Abstract
The mechanism of heme oxygenase-1 (ho-1) gene activation by arsenite was examined. Arsenite-stimulated expression of a ho-1 promoter/luciferase chimera in a dose-dependent manner in mouse hepatoma (Hepa) cells. Mutation analyses identified the arsenite-responsive sequence as the stress-response element (StRE), which resembles the binding sites for the AP-1 superfamily of basic-leucine zipper factors. In electrophoretic mobility shift assays, up to seven specific StRE-protein complexes were routinely detected using extracts from untreated Hepa cells whereas a single complex was typically observed after treatment with arsenite. Antibody "supershift" experiments identified Nrf2, JunD, and ATF3 in control complexes and the amount of these factors increased significantly in the arsenite-induced complex. MafG, ATF2, FosB, and JunB were also detected in the arsenite complex. Activation of a StRE-dependent luciferase gene by arsenite was inhibited to varying degrees by dominant-negative mutants of Nrf2, MafK, c-Fos, and CREB but most strongly with the latter. Together, these results implicate multiple basic-leucine zipper transcription factors in ho-1 gene activation by arsenite.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Activating Transcription Factor 2
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Activating Transcription Factor 3
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Animals
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Arsenites / pharmacology*
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Bacterial Proteins / metabolism
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Binding Sites
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Cyclic AMP Response Element-Binding Protein / metabolism
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DNA-Binding Proteins / metabolism*
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Enhancer Elements, Genetic
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Gene Expression Regulation, Enzymologic / drug effects
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Heme Oxygenase (Decyclizing) / drug effects
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Heme Oxygenase (Decyclizing) / genetics*
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Heme Oxygenase-1
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Leucine Zippers*
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Liver Neoplasms, Experimental
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MafK Transcription Factor
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Membrane Proteins
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Mice
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NF-E2-Related Factor 2
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Nuclear Proteins / metabolism
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Proto-Oncogene Proteins c-fos / drug effects
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Proto-Oncogene Proteins c-fos / metabolism
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Proto-Oncogene Proteins c-jun / metabolism
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Response Elements
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Stress, Physiological
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Trans-Activators / metabolism*
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Transcription Factor AP-1 / metabolism
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Transcription Factors / metabolism
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Transcriptional Activation
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Tumor Cells, Cultured
Substances
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Activating Transcription Factor 2
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Activating Transcription Factor 3
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Arsenites
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Atf2 protein, mouse
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Bacterial Proteins
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Cyclic AMP Response Element-Binding Protein
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DNA-Binding Proteins
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Fosb protein, mouse
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MafK Transcription Factor
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Membrane Proteins
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NF-E2-Related Factor 2
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Nfe2l2 protein, mouse
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Nuclear Proteins
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Proto-Oncogene Proteins c-fos
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Proto-Oncogene Proteins c-jun
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Trans-Activators
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Transcription Factor AP-1
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Transcription Factors
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Heme Oxygenase (Decyclizing)
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Heme Oxygenase-1
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Hmox1 protein, mouse
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arsenite