Abstract
Excessive proliferation of vascular smooth muscle cells (VSMCs) contributes to vessel renarrowing after angioplasty. Here we investigated the transcriptional regulation of the cyclin A gene, a key positive regulator of S phase that is induced after angioplasty. We show that Ras-dependent mitogenic signaling is essential for the normal stimulation of cyclin A promoter activity and DNA synthesis in VSMCs. Overexpression of the AP-1 transcription factor c-fos can circumvent this requirement via interaction with the cAMP-responsive element (CRE) in the cyclin A promoter. Moreover, c-fos overexpression in serum-starved VSMCs results in the induction of cyclin A promoter activity in a CRE-dependent manner, and increased binding of endogenous c-fos protein to the cyclin A CRE precedes the onset of DNA replication in VSMCs induced by serum in vitro and by angioplasty in vivo. We also show that E2F function is essential for both serum- and c-fos-dependent induction of cyclin A expression. Taken together, these findings suggest that c-fos and E2F are important components of the signaling cascade that link Ras activity to cyclin A transcription in VSMCs. These studies illustrate a novel link between the transcriptional and cell cycle machinery that may be relevant to the pathogenesis of vascular proliferative disorders.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Activating Transcription Factor 2
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Angioplasty
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Animals
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Bromodeoxyuridine / metabolism
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Carrier Proteins*
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Cell Cycle Proteins*
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Cells, Cultured
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Cyclic AMP Response Element-Binding Protein / genetics
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Cyclic AMP Response Element-Binding Protein / metabolism
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Cyclin A / genetics*
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Cyclin A / metabolism
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DNA / metabolism
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DNA-Binding Proteins*
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E2F Transcription Factors
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Endothelium, Vascular / cytology
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Endothelium, Vascular / metabolism*
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Flow Cytometry
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Gene Expression Regulation
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Immunohistochemistry
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Luciferases / metabolism
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Male
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Muscle, Smooth / blood supply*
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Muscle, Smooth / metabolism*
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Promoter Regions, Genetic
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Proto-Oncogene Proteins c-fos / genetics
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Proto-Oncogene Proteins c-fos / metabolism
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Proto-Oncogene Proteins c-fos / physiology*
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Rats
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Rats, Sprague-Dawley
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Retinoblastoma-Binding Protein 1
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S Phase / genetics
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Signal Transduction / genetics
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Transcription Factor DP1
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Transcription Factors / genetics
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Transcription Factors / metabolism
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Transcription Factors / physiology*
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Transcription, Genetic
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ras Proteins / metabolism
Substances
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Activating Transcription Factor 2
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Carrier Proteins
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Cell Cycle Proteins
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Cyclic AMP Response Element-Binding Protein
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Cyclin A
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DNA-Binding Proteins
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E2F Transcription Factors
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Proto-Oncogene Proteins c-fos
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Retinoblastoma-Binding Protein 1
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Transcription Factor DP1
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Transcription Factors
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DNA
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Luciferases
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ras Proteins
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Bromodeoxyuridine