Abstract
Overexpression of vascular endothelial growth factor (VEGF) is implicated in a number of diseases. It is therefore critical that mechanisms exist to strictly regulate VEGF expression. A hypoxia-responsive (HR) region of the VEGF promoter which binds the HIF-1 transcription factor is a target for many signals that up-regulate VEGF transcription. Repressors targeting the HIF-1 transcription factor have been identified but no repressors directly binding the HR promoter region had been reported. We now report a novel mechanism of repression of the VEGF HR region involving DNA binding. We find that single strand DNA-specific cold shock domain (CSD or Y-box) proteins repress the HR region via a binding site downstream of the HIF-1 site. The repressor site is functional in unstimulated, normoxic fibroblasts and represents a novel means to prevent expression of VEGF in the absence of appropriate stimuli. We characterized complexes forming on the VEGF repressor site and identified a previously unreported nuclear CSD protein complex containing dbpA. Nuclear dbpA appears to bind as a dimer and we determined a means by which nuclear CSD proteins may enter double strand DNA to bind to their single strand sites to bring about repression of the VEGF HR region.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3T3 Cells
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Animals
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Base Sequence
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Binding Sites
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CCAAT-Enhancer-Binding Proteins / metabolism
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Cell Hypoxia
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Cell Nucleus / metabolism
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DNA, Single-Stranded / metabolism
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DNA, Superhelical / metabolism
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DNA-Binding Proteins / metabolism*
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Dimerization
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Endothelial Growth Factors / biosynthesis
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Endothelial Growth Factors / genetics*
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Fibroblasts / metabolism
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Gene Silencing*
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Heat-Shock Proteins / metabolism*
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Intercellular Signaling Peptides and Proteins / biosynthesis
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Intercellular Signaling Peptides and Proteins / genetics*
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Lymphokines / biosynthesis
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Lymphokines / genetics*
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Macromolecular Substances
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Mice
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Mice, Inbred BALB C
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Molecular Sequence Data
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NFI Transcription Factors
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Promoter Regions, Genetic*
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Repressor Proteins / metabolism*
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Silencer Elements, Transcriptional
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Transcription Factors*
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Transcriptional Activation
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors
Substances
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CCAAT-Enhancer-Binding Proteins
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Csda protein, mouse
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DNA, Single-Stranded
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DNA, Superhelical
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DNA-Binding Proteins
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Endothelial Growth Factors
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Heat-Shock Proteins
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Intercellular Signaling Peptides and Proteins
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Lymphokines
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Macromolecular Substances
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NFI Transcription Factors
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Repressor Proteins
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Transcription Factors
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors