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 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 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.

The Nrf2 transcription factor contributes both to the basal expression of glutathione S-transferases in mouse liver and to their induction by the chemopreventive synthetic antioxidants, butylated hydroxyanisole and ethoxyquin

2000 ◽  
Vol 28 (2) ◽  
pp. 33-41 ◽  
Author(s):  
J. D. Hayes ◽  
S. A. Chanas ◽  
C.J. Henderson ◽  
M. McMahon ◽  
C. Sun ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Leucine Zipper ◽  
Gene Activation ◽  
Phenolic Antioxidants ◽  
Butylated Hydroxyanisole ◽  
Alternative Mechanism ◽  
Synthetic Antioxidants ◽  
Basic Leucine Zipper ◽  
Knock Out ◽  
Basal Expression

An overview is provided of the cancer chemo-prevention actions of phenolic antioxidants and 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline (ethoxyquin). These agents principally appear to exert their beneficial effects through induction of phase II drug-metabolizing enzymes such as glutathione S-transferase (GST). The requirement for oxidative metabolism of the synthetic antioxidants to carbonyl-containing compounds, including quinones, in order that they can induce gene expression is discussed. Previous work has shown that the basic leucine zipper transcription factor Nrf2 is involved in induction of GST by the phenolic antioxidant butylated hydroxyanisole (BHA). Evidence is provided from a mouse possessing a targeted disruption of the Nrf2 gene that, in murine liver, the transcription factor regulates basal expression of several class Alpha and class Mu GST subunits, but not class Pi GST. In the Nrf2 knock-out mouse, hepatic induction of class Alpha and class Mu GST by BHA and the synthetic antioxidant ethoxyquin is similarly impaired, suggesting that these agents affect gene activation by a related mechanism. Significantly, residual induction of GST by antioxidants is apparent in the Nrf2 mutant mouse, indicating the existence of an alternative mechanism of gene activation.

scholarly journals Modeling the global effect of the basic-leucine zipper transcription factor 1 (bZIP1) on nitrogen and light regulation in Arabidopsis

2010 ◽  
Vol 4 (1) ◽  
pp. 111 ◽  
Author(s):  
Mariana Obertello ◽  
Gabriel Krouk ◽  
Manpreet S Katari ◽  
Suzan J Runko ◽  
Gloria M Coruzzi
Keyword(s):  
Transcription Factor ◽  
Leucine Zipper ◽  
Light Regulation ◽  
Global Effect ◽  
Basic Leucine Zipper ◽  
Transcription Factor 1

scholarly journals A Pivotal Role of the Basic Leucine Zipper Transcription Factor bZIP53 in the Regulation of Arabidopsis Seed Maturation Gene Expression Based on Heterodimerization and Protein Complex Formation

2009 ◽  
Vol 21 (6) ◽  
pp. 1747-1761 ◽  
Author(s):  
Rosario Alonso ◽  
Luis Oñate-Sánchez ◽  
Fridtjof Weltmeier ◽  
Andrea Ehlert ◽  
Isabel Diaz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Complex Formation ◽  
Protein Complex ◽  
Leucine Zipper ◽  
Pivotal Role ◽  
Basic Leucine Zipper ◽  
Arabidopsis Seed ◽  
Protein Complex Formation

scholarly journals Molecular cloning of cellular genes encoding retinoblastoma-associated proteins: identification of a gene with properties of the transcription factor E2F.

1992 ◽  
Vol 12 (12) ◽  
pp. 5620-5631 ◽  
Author(s):  
B Shan ◽  
X Zhu ◽  
P L Chen ◽  
T Durfee ◽  
Y Yang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Mammalian Cells ◽  
Leucine Zipper ◽  
T Antigen ◽  
Transactivation Domain ◽  
Recognition Sequence ◽  
Cellular Genes ◽  
Genes Encoding ◽  
Associated Proteins ◽  
Transcription Factor E2f

The retinoblastoma protein interacts with a number of cellular proteins to form complexes which are probably crucial for its normal physiological function. To identify these proteins, we isolated nine distinct clones by direct screening of cDNA expression libraries using purified RB protein as a probe. One of these clones, Ap12, is expressed predominantly at the G1-S boundary and in the S phase of the cell cycle. The nucleotide sequence of Ap12 has features characteristic of transcription factors. The C-terminal region binds to unphosphorylated RB in regions similar to those to which T antigen binds and contains a transactivation domain. A region containing a potential leucine zipper flanked by basic residues is able to bind an E2F recognition sequence specifically. Expression of Ap12 in mammalian cells significantly enhances E2F-dependent transcriptional activity. These results suggest that Ap12 encodes a protein with properties known to be characteristic of transcription factor E2F.

Basic leucine zipper transcription factor OsbZIP16 positively regulates drought resistance in rice

Plant Science ◽  
2012 ◽  
Vol 193-194 ◽  
pp. 8-17 ◽  
Author(s):  
Hao Chen ◽  
Wei Chen ◽  
Junli Zhou ◽  
Hang He ◽  
Liangbi Chen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Drought Resistance ◽  
Leucine Zipper ◽  
Basic Leucine Zipper
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