Abstract
Purpose: :
PRCD mutations are associated with retinitis pigmentosa (RP) in both dogs and humans. PRCD encodes for a small protein (54 amino acids) of unknown function. The purpose of this work is to characterize PRCD’s retinal function.
Methods: :
Myc-tagged PRCD expression construct was made and transfected into cultured cells to test for protein secretion. The p.C2Y mutation was inserted by site-directed mutagenesis. To identify PRCD-binding proteins we used the Ras-Recruitment system. Identified interactions were confirmed by co-immunoprecipitation (co-IP).
Results: :
The first 20 amino acids of PRCD appear to encode for a signal peptide, suggesting that PRCD is a secreted protein. To test this hypothesis we expressed a myc-tagged PRCD in cultured cells and used western blot analysis to test for the presence of the protein in both cell extracts and conditioned media. PRCD was found in both. Moreover, the p.C2Y mutation, which was found in both dogs and a human patient with RP, eliminated the secretion of PRCD from cells. Using the Ras-Recruitment system we identified two putative PRCD-binding proteins, including one which is involved in retinal degeneration and is important for the function of the retinal pigmented epithelium (RPE).
Conclusions: :
Our data suggest that PRCD functions in the retina as a secreted protein, since a mutation which eliminates its secretion leads to severe retinal degeneration. The identified PRCD-binding partner indicates that both proteins may act in a common pathway associated with RPE correct function. These findings shed a new light on PRCD function and the etiology of RP.
Keywords: retinal degenerations: cell biology