Tauber Sarah, Sieckmann Maria Katharina, Erler Katrin, Stahl Wilhelm, Klotz Lars-Oliver, Steinbrenner Holger
Institute of Nutritional Sciences, Nutrigenomics Section, Friedrich Schiller University Jena, D-07743 Jena, Germany.
Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, D-40001 Düsseldorf, Germany.
Antioxidants (Basel). 2021 Jan 23;10(2):167. doi: 10.3390/antiox10020167.
Selenoenzymes, whose activity depends on adequate selenium (Se) supply, and phase II enzymes, encoded by target genes of nuclear factor erythroid 2-related factor 2 (Nrf2), take part in governing cellular redox homeostasis. Their interplay is still not entirely understood. Here, we exposed HepG2 hepatoma cells cultured under Se-deficient, Se-adequate, or Se-supranutritional conditions to the Nrf2 activators sulforaphane, cardamonin, or diethyl maleate. Nrf2 protein levels and intracellular localization were determined by immunoblotting, and mRNA levels of Nrf2 target genes and selenoproteins were assessed by qRT-PCR. Exposure to electrophiles resulted in rapid induction of Nrf2 and its enrichment in the nucleus, independent of the cellular Se status. All three electrophilic compounds caused an enhanced expression of Nrf2 target genes, although with differences regarding extent and time course of their induction. Whereas Se status did not significantly affect mRNA levels of the Nrf2 target genes, gene expression of selenoproteins with a low position in the cellular "selenoprotein hierarchy", such as glutathione peroxidase 1 (GPX1) or selenoprotein W (SELENOW), was elevated under Se-supplemented conditions, as compared to cells held in Se-deficient media. In conclusion, no major effect of Se status on Nrf2 signalling was observed in HepG2 cells.
硒酶的活性取决于充足的硒（Se）供应，而由核因子红细胞2相关因子2（Nrf2）的靶基因编码的II期酶参与调节细胞氧化还原稳态。它们之间的相互作用仍未完全了解。在这里，我们将在缺硒、富硒或超营养硒条件下培养的HepG2肝癌细胞暴露于Nrf2激活剂萝卜硫素、小豆蔻明或马来酸二乙酯中。通过免疫印迹法测定Nrf2蛋白水平和细胞内定位，并通过qRT-PCR评估Nrf2靶基因和硒蛋白的mRNA水平。暴露于亲电试剂会导致Nrf2的快速诱导及其在细胞核中的富集，这与细胞的硒状态无关。所有三种亲电化合物均导致Nrf2靶基因的表达增强，尽管它们在诱导程度和时间进程方面存在差异。虽然硒状态对Nrf2靶基因的mRNA水平没有显著影响，但与在缺硒培养基中培养的细胞相比，在补充硒的条件下，细胞“硒蛋白等级”中地位较低的硒蛋白，如谷胱甘肽过氧化物酶1（GPX1）或硒蛋白W（SELENOW）的基因表达有所升高。总之，在HepG2细胞中未观察到硒状态对Nrf2信号传导有重大影响。
