Abstract
The aim of this study was to examine the effects of the phorbol ester O-tetradecanoylphorbol 13-acetate (TPA) and forskolin on delta-opioid receptor gene transcription. Treatment of NG108-15 cells with TPA (100 nM) for 48 h increased delta-opioid receptor mRNA levels, whereas different concentrations of forskolin induced a transient down-regulation of mRNA 5 h after treatment, followed by increased mRNA levels after 48 h. Reporter gene assays in transiently transfected NG108-15 cells in combination with electrophoretic mobility shift assays indicate that the increase of delta-opioid receptor mRNA after stimulation with TPA is mediated by transcription factor AP-1, which binds 355 bp upstream of the start codon within the gene promoter. The forskolin-induced mRNA increase is mediated neither by a cyclic AMP-response element nor indirectly by AP-1 up-regulation. Reporter gene assays, mutational analysis, and electrophoretic mobility shift assays revealed that delta-opioid receptor gene regulation by forskolin is mediated by transcription factor AP-2, which binds to an element 157 bp upstream of the start codon.
MeSH terms
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1-Methyl-3-isobutylxanthine / pharmacology
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Aged
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Animals
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Carcinogens / pharmacology
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Colforsin / pharmacology
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Cyclic AMP-Dependent Protein Kinases / metabolism
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DNA-Binding Proteins / metabolism*
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Gene Expression Regulation, Enzymologic / drug effects
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Gene Expression Regulation, Enzymologic / physiology
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Genetic Complementation Test
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Glioma
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Humans
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Mice
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Phosphodiesterase Inhibitors / pharmacology
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Promoter Regions, Genetic / drug effects
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Promoter Regions, Genetic / physiology
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Protein Kinase C / metabolism
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RNA, Messenger / metabolism
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Receptor Cross-Talk / physiology
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Receptors, Opioid, delta / genetics*
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Tetradecanoylphorbol Acetate / pharmacology
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Transcription Factor AP-1 / metabolism*
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Transcription Factor AP-2
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Transcription Factors / metabolism*
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Transcription, Genetic / physiology*
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Tumor Cells, Cultured
Substances
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Carcinogens
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DNA-Binding Proteins
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Phosphodiesterase Inhibitors
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RNA, Messenger
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Receptors, Opioid, delta
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Transcription Factor AP-1
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Transcription Factor AP-2
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Transcription Factors
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Colforsin
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Cyclic AMP-Dependent Protein Kinases
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Protein Kinase C
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Tetradecanoylphorbol Acetate
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1-Methyl-3-isobutylxanthine