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Malard F, Wolter AC, Marquevielle J, Morvan E, Ecoutin A, Rüdisser S, Allain FT, Campagne S. The diversity of splicing modifiers acting on A-1 bulged 5'-splice sites reveals rules for rational drug design. Nucleic Acids Res 2024; 52:4124-4136. [PMID: 38554107 PMCID: PMC11077090 DOI: 10.1093/nar/gkae201] [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: 04/28/2023] [Revised: 12/07/2023] [Accepted: 03/07/2024] [Indexed: 04/01/2024] Open
Abstract
Pharmacological modulation of RNA splicing by small molecules is an emerging facet of drug discovery. In this context, the SMN2 splicing modifier SMN-C5 was used as a prototype to understand the mode of action of small molecule splicing modifiers and propose the concept of 5'-splice site bulge repair. In this study, we combined in vitro binding assays and structure determination by NMR spectroscopy to identify the binding modes of four other small molecule splicing modifiers that switch the splicing of either the SMN2 or the HTT gene. Here, we determined the solution structures of risdiplam, branaplam, SMN-CX and SMN-CY bound to the intermolecular RNA helix epitope containing an unpaired adenine within the G-2A-1G+1U+2 motif of the 5'-splice site. Despite notable differences in their scaffolds, risdiplam, SMN-CX, SMN-CY and branaplam contact the RNA epitope similarly to SMN-C5, suggesting that the 5'-splice site bulge repair mechanism can be generalised. These findings not only deepen our understanding of the chemical diversity of splicing modifiers that target A-1 bulged 5'-splice sites, but also identify common pharmacophores required for modulating 5'-splice site selection with small molecules.
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Affiliation(s)
- Florian Malard
- Université de Bordeaux, Inserm U1212, CNRS UMR5320, ARNA unit, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
- Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac Cedex, France
| | - Antje C Wolter
- ETH Zürich, Department of Biology, Institute of Biochemistry, Hönggerbergring 64, 8093 Zürich, Switzerland
| | - Julien Marquevielle
- Université de Bordeaux, Inserm U1212, CNRS UMR5320, ARNA unit, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
- Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac Cedex, France
| | - Estelle Morvan
- Institut Européen de Chimie et Biologie, UAR3033 CNRS, Université de Bordeaux, INSERM US01, Pessac 33600, France
| | - Agathe Ecoutin
- Université de Bordeaux, Inserm U1212, CNRS UMR5320, ARNA unit, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
- Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac Cedex, France
| | - Simon H Rüdisser
- ETH Zürich, Department of Biology, BioNMR platform, Hönggerbergring 64, 8093 Zürich, Switzerland
| | - Frédéric H T Allain
- ETH Zürich, Department of Biology, Institute of Biochemistry, Hönggerbergring 64, 8093 Zürich, Switzerland
| | - Sebastien Campagne
- Université de Bordeaux, Inserm U1212, CNRS UMR5320, ARNA unit, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
- Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac Cedex, France
- ETH Zürich, Department of Biology, Institute of Biochemistry, Hönggerbergring 64, 8093 Zürich, Switzerland
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2
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Qu Y, Bai J, Jiao H, Qi H, Huang W, OuYang S, Peng X, Jin Y, Wang H, Song F. Variants located in intron 6 of SMN1 lead to misdiagnosis in genetic detection and screening for SMA. Heliyon 2024; 10:e28015. [PMID: 38515714 PMCID: PMC10955315 DOI: 10.1016/j.heliyon.2024.e28015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 02/28/2024] [Accepted: 03/11/2024] [Indexed: 03/23/2024] Open
Abstract
Accurate genetic diagnosis is necessary for guiding the treatment of spinal muscular atrophy (SMA). An updated consensus for the diagnosis and management of SMA was published in 2018. However, clinicians should remain alert to some pitfalls of genetic testing that can occur when following a routine diagnosis. In this study, we report the diagnosis of three unrelated individuals who were initially misdiagnosed as carrying a homozygous deletion of SMN1 exon 7. MLPA (P060 and P021) and qPCR were used to detect the copy number of SMN. SMN1 variants were identified by SMN1 clone and next-generation sequencing (NGS). Transcription of SMN1 variants was detected using qRT-PCR and ex vivo splicing analysis. Among the three individuals, one was identified as a patient with SMA carrying a heterozygous deletion and a pathogenic variant (c.835-17_835-14delCTTT) of SMN1, one was a healthy carrier only carrying a heterozygous deletion of SMN1 exon 7, and the third was a patient with nemaline myopathy 2 carrying a heterozygous deletion of SMN1 exon 7. The misdiagnosis of these individuals was attributed to the presence of the c.835-17_835-14delCTTT or c.835-17C > G variants in SMN1 intron 6, which affect the amplification of SMN1 exon 7 during MLPA-P060 and qPCR testing. However, MLPA-P021 and NGS analyses were unaffected by these variants. These results support that additional detection methods should be employed in cases where the SMN1 copy number is ambiguous to minimize the misdiagnosis of SMA.
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Affiliation(s)
- Yujin Qu
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, China
| | - Jinli Bai
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, China
| | - Hui Jiao
- Department of Neurology, Children’s Hospital Affiliated to Capital Institute of Pediatrics, Beijing, China
| | - Hong Qi
- Prenatal Diagnosis Center, Beijing Haidian District Maternal and Child Health Care Hospital, Beijing, China
| | - Wenchen Huang
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, China
| | - Shijia OuYang
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, China
| | - Xiaoyin Peng
- Department of Neurology, Children’s Hospital Affiliated to Capital Institute of Pediatrics, Beijing, China
| | - Yuwei Jin
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, China
| | - Hong Wang
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, China
| | - Fang Song
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, China
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3
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Vorobeva MA, Skvortsov DA, Pervouchine DD. Cooperation and Competition of RNA Secondary Structure and RNA-Protein Interactions in the Regulation of Alternative Splicing. Acta Naturae 2023; 15:23-31. [PMID: 38234601 PMCID: PMC10790352 DOI: 10.32607/actanaturae.26826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 10/31/2023] [Indexed: 01/19/2024] Open
Abstract
The regulation of alternative splicing in eukaryotic cells is carried out through the coordinated action of a large number of factors, including RNA-binding proteins and RNA structure. The RNA structure influences alternative splicing by blocking cis-regulatory elements, or bringing them closer or farther apart. In combination with RNA-binding proteins, it generates transcript conformations that help to achieve the necessary splicing outcome. However, the binding of regulatory proteins depends on RNA structure and, vice versa, the formation of RNA structure depends on the interaction with regulators. Therefore, RNA structure and RNA-binding proteins are inseparable components of common regulatory mechanisms. This review highlights examples of alternative splicing regulation by RNA-binding proteins, the regulation through local and long-range RNA structures, as well as how these elements work together, cooperate, and compete.
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Affiliation(s)
- M. A. Vorobeva
- M.V. Lomonosov Moscow State University, Moscow, 119192 Russian Federation
| | - D. A. Skvortsov
- M.V. Lomonosov Moscow State University, Moscow, 119192 Russian Federation
| | - D. D. Pervouchine
- Skolkovo Institute of Science and Technology, Moscow, 121205 Russian Federation
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4
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Margasyuk S, Kalinina M, Petrova M, Skvortsov D, Cao C, Pervouchine DD. RNA in situ conformation sequencing reveals novel long-range RNA structures with impact on splicing. RNA (NEW YORK, N.Y.) 2023; 29:1423-1436. [PMID: 37295923 PMCID: PMC10573301 DOI: 10.1261/rna.079508.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 05/22/2023] [Indexed: 06/12/2023]
Abstract
Over recent years, long-range RNA structure has emerged as a factor that is fundamental to alternative splicing regulation. An increasing number of human disorders are now being associated with splicing defects; hence it is essential to develop methods that assess long-range RNA structure experimentally. RNA in situ conformation sequencing (RIC-seq) is a method that recapitulates RNA structure within physiological RNA-protein complexes. In this work, we juxtapose pairs of conserved complementary regions (PCCRs) that were predicted in silico with the results of RIC-seq experiments conducted in seven human cell lines. We show statistically that RIC-seq support of PCCRs correlates with their properties, such as equilibrium free energy, presence of compensatory substitutions, and occurrence of A-to-I RNA editing sites and forked eCLIP peaks. Exons enclosed in PCCRs that are supported by RIC-seq tend to have weaker splice sites and lower inclusion rates, which is indicative of post-transcriptional splicing regulation mediated by RNA structure. Based on these findings, we prioritize PCCRs according to their RIC-seq support and show, using antisense nucleotides and minigene mutagenesis, that PCCRs in two disease-associated human genes, PHF20L1 and CASK, and also PCCRs in their murine orthologs, impact alternative splicing. In sum, we demonstrate how RIC-seq experiments can be used to discover functional long-range RNA structures, and particularly those that regulate alternative splicing.
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Affiliation(s)
- Sergey Margasyuk
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
| | - Marina Kalinina
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
| | - Marina Petrova
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
| | - Dmitry Skvortsov
- Skolkovo Institute of Science and Technology, Moscow 143026, Russia
- Moscow State University, Faculty of Chemistry, Moscow 119991, Russia
| | - Changchang Cao
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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5
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Yalcintepe S, Karal Y, Demir S, Atli EI, Atli E, Eker D, Mail C, Zhuri D, Guler HS, Gurkan H. The Frequency of SMN1, SMN2 Copy Numbers in 246 Turkish Cases Analyzed with MLPA Method. Glob Med Genet 2023; 10:117-122. [PMID: 37332684 PMCID: PMC10275673 DOI: 10.1055/s-0043-1770055] [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] [Indexed: 06/20/2023] Open
Abstract
This study aimed to define the copy numbers of SMN1 and SMN2 genes and the diagnosis rate and carrier frequency of spinal muscular atrophy (SMA) in the Thrace region of Turkey. In this study, the frequency of deletions in exons 7 and 8 in the SMN1 gene and SMN2 copy numbers were investigated. A total of 133 cases with the preliminary diagnosis of SMA and 113 cases with the suspicion of being an SMA carrier from independent families were analyzed by multiplex ligation-dependent probe amplification method for SMN1 and SMN2 gene copy numbers. SMN1 homozygous deletions were detected in 34 patients (25.5%) of 133 cases with the suspicion of SMA. Cases diagnosed with SMA type I was 41.17% (14/34), 29.4% (10/34) with type II, 26.4% (9/34) with type III, and 2.94% (1/34) with type IV. The SMA carrier rate was 46.01% in 113 cases. In 34 SMA cases, SMN2 copy numbers were: two copies - 28 cases (82.3%), three copies - 6 cases (17.6%). SMN2 homozygous deletions were detected in 15% (17/113) of carrier analysis cases. The consanguinity rate of the parents was 23.5% in SMA diagnosed cases. In this study, we had a 25.5% of SMA diagnosis rate and 46% SMA carrier frequency. The current study also showed the relatively low consanguinity rate of the Thrace region, with 23.5% according to the east of Turkey.
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Affiliation(s)
- Sinem Yalcintepe
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Yasemin Karal
- Department of Pediatric Neurology, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Selma Demir
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Emine Ikbal Atli
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Engin Atli
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Damla Eker
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Cisem Mail
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Drenushe Zhuri
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Hazal Sezginer Guler
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Hakan Gurkan
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
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6
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Lazo PA, Morejón-García P. VRK1 variants at the cross road of Cajal body neuropathogenic mechanisms in distal neuropathies and motor neuron diseases. Neurobiol Dis 2023; 183:106172. [PMID: 37257665 DOI: 10.1016/j.nbd.2023.106172] [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: 03/24/2023] [Revised: 05/09/2023] [Accepted: 05/24/2023] [Indexed: 06/02/2023] Open
Abstract
Distal hereditary neuropathies and neuro motor diseases are complex neurological phenotypes associated with pathogenic variants in a large number of genes, but in some the origin is unknown. Recently, rare pathogenic variants of the human VRK1 gene have been associated with these neurological phenotypes. All VRK1 pathogenic variants are recessive, and their clinical presentation occurs in either homozygous or compound heterozygous patients. The pathogenic VRK1 gene pathogenic variants are located in three clusters within the protein sequence. The main, and initial, shared clinical phenotype among VRK1 pathogenic variants is a distal progressive loss of motor and/or sensory function, which includes diseases such as spinal muscular atrophy, Charcot-Marie-Tooth, amyotrophic lateral sclerosis and hereditary spastic paraplegia. In most cases, symptoms start early in infancy, or in utero, and are slowly progressive. Additional neurological symptoms vary among non-related patients, probably because of their different VRK1 variants and their genetic background. The underlying common pathogenic mechanism, by its functional impairment, is a likely consequence of the roles that the VRK1 protein plays in the regulation on the stability and assembly of Cajal bodies, which affect RNA maturation and processing, neuronal migration of RNPs along axons, and DNA-damage responses. Alterations of these processes are associated with several neuro sensory or motor syndromes. The clinical heterogeneity of the neurological phenotypes associated with VRK1 is a likely consequence of the protein complexes in which VRK1 is integrated, which include several proteins known to be associated with Cajal bodies and DNA damage responses. Several hereditary distal neurological diseases are a consequence of pathogenic variants in genes that alter these cellular functions. We conclude that VRK1-related distal hereditary neuropathies and motor neuron diseases represent a novel subgroup of Cajal body related neurological syndromes.
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Affiliation(s)
- Pedro A Lazo
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, Salamanca, Spain.
| | - Patricia Morejón-García
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, Salamanca, Spain.
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7
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Rogalska ME, Vivori C, Valcárcel J. Regulation of pre-mRNA splicing: roles in physiology and disease, and therapeutic prospects. Nat Rev Genet 2023; 24:251-269. [PMID: 36526860 DOI: 10.1038/s41576-022-00556-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2022] [Indexed: 12/23/2022]
Abstract
The removal of introns from mRNA precursors and its regulation by alternative splicing are key for eukaryotic gene expression and cellular function, as evidenced by the numerous pathologies induced or modified by splicing alterations. Major recent advances have been made in understanding the structures and functions of the splicing machinery, in the description and classification of physiological and pathological isoforms and in the development of the first therapies for genetic diseases based on modulation of splicing. Here, we review this progress and discuss important remaining challenges, including predicting splice sites from genomic sequences, understanding the variety of molecular mechanisms and logic of splicing regulation, and harnessing this knowledge for probing gene function and disease aetiology and for the design of novel therapeutic approaches.
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Affiliation(s)
- Malgorzata Ewa Rogalska
- Genome Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Claudia Vivori
- Genome Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain
- The Francis Crick Institute, London, UK
| | - Juan Valcárcel
- Genome Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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8
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Ross CJ, Ulitsky I. Discovering functional motifs in long noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2022; 13:e1708. [PMID: 34981665 DOI: 10.1002/wrna.1708] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/19/2021] [Accepted: 12/04/2021] [Indexed: 12/27/2022]
Abstract
Long noncoding RNAs (lncRNAs) are products of pervasive transcription that closely resemble messenger RNAs on the molecular level, yet function through largely unknown modes of action. The current model is that the function of lncRNAs often relies on specific, typically short, conserved elements, connected by linkers in which specific sequences and/or structures are less important. This notion has fueled the development of both computational and experimental methods focused on the discovery of functional elements within lncRNA genes, based on diverse signals such as evolutionary conservation, predicted structural elements, or the ability to rescue loss-of-function phenotypes. In this review, we outline the main challenges that the different methods need to overcome, describe the recently developed approaches, and discuss their respective limitations. This article is categorized under: RNA Evolution and Genomics > Computational Analyses of RNA RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.
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Affiliation(s)
- Caroline Jane Ross
- Biological Regulation and Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Igor Ulitsky
- Biological Regulation and Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
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9
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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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10
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Kumar R, Haider S. Protein network analysis to prioritize key genes in amyotrophic lateral sclerosis. IBRO Neurosci Rep 2021; 12:25-44. [PMID: 34918006 PMCID: PMC8669318 DOI: 10.1016/j.ibneur.2021.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/18/2021] [Accepted: 12/05/2021] [Indexed: 12/18/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a fatal disease, progressive nature characterizes by loss of both upper and lower motor neuron functions. One of the major challenge is to understand the mechanism of ALS multifactorial nature. We aimed to explore some key genes related to ALS through bioinformatics methods for its therapeutic intervention. Here, we applied a systems biology approach involving experimentally validated 148 ALS-associated proteins and construct ALS protein-protein interaction network (ALS-PPIN). The network was further statistically analysed and identified bottleneck-hubs. The network is also subjected to identify modules which could have similar functions. The interaction between the modules and bottleneck-hubs provides the functional regulatory role of the ALS mechanism. The ALS-PPIN demonstrated a hierarchical scale-free nature. We identified 17 bottleneck-hubs, in which CDC5L, SNW1, TP53, SOD1, and VCP were the high degree nodes (hubs) in ALS-PPIN. CDC5L was found to control highly cluster modules and play a vital role in the stability of the overall network followed by SNW1, TP53, SOD1, and VCP. HSPA5 and HSPA8 acting as a common connector for CDC5L and TP53 bottleneck-hubs. The functional and disease association analysis showed ALS has a strong correlation with mRNA processing, protein deubiquitination, and neoplasms, nervous system, immune system disease classes. In the future, biochemical investigation of the observed bottleneck-hubs and their interacting partners could provide a further understanding of their role in the pathophysiology of ALS. Amyotrophic Lateral Sclerosis protein-protein interaction network (ALS-PPIN) followed a hierarchical scale-free nature. We identified 17 bottleneck-hubs in the ALS-PPIN. Among bottleneck-hubs we found CDC5L, SNW1, TP53, SOD1, and VCP were the high degree nodes (hubs) in the ALS-PPIN. CDC5L is the effective communicator with all five modules in the ALS-PPIN and followed by SNW1 and TP53. Modules are highly associated with various disease classes like neoplasms, nervous systems and others.
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Key Words
- ALS
- ALS, Amyotrophic Lateral Sclerosis
- ALS-PPIN
- ALS-PPIN, Amyotrophic Lateral Sclerosis Protein-Protein Interaction Network
- ALSoD, Amyotrophic Lateral Sclerosis online database
- BC, Betweenness centrality
- Bn-H, Bottleneck-hub
- Bottleneck-hubs
- CDC5L
- CDC5L, Cell division cycle5-likeprotein
- FUS, Fused in sarcoma
- MCODE, Molecular Complex Detection
- MND, Motor neuron disease
- SMA, Spinal muscular atrophy
- SMN, Survival of motor neuron
- SNW1
- SNW1, SNW domain-containing protein 1
- SOD1
- SOD1, Superoxide dismutase
- TP53
- TP53, Tumor protein p53
- VCP
- VCP, Valosin containing protein
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Affiliation(s)
- Rupesh Kumar
- Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Sec-62, Uttar Pradesh, India
| | - Shazia Haider
- Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Sec-62, Uttar Pradesh, India
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11
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Alternative Splicing Role in New Therapies of Spinal Muscular Atrophy. Genes (Basel) 2021; 12:genes12091346. [PMID: 34573328 PMCID: PMC8468182 DOI: 10.3390/genes12091346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/17/2022] Open
Abstract
It has been estimated that 80% of the pre-mRNA undergoes alternative splicing, which exponentially increases the flow of biological information in cellular processes and can be an attractive therapeutic target. It is a crucial mechanism to increase genetic diversity. Disturbed alternative splicing is observed in many disorders, including neuromuscular diseases and carcinomas. Spinal Muscular Atrophy (SMA) is an autosomal recessive neurodegenerative disease. Homozygous deletion in 5q13 (the region coding for the motor neuron survival gene (SMN1)) is responsible for 95% of SMA cases. The nearly identical SMN2 gene does not compensate for SMN loss caused by SMN1 gene mutation due to different splicing of exon 7. A pathologically low level of survival motor neuron protein (SMN) causes degeneration of the anterior horn cells in the spinal cord with associated destruction of α-motor cells and manifested by muscle weakness and loss. Understanding the regulation of the SMN2 pre-mRNA splicing process has allowed for innovative treatment and the introduction of new medicines for SMA. After describing the concept of splicing modulation, this review will cover the progress achieved in this field, by highlighting the breakthrough accomplished recently for the treatment of SMA using the mechanism of alternative splicing.
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12
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Ottesen EW, Luo D, Singh NN, Singh RN. High Concentration of an ISS-N1-Targeting Antisense Oligonucleotide Causes Massive Perturbation of the Transcriptome. Int J Mol Sci 2021; 22:ijms22168378. [PMID: 34445083 PMCID: PMC8395096 DOI: 10.3390/ijms22168378] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/14/2021] [Accepted: 07/31/2021] [Indexed: 12/17/2022] Open
Abstract
Intronic splicing silencer N1 (ISS-N1) located within Survival Motor Neuron 2 (SMN2) intron 7 is the target of a therapeutic antisense oligonucleotide (ASO), nusinersen (Spinraza), which is currently being used for the treatment of spinal muscular atrophy (SMA), a leading genetic disease associated with infant mortality. The discovery of ISS-N1 as a promising therapeutic target was enabled in part by Anti-N1, a 20-mer ASO that restored SMN2 exon 7 inclusion by annealing to ISS-N1. Here, we analyzed the transcriptome of SMA patient cells treated with 100 nM of Anti-N1 for 30 h. Such concentrations are routinely used to demonstrate the efficacy of an ASO. While 100 nM of Anti-N1 substantially stimulated SMN2 exon 7 inclusion, it also caused massive perturbations in the transcriptome and triggered widespread aberrant splicing, affecting expression of essential genes associated with multiple cellular processes such as transcription, splicing, translation, cell signaling, cell cycle, macromolecular trafficking, cytoskeletal dynamics, and innate immunity. We validated our findings with quantitative and semiquantitative PCR of 39 candidate genes associated with diverse pathways. We also showed a substantial reduction in off-target effects with shorter ISS-N1-targeting ASOs. Our findings are significant for implementing better ASO design and dosing regimens of ASO-based drugs.
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Conserved long-range base pairings are associated with pre-mRNA processing of human genes. Nat Commun 2021; 12:2300. [PMID: 33863890 PMCID: PMC8052449 DOI: 10.1038/s41467-021-22549-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 03/20/2021] [Indexed: 02/07/2023] Open
Abstract
The ability of nucleic acids to form double-stranded structures is essential for all living systems on Earth. Current knowledge on functional RNA structures is focused on locally-occurring base pairs. However, crosslinking and proximity ligation experiments demonstrated that long-range RNA structures are highly abundant. Here, we present the most complete to-date catalog of conserved complementary regions (PCCRs) in human protein-coding genes. PCCRs tend to occur within introns, suppress intervening exons, and obstruct cryptic and inactive splice sites. Double-stranded structure of PCCRs is supported by decreased icSHAPE nucleotide accessibility, high abundance of RNA editing sites, and frequent occurrence of forked eCLIP peaks. Introns with PCCRs show a distinct splicing pattern in response to RNAPII slowdown suggesting that splicing is widely affected by co-transcriptional RNA folding. The enrichment of 3'-ends within PCCRs raises the intriguing hypothesis that coupling between RNA folding and splicing could mediate co-transcriptional suppression of premature pre-mRNA cleavage and polyadenylation.
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14
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Mucke HAM. Drug Repurposing Patent Applications October-December 2020. Assay Drug Dev Technol 2021; 19:209-214. [PMID: 33605782 DOI: 10.1089/adt.2021.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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15
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Spinal muscular atrophy: Broad disease spectrum and sex-specific phenotypes. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166063. [PMID: 33412266 DOI: 10.1016/j.bbadis.2020.166063] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/14/2020] [Accepted: 12/21/2020] [Indexed: 12/17/2022]
Abstract
Spinal muscular atrophy (SMA) is one of the major genetic disorders associated with infant mortality. More than 90% of cases of SMA result from deletions of or mutations in the Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, does not compensate for the loss of SMN1 due to predominant skipping of exon 7. The spectrum of SMA is broad, ranging from prenatal death to infant mortality to survival into adulthood. All tissues, including brain, spinal cord, bone, skeletal muscle, heart, lung, liver, pancreas, gastrointestinal tract, kidney, spleen, ovary and testis, are directly and/or indirectly affected in SMA. Accumulating evidence on impaired mitochondrial biogenesis and defects in X chromosome-linked modifying factors, coupled with the sexual dimorphic nature of many tissues, point to sex-specific vulnerabilities in SMA. Here we review the role of sex in the pathogenesis of SMA.
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Vu-Han TL, Weiß C, Pumberger M. Novel therapies for spinal muscular atrophy are likely changing the patient phenotype. Spine J 2020; 20:1893-1898. [PMID: 32858169 DOI: 10.1016/j.spinee.2020.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/21/2020] [Accepted: 08/23/2020] [Indexed: 02/03/2023]
Affiliation(s)
- Tu-Lan Vu-Han
- Center for Musculoskeletal Surgery Berlin Mitte; Charité University Medicine Berlin, Charitéplatz 1, Berlin 10117, Germany.
| | - Claudia Weiß
- Center for chronically sick children, Department of Neuropediatrics; Charité University, Medicine Berlin, Augustenburger Platz 1, Berlin 13353, Germany
| | - Matthias Pumberger
- Center for Musculoskeletal Surgery Berlin Mitte; Charité University Medicine Berlin, Charitéplatz 1, Berlin 10117, Germany
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Singh RN, Ottesen EW, Singh NN. The First Orally Deliverable Small Molecule for the Treatment of Spinal Muscular Atrophy. Neurosci Insights 2020; 15:2633105520973985. [PMID: 33283185 PMCID: PMC7691903 DOI: 10.1177/2633105520973985] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 10/27/2020] [Indexed: 12/12/2022] Open
Abstract
Spinal muscular atrophy (SMA) is 1 of the leading causes of infant mortality. SMA
is mostly caused by low levels of Survival Motor Neuron (SMN) protein due to
deletion of or mutation in the SMN1 gene. Its nearly identical
copy, SMN2, fails to compensate for the loss of
SMN1 due to predominant skipping of exon 7. Correction of
SMN2 exon 7 splicing by an antisense oligonucleotide (ASO),
nusinersen (Spinraza™), that targets the intronic splicing silencer N1 (ISS-N1)
became the first approved therapy for SMA. Restoration of SMN levels using gene
therapy was the next. Very recently, an orally deliverable small molecule,
risdiplam (Evrysdi™), became the third approved therapy for SMA. Here we discuss
how these therapies are positioned to meet the needs of the broad phenotypic
spectrum of SMA patients.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
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Ando S, Suzuki S, Okubo S, Ohuchi K, Takahashi K, Nakamura S, Shimazawa M, Fuji K, Hara H. Discovery of a CNS penetrant small molecule SMN2 splicing modulator with improved tolerability for spinal muscular atrophy. Sci Rep 2020; 10:17472. [PMID: 33060681 PMCID: PMC7562719 DOI: 10.1038/s41598-020-74346-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 09/28/2020] [Indexed: 01/08/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease, typically resulting from loss-of-function mutations in the survival motor neuron 1 (SMN1) gene. Nusinersen/SPINRAZA, a splice-switching oligonucleotide that modulates SMN2 (a paralog of SMN1) splicing and consequently increases SMN protein levels, has a therapeutic effect for SMA. Previously reported small-molecule SMN2 splicing modulators such as risdiplam/EVRYSDI and its analog SMN-C3 modulate not only the splicing of SMN2 but also that of secondary splice targets, including forkhead box protein M1 (FOXM1). Through screening SMA patient-derived fibroblasts, a novel small molecule, designated TEC-1, was identified that selectively modulates SMN2 splicing over three secondary splice targets. TEC-1 did not strongly affect the splicing of FOXM1, and unlike risdiplam, did not induce micronucleus formation. In addition, TEC-1 showed higher selectively on galactosylceramidase and huntingtin gene expression compared to previously reported compounds (e.g., SMN-C3) due to off-target effects on cryptic exon inclusion and nonsense-mediated mRNA decay. Moreover, TEC-1 significantly ameliorated the disease phenotype in an SMA murine model in vivo. Thus, TEC-1 may have promising therapeutic potential for SMA, and our study demonstrates the feasibility of RNA-targeting small-molecule drug development with an improved tolerability profile.
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Affiliation(s)
- Shiori Ando
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | | | | | - Kazuki Ohuchi
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Kei Takahashi
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Shinsuke Nakamura
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Masamitsu Shimazawa
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan
| | - Koji Fuji
- Reborna Biosciences Inc., Kanagawa, 251-0012, Japan
| | - Hideaki Hara
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, 501-1196, Japan.
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Ottesen EW, Singh RN. Characteristics of circular RNAs generated by human Survival Motor Neuron genes. Cell Signal 2020; 73:109696. [PMID: 32553550 PMCID: PMC7387165 DOI: 10.1016/j.cellsig.2020.109696] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023]
Abstract
Circular RNAs (circRNAs) belong to a diverse class of stable RNAs expressed in all cell types. Their proposed functions include sponging of microRNAs (miRNAs), sequestration and trafficking of proteins, assembly of multimeric complexes, production of peptides, and regulation of transcription. Backsplicing due to RNA structures formed by an exceptionally high number of Alu repeats lead to the production of a vast repertoire of circRNAs by human Survival Motor Neuron genes, SMN1 and SMN2, that code for SMN, an essential multifunctional protein. Low levels of SMN due to deletion or mutation of SMN1 result in spinal muscular atrophy (SMA), a major genetic disease of infants and children. Mild SMA is also recorded in adult population, expanding the spectrum of the disease. Here we review SMN circRNAs with respect to their biogenesis, sequence features, and potential functions. We also discuss how SMN circRNAs could be exploited for diagnostic and therapeutic purposes.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America.
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Singh NN, Ottesen EW, Singh RN. A survey of transcripts generated by spinal muscular atrophy genes. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2020; 1863:194562. [PMID: 32387331 PMCID: PMC7302838 DOI: 10.1016/j.bbagrm.2020.194562] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/01/2020] [Accepted: 04/13/2020] [Indexed: 02/07/2023]
Abstract
Human Survival Motor Neuron (SMN) genes code for SMN, an essential multifunctional protein. Complete loss of SMN is embryonic lethal, while low levels of SMN lead to spinal muscular atrophy (SMA), a major genetic disease of children and infants. Reduced levels of SMN are associated with the abnormal development of heart, lung, muscle, gastro-intestinal system and testis. The SMN loci have been shown to generate a vast repertoire of transcripts, including linear, back- and trans-spliced RNAs as well as antisense long noncoding RNAs. However, functions of the majority of these transcripts remain unknown. Here we review the nature of RNAs generated from the SMN loci and discuss their potential functions in cellular metabolism.
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Affiliation(s)
- Natalia N Singh
- Department of Biomedical Science, Iowa State University, Ames, IA, 50011, United States of America
| | - Eric W Ottesen
- Department of Biomedical Science, Iowa State University, Ames, IA, 50011, United States of America
| | - Ravindra N Singh
- Department of Biomedical Science, Iowa State University, Ames, IA, 50011, United States of America.
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Taylor K, Sobczak K. Intrinsic Regulatory Role of RNA Structural Arrangement in Alternative Splicing Control. Int J Mol Sci 2020; 21:ijms21145161. [PMID: 32708277 PMCID: PMC7404189 DOI: 10.3390/ijms21145161] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 07/17/2020] [Indexed: 12/14/2022] Open
Abstract
Alternative splicing is a highly sophisticated process, playing a significant role in posttranscriptional gene expression and underlying the diversity and complexity of organisms. Its regulation is multilayered, including an intrinsic role of RNA structural arrangement which undergoes time- and tissue-specific alterations. In this review, we describe the principles of RNA structural arrangement and briefly decipher its cis- and trans-acting cellular modulators which serve as crucial determinants of biological functionality of the RNA structure. Subsequently, we engage in a discussion about the RNA structure-mediated mechanisms of alternative splicing regulation. On one hand, the impairment of formation of optimal RNA structures may have critical consequences for the splicing outcome and further contribute to understanding the pathomechanism of severe disorders. On the other hand, the structural aspects of RNA became significant features taken into consideration in the endeavor of finding potential therapeutic treatments. Both aspects have been addressed by us emphasizing the importance of ongoing studies in both fields.
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Singh RN, Seo J, Singh NN. RNA in spinal muscular atrophy: therapeutic implications of targeting. Expert Opin Ther Targets 2020; 24:731-743. [PMID: 32538213 DOI: 10.1080/14728222.2020.1783241] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Spinal muscular atrophy (SMA) is caused by low levels of the Survival Motor Neuron (SMN) protein due to deletions of or mutations in the SMN1 gene. Humans carry another nearly identical gene, SMN2, which mostly produces a truncated and less stable protein SMNΔ7 due to predominant skipping of exon 7. Elevation of SMN upon correction of SMN2 exon 7 splicing and gene therapy have been proven to be the effective treatment strategies for SMA. AREAS COVERED This review summarizes existing and potential SMA therapies that are based on RNA targeting.We also discuss the mechanistic basis of RNA-targeting molecules. EXPERT OPINION The discovery of intronic splicing silencer N1 (ISS-N1) was the first major step towards developing the currently approved antisense-oligonucleotide (ASO)-directed therapy (SpinrazaTM) based on the correction of exon 7 splicing of the endogenous SMN2pre-mRNA. Recently, gene therapy (Zolgensma) has become the second approved treatment for SMA. Small compounds (currently in clinical trials) capable of restoring SMN2 exon 7 inclusion further expand the class of the RNA targeting molecules for SMA therapy. Endogenous RNA targets, such as long non-coding RNAs, circular RNAs, microRNAs and ribonucleoproteins, could be potentially exploited for developing additional SMA therapies.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University , Ames, IA, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University , Ames, IA, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University , Ames, IA, USA
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Baralle FE, Singh RN, Stamm S. RNA structure and splicing regulation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194448. [PMID: 31730825 DOI: 10.1016/j.bbagrm.2019.194448] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Francisco E Baralle
- Italian Liver Disease Foundation (FIF), Building Q AREA Science Park, Basovizza Campus ss14, Km 163,5, 34149 Trieste, Italy
| | - Ravindra N Singh
- Iowa State University, Department of Biomedical Science, 2034 Veterinary Medicine, Ames, IA 50011, United States.
| | - Stefan Stamm
- University of Kentucky, Department of Molecular and Cellular Biochemistry, College of Medicine, B159 Biomedical Biological Sciences Research Bldg. 741 South Limestone, Lexington, KY 40536, United States
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More is needed to complement the available therapies of spinal muscular atrophy. Future Med Chem 2019; 11:2873-2876. [PMID: 31668092 DOI: 10.4155/fmc-2019-0239] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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