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A. Iriyama, Y. Yanagi, Y. Tamaki; Light Exposure Induces Wnt/β-catenin Mediated Epithelial-Mesenchymal Transition in RPE Cells. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4408.
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Recently, oxidative stress activated by light exposure has been considered in the pathogenesis of age-related macular degeneration (AMD). In this study, the effect of white light exposure on retinal pigment epithelium (RPE) cells was investigated.
Firstly, activation of the Wnt/β-catenin pathway was investigated by immunofluorescence and Western blot analysis using a human retinal pigment epithelial (ARPE-19 cells). Secondly, the expression of α-smooth muscle actin (α-SMA), vimentin, matrix metalloprotein 7 (MMP7) and zona occludens 1 (ZO-1) was investigated by means of RT-PCR. Concomittantly, the effect of white light exposure on the ability of phagocytosis of ARPE-19 cells was investigated.
In ARPE-19 cells, the exposure of white light induced the activation of Wnt/β-catenin pathway as revealed by immunofluorescence and Western blot analysis. The mRNA levels of α-SMA, vimentin and MMP7 increased 4, 2.5 and 5 fold, respectively, and that of ZO-1 decreased 0.8 fold after white light exposure. The effects of light exposure on the expression of α-SMA, vimentin and MMP7 genes diminished 1.6, 1.1 and 1.5 fold respectively, by siRNA against β-catenin. The phagocytotic ability of ARPE19 cells decreased 0.60 fold after light exposure. The impairment of the phagocytotic ability diminished (0.76 vs control) when siRNA was used against β-catenin.
White light exposure induced the activation of Wnt/β-catenin pathway and concomittant epithelial-to-mesenchymal transition (EMT) in RPE cells. The occurrence of EMT may contribute to the impairment of the phagocytotic ability.
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