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Yuanyuan Chen, Bing Feng, Owen Clinger, Mark Schurdak, Yibo Xi; Pharmacological chaperones for RHO-associated retinitis pigmentosa. Invest. Ophthalmol. Vis. Sci. 2021;62(8):230.
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© ARVO (1962-2015); The Authors (2016-present)
Genetic mutations in the RHO gene lead to structural disability of the photopigment rhodopsin, resulting in rod cell death and vision loss accounting for 25-30% of autosomal dominant retinitis pigmentosa cases. The goal of this study is to seek pharmacological strategies for preventing rod cell death by restoring rhodopsin homeostasis.
A total of 23 single mutations have been generated on the extracellular side of human rhodopsin, and these cDNA constructs were transfected to NIH3T3 cells in 384 wells. Cells were treated with compounds at 24 h after transfection and DMSO was used as vehicle control. Cell-surface immunostaining of rhodopsin was performed after 24 h of treatment, and immunofluorescence images were taken by a high-content imaging system. Immunofluorescence of rhodopsin per cell was quantified based on the analyses of 400-600 cells per well, averaged by three replicates. Cell viability was quantified by the number of cells per well. A docking calculation was performed by the AutodockVina software using the bovine rhodopsin structure (PDB ID: 1f88) as the structure template. 11-cis-retinal was deleted from the density to leave the chromophore pocked for the docking of small molecules. ΔGs were obtained indicating the stability of the complex of rod opsin with each compound. To test the effect of small molecule chaperone on retinal morphology and function in vivo, we injected YC-001 suspension in PBS intravitreally to the eyes of RhoP23H/+ mice at PND15, OCT and ERGs were taken at PND28.
We showed that three rhodopsin chaperones we identified previously improved the transport of multiple, but not all mutants of rhodopsin to the plasma membrane. Scriptaid showed non-selective rescue to all the mutants of rhodopsin, with high cytotoxicity. YC-001 was docked within the chromophore pocket at the ionone side. One intravitreal injection of YC-001 showed improved scotopic ERG responses in the RhoP23H/+ mice at PND28.
Our results provide a pharmacological profile of two small molecule chaperones towards misfolding rhodopsin mutants, suggesting the efficacy of pharmacological chaperones are highly dependent on the mutation site and residue of rhodopsin. The short-term efficacy of YC-001 in RhoP23H/+ knock-in mice strongly supports that restoring rhodopsin folding can prevent rod cell death caused by RHO mutants that carry mild folding defects.
This is a 2021 ARVO Annual Meeting abstract.
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