Single-cell spatial transcriptomics reveals rewiring of RPE and Müller glia signaling toward photoreceptors following outer segment disruption in Prph2C213Y mice.

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 Müller 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 Müller gliosis. Single-cell spatial transcriptomics of wild-type and mutant retinas at 6 months resolved nine cell populations and identified RPE cells and Müller 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 Müller 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 Müller glia toward photoreceptors. These findings indicate that PRPH2-associated retinal dystrophy is a multicellular process in which OS disruption drives coordinated RPE and Müller glial remodeling with potentially protective or pro-degenerative effects, and nominate the RPE Nfib-Fstl1 program, Müller glial AP-1 responses with predicted STAT3 involvement, and support-cell-derived growth factor signaling as candidate mutation-independent therapeutic targets.