Abstract The antioxidant response element (ARE) is a cis-acting enhancer sequence located in the region containing genes related to antioxidant and detoxification. Under oxidative stress, the induction of nuclear factor-E2-related factor 2 (Nrf2)/ARE is considered as a fundamental process involved in defending reactive oxygen species (ROS) and providing protection against toxic xenobiotics. In this study, we obtained seven antioxidant peptides from soft-shelled turtle and concluded that Glu-Asp-Tyr-Gly-Ala (EDYGA) is the most potent ARE-luciferase inducer. To gain fundamental insights into the role of EDYGA in oxidative stress, we evaluated the effects of EDYGA on the Nrf2/Keap1 system in HepG2 cells. The results revealed that EDYGA modulated the Nrf2/ARE pathway by enhancing Nrf2 level through the stabilization of Nrf2, which was accomplished by a decrease in the level of Keap1. These actions eventually led to an increase in nuclear Nrf2 accumulation and ARE-binding activity. Moreover, silencing Nrf2 markedly reduced ARE-driven activity induced by EDYGA. Docking results proved that glutamate residues of peptide EDYGA directly bind to Arg 415 of Kelch domain receptor pocke. The results were helpful in understanding the antioxidant activity of peptides from soft-shelled turtle which have potential to be used in foods and drugs as functional ingredients.

中文翻译：

---

Nrf2 和 Keap1 参与软壳龟化学预防剂肽激活抗氧化反应元件 (ARE)

摘要 抗氧化反应元件（ARE）是一种顺式作用增强子序列，位于含有抗氧化和解毒相关基因的区域。在氧化应激下，核因子-E2 相关因子 2 (Nrf2)/ARE 的诱导被认为是参与防御活性氧 (ROS) 和提供针对有毒外源性物质的保护的基本过程。在这项研究中，我们从甲鱼中获得了七种抗氧化肽，并得出结论，Glu-Asp-Tyr-Gly-Ala (EDYGA) 是最有效的 ARE-荧光素酶诱导剂。为了深入了解 EDYGA 在氧化应激中的作用，我们评估了 EDYGA 对 HepG2 细胞中 Nrf2/Keap1 系统的影响。结果表明，EDYGA 通过稳定 Nrf2 来提高 Nrf2 水平，从而调节 Nrf2/ARE 通路，这是通过降低 Keap1 的水平来实现的。这些行动最终导致核 Nrf2 积累和 ARE 结合活性的增加。此外，沉默 Nrf2 显着降低了 EDYGA 诱导的 ARE 驱动活动。对接结果证明肽EDYGA的谷氨酸残基直接与Kelch结构域受体口袋的Arg 415结合。研究结果有助于了解甲鱼肽的抗氧化活性，这些肽具有作为功能成分用于食品和药物的潜力。对接结果证明肽EDYGA的谷氨酸残基直接与Kelch结构域受体口袋的Arg 415结合。研究结果有助于了解甲鱼肽的抗氧化活性，这些肽具有作为功能成分用于食品和药物的潜力。对接结果证明肽EDYGA的谷氨酸残基直接与Kelch结构域受体口袋的Arg 415结合。研究结果有助于了解甲鱼肽的抗氧化活性，这些肽具有作为功能成分用于食品和药物的潜力。