A Novel mechanism of ultraviolet-induced skin damage protection by visible red light: Enhancement of GADD45A-mediated DNA repair activity

UVB exposure induces deleterious effects on skin, such as sunburn, inflammation and skin aging through direct and indirect DNA damage and the generation of reactive oxygen species. The therapeutic effects of visible red light against photodamage on skin have been extensively investigated, but the underlying biological mechanisms remain poorly understood. This study aimed to elucidate the protective mechanism of visible red light which against UV-induced skin damage in terms of DNA excision repair of in normal human dermal fibroblasts. We observed that the physical activity of GADD45A and apurinic/apyrimidinic endonuclease 1 (APE1), which has critical role in base excision repair, was enhanced by visible red light. Moreover, UV-induced DNA damage was mitigated by visible red light in an APE1-dependent manner. On the basis of the decrease in the GADD45A-APE1 interaction in an activating transcription factor-2 (ATF2)-knockdown system, we suggest that GADD45A-mediated DNA repair upon visible red light exposure is modulated by ATF2. Our results demonstrated that the ATF2-modulated enhancement of GADD45A-mediated base excision repair is a potential protective mechanism of visible red light. Our study provides an important clue toward the elucidation of the mechanism of skin protection by visible red light against various skin damage resulting aging and wrinkles.