Expression Analysis of Rho Gtpases in Different Mouse Models of Retinal Degenerations

Abstract

Purpose: : Small GTPase proteins of which Rac1, Cdc42 and RhoA have been studied extensively, represent a family of proteins which are best known for their crucial role in modulating the cytoskeleton. In addition, they also function as molecular switches for important signaling pathways in development, differentiation, apoptosis and survival. Relatively little information is available about the role of Rho GTPases in retinal physiology and pathophysiology. Here, we investigate Rho GTPases in connection with photoreceptor apoptosis in models of retinal degeneration.

Methods: : Retinas of VPP and rd1 mice were collected between postnatal days 1 and 52. Wild type 129S6 mice were exposed to 13klux of white light for 2 hours and retinas were analyzed between 1 and 10 days after exposure. Semi quantitative PCR, western blotting and immunohistochemical staining were used to analyze gene expression and protein localization in the retina.

Results: : Gene expression of the Rho GTPases and their effectors was unaltered during the degenerative processes in induced and inherited retinal degeneration. Total protein levels in light induced photoreceptor death also showed little fluctuations confirming the transcriptional data. Light exposure caused the accumulation of Cdc42 in the perinuclear stroma of TUNEL negative photoreceptors. Rac1 localized specifically to photoreceptor outer segments while antibodies against RhoA labeled the ganglion cell layer

Keywords: cytoskeleton • degenerations/dystrophies • retinal degenerations: cell biology