1
|
Doi A, Delaney C, Tanner D, Burkhart K, Bell RD. RNA exon editing: Splicing the way to treat human diseases. MOLECULAR THERAPY. NUCLEIC ACIDS 2024; 35:102311. [PMID: 39281698 PMCID: PMC11401238 DOI: 10.1016/j.omtn.2024.102311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 09/18/2024]
Abstract
RNA exon editing is a therapeutic strategy for correcting disease-causing mutations by inducing trans-splicing between a synthetic RNA molecule and an endogenous pre-mRNA target, resulting in functionally restored mRNA and protein. This approach enables the replacement of exons at the kilobase scale, addresses multiple mutations with a single therapy, and maintains native gene expression without changes to DNA. For genes larger than 5 kb, RNA exon editors can be delivered in a single vector despite AAV capacity limitations because only mutated exons need to be replaced. While correcting mutations by trans-splicing has been previously demonstrated, prior attempts were hampered by low efficiency or lack of translation in preclinical models. Advances in synthetic biology, next-generation sequencing, and bioinformatics, with a deeper understanding of mechanisms controlling RNA splicing, have triggered a re-emergence of trans-splicing and the development of new RNA exon editing molecules for treating human disease, including the first application in a clinical trial (this study was registered at ClinicalTrials.gov [NCT06467344]). Here, we provide an overview of RNA splicing, the history of trans-splicing, previously reported therapeutic applications, and how modern advances are enabling the discovery of RNA exon editing molecules for genetic targets unable to be addressed by conventional gene therapy and gene editing approaches.
Collapse
Affiliation(s)
- Akiko Doi
- Ascidian Therapeutics, Boston, MA, USA
| | | | | | | | | |
Collapse
|
2
|
Yokomori R, Kusakabe TG, Nakai K. Characterization of trans-spliced chimeric RNAs: insights into the mechanism of trans-splicing. NAR Genom Bioinform 2024; 6:lqae067. [PMID: 38846348 PMCID: PMC11155486 DOI: 10.1093/nargab/lqae067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 05/13/2024] [Accepted: 05/23/2024] [Indexed: 06/09/2024] Open
Abstract
Trans-splicing is a post-transcriptional processing event that joins exons from separate RNAs to produce a chimeric RNA. However, the detailed mechanism of trans-splicing remains poorly understood. Here, we characterize trans-spliced genes and provide insights into the mechanism of trans-splicing in the tunicate Ciona. Tunicates are the closest invertebrates to humans, and their genes frequently undergo trans-splicing. Our analysis revealed that, in genes that give rise to both trans-spliced and non-trans-spliced messenger RNAs, trans-splice acceptor sites were preferentially located at the first functional acceptor site, and their paired donor sites were weak in both Ciona and humans. Additionally, we found that Ciona trans-spliced genes had GU- and AU-rich 5' transcribed regions. Our data and findings not only are useful for Ciona research community, but may also aid in a better understanding of the trans-splicing mechanism, potentially advancing the development of gene therapy based on trans-splicing.
Collapse
Affiliation(s)
- Rui Yokomori
- Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Takehiro G Kusakabe
- Institute for Integrative Neurobiology, Graduate School of Natural Science, Konan University, Kobe 658-8501, Japan
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
| | - Kenta Nakai
- Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| |
Collapse
|
3
|
van der Bent ML, Evers MM, Vallès A. Emerging Therapies for Huntington's Disease - Focus on N-Terminal Huntingtin and Huntingtin Exon 1. Biologics 2022; 16:141-160. [PMID: 36213816 PMCID: PMC9532260 DOI: 10.2147/btt.s270657] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/14/2022] [Indexed: 11/12/2022]
Abstract
Huntington's disease is a devastating heritable neurodegenerative disorder that is caused by the presence of a trinucleotide CAG repeat expansion in the Huntingtin gene, leading to a polyglutamine tract in the protein. Various mechanisms lead to the production of N-terminal Huntingtin protein fragments, which are reportedly more toxic than the full-length protein. In this review, we summarize the current knowledge on the production and toxicity of N-terminal Huntingtin protein fragments. Further, we expand on various therapeutic strategies targeting N-terminal Huntingtin on the protein, RNA and DNA level. Finally, we compare the therapeutic approaches that are clinically most advanced, including those that do not target N-terminal Huntingtin, discussing differences in mode of action and translational applicability.
Collapse
Affiliation(s)
| | - Melvin M Evers
- uniQure biopharma B.V., Department of Research and Development, Amsterdam, the Netherlands
| | - Astrid Vallès
- uniQure biopharma B.V., Department of Research and Development, Amsterdam, the Netherlands
| |
Collapse
|
4
|
Kaye J, Reisine T, Finkbeiner S. Huntington's disease iPSC models-using human patient cells to understand the pathology caused by expanded CAG repeats. Fac Rev 2022; 11:16. [PMID: 35865413 PMCID: PMC9264339 DOI: 10.12703/r/11-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
A major advance in the study of Huntington's disease (HD) has been the development of human disease models employing induced pluripotent stem cells (iPSCs) derived from patients with HD. Because iPSCs provide an unlimited source of cells and can be obtained from large numbers of HD patients, they are a uniquely valuable tool for investigating disease mechanisms and for discovering potential disease-modifying therapeutics. Here, we summarize some of the important findings in HD pathophysiology that have emerged from studies of patient-derived iPSC lines. Because they retain the genome and actual disease mutations of the patient, they provide a cell source to investigate genetic contributions to the disease. iPSCs provide advantages over other disease models. While iPSC-based technology erases some epigenetic marks, newly developed transdifferentiation methods now let us investigate epigenetic factors that control expression of mutant huntingtin (mHTT). Human HD iPSC lines allow us to investigate how endogenous levels of mHTT affect cell health, in contrast to other models that often rely on overexpressing the protein. iPSCs can be differentiated into neurons and other disease-related cells such as astrocytes from different brain regions to study brain regional differences in the disease process, as well as the cell-cell dependencies involved in HD-associated neurodegeneration. They also serve as a tissue source to investigate factors that impact CAG repeat instability, which is involved in regional differences in neurodegeneration in the HD brain. Human iPSC models can serve as a powerful model system to identify genetic modifiers that may impact disease onset, progression, and symptomatology, providing novel molecular targets for drug discovery.
Collapse
Affiliation(s)
- Julia Kaye
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
| | - Terry Reisine
- Independent Scientific Consultant, Santa Cruz, CA, USA
| | - Steven Finkbeiner
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institutes, San Francisco, CA, USA
- Department of Neurology and Physiology, University of California, San Francisco, CA, USA
| |
Collapse
|
5
|
Kocher T, Petkovic I, Bischof J, Koller U. Current developments in gene therapy for epidermolysis bullosa. Expert Opin Biol Ther 2022; 22:1137-1150. [PMID: 35235467 DOI: 10.1080/14712598.2022.2049229] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION The genodermatosis epidermolysis bullosa (EB) is a monogenetic disease, characterized by severe blister formation on the skin and mucous membranes upon minimal mechanical trauma. Causes for the disease are mutations in genes encoding proteins that are essential for skin integrity. In EB, one of these proteins is either functionally impaired or completely absent. Therefore, the development and improvement of DNA and RNA-based therapeutic approaches for this severe blistering skin disease is mandatory to achieve a treatment option for the patients. AREAS COVERED Currently, there are several forms of DNA/RNA therapies potentially feasible for EB. Whereas some of them are still at the preclinical stage, others are clinically advanced and have already been applied to patients. In particular, this is the case for a cDNA replacement approach successfully applied for a small number of patients with junctional EB. EXPERT OPINION The heterogeneity of EB justifies the development of therapeutic options with distinct modes of action at a DNA or RNA level. Besides, splicing-modulating therapies, based on RNA trans-splicing or short antisense oligonucleotides, especially designer nucleases, have steadily improved in efficiency and safety and thus likely represent the most promising gene therapy tool in the near future.
Collapse
Affiliation(s)
- Thomas Kocher
- EB House Austria, Research Program for Molecular Therapy of Genodermatoses, Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| | - Igor Petkovic
- EB House Austria, Research Program for Molecular Therapy of Genodermatoses, Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| | - Johannes Bischof
- EB House Austria, Research Program for Molecular Therapy of Genodermatoses, Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| | - Ulrich Koller
- EB House Austria, Research Program for Molecular Therapy of Genodermatoses, Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| |
Collapse
|
6
|
Evaluating a Targeted Cancer Therapy Approach Mediated by RNA trans-Splicing In Vitro and in a Xenograft Model for Epidermolysis Bullosa-Associated Skin Cancer. Int J Mol Sci 2022; 23:ijms23010575. [PMID: 35008999 PMCID: PMC8745581 DOI: 10.3390/ijms23010575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/20/2021] [Accepted: 12/24/2021] [Indexed: 02/04/2023] Open
Abstract
Conventional anti-cancer therapies based on chemo- and/or radiotherapy represent highly effective means to kill cancer cells but lack tumor specificity and, therefore, result in a wide range of iatrogenic effects. A promising approach to overcome this obstacle is spliceosome-mediated RNA trans-splicing (SMaRT), which can be leveraged to target tumor cells while leaving normal cells unharmed. Notably, a previously established RNA trans-splicing molecule (RTM44) showed efficacy and specificity in exchanging the coding sequence of a cancer target gene (Ct-SLCO1B3) with the suicide gene HSV1-thymidine kinase in a colorectal cancer model, thereby rendering tumor cells sensitive to the prodrug ganciclovir (GCV). In the present work, we expand the application of this approach, using the same RTM44 in aggressive skin cancer arising in the rare genetic skin disease recessive dystrophic epidermolysis bullosa (RDEB). Stable expression of RTM44, but not a splicing-deficient control (NC), in RDEB-SCC cells resulted in expression of the expected fusion product at the mRNA and protein level. Importantly, systemic GCV treatment of mice bearing RTM44-expressing cancer cells resulted in a significant reduction in tumor volume and weight compared with controls. Thus, our results demonstrate the applicability of RTM44-mediated targeting of the cancer gene Ct-SLCO1B3 in a different malignancy.
Collapse
|
7
|
Nisin and non-essential amino acids: new perspective in differentiation of neural progenitors from human-induced pluripotent stem cells in vitro. Hum Cell 2021; 34:1142-1152. [PMID: 33899160 DOI: 10.1007/s13577-021-00537-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 04/16/2021] [Indexed: 12/23/2022]
Abstract
Over the past decades, stem cell therapy has been investigated as a promising approach towards various diseases, including neurodegenerative disorders. Stem cells show the capability to differentiate into neuronal progenitor cells in vitro. In the present study, the differentiation potential of human-induced pluripotent stem cells (hiPSCs) into neural lineages was examined under the efficient induction media containing forskolin and 3-isobutyl-1-methyl-xanthine (IBMX) in the presence of nisin (Ni), non-essential amino acids (NEAA) and combination of those (NEAA-Ni) in vitro. The optimum concentrations of these factors were obtained by MTT assay and acridine orange (AO) staining. The effect of Ni and NEAA on the expression rate of neural-specific markers including NSE, MAP2, and ß-tubulin III was studied via immunocytochemistry (ICC) and real-time RT-PCR analyses. Our results indicated that the induction medium containing Ni or NEAA increased the gene and protein expression of NSE, MAP2, and β-tubulin III on the 14th differentiation day. On the other hand, NEAA-Ni showed a less-differentiated hiPSCs compared to Ni and NEAA alone. In conclusion, the obtained results illustrated that Ni and NEAA could be applied as effective factors for neural differentiation of hiPSCs in the future.
Collapse
|
8
|
Abstract
BACKGROUND RNA trans-splicing joins exons from different pre-mRNA transcripts to generate a chimeric product. Trans-splicing can also occur at the protein level, with split inteins mediating the ligation of separate gene products to generate a mature protein. SOURCES OF DATA Comprehensive literature search of published research papers and reviews using Pubmed. AREAS OF AGREEMENT Trans-splicing techniques have been used to target a wide range of diseases in both in vitro and in vivo models, resulting in RNA, protein and functional correction. AREAS OF CONTROVERSY Off-target effects can lead to therapeutically undesirable consequences. In vivo efficacy is typically low, and delivery issues remain a challenge. GROWING POINTS Trans-splicing provides a promising avenue for developing novel therapeutic approaches. However, much more research needs to be done before developing towards preclinical studies. AREAS TIMELY FOR DEVELOPING RESEARCH Increasing trans-splicing efficacy and specificity by rational design, screening and competitive inhibition of endogenous cis-splicing.
Collapse
Affiliation(s)
- Elizabeth M Hong
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Carin K Ingemarsdotter
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Andrew M L Lever
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
| |
Collapse
|
9
|
Neural In Vitro Models for Studying Substances Acting on the Central Nervous System. Handb Exp Pharmacol 2020; 265:111-141. [PMID: 32594299 DOI: 10.1007/164_2020_367] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Animal models have been greatly contributing to our understanding of physiology, mechanisms of diseases, and toxicity. Yet, their limitations due to, e.g., interspecies variation are reflected in the high number of drug attrition rates, especially in central nervous system (CNS) diseases. Therefore, human-based neural in vitro models for studying safety and efficacy of substances acting on the CNS are needed. Human iPSC-derived cells offer such a platform with the unique advantage of reproducing the "human context" in vitro by preserving the genetic and molecular phenotype of their donors. Guiding the differentiation of hiPSC into cells of the nervous system and combining them in a 2D or 3D format allows to obtain complex models suitable for investigating neurotoxicity or brain-related diseases with patient-derived cells. This chapter will give an overview over stem cell-based human 2D neuronal and mixed neuronal/astrocyte models, in vitro cultures of microglia, as well as CNS disease models and considers new developments in the field, more specifically the use of brain organoids and 3D bioprinted in vitro models for safety and efficacy evaluation.
Collapse
|
10
|
Perrone B, La Cognata V, Sprovieri T, Ungaro C, Conforti FL, Andò S, Cavallaro S. Alternative Splicing of ALS Genes: Misregulation and Potential Therapies. Cell Mol Neurobiol 2020; 40:1-14. [PMID: 31385134 DOI: 10.1007/s10571-019-00717-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/31/2019] [Indexed: 12/12/2022]
Abstract
Neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Parkinson's, Alzheimer's, and Huntington's disease affect a rapidly increasing population worldwide. Although common pathogenic mechanisms have been identified (e.g., protein aggregation or dysfunction, immune response alteration and axonal degeneration), the molecular events underlying timing, dosage, expression, and location of RNA molecules are still not fully elucidated. In particular, the alternative splicing (AS) mechanism is a crucial player in RNA processing and represents a fundamental determinant for brain development, as well as for the physiological functions of neuronal circuits. Although in recent years our knowledge of AS events has increased substantially, deciphering the molecular interconnections between splicing and ALS remains a complex task and still requires considerable efforts. In the present review, we will summarize the current scientific evidence outlining the involvement of AS in the pathogenic processes of ALS. We will also focus on recent insights concerning the tuning of splicing mechanisms by epigenomic and epi-transcriptomic regulation, providing an overview of the available genomic technologies to investigate AS drivers on a genome-wide scale, even at a single-cell level resolution. In the future, gene therapy strategies and RNA-based technologies may be utilized to intercept or modulate the splicing mechanism and produce beneficial effects against ALS.
Collapse
Affiliation(s)
- Benedetta Perrone
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Valentina La Cognata
- Institute for Biomedical Research and Innovation, National Research Council, Catania, Italy
| | - Teresa Sprovieri
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Carmine Ungaro
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Francesca Luisa Conforti
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy
| | - Sebastiano Andò
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy
- Centro Sanitario, University of Calabria, Arcavacata di Rende, Cosenza, Italy
| | - Sebastiano Cavallaro
- Institute for Biomedical Research and Innovation, National Research Council, Catania, Italy.
| |
Collapse
|
11
|
Bordoni M, Rey F, Fantini V, Pansarasa O, Di Giulio AM, Carelli S, Cereda C. From Neuronal Differentiation of iPSCs to 3D Neuro-Organoids: Modelling and Therapy of Neurodegenerative Diseases. Int J Mol Sci 2018; 19:E3972. [PMID: 30544711 PMCID: PMC6321164 DOI: 10.3390/ijms19123972] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/27/2018] [Accepted: 12/07/2018] [Indexed: 12/15/2022] Open
Abstract
In the last decade, the advances made into the reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) led to great improvements towards their use as models of diseases. In particular, in the field of neurodegenerative diseases, iPSCs technology allowed to culture in vitro all types of patient-specific neural cells, facilitating not only the investigation of diseases' etiopathology, but also the testing of new drugs and cell therapies, leading to the innovative concept of personalized medicine. Moreover, iPSCs can be differentiated and organized into 3D organoids, providing a tool which mimics the complexity of the brain's architecture. Furthermore, recent developments in 3D bioprinting allowed the study of physiological cell-to-cell interactions, given by a combination of several biomaterials, scaffolds, and cells. This technology combines bio-plotter and biomaterials in which several types of cells, such as iPSCs or differentiated neurons, can be encapsulated in order to develop an innovative cellular model. IPSCs and 3D cell cultures technologies represent the first step towards the obtainment of a more reliable model, such as organoids, to facilitate neurodegenerative diseases' investigation. The combination of iPSCs, 3D organoids and bioprinting will also allow the development of new therapeutic approaches. Indeed, on the one hand they will lead to the development of safer and patient-specific drugs testing but, also, they could be developed as cell-therapy for curing neurodegenerative diseases with a regenerative medicine approach.
Collapse
Affiliation(s)
- Matteo Bordoni
- Genomic and Post-Genomic Center, IRCCS Mondino Foundation, 27100 Pavia, Italy.
| | - Federica Rey
- Laboratory of Pharmacology, Department of Health Sciences, University of Milan, via A. di Rudinì 8, 20142 Milan, Italy.
| | - Valentina Fantini
- Department of Brain and Behavioural Sciences, University of Pavia, 27100 Pavia, Italy.
- Laboratory of Neurobiology and Neurogenetic, Golgi-Cenci Foundation, 20081 Abbiategrasso, Italy.
| | - Orietta Pansarasa
- Genomic and Post-Genomic Center, IRCCS Mondino Foundation, 27100 Pavia, Italy.
| | - Anna Maria Di Giulio
- Laboratory of Pharmacology, Department of Health Sciences, University of Milan, via A. di Rudinì 8, 20142 Milan, Italy.
- Pediatric Clinical Research Center Fondazione Romeo ed Enrica Invernizzi, University of MilanVia Giovanni Battista Grassi, 74, 20157 Milan, Italy.
| | - Stephana Carelli
- Laboratory of Pharmacology, Department of Health Sciences, University of Milan, via A. di Rudinì 8, 20142 Milan, Italy.
- Pediatric Clinical Research Center Fondazione Romeo ed Enrica Invernizzi, University of MilanVia Giovanni Battista Grassi, 74, 20157 Milan, Italy.
| | - Cristina Cereda
- Genomic and Post-Genomic Center, IRCCS Mondino Foundation, 27100 Pavia, Italy.
- Laboratory of Neurobiology and Neurogenetic, Golgi-Cenci Foundation, 20081 Abbiategrasso, Italy.
| |
Collapse
|