该研究探究了甜菜碱（BET）对人正常肝细胞LO2细胞中超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GPx）、过氧化氢酶（CAT）mRNA水平的影响及机制。使用实时荧光定量、蛋白质免疫印迹和酶联免疫吸附法检测细胞内抗氧化酶的mRNA水平，以及Nrf2-Keap1-ARE通路的相关指标。经不同浓度的BET处理12 h后，LO2细胞中SOD、GPx和CAT的mRNA水平显著提高，最高分别提高了1.08、0.51、0.88倍（p<0.05）；经250 μmol/L BET处理后，LO2细胞核中可与ARE区域结合的Nrf2蛋白水平和细胞内总的NRF2蛋白水平分别显著提高了1.21、0.80倍（p<0.05）；经Nrf2蛋白抑制剂鸦胆子苦醇处理后，BET对三种抗氧化酶mRNA水平的提高作用完全丧失；进一步地分析表明，BET并未显著提高Nrf2蛋白的mRNA和磷酸化水平，但将Keap1的mRNA和蛋白质水分别降低了38.21%和49.15%（p<0.05）。这些结果表明，BET可通过降低Keap1的水平激活Nrf2-Keap1-ARE通路，进而提高抗氧化酶的mRNA水平。

The present study investigated the effect of betaine (BET) on the mRNA levels of superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) in human normal hepatocyte LO2 cells and the mechanism. The mRNA levels of antioxidases and indicators involving Nrf2-Keap1-ARE pathway were detected by real-time fluorescence quantitative method, western blot and enzyme-linked immunosorbent assay. The mRNA levels of SOD, GPX and CAT in LO2 cells were significantly increased by 1.08, 0.51 and 0.88 times, respectively, after 12 h treatment with different concentrations of BET (p<0.05). After 250 μmol/L of BET treatment, the protein level of Nrf2, which can bind to the ARE region in the nucleus, and the total Nrf2 protein in cells were significantly increased by 1.21 and 0.80 fold, respectively (p<0.05).After treatment with brucopicol, the effect of BET on the mRNA levels of three antioxidant enzymes was completely abolished. Further analysis showed that BET did not significantly increase the mRNA and phosphorylation levels of Nrf2, but decreased the mRNA and protein content of Keap1 by 38.21% and 49.15%, respectively (p<0.05). These results indicate that BET activates the Nrf2-Keap1-ARE pathway by decreasing the level of Keap1, and thus enhances the expression of antioxidant enzymes.

中国博士后科学基金项目（2019M662931）