Abstract
Plasminogen activator inhibitor 1 (PAI-1) is the main fibrinolysis inhibitor, and high plasma levels are associated with an increased risk for vascular diseases. Inflammatory cytokines regulate PAI-1 through a hitherto unclear mechanism. Using reporter gene analysis, we could identify a region in the PAI-1 promoter that contributes to basal expression as well as to tumor necrosis factor alpha (TNFalpha) induction of PAI-1 in endothelial cells. Using this region as bait in a genetic screen, we could identify Nur77 (NAK-1, TR3, NR4A1) as an inducible DNA-binding protein that binds specifically to the PAI-1 promoter. Nur77 drives transcription of PAI-1 through direct binding to an NGFI-B responsive element (NBRE), indicating monomeric binding and a ligand-independent mechanism. Nur77, itself, is transcriptionally up-regulated by TNFalpha. High expression levels of Nur77 and its colocalization with PAI-1 in atherosclerotic tissues indicate that the described mechanism for PAI-1 regulation may also be operative in vivo.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Arteriosclerosis / metabolism
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Binding Sites
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Cells, Cultured / drug effects
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Cells, Cultured / metabolism
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Consensus Sequence
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Electrophoretic Mobility Shift Assay
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Endothelium, Vascular / cytology
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Endothelium, Vascular / drug effects
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Endothelium, Vascular / metabolism
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Fluorescent Antibody Technique, Indirect
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Gene Expression Regulation / drug effects*
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Humans
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Nuclear Receptor Subfamily 4, Group A, Member 1
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Plasminogen Activator Inhibitor 1 / biosynthesis*
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Plasminogen Activator Inhibitor 1 / genetics
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Promoter Regions, Genetic / genetics*
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Protein Binding
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Receptors, Cytoplasmic and Nuclear
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Receptors, Steroid
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Reverse Transcriptase Polymerase Chain Reaction / methods
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Transcription, Genetic / drug effects
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Transcription, Genetic / genetics
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Transfection
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Tumor Cells, Cultured / drug effects
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Tumor Cells, Cultured / metabolism
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Tumor Necrosis Factor-alpha / pharmacology*
Substances
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DNA-Binding Proteins
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NR4A1 protein, human
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Nuclear Receptor Subfamily 4, Group A, Member 1
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Plasminogen Activator Inhibitor 1
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Receptors, Cytoplasmic and Nuclear
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Receptors, Steroid
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Transcription Factors
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Tumor Necrosis Factor-alpha