PRPF8-associated retinitis pigmentosa variant induces human neural retina-autonomous photoreceptor defects.

Retinitis pigmentosa (RP) is an inherited retinal disorder characterized by the progressive loss of photoreceptors that currently lacks effective treatment. Here, we investigated the effects of the PRPF8-Y2334N variant on neural retina cells using human induced pluripotent stem cell (hiPSC)-derived retinal organoids. Expression of PRPF8-Y2334N variant resulted in photoreceptor defects, including thinning of the outer segment layer. This indicates that the neural retina is impacted independently of retinal pigment epithelium (RPE). At the molecular level, we observed relatively minor changes in mRNA expression in multiple retinal cells. We also found splicing alterations in genes associated with neural and retinal diseases, including those involved in intraflagellar transport, suggesting that these genes may represent common targets of splicing factor mutations. Finally, we detected the misexpression of several circular RNAs (circRNAs), which could serve as early biomarkers of splicing defects caused by RP mutations. Together, we present a model of RP that recapitulates photoreceptor degeneration and demonstrates that these defects are independent of RPE degeneration.