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.
ABSTRACT. The aim of this study is to explore the effect of narrow band ultraviolet B (NB-UVB) on the chemokine receptor CCR6 mRNA levels in patients with psoriasis. Psoriasis area and severity index (PASI) values were recorded before and after the treatment with NB-UVB phototherapy of 30 psoriasis vulgaris patients. The reverse transcription-polymerase chain reaction method was used to detect the expression level of CCR6 mRNA in peripheral blood mononuclear cells, and compared with 30 healthy subjects. The PASI value of the 30 psoriasis vulgaris patients decreased significantly after 15 iterations of phototherapy treatment (P < 0.01). The expression level of CCR6 mRNA in psoriasis patients was significantly higher than in the healthy controls (P < 0.01), while the expression level of CCR6 mRNA decreased significantly after phototherapy (P < 0.01). Reduction of CCR6 level may be one of the mechanisms through which NB-UVB can treat psoriasis.
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