Abstract
DNA methylation at HpaII (CmCGG) sites inhibits expression of a human proenkephalin-CAT fusion gene when it is transiently expressed in CV-1 cells or stably expressed in C6-glioma cells. The inhibitory effects of HpaII methylation have been mapped to a site within the human proenkephalin promoter located at position -72 relative to the start site of transcription. This region spans a cAMP and phorbol ester inducible enhancer and methylation at this position inhibits both basal transcription and transcription induced by either cAMP or TPA. The HpaII site is located within an element which binds the transcription factor AP-2. In vitro methylation at this HpaII site inhibits the binding of AP-2. These results suggest that CpG methylation inhibits proenkephalin gene expression by directly interfering with the binding of a positively acting transcription factor previously shown to be essential for maximal basal, cAMP, and TPA inducible transcription.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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5-Methylcytosine
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Base Sequence
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Cloning, Molecular
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Cytosine / analogs & derivatives
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Cytosine / metabolism
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DNA / metabolism
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / metabolism
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Deoxyribonuclease HpaII
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Deoxyribonucleases, Type II Site-Specific / metabolism
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Dinucleoside Phosphates / metabolism*
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Enkephalins / genetics*
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Gene Expression Regulation*
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Humans
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Methylation
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Molecular Sequence Data
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Promoter Regions, Genetic
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Protein Precursors / genetics*
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Restriction Mapping
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Transcription Factor AP-2
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Transcription Factors / genetics*
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Transcription Factors / metabolism
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Transcription, Genetic
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Tumor Cells, Cultured
Substances
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DNA-Binding Proteins
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Dinucleoside Phosphates
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Enkephalins
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Protein Precursors
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Transcription Factor AP-2
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Transcription Factors
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proenkephalin
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cytidylyl-3'-5'-guanosine
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5-Methylcytosine
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Cytosine
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DNA
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Deoxyribonuclease HpaII
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Deoxyribonucleases, Type II Site-Specific