Abstract
Purpose :
Central areolar choroidal dystrophy (CACD) is an inherited retinal disease primarily affecting the macula. The disease is strongly linked to mutations in PRPH2. However, the molecular mechanism underlying PRPH2-associated CACD remains largely unknown. This study aims to unravel the pathological mechanism by which a recurrent PRPH2 missense mutation causes CACD.
Methods :
HEK293T cells were transiently transfected with plasmids encoding wildtype or Arg142Trp mutant PRPH2. Western blot analysis was used to determine protein levels. Co-transfections of wildtype and mutant Arg142Trp plasmids, followed by co-immunoprecipitation were performed to study PRPH2 homodimer formation. To study subcellular localization, COS-1 cells were transiently transfected with PRPH2-wildtype or PRPH2-Arg142Trp plasmids. In addition, plasmids were stably transfected into IMCD3 cells. Immunocytochemistry (ICC) was used to determine the localization of PRPH2.
Results :
No differences in PRPH2 protein levels between PRPH2-wildtype and PRPH2-Arg142Trp conditions were observed. The PRPH2-Arg142Trp protein can still form homodimers with both wildtype and Arg42Trp proteins. In both COS-1 and IMCD3 cells, the wildtype PRPH2 protein spreads into the cytoplasm and partly localizes to the plasma membrane, while the PRPH2-Arg142Trp mutant protein tends to cluster around the nucleus, partially co-localizing with golgi/ER. Moreover, the mutant protein was found only at the base of the cilium, while wildtype protein was observed along the entire cilium.
Conclusions :
Our results show no differences in expression levels between PRPH2-wildtype and PRPH2-Arg142Trp proteins. Furthermore, PRPH2 homodimer formation still occurs under PRPH2-Arg142Trp conditions, ruling out aberrant expression levels and erroneous PRPH2 homodimer formation as mechanism underlying CACD. ICC results indicated a difference in subcellular localization between wildtype and mutant PRPH2, with a potential defect in ciliary localization. Further studies are needed to elucidate the mechanism underlying PRPH2-associated CACD.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.