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Published on: August 14, 2013
Engineered tRNA reduces vision loss in a mouse model of Leber congenital amaurosis
Pawan K Shahi1,2, Enes Akyuz1,2, Lionel Gissot3
1University of Wisconsin-Madison, Department of Pediatrics, Madison, WI, USA.
Abstract:
Premature termination codons (PTCs) are a major class of pathogenic variants that underlie rare inherited disorders, including forms of childhood blindness. Therapeutic suppression of these "nonsense mutations" offers a gene- and position-agnostic strategy to restore protein function. Our previous work established that the W53X PTC in the KCNJ13 gene causes Leber congenital amaurosis type 16 (LCA16) by disrupting the inwardly rectifying potassium channel Kir7.1, leading to retinal pigment epithelium (RPE) dysfunction. Here, we present a proof-of-concept approach using anticodon-engineered transfer RNA (ACE-tRNA) to promote targeted translational readthrough. We engineered a suppressor tRNA encoding tryptophan (ACE-tRNATrp.UAG) to selectively recognize the UAG stop codon at the W53X site, enabling incorporation of the correct amino acid and restoration of full-length Kir7.1 protein. Delivery of ACE-tRNA via helper-dependent adenovirus (HDAd) resulted in robust rescue of channel function in heterologous systems expressing mutant KCNJ13 and in patient-derived human induced pluripotent stem cell (hiPSC)-RPE cells. Functional recovery was confirmed by electrophysiological assays demonstrating restored inwardly rectifying currents and membrane potential. Importantly, subretinal delivery of HDAd-ACE-tRNATrp.UAG in a W53X mouse model led to partial restoration of RPE physiology, as measured by electroretinography, without evidence of retinal toxicity. Together, these findings establish ACE-tRNA-mediated suppression as a viable therapeutic strategy for nonsense mutations in multimeric ion channels and provide a translational framework for precision treatment of inherited retinal diseases.
Insights
Anticodon-engineered transfer RNA (ACE-tRNA) therapy successfully restored Kir7.1 protein function in models of Leber congenital amaurosis type 16. This approach offers a promising strategy for treating inherited retinal diseases caused by nonsense mutations.
Area of Science:
- Genetics
- Molecular Biology
- Ophthalmology
Background:
- Premature termination codons (PTCs) cause rare genetic disorders, including Leber congenital amaurosis type 16 (LCA16), by creating non-functional proteins.
- The W53X PTC in the KCNJ13 gene disrupts the Kir7.1 potassium channel, leading to retinal pigment epithelium (RPE) dysfunction and LCA16.
Purpose of the Study:
- To develop and validate a therapeutic strategy using anticodon-engineered transfer RNA (ACE-tRNA) to suppress the W53X PTC.
- To restore the function of the Kir7.1 potassium channel and RPE cells for potential LCA16 treatment.
Main Methods:
- Engineered a specific suppressor tRNA (ACE-tRNATrp.UAG) to recognize and read through the UAG stop codon at the W53X mutation site.
- Delivered ACE-tRNA using helper-dependent adenovirus (HDAd) vectors in cell culture (heterologous systems, patient-derived hiPSC-RPE) and a W53X mouse model.
- Assessed channel function using electrophysiology and RPE physiology using electroretinography.
Main Results:
- ACE-tRNATrp.UAG successfully promoted translational readthrough, restoring full-length Kir7.1 protein in vitro.
- HDAd-mediated delivery rescued Kir7.1 channel function in mutant KCNJ13-expressing cells and patient-derived hiPSC-RPE cells.
- Subretinal delivery in W53X mice partially restored RPE physiology (electroretinography) without observed retinal toxicity.
Conclusions:
- ACE-tRNA-mediated nonsense suppression is a viable therapeutic approach for KCNJ13 nonsense mutations causing LCA16.
- This strategy shows potential for treating inherited retinal diseases and other disorders caused by nonsense mutations in multimeric ion channels.
- The study provides a translational framework for precision medicine targeting specific genetic defects.
