title: Upregulation of GADD45α 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-45α (GADD45α) expression was markedly upregulated. Transient knockdown of GADD45α partially attenuated light-damage-induced apoptosis in ARPE-19 cells, whereas GADD45α overexpression dramatically increased it. These results demonstrate the critical function of GADD45α in light-induced RPE cellular apoptosis. Quantitative reverse transcription-PCR and western blotting revealed that the upregulation of GADD45α was under direct control of p53. Moreover, treatment with Ly294002, an inhibitor of AKT phosphorylation, further promoted GADD45α 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 GADD45α expression. Collectively, our findings reveal that light irrigation induces human RPE cellular apoptosis through upregulation of GADD45α 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.
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: M-L
authors.initials: ML
authors.lastname: Gao
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: W-L
authors.initials: WL
authors.lastname: Deng
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: N
authors.initials: N
authors.lastname: Huang
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Wang
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: X-L
authors.initials: XL
authors.lastname: Lei
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: Z-Q
authors.initials: ZQ
authors.lastname: Xu
authors.affiliation: Tissue Culture Center, New York Eye and Ear Infirmary, New York Medical College , Valhalla, 10595 New York, USA.
authors.forename: D-N
authors.initials: DN
authors.lastname: Hu
authors.affiliation: China National Institute of Standardization , Beijing 100191, China.
authors.forename: J-Q
authors.initials: JQ
authors.lastname: Cai
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: F
authors.initials: F
authors.lastname: Lu
authors.affiliation: Lab for Stem Cells and Retinal Regeneration, Division of Ophthalmic Genetics, Institute for Stem Cell Research, The Eye Hospital of Wenzhou Medical University, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Public Health , Wenzhou 325027, China.
authors.forename: Z-B
authors.initials: ZB
authors.lastname: Jin