AIM: To evaluate the expression of uncoupling protein 2(UCP2) in a retinal pigment epithelium cell line(ARPE-19), under oxidative stress(OS).METHODS: ARPE-19 cells were divided into groups treated with various concentrations of hydrogen peroxide(H2 O2;0, 150, 300, 500, 700, and 900 μmol/L) for 24 h, to induce oxidative damage and cell viability was assessed by MTT assay. UCP2 mRNA expression in cells treated with H2 O2 was investigated by reverse transcription-polymerase chain reaction(RT-PCR). UCP2 protein expression was assessed by Western blotting and ROS levels analyzed by flow cytometry(FCM). Further, UCP2-siRNA treated cultures were exposed to H2 O2(0, 75, 150, and 300 μmol/L) for 2 h and cell viability determined by MTT assay.RESULTS: Cells treated with higher concentrations of H2 O2 appeared shrunken;their adhesion to adjacent cells was disrupted, and the number of dead cells increased. The results of cell viability assays demonstrated that the numbers of cells were decreased in a dose-dependent manner following treatment with H2 O2. Compared with untreated controls, cell viability was significantly reduced after treatment with >300 μmol/L H2 O2(P<0.05). Cell metabolic activity was decreased with increased concentrations of H2 O2 as detected by MTT assay. Levels of OS were further decreased in cells treated with UCP2-siRNA compared with those treated with H2 O2 alone(P<0.05). The results of RT-PCR and Western blotting demonstrated that UCP2 expression was reduced in H2 O2-treated groups compared with controls(P<0.05). FCM analysis showed that cell reactive oxygen species(ROS) levels were increased in H2 O2-treated groups and further upregulated by UCP2-si RNA treatment(P<0.05).CONCLUSION: Expression levels of UCP2 are decreased in ARPE-19 cells treated with H2 O2. ROS levels are further increased in cells treated with UCP2-siRNA relative to those treated with H2 O2 alone. UCP2 may have a protective role in ARPE-19 cells during oxidative injury.
