Medical School, Nanjing University, Nanjing, China.
Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.
J Biochem Mol Toxicol. 2024 Nov;38(11):e70031. doi: 10.1002/jbt.70031.
Ultraviolet (UV) radiation-triggered production of reactive oxygen species (ROS) is a primary contributor to apoptosis in human lens epithelial cells (HLECs), which can ultimately result in cataract formation. The nuclear factor erythroid-2-related factor 2 (Nrf2)-Kelch ECH associating protein 1 (Keap1) pathway, a fundamental oxidative stress regulation mechanism, plays a crucial role in the development of cataracts. Ferulic acid (FA), recognized for its potent antioxidant properties can activate the Nrf2 signaling pathway to mitigate oxidative damage and cell apoptosis. In this study, we have demonstrated the protective effects of FA in reducing UVA-induced oxidative damage and apoptosis in HLECs through the modulation of the Keap1/Nrf2 pathway, as evidenced by both cellular and animal experiments. HLECs and Lens were exposed to 10 J/cm UVA radiation with or without prior treatment with FA. We found that UVA radiation increased oxidative damage and cell apoptosis in HLECs, ultimately leading to opacification of rat lenses, while FA was able to attenuate both oxidative damage and cell apoptosis in HLECs and reduce the degree of lens opacification. FA upregulated the expression of antioxidant response factors of the Keap1/Nrf2 pathway and downregulated the expression of apoptosis-related genes in HLECs, as demonstrated by Western blot and RT-qPCR analyses. We also found that UVA radiation increased the degree of demethylation of the Keap1 promoter in HLECs, whereas FA reduced the level of Keap1 promoter demethylation as determined by DNA sequencing. Additionally, UVA upregulated the expression of DNA active demethylase of the Keap1 promoter in HLECs, Dnmt1, Dnmt3a, and Dnmt3b, as shown by immunofluorescence, Western blot, and RT-qPCR, however, FA attenuated the activity of the passive demethylase TET1 in addition to the active demethylases. These results demonstrated that UVA radiation can cause oxidative damage, cell apoptosis, and rat lens opacification by increasing the demethylation of the Keap1 promoter in lens epithelial cells. Conversely, FA was shown to reduce oxidative damage, inhibit cell apoptosis, and decrease rat lens opacification by increasing the methylation of the Keap1 promoter. These findings suggest that FA could be therapeutically beneficial in preventing and mitigating cataracts induced by UVA radiation.
紫外线（UV）辐射引发的活性氧（ROS）产生是人类晶状体上皮细胞（HLEC）凋亡的主要原因，这最终可能导致白内障形成。核因子红细胞 2 相关因子 2（Nrf2）-Kelch ECH 相关蛋白 1（Keap1）途径是一种基本的氧化应激调节机制，在白内障的发展中起着至关重要的作用。阿魏酸（FA）因其强大的抗氧化特性而受到认可，它可以激活 Nrf2 信号通路，减轻氧化损伤和细胞凋亡。在这项研究中，我们通过细胞和动物实验证明，FA 通过调节 Keap1/Nrf2 通路，在减少 UVA 诱导的 HLEC 氧化损伤和凋亡方面具有保护作用。用或不用 FA 预处理后，将 HLEC 和 Lens 暴露于 10J/cm UVA 辐射下。我们发现 UVA 辐射增加了 HLEC 中的氧化损伤和细胞凋亡，最终导致大鼠晶状体混浊，而 FA 能够减轻 HLEC 中的氧化损伤和细胞凋亡，并降低晶状体混浊的程度。FA 上调了 HLEC 中 Keap1/Nrf2 通路的抗氧化反应因子的表达，并通过 Western blot 和 RT-qPCR 分析下调了凋亡相关基因的表达。我们还发现，UVA 辐射增加了 HLEC 中 Keap1 启动子的去甲基化程度，而 FA 则通过 DNA 测序降低了 Keap1 启动子去甲基化的水平。此外，UVA 上调了 HLEC 中 Keap1 启动子的 DNA 主动去甲基酶 Dnmt1、Dnmt3a 和 Dnmt3b 的表达，如免疫荧光、Western blot 和 RT-qPCR 所示，然而，FA 除了抑制被动去甲基酶 TET1 的活性外，还抑制了主动去甲基酶的活性。这些结果表明，UVA 辐射可以通过增加晶状体上皮细胞中 Keap1 启动子的去甲基化来引起氧化损伤、细胞凋亡和大鼠晶状体混浊。相反，FA 可以通过增加 Keap1 启动子的甲基化来减少氧化损伤、抑制细胞凋亡和降低大鼠晶状体混浊。这些发现表明，FA 可能具有治疗益处，可预防和减轻 UVA 辐射引起的白内障。
