Energetic failure and oxidative stress underlie the Prpf31 splicing factor-related mouse phenotype

Mutations of ubiquitous PRPF splicing factors represent the second cause of retina-specific autosomic dominant retinitis pigmentosa. Prpf31 downregulation decreases phagocytosis of mouse and human retinal pigment epithelial (RPE) cells, thus suggesting similar pathogenesis between species. With time, the mouse RPE ultrastructure shows signs of cellular stress such as cytoplasmic vacuoles. To decipher the primary cellular origin of Prpf31 -related deleterious processes we first confirmed the gradual accumulation of protein and lipid oxidations. We then showed deregulation in the expression levels of oxidative and endoplasmic reticulum stress markers as well as of mitochondrial respiratory chain constituants, first and foremost in the RPE from 3 months onward. For the first time we analyzed the energetic metabolism of freshly dissected RPE/choroid, retina and peritoneal macrophages, and showed that mitochondrial respiration and global energy production were decreased solely in Prpf31 ^+/- RPE cells. Therefore, our results indicate that metabolic impairments and associated stress might contribute to pathogenesis first in Prpf31 ^+/- RPE cells before affecting the retina.