Abstract
Purpose :
The RHO gene encoding the protein component of rhodopsin is the most frequent causal gene associated with autosomal dominant retinitis pigmentosa, an inherited retinal degeneration that lacks an effective treatment. Among the more than150 mutations reported so far, more than 50 RHO mutations are classified into the misfolding category when the unstable folding of the mutant rod opsin protein eventually leads to photoreceptor death and blindness. We recently identified a novel non-retinoid pharmacological chaperone of rod opsin (YC-001) through a high-throughput screening assay targeting the P23H rod opsin mutant. We hypothesize YC-001 has a universal activity rescuing misfolding rod opsin mutants that cause retinitis pigmentosa.
Methods :
We constructed a small library of plasmids encoding a total of 28 human rhodopsin mutants that were found in human autosomal dominant retinitis pigmentosa cases. These DNA constructs were transfected in high-throughput format and treated with the 9-cis-retinal as the retinoid chaperone, or YC-001, the non-retinoid chaperone. Immunostaining of transfected cells was undertaken without membrane permeabilization, using the anti-rhodopsin B6-30 antibody specific to the N-terminal extracellular/intradiscal epitope. The immunostained rhodopsin mutants that were transported to the cell membrane were imaged and quantified by the high-content imaging technique.
Results :
In agreement with studies by others, most misfolding rhodopsin mutants were localized around the perinuclear region in the transfected cells, due to their defects in folding.
Upon treatment with YC-001, multiple rhodopsin mutants were observed with different degrees of rescued transport on the cell membrane, suggesting a universal pharmacological chaperone activity of YC-001 to stabilize rhodopsin folding.
The activity profile of 9-cis-retinal among the rhodopsin mutants is similar compared to that of YC-001, suggesting a shared binding pocket of the two compounds.
Conclusions :
We identified a novel non-retinoid pharmacological chaperone of rod opsin that stabilizes the folding and rescues the biosynthesis of multiple rhodopsin mutants associated with autosomal dominant retinitis pigmentosa. The universal activity of YC-001 towards multiple rhodopsin mutants implies a broader therapeutic application range for autosomal dominant retinitis pigmentosa.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.