All-in-one AAV-mediated Nrl Gene Inactivation Rescues Retinal Degeneration in Pde6a Mice

Retinitis pigmentosa (RP) is a complex group of inherited retinal diseases characterized by progressive death of photoreceptor cells and eventual blindness. Pde6a, which encodes a cGMP-specific phosphodiesterase, is a crucial pathogenic gene for autosomal recessive RP (RP43); there is no effective therapy for this form of RP. The compact CRISPR/Staphylococcus aureus Cas9 (CRISPR/SaCas9) system, which can be packaged into a single adeno-associated virus (AAV), holds promise for simplifying effective gene therapy. Here, we demonstrated that all-in-one AAV-SaCas9-mediated Nrl gene inactivation can efficiently prevent retinal degeneration in a RP mouse model with Pde6anmf363/nmf363 mutation. We screened single-guide RNAs capable of efficiently editing the mouse Nrl gene in N2a cells and then achieved effective gene editing by using a single AAV to codeliver SaCas9 and an optimal Nrl-sg2 into the mouse retina. Excitingly, in vivo inactivation of Nrl improved photoreceptor cell survival and rescued retinal function in treated Pde6a-deficient mice. Thus, we showed that a practical, gene-independent method, AAV-SaCas9-mediated Nrl inactivation, holds promise for future therapeutic applications in patients with RP.