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T. Yoshikawa, N. Ogata, I. Hiroshi, S. Masamitsu, H. Hideaki, K. Takahashi; Altered Expression of Tight Junctions in Apre19 Cells Under Endoplasmic Reticulum Stress. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1404.
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© ARVO (1962-2015); The Authors (2016-present)
Endoplasmic reticulum (ER) stress has been linked to the pathogenesis of the several diseases,e.g.. diabetes mellitus and Parkinson disease. ER stress induces the expression of inflammatory cytokines, and inflammatory cytokines have been reported to be the leading cause of diabetic retinopathy (DR) and age-related macular degeneration (AMD). Because retinal pigment epithelial (RPE) cells are associated with the development and pathogenesis of DR and AMD, we investigated the expression of tight junctions, and angiogenic and /anti- angiogenic factors in RPE cells under ER stress in vitro.
ER stress was induced in cultured ARPE19 cells , a human retinal pigment epithelium cell line, by exposure to tunicamycin (TM; 1µg/ml) to inhibit N-linked glycosylation or thapsigargin (TG; 1µM) to inhibit the sarcoplasmic/endoplasmic calcium-ATPase. After 6, 12, 24, and 48 hours exposure, RNAs were extracted from the ARPE cells. The expressions of; GRP78/Bip (Bip) and C/EBP-homologous protein (CHOP) , markers of ER stress; zonula occluden (ZO)-1, occludin, and claudin1, genes for tight junctions; and vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF) were determined by real time RT-PCR.
The expressions of Bip and CHOP mRNAs were significantly increased in the ARPE 19 cells time dependently under ER stress induced by both TM and TG. The expression of CHOP was increased by forty-fold increase at 48 hrs compared to that of the controls. The expressions of ZO-1, occludin, and claudin1 were increased by TM and TG. In addition, the expression of VEGF mRNA was increased by both TM and TG. The expressions of mRNAs of VEGF and occludin increased in a time dependent way. The correlation between the degree of expression of VEGF and PEDF was not significant.
The increased expression of tight junctions and VEGF in TM- or TG-exposed ARPE19 cells indicate that the ER stress can alter the function of RPE cells and may be involved in the pathogenesis of DR and AMD.
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