Background
Induction of glucose-regulated protein (GRP)-78 in the endoplasmic reticulum (ER) is a protective mechanism cells use to adapt
to ER stress. We evaluated the expression of GRP-78 and its regulation by an oxidant tert-butyl hydroperoxide (tBH) in human
retinal pigment epithelium (RPE) cells.
Methods
We used a carboxy-H2-DCFDA staining method to detect tBH-induced accumulation of reactive oxygen species (ROS) in RPE cells,
and analyzed the expression of GRP-78 in normal human fetal and adult retinas and in cultured human RPE cells by immunohistochemistry.
The effects of tBH (10–100 μM) on GRP-78 and on growth arrest and DNA damage inducible genes 153 (GADD153) protein and mRNA
expression were studied using Western blot and real-time polymerase chain reaction.
Results
Sections of fetal retinas were negative for GRP-78. Adult retinas showed moderate cytoplasmic GRP-78 staining in the RPE and
choroid. tBH-induced ROS accumulation in RPE cells showed partial colocalization with the ER. GRP-78 and GADD153 mRNA and
protein expression in cultured RPE cells were significantly upregulated by treatment with tBH.
Conclusion
tBH increases oxidative stress, increases accumulation of ROS in the ER, and upregulates expression of GRP-78 and GADD153.
This supports the connection between oxidative stress and ER stress, and suggests that GRP-78 may serve a protective role
in the RPE response to oxidative stress.
Keywords RPE - ER stress - Oxidative stress - GRP-78
There are no commercial financial relationships to declare.