Abstract
Purpose: :
We have previously shown that oxidative stress (OS) can quantitatively regulate AP-1 gene expression changes in the human retinal pigment epithelium (RPE). The purpose of this study was to determine whether these molecular responses to quantified levels of OS can be modulated by pretreatment with vitamin A.
Methods: :
Confluent ARPE-19 cells were cultured for three days in defined media in the presence of vitamin A (0 - 100µM), and then treated with 500µM H2O2. RNA was isolated using a no-rinse method at 0-,1-,4-,8-, and 24-hours after OS and compared to untreated controls at each time point. FosB, cFos, JunB, ATF3, and EGR2 gene expression was determined by real-time PCR.
Results: :
Dose-dependent reductions in the level of transcription of FosB, cFos, ATF3 and JunB were seen following OS, after pretreatment with 20µM vitamin A, but not at lower doses. FosB transcription was reduced 3-fold and cFos transcription was reduced 4-fold compared to the controls at the 1-, 4-, and 8-hour time points. Pretreatment with doses of vitamin A greater than 40µM was toxic to the RPE cells in culture.
Conclusions: :
These studies show that pretreatment of RPE cells with vitamin A at a dose of 20µM optimally protects the cells from OS responses, using FosB and cFos transcriptional responses as biomarkers for OS.
Keywords: gene/expression • retinal pigment epithelium • oxidation/oxidative or free radical damage