Photoreceptor survival in CEP290-retinopathy by Reserpine involves modulation of proteostasis

Photoreceptor cell death is a major cause of incurable vision loss in retinal degeneration, with little to no treatment options available. To identify drug candidates to maintain photoreceptor survival, we performed an unbiased high-throughput screening of over 6,000 bioactive small molecules using retinal organoids differentiated from induced pluripotent stem cells of rd16 mice, which phenocopy Leber congenital amaurosis (LCA) 10 caused by CEP290 mutations. Five positive hits including the lead compound Reserpine were further validated by the improvement of photoreceptor maintenance and survival in organoid cultures and in vivo retina. Subsequent investigation revealed misregulation of autophagy in degenerative retina, which is associated with compromised primary cilium biogenesis. Reserpine largely restored the balance between autophagy and the ubiquitin-proteasome system, and improved primary cilium assembly in vitro and in vivo. This study identified effective drug candidates for treatment of retinal degeneration and highlights the impact of proteostasis in photoreceptor cell death. The generation and characterization of the familial control, LCA-1 and LCA-2 iPSC lines have been previously reported (Shimada et al., 2017). Human retinal organoid differentiation was performed as previously described (Regent et al., 2020). Total RNA was purified from homogenized retinal organoids using TriPure isolation reagent (Roche). Quality of isolated RNAs was assessed using Bioanalyzer RNA 6000 nano assays (Agilent) and high-quality total RNA (RNA integrity number ≥7.5) were used for construction of mRNA sequencing library. 100ng total RNA were used to construct the strand-specific libraries using TruSeq RNA Sample Prep Kit-v2 (Illumina).