Overexpression of a dominant negative CREB protein in HT-1080 cells selectively disrupts plasminogen activator inhibitor type 2 but not tissue-type plasminogen activator gene expression.
The tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 2 (PAI-2) genes are differentially regulated by 12-phorbol 13-myristate acetate (PMA) in HT-1080 fibrosarcoma cells. PMA transcriptionally down-regulates the t-PA gene in HT-1080 cells, while the PAI-2 gene is simultaneously induced by this agonist. The t-PA and PAI-2 gene promoters harbour a cAMP-response element (CRE) which influences the expression of both genes. We have compared the binding activity of nuclear factors that recognise these CRE sites. We show that CREB (CRE binding protein) recognises each CRE and that the degree of constitutive Ser119-phosphorylated t-PA CRE-bound CREB was greater than for PAI-2 CRE bound CREB. Stable transfection of HT-1080 cells with a plasmid containing a CREB that could not be phosphorylated on Ser119 (pCI-CREB(ala119)) did not influence PMA-mediated suppression of t-PA mRNA, but markedly impaired PMA-mediated induction of PAI-2 mRNA. Our results demonstrate that the Ser119 residue of CREB plays a crucial role in PMA-mediated induction of PAI-2 gene expression, whereas PMA-mediated suppression of t-PA in HT-1080 cells requires a different process.
Costa
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Monash University Department of Medicine, 5th Floor Clive Ward Centre, Box Hill Hospital, Arnold Street, Box Hill, Vic. 3128, Australia.
Shen
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Medcalf
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RL
D051786:Cyclic AMP Response Element Modulator; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005354:Fibrosarcoma; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D010768:Phosphoserine; D017396:Plasminogen Activator Inhibitor 2 / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D017396:Plasminogen Activator Inhibitor 2; D011994:Recombinant Proteins; D012097:Repressor Proteins; D051786:Cyclic AMP Response Element Modulator; D010768:Phosphoserine; D010959:Tissue Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate