Wufuer Reziyamu, Fan Zhuo, Yuan Jianxin, Zheng Ze, Hu Shaofan, Sun Guiyin, Zhang Yiguo
Bioengineering College, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China.
Chongqing University Jiangjin Hospital, School of Medicine, Chongqing University, No. 725 Jiangzhou Avenue, Dingshan Street, Jiangjin District, Chongqing 402260, China.
Antioxidants (Basel). 2022 Aug 7;11(8):1535. doi: 10.3390/antiox11081535.
Transcription factor Nrf2 (nuclear factor, erythroid 2-like 2, encoded by ) has been accepted as a key player in redox regulatory responses to oxidative or reductive stresses. However, relatively little is known about the potential role of Nrf1 (nuclear factor, erythroid 2-like 1, encoded by ) in the redox responses, particularly to reductive stress, although this 'fossil-like' factor is indispensable for cell homeostasis and organ integrity during the life process. Herein, we examine distinct roles of Nrf1 and Nrf2 in monitoring the defense response to 1,4-dithiothreitol (DTT, serving as a reductive stressor), concomitantly with unfolded protein response being induced by this chemical (also defined as an endoplasmic reticulum stressor). The results revealed that intracellular reactive oxygen species (ROS) were modestly increased in DTT-treated wild-type () and cell lines, but almost unaltered in or cell lines (with a genetic loss of transactivation or -terminal Keap1-binding domains, respectively). This chemical treatment also enabled the rate of oxidized to reduced glutathione (i.e., GSSG to GSH) to be amplified in and cells, but diminished in cells, along with no changes in cells. Consequently, , but not or , cell viability was reinforced by DTT against its cytotoxicity, as accompanied by decreased apoptosis. Further experiments unraveled that Nrf1 and Nrf2 differentially, and also synergistically, regulated DTT-inducible expression of critical genes for defending against redox stress and endoplasmic reticulum stress. In addition, we also identified that Cys342 and Cys640 of Nrf1 (as redox-sensing sites within its -glycodomain and DNA-binding domain, respectively) are required for its protein stability and transcription activity.
转录因子Nrf2（由编码的核因子，红系2样2）已被公认为是对氧化或还原应激进行氧化还原调节反应的关键因子。然而，尽管这种“类化石”因子在生命过程中对细胞稳态和器官完整性不可或缺，但关于Nrf1（由编码的核因子，红系2样1）在氧化还原反应，特别是对还原应激中的潜在作用，人们了解得相对较少。在此，我们研究了Nrf1和Nrf2在监测对1,4 - 二硫苏糖醇（DTT，作为一种还原应激源）的防御反应中的不同作用，同时该化学物质会诱导未折叠蛋白反应（也被定义为一种内质网应激源）。结果显示，在DTT处理的野生型（）和细胞系中，细胞内活性氧（ROS）适度增加，但在或细胞系中几乎没有变化（分别是转录激活或 - 末端Keap1结合域基因缺失）。这种化学处理还使和细胞中氧化型谷胱甘肽与还原型谷胱甘肽的比率（即GSSG与GSH）升高，但在细胞中降低，而细胞中无变化。因此，DTT增强了细胞活力，对抗其细胞毒性，同时细胞凋亡减少，而或细胞则不然。进一步的实验表明，Nrf1和Nrf2以不同且协同的方式调节DTT诱导的防御氧化还原应激和内质网应激的关键基因的表达。此外，我们还确定Nrf1的Cys342和Cys640（分别作为其 - 糖基结构域和DNA结合结构域内的氧化还原感应位点）对其蛋白质稳定性和转录活性是必需的。
