Induction of AP-1 binding to intron 1 of SP-A1 and SP-A2 is implicated in the phorbol ester inhibition of human SP-A promoter activity.
A deletional analysis of the SP-A1 promoter in NCI-H441 cells was performed to identify potential cis-acting elements involved in phorbol ester-mediated repression of human SP-A transcription. The phorbol ester TPA reduced SP-A1 and SP-A2 promoter activity to approximately 35% to 45% compared to that of control cells. The inhibitory effect of TPA was significantly reduced upon removal of the region +64/+394 relative to the SP-A1 transcription start site. Using NCI-H441 nuclear proteins, electromobility shift assay analysis showed that the intron region +309/+329 of SP-A1 and the corresponding region of SP-A2 formed sequence-specific DNA/protein complexes that were induced by TPA exposure. The region +318/+324 of SP-A1 contains sequences similar to a consensus AP-1 binding site, TGACTGA (TCACTGA for SP-A2), which when mutated (TGAGAGT) prevented the formation of the TPA-induced DNA/protein complex. The TPA-induced complex was supershifted in the presence of antibody against the Jun family of proteins, but not the Fos family of proteins. These results suggest that the binding of AP-1 or an AP-1--like factor to the first intron of SP-A1 and SP-A2 may be involved in the phorbol ester inhibition of human SP-A gene expression.
Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey 17033, USA.
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Hoover
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Pavlovic
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Floros
D001665:Binding Sites; D016384:Consensus Sequence; D004273:DNA, Neoplasm / Q000737:chemistry; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D007438:Introns; D011401:Promoter Regions, Genetic; D011510:Proteolipids / Q000378:metabolism*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C445842:SFTPA1 protein, human; C445843:SFTPA2 protein, human; D018808:Transcription Factor AP-1; D013755:Tetradecanoylphorbol Acetate