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Jessica K. Huang, Ping Yang, Glenn J. Jaffe; The Effect Of Bcl-xL On Oxidant-mediated Pro- And Anti-survival Factor Expression In Human RPE Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):873.
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Retinal pigment epithelial (RPE) cells are chronically exposed to oxidative stress, which can contribute to RPE cell dysfunction and diseases, such as age-related macular degeneration (AMD). Oxidants such a hydrogen peroxide (H202) can cause RPE cell injury, and can induce RPE cell apoptosis. The interactions between pro- and anti-survival factors are vital for RPE survival. We have previously shown that Bcl-xL is an important RPE cell survival protein. In the current study, we determined the role of Bcl-xL in H202-mediated pro- and anti-survival survival factor gene expression in human RPE cells.
Cultured RPE cells were transfected with two modified 2’-O-methoxyethoxy antisense oligonucleotides (ASOs): Bcl-xL mismatched control and Bcl-xL-specific. After 2 days post-transfection, RPE cells were stimulated with 150µM H202 for 6 hours. RNA and protein were harvested. mRNA expression and protein levels were determined by real-time reverse transcription PCR (qRT-PCR) and Western blot, respectively.
Cells transfected with Bcl-xL-specific ASO had reduced Bcl-xL gene expression and increased anti-survival factor Bax expression 3 days post-transfection. After cells were exposed to H202, expression of Bax was further upregulated and other anti-survival factors Bad and Bak were increased. Pro-survival factor expression of Bcl-xL, c-IAP1, c-IAP2, and Traf-1 remained low.
Oxidant exposure disrupts the balance between pro- and anti-survival factors by shifting it toward greater expression of anti-survival factors, an effect that is enhanced when Bcl-xL is inhibited. Because Bcl-xL is an important protector against RPE cell oxidant-mediated injury, pathological conditions in which Bcl-xL is decreased could render RPE cells more sensitive to oxidative stress.
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