Upregulation of GADD45? in light-damaged retinal pigment epithelial cells.

ABSTRACT: To better understand the molecular mechanisms responsible for light-induced damage in retinal pigmented epithelial (RPE) cells, we developed an automated device to recapitulate intense light exposure. When compared with human fibroblasts, ARPE-19 cells that had been exposed to blue-rich light-emitting diode-light of 10?000?Lux at 37?°C for 9?h displayed dramatic cellular apoptosis. Collectively, gene expression profiling and qPCR demonstrated that growth arrest and DNA damage-45? (GADD45?) expression was markedly upregulated. Transient knockdown of GADD45? partially attenuated light-damage-induced apoptosis in ARPE-19 cells, whereas GADD45? overexpression dramatically increased it. These results demonstrate the critical function of GADD45? in light-induced RPE cellular apoptosis. Quantitative reverse transcription-PCR and western blotting revealed that the upregulation of GADD45? was under direct control of p53. Moreover, treatment with Ly294002, an inhibitor of AKT phosphorylation, further promoted GADD45? gene transcription in both non-light and light-damaged ARPE-19 cells. Treatment also exacerbated RPE cellular apoptosis after light exposure, confirming that inhibition of Akt phosphorylation increases GADD45? expression. Collectively, our findings reveal that light irrigation induces human RPE cellular apoptosis through upregulation of GADD45? expression mediated through both the p53 and phosphatidylinositol 3-kinase-AKT signaling pathways. These results provide new insights into human retinal diseases elicited by light damage and open a new avenue for disease prevention and treatment.

SUBMITTER: Gao ML 

PROVIDER: S-EPMC4979445 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature