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829 Folic acid protects melanocytes from oxidative damage by Keap1-Nrf2 pathway

      This study aims to investigate whether folic acid could protect human melanocyte against oxidative damage and to elucidate the underlying pharmacological mechanism. And we demonstrate that folic acid could protect melanocytes form oxidative damage. Folic acid is of great therapeutic potential in the treatment of vitiligo. Vitiligo is a common skin disease characterized by the loss of functional melanocytes. Previous studies have indicated that oxidative stress plays a pivotal role in the onset of vitiligo. Thus, antioxidant therapy is a promising therapeutic strategy to prevent or even reverse the progression of depigmentation. Folic acid is a conventional antioxidant, but whether folic acid can be used to treat vitiligo is unclear. PIG1 cells that are an immortalized human epidermal melanocyte cell line were cultured in Medium 254. H2O2 at 800 μM was chosen to induce oxidative stress. CCK8 assay was used to estimate the cell survival rate. Flow cytometry was used to measure the intracellular ROS level and apoptosis rate. The nuclear translocation of Nrf2 was tested by immunofluorescence. Western blot and qRT-PCR were used to analyze the mRNA and protein expression levels of Keap1, Nrf2, HO-1, SOD2 and NQO1. We initially found that folic acid was able to ameliorate H2O2-induced oxidative damage in human melanocytes. In parallel, folic acid lessened the accumulation of intracellular ROS by potentiating the activity of antioxidant enzymes. Furthermore, folic acid protected melanocyte against oxidative stress by activating Nrf2 and its downstream genes HO-1, SOD2 and NQO1, and interfering with Nrf2 diminished the protection of folic acid against H2O2-induced apoptosis. At last, the down-regulation of Keap1 contributed to the activation of Nrf2 induced by folic acid.