Roll of skin antioxidant system in UV irradiation and epidermal morphogenesis/differentiation

紫外线（UV）辐射是参与皮肤过早老化的发病机制的最重要的环境因素之一，称为光老化。紫外线在光老化中的有害作用与活性氧的产生有关，细胞抗氧化剂的作用是防止紫外线引起的光老化的发生并降低其严重程度。转录因子Nrf2及其细胞质锚定蛋白Keap1是细胞抗氧化反应的中心调节因子。在这里，我们研究了Nrf2的作用。利用nrf2基因缺陷（nrf2-/-）小鼠进行光老化研究。我们的研究结果表明，uvb照射的nrf2-/-小鼠表现出加速的光老化，如粗皱纹形成，皮肤柔韧性丧失，表皮增厚，真皮上部细胞外基质沉积。此外，nrf2-/-小鼠皮肤对脂质过氧化产物4-羟基-2-壬烯醛的反应性增加，皮肤谷胱甘肽水平显著降低。这些发现表明Nrf2在抗uvb诱导的光老化中起重要作用。

Ultraviolet (UV) radiation is one of the most important environmental factors involved in the pathogenesis of premature skin aging, termed photoaging. The harmful effects of UV in photoaging are associated with the generation of reactive oxygen species, and cellular antioxidants act to prevent the occurrence and reduce the severity of UV-induced photoaging. The transcription factor Nrf2 and its cytoplasmic anchor protein, Keap1, are central regulators of the cellular antioxidant response. Here, we investigated the role of the Nrf2. Keap1 pathway in photoaging using nrf2 gene-deficient (nrf2-/-) mice. Our results indicated that UVB-irradiated nrf2-/-mice showed accelerated photoaging, such as coarse wrinkle formation, loss of skin flexibility, epidermal thickening, and deposition of extracellular matrix in the upper dermis. In addition, nrf2-/-mice also showed an increase in cutaneous reactivity for the lipid peroxidation product 4-hydroxy-2-nonenal and a significant decrease in cutaneous glutathione level. These findings indicate that Nrf2 plays the important role in the protection against UVB-induced photoaging.