1
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Leckie J, Yokota T. Potential of Cell-Penetrating Peptide-Conjugated Antisense Oligonucleotides for the Treatment of SMA. Molecules 2024; 29:2658. [PMID: 38893532 PMCID: PMC11173757 DOI: 10.3390/molecules29112658] [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: 05/06/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
Spinal muscular atrophy (SMA) is a severe neuromuscular disorder that is caused by mutations in the survival motor neuron 1 (SMN1) gene, hindering the production of functional survival motor neuron (SMN) proteins. Antisense oligonucleotides (ASOs), a versatile DNA-like drug, are adept at binding to target RNA to prevent translation or promote alternative splicing. Nusinersen is an FDA-approved ASO for the treatment of SMA. It effectively promotes alternative splicing in pre-mRNA transcribed from the SMN2 gene, an analog of the SMN1 gene, to produce a greater amount of full-length SMN protein, to compensate for the loss of functional protein translated from SMN1. Despite its efficacy in ameliorating SMA symptoms, the cellular uptake of these ASOs is suboptimal, and their inability to penetrate the CNS necessitates invasive lumbar punctures. Cell-penetrating peptides (CPPs), which can be conjugated to ASOs, represent a promising approach to improve the efficiency of these treatments for SMA and have the potential to transverse the blood-brain barrier to circumvent the need for intrusive intrathecal injections and their associated adverse effects. This review provides a comprehensive analysis of ASO therapies, their application for the treatment of SMA, and the encouraging potential of CPPs as delivery systems to improve ASO uptake and overall efficiency.
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Affiliation(s)
- Jamie Leckie
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Toshifumi Yokota
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Friends of Garrett Cumming Research & Muscular Dystrophy Canada HM Toupin Neurological Sciences Research, Edmonton, AB T6G 2H7, Canada
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2
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Zhang L, Xie X, Djokovic N, Nikolic K, Kosenkov D, Abendroth F, Vázquez O. Reversible Control of RNA Splicing by Photoswitchable Small Molecules. J Am Chem Soc 2023. [PMID: 37276581 DOI: 10.1021/jacs.3c03275] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dynamics are intrinsic to both RNA function and structure. Yet, the available means to precisely provide RNA-based processes with spatiotemporal resolution are scarce. Here, our work pioneers a reversible approach to regulate RNA splicing within primary patient-derived cells by synthetic photoswitches. Our small molecule enables conditional real-time control at mRNA and protein levels. NMR experiments, together with theoretical calculations, photochemical characterization, fluorescence polarization measurements, and living cell-based assays, confirmed light-dependent exon inclusion as well as an increase in the target functional protein. Therefore, we first demonstrated the potential of photopharmacology modulation in splicing, tweaking the current optochemical toolkit. The timeliness on the consolidation of RNA research as the driving force toward therapeutical innovation holds the promise that our approach will contribute to redrawing the vision of RNA.
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Affiliation(s)
- Lei Zhang
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
| | - Xiulan Xie
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
| | - Nemanja Djokovic
- Department of Pharmaceutical Chemistry, University of Belgrade, Belgrade, 11000, Serbia
| | - Katarina Nikolic
- Department of Pharmaceutical Chemistry, University of Belgrade, Belgrade, 11000, Serbia
| | - Dmitri Kosenkov
- Department of Chemistry and Physics, Monmouth University, West Long Branch, New Jersey 07764, United States
| | - Frank Abendroth
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
| | - Olalla Vázquez
- Department of Chemistry, University of Marburg, Marburg, D-35043, Germany
- Center for Synthetic Microbiology (SYNMIKRO), University of Marburg, Marburg, D-35043, Germany
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3
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Sabuncu Gürses G, Erdem SS, Saçan MT. A QSAR study to predict the survival motor neuron promoter activity of candidate diaminoquinazoline derivatives for the potential treatment of spinal muscular atrophy. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2023; 34:247-266. [PMID: 37125536 DOI: 10.1080/1062936x.2023.2200975] [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: 05/03/2023]
Abstract
Spinal Muscular Atrophy is a genetic neuromuscular disease that leads to muscle weakness and atrophy and it is characterized by the loss of α-motor neurons in the spinal cord's anterior horn cells. The disease appears due to low levels of the survival motor neuron protein. There are continuing clinical trials for the treatment of Spinal Muscular Atrophy. Quinazoline-based compounds are promising since they were tested on fibroblasts derived from the patients and found to increase the survival motor neuron protein levels. In this study, using multiple linear regression, we generated robust and valid quantitative structure- activity relationship models to predict the survival motor neuron-2 promoter activity of the new candidate compounds using the experimental survival motor neuron-2 promoter activity values of 2,4-diaminoquinazoline derivatives taken from the literature. The novel compounds designed by combining the pyrido[1,2-α]pyrimidin-4-one moeity of the known drug Risdiplam with that of 2,4 - diaminoquinazoline scaffold were predicted to exhibit strong promoter activities.
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Affiliation(s)
- G Sabuncu Gürses
- Chemistry Department, Faculty of Science, Marmara University, Istanbul, Turkey
| | - S S Erdem
- Chemistry Department, Faculty of Science, Marmara University, Istanbul, Turkey
| | - M T Saçan
- Institute of Environmental Sciences, Bogaziçi University, Istanbul, Turkey
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4
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Adami R, Bottai D. NSC Physiological Features in Spinal Muscular Atrophy: SMN Deficiency Effects on Neurogenesis. Int J Mol Sci 2022; 23:ijms232315209. [PMID: 36499528 PMCID: PMC9736802 DOI: 10.3390/ijms232315209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 11/20/2022] [Accepted: 11/30/2022] [Indexed: 12/08/2022] Open
Abstract
While the U.S. Food and Drug Administration and the European Medicines Evaluation Agency have recently approved new drugs to treat spinal muscular atrophy 1 (SMA1) in young patients, they are mostly ineffective in older patients since many motor neurons have already been lost. Therefore, understanding nervous system (NS) physiology in SMA patients is essential. Consequently, studying neural stem cells (NSCs) from SMA patients is of significant interest in searching for new treatment targets that will enable researchers to identify new pharmacological approaches. However, studying NSCs in these patients is challenging since their isolation damages the NS, making it impossible with living patients. Nevertheless, it is possible to study NSCs from animal models or create them by differentiating induced pluripotent stem cells obtained from SMA patient peripheral tissues. On the other hand, therapeutic interventions such as NSCs transplantation could ameliorate SMA condition. This review summarizes current knowledge on the physiological properties of NSCs from animals and human cellular models with an SMA background converging on the molecular and neuronal circuit formation alterations of SMA fetuses and is not focused on the treatment of SMA. By understanding how SMA alters NSC physiology, we can identify new and promising interventions that could help support affected patients.
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5
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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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6
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Evaluation of carboxyfluorescein-labeled 7-methylguanine nucleotides as probes for studying cap-binding proteins by fluorescence anisotropy. Sci Rep 2021; 11:7687. [PMID: 33833335 PMCID: PMC8032668 DOI: 10.1038/s41598-021-87306-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/26/2021] [Indexed: 11/17/2022] Open
Abstract
Fluorescence anisotropy (FA) is a powerful technique for the discovery of protein inhibitors in a high-throughput manner. In this study, we sought to develop new universal FA-based assays for the evaluation of compounds targeting mRNA 5′ cap-binding proteins of therapeutic interest, including eukaryotic translation initiation factor 4E and scavenger decapping enzyme. For this purpose, a library of 19 carboxyfluorescein probes based on 7-methylguanine nucleotides was evaluated as FA probes for these proteins. Optimal probe:protein systems were further investigated in competitive binding experiments and adapted for high-throughput screening. Using a small in-house library of compounds, we verified and confirmed the accuracy of the developed FA assay to study cap-binding protein binders. The applications of the most promising probes were then extended to include evaluation of allosteric inhibitors as well as RNA ligands. From this analysis, we confirmed the utility of the method to study small molecule ligands and evaluate differently 5′ capped RNAs.
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7
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Singh M, Singh SP, Yadav D, Agarwal M, Agarwal S, Agarwal V, Swargiary G, Srivastava S, Tyagi S, Kaur R, Mani S. Targeted Delivery for Neurodegenerative Disorders Using Gene Therapy Vectors: Gene Next Therapeutic Goals. Curr Gene Ther 2021; 21:23-42. [PMID: 32811395 DOI: 10.2174/1566523220999200817164907] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 11/22/2022]
Abstract
The technique of gene therapy, ever since its advent nearly fifty years ago, has been utilized by scientists as a potential treatment option for various disorders. This review discusses some of the major neurodegenerative diseases (NDDs) like Alzheimer's disease (AD), Parkinson's Disease (PD), Motor neuron diseases (MND), Spinal Muscular Atrophy (SMA), Huntington's Disease (HD), Multiple Sclerosis (MS), etc. and their underlying genetic mechanisms along with the role that gene therapy can play in combating them. The pathogenesis and the molecular mechanisms specifying the altered gene expression of each of these NDDs have also been discussed in elaboration. The use of gene therapy vectors can prove to be an effective tool in the field of curative modern medicine for the generations to come. Therefore, consistent efforts and progressive research towards its implementation can provide us with powerful treatment options for disease conditions that have so far been considered as incurable.
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Affiliation(s)
- Manisha Singh
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P, India
| | - Surinder P Singh
- Bhartiya Nirdeshak Dravya Division, CSIR-National Physical Laboratory, New Delhi, India
| | - Deepshikha Yadav
- Bhartiya Nirdeshak Dravya Division, CSIR-National Physical Laboratory, New Delhi, India
| | - Mugdha Agarwal
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P., India
| | - Shriya Agarwal
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P., India
| | - Vinayak Agarwal
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P., India
| | - Geeta Swargiary
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P., India
| | - Sahil Srivastava
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P., India
| | - Sakshi Tyagi
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P., India
| | - Ramneek Kaur
- School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Shalini Mani
- Department of Biotechnology, Jaypee Institute of Information Technology (JIIT) Noida, U.P., India
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8
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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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9
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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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10
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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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11
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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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12
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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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13
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Ottesen EW, Luo D, Seo J, Singh NN, Singh RN. Human Survival Motor Neuron genes generate a vast repertoire of circular RNAs. Nucleic Acids Res 2019; 47:2884-2905. [PMID: 30698797 PMCID: PMC6451121 DOI: 10.1093/nar/gkz034] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 01/08/2019] [Accepted: 01/14/2019] [Indexed: 12/12/2022] Open
Abstract
Circular RNAs (circRNAs) perform diverse functions, including the regulation of transcription, translation, peptide synthesis, macromolecular sequestration and trafficking. Inverted Alu repeats capable of forming RNA:RNA duplexes that bring splice sites together for backsplicing are known to facilitate circRNA generation. However, higher limits of circRNAs produced by a single Alu-rich gene are currently not predictable due to limitations of amplification and analyses. Here, using a tailored approach, we report a surprising diversity of exon-containing circRNAs generated by the Alu-rich Survival Motor Neuron (SMN) genes that code for SMN, an essential multifunctional protein in humans. We show that expression of the vast repertoire of SMN circRNAs is universal. Several of the identified circRNAs harbor novel exons derived from both intronic and intergenic sequences. A comparison with mouse Smn circRNAs underscored a clear impact of primate-specific Alu elements on shaping the overall repertoire of human SMN circRNAs. We show the role of DHX9, an RNA helicase, in splicing regulation of several SMN exons that are preferentially incorporated into circRNAs. Our results suggest self- and cross-regulation of biogenesis of various SMN circRNAs. These findings bring a novel perspective towards a better understanding of SMN gene function.
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Affiliation(s)
- Eric W Ottesen
- Iowa State University, Biomedical Sciences, Ames, IA 50011, USA
| | - Diou Luo
- Iowa State University, Biomedical Sciences, Ames, IA 50011, USA
| | - Joonbae Seo
- Iowa State University, Biomedical Sciences, Ames, IA 50011, USA
| | - Natalia N Singh
- Iowa State University, Biomedical Sciences, Ames, IA 50011, USA
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14
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Ottesen EW, Singh NN, Luo D, Singh RN. High-affinity RNA targets of the Survival Motor Neuron protein reveal diverse preferences for sequence and structural motifs. Nucleic Acids Res 2019; 46:10983-11001. [PMID: 30165668 PMCID: PMC6237763 DOI: 10.1093/nar/gky770] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 08/24/2018] [Indexed: 12/23/2022] Open
Abstract
The Survival Motor Neuron (SMN) protein is essential for survival of all animal cells. SMN harbors a nucleic acid-binding domain and plays an important role in RNA metabolism. However, the RNA-binding property of SMN is poorly understood. Here we employ iterative in vitro selection and chemical structure probing to identify sequence and structural motif(s) critical for RNA–SMN interactions. Our results reveal that motifs that drive RNA–SMN interactions are diverse and suggest that tight RNA–SMN interaction requires presence of multiple contact sites on the RNA molecule. We performed UV crosslinking and immunoprecipitation coupled with high-throughput sequencing (HITS-CLIP) to identify cellular RNA targets of SMN in neuronal SH-SY5Y cells. Results of HITS-CLIP identified a wide variety of targets, including mRNAs coding for ribosome biogenesis and cytoskeleton dynamics. We show critical determinants of ANXA2 mRNA for a direct SMN interaction in vitro. Our data confirms the ability of SMN to discriminate among close RNA sequences, and represent the first validation of a direct interaction of SMN with a cellular RNA target. Our findings suggest direct RNA–SMN interaction as a novel mechanism to initiate the cascade of events leading to the execution of SMN-specific functions.
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Affiliation(s)
- Eric W Ottesen
- Iowa State University, Biomedical Sciences, Ames, IA, USA
| | | | - Diou Luo
- Iowa State University, Biomedical Sciences, Ames, IA, USA
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15
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Andrews RJ, Moss WN. Computational approaches for the discovery of splicing regulatory RNA structures. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194380. [PMID: 31048028 DOI: 10.1016/j.bbagrm.2019.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022]
Abstract
Global RNA structure and local functional motifs mediate interactions important in determining the rates and patterns of mRNA splicing. In this review, we overview approaches for the computational prediction of RNA secondary structure with a special emphasis on the discovery of motifs important to RNA splicing. The process of identifying and modeling potential splicing regulatory structures is illustrated using a recently-developed approach for RNA structural motif discovery, the ScanFold pipeline, which is applied to the identification of a known splicing regulatory structure in influenza virus.
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Affiliation(s)
- Ryan J Andrews
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA
| | - Walter N Moss
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA.
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16
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Singh RN, Singh NN. A novel role of U1 snRNP: Splice site selection from a distance. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:634-642. [PMID: 31042550 DOI: 10.1016/j.bbagrm.2019.04.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 04/15/2019] [Accepted: 04/18/2019] [Indexed: 12/23/2022]
Abstract
Removal of introns by pre-mRNA splicing is fundamental to gene function in eukaryotes. However, understanding the mechanism by which exon-intron boundaries are defined remains a challenging endeavor. Published reports support that the recruitment of U1 snRNP at the 5'ss marked by GU dinucleotides defines the 5'ss as well as facilitates 3'ss recognition through cross-exon interactions. However, exceptions to this rule exist as U1 snRNP recruited away from the 5'ss retains the capability to define the splice site, where the cleavage takes place. Independent reports employing exon 7 of Survival Motor Neuron (SMN) genes suggest a long-distance effect of U1 snRNP on splice site selection upon U1 snRNP recruitment at target sequences with or without GU dinucleotides. These findings underscore that sequences distinct from the 5'ss may also impact exon definition if U1 snRNP is recruited to them through partial complementarity with the U1 snRNA. In this review we discuss the expanded role of U1 snRNP in splice-site selection due to U1 ability to be recruited at more sites than predicted solely based on GU dinucleotides.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America.
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States of America
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17
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Singh NN, Luo D, Singh RN. Pre-mRNA Splicing Modulation by Antisense Oligonucleotides. Methods Mol Biol 2019; 1828:415-437. [PMID: 30171557 DOI: 10.1007/978-1-4939-8651-4_26] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Pre-mRNA splicing, a dynamic process of intron removal and exon joining, is governed by a combinatorial control exerted by overlapping cis-elements that are unique to each exon and its flanking intronic sequences. Splicing cis-elements are usually 4-to-8-nucleotide-long linear motifs that provide binding sites for specific proteins. Pre-mRNA splicing is also influenced by secondary and higher order RNA structures that affect accessibility of splicing cis-elements. Antisense oligonucleotides (ASOs) that block splicing cis-elements and/or affect RNA structure have been shown to modulate splicing in vivo. Therefore, ASO-based strategies have emerged as a powerful tool for therapeutic manipulation of splicing in pathological conditions. Here we describe an ASO-based approach to increase the production of the full-length SMN2 mRNA in spinal muscular atrophy patient cells.
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Affiliation(s)
- Natalia N Singh
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
| | - Diou Luo
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
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18
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Wang Y, Xu C, Ma L, Mou Y, Zhang B, Zhou S, Tian Y, Trinh J, Zhang X, Li XJ. Drug screening with human SMN2 reporter identifies SMN protein stabilizers to correct SMA pathology. Life Sci Alliance 2019; 2:2/2/e201800268. [PMID: 30910806 PMCID: PMC6435041 DOI: 10.26508/lsa.201800268] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 01/14/2023] Open
Abstract
Spinal muscular atrophy (SMA), the leading genetic cause of infant mortality, is caused by reduced levels of functional survival motor neuron (SMN) protein. To identify therapeutic agents for SMA, we established a versatile SMN2-GFP reporter line by targeting the human SMN2 gene. We then screened a compound library and identified Z-FA-FMK as a potent candidate. Z-FA-FMK, a cysteine protease inhibitor, increased functional SMN through inhibiting the protease-mediated degradation of both full-length and exon 7-deleted forms of SMN. Further studies reveal that CAPN1, CAPN7, CTSB, and CTSL mediate the degradation of SMN proteins, providing novel targets for SMA. Notably, Z-FA-FMK mitigated mitochondriopathy and neuropathy in SMA patient-derived motor neurons and showed protective effects in SMA animal model after intracerebroventricular injection. E64d, another cysteine protease inhibitor which can pass through the blood-brain barrier, showed even more potent therapeutic effects after subcutaneous delivery to SMA mice. Taken together, we have successfully established a human SMN2 reporter for future drug discovery and identified the potential therapeutic value of cysteine protease inhibitors in treating SMA via stabilizing SMN proteins.
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Affiliation(s)
- Yiran Wang
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Chongchong Xu
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Lin Ma
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Reconstruction and Regeneration of Spine and Spinal Cord Injury, Ministry of Education, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, Tongji University, School of Medicine, Shanghai, China
| | - Yongchao Mou
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Bowen Zhang
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Shanshan Zhou
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yue Tian
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jessica Trinh
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA
| | - Xiaoqing Zhang
- Brain and Spinal Cord Innovative Research Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, China .,Key Laboratory of Reconstruction and Regeneration of Spine and Spinal Cord Injury, Ministry of Education, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, Tongji University, School of Medicine, Shanghai, China.,Tsingtao Advanced Research Institute, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.,Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xue-Jun Li
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, USA .,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
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19
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Abstract
BACKGROUND Spinal muscular atrophy (SMA) is a neuromuscular disorder classified into four types based on the age of onset of the disease. Early onset is correlated with a higher mortality rate, mainly due to respiratory complications. Valproic acid (VPA) is a histone deacetylase (HDAC) inhibitor that has shown positive results on SMA both in experimental and cohort studies. OBJECTIVES This systematic review and meta-analysis aimed to investigate the efficacy and safety of VPA in patients with SMA. METHODS Eleven databases were systematically searched on 30 May 2017 for clinical trials that reported the efficacy and safety of VPA in SMA patients. The primary outcome was the efficacy of VPA in terms of gross motor function and expression of both full-length spinal motor neuron (SMN) gene (FL-SMN) and exon 7-lacking SMN. The secondary outcome was the safety of VPA in terms of reported adverse effects. The protocol was registered at PROSPERO (CRD42017067203). RESULTS Five of the ten included studies were used in the meta-analysis (n = 126). The overall effect estimate, comparing pre- and post-VPA treatment, regardless of carnitine co-administration and design of the studies, showed significant improvement in gross motor function (standard mean difference [SMD] = 0.302, 95% confidence interval [CI] 0.048-0.556, P = 0.02) using the Hammersmith Functional Motor Scale (HFMS), Modified Hammersmith Functional Motor Scale (MHFMS), and MHFMS-Extend, with no significant heterogeneity. Similarly, in non-randomized controlled studies, the results indicated that there was a significant improvement detected (SMD = 0.335, 95% CI 0.041-0.628, P = 0.025), with no significant heterogeneity. Meanwhile, our results suggest that there was no significant improvement in treatment with co-administered carnitine (SMD = 0.28, 95% CI - 0.02 to 0.581, P = 0.067). No significant differences were found between pre- and post-VPA treatment co-administered with carnitine, in terms of the change in FL-SMN and exon 7-lacking SMN. Qualitative synthesis showed that other motor functions were not improved, while respiratory function test results were contradictory. Regarding the safety of the treatment, a double-blind, randomized, placebo-controlled trial reported no statistically significant differences for adverse events (AEs) between groups. Moreover, most of the included studies reported no serious AEs related to VPA use, although weight gain, gastrointestinal symptoms and respiratory symptoms were notable problems. CONCLUSIONS Our study suggests that VPA treatment results in an improvement in gross motor functions for SMA patients, but not in other assessments of motor function or, possibly, in respiratory function. Furthermore, VPA appears to be a relatively safe drug, although treatment may be associated with a wide range of AEs (including body weight increase, fatigue, fever, flu-like symptoms, irritability, and pain). Double-blind, randomized, controlled trials are required to confirm these findings.
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20
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Schellino R, Boido M, Borsello T, Vercelli A. Pharmacological c-Jun NH 2-Terminal Kinase (JNK) Pathway Inhibition Reduces Severity of Spinal Muscular Atrophy Disease in Mice. Front Mol Neurosci 2018; 11:308. [PMID: 30233310 PMCID: PMC6131195 DOI: 10.3389/fnmol.2018.00308] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/14/2018] [Indexed: 12/20/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a severe neurodegenerative disorder that occurs in early childhood. The disease is caused by the deletion/mutation of the survival motor neuron 1 (SMN1) gene resulting in progressive skeletal muscle atrophy and paralysis, due to the degeneration of spinal motor neurons (MNs). Currently, the cellular and molecular mechanisms underlying MN death are only partly known, although recently it has been shown that the c-Jun NH2-terminal kinase (JNK)-signaling pathway might be involved in the SMA pathogenesis. After confirming the activation of JNK in our SMA mouse model (SMN2+/+; SMNΔ7+/+; Smn−/−), we tested a specific JNK-inhibitor peptide (D-JNKI1) on these mice, by chronic administration from postnatal day 1 to 10, and histologically analyzed the spinal cord and quadriceps muscle at age P12. We observed that D-JNKI1 administration delayed MN death and decreased inflammation in spinal cord. Moreover, the inhibition of JNK pathway improved the trophism of SMA muscular fibers and the size of the neuromuscular junctions (NMJs), leading to an ameliorated innervation of the muscles that resulted in improved motor performances and hind-limb muscular tone. Finally, D-JNKI1 treatment slightly, but significantly increased lifespan in SMA mice. Thus, our results identify JNK as a promising target to reduce MN cell death and progressive skeletal muscle atrophy, providing insight into the role of JNK-pathway for developing alternative pharmacological strategies for the treatment of SMA.
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Affiliation(s)
- Roberta Schellino
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi (NICO), University of Turin, Turin, Italy
| | - Marina Boido
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi (NICO), University of Turin, Turin, Italy.,National Institute of Neuroscience (INN), Turin, Italy
| | - Tiziana Borsello
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy.,Department of Neuroscience, IRCCS-Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Alessandro Vercelli
- Department of Neuroscience Rita Levi Montalcini, Neuroscience Institute Cavalieri Ottolenghi (NICO), University of Turin, Turin, Italy.,National Institute of Neuroscience (INN), Turin, Italy
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21
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Ramalho TC, de Castro AA, Tavares TS, Silva MC, Silva DR, Cesar PH, Santos LA, da Cunha EFF, Nepovimova E, Kuca K. Insights into the pharmaceuticals and mechanisms of neurological orphan diseases: Current Status and future expectations. Prog Neurobiol 2018; 169:135-157. [PMID: 29981392 DOI: 10.1016/j.pneurobio.2018.06.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Accepted: 06/30/2018] [Indexed: 12/20/2022]
Abstract
Several rare or orphan diseases have been characterized that singly affect low numbers of people, but cumulatively reach ∼6%-10% of the population in Europe and in the United States. Human genetics has shown to be broadly effective when evaluating subjacent genetic defects such as orphan genetic diseases, but on the other hand, a modest progress has been achieved toward comprehending the molecular pathologies and designing new therapies. Chemical genetics, placed at the interface of chemistry and genetics, could be employed to understand the molecular mechanisms of subjacent illnesses and for the discovery of new remediation processes. This review debates current progress in chemical genetics, and how a variety of compounds and reaction mechanisms can be used to study and ultimately treat rare genetic diseases. We focus here on a study involving Amyotrophic lateral sclerosis (ALS), Duchenne Muscular Dystrophy (DMD), Spinal muscular atrophy (SMA) and Familial Amyloid Polyneuropathy (FAP), approaching different treatment methods and the reaction mechanisms of several compounds, trying to elucidate new routes capable of assisting in the treatment profile.
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Affiliation(s)
- Teodorico C Ramalho
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil; Center for Basic and Applied Research, Faculty of Informatics and Management, University of Hradec Kralove, Hradec Kralove, Czech Republic.
| | | | - Tássia S Tavares
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil
| | - Maria C Silva
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil
| | - Daniela R Silva
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil
| | - Pedro H Cesar
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil
| | - Lucas A Santos
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil
| | - Elaine F F da Cunha
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil
| | - Eugenie Nepovimova
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic
| | - Kamil Kuca
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic.
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22
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Targeting RNA structure in SMN2 reverses spinal muscular atrophy molecular phenotypes. Nat Commun 2018; 9:2032. [PMID: 29795225 PMCID: PMC5966403 DOI: 10.1038/s41467-018-04110-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 04/04/2018] [Indexed: 01/04/2023] Open
Abstract
Modification of SMN2 exon 7 (E7) splicing is a validated therapeutic strategy against spinal muscular atrophy (SMA). However, a target-based approach to identify small-molecule E7 splicing modifiers has not been attempted, which could reveal novel therapies with improved mechanistic insight. Here, we chose as a target the stem-loop RNA structure TSL2, which overlaps with the 5' splicing site of E7. A small-molecule TSL2-binding compound, homocarbonyltopsentin (PK4C9), was identified that increases E7 splicing to therapeutic levels and rescues downstream molecular alterations in SMA cells. High-resolution NMR combined with molecular modelling revealed that PK4C9 binds to pentaloop conformations of TSL2 and promotes a shift to triloop conformations that display enhanced E7 splicing. Collectively, our study validates TSL2 as a target for small-molecule drug discovery in SMA, identifies a novel mechanism of action for an E7 splicing modifier, and sets a precedent for other splicing-mediated diseases where RNA structure could be similarly targeted.
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23
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Singh RN, Singh NN. Mechanism of Splicing Regulation of Spinal Muscular Atrophy Genes. ADVANCES IN NEUROBIOLOGY 2018; 20:31-61. [PMID: 29916015 DOI: 10.1007/978-3-319-89689-2_2] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spinal muscular atrophy (SMA) is one of the major genetic disorders associated with infant mortality. More than 90% cases of SMA result from deletions or mutations of 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. However, correction of SMN2 exon 7 splicing has proven to confer therapeutic benefits in SMA patients. The only approved drug for SMA is an antisense oligonucleotide (Spinraza™/Nusinersen), which corrects SMN2 exon 7 splicing by blocking intronic splicing silencer N1 (ISS-N1) located immediately downstream of exon 7. ISS-N1 is a complex regulatory element encompassing overlapping negative motifs and sequestering a cryptic splice site. More than 40 protein factors have been implicated in the regulation of SMN exon 7 splicing. There is evidence to support that multiple exons of SMN are alternatively spliced during oxidative stress, which is associated with a growing number of pathological conditions. Here, we provide the most up to date account of the mechanism of splicing regulation of the SMN genes.
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Affiliation(s)
- Ravindra N Singh
- 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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24
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Singh NN, Del Rio-Malewski JB, Luo D, Ottesen EW, Howell MD, Singh RN. Activation of a cryptic 5' splice site reverses the impact of pathogenic splice site mutations in the spinal muscular atrophy gene. Nucleic Acids Res 2017; 45:12214-12240. [PMID: 28981879 PMCID: PMC5716214 DOI: 10.1093/nar/gkx824] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/06/2017] [Indexed: 01/08/2023] Open
Abstract
Spinal muscular atrophy (SMA) is caused by deletions or mutations of the Survival Motor Neuron 1 (SMN1) gene coupled with predominant skipping of SMN2 exon 7. The only approved SMA treatment is an antisense oligonucleotide that targets the intronic splicing silencer N1 (ISS-N1), located downstream of the 5' splice site (5'ss) of exon 7. Here, we describe a novel approach to exon 7 splicing modulation through activation of a cryptic 5'ss (Cr1). We discovered the activation of Cr1 in transcripts derived from SMN1 that carries a pathogenic G-to-C mutation at the first position (G1C) of intron 7. We show that Cr1-activating engineered U1 snRNAs (eU1s) have the unique ability to reprogram pre-mRNA splicing and restore exon 7 inclusion in SMN1 carrying a broad spectrum of pathogenic mutations at both the 3'ss and 5'ss of the exon 7. Employing a splicing-coupled translation reporter, we demonstrate that mRNAs generated by an eU1-induced activation of Cr1 produce full-length SMN. Our findings underscore a wider role for U1 snRNP in splicing regulation and reveal a novel approach for the restoration of SMN exon 7 inclusion for a potential therapy of SMA.
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Affiliation(s)
- Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - José Bruno Del Rio-Malewski
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA.,Interdepartmental Genetics and Genomics Program, Iowa State University, Ames, IA 50011, USA
| | - Diou Luo
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Matthew D Howell
- 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.,Interdepartmental Genetics and Genomics Program, Iowa State University, Ames, IA 50011, USA
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25
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Ottesen EW, Seo J, Singh NN, Singh RN. A Multilayered Control of the Human Survival Motor Neuron Gene Expression by Alu Elements. Front Microbiol 2017; 8:2252. [PMID: 29187847 PMCID: PMC5694776 DOI: 10.3389/fmicb.2017.02252] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 10/31/2017] [Indexed: 12/12/2022] Open
Abstract
Humans carry two nearly identical copies of Survival Motor Neuron gene: SMN1 and SMN2. Mutations or deletions of SMN1, which codes for SMN, cause spinal muscular atrophy (SMA), a leading genetic disease associated with infant mortality. Aberrant expression or localization of SMN has been also implicated in other pathological conditions, including male infertility, inclusion body myositis, amyotrophic lateral sclerosis and osteoarthritis. SMN2 fails to compensate for the loss of SMN1 due to skipping of exon 7, leading to the production of SMNΔ7, an unstable protein. In addition, SMNΔ7 is less functional due to the lack of a critical C-terminus of the full-length SMN, a multifunctional protein. Alu elements are specific to primates and are generally found within protein coding genes. About 41% of the human SMN gene including promoter region is occupied by more than 60 Alu-like sequences. Here we discuss how such an abundance of Alu-like sequences may contribute toward SMA pathogenesis. We describe the likely impact of Alu elements on expression of SMN. We have recently identified a novel exon 6B, created by exonization of an Alu-element located within SMN intron 6. Irrespective of the exon 7 inclusion or skipping, transcripts harboring exon 6B code for the same SMN6B protein that has altered C-terminus compared to the full-length SMN. We have demonstrated that SMN6B is more stable than SMNΔ7 and likely functions similarly to the full-length SMN. We discuss the possible mechanism(s) of regulation of SMN exon 6B splicing and potential consequences of the generation of exon 6B-containing transcripts.
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Affiliation(s)
- Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
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26
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Binding to SMN2 pre-mRNA-protein complex elicits specificity for small molecule splicing modifiers. Nat Commun 2017; 8:1476. [PMID: 29133793 PMCID: PMC5684323 DOI: 10.1038/s41467-017-01559-4] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 09/27/2017] [Indexed: 01/28/2023] Open
Abstract
Small molecule splicing modifiers have been previously described that target the general splicing machinery and thus have low specificity for individual genes. Several potent molecules correcting the splicing deficit of the SMN2 (survival of motor neuron 2) gene have been identified and these molecules are moving towards a potential therapy for spinal muscular atrophy (SMA). Here by using a combination of RNA splicing, transcription, and protein chemistry techniques, we show that these molecules directly bind to two distinct sites of the SMN2 pre-mRNA, thereby stabilizing a yet unidentified ribonucleoprotein (RNP) complex that is critical to the specificity of these small molecules for SMN2 over other genes. In addition to the therapeutic potential of these molecules for treatment of SMA, our work has wide-ranging implications in understanding how small molecules can interact with specific quaternary RNA structures. Small molecules correcting the splicing deficit of the survival of motor neuron 2 (SMN2) gene have been identified as having therapeutic potential. Here, the authors provide evidence that SMN2 mRNA forms a ribonucleoprotein complex that can be specifically targeted by these small molecules.
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27
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Rydzik AM, Warminski M, Sikorski PJ, Baranowski MR, Walczak S, Kowalska J, Zuberek J, Lukaszewicz M, Nowak E, W Claridge TD, Darzynkiewicz E, Nowotny M, Jemielity J. mRNA cap analogues substituted in the tetraphosphate chain with CX2: identification of O-to-CCl2 as the first bridging modification that confers resistance to decapping without impairing translation. Nucleic Acids Res 2017; 45:8661-8675. [PMID: 28666355 PMCID: PMC5587727 DOI: 10.1093/nar/gkx569] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/20/2017] [Indexed: 12/20/2022] Open
Abstract
Analogues of the mRNA 5'-cap are useful tools for studying mRNA translation and degradation, with emerging potential applications in novel therapeutic interventions including gene therapy. We report the synthesis of novel mono- and dinucleotide cap analogues containing dihalogenmethylenebisphosphonate moiety (i.e. one of the bridging O atom substituted with CCl2 or CF2) and their properties in the context of cellular translational and decapping machineries, compared to phosphate-unmodified and previously reported CH2-substituted caps. The analogues were bound tightly to eukaryotic translation initiation factor 4E (eIF4E), with CCl2-substituted analogues having the highest affinity. When incorporated into mRNA, the CCl2-substituted dinucleotide most efficiently promoted cap-dependent translation. Moreover, the CCl2-analogues were potent inhibitors of translation in rabbit reticulocyte lysate. The crystal structure of eIF4E in complex with the CCl2-analogue revealed a significantly different ligand conformation compared to that of the unmodified cap analogue, which likely contributes to the improved binding. Both CCl2- and CF2- analogues showed lower susceptibility to hydrolysis by the decapping scavenger enzyme (DcpS) and, when incorporated into RNA, conferred stability against major cellular decapping enzyme (Dcp2) to transcripts. Furthermore, the use of difluoromethylene cap analogues was exemplified by the development of 19F NMR assays for DcpS activity and eIF4E binding.
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Affiliation(s)
- Anna M Rydzik
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland.,Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Marcin Warminski
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Pawel J Sikorski
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Marek R Baranowski
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Sylwia Walczak
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland.,College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Joanna Kowalska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Joanna Zuberek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Maciej Lukaszewicz
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Elzbieta Nowak
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Ksiecia Trojdena Street, 02-109 Warsaw, Poland
| | - Timothy D W Claridge
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Edward Darzynkiewicz
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland.,Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Marcin Nowotny
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Ksiecia Trojdena Street, 02-109 Warsaw, Poland
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
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28
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Howell MD, Ottesen EW, Singh NN, Anderson RL, Seo J, Sivanesan S, Whitley EM, Singh RN. TIA1 is a gender-specific disease modifier of a mild mouse model of spinal muscular atrophy. Sci Rep 2017; 7:7183. [PMID: 28775379 PMCID: PMC5543135 DOI: 10.1038/s41598-017-07468-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/26/2017] [Indexed: 02/08/2023] Open
Abstract
Spinal muscular atrophy (SMA) is caused by deletions or mutations of Survival Motor Neuron 1 (SMN1) gene. The nearly identical SMN2 cannot compensate for SMN1 loss due to exon 7 skipping. The allele C (C +/+) mouse recapitulates a mild SMA-like phenotype and offers an ideal system to monitor the role of disease-modifying factors over a long time. T-cell-restricted intracellular antigen 1 (TIA1) regulates SMN exon 7 splicing. TIA1 is reported to be downregulated in obese patients, although it is not known if the effect is gender-specific. We show that female Tia1-knockout (Tia1 -/-) mice gain significant body weight (BW) during early postnatal development. We next examined the effect of Tia1 deletion in novel C +/+/Tia1 -/- mice. Underscoring the opposing effects of Tia1 deletion and low SMN level on BW gain, both C +/+ and C +/+/Tia1 -/- females showed similar BW gain trajectory at all time points during our study. We observed early tail necrosis in C +/+/Tia1 -/- females but not in males. We show enhanced impairment of male reproductive organ development and exacerbation of the C +/+/Tia1 -/- testis transcriptome. Our findings implicate a protein factor as a gender-specific modifier of a mild mouse model of SMA.
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Affiliation(s)
- Matthew D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Rachel L Anderson
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
| | - Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA
- Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | | | - Elizabeth M Whitley
- Department of Veterinary Pathology, Iowa State University, Ames, IA, 50011-1250, USA
- Pathogenesis, LLC, Gainesville, Florida, 32614, USA
| | - Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, 50011, USA.
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Singh NN, Howell MD, Androphy EJ, Singh RN. How the discovery of ISS-N1 led to the first medical therapy for spinal muscular atrophy. Gene Ther 2017; 24:520-526. [PMID: 28485722 DOI: 10.1038/gt.2017.34] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 04/14/2017] [Accepted: 04/26/2017] [Indexed: 12/14/2022]
Abstract
Spinal muscular atrophy (SMA), a prominent genetic disease of infant mortality, is caused by low levels of survival motor neuron (SMN) protein owing to deletions or mutations of the SMN1 gene. SMN2, a nearly identical copy of SMN1 present in humans, cannot compensate for the loss of SMN1 because of predominant skipping of exon 7 during pre-mRNA splicing. With the recent US Food and Drug Administration approval of nusinersen (Spinraza), the potential for correction of SMN2 exon 7 splicing as an SMA therapy has been affirmed. Nusinersen is an antisense oligonucleotide that targets intronic splicing silencer N1 (ISS-N1) discovered in 2004 at the University of Massachusetts Medical School. ISS-N1 has emerged as the model target for testing the therapeutic efficacy of antisense oligonucleotides using different chemistries as well as different mouse models of SMA. Here, we provide a historical account of events that led to the discovery of ISS-N1 and describe the impact of independent validations that raised the profile of ISS-N1 as one of the most potent antisense targets for the treatment of a genetic disease. Recent approval of nusinersen provides a much-needed boost for antisense technology that is just beginning to realize its potential. Beyond treating SMA, the ISS-N1 target offers myriad potentials for perfecting various aspects of the nucleic-acid-based technology for the amelioration of the countless number of pathological conditions.
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Affiliation(s)
- N N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - M D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - E J Androphy
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - R N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
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Gender-Specific Amelioration of SMA Phenotype upon Disruption of a Deep Intronic Structure by an Oligonucleotide. Mol Ther 2017; 25:1328-1341. [PMID: 28412171 DOI: 10.1016/j.ymthe.2017.03.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/18/2017] [Accepted: 03/28/2017] [Indexed: 01/01/2023] Open
Abstract
Spinal muscular atrophy (SMA), the leading genetic disease of children, is caused by low levels of survival motor neuron (SMN) protein. Here, we employ A15/283, an antisense oligonucleotide targeting a deep intronic sequence/structure, to examine the impact of restoration of SMN in a mild SMA mouse model. We show gender-specific amelioration of tail necrosis upon subcutaneous administrations of A15/283 into SMA mice at postnatal days 1 and 3. We also demonstrate that a modest increase in SMN due to early administrations of A15/283 dramatically improves testicular development and spermatogenesis. Our results reveal near total correction of expression of several genes in adult testis upon temporary increase in SMN during early postnatal development. This is the first demonstration of in vivo efficacy of an antisense oligonucleotide targeting a deep intronic sequence/structure. This is also the first report of gender-specific amelioration of SMA pathology upon a modest peripheral increase of SMN.
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31
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Bonati U, Holiga Š, Hellbach N, Risterucci C, Bergauer T, Tang W, Hafner P, Thoeni A, Bieri O, Gerlach I, Marquet A, Khwaja O, Sambataro F, Bertolino A, Dukart J, Fischmann A, Fischer D, Czech C. Longitudinal characterization of biomarkers for spinal muscular atrophy. Ann Clin Transl Neurol 2017; 4:292-304. [PMID: 28491897 PMCID: PMC5420809 DOI: 10.1002/acn3.406] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/05/2017] [Indexed: 12/27/2022] Open
Abstract
Objective Recent advances in understanding Spinal Muscular Atrophy (SMA) etiopathogenesis prompted development of potent intervention strategies and raised need for sensitive outcome measures capable of assessing disease progression and response to treatment. Several biomarkers have been proposed; nevertheless, no general consensus has been reached on the most feasible ones. We observed a wide range of measures over 1 year to assess their ability to monitor the disease status and progression. Methods 18 SMA patients and 19 healthy volunteers (HV) were followed in this 52‐weeks observational study. Quantitative‐MRI (qMRI) of both thighs and clinical evaluation of motor function was performed at baseline, 6, 9 and 12 months follow‐up. Blood samples were taken in patients for molecular characterization at screening, 9 and 12 month follow‐up. Progression, responsiveness and reliability of collected indices were quantified. Correlation analysis was performed to test for potential associations. Results QMRI indices, clinical scales and molecular measures showed high to excellent reliability. Significant differences were found between qMRI of SMA patients and HV. Significant associations were revealed between multiple qMRI measures and functional clinical scales. None of the qMRI, clinical, or molecular measures was able to detect significant disease progression over 1 year. Interpretation We probed a variety of quantitative measures for SMA in a slowly‐progressing disease population over 1 year. The presented measures demonstrated potential to provide a closer link to underlying disease biology as compared to conventional functional scales. The proposed biomarker framework can guide implementation of more sensitive endpoints in future clinical trials and prove their utility in search for novel disease‐modifying therapies.
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Affiliation(s)
- Ulrike Bonati
- Division of Neuropediatrics University of Basel Children's Hospital Spitalstrasse 334056 Basel Switzerland.,Department of Neurology University of Basel Hospital Petersgraben 44031 Basel Switzerland
| | - Štefan Holiga
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland.,Max Planck Institute for Human Cognitive and Brain Sciences Stephan str. 1A04103 Leipzig Germany
| | - Nicole Hellbach
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Céline Risterucci
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Tobias Bergauer
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Wakana Tang
- Roche Molecular Diagnostics Research Genomics & Oncology Roche Molecular Systems Inc.4300 Hacienda Dr Pleasanton 94588 California USA
| | - Patricia Hafner
- Division of Neuropediatrics University of Basel Children's Hospital Spitalstrasse 334056 Basel Switzerland.,Department of Neurology University of Basel Hospital Petersgraben 44031 Basel Switzerland.,University Clinics of Internal Medicine Kantonsspital Baselland Bruderholz 4101 Switzerland
| | - Alain Thoeni
- MIAC AG c/o University of Basel Hospital Mittlere-Strasse 834031 Basel Switzerland.,Department of Radiology University of Basel Hospital Petersgraben 44031 Basel Switzerland
| | - Oliver Bieri
- Department of Radiology University of Basel Hospital Petersgraben 44031 Basel Switzerland
| | - Irene Gerlach
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Anne Marquet
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Omar Khwaja
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Fabio Sambataro
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Alessandro Bertolino
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Juergen Dukart
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
| | - Arne Fischmann
- Department of Radiology University of Basel Hospital Petersgraben 44031 Basel Switzerland.,Hirslanden Klinik St. Anna St. Anna-Strasse 326006 Luzern Switzerland
| | - Dirk Fischer
- Division of Neuropediatrics University of Basel Children's Hospital Spitalstrasse 334056 Basel Switzerland.,Department of Neurology University of Basel Hospital Petersgraben 44031 Basel Switzerland
| | - Christian Czech
- Roche Pharma and Early Development Neuroscience, Ophthalmology and Rare Diseases Roche Innovation Center Basel F. Hoffmann-La Roche Ltd Grenzacherstrasse 1244070 Basel Switzerland
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Singh RN, Howell MD, Ottesen EW, Singh NN. Diverse role of survival motor neuron protein. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2017; 1860:299-315. [PMID: 28095296 PMCID: PMC5325804 DOI: 10.1016/j.bbagrm.2016.12.008] [Citation(s) in RCA: 189] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 12/23/2016] [Accepted: 12/30/2016] [Indexed: 02/07/2023]
Abstract
The multifunctional Survival Motor Neuron (SMN) protein is required for the survival of all organisms of the animal kingdom. SMN impacts various aspects of RNA metabolism through the formation and/or interaction with ribonucleoprotein (RNP) complexes. SMN regulates biogenesis of small nuclear RNPs, small nucleolar RNPs, small Cajal body-associated RNPs, signal recognition particles and telomerase. SMN also plays an important role in DNA repair, transcription, pre-mRNA splicing, histone mRNA processing, translation, selenoprotein synthesis, macromolecular trafficking, stress granule formation, cell signaling and cytoskeleton maintenance. The tissue-specific requirement of SMN is dictated by the variety and the abundance of its interacting partners. Reduced expression of SMN causes spinal muscular atrophy (SMA), a leading genetic cause of infant mortality. SMA displays a broad spectrum ranging from embryonic lethality to an adult onset. Aberrant expression and/or localization of SMN has also been associated with male infertility, inclusion body myositis, amyotrophic lateral sclerosis and osteoarthritis. This review provides a summary of various SMN functions with implications to a better understanding of SMA and other pathological conditions.
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Affiliation(s)
- Ravindra N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
| | - Matthew D Howell
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Eric W Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
| | - Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States
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33
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Ottesen EW. ISS-N1 makes the First FDA-approved Drug for Spinal Muscular Atrophy. Transl Neurosci 2017; 8:1-6. [PMID: 28400976 PMCID: PMC5382937 DOI: 10.1515/tnsci-2017-0001] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 01/12/2017] [Indexed: 12/20/2022] Open
Abstract
Spinal muscular atrophy (SMA) is one of the leading genetic diseases of children and infants. SMA is caused by deletions or mutations of Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, cannot compensate for the loss of SMN1 due to predominant skipping of exon 7. While various regulatory elements that modulate SMN2 exon 7 splicing have been proposed, intronic splicing silencer N1 (ISS-N1) has emerged as the most promising target thus far for antisense oligonucleotide-mediated splicing correction in SMA. Upon procuring exclusive license from the University of Massachussets Medical School in 2010, Ionis Pharmaceuticals (formerly ISIS Pharamaceuticals) began clinical development of Spinraza™ (synonyms: Nusinersen, IONIS-SMNRX, ISIS-SMNRX), an antisense drug based on ISS-N1 target. Spinraza™ showed very promising results at all steps of the clinical development and was approved by US Food and Drug Administration (FDA) on December 23, 2016. Spinraza™ is the first FDA-approved treatment for SMA and the first antisense drug to restore expression of a fully functional protein via splicing correction. The success of Spinraza™ underscores the potential of intronic sequences as promising therapeutic targets and sets the stage for further improvement of antisense drugs based on advanced oligonucleotide chemistries and delivery protocols.
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Affiliation(s)
- Eric W. Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
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34
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Seo J, Singh NN, Ottesen EW, Lee BM, Singh RN. A novel human-specific splice isoform alters the critical C-terminus of Survival Motor Neuron protein. Sci Rep 2016; 6:30778. [PMID: 27481219 PMCID: PMC4969610 DOI: 10.1038/srep30778] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 06/22/2016] [Indexed: 12/30/2022] Open
Abstract
Spinal muscular atrophy (SMA), a leading genetic disease of children and infants, is caused by mutations or deletions of Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, fails to compensate for the loss of SMN1 due to skipping of exon 7. SMN2 predominantly produces SMNΔ7, an unstable protein. Here we report exon 6B, a novel exon, generated by exonization of an intronic Alu-like sequence of SMN. We validate the expression of exon 6B-containing transcripts SMN6B and SMN6BΔ7 in human tissues and cell lines. We confirm generation of SMN6B transcripts from both SMN1 and SMN2. We detect expression of SMN6B protein using antibodies raised against a unique polypeptide encoded by exon 6B. We analyze RNA-Seq data to show that hnRNP C is a potential regulator of SMN6B expression and demonstrate that SMN6B is a substrate of nonsense-mediated decay. We show interaction of SMN6B with Gemin2, a critical SMN-interacting protein. We demonstrate that SMN6B is more stable than SMNΔ7 and localizes to both the nucleus and the cytoplasm. Our finding expands the diversity of transcripts generated from human SMN genes and reveals a novel protein isoform predicted to be stably expressed during conditions of stress.
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Affiliation(s)
- Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
| | - Natalia N. Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
| | - Eric W. Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
| | - Brian M. Lee
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
- Center for Advanced Host Defenses, Immunobiotics & Translational Comparative Medicine (CAHDIT), Iowa State University, Ames, IA 50011, USA
| | - Ravindra N. Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
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35
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Seo J, Singh NN, Ottesen EW, Sivanesan S, Shishimorova M, Singh RN. Oxidative Stress Triggers Body-Wide Skipping of Multiple Exons of the Spinal Muscular Atrophy Gene. PLoS One 2016; 11:e0154390. [PMID: 27111068 PMCID: PMC4844106 DOI: 10.1371/journal.pone.0154390] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/12/2016] [Indexed: 12/18/2022] Open
Abstract
Humans carry two nearly identical copies of Survival Motor Neuron gene: SMN1 and SMN2. Loss of SMN1 leads to spinal muscular atrophy (SMA), the most frequent genetic cause of infant mortality. While SMN2 cannot compensate for the loss of SMN1 due to predominant skipping of exon 7, correction of SMN2 exon 7 splicing holds the promise of a cure for SMA. Previously, we used cell-based models coupled with a multi-exon-skipping detection assay (MESDA) to demonstrate the vulnerability of SMN2 exons to aberrant splicing under the conditions of oxidative stress (OS). Here we employ a transgenic mouse model and MESDA to examine the OS-induced splicing regulation of SMN2 exons. We induced OS using paraquat that is known to trigger production of reactive oxygen species and cause mitochondrial dysfunction. We show an overwhelming co-skipping of SMN2 exon 5 and exon 7 under OS in all tissues except testis. We also show that OS increases skipping of SMN2 exon 3 in all tissues except testis. We uncover several new SMN2 splice isoforms expressed at elevated levels under the conditions of OS. We analyze cis-elements and transacting factors to demonstrate the diversity of mechanisms for splicing misregulation under OS. Our results of proteome analysis reveal downregulation of hnRNP H as one of the potential consequences of OS in brain. Our findings suggest SMN2 as a sensor of OS with implications to SMA and other diseases impacted by low levels of SMN protein.
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Affiliation(s)
- Joonbae Seo
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
| | - Natalia N. Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
| | - Eric W. Ottesen
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
| | - Senthilkumar Sivanesan
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
| | - Maria Shishimorova
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
| | - Ravindra N. Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America
- * E-mail:
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36
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Ahmad S, Bhatia K, Kannan A, Gangwani L. Molecular Mechanisms of Neurodegeneration in Spinal Muscular Atrophy. J Exp Neurosci 2016; 10:39-49. [PMID: 27042141 PMCID: PMC4807884 DOI: 10.4137/jen.s33122] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 02/22/2016] [Accepted: 02/25/2016] [Indexed: 02/07/2023] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease with a high incidence and is the most common genetic cause of infant mortality. SMA is primarily characterized by degeneration of the spinal motor neurons that leads to skeletal muscle atrophy followed by symmetric limb paralysis, respiratory failure, and death. In humans, mutation of the Survival Motor Neuron 1 (SMN1) gene shifts the load of expression of SMN protein to the SMN2 gene that produces low levels of full-length SMN protein because of alternative splicing, which are sufficient for embryonic development and survival but result in SMA. The molecular mechanisms of the (a) regulation of SMN gene expression and (b) degeneration of motor neurons caused by low levels of SMN are unclear. However, some progress has been made in recent years that have provided new insights into understanding of the cellular and molecular basis of SMA pathogenesis. In this review, we have briefly summarized recent advances toward understanding of the molecular mechanisms of regulation of SMN levels and signaling mechanisms that mediate neurodegeneration in SMA.
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Affiliation(s)
- Saif Ahmad
- Center of Emphasis in Neurosciences, Texas Tech University Health Sciences Center, El Paso, Texas, USA.; Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas, USA
| | - Kanchan Bhatia
- Center of Emphasis in Neurosciences, Texas Tech University Health Sciences Center, El Paso, Texas, USA.; Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas, USA
| | - Annapoorna Kannan
- Center of Emphasis in Neurosciences, Texas Tech University Health Sciences Center, El Paso, Texas, USA.; Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas, USA
| | - Laxman Gangwani
- Center of Emphasis in Neurosciences, Texas Tech University Health Sciences Center, El Paso, Texas, USA.; Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas, USA
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Simone C, Ramirez A, Bucchia M, Rinchetti P, Rideout H, Papadimitriou D, Re DB, Corti S. Is spinal muscular atrophy a disease of the motor neurons only: pathogenesis and therapeutic implications? Cell Mol Life Sci 2016; 73:1003-20. [PMID: 26681261 PMCID: PMC4756905 DOI: 10.1007/s00018-015-2106-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 01/16/2023]
Abstract
Spinal muscular atrophy (SMA) is a genetic neurological disease that causes infant mortality; no effective therapies are currently available. SMA is due to homozygous mutations and/or deletions in the survival motor neuron 1 gene and subsequent reduction of the SMN protein, leading to the death of motor neurons. However, there is increasing evidence that in addition to motor neurons, other cell types are contributing to SMA pathology. In this review, we will discuss the involvement of non-motor neuronal cells, located both inside and outside the central nervous system, in disease onset and progression. Even if SMN restoration in motor neurons is needed, it has been shown that optimal phenotypic amelioration in animal models of SMA requires a more widespread SMN correction. It has been demonstrated that non-motor neuronal cells are also involved in disease pathogenesis and could have important therapeutic implications. For these reasons it will be crucial to take this evidence into account for the clinical translation of the novel therapeutic approaches.
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Affiliation(s)
- Chiara Simone
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Agnese Ramirez
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Monica Bucchia
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Paola Rinchetti
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Hardy Rideout
- Division of Basic Neurosciences, Biomedical Research Foundation of the Academy of Athens (BRFAA), Soranou Efesiou 4, 115 27, Athens, Greece
| | - Dimitra Papadimitriou
- Division of Basic Neurosciences, Biomedical Research Foundation of the Academy of Athens (BRFAA), Soranou Efesiou 4, 115 27, Athens, Greece
| | - Diane B Re
- Department of Environmental Health Sciences, Columbia University, New York, NY, 10032, USA
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY, 10032, USA
| | - Stefania Corti
- Neuroscience Section, Neurology Unit, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, University of Milan, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy.
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38
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Czech C, Tang W, Bugawan T, Mano C, Horn C, Iglesias VA, Fröhner S, Zaworski PG, Paushkin S, Chen K, Kremer T. Biomarker for Spinal Muscular Atrophy: Expression of SMN in Peripheral Blood of SMA Patients and Healthy Controls. PLoS One 2015; 10:e0139950. [PMID: 26468953 PMCID: PMC4607439 DOI: 10.1371/journal.pone.0139950] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 09/17/2015] [Indexed: 11/24/2022] Open
Abstract
Spinal muscular atrophy is caused by a functional deletion of SMN1 on Chromosome 5, which leads to a progressive loss of motor function in affected patients. SMA patients have at least one copy of a similar gene, SMN2, which produces functional SMN protein, although in reduced quantities. The severity of SMA is variable, partially due to differences in SMN2 copy numbers. Here, we report the results of a biomarker study characterizing SMA patients of varying disease severity. SMN copy number, mRNA and Protein levels in whole blood of patients were measured and compared against a cohort of healthy controls. The results show differential regulation of expression of SMN2 in peripheral blood between patients and healthy subjects.
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Affiliation(s)
- Christian Czech
- Roche Pharmaceutical Research & Early Development, Neuroscience, Roche Innovation Center Basel F. Hoffmann –La Roche, Basel
- * E-mail:
| | - Wakana Tang
- Research - Genomics & Oncology, Roche Molecular Systems, Inc., Pleasanton, CA, United States of America
| | - Teodorica Bugawan
- Research - Genomics & Oncology, Roche Molecular Systems, Inc., Pleasanton, CA, United States of America
| | - Calvin Mano
- Research - Genomics & Oncology, Roche Molecular Systems, Inc., Pleasanton, CA, United States of America
| | - Carsten Horn
- Roche Pharmaceutical Research & Early Development, Neuroscience, Roche Innovation Center Basel F. Hoffmann –La Roche, Basel
| | - Victor Alejandro Iglesias
- Roche Pharmaceutical Research & Early Development, Neuroscience, Roche Innovation Center Basel F. Hoffmann –La Roche, Basel
| | | | | | | | - Karen Chen
- SMA Foundation, New York, NY, United States of America
| | - Thomas Kremer
- Roche Pharmaceutical Research & Early Development, Neuroscience, Roche Innovation Center Basel F. Hoffmann –La Roche, Basel
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39
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Genabai NK, Ahmad S, Zhang Z, Jiang X, Gabaldon CA, Gangwani L. Genetic inhibition of JNK3 ameliorates spinal muscular atrophy. Hum Mol Genet 2015; 24:6986-7004. [PMID: 26423457 DOI: 10.1093/hmg/ddv401] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/21/2015] [Indexed: 01/04/2023] Open
Abstract
Mutation of the Survival Motor Neuron 1 (SMN1) gene causes spinal muscular atrophy (SMA), an autosomal recessive neurodegenerative disorder that occurs in early childhood. Degeneration of spinal motor neurons caused by SMN deficiency results in progressive muscle atrophy and death in SMA. The molecular mechanism underlying neurodegeneration in SMA is unknown. No treatment is available to prevent neurodegeneration and reduce the burden of illness in SMA. We report that the c-Jun NH2-terminal kinase (JNK) signaling pathway mediates neurodegeneration in SMA. The neuron-specific isoform JNK3 is required for neuron degeneration caused by SMN deficiency. JNK3 deficiency reduces degeneration of cultured neurons caused by low levels of SMN. Genetic inhibition of JNK pathway in vivo by Jnk3 knockout results in amelioration of SMA phenotype. JNK3 deficiency prevents the loss of spinal cord motor neurons, reduces muscle degeneration, improves muscle fiber thickness and muscle growth, improves motor function and overall growth and increases lifespan of mice with SMA that shows a systemic rescue of phenotype by a SMN-independent mechanism. JNK3 represents a potential (non-SMN) therapeutic target for the treatment of SMA.
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Affiliation(s)
- Naresh K Genabai
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Saif Ahmad
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Zhanying Zhang
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Xiaoting Jiang
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Cynthia A Gabaldon
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Laxman Gangwani
- Center of Emphasis in Neurosciences and Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
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40
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Mechanistic principles of antisense targets for the treatment of spinal muscular atrophy. Future Med Chem 2015; 7:1793-808. [PMID: 26381381 DOI: 10.4155/fmc.15.101] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a major neurodegenerative disorder of children and infants. SMA is primarily caused by low levels of SMN protein owing to deletions or mutations of the SMN1 gene. SMN2, a nearly identical copy of SMN1, fails to compensate for the loss of the production of the functional SMN protein due to predominant skipping of exon 7. Several compounds, including antisense oligonucleotides (ASOs) that elevate SMN protein from SMN2 hold the promise for treatment. An ASO-based drug currently under Phase III clinical trial employs intronic splicing silencer N1 (ISS-N1) as its target. Cumulative studies on ISS-N1 reveal a wealth of information with significance to the overall therapeutic development for SMA. Here, the authors summarize the mechanistic principles behind various antisense targets currently available for SMA therapy.
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Hett EC, Xu H, Geoghegan KF, Gopalsamy A, Kyne RE, Menard CA, Narayanan A, Parikh MD, Liu S, Roberts L, Robinson RP, Tones MA, Jones LH. Rational targeting of active-site tyrosine residues using sulfonyl fluoride probes. ACS Chem Biol 2015; 10:1094-8. [PMID: 25571984 DOI: 10.1021/cb5009475] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This work describes the first rational targeting of tyrosine residues in a protein binding site by small-molecule covalent probes. Specific tyrosine residues in the active site of the mRNA-decapping scavenger enzyme DcpS were modified using reactive sulfonyl fluoride covalent inhibitors. Structure-based molecular design was used to create an alkyne-tagged probe bearing the sulfonyl fluoride warhead, thus enabling the efficient capture of the protein from a complex proteome. Use of the probe in competition experiments with a diaminoquinazoline DcpS inhibitor permitted the quantification of intracellular target occupancy. As a result, diaminoquinazoline upregulators of survival motor neuron protein that are used for the treatment of spinal muscular atrophy were confirmed as inhibitors of DcpS in human primary cells. This work illustrates the utility of sulfonyl fluoride probes designed to react with specific tyrosine residues of a protein and augments the chemical biology toolkit by these probes uses in target validation and molecular pharmacology.
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Affiliation(s)
- Erik C. Hett
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Hua Xu
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kieran F. Geoghegan
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Ariamala Gopalsamy
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Robert E. Kyne
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Carol A. Menard
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Arjun Narayanan
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Mihir D. Parikh
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Shenping Liu
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Lee Roberts
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Ralph P. Robinson
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Michael A. Tones
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Lyn H. Jones
- Worldwide
Medicinal Chemistry and ‡Rare Disease Research Unit, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, United States
- Structural Biology and Biophysics, Worldwide Medicinal Chemistry, ∥Worldwide Medicinal
Chemistry, and ⊥Primary Pharmacology Group, Pfizer, Eastern Point Road, Groton, Connecticut 06340, United States
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42
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Singh NN, Lee BM, Singh RN. Splicing regulation in spinal muscular atrophy by an RNA structure formed by long-distance interactions. Ann N Y Acad Sci 2015; 1341:176-87. [PMID: 25727246 PMCID: PMC4651915 DOI: 10.1111/nyas.12727] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Humans carry two copies of the survival motor neuron gene: SMN1 and SMN2. Loss of SMN1 coupled with skipping of SMN2 exon 7 causes spinal muscular atrophy (SMA), a leading genetic disease associated with infant mortality. Our discovery of intronic splicing silencer N1 (ISS-N1) is a promising target, currently in a phase III clinical trial, for an antisense oligonucleotide-mediated splicing correction in SMA. We have recently shown that the first residue of ISS-N1 is locked in a unique RNA structure that we term ISTL1 (internal stem through long-distance interaction-1). Complementary strands of ISTL1 are separated from each other by 279 nucleotides. Using site-specific mutations and chemical structure probing, we confirmed the formation and functional significance of ISTL1. Located in the middle of intron 7, the 3' strand of ISTL1 falls within an inhibitory region that we term ISS-N2. We demonstrate that an antisense oligonucleotide-mediated sequestration of ISS-N2 fully corrects SMN2 exon 7 splicing and restores high levels of SMN in SMA patient cells. These results underscore the therapeutic potential of the regulatory information present in a secondary and high-order RNA structure of a human intron.
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Affiliation(s)
- Natalia N Singh
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa
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