PUBLICATION

Gene Augmentation of CHM Using Non-Viral Episomal Vectors in Models of Choroideremia

Authors
Toualbi, L., Toms, M., Almeida, P.V., Harbottle, R., Moosajee, M.
ID
ZDB-PUB-231029-65
Date
2023
Source
International Journal of Molecular Sciences   24(20): (Journal)
Registered Authors
Keywords
S/MAR, choroideremia, inherited retinal disease, non-viral gene therapy
MeSH Terms
  • Adult
  • Humans
  • Retinal Dystrophies*/metabolism
  • Animals
  • Retina/metabolism
  • Adaptor Proteins, Signal Transducing/genetics
  • Adaptor Proteins, Signal Transducing/metabolism
  • Plasmids
  • Zebrafish/genetics
  • Zebrafish/metabolism
  • Choroideremia*/genetics
  • Choroideremia*/metabolism
  • Choroideremia*/therapy
  • Mutation
(all 14)
PubMed
37894906 Full text @ Int. J. Mol. Sci.
Abstract
Choroideremia (CHM) is an X-linked chorioretinal dystrophy leading to progressive retinal degeneration that results in blindness by late adulthood. It is caused by mutations in the CHM gene encoding the Rab Escort Protein 1 (REP1), which plays a crucial role in the prenylation of Rab proteins ensuring correct intracellular trafficking. Gene augmentation is a promising therapeutic strategy, and there are several completed and ongoing clinical trials for treating CHM using adeno-associated virus (AAV) vectors. However, late-phase trials have failed to show significant functional improvements and have raised safety concerns about inflammatory events potentially caused by the use of viruses. Therefore, alternative non-viral therapies are desirable. Episomal scaffold/matrix attachment region (S/MAR)-based plasmid vectors were generated containing the human CHM coding sequence, a GFP reporter gene, and ubiquitous promoters (pS/MAR-CHM). The vectors were assessed in two choroideremia disease model systems: (1) CHM patient-derived fibroblasts and (2) chmru848 zebrafish, using Western blotting to detect REP1 protein expression and in vitro prenylation assays to assess the rescue of prenylation function. Retinal immunohistochemistry was used to investigate vector expression and photoreceptor morphology in injected zebrafish retinas. The pS/MAR-CHM vectors generated persistent REP1 expression in CHM patient fibroblasts and showed a significant rescue of prenylation function by 75%, indicating correction of the underlying biochemical defect associated with CHM. In addition, GFP and human REP1 expression were detected in zebrafish microinjected with the pS/MAR-CHM at the one-cell stage. Injected chmru848 zebrafish showed increased survival, prenylation function, and improved retinal photoreceptor morphology. Non-viral S/MAR vectors show promise as a potential gene-augmentation strategy without the use of immunogenic viral components, which could be applicable to many inherited retinal disease genes.
Genes / Markers
Figures
Figure Gallery (4 images)
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Expression
No data available
Phenotype
Mutations / Transgenics
Allele Construct Type Affected Genomic Region
ru848
    Point Mutation
    1 - 1 of 1
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    Human Disease / Model
    Human Disease Fish Conditions Evidence
    choroideremiachmru848/ru848 (AB)standard conditionsTAS
    1 - 1 of 1
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    Sequence Targeting Reagents
    No data available
    Fish
    1 - 2 of 2
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    Antibodies
    Name Type Antigen Genes Isotypes Host Organism
    Ab2-chmmonoclonal
      IgG1Mouse
      Ab4-actbmonoclonal
        IgG2aMouse
        Ab5-rhomonoclonalMouse
        Ab13-vclmonoclonal
          IgG2aMouse
          1 - 4 of 4
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          Orthology
          No data available
          Engineered Foreign Genes
          No data available
          Mapping
          No data available