ABSTRACT: PRPH2 mutations cause inherited retinal dystrophies (IRDs), but how photoreceptor outer segment (OS) disruption reshapes the surrounding retina remains unclear. Using a heterozygous Prph2C213Y/+ mouse model generated by CRISPR/Cas9, we characterized age-related retinal pathology and responses of retinal pigment epithelium (RPE) and Muller glia. Independent age- and sex-matched cohorts were examined at 1, 3, and 6 months by electroretinography, optical coherence tomography, and fundus autofluorescence. Mutant mice showed rod dysfunction from 1 month, RPE dysfunction from 3 months, and cone dysfunction by 6 months, accompanied by progressive outer retinal thinning and hyperautofluorescent deposits. Histological and ultrastructural analyses revealed OS disorganization, shortened RPE microvilli, RPE monolayer remodeling, increased RPE autofluorescence, and reactive Muller gliosis. Single-cell spatial transcriptomics of wild-type and mutant retinas at 6 months resolved nine cell populations and identified RPE cells and Muller glia as prominently perturbed non-photoreceptor populations. RPE cells showed an epithelial-mesenchymal transition-related remodeling state linked to a candidate Nfib-Fstl1 module, whereas Muller glia showed activation of activator protein 1 (AP-1) regulons, including Fos, Fosl2, and Junb, with predicted targets Osmr, A2m, and Stat3. Cell-cell communication analyses indicated coordinated changes in neuroprotective, inflammatory, and matrix-related signaling from RPE cells and Muller glia toward photoreceptors. These findings indicate that PRPH2-associated retinal dystrophy is a multicellular process in which OS disruption drives coordinated RPE and Muller glial remodeling with potentially protective or pro-degenerative effects, and nominate the RPE Nfib-Fstl1 program, Muller glial AP-1 responses with predicted STAT3 involvement, and support-cell-derived growth factor signaling as candidate mutation-independent therapeutic targets.
