Abstract
Purpose: :
To determine whether glutathione S-transferase pi isoform (GSTP1) levels affect survival of retinal pigment epithelial (RPE) cells subject to damaging levels of light. 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.
Methods: :
Human RPE cell culture (ARPE-19) was maintained and transfected using established protocols. Lentiviral expression clones of GSTP1 and small-hairpin RNA (shRNA) against GSTP1 coding region were procured from Genecopoeia and OpenBiosystems, respectively. The control and transfected ARPE-19 cells were exposed to ultraviolet (UV) light for 30 minutes, and cell survival was measured using trypan blue exclusion assay.
Results: :
The ARPE-19 cells over-expressing GSTP1 showed higher survival rate compared to shRNA-treated or untreated control cells. The shRNA-treated ARPE-19 cells showed lower survival rate compared to untreated control cells. The GSTP1 levels in ARPE-19 cells were present in the following order: Over-expressing cells (highest) > untreated control ARPE-19 cells > shRNA-treated cells (lowest); and the cell survival rate upon light damage followed the same order.
Conclusions: :
GSTP1 levels affect survival of human retinal pigment epithelial (RPE) cells exposed to UV light. GSTP1 over-expression may protect against UV light damage.
Keywords: age-related macular degeneration • oxidation/oxidative or free radical damage • enzymes/enzyme inhibitors