Endoplasmic reticulum stress decreases mitochondrial membrane potential and upregulates PARK2 expression in corneal endothelium

Abstract

Purpose : It is reported that endoplasmic reticulum stress (ER stress) is related to the pathogenesis of Fuchs endothelial corneal dystrophy (FECD) and that ER stress is associated with mitochondrial dysfunction and membrane potential decrease generally followed by mitophagy upregulation. However, these mechanisms have not been adequately investigated in corneal endothelium so far. The purpose of this study is to examine the relationship between ER stress and mitochondrial change in corneal endothelium.

Methods : Corneal endothelial cell line, HCEnC-21T, was treated with ER stressor thapsigargin with the concentration of 1, 2.5, 5, or 10 uM for 6 hours. Mitochondrial membrane potential was measured by JC-10 assay. After appropriate concentration was decided, we performed qRT-PCR with the primers of ER stress markers (CHOP, GRP78), mitophagy related genes (PINK1, PARK2), and mitochondrial anti-apoptotic gene Bcl2.

Results : JC-10 assay showed 10μM of thapsigargin reduced mitochondrial membrane potential. Compared with the controls, relative mRNA expression levels (ΔΔCT) of CHOP (58.5-fold), GRP78 (2.4-fold) and PARK2 (32.4-fold) were increased in HCEnC-21T cells with treatment of 10μM thapsigargin for 6 hours.

Conclusions : ER stress induced by thapsigargin decreased mitochondrial membrane potential and increase in ER stress markers and mitophagy-related gene PARK2. This data indicates that ER stress leads to mitochondrial dysfunction seen in FECD.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.