Distinct Roles of Nrf1 and Nrf2 in Monitoring the Reductive Stress Response to Dithiothreitol (DTT)

Reziyamu Wufuer; Zhuo Fan; Jianxin Yuan; Ze Zheng; Shaofan Hu; Guiyin Sun; Yiguo Zhang

doi:10.3390/antiox11081535

Distinct Roles of Nrf1 and Nrf2 in Monitoring the Reductive Stress Response to Dithiothreitol (DTT)

Antioxidants (Basel). 2022 Aug 7;11(8):1535. doi: 10.3390/antiox11081535.

Authors

Reziyamu Wufuer^{1

2

3}, Zhuo Fan^{1

3}, Jianxin Yuan^{1

3}, Ze Zheng^{1

3}, Shaofan Hu^{1

2

3}, Guiyin Sun², Yiguo Zhang^{2

3}

Affiliations

¹ Bioengineering College, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China.
² Chongqing University Jiangjin Hospital, School of Medicine, Chongqing University, No. 725 Jiangzhou Avenue, Dingshan Street, Jiangjin District, Chongqing 402260, China.
³ The Laboratory of Cell Biochemistry and Topogenetic Regulation, College of Bioengineering and Faculty of Medical Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China.

Abstract

Transcription factor Nrf2 (nuclear factor, erythroid 2-like 2, encoded by Nfe2l2) 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 Nfe2l1) 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 (WT) and Nrf1α^-/- cell lines, but almost unaltered in Nrf2^-/-^Δ^TA or caNrf2^ΔN cell lines (with a genetic loss of transactivation or N-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 WT and Nrf2^-/-^ΔTA cells, but diminished in Nrf1α^-/- cells, along with no changes in caNrf2^ΔN cells. Consequently, Nrf1α^-/-, but not Nrf2^-/-^ΔTA or caNrf2^ΔN, 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 N-glycodomain and DNA-binding domain, respectively) are required for its protein stability and transcription activity.

Keywords: Nrf1; Nrf2; antioxidant; endoplasmic reticulum stress; oxidative stress; redox; reductive stress.

Abstract

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