SMN expression was restored in the targeted-deletion iPS clones and their derived motor neurons (iMNs). Notably, the apoptosis of the iMNs, caused by the loss of SMN protein that leads to the hyperactivity of endoplasmic reticulum (ER) stress, was alleviated in targeted-deletion iPSCs derived-iMNs. Thus, this is the first study to demonstrate that the targeted-deletion of ISS-N1 via PE for restoring FL-SMN expression holds therapeutic promise for SMA.
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32
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Singh NN, O'Leary CA, Eich T, Moss WN, Singh RN. Structural Context of a Critical Exon of Spinal Muscular Atrophy Gene. Front Mol Biosci 2022; 9:928581. [PMID: 35847983 PMCID: PMC9283826 DOI: 10.3389/fmolb.2022.928581] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
Humans contain two nearly identical copies of Survival Motor Neuron genes, SMN1 and SMN2. Deletion or mutation of SMN1 causes spinal muscular atrophy (SMA), one of the leading genetic diseases associated with infant mortality. SMN2 is unable to compensate for the loss of SMN1 due to predominant exon 7 skipping, leading to the production of a truncated protein. Antisense oligonucleotide and small molecule-based strategies aimed at the restoration of SMN2 exon 7 inclusion are approved therapies of SMA. Many cis-elements and transacting factors have been implicated in regulation of SMN exon 7 splicing. Also, several structural elements, including those formed by a long-distance interaction, have been implicated in the modulation of SMN exon 7 splicing. Several of these structures have been confirmed by enzymatic and chemical structure-probing methods. Additional structures formed by inter-intronic interactions have been predicted by computational algorithms. SMN genes generate a vast repertoire of circular RNAs through inter-intronic secondary structures formed by inverted Alu repeats present in large number in SMN genes. Here, we review the structural context of the exonic and intronic cis-elements that promote or prevent exon 7 recognition. We discuss how structural rearrangements triggered by single nucleotide substitutions could bring drastic changes in SMN2 exon 7 splicing. We also propose potential mechanisms by which inter-intronic structures might impact the splicing outcomes.
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Affiliation(s)
- Natalia N. Singh
- Department of Biomedical Science, Iowa State University, Ames, IA, United States
| | - Collin A. O'Leary
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
| | - Taylor Eich
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
| | - Walter N. Moss
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
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Muinos-Bühl A, Rombo R, Janzen E, Ling KK, Hupperich K, Rigo F, Bennett CF, Wirth B. Combinatorial ASO-mediated therapy with low dose SMN and the protective modifier Chp1 is not sufficient to ameliorate SMA pathology hallmarks. Neurobiol Dis 2022; 171:105795. [PMID: 35724821 DOI: 10.1016/j.nbd.2022.105795] [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: 03/01/2022] [Revised: 05/17/2022] [Accepted: 06/14/2022] [Indexed: 10/18/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a devastating genetically inherited neuromuscular disorder characterized by the progressive loss of motor neurons in the spinal cord, leading to muscle atrophy and weakness. Although SMA is caused by homozygous mutations in SMN1, the disease severity is mainly determined by the copy number of SMN2, an almost identical gene that produces ~10% correctly spliced SMN transcripts. Recently, three FDA- and EMA-approved therapies that either increase correctly spliced SMN2 transcripts (nusinersen and risdiplam) or replace SMN1 (onasemnogen abeparvovec-xioi) have revolutionized the clinical outcome in SMA patients. However, for severely affected SMA individuals carrying only two SMN2 copies even a presymptomatic therapy might be insufficient to fully counteract disease development. Therefore, SMN-independent compounds supporting SMN-dependent therapies represent a promising therapeutic approach. Recently, we have shown a significant amelioration of SMA disease hallmarks in a severely affected SMA mouse carrying a mutant Chp1 allele when combined with low-dose of SMN antisense oligonucleotide (ASO) treatment. CHP1 is a direct interacting partner of PLS3, a strong protective modifier of SMA. Both proteins ameliorate impaired endocytosis in SMA and significantly restore pathological hallmarks in mice. Here, we aimed to pharmacologically reduce CHP1 levels in an ASO-based combinatorial therapy targeting SMN and Chp1. Chp1 modulation is a major challenge since its genetic reduction to ~50% has shown to ameliorate SMA pathology, while the downregulation below that level causes cerebellar ataxia. Efficacy and tolerability studies determined that a single injection of 30 μg Chp1-ASO4 in the CNS is a safe dosage that significantly reduced CHP1 levels to ~50% at postnatal day (PND)14. Unfortunately, neither electrophysiological predictors such as compound muscle action potential (CMAP) or motor unit number estimation (MUNE) nor histological hallmarks of SMA in neuromuscular junction (NMJ), spinal cord or muscle were ameliorated in SMA mice treated with Chp1-ASO4 compared to CTRL-ASO at PND21. Surprisingly, CHP1 levels were almost at control level 4-weeks post injection, indicating a rather short-term effect of the ASO. Therefore, we re-administrated Chp1-ASO4 by i.c.v. bolus injection at PND28. However, no significant improvement of SMA hallmarks were seen at 2 month-of-age either. In conclusion, in contrast to the protective effect of genetically-induced Chp1 reduction on SMA, combinatorial therapy with Chp1- and SMN-ASOs failed to significantly ameliorate the SMA pathology. Chp1-ASOs compared to SMN-ASO proved to have rather short-term effect and even reinjection had no significant impact on SMA progression, suggesting that further optimization of the ASO may be required to fully explore the combination.
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Affiliation(s)
- A Muinos-Bühl
- Institute of Human Genetics, University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany.
| | - R Rombo
- Institute of Human Genetics, University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany.
| | - E Janzen
- Institute of Human Genetics, University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - K K Ling
- Ionis Pharmaceuticals, Carlsbad, CA 92008, USA.
| | - K Hupperich
- Institute of Human Genetics, University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - F Rigo
- Ionis Pharmaceuticals, Carlsbad, CA 92008, USA.
| | - C F Bennett
- Ionis Pharmaceuticals, Carlsbad, CA 92008, USA.
| | - B Wirth
- Institute of Human Genetics, University of Cologne, 50931 Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; Institute for Genetics, University of Cologne, 50674 Cologne, Germany; Center for Rare Diseases, University Hospital of Cologne, 50931 Cologne, Germany.
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34
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López-Cortés A, Echeverría-Garcés G, Ramos-Medina MJ. Molecular Pathogenesis and New Therapeutic Dimensions for Spinal Muscular Atrophy. BIOLOGY 2022; 11:biology11060894. [PMID: 35741415 PMCID: PMC9219894 DOI: 10.3390/biology11060894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/04/2022] [Accepted: 05/06/2022] [Indexed: 11/16/2022]
Abstract
The condition known as 5q spinal muscular atrophy (SMA) is a devastating autosomal recessive neuromuscular disease caused by a deficiency of the ubiquitous protein survival of motor neuron (SMN), which is encoded by the SMN1 and SMN2 genes. It is one of the most common pediatric recessive genetic diseases, and it represents the most common cause of hereditary infant mortality. After decades of intensive basic and clinical research efforts, and improvements in the standard of care, successful therapeutic milestones have been developed, delaying the progression of 5q SMA and increasing patient survival. At the same time, promising data from early-stage clinical trials have indicated that additional therapeutic options are likely to emerge in the near future. Here, we provide updated information on the molecular underpinnings of SMA; we also provide an overview of the rapidly evolving therapeutic landscape for SMA, including SMN-targeted therapies, SMN-independent therapies, and combinational therapies that are likely to be key for the development of treatments that are effective across a patient’s lifespan.
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Affiliation(s)
- Andrés López-Cortés
- Programa de Investigación en Salud Global, Facultad de Ciencias de la Salud, Universidad Internacional SEK, Quito 170302, Ecuador
- Facultad de Medicina, Universidad de Las Américas, Quito 170124, Ecuador
- Latin American Network for the Implementation and Validation of Clinical Pharmacogenomics Guidelines (RELIVAF-CYTED), 28001 Madrid, Spain; (G.E.-G.); (M.J.R.-M.)
- Correspondence:
| | - Gabriela Echeverría-Garcés
- Latin American Network for the Implementation and Validation of Clinical Pharmacogenomics Guidelines (RELIVAF-CYTED), 28001 Madrid, Spain; (G.E.-G.); (M.J.R.-M.)
| | - María José Ramos-Medina
- Latin American Network for the Implementation and Validation of Clinical Pharmacogenomics Guidelines (RELIVAF-CYTED), 28001 Madrid, Spain; (G.E.-G.); (M.J.R.-M.)
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Kanda S, Moulton E, Butchbach MER. Effects of inhibitors of SLC9A-type sodium-protein exchangers on Survival Motor Neuron 2 ( SMN2) mRNA splicing and expression. Mol Pharmacol 2022; 102:92-105. [PMID: 35667685 PMCID: PMC9341265 DOI: 10.1124/molpharm.122.000529] [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: 03/15/2022] [Accepted: 05/09/2022] [Indexed: 11/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive, pediatric-onset disorder caused by the loss of spinal motor neurons thereby leading to muscle atrophy. SMA is caused by the loss of or mutations in the survival motor neuron 1 (SMN1) gene. SMN1 is duplicated in humans to give rise to the paralogous SMN2 gene. This paralog is nearly identical except for a cytosine to thymine (C-to-T) transition within an exonic splicing enhancer (ESE) element within exon 7. As a result, the majority of SMN2 transcripts lack exon 7 (SMNΔ7) which produces a truncated and unstable SMN protein. Since SMN2 copy number is inversely related to disease severity, it is a well-established target for SMA therapeutics development. 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of sodium/proton exchangers (NHEs), has previously been shown to increase exon 7 inclusion and SMN protein levels in SMA cells. In this study, NHE inhibitors were evaluated for their ability to modulate SMN2 expression. EIPA as well as 5-(N,N-hexamethylene)amiloride (HMA) increase exon 7 inclusion in SMN2 splicing reporter lines as well as in SMA fibroblasts. The EIPA-induced exon 7 inclusion occurs via a unique mechanism that does not involve previously identified splicing factors. Transcriptome analysis identified novel targets, including TIA1 and FABP3, for further characterization. EIPA and HMA are more selective at inhibiting the NHE5 isoform, which is expressed in fibroblasts as well as in neuronal cells. These results show that NHE5 inhibition increases SMN2 expression and may be a novel target for therapeutics development. Significance Statement This study demonstrates a molecular mechanism by which inhibitors of the sodium-protein exchanger increase the alternative splicing of SMN2 in spinal muscular atrophy cells. NHE5 selective inhibitors increase the inclusion of full-length SMN2 mRNAs by targeting TIA1 and FABP3 expression, which is distinct from other small molecule regulators of SMN2 alternative splicing. This study provides a novel means to increase full-length SMN2 expression and a novel target for therapeutics development.
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Affiliation(s)
- Sambee Kanda
- Biological Sciences, University of Delaware, United States
| | - Emily Moulton
- Biomedical Research, Nemours Children's Hospital Delaware, United States
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Hjartarson HT, Nathorst-Böös K, Sejersen T. Disease Modifying Therapies for the Management of Children with Spinal Muscular Atrophy (5q SMA): An Update on the Emerging Evidence. Drug Des Devel Ther 2022; 16:1865-1883. [PMID: 35734367 PMCID: PMC9208376 DOI: 10.2147/dddt.s214174] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 06/01/2022] [Indexed: 11/23/2022] Open
Abstract
SMA (5q SMA) is an autosomal recessive neuromuscular disease with an estimated incidence of approximately 1 in 11,000 live births, characterized by progressive degeneration and loss of α-motor neurons in the spinal cord and brain stem, resulting in progressive muscle weakness. The disease spectrum is wide, from a serious congenital to a mild adult-onset disease. SMA is caused by biallelic mutations in the SMN1 gene and disease severity is modified primarily by SMN2 copy number. Before the advent of specific disease altering treatments, SMA was the second most common fatal autosomal recessive disorder after cystic fibrosis and the most common genetic cause of infant mortality. Nusinersen, risdiplam, and onasemnogene abeparvovec are presently the only approved disease modifying therapies for SMA, and the aim of this review is to discuss their mode of action, effects, safety concerns, and results from real-world experience. All exert their action by increasing the level of SMN protein in lower motor neuron. Nusinersen and risdiplam by modifying the SMN2 gene product, and onasemnogene abeparvovec by delivering SMN1 gene copies into cells. All have an established clinical efficacy. An important feature shared by all three is that early intervention is associated with a better treatment outcome, such that in cases where treatment is initiated in an early pre-symptomatic period, it may result in normal – or almost normal – motor development. Thus, early diagnosis followed by swift initiation of treatment is fundamental for the treatment response and consequently long-term prognosis in SMA type 1, and probably SMA type 2. The same principle similarly applies to the milder phenotypes. All three therapies are relatively novel, with risdiplam being the latest addition. Except for nusinersen, real-world data are still scarce, and long-term data are quite naturally lacking.
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Affiliation(s)
- Helgi Thor Hjartarson
- Department of Neuropediatrics, Astrid Lindgren Children´s Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Kristofer Nathorst-Böös
- Department of Neuropediatrics, Astrid Lindgren Children´s Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Thomas Sejersen
- Department of Neuropediatrics, Astrid Lindgren Children´s Hospital, Karolinska University Hospital, Stockholm, Sweden
- Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
- Correspondence: Thomas Sejersen, Department of Women’s and Children’s Health, Karolinska Institute, Karolinska Vägen 37A, Stockholm, 171 76, Sweden, Tel +46 8 51777342, Email
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Zhang L, Abendroth F, Vázquez O. A Chemical Biology Perspective to Therapeutic Regulation of RNA Splicing in Spinal Muscular Atrophy (SMA). ACS Chem Biol 2022; 17:1293-1307. [PMID: 35639849 DOI: 10.1021/acschembio.2c00161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Manipulation of RNA splicing machinery has emerged as a drug modality. Here, we illustrate the potential of this novel paradigm to correct aberrant splicing events focused on the recent therapeutic advances in spinal muscular atrophy (SMA). SMA is an incurable neuromuscular disorder and at present the primary genetic cause of early infant death. This Review summarizes the exciting journey from the first reported SMA cases to the currently approved splicing-switching treatments, i.e., antisense oligonucleotides and small-molecule modifiers. We emphasize both chemical structures and molecular bases for recognition. We briefly discuss the advantages and disadvantages of these treatments and include the remaining challenges and future directions. Finally, we also predict that these success stories will contribute to further therapies for human diseases by RNA-splicing control.
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Affiliation(s)
- Lei Zhang
- Department of Chemistry, University of Marburg, Hans-Meerwein-Straße 4, 35043, Marburg, Germany
| | - Frank Abendroth
- Department of Chemistry, University of Marburg, Hans-Meerwein-Straße 4, 35043, Marburg, Germany
| | - Olalla Vázquez
- Department of Chemistry, University of Marburg, Hans-Meerwein-Straße 4, 35043, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), University of Marburg, Karl-von-Frisch-Straße 14, 35043 Marburg, Germany
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Schlautmann LP, Lackmann JW, Altmüller J, Dieterich C, Boehm V, Gehring NH. Exon junction complex-associated multi-adapter RNPS1 nucleates splicing regulatory complexes to maintain transcriptome surveillance. Nucleic Acids Res 2022; 50:5899-5918. [PMID: 35640609 PMCID: PMC9178013 DOI: 10.1093/nar/gkac428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 05/05/2022] [Accepted: 05/10/2022] [Indexed: 12/04/2022] Open
Abstract
The exon junction complex (EJC) is an RNA-binding multi-protein complex with critical functions in post-transcriptional gene regulation. It is deposited on the mRNA during splicing and regulates diverse processes including pre-mRNA splicing and nonsense-mediated mRNA decay (NMD) via various interacting proteins. The peripheral EJC-binding protein RNPS1 was reported to serve two insufficiently characterized functions: suppressing mis-splicing of cryptic splice sites and activating NMD in the cytoplasm. The analysis of transcriptome-wide effects of EJC and RNPS1 knockdowns in different human cell lines supports the conclusion that RNPS1 can moderately influence NMD activity, but is not a globally essential NMD factor. However, numerous aberrant splicing events strongly suggest that the main function of RNPS1 is splicing regulation. Rescue analyses revealed that the RRM and C-terminal domain of RNPS1 both contribute partially to regulate RNPS1-dependent splicing events. We defined the RNPS1 core interactome using complementary immunoprecipitations and proximity labeling, which identified interactions with splicing-regulatory factors that are dependent on the C-terminus or the RRM domain of RNPS1. Thus, RNPS1 emerges as a multifunctional splicing regulator that promotes correct and efficient splicing of different vulnerable splicing events via the formation of diverse splicing-promoting complexes.
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Affiliation(s)
- Lena P Schlautmann
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50937 Cologne, Germany
| | - Jan-Wilm Lackmann
- CECAD Research Center, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Janine Altmüller
- Cologne Center for Genomics (CCG), University of Cologne, 50931 Cologne, Germany
| | - Christoph Dieterich
- Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III and Klaus Tschira Institute for Integrative Computational Cardiology, Heidelberg University Hospital, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Volker Boehm
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50937 Cologne, Germany
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50937 Cologne, Germany
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Advanced Gene-Targeting Therapies for Motor Neuron Diseases and Muscular Dystrophies. Int J Mol Sci 2022; 23:ijms23094824. [PMID: 35563214 PMCID: PMC9101723 DOI: 10.3390/ijms23094824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/22/2022] [Accepted: 04/25/2022] [Indexed: 12/19/2022] Open
Abstract
Gene therapy is a revolutionary, cutting-edge approach to permanently ameliorate or amend many neuromuscular diseases by targeting their genetic origins. Motor neuron diseases and muscular dystrophies, whose genetic causes are well known, are the frontiers of this research revolution. Several genetic treatments, with diverse mechanisms of action and delivery methods, have been approved during the past decade and have demonstrated remarkable results. However, despite the high number of genetic treatments studied preclinically, those that have been advanced to clinical trials are significantly fewer. The most clinically advanced treatments include adeno-associated virus gene replacement therapy, antisense oligonucleotides, and RNA interference. This review provides a comprehensive overview of the advanced gene therapies for motor neuron diseases (i.e., amyotrophic lateral sclerosis and spinal muscular atrophy) and muscular dystrophies (i.e., Duchenne muscular dystrophy, limb-girdle muscular dystrophy, and myotonic dystrophy) tested in clinical trials. Emphasis has been placed on those methods that are a few steps away from their authoritative approval.
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40
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Toosaranont J, Ruschadaariyachat S, Mujchariyakul W, Arora JK, Charoensawan V, Suktitipat B, Palmer TN, Fletcher S, Wilton SD, Mitrpant C. Antisense Oligonucleotide Induction of the hnRNPA1b Isoform Affects Pre-mRNA Splicing of SMN2 in SMA Type I Fibroblasts. Int J Mol Sci 2022; 23:ijms23073937. [PMID: 35409296 PMCID: PMC8999010 DOI: 10.3390/ijms23073937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/22/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a severe, debilitating neuromuscular condition characterised by loss of motor neurons and progressive muscle wasting. SMA is caused by a loss of expression of SMN1 that encodes the survival motor neuron (SMN) protein necessary for the survival of motor neurons. Restoration of SMN expression through increased inclusion of SMN2 exon 7 is known to ameliorate symptoms in SMA patients. As a consequence, regulation of pre-mRNA splicing of SMN2 could provide a potential molecular therapy for SMA. In this study, we explored if splice switching antisense oligonucleotides could redirect the splicing repressor hnRNPA1 to the hnRNPA1b isoform and restore SMN expression in fibroblasts from a type I SMA patient. Antisense oligonucleotides (AOs) were designed to promote exon 7b retention in the mature mRNA and induce the hnRNPA1b isoform. RT-PCR and western blot analysis were used to assess and monitor the efficiency of different AO combinations. A combination of AOs targeting multiple silencing motifs in hnRNPA1 pre-mRNA led to robust hnRNPA1b induction, which, in turn, significantly increased expression of full-length SMN (FL-SMN) protein. A combination of PMOs targeting the same motifs also strongly induced hnRNPA1b isoform, but surprisingly SMN2 exon 5 skipping was detected, and the PMO cocktail did not lead to a significant increase in expression of FL-SMN protein. We further performed RNA sequencing to assess the genome-wide effects of hnRNPA1b induction. Some 3244 genes were differentially expressed between the hnRNPA1b-induced and untreated SMA fibroblasts, which are functionally enriched in cell cycle and chromosome segregation processes. RT-PCR analysis demonstrated that expression of the master regulator of these enrichment pathways, MYBL2 and FOXM1B, were reduced in response to PMO treatment. These findings suggested that induction of hnRNPA1b can promote SMN protein expression, but not at sufficient levels to be clinically relevant.
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Affiliation(s)
- Jarichad Toosaranont
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
| | - Sukanya Ruschadaariyachat
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
| | - Warasinee Mujchariyakul
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10700, Thailand; (W.M.); (J.K.A.); (V.C.)
| | - Jantarika Kumar Arora
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10700, Thailand; (W.M.); (J.K.A.); (V.C.)
| | - Varodom Charoensawan
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10700, Thailand; (W.M.); (J.K.A.); (V.C.)
- Integrative Computational BioScience (ICBS) Center, Mahidol University, Nakhon Pathom 73170, Thailand
- Systems Biology of Diseases Research Unit, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Bhoom Suktitipat
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
- Integrative Computational BioScience (ICBS) Center, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Thomas N. Palmer
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
| | - Sue Fletcher
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA 6150, Australia
| | - Steve D. Wilton
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA 6150, Australia
| | - Chalermchai Mitrpant
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA 6150, Australia
- Correspondence:
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41
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Reprogramming RNA processing: an emerging therapeutic landscape. Trends Pharmacol Sci 2022; 43:437-454. [PMID: 35331569 DOI: 10.1016/j.tips.2022.02.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/13/2022]
Abstract
The production of a mature mRNA requires coordination of multiple processing steps, which ultimately control its content, localization, and stability. These steps include some of the largest macromolecular machines in the cell, which were, until recently, considered undruggable due to their biological complexity. Building from an expanded understanding of the underlying mechanisms that drive these processes, a new wave of therapeutics is seeking to target RNA processing. With a focus on impacting gene regulation at the RNA level, such modalities offer potential for sequence-specific resolution in drug design. Here, we review our current understanding of RNA-processing events and their role in gene regulation, with a focus on the therapeutic opportunities that have emerged within this landscape.
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42
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Jacquier V, Prévot M, Gostan T, Bordonné R, Benkhelifa-Ziyyat S, Barkats M, Soret J. Splicing efficiency of minor introns in a mouse model of SMA predominantly depends on their branchpoint sequence and can involve the contribution of major spliceosome components. RNA (NEW YORK, N.Y.) 2022; 28:303-319. [PMID: 34893560 PMCID: PMC8848931 DOI: 10.1261/rna.078329.120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 11/22/2021] [Indexed: 06/14/2023]
Abstract
Spinal muscular atrophy (SMA) is a devastating neurodegenerative disease caused by reduced amounts of the ubiquitously expressed Survival of Motor Neuron (SMN) protein. In agreement with its crucial role in the biogenesis of spliceosomal snRNPs, SMN-deficiency is correlated to numerous splicing alterations in patient cells and various tissues of SMA mouse models. Among the snRNPs whose assembly is impacted by SMN-deficiency, those involved in the minor spliceosome are particularly affected. Importantly, splicing of several, but not all U12-dependent introns has been shown to be affected in different SMA models. Here, we have investigated the molecular determinants of this differential splicing in spinal cords from SMA mice. We show that the branchpoint sequence (BPS) is a key element controlling splicing efficiency of minor introns. Unexpectedly, splicing of several minor introns with suboptimal BPS is not affected in SMA mice. Using in vitro splicing experiments and oligonucleotides targeting minor or major snRNAs, we show for the first time that splicing of these introns involves both the minor and major machineries. Our results strongly suggest that splicing of a subset of minor introns is not affected in SMA mice because components of the major spliceosome compensate for the loss of minor splicing activity.
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Affiliation(s)
- Valentin Jacquier
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier 34293, France
| | - Manon Prévot
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier 34293, France
| | - Thierry Gostan
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier 34293, France
| | - Rémy Bordonné
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier 34293, France
| | - Sofia Benkhelifa-Ziyyat
- Centre de Recherche en Myologie (CRM), Institut de Myologie, Sorbonne Universités, UPMC Univ Paris 06, Inserm UMRS974, GH Pitié Salpêtrière, Paris 75013, France
| | - Martine Barkats
- Centre de Recherche en Myologie (CRM), Institut de Myologie, Sorbonne Universités, UPMC Univ Paris 06, Inserm UMRS974, GH Pitié Salpêtrière, Paris 75013, France
| | - Johann Soret
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier 34293, France
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43
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Dominguez CE, Cunningham D, Venkataramany AS, Chandler DS. Heat increases full-length SMN splicing: promise for splice-augmenting therapies for SMA. Hum Genet 2022; 141:239-256. [PMID: 35088120 DOI: 10.1007/s00439-021-02408-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 11/30/2021] [Indexed: 11/28/2022]
Abstract
Spinal muscular atrophy (SMA) is a debilitating neurodegenerative pediatric disease characterized by low levels of the survival motor protein (SMN). Humans have two SMN genes that produce identical SMN proteins, but they differ at a key nucleotide in exon 7 that induces differential mRNA splicing. SMN1 primarily produces full-length SMN protein, but due to the spliceosome's inability to efficiently recognize exon 7, SMN2 transcripts are often truncated. SMA occurs primarily through mutations or deletions in the SMN1 gene; therefore, current therapies use antisense oligonucleotides (ASOs) to target exon 7 inclusion in SMN2 mRNA and promote full-length SMN protein production. Here, we explore additional methods that can target SMN splicing and therapeutically increase full-length SMN protein. We demonstrate that in vitro heat treatment of cells increases exon 7 inclusion and relative abundance of full-length SMN2 mRNA and protein, a response that is modulated through the upregulation of the positive splicing factor TRA2 beta. We also observe that HSP90, but not HSP40 or HSP70, in the heat shock response is essential for SMN2 exon 7 splicing under hyperthermic conditions. Finally, we show that pulsatile heat treatments for one hour in vitro and in vivo are effective in increasing full-length SMN2 levels. These findings suggest that timed interval treatments could be a therapeutic alternative for SMA patients who do not respond to current ASO-based therapies or require a unique combination regimen.
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Affiliation(s)
- Catherine E Dominguez
- 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, 700 Children's Drive, Columbus, OH, 43205, USA
| | - David Cunningham
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA
| | - Akila S Venkataramany
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA.,Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH, USA.,Medical Scientist Training Program, The Ohio State University, 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, 700 Children's Drive, Columbus, OH, 43205, USA. .,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA.
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44
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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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45
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Jutzi D, Ruepp MD. Alternative Splicing in Human Biology and Disease. Methods Mol Biol 2022; 2537:1-19. [PMID: 35895255 DOI: 10.1007/978-1-0716-2521-7_1] [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] [Indexed: 06/15/2023]
Abstract
Alternative pre-mRNA splicing allows for the production of multiple mRNAs from an individual gene, which not only expands the protein-coding potential of the genome but also enables complex mechanisms for the post-transcriptional control of gene expression. Regulation of alternative splicing entails a combinatorial interplay between an abundance of trans-acting splicing factors, cis-acting regulatory sequence elements and their concerted effects on the core splicing machinery. Given the extent and biological significance of alternative splicing in humans, it is not surprising that aberrant splicing patterns can cause or contribute to a wide range of diseases. In this introductory chapter, we outline the mechanisms that govern alternative pre-mRNA splicing and its regulation and discuss how dysregulated splicing contributes to human diseases affecting the motor system and the brain.
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Affiliation(s)
- Daniel Jutzi
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK.
| | - Marc-David Ruepp
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK.
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46
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Holm LL, Doktor TK, Hansen MB, Petersen USS, Andresen BS. Vulnerable exons, like ACADM exon 5, are highly dependent on maintaining a correct balance between splicing enhancers and silencers. Hum Mutat 2021; 43:253-265. [PMID: 34923709 DOI: 10.1002/humu.24321] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 11/08/2021] [Accepted: 12/15/2021] [Indexed: 12/22/2022]
Abstract
It is now widely accepted that aberrant splicing of constitutive exons is often caused by mutations affecting cis-acting splicing regulatory elements, but there is a misconception that all exons have an equal dependency on splicing regulatory elements and thus a similar susceptibility to aberrant splicing. We investigated exonic mutations in ACADM exon 5 to experimentally examine their effect on splicing and found that 7 out of 11 tested mutations affected exon inclusion, demonstrating that this constitutive exon is particularly vulnerable to exonic splicing mutations. Employing ACADM exon 5 and 6 as models, we demonstrate that the balance between splicing enhancers and silencers, flanking intron length, and flanking splice site strength are important factors that determine exon definition and splicing efficiency of the exon in question. Our study shows that two constitutive exons in ACADM have different inherent vulnerabilities to exonic splicing mutations. This suggests that in silico prediction of potential pathogenic effects on splicing from exonic mutations may be improved by also considering the inherent vulnerability of the exon. Moreover, we show that single nucleotide polymorphism that affect either of two different exonic splicing silencers, located far apart in exon 5, all protect against both immediately flanking and more distant exonic splicing mutations.
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Affiliation(s)
- Lise L Holm
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Michael B Hansen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M., Denmark.,Department of Molecular Biology and Biochemistry, The Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
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47
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Welby E, Rehborg RJ, Harmelink M, Ebert AD. Assessment of cerebral spinal fluid biomarkers and microRNA-mediated disease mechanisms in spinal muscular atrophy patient samples. Hum Mol Genet 2021; 31:1830-1843. [PMID: 34919695 DOI: 10.1093/hmg/ddab365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 12/01/2021] [Accepted: 12/09/2021] [Indexed: 11/14/2022] Open
Abstract
Cerebral spinal fluid (CSF) is a promising biospecimen for the detection of central nervous system biomarkers to monitor therapeutic efficacy at the cellular level in neurological diseases. Spinal muscular atrophy (SMA) patients receiving intrathecal antisense oligonucleotide (nusinersen) therapy tend to show improved motor function, but the treatment effect on cellular health remains unknown. The objective of this study was to assess the potential of extracellular RNAs and microRNAs in SMA patient CSF as indicators of neuron and glial health following nusinersen treatment. Extracellular RNA analysis of CSF samples revealed ongoing cellular stress related to inflammation and glial differentiation, even after treatment administration. Downregulated microRNA expression associated with SMA-specific or general motor neuron dysfunction in animal and cellular models, tended to increase in nusinersen treated patient CSF samples and correlated with SMA Type 1 and 2 motor functioning improvements. However, miR-146a, known to be upregulated in SMA induced pluripotent stem cell (iPSC)-derived astrocytes, showed increased expression in nusinersen treated CSF samples. We then used mRNA sequencing and multi-electrode arrays to assess the transcriptional and functional effects of miR-146a on healthy and SMA iPSC-derived motor neurons. miR-146a treatment on iPSC-derived motor neurons led to a downregulation of extracellular matrix genes associated with synaptic perineuronal net and alterations in spontaneous electrophysiological activity. Together, this study suggests that extracellular RNAs and microRNAs may serve as useful biomarkers to monitor cellular health during nusinersen treatment. Moreover, these data highlight the importance of addressing astrocyte health and response to nusinersen in SMA pathogenesis and treatment strategies.
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Affiliation(s)
- Emily Welby
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Rebecca J Rehborg
- Department of Neurology (Child Neurology), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Matthew Harmelink
- Department of Neurology (Child Neurology), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Allison D Ebert
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
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48
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Mirea A, Shelby ES, Axente M, Badina M, Padure L, Leanca M, Dima V, Sporea C. Combination Therapy with Nusinersen and Onasemnogene Abeparvovec-xioi in Spinal Muscular Atrophy Type I. J Clin Med 2021; 10:jcm10235540. [PMID: 34884240 PMCID: PMC8658131 DOI: 10.3390/jcm10235540] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/22/2021] [Accepted: 11/25/2021] [Indexed: 01/12/2023] Open
Abstract
Background: Spinal muscular atrophy (SMA) is a neuromuscular progressive disease, characterized by decreased amounts of survival motor neuron (SMN) protein, due to an autosomal recessive genetic defect. Despite recent research, there is still no cure. Nusinersen, an antisense oligonucleotide acting on the SMN2 gene, is intrathecally administered all life long, while onasemnogene abeparvovec-xioi, a gene therapy, is administered intravenously only once. Both therapies have proven efficacy, with best outcomes obtained when administered presymptomatically. In recent years, disease-modifying therapies such as nusinersen and onasemnogene abeparvovec-xioi have changed the natural history of SMA. Methods: We observed seven SMA type I patients, who received both therapies. We compared their motor function trajectories, ventilation hours and cough assist sessions to a control group of patients who received one therapy, in order to investigate whether combination therapy may be more effective than a single intervention alone. Results: Patients who received both therapies, compared to the monotherapy cohort, had the same motor function trajectory. Moreover, it was observed that the evolution of motor function was better in the 6 months following the first therapy than in the first 6 months after adding the second treatment. Conclusions: Our results suggest that early treatment is more important than combined therapy.
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Affiliation(s)
- Andrada Mirea
- Faculty of Midwifery and Nursing, University of Medicine and Pharmacy “Carol Davila”, 37 Dionisie Lupu Street, 020021 Bucharest, Romania; (M.A.); (M.B.); (C.S.)
- Scientific Research Nucleus, National University Center for Children Neurorehabilitation “Dr. Nicolae Robanescu”, 44 Dumitru Minca Street, 041408 Bucharest, Romania; (E.-S.S.); (L.P.); (M.L.)
- Correspondence:
| | - Elena-Silvia Shelby
- Scientific Research Nucleus, National University Center for Children Neurorehabilitation “Dr. Nicolae Robanescu”, 44 Dumitru Minca Street, 041408 Bucharest, Romania; (E.-S.S.); (L.P.); (M.L.)
| | - Mihaela Axente
- Faculty of Midwifery and Nursing, University of Medicine and Pharmacy “Carol Davila”, 37 Dionisie Lupu Street, 020021 Bucharest, Romania; (M.A.); (M.B.); (C.S.)
- Scientific Research Nucleus, National University Center for Children Neurorehabilitation “Dr. Nicolae Robanescu”, 44 Dumitru Minca Street, 041408 Bucharest, Romania; (E.-S.S.); (L.P.); (M.L.)
| | - Mihaela Badina
- Faculty of Midwifery and Nursing, University of Medicine and Pharmacy “Carol Davila”, 37 Dionisie Lupu Street, 020021 Bucharest, Romania; (M.A.); (M.B.); (C.S.)
- Scientific Research Nucleus, National University Center for Children Neurorehabilitation “Dr. Nicolae Robanescu”, 44 Dumitru Minca Street, 041408 Bucharest, Romania; (E.-S.S.); (L.P.); (M.L.)
| | - Liliana Padure
- Scientific Research Nucleus, National University Center for Children Neurorehabilitation “Dr. Nicolae Robanescu”, 44 Dumitru Minca Street, 041408 Bucharest, Romania; (E.-S.S.); (L.P.); (M.L.)
| | - Madalina Leanca
- Scientific Research Nucleus, National University Center for Children Neurorehabilitation “Dr. Nicolae Robanescu”, 44 Dumitru Minca Street, 041408 Bucharest, Romania; (E.-S.S.); (L.P.); (M.L.)
| | - Vlad Dima
- Clinical Hospital of Obstetrics and Gynecology “Filantropia”, 11 Ion Mihalache Avenue, 011132 Bucharest, Romania;
| | - Corina Sporea
- Faculty of Midwifery and Nursing, University of Medicine and Pharmacy “Carol Davila”, 37 Dionisie Lupu Street, 020021 Bucharest, Romania; (M.A.); (M.B.); (C.S.)
- Scientific Research Nucleus, National University Center for Children Neurorehabilitation “Dr. Nicolae Robanescu”, 44 Dumitru Minca Street, 041408 Bucharest, Romania; (E.-S.S.); (L.P.); (M.L.)
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49
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Kray KM, McGovern VL, Chugh D, Arnold WD, Burghes AHM. Dual SMN inducing therapies can rescue survival and motor unit function in symptomatic ∆7SMA mice. Neurobiol Dis 2021; 159:105488. [PMID: 34425216 PMCID: PMC8502210 DOI: 10.1016/j.nbd.2021.105488] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/06/2021] [Accepted: 08/16/2021] [Indexed: 11/24/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by survival motor neuron (SMN) protein deficiency which results in motor neuron loss and muscle atrophy. SMA is caused by a mutation or deletion of the survival motor neuron 1 (SMN1) gene and retention of the nearly identical SMN2 gene. SMN2 contains a C to T change in exon 7 that results in exon 7 exclusion from 90% of transcripts. SMN protein lacking exon 7 is unstable and rapidly degraded. The remaining full-length transcripts from SMN2 are insufficient for normal motor neuron function leading to the development of SMA. Three different therapeutic approaches that increase full-length SMN (FL-SMN) protein production are approved for treatment of SMA patients. Studies in both animal models and humans have demonstrated increasing SMN levels prior to onset of symptoms provides the greatest therapeutic benefit. Treatment of SMA, after some motor neuron loss has occurred, is also effective but to a lesser degree. The SMN∆7 mouse model is a well characterized model of severe or type 1 SMA, dying at 14 days of age. Here we treated three groups of ∆7SMA mice starting before, roughly during, and after symptom onset to determine if combining two mechanistically distinct SMN inducing therapies could improve the therapeutic outcome both before and after motor neuron loss. We found, compared with individual therapies, that morpholino antisense oligonucleotide (ASO) directed against ISS-N1 combined with the small molecule compound RG7800 significantly increased FL-SMN transcript and protein production resulting in improved survival and weight of ∆7SMA mice. Moreover, when give late symptomatically, motor unit function was completely rescued with no loss in function at 100 days of age in the dual treatment group. We have therefore shown that this dual therapeutic approach successfully increases SMN protein and rescues motor function in symptomatic ∆7SMA mice.
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Affiliation(s)
- Kaitlyn M Kray
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA.
| | - Vicki L McGovern
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA.
| | - Deepti Chugh
- Department of Neurology, Neuromuscular Division, The Ohio State University Wexner Medical Center, 395 W. 12(th) Ave, Columbus, OH 43210, USA
| | - W David Arnold
- Department of Neurology, Neuromuscular Division, The Ohio State University Wexner Medical Center, 395 W. 12(th) Ave, Columbus, OH 43210, USA.
| | - Arthur H M Burghes
- Department of Biological Chemistry and Pharmacology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Columbus, OH 43210, USA; Department of Neurology, Neuromuscular Division, The Ohio State University Wexner Medical Center, 395 W. 12(th) Ave, Columbus, OH 43210, USA.
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50
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Liu S, Kang WJ, Abrimian A, Xu J, Cartegni L, Majumdar S, Hesketh P, Bekker A, Pan YX. Alternative Pre-mRNA Splicing of the Mu Opioid Receptor Gene, OPRM1: Insight into Complex Mu Opioid Actions. Biomolecules 2021; 11:biom11101525. [PMID: 34680158 PMCID: PMC8534031 DOI: 10.3390/biom11101525] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/11/2021] [Accepted: 10/11/2021] [Indexed: 12/03/2022] Open
Abstract
Most opioid analgesics used clinically, including morphine and fentanyl, as well as the recreational drug heroin, act primarily through the mu opioid receptor, a class A Rhodopsin-like G protein-coupled receptor (GPCR). The single-copy mu opioid receptor gene, OPRM1, undergoes extensive alternative splicing, creating multiple splice variants or isoforms via a variety of alternative splicing events. These OPRM1 splice variants can be categorized into three major types based on the receptor structure: (1) full-length 7 transmembrane (TM) C-terminal variants; (2) truncated 6TM variants; and (3) single TM variants. Increasing evidence suggests that these OPRM1 splice variants are pharmacologically important in mediating the distinct actions of various mu opioids. More importantly, the OPRM1 variants can be targeted for development of novel opioid analgesics that are potent against multiple types of pain, but devoid of many side-effects associated with traditional opiates. In this review, we provide an overview of OPRM1 alternative splicing and its functional relevance in opioid pharmacology.
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Affiliation(s)
- Shan Liu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Wen-Jia Kang
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Anna Abrimian
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Jin Xu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Luca Cartegni
- Department of Chemical Biology, Ernest Mario School of Pharmacy Rutgers University, Piscataway, NJ 08854, USA;
| | - Susruta Majumdar
- Center for Clinical Pharmacology, University of Health Sciences & Pharmacy and Washington University School of Medicine, St. Louis, MO 63110, USA;
| | - Patrick Hesketh
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Alex Bekker
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Ying-Xian Pan
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
- Correspondence: ; Tel.: +1-973-972-3213
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