Palmitoylation of Progressive Rod-Cone Degeneration (PRCD) Regulates Protein Stability and Localization

Joseph Murphy,Saravanan Kolandaivelu

doi:10.1074/jbc.m116.742767

Joseph Murphy, Saravanan Kolandaivelu

Open Access

https://doi.org/10.1074/jbc.m116.742767

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Abstract

Progressive rod-cone degeneration (PRCD) is a photoreceptor outer segment (OS) disc-specific protein with unknown function that is associated with retinitis pigmentosa (RP). The most common mutation in PRCD linked with severe RP phenotype is substitution of the only cysteine to tyrosine (C2Y). In this study, we find that PRCD is post-translationally modified by a palmitoyl lipid group at the cysteine residue linked with RP. Disrupting PRCD palmitoylation either chemically or by genetically eliminating the modified cysteine dramatically affects the stability of PRCD. Furthermore, in vivo electroporation of PRCD C2Y mutant in the mouse retina demonstrates that the palmitoylation of PRCD is important for its proper localization in the photoreceptor OS. Mutant PRCD C2Y was found in the inner segment in contrast to normal localization of WT PRCD in the OS. Our results also suggest that zDHHC3, a palmitoyl acyltransferase (PAT), catalyzes the palmitoylation of PRCD in the Golgi compartment. In conclusion, we find that the palmitoylation of PRCD is crucial for its trafficking to the photoreceptor OS and mislocalization of this protein likely leads to RP-related phenotypes.

Highlights

Progressive rod-cone degeneration (PRCD) is a highly conserved small 53–54-amino acid residuelong protein [8, 9]
To test whether destabilization of the protein is a common mechanism behind PRCD-retinitis pigmentosa (RP), we examined the stability of another mutant V30M, which is linked with human RP [8]
Palmitoylation Is Important for Proper Targeting and Localization—We examined the localization of PRCD in the mouse retina using our custom-generated PRCD antibody and found that PRCD is localized in the photoreceptor outer segment (OS)

Summary

Introduction

PRCD is a highly conserved small 53–54-amino acid residuelong protein [8, 9]. So far, six mutations in PRCD are linked to RP in humans (8, 10 –12). Our results show that the PRCD WT transiently expressed into hRPE1 cells is palmitoylated (Fig. 2G, lane 3). C, immunoblot shows that inhibition of palmitoylation by 2-BP destabilizes the V30M mutant PRCD transiently transfected in hRPE1 cells.

Results

Conclusion