Liu Xiaobin, Xavier Christy, Jann Jamieson, Wu Hongli
Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
Int J Mol Sci. 2016 Nov 3;17(11):1835. doi: 10.3390/ijms17111835.
Protein glutathionylation, defined as the formation of protein mixed disulfides (PSSG) between cysteine residues and glutathione (GSH), can lead to cell death. Glutaredoxin 1 (Grx1) is a thiol repair enzyme which catalyzes the reduction of PSSG. Therefore, Grx1 exerts strong anti-apoptotic effects by improving the redox state, especially in times of oxidative stress. However, there is currently no compound that is identified as a Grx1 activator. In this study, we identified and characterized Salvianolic acid B (Sal B), a natural compound, as a Grx1 inducer, which potently protected retinal pigment epithelial (RPE) cells from oxidative injury. Our results showed that treatment with Sal B protected primary human RPE cells from H₂O₂-induced cell damage. Interestingly, we found Sal B pretreatment upregulated Grx1 expression in RPE cells in a time- and dose-dependent manner. Furthermore, NF-E2-related factor 2 (Nrf2), the key transcription factor that regulates the expression of Grx1, was activated in Sal B treated RPE cells. Further investigation showed that knockdown of by small interfering RNA (siRNA) significantly reduced the protective effects of Sal B. We conclude that Sal B protects RPE cells against H₂O₂-induced cell injury through Grx1 induction by activating Nrf2 pathway, thus preventing lethal accumulation of PSSG and reversing oxidative damage.
蛋白质谷胱甘肽化被定义为半胱氨酸残基与谷胱甘肽（GSH）之间形成蛋白质混合二硫键（PSSG），可导致细胞死亡。谷氧还蛋白1（Grx1）是一种硫醇修复酶，催化PSSG的还原。因此，Grx1通过改善氧化还原状态发挥强大的抗凋亡作用，尤其是在氧化应激时期。然而，目前尚无被鉴定为Grx1激活剂的化合物。在本研究中，我们鉴定并表征了一种天然化合物丹酚酸B（Sal B）作为Grx1诱导剂，其能有效保护视网膜色素上皮（RPE）细胞免受氧化损伤。我们的结果表明，用Sal B处理可保护原代人RPE细胞免受H₂O₂诱导的细胞损伤。有趣的是，我们发现Sal B预处理能以时间和剂量依赖的方式上调RPE细胞中Grx1的表达。此外，调节Grx1表达的关键转录因子核因子E2相关因子2（Nrf2）在经Sal B处理的RPE细胞中被激活。进一步研究表明，用小干扰RNA（siRNA）敲低 可显著降低Sal B的保护作用。我们得出结论，Sal B通过激活Nrf2途径诱导Grx1，从而保护RPE细胞免受H₂O₂诱导的细胞损伤，防止PSSG的致命积累并逆转氧化损伤。
