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 inhi bitor type 2 (PAI-2) genes are differentially regulated by 12-phorbol 13-my ristate 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 simu ltaneously induced by this agonist, The t-PA and PAI-2 gene promoters harbo ur a cAMP-response element (CRE) which influences the expression of both ge nes. We have compared the binding activity of nuclear factors that recognis e these CRE sites. We show that CREB (CRE binding protein) recognises each CRE and that the degree of constitutive Ser119-phosphorylated t-PA CRE-boun d 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 phosphorylat ed on Ser119 (pCI-CREBala119) 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 i n PMA-mediated induction of PAI-2 gene expression, whereas PMA-mediated sup pression of t-PA in HT-1080 cells requires a different process, (C) 2000 Fe deration of European Biochemical Societies. Published by Elsevier: Science B.V. All rights reserved.