The Role of TRiC-enhanced Actin Folding in Leber Congenital Amaurosis.

Abstract

Mutations in TCP-1 ring complex (TRiC) have been associated with Leber Congenital Amaurosis (LCA). TRiC is involved in protein folding and has 8 essential subunits including CCT5. Herein, we studied the retina of TRiC mutant zebrafish to evaluate the possible role of impaired actin and tubulin folding in LCA. The cct5 retina was histologically studied using Toluidine Blue staining as well as TUNEL, BrdU-labeling, and Phalloidin assays. Retinal organisation was assessed by quantification of the cellularity utilising DAPI. Laminar organization of cct5 retinas was intact. Enhanced apoptosis throughout the cct5 retina was not compensated by higher proliferation rates, leaving the cct5 retina smaller in size. Quantification of retinal layer cellularity demonstrated that specifically the numbers of the amacrine and the retinal ganglion cells were depleted, suggesting that the cct5 retina was not uniformly affected by the reduced actin folding. Whereas the current literature suggests that LCA is predominantly affecting retinal photoreceptor cells and the retinal pigment epithelium, cct5 analyses demonstrated the important role of folding of actin by TRiC, suggesting that cct5 is a useful tool to specifically analyze the role of F-actin filaments in the context of LCA.