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Wen-Li Deng, Na Huang, Mei-Ling Gao, Zi-Bing Jin; AKT-GADD45α signaling-pathway is a key to light irrigation-induced apoptosis in human retinal pigment epithelium cells. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4217.
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© ARVO (1962-2015); The Authors (2016-present)
Exposure to white light leads to irreversible apoptosis in retinal pigment epithelial (RPE) cells, however, molecular mechanisms of white light-induced damage to RPE cells remain largely unclear. To elucidate these mechanisms, we developed an automated device to recapitulate intense light exposure and investigated the light-mediated molecular alterations in the human RPE cell line, ARPE-19.
The quantitative instrument, SmartLight2.0 is used to induce light-damaged ARPE-19 cells, then we test those cells’ mitochondrial membrane potential and cell viability .According to the results of gene expression profile and RT-PCR, we focus on the AKT and GADD45α.So we inhibit the AKT pathway , overexpress as well as knockdown GADD45α.
We found that AKT-GADD45α signaling pathway was significantly altered in the RPE cells after light exposure. Compared with human fibroblasts, ARPE-19 cells exposed to white light at 10000Lux and 37℃ for 4.5h displayed dramatic cellular apoptosis. Gene expression profile and real-time PCR collectively demonstrated that GADD45α expression was markedly upregulated, which correlated with AKT dephosphorylation, as demonstrated by Western blotting. Moreover, Ly294002, an inhibitor of AKT phosphorylation, further increased GADD45α expression and exacerbated RPE cellular apoptosis after light exposure, confirming a link between Akt signaling and GADD45α expression. Transient knockdown of GADD45α partly rescued apoptosis in the lighted ARPE-19 cells, and overexpression of GADD45α dramatically aggravated cellular apoptosis.
Collectively, our findings demonstrate a key role for AKT-GADD45α signaling in light-induced RPE cell apoptosis, providing new insights into human retinal diseases elicited by light damage and opening a novel avenue for disease prevention and treatment.
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