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RNAi-based suppression and replacement of rds-peripherin in retinal organotypic culture
Arpad Palfi1, Marius Ader, Anna-Sophia Kiang
1Department of Genetics, Trinity College Dublin, Dublin, Ireland. palfia@tcd.ie
Abstract:
Extensive mutational heterogeneity presents a significant barrier to the development of therapeutics for RDS-peripherin-linked autosomal-dominant retinitis pigmentosa (RP), for which more than 50 disease-related mutations have been identified to date. Mutation-independent suppression, using RNA interference (RNAi), together with simultaneous expression of a replacement rds gene (r-rds, which has been altered to escape suppression but nevertheless encodes wild-type protein) has been explored in COS-7 cells and mouse retinal explants. The efficacy of small interfering and short hairpin RNAs (si/shRNAs) silencing mouse rds, and the function of r-rds (containing degenerate substitutions in the RNAi target sequence) were analyzed at transcript (RT-PCR) and protein (ELISA) levels in COS-7 cells. "Dual-" and "triple-expression" constructs carrying the shRNA suppressor and the marker EGFP with or without the r-rds cassette were electroporated in vitro into retinal explants from 1-day-old pups. The retinae were dissociated at day 14, and transduced cells were FACS-sorted using the coexpressed EGFP marker and analyzed by RT-PCR. si/shRNAs decreased rds mRNA and protein expression by up to 82%, while r-rds was protected from suppression in COS-7 cells. Similarly, efficient RNAi-mediated suppression of endogenous rds was detected in retinal explants, while concomitant rescue of r-rds was also achieved. These data validate the concept of RNAi-based suppression coupled with replacement technology for the development of therapies targeting RDS-linked autosomal-dominant RP, and suggest that such approaches could potentially be used for other autosomal-dominant diseases with similarly extensive intragenic heterogeneity.
Insights
This study demonstrates a novel RNA interference (RNAi) therapy for RDS-peripherin-linked retinitis pigmentosa (RP). The approach silences disease-causing RDS genes while reintroducing a functional replacement, offering hope for genetic eye diseases.
Area of Science:
- Genetics
- Molecular Biology
- Ophthalmology
Background:
- Autosomal-dominant retinitis pigmentosa (RP) linked to RDS-peripherin mutations is challenging to treat due to extensive genetic variations.
- Current therapeutic strategies face limitations in addressing the diverse mutational landscape of this inherited retinal disease.
Purpose of the Study:
- To investigate the efficacy of a combined RNA interference (RNAi) and gene replacement strategy for RDS-peripherin-linked autosomal-dominant RP.
- To develop a mutation-independent therapeutic approach for a heterogeneous genetic disorder.
Main Methods:
- Utilized small interfering RNAs (siRNAs) and short hairpin RNAs (shRNAs) to silence endogenous mouse RDS gene expression in COS-7 cells and retinal explants.
- Constructed a modified replacement RDS gene (r-RDS) with degenerate target sequences to resist RNAi-mediated suppression.
- Analyzed gene and protein expression levels using RT-PCR and ELISA, and assessed therapeutic efficacy in vitro and in mouse retinal explants.
Main Results:
- RNAi-based si/shRNAs effectively reduced RDS mRNA and protein levels by up to 82% in COS-7 cells.
- The modified r-RDS gene was successfully protected from RNAi-mediated suppression, demonstrating its functional expression.
- In mouse retinal explants, efficient suppression of endogenous RDS was observed alongside successful rescue by the r-RDS construct.
Conclusions:
- The combined RNAi-based gene silencing and replacement technology is a validated therapeutic concept for RDS-linked autosomal-dominant RP.
- This approach holds potential for treating other autosomal-dominant diseases characterized by significant intragenic heterogeneity.
- This strategy offers a promising avenue for developing effective treatments for complex genetic retinal disorders.
