scholarly journals Induction of murine NAD(P)H:quinone oxidoreductase by 2,3,7,8-tetrachlorodibenzo-p-dioxin requires the CNC (cap n collar) basic leucine zipper transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2): cross-interaction between AhR (aryl hydrocarbon receptor) and Nrf2 signal transduction

2004 ◽  
Vol 377 (1) ◽  
pp. 205-213 ◽  
Author(s):  
Qiang MA ◽  
Krista KINNEER ◽  
Yongyi BI ◽  
Jefferson Y. CHAN ◽  
Yuet Wai KAN
Keyword(s):  
Transcription Factor ◽  
Protein Synthesis ◽  
Aryl Hydrocarbon Receptor ◽  
Phase Ii ◽  
Leucine Zipper ◽  
Related Factor ◽  
Nuclear Factor ◽  
Basic Leucine Zipper ◽  
Aryl Hydrocarbon ◽  
Inhibition Of Protein Synthesis

TCDD (2,3,7,8-tetrachlorodibenzo-p-dixoin) induces phase II drug-metabolizing enzyme NQO1 [NAD(P)H:quinone oxidoreductase; EC 1.6.99.2; DT-diaphorase] in a wide range of mammalian tissues and cells. Here, we analysed the molecular pathway mediating NQO1 induction by TCDD in mouse hepatoma cells. Inhibition of protein synthesis with CHX (cycloheximide) completely blocks induction of NQO1 by TCDD as well as the basal expression and induction by phenolic antioxidant tBHQ (2-t-butylbenzene-1,4-diol), implicating a labile factor in NQO1 mRNA expression. The inhibition is both time- and concentration-dependent, requires inhibition of protein synthesis, and occurs at a transcriptional level. Inhibition of NQO1 transcription by CHX correlates with a rapid reduction of the CNC bZip (cap ‘n’ collar basic leucine zipper) transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) through the 26 S proteasome pathway. Moreover, blocking Nrf2 degradation with proteasome inhibitor MG132 increases the amount of Nrf2 and superinduces NQO1 in the presence of TCDD or tBHQ. Finally, genetic experiments using AhR (aryl hydrocarbon receptor)-, Arnt (aryl hydrocarbon receptor nuclear translocator)- or Nrf2-deficient cells reveal that, while induction of NQO1 by TCDD depends on the presence of AhR and Arnt, the basal and inducible expression of NQO1 by either TCDD or tBHQ requires functional Nrf2. The findings demonstrate a novel role of Nrf2 in the induction of NQO1 by TCDD and provide new insights into the mechanism by which Nrf2 regulates the induction of phase II enzymes by both phenolic antioxidants and AhR ligands.

scholarly journals Induction of metallothionein I by phenolic antioxidants requires metal-activated transcription factor 1 (MTF-1) and zinc

2004 ◽  
Vol 380 (3) ◽  
pp. 695-703 ◽  
Author(s):  
Yongyi BI ◽  
Richard D. PALMITER ◽  
Kristi M. WOOD ◽  
Qiang MA
Keyword(s):  
Transcription Factor ◽  
Phase Ii ◽  
Leucine Zipper ◽  
Gene Promoter ◽  
Phenolic Antioxidants ◽  
Related Factor ◽  
Basic Leucine Zipper ◽  
Free Zinc ◽  
Genes Encoding ◽  
Transcription Factor 1

Phenolic antioxidants, such as tBHQ [2,5-di-(t-butyl)-1,4-hydroquinone], induce Mt1 (metallothionein 1) gene expression and accumulation of MT protein. Induction of Mt1 mRNA does not depend on protein synthesis, and correlates with oxidation–reduction functions of the antioxidants. In the present study, we analysed the biochemical pathway of the induction. Induction depends on the presence of MTF-1 (metal-activated transcription factor 1), a transcription factor that is required for metal-induced transcription of Mt1, but does not require nuclear factor erythroid 2-related factor 2, a tBHQ-activated CNC bZip (cap ‘n’ collar basic leucine zipper) protein, that is responsible for regulating genes encoding phase II drug-metabolizing enzymes. Moreover, tBHQ induces the expression of MRE-βGeo, a reporter gene driven by five metal response elements that constitute an optimal MTF-1 binding site. Reconstitution of Mtf1-null cells with MTF-1 restores induction by both zinc and tBHQ. Unlike activation of phase II genes by tBHQ, induction of Mt1 expression does not occur in the presence of EDTA, when cells are cultured in zinc-depleted medium, or in cells with reduced intracellular ‘free’ zinc due to overexpression of ZnT1, a zinc-efflux transporter, indicating that induction requires zinc. In addition, fluorescence imaging reveals that tBHQ increases cytoplasmic free zinc concentration by mobilizing intracellular zinc pools. These findings establish that phenolic antioxidants activate Mt1 transcription by a zinc-dependent mechanism, which involves MTF-1 binding to metal regulator elements in the Mt1 gene promoter.

scholarly journals Cloning of Nrf1, an NF-E2-related transcription factor, by genetic selection in yeast

1993 ◽  
Vol 90 (23) ◽  
pp. 11371-11375 ◽  
Author(s):  
J Y Chan ◽  
X L Han ◽  
Y W Kan
Keyword(s):  
Transcription Factor ◽  
Binding Sites ◽  
Leucine Zipper ◽  
Genetic Selection ◽  
Yeast Cells ◽  
Binding Motif ◽  
Related Factor ◽  
Transcriptional Activators ◽  
Basic Leucine Zipper ◽  
Related Transcription Factor

We have devised a complementation assay in yeast to clone mammalian transcriptional activators and have used it to identify a human basic leucine-zipper transcription factor that we have designated Nrf1 for NF-E2-related factor 1. Nrf1 potentially encodes a 742-aa protein and displays marked homology to the mouse and human NF-E2 transcription factors. Nrf1 activates transcription via NF-E2 binding sites in yeast cells. The ubiquitous expression pattern of Nrf1 and the range of promoters containing the NF-E2 binding motif suggest that this gene may play a role in the regulation of heme synthesis and ferritin genes.

scholarly journals Protective Effects of Maclurin against Benzo[a]pyrene via Aryl Hydrocarbon Receptor and Nuclear Factor Erythroid 2-Related Factor 2 Targeting

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1189
Author(s):  
Jangsoon Kim ◽  
See-Hyoung Park ◽  
Seyoung Yang ◽  
Sae Woong Oh ◽  
Kitae Kwon ◽  
...  
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Nuclear Translocation ◽  
Radical Scavenging ◽  
Luciferase Reporter ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Nuclear Factor ◽  
Response Element ◽  
Reporter Activity ◽  
Aryl Hydrocarbon

Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon formed during the incomplete combustion of organic matter, has harmful effects. Therefore, much research is ongoing to develop agents that can mitigate the effects of B[a]P. The aim of this study was to examine the effect of maclurin, one component of the branches of Morus alba L., on the B[a]P-induced effects in HaCaT cells, a human keratinocyte cell line. Maclurin treatment inhibited aryl hydrocarbon receptor (AHR) signaling as evidenced by reduced xenobiotic response element (XRE) reporter activity, decreased expression of cytochrome P450 1A1 (CYP1A1), and reduced nuclear translocation of AHR. The B[a]P-induced dissociation of AHR from AHR-interacting protein (AIP) was suppressed by maclurin. Maclurin also inhibited the production of intracellular reactive oxygen species (ROS) induced by B[a]P. In addition, the antioxidant property of maclurin itself was demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Furthermore, maclurin activated antioxidant response element (ARE) signaling through enhancement of ARE luciferase reporter activity and the expression of ARE-dependent genes including nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1). Nrf2 activation and its nuclear translocation were promoted by maclurin through p38 MAPK activation. These data indicate that maclurin had antagonistic activity against B[a]P effects through activation of Nrf2-mediated signaling and inhibition of AHR signaling and, suggesting its potential in protecting from harmful B[a]P-containing pollutants.

scholarly journals Functional and Placental Expression Analysis of the Human NRF3 Transcription Factor

2005 ◽  
Vol 19 (1) ◽  
pp. 125-137 ◽  
Author(s):  
Benoı̂t Chénais ◽  
Anna Derjuga ◽  
Wael Massrieh ◽  
Kristy Red-Horse ◽  
Valerie Bellingard ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Related Factor ◽  
Nuclear Factor ◽  
Basic Leucine Zipper ◽  
Transcriptional Activation Domain ◽  
Functional Studies ◽  
Recognition Element ◽  
Protein Levels

Abstract Members of the Maf protooncogene and cap’n’ collar families of basic-leucine zipper transcription factors play important roles in development, differentiation, oncogenesis, and stress signaling. In this study, we performed an in vivo protein-protein interaction screen to search for novel partners of the small Maf proteins. Using full-length human MAFG protein as bait, we identified the human basic-leucine zipper protein NRF3 [NF-E2 (nuclear factor erythroid 2)-related factor 3] as an interaction partner. Transfection studies confirmed that NRF3 is able to dimerize with MAFG. The resulting NRF3/MAFG heterodimer recognizes nuclear factor-erythroid 2/Maf recognition element-type DNA-binding motifs. Functional analysis revealed the presence of a strong transcriptional activation domain in the center region of the NRF3 protein. We found that NRF3 transcripts are present in placental chorionic villi from at least week 12 of gestation on through term. In particular, NRF3 is highly expressed in primary placental cytotrophoblasts, but not in placental fibroblasts. The human choriocarcinoma cell lines BeWo and JAR, derived from trophoblastic tumors of the placenta, also strongly express NRF3 transcripts. We generated a NRF3-specific antiserum and identified NRF3 protein in placental choriocarcinoma cells. Furthermore, we showed that NRF3 transcript and protein levels are induced by TNF-α in JAR cells. Our functional studies suggest that human NRF3 is a potent transcriptional activator. Finally, our expression and induction analyses hint at a possible role of Nrf3 in placental gene expression and development.

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