Nrf2信号因子在镉所致HEK细胞氧化损伤中的作用

Role of the Nrf2 Signaling in the Oxidative Damage Induced by Cadmium in HEK Cells

目的研究Nrf2信号因子在镉所致人胚肾上皮(HEK)细胞氧化应激中的作用。方法取对数生长期HEK细胞,分别以终浓度为0、2.5、5、10、20μmol/L的氯化镉染毒24、48和72h后,收获细胞,采用荧光定量聚合酶链式反应法检测HEK细胞核因子NF-E2相关因子2(nuclear factor E2-related factor 2,Nrf2)mRNA相对表达水平,采用免疫印迹法检测HEK细胞Nrf2核蛋白相对翻译水平。结果 HEK细胞在染镉浓度为20μmol/L下作用48h,SOD活性和GSH-Px活性显著降低(均P<0.05),而作用至72h,GSH-Px活性则有所升高;10μmol/L和20μmol/L镉作用72h,MDA含量均显著高于同时间点对照组和同组24h时间点(均P<0.05)。在10μmol/L和20μmol/L镉作用48和72h,Nrf2mRNA相对表达水平均有显著变化(均P<0.05);在20μmol/L作用48和72h,Nrf2核蛋白相对翻译水平显著升高(均P<0.05)。在镉染毒浓度为20μmol/L下作用于HEK细胞72h时,HEK细胞内GSH-Px活性、MDA含量均与Nrf2核蛋白相对翻译水平呈正相关关系(均P<0.05)。结论镉在引起HEK细胞发生氧化应激反应的同时,还能通过诱导Nrf2信号因子的活化来抑制氧化应激损伤,其机制可能是通过促进抗氧化酶表达实现的。

Objective To explore the effects of nuclear factor E2-related factor 2（Nrf2）on the oxidative stress induced by cadmium chloride（CdC12 ）in human embryonic kidney epithelial（HEK）cells. Methods HEK cells in the exponential phase were incubated with a final concentration of 0,2. 5,5,10, or 20 μmol/L CdCl2 for 24,48 or 72 hours in vitro. After cells were harves- ted, the relative expression level of Nrf2 mRNA was detected by real-time polymerase chain reaction（real-time PCR）, and West- ern blotting was applied to measure the relative translation level of Nrf2 nuclear protein. Results The SOD activity and GSH- Px activity were significantly decreased in HEK cells after 48 h exposure to 20 μmol/L CdC12 （P〈0. 05） ,and the GSH-Px ac- tivity tended to increase at 72 h. The MDA content was significantly higher after 72 h exposure to 10 or 20 μmol/L CdC12 than in the control group at same time point and in 24 h CdC12 treatment group（P〈0.05）. There was a significant change in the relative expression level of Nrf2 mRNA at 10 or 20 μmol/L CdC12 for 48 or 72 h（P〈0.05）. The relative translocation level of Nrf2 nuclear protein was significantly increased in HEK cells treated with 20 〈mol/L CdC12 for 48 or 72 h（P%0.05）. After 72 h ex- posure to 20 〈mol/L CdC12, a positive correlation was found between the GSH-Px activity or MDA content and the relative translation level of Nrf2 nuclear protein in HEK cells（P〈0.05）. Conclusion Cadmium can inhibit the oxidative stress damage by inducing the activation of Nrf2 signaling factor while causing oxidative stress in HEK cells. The mechanism may involve the promotion of the expression of antioxidant enzymes.