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Shu Kachi, Asako Matsui, Yasuki Fujii, Ai Kurotsuchi, Hiroko Terasaki; Unfolded Protein Response is Associated with Expression of Vascular Endothelial Growth Factor by Retinal Pigment Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):860.
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Amyloid beta up-regulates the expression of vascular endothelial growth factor (VEGF) by retinal pigment epithelial (RPE) cells. The purpose of this study was to determine whether this expression of VEGF is triggered by the unfolded protein response (UPR).
ARPE19 cells were cultured with 1, 10 or 25 µM amyloid beta. After 24 hours, the medium was changed to one with the amyloid beta and 2.5 µM 4-phenylbutyric acid (PBA). The cells were cultured for an additional 24 hours. The culture medium and the cells were collected, and ELISA for VEGF and western blotting for GAPDH and UPR markers were performed. Some cells were fixed and immunostained for GRP78/Bip.
The VEGF concentration in the culture medium was 1340, 1755, and 2345 pg/mL when ARPE-19 cells were stimulated by 1,10, and 25 µM, respectively, of amyoid beta. However, when cells were exposed to 2.5 mM PBA and 25 µM amyloid beta, the VEGF concentration was 741 pg/ml which was significantly lower than that cultured with 25 µM amyloid beta without PBA (P<0.05). The GADD153/CHOP and cleaved caspase 12 signals detected by western blotting became significantly stronger by addition of amyloid beta to the culture medium, and it was decreased by addition of PBA. The GRP78/Bip signal detected by immunostaining was increased by addition of amyloid beta to the culture medium and decreased by addition of PBA.
These findings indicate that UPR plays a role in the expression of VEGF from RPE cells stimulated by amyloid beta.
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