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Davidsson M, Díaz-Fernández P, Torroba M, Schwich OD, Aldrin-Kirk P, Quintino L, Heuer A, Wang G, Lundberg C, Björklund T. Molecular barcoding of viral vectors enables mapping and optimization of mRNA trans-splicing. RNA 2018; 24:673-687. [PMID: 29386333 PMCID: PMC5900565 DOI: 10.1261/rna.063925.117] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 01/25/2018] [Indexed: 05/04/2023]
Abstract
Genome editing has proven to be highly potent in the generation of functional gene knockouts in dividing cells. In the CNS however, efficient technologies to repair sequences are yet to materialize. Reprogramming on the mRNA level is an attractive alternative as it provides means to perform in situ editing of coding sequences without nuclease dependency. Furthermore, de novo sequences can be inserted without the requirement of homologous recombination. Such reprogramming would enable efficient editing in quiescent cells (e.g., neurons) with an attractive safety profile for translational therapies. In this study, we applied a novel molecular-barcoded screening assay to investigate RNA trans-splicing in mammalian neurons. Through three alternative screening systems in cell culture and in vivo, we demonstrate that factors determining trans-splicing are reproducible regardless of the screening system. With this screening, we have located the most permissive trans-splicing sequences targeting an intron in the Synapsin I gene. Using viral vectors, we were able to splice full-length fluorophores into the mRNA while retaining very low off-target expression. Furthermore, this approach also showed evidence of functionality in the mouse striatum. However, in its current form, the trans-splicing events are stochastic and the overall activity lower than would be required for therapies targeting loss-of-function mutations. Nevertheless, the herein described barcode-based screening assay provides a unique possibility to screen and map large libraries in single animals or cell assays with very high precision.
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Affiliation(s)
- Marcus Davidsson
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Paula Díaz-Fernández
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Marcos Torroba
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Oliver D Schwich
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Patrick Aldrin-Kirk
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Luis Quintino
- CNS Gene Therapy, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Andreas Heuer
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Gang Wang
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Cecilia Lundberg
- CNS Gene Therapy, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Tomas Björklund
- Molecular Neuromodulation, Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
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