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McDowall S, Aung-Htut M, Wilton S, Li D. Antisense oligonucleotides and their applications in rare neurological diseases. Front Neurosci 2024; 18:1414658. [PMID: 39376536 PMCID: PMC11456401 DOI: 10.3389/fnins.2024.1414658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 08/20/2024] [Indexed: 10/09/2024] Open
Abstract
Rare diseases affect almost 500 million people globally, predominantly impacting children and often leading to significantly impaired quality of life and high treatment costs. While significant contributions have been made to develop effective treatments for those with rare diseases, more rapid drug discovery strategies are needed. Therapeutic antisense oligonucleotides can modulate target gene expression with high specificity through various mechanisms determined by base sequences and chemical modifications; and have shown efficacy in clinical trials for a few rare neurological conditions. Therefore, this review will focus on the applications of antisense oligonucleotides, in particular splice-switching antisense oligomers as promising therapeutics for rare neurological diseases, with key examples of Duchenne muscular dystrophy and spinal muscular atrophy. Challenges and future perspectives in developing antisense therapeutics for rare conditions including target discovery, antisense chemical modifications, animal models for therapeutic validations, and clinical trial designs will also be briefly discussed.
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Affiliation(s)
- Simon McDowall
- School of Human Sciences, The University of Western Australia, Crawley, WA, Australia
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Nedlands, WA, Australia
| | - May Aung-Htut
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Nedlands, WA, Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, Australia
| | - Steve Wilton
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Nedlands, WA, Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, Australia
| | - Dunhui Li
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Nedlands, WA, Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, Australia
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2
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Li Y, Chen S, Rahimizadeh K, Zhang Z, Veedu RN. Inhibition of survivin by 2'- O-methyl phosphorothioate-modified steric-blocking antisense oligonucleotides. RSC Adv 2024; 14:13336-13341. [PMID: 38660533 PMCID: PMC11040434 DOI: 10.1039/d4ra01925c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 04/15/2024] [Indexed: 04/26/2024] Open
Abstract
Chemically modified antisense oligonucleotide (ASO) has been established as a successful therapeutic strategy for treating various human diseases. To date, ten ASO drugs, which are capable of either inducing mRNA degradation via RNase H recruitment (fomivirsen, mipomersen, inotersen, volanesorsen and tofersen) or splice modulation (eteplirsen, nusinersen, golodirsen, viltolarsen and casimersen), have been approved by the regulatory agencies for market entry. Nonetheless, none of these approved drugs are prescribed as cancer therapy. Towards this, we have developed steric-blocking ASOs targeting BIRC5 - a well-validated oncogene. Initial screening was performed by transfection of HepG2 cells with seven BIRC5 exon-2 targeting, uniformly 2'-OMe-PS modified ASOs at 400 nM respectively, leading to the identification of two best-performing candidates ASO-2 and ASO-7 in reducing the production of BIRC5 mRNA. Subsequent dose-response assay was conducted via transfection of HepG2 cells by different concentrations (400, 200, 100, 50, 25 nM) of ASO-2 and ASO-7 respectively, showing that both ASOs consistently and efficiently inhibited BIRC5 mRNA expression in a dose-dependent manner. Furthermore, western blot analysis confirmed that ASO-7 could significantly repress survivin production on protein level. Based on our preliminary results, we believe that ASO-7 could be a useful BIRC5 inhibitor for both research purpose and therapeutic development.
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Affiliation(s)
- Yalin Li
- School of Food and Biological Engineering, Henan University of Animal Husbandry and Economy Zhengzhou 450018 China
| | - Suxiang Chen
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University Murdoch 6150 Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science Nedlands WA 6009 Australia
| | - Kamal Rahimizadeh
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University Murdoch 6150 Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science Nedlands WA 6009 Australia
| | - Zhen Zhang
- School of Food and Biological Engineering, Henan University of Animal Husbandry and Economy Zhengzhou 450018 China
| | - Rakesh N Veedu
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University Murdoch 6150 Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science Nedlands WA 6009 Australia
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3
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Le BT, Chen S, Veedu RN. Evaluation of Chemically Modified Nucleic Acid Analogues for Splice Switching Application. ACS OMEGA 2023; 8:48650-48661. [PMID: 38162739 PMCID: PMC10753547 DOI: 10.1021/acsomega.3c07618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/30/2023] [Accepted: 11/21/2023] [Indexed: 01/03/2024]
Abstract
In recent years, several splice switching antisense oligonucleotide (ASO)-based therapeutics have gained significant interest, and several candidates received approval for clinical use for treating rare diseases, in particular, Duchenne muscular dystrophy and spinal muscular atrophy. These ASOs are fully modified; in other words, they are composed of chemically modified nucleic acid analogues instead of natural RNA oligomers. This has significantly improved drug-like properties of these ASOs in terms of efficacy, stability, pharmacokinetics, and safety. Although chemical modifications of oligonucleotides have been discussed previously for numerous applications including nucleic acid aptamers, small interfering RNA, DNAzyme, and ASO, to the best of our knowledge, none of them have solely focused on the analogues that have been utilized for splice switching applications. To this end, we present here a comprehensive review of different modified nucleic acid analogues that have been explored for developing splice switching ASOs. In addition to the antisense chemistry, we also endeavor to provide a brief historical overview of the approved spice switching ASO drugs, including a list of drugs that have entered human clinical trials. We hope this work will inspire further investigations into expanding the potential of novel nucleic acid analogues for constructing splice switching ASOs.
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Affiliation(s)
- Bao T. Le
- Centre
for Molecular Medicine and Innovative Therapeutics, Health Futures
Institute, Murdoch University, Murdoch, Western Australia 6150, Australia
- Precision
Nucleic Acid Therapeutics, Perron Institute
for Neurological and Translational Science, Nedlands, Western Australia 6009, Australia
- ProGenis
Pharmaceuticals Pty Ltd., Bentley, Western Australia 6102, Australia
| | - Suxiang Chen
- Centre
for Molecular Medicine and Innovative Therapeutics, Health Futures
Institute, Murdoch University, Murdoch, Western Australia 6150, Australia
- Precision
Nucleic Acid Therapeutics, Perron Institute
for Neurological and Translational Science, Nedlands, Western Australia 6009, Australia
| | - Rakesh N. Veedu
- Centre
for Molecular Medicine and Innovative Therapeutics, Health Futures
Institute, Murdoch University, Murdoch, Western Australia 6150, Australia
- Precision
Nucleic Acid Therapeutics, Perron Institute
for Neurological and Translational Science, Nedlands, Western Australia 6009, Australia
- ProGenis
Pharmaceuticals Pty Ltd., Bentley, Western Australia 6102, Australia
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4
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Cale JM, Ham KA, Li D, McIntosh CS, Watts GF, Wilton SD, Aung-Htut MT. Induced alternative splicing an opportunity to study PCSK9 protein isoforms at physiologically relevant concentrations. Sci Rep 2023; 13:19725. [PMID: 37957262 PMCID: PMC10643364 DOI: 10.1038/s41598-023-47005-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 11/07/2023] [Indexed: 11/15/2023] Open
Abstract
Splice modulating antisense oligomers (AOs) are increasingly used to modulate RNA processing. While most are investigated for their use as therapeutics, AOs can also be used for basic research. This study examined their use to investigate internally and terminally truncated proprotein convertase subtilisin/kexin type 9 (PCSK9) protein isoforms. Previous studies have used plasmid or viral-vector-mediated protein overexpression to study different PCSK9 protein isoforms, creating an artificial environment within the cell. Here we designed and tested AOs to remove specific exons that encode for PCSK9 protein domains and produced protein isoforms at more physiologically relevant levels. We evaluated the isoforms' expression, secretion, and subsequent impact on the low-density lipoprotein (LDL) receptor and its activity in Huh-7 cells. We found that modifying the Cis-His-rich domain by targeting exons 10 or 11 negatively affected LDL receptor activity and hence did not enhance LDL uptake although the levels of LDL receptor were increased. On the other hand, removing the hinge region encoded by exon 8, or a portion of the prodomain encoded by exon 2, have the potential as therapeutics for hypercholesterolemia. Our findings expand the understanding of PCSK9 isoforms and their impact on the LDL receptor and its activity at physiologically relevant concentrations.
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Affiliation(s)
- Jessica M Cale
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
| | - Kristin A Ham
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
- Perron Institute for Neurological and Translational Science, Perth, WA, 6009, Australia
| | - Dunhui Li
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
- Perron Institute for Neurological and Translational Science, Perth, WA, 6009, Australia
| | - Craig S McIntosh
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
- Perron Institute for Neurological and Translational Science, Perth, WA, 6009, Australia
| | - Gerald F Watts
- School of Medicine, Faculty of Health and Medical Sciences, University of Western Australia, Perth, WA, 6009, Australia
- Cardiometabolic Clinic, Departments of Cardiology and Internal Medicine, Royal Perth Hospital, Perth, WA, 6000, Australia
| | - Steve D Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
- Perron Institute for Neurological and Translational Science, Perth, WA, 6009, Australia
| | - May T Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia.
- Perron Institute for Neurological and Translational Science, Perth, WA, 6009, Australia.
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5
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Ham KA, Johnsen RD, Tchan M, Wilton SD, Aung-Htut MT. Developing Therapeutic Splice-Correcting Antisense Oligomers for Adult-Onset Pompe Disease with c.-32-13T>G Mutation. Methods Mol Biol 2022; 2587:239-251. [PMID: 36401034 DOI: 10.1007/978-1-0716-2772-3_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mutation c.-32-13T>G in the GAA gene impacts normal exon 2 splicing and is found in two-thirds of late-onset Pompe disease cases. We have explored a therapeutic strategy using splice modulating phosphorodiamidate morpholino oligomers to enhance GAA exon 2 inclusion in the mature mRNA of patients carrying this common mutation. We performed in silico analysis of the GAA gene transcript for potential splicing silencers and designed oligomers targeting motifs predicted to enhance exon 2 retention in the mature mRNA. Two patient-derived fibroblasts were obtained from Coriell Institute for Medical Research, and seven fibroblast strains from unrelated patients were supplied by Westmead Hospital in Sydney, Australia. Both fibroblasts and forced-myogenic cells were treated with optimized phosphorodiamidate morpholino oligomers supplied by Sarepta Therapeutics. Total RNA and protein were extracted from the cells after incubation with phosphorodiamidate morpholino oligomers, and RT-PCR and RT-qPCR were performed to confirm exon 2 inclusion is enhanced. Acid α-glucosidase activity and expression levels were also assessed to confirm therapeutic potential.
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Affiliation(s)
- Kristin A Ham
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, Australia.,Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia.,Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Crawley, WA, Australia
| | - Russell D Johnsen
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, Australia.,Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia.,Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Crawley, WA, Australia
| | - Michel Tchan
- Genetic Medicine, Westmead Hospital, Sydney, Australia.,Sydney Medical School, The University of Sydney, Sydney, Australia
| | - Steve D Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, Australia.,Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia.,Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Crawley, WA, Australia
| | - May T Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, Australia. .,Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia. .,Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Crawley, WA, Australia.
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6
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McIntosh CS, Watts GF, Wilton SD, Aung-Htut MT. Splice correction therapies for familial hypercholesterolemic patients with low-density lipoprotein receptor mutations. Curr Opin Lipidol 2021; 32:355-362. [PMID: 34653074 PMCID: PMC8631153 DOI: 10.1097/mol.0000000000000793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Antisense oligomers (ASOs) have been available for decades: however, only recently have these molecules been applied clinically. This review aims to discuss the possible development of antisense-mediated splice correction therapies as precision medicines for familial hypercholesterolemic patients carrying mutations that compromise normal splicing of the low-density lipoprotein receptor (LDLR) gene transcript. RECENT FINDINGS Three antisense drugs are currently being assessed in ongoing clinical trials for dyslipidemias, aiming to lower the plasma concentrations of lipoproteins that lead to end-organ damage, principally coronary artery disease. Although a handful of drugs may be applicable to many patients with familial hypercholesterolemia (FH), mutation-specific personalised antisense drugs may be even more effective in selected patients. Currently, there is no therapy that effectively addresses mutations in the LDLR, the major cause of FH. Many mutations in the LDLR that disrupt normal pre-mRNA processing could be applicable to splice correction therapy to restore receptor activity. SUMMARY Precision medicine could provide long-term economic and social benefits if they can be implemented effectively and sustainably. Many mutations found in the LDLR gene could be amendable to therapeutic splice correction and we should consider developing a therapeutic ASO platform for these mutations.
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Affiliation(s)
- Craig S. McIntosh
- Perron Institute for Neurological and Translational Science, Nedlands, Western Australia, Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, Western Australia, Australia
| | - Gerald F. Watts
- School of Medicine, University of Western Australia
- Lipid Disorders Clinic, Department of Cardiology, Royal Perth Hospital, Perth, Western Australia, Australia
| | - Steve D. Wilton
- Perron Institute for Neurological and Translational Science, Nedlands, Western Australia, Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, Western Australia, Australia
| | - May T. Aung-Htut
- Perron Institute for Neurological and Translational Science, Nedlands, Western Australia, Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, Western Australia, Australia
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7
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McIntosh CS, Li D, Wilton SD, Aung-Htut MT. Polyglutamine Ataxias: Our Current Molecular Understanding and What the Future Holds for Antisense Therapies. Biomedicines 2021; 9:1499. [PMID: 34829728 PMCID: PMC8615177 DOI: 10.3390/biomedicines9111499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 02/07/2023] Open
Abstract
Polyglutamine (polyQ) ataxias are a heterogenous group of neurological disorders all caused by an expanded CAG trinucleotide repeat located in the coding region of each unique causative gene. To date, polyQ ataxias encompass six disorders: spinocerebellar ataxia types 1, 2, 3, 6, 7, and 17 and account for a larger group of disorders simply known as polyglutamine disorders, which also includes Huntington's disease. These diseases are typically characterised by progressive ataxia, speech and swallowing difficulties, lack of coordination and gait, and are unfortunately fatal in nature, with the exception of SCA6. All the polyQ spinocerebellar ataxias have a hallmark feature of neuronal aggregations and share many common pathogenic mechanisms, such as mitochondrial dysfunction, impaired proteasomal function, and autophagy impairment. Currently, therapeutic options are limited, with no available treatments that slow or halt disease progression. Here, we discuss the common molecular and clinical presentations of polyQ spinocerebellar ataxias. We will also discuss the promising antisense oligonucleotide therapeutics being developed as treatments for these devastating diseases. With recent advancements and therapeutic approvals of various antisense therapies, it is envisioned that some of the studies reviewed may progress into clinical trials and beyond.
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Affiliation(s)
- Craig S. McIntosh
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute Murdoch University, Discovery Way, Murdoch, WA 6150, Australia; (C.S.M.); (D.L.); (S.D.W.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Dunhui Li
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute Murdoch University, Discovery Way, Murdoch, WA 6150, Australia; (C.S.M.); (D.L.); (S.D.W.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Steve D. Wilton
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute Murdoch University, Discovery Way, Murdoch, WA 6150, Australia; (C.S.M.); (D.L.); (S.D.W.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA 6009, Australia
| | - May T. Aung-Htut
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute Murdoch University, Discovery Way, Murdoch, WA 6150, Australia; (C.S.M.); (D.L.); (S.D.W.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA 6009, Australia
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8
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Ham KA, Keegan NP, McIntosh CS, Aung-Htut MT, Zaw K, Greer K, Fletcher S, Wilton SD. Induction of cryptic pre-mRNA splice-switching by antisense oligonucleotides. Sci Rep 2021; 11:15137. [PMID: 34302060 PMCID: PMC8302632 DOI: 10.1038/s41598-021-94639-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 07/14/2021] [Indexed: 11/09/2022] Open
Abstract
Antisense oligomers (AOs) are increasingly being used to modulate RNA splicing in live cells, both for research and for the development of therapeutics. While the most common intended effect of these AOs is to induce skipping of whole exons, rare examples are emerging of AOs that induce skipping of only part of an exon, through activation of an internal cryptic splice site. In this report, we examined seven AO-induced cryptic splice sites in six genes. Five of these cryptic splice sites were discovered through our own experiments, and two originated from other published reports. We modelled the predicted effects of AO binding on the secondary structure of each of the RNA targets, and how these alterations would in turn affect the accessibility of the RNA to splice factors. We observed that a common predicted effect of AO binding was disruption of the exon definition signal within the exon's excluded segment.
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Affiliation(s)
- Kristin A Ham
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia
| | - Niall P Keegan
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia
| | - Craig S McIntosh
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia
| | - May T Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia
| | - Khine Zaw
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia.,Department of Biochemistry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Kane Greer
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia
| | - Steve D Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, 6150, Australia. .,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, 6009, Australia.
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9
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Li D, McIntosh CS, Mastaglia FL, Wilton SD, Aung-Htut MT. Neurodegenerative diseases: a hotbed for splicing defects and the potential therapies. Transl Neurodegener 2021; 10:16. [PMID: 34016162 PMCID: PMC8136212 DOI: 10.1186/s40035-021-00240-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/23/2021] [Indexed: 12/14/2022] Open
Abstract
Precursor messenger RNA (pre-mRNA) splicing is a fundamental step in eukaryotic gene expression that systematically removes non-coding regions (introns) and ligates coding regions (exons) into a continuous message (mature mRNA). This process is highly regulated and can be highly flexible through a process known as alternative splicing, which allows for several transcripts to arise from a single gene, thereby greatly increasing genetic plasticity and the diversity of proteome. Alternative splicing is particularly prevalent in neuronal cells, where the splicing patterns are continuously changing to maintain cellular homeostasis and promote neurogenesis, migration and synaptic function. The continuous changes in splicing patterns and a high demand on many cis- and trans-splicing factors contribute to the susceptibility of neuronal tissues to splicing defects. The resultant neurodegenerative diseases are a large group of disorders defined by a gradual loss of neurons and a progressive impairment in neuronal function. Several of the most common neurodegenerative diseases involve some form of splicing defect(s), such as Alzheimer's disease, Parkinson's disease and spinal muscular atrophy. Our growing understanding of RNA splicing has led to the explosion of research in the field of splice-switching antisense oligonucleotide therapeutics. Here we review our current understanding of the effects alternative splicing has on neuronal differentiation, neuronal migration, synaptic maturation and regulation, as well as the impact on neurodegenerative diseases. We will also review the current landscape of splice-switching antisense oligonucleotides as a therapeutic strategy for a number of common neurodegenerative disorders.
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Affiliation(s)
- Dunhui Li
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Craig Stewart McIntosh
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Frank Louis Mastaglia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Steve Donald Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - May Thandar Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia. .,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia.
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10
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Flynn LL, Mitrpant C, Adams A, Pitout IL, Stirnweiss A, Fletcher S, Wilton SD. Targeted SMN Exon Skipping: A Useful Control to Assess In Vitro and In Vivo Splice-Switching Studies. Biomedicines 2021; 9:552. [PMID: 34069072 PMCID: PMC8156830 DOI: 10.3390/biomedicines9050552] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/11/2021] [Accepted: 05/11/2021] [Indexed: 01/23/2023] Open
Abstract
The literature surrounding the use of antisense oligonucleotides continues to grow, with new disease and mechanistic applications constantly evolving. Furthermore, the discovery and advancement of novel chemistries continues to improve antisense delivery, stability and effectiveness. For each new application, a rational sequence design is recommended for each oligomer, as is chemistry and delivery optimization. To confirm oligomer delivery and antisense activity, a positive control AO sequence with well characterized target-specific effects is recommended. Here, we describe splice-switching antisense oligomer sequences targeting the ubiquitously expressed human and mouse SMN and Smn genes for use as control AOs for this purpose. We report two AO sequences that induce targeted skipping of SMN1/SMN2 exon 7 and two sequences targeting the Smn gene, that induce skipping of exon 5 and exon 7. These antisense sequences proved effective in inducing alternative splicing in both in vitro and in vivo models and are therefore broadly applicable as controls. Not surprisingly, we discovered a number of differences in efficiency of exon removal between the two species, further highlighting the differences in splice regulation between species.
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Affiliation(s)
- Loren L. Flynn
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA 6150, Australia; (L.L.F.); (A.A.); (I.L.P.); (S.F.)
- Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia;
- Centre for Neuromuscular & Neurological Disorders, University of Western Australia, Crawley, WA 6009, Australia
- Black Swan Pharmaceuticals, Wake Forest, NC 27587, USA
| | - Chalermchai Mitrpant
- Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia;
- Department of Biochemistry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Abbie Adams
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA 6150, Australia; (L.L.F.); (A.A.); (I.L.P.); (S.F.)
- Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia;
- Centre for Neuromuscular & Neurological Disorders, University of Western Australia, Crawley, WA 6009, Australia
| | - Ianthe L. Pitout
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA 6150, Australia; (L.L.F.); (A.A.); (I.L.P.); (S.F.)
- PYC Therapeutics, Nedlands, WA 6009, Australia;
| | | | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA 6150, Australia; (L.L.F.); (A.A.); (I.L.P.); (S.F.)
- Centre for Neuromuscular & Neurological Disorders, University of Western Australia, Crawley, WA 6009, Australia
- PYC Therapeutics, Nedlands, WA 6009, Australia;
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA 6150, Australia; (L.L.F.); (A.A.); (I.L.P.); (S.F.)
- Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia;
- Centre for Neuromuscular & Neurological Disorders, University of Western Australia, Crawley, WA 6009, Australia
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11
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Abstract
Progress in genomic analytical technologies has improved our possibilities to obtain information regarding DNA, RNA, and their dynamic changes that occur over time or in response to specific challenges. This information describes the blueprint for cells, tissues, and organisms and has fundamental importance for all living organisms. This review focuses on the technological challenges to analyze the transcriptome and what is the impact of transcriptomics on precision medicine. The transcriptome is a term that covers all RNA present in cells and a substantial part of it will never be translated into protein but is nevertheless functional in determining cell phenotype. Recent developments in transcriptomics have challenged the fundamentals of the central dogma of biology by providing evidence of pervasive transcription of the genome. Such massive transcriptional activity is challenging the definition of a gene and especially the term "pseudogene" that has now been demonstrated in many examples to be both transcribed and translated. We also review the common sources of biomaterials for transcriptomics and justify the suitability of whole blood RNA as the current optimal analyte for clinical transcriptomics. At the end of the review, a brief overview of the clinical implications of transcriptomics in clinical trial design and clinical diagnosis is given. Finally, we introduce the transcriptome as a target for modern drug development as a tool for extending our capacity for precision medicine in multiple diseases.
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Affiliation(s)
| | - Abigail L Pfaff
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Murdoch 6150, Australia
- Perron Institute for Neurological and Translational Science, Nedlands 6009, Australia
| | - Vivien J Bubb
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 3BX, UK
| | - John P Quinn
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 3BX, UK
| | - Sulev Koks
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Murdoch 6150, Australia
- Perron Institute for Neurological and Translational Science, Nedlands 6009, Australia
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12
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Novel Lipid-Oligonucleotide Conjugates Containing Long-Chain Sulfonyl Phosphoramidate Groups: Synthesis and Biological Properties. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11031174] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
New lipid conjugates of DNA and RNA incorporating one to four [(4-dodecylphenyl)sulfonyl]phosphoramidate or (hexadecylsulfonyl)phosphoramidate groups at internucleotidic positions near the 3′ or 5′-end were synthesized and characterized. Low cytotoxicity of the conjugates and their ability to be taken up into cells without transfection agents were demonstrated. Lipid-conjugated siRNAs targeting repulsive guidance molecules a (RGMa) have shown a comparable gene silencing activity in PK-59 cells to unmodified control siRNA when delivered into the cells via Lipofectamine mediated transfection.
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13
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Ham KA, Aung-Htut MT, Fletcher S, Wilton SD. Nonsequential Splicing Events Alter Antisense-Mediated Exon Skipping Outcome in COL7A1. Int J Mol Sci 2020; 21:ijms21207705. [PMID: 33081018 PMCID: PMC7590164 DOI: 10.3390/ijms21207705] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/06/2020] [Accepted: 10/14/2020] [Indexed: 11/16/2022] Open
Abstract
The COL7A1 gene encodes homotrimer fibrils essential for anchoring dermal and epidermal layers, and pathogenic mutations in COL7A1 can cause recessive or dominant dystrophic epidermolysis bullosa. As a monogenic disease gene, COL7A1 constitutes a potential target for antisense oligomer-mediated exon skipping, a therapy applicable to a growing number of other genetic disorders. However, certain characteristics of COL7A1: many exons, low average intron size, and repetitive and guanine-cytosine rich coding sequence, present challenges to the design of specific and effective antisense oligomers. While targeting COL7A1 exons 10 and 73 for excision from the mature mRNA, we discovered that antisense oligomers comprised of 2′-O-methyl modified bases on a phosphorothioate backbone and phosphorodiamidate morpholino oligomers produced similar, but distinctive, splicing patterns including excision of adjacent nontargeted exons and/or retention of nearby introns in some transcripts. We found that the nonsequential splicing of certain introns may alter pre-mRNA processing during antisense oligomer-mediated exon skipping and, therefore, additional studies are required to determine if the order of intron removal influences multiexon skipping and/or intron retention in processing of the COL7A1 pre-mRNA.
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Affiliation(s)
- Kristin A. Ham
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch 6150, Australia; (K.A.H.); (M.T.A.-H.); (S.F.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands 6009, Australia
| | - May Thandar Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch 6150, Australia; (K.A.H.); (M.T.A.-H.); (S.F.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands 6009, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch 6150, Australia; (K.A.H.); (M.T.A.-H.); (S.F.)
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch 6150, Australia; (K.A.H.); (M.T.A.-H.); (S.F.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands 6009, Australia
- Correspondence:
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14
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A Splice Intervention Therapy for Autosomal Recessive Juvenile Parkinson's Disease Arising from Parkin Mutations. Int J Mol Sci 2020; 21:ijms21197282. [PMID: 33019779 PMCID: PMC7582384 DOI: 10.3390/ijms21197282] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/16/2020] [Accepted: 09/29/2020] [Indexed: 11/17/2022] Open
Abstract
Parkin-type autosomal recessive juvenile-onset Parkinson’s disease is caused by mutations in the PRKN gene and accounts for 50% of all autosomal recessive Parkinsonism cases. Parkin is a neuroprotective protein that has dual functions as an E3 ligase in the ubiquitin–proteasome system and as a transcriptional repressor of p53. While genomic deletions of PRKN exon 3 disrupt the mRNA reading frame and result in the loss of functional parkin protein, deletions of both exon 3 and 4 maintain the reading frame and are associated with a later onset, milder disease progression, indicating this particular isoform retains some function. Here, we describe in vitro evaluation of antisense oligomers that restore functional parkin expression in cells derived from a Parkinson’s patient carrying a heterozygous PRKN exon 3 deletion, by inducing exon 4 skipping to correct the reading frame. We show that the induced PRKN transcript is translated into a shorter but semi-functional parkin isoform able to be recruited to depolarised mitochondria, and also transcriptionally represses p53 expression. These results support the potential use of antisense oligomers as a disease-modifying treatment for selected pathogenic PRKN mutations.
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15
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McIntosh CS, Aung-Htut MT, Fletcher S, Wilton SD. Removal of the Polyglutamine Repeat of Ataxin-3 by Redirecting pre-mRNA Processing. Int J Mol Sci 2019; 20:ijms20215434. [PMID: 31683630 PMCID: PMC6862616 DOI: 10.3390/ijms20215434] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 02/06/2023] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) is a devastating neurodegenerative disease for which there is currently no cure, nor effective treatment strategy. One of nine polyglutamine disorders known to date, SCA3 is clinically heterogeneous and the main feature is progressive ataxia, which in turn affects speech, balance and gait of the affected individual. SCA3 is caused by an expanded polyglutamine tract in the ataxin-3 protein, resulting in conformational changes that lead to toxic gain of function. The expanded glutamine tract is located at the 5′ end of the penultimate exon (exon 10) of ATXN3 gene transcript. Other studies reported removal of the expanded glutamine tract using splice switching antisense oligonucleotides. Here, we describe improved efficiency in the removal of the toxic polyglutamine tract of ataxin-3 in vitro using phosphorodiamidate morpholino oligomers, when compared to antisense oligonucleotides composed of 2′-O-methyl modified bases on a phosphorothioate backbone. Significant downregulation of both the expanded and non-expanded protein was induced by the morpholino antisense oligomer, with a greater proportion of ataxin-3 protein missing the polyglutamine tract. With growing concerns over toxicity associated with long-term administration of phosphorothioate oligonucleotides, the use of a phosphorodiamidate morpholino oligomer may be preferable for clinical application. These results suggest that morpholino oligomers may provide greater therapeutic benefit for the treatment of spinocerebellar ataxia type 3, without toxic effects.
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Affiliation(s)
- Craig S McIntosh
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch WA 6150, Australia.
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands WA 6009, Australia.
| | - May Thandar Aung-Htut
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch WA 6150, Australia.
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands WA 6009, Australia.
| | - Sue Fletcher
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch WA 6150, Australia.
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands WA 6009, Australia.
| | - Steve D Wilton
- Molecular Therapy Laboratory, Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch WA 6150, Australia.
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands WA 6009, Australia.
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