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J. Chen, L. Wang, Y. Chen, S. Paul, J. Cai; Inhibition of the Phosphoinositol-3-Kinase (PI3K) Pathway Potentiates Oxidative Injury Induced by 4-Hydroxy-2-Nonenal (4-HNE) in RPE Cells. Invest. Ophthalmol. Vis. Sci. 2008;49(13):231.
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© ARVO (1962-2015); The Authors (2016-present)
4-HNE is a major lipid peroxidation product in the retina and the retinal pigment epithelium (RPE). The purpose of the study is to investigate how the PI3K pathway affects the antioxidant response in cultured RPE cells exposed to 4-HNE.
Cultured ARPE-19 cells were treated by different concentrations of 4HNE. The PI3K was inhibited by LY294002. Intracellular glutathione (GSH) was measured by HPLC. The transcriptional activity of NF-E2-related factor-2 (Nrf2) was detected by dual luciferase assay after transient transfection with reporter plasmids. Viability of RPE cells treated with different concentrations of HNE for 48h was assayed by flow cytometry. The mRNA level of glutamate cysteine ligase (GCL) was quantified by Real Time RT-PCR. Formation of HNE adduct on cathepsin D, a lysosomal aspartate protease, was measured by immunoprecipitation and Western blot analysis.
Treatment with 4-HNE increased Nrf2 activity and GSH synthesis in a dose-dependent manner in cultured RPE cells. The modulatory subunit of GCL was upregulated by 4-HNE. The antioxidant responses were largely abolished upon co-treatment with the PI3K inhibitor, LY294002. However, cell death caused by high concentration 4-HNE was not further increased by LY294002.
4-HNE induced an Nrf2-dependent antioxidant response in the RPE and this protective mechanism is dependent on the functions of the PI3K/Akt pathway.
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