The importance of Bcl-xL in the survival of human RPE cells.

Purpose: In normal eyes and in diseases such as age-related macular degeneration (AMD) and proliferative vitreoretinopathy (PVR), retinal pigment epithelial (RPE) cell survival is critically important. Bcl-x(L) has been shown to be among the most highly expressed survival factors in cultured human RPE cells. In the current study the effect of Bcl-x(L) blockade on human RPE cell survival was determined under normal conditions and after induced oxidative stress.

Caspase-8-mediated apoptosis in human RPE cells.

Purpose: Tumor necrosis factor (TNF)-alpha is an important cytokine associated with age-related macular degeneration (AMD) and proliferative vitreoretinopathy (PVR). TNF-alpha activates the extrinsic apoptotic pathway. In many cells, nuclear transcription factor (NF)-kappaB upregulates antiapoptotic proteins and prevents TNF-alpha-mediated apoptosis.

Oxidant-mediated Akt activation in human RPE cells.

Purpose: To determine whether a model oxidant, hydrogen peroxide (H2O2), influences Akt activation and, if so, whether Akt activation promotes retinal pigment epithelial (RPE) cell survival.

Methods: Cultured human RPE cells were pretreated with medium alone, with LY294002 (LY), an inhibitor of phosphatidylinositol-3 kinase (PI3K) and its downstream effector Akt, or with Akt/protein kinase B signaling inhibitor (API)-2, a specific Akt inhibitor, and then were stimulated with H2O2 at different doses for various times. Akt phosphorylation was evaluated by Western blot using antibody against phosphorylated Akt (Ser473).

Human RPE expression of cell survival factors.

Purpose: To determine basal and tumor necrosis factor (TNF)-alpha-regulated expression of retinal pigment epithelial (RPE) cell survival factors and whether regulation is dependent on nuclear transcription factor (NF)-kappaB.

Methods: Cultured human RPE cells were infected with adenovirus encoding either mutant inhibitory (I)-kappaB or beta-galactosidase and treated with TNF-alpha for various times. Freshly prepared RPE/choroid and RPE samples were isolated from human donor eyes.