Abstract
Prolonged treatment of 3T3-L1 adipocytes with 8-Br-cAMP decreases expression of GLUT4, the insulin-responsive glucose transporter. Expression of a promoter-reporter gene construct that contained 785 base pairs of 5'-flanking region of the murine GLUT4 gene was down regulated by 8-Br-cAMP (p < 0.001), whereas expression of constructs that contained 641 or 469 base pairs of 5'-flanking region was not. A reporter gene construct in which bases -706 to -676 were deleted was not repressed by 8-Br-cAMP, thereby identifying a 30 bp region as necessary for repression of the GLUT4 promoter by 8-Br-cAMP. Mutations in this regulatory element that disrupt binding of the transcription factor NF1 abolish the 8-Br-cAMP-induced repression of the gene. Although insulin and cAMP both repress the GLUT4 promoter through this cis-element, they appear to do this through different mechanisms, as treatment with 8-Br-cAMP does not induce the phosphorylation of NF1 that is induced by insulin treatment.
Copyright 1999 Academic Press.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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3T3 Cells
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8-Bromo Cyclic Adenosine Monophosphate / pharmacology*
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Adipocytes / cytology
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Adipocytes / drug effects
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Animals
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Base Sequence
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Colforsin / pharmacology
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DNA-Binding Proteins / metabolism*
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Down-Regulation / drug effects*
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Genes, Reporter / genetics
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Glucose Transporter Type 4
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Insulin / pharmacology
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Mice
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Monosaccharide Transport Proteins / genetics*
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Muscle Proteins*
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Mutation
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NFI Transcription Factors
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Nuclear Proteins / metabolism
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Oligonucleotides / genetics
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Oligonucleotides / metabolism
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Phosphorylation / drug effects
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Promoter Regions, Genetic / genetics*
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RNA, Messenger / analysis
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RNA, Messenger / genetics
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Response Elements / genetics
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Reverse Transcriptase Polymerase Chain Reaction
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Transcription Factors / metabolism*
Substances
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DNA-Binding Proteins
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Glucose Transporter Type 4
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Insulin
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Monosaccharide Transport Proteins
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Muscle Proteins
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NFI Transcription Factors
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Nuclear Proteins
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Oligonucleotides
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RNA, Messenger
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Slc2a4 protein, mouse
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Transcription Factors
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transcription factor nuclear factor 1
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Colforsin
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8-Bromo Cyclic Adenosine Monophosphate