Abstract
Purpose:
Glutathione S-transferase pi isoform (GSTP1) is an intracellular detoxification enzyme that catalyzes reduction of chemically reactive electrophiles and is a zeaxanthin-binding protein in the human macula. We have previously demonstrated that GSTP1 levels are decreased in human age-related macular degeneration (AMD) retina compared to normal controls. We also showed that GSTP1 levels parallel survival of human retinal pigment epithelial (RPE) cells exposed to UV light, and GSTP1 over-expression protects them against UV light damage. In the present study, we determined the dose-response effect of oxidative stress on GSTP 1 expression in the survival of human RPE cell exposed to hydrogen peroxide (H2 O2) and cigarette smoke component hydroquinone (HQ).
Methods:
Human RPE cell culture (ARPE-19) was maintained using established protocols. ARPE-19 cells were plated at sub-confluent density in six-well plates and grown to confluence. Cells were treated with H2O2 (50, 100, 200 μM) or HQ (50, 100, 200 μM) for 24 hours. Cell survival was measured using trypan blue exclusion assay. GSTP1 expression was assessed using Western blot analysis.
Results:
ARPE-19 cell viability decreased when exposed to increasing concentrations of H2O2 and HQ. The GSTP1 expression also decreased in response to both oxidants compared to untreated control.
Conclusions:
Oxidative stress correlates with survival of human RPE cells and modulates GSTP1 levels in ARPE-19 cells exposed to H2O2 and HQ. We will determine next if GSTP1 levels affect RPE cell survival subject to oxidative stress and may protect RPE cells against oxidative damages.
Keywords: 634 oxidation/oxidative or free radical damage •
514 enzymes/enzyme inhibitors •
701 retinal pigment epithelium