Metabolic and Redox Signaling of the Nucleoredoxin-Like-1 Gene for the Treatment of Genetic Retinal Diseases

Abstract

The loss of cone photoreceptor function in retinitis pigmentosa (RP) severely impacts the central and daily vision and quality of life of patients affected by this disease. The loss of cones follows the degeneration of rods, in a manner independent of the causing mutations in numerous genes associated with RP. We have explored this phenomenon and proposed that the loss of rods triggers a reduction in the expression of rod-derived cone viability factor (RdCVF) encoded by the nucleoredoxin-like 1 (NXNL1) gene which interrupts the metabolic and redox signaling between rods and cones. After providing scientific evidence supporting this mechanism, we propose a way to restore this lost signaling and prevent the cone vision loss in animal models of RP. We also explain how we could restore this signaling to prevent cone vision loss in animal models of the disease and how we plan to apply this therapeutic strategy by the administration of both products of NXNL1 encoding the trophic factor RdCVF and the thioredoxin enzyme RdCVFL using an adeno-associated viral vector. We describe in detail all the steps of this translational program, from the design of the drug, its production, biological validation, and analytical and preclinical qualification required for a future clinical trial that would, if successful, provide a treatment for this incurable disease.

Keywords: adeno-associated viral vector; aerobic glycolysis; central vision; chemical manufacturing; clinical trial; cone photoreceptor; gene therapy; retinitis pigmentosa; rod-derived cone viability factor; thioredoxin signaling.

Figure 1

Subretinal injection of AAV-RdCVF-RdCVFL to prevent the loss of function of cones in retinitis pigmentosa, (A) Transduction of the drug (recombinant AAV) to the retinal pigmented epithelium, expression and secretion of RdCVF to stimulate glucose entry, cone outer segment renewal (CosR) and the pentose phosphate pathway (PPP). (B) Transduction of the drug (recombinant AAV) to the cones and stimulation of redox homeostasis through NADPH, reduced by the metabolism of glucose through the pentose phosphate pathway.