Inhibition of VCP preserves retinal structure and function in autosomal dominant retinal degeneration

Abstract

Due to continuously high production rates of rhodopsin (RHO) and high metabolic activity, photoreceptor neurons are especially vulnerable to defects in proteostasis. A proline to histidine substitution at position 23 (P23H) leads to production of structurally misfolded RHO, causing the most common form of autosomal dominant Retinitis Pigmentosa (adRP) in North America. The AAA-ATPase valosin-containing protein (VCP) extracts misfolded proteins from the ER membrane for cytosolic degradation. Here, we provide the first evidence that inhibition of VCP activity rescues degenerating P23H rod cells and improves their functional properties in P23H transgenic rat and P23H knock-in mouse retinae, both in vitro and in vivo. This improvement correlates with the restoration of the physiological RHO localization to rod outer segments (OS) and properly-assembled OS disks. As a single intravitreal injection suffices to deliver a long-lasting benefit in vivo, we suggest VCP inhibition as a potential therapeutic strategy for adRP patients carrying mutations in the RHO gene.