Fibulin–3 gene mutation leads to upregulation of chaperone proteins and apoptosis in retinal pigment epithelium

Abstract

Abstract: : Purpose: To determine the molecular effects of R345W FBLN3 mutation in ARPE19 cells in vtro Methods:Wild–type and mutant fibulin–3 fusion proteins was generated from EGFP vector constructs. Transient transfections of these constructs were undertaken in cultured ARPE19 cells. GFP fluorescence was detectd by confocal microscopy. Changes in expression of caspase 6 and chaperone proteins were detected using immunofluorescence staining. Results: The wild–type construct was secreted, but mutant fibulin–3 was seen to accumulate with the endoplasmic reticulum. This was associated with upregulation of BiP, calnexin and caspase 6. Conclusions: The R345W FBLN3 mutation initiates an unfolded protein reasponse and caspase–dependant cell death in cultured RPE cells. This study identifies a novel mechanism that might explain why this mutation in humans leads to retinal drusen and macular degenereration.

Keywords: retinal pigment epithelium • retinal degenerations: hereditary • chaperones