RNAseq analysis of fibroblasts, iPSC, iPSC derived RPE and retinal cells from retinitis pigmentosa type 11 patients.

Mutations in pre-mRNA processing factors (PRPFs) account for 40% of autosomal dominant retinitis pigmentosa (RP). It is unclear why mutations in ubiquitously expressed PRPFs cause retinal disease. To understand the molecular basis of this phenotype, we have generated PRPF31 patient-specific optic cups and retinal pigmented epithelium (RPE) from induced pluripotent stem cells (iPSC). Impaired alternative splicing of pre-mRNA splicing, ciliogenesis and cell-to-substrate adherens junction genes was observed in patient-specific retinal cells, but not fibroblasts and iPSCs, providing mechanistic insights into retinal-specific phenotypes of PRPF31-related RP type 11. RPE was the most affected, characterised by loss of apical-basal polarity, reduced trans-epithelial resistance, phagocytic capacity, microvilli, and cilia length and incidence. Disrupted cilia morphology was observed in patient-specific- photoreceptors that progressively displayed features associated with degeneration and cell stress. In situ gene-editing of the patient mutation rescued key structural and functional phenotypes in RPE and photoreceptors, providing conceptual proof for future therapeutic strategies.