Transcription factor decoy for activator protein-1 (AP-1) inhibits high glucose- and angiotensin II-induced type 1 plasminogen activator inhibitor (PAI-1) gene expression in cultured human vascular smooth muscle cells

Aims/hypothesis. Multiple factors, including hyperglycaemia and angiotensin II (Ang II), stimulate plasminogen activator inhibitor-1 (PAI-1) gene expression in human vascular smooth muscle cells. This study tested the hypothesis that hyperglycaemia and Ang II stimulate PAI-1 gene expression through activator protein-1 (AP-1) binding sites. Methods. We evaluated the role of AP-1 in PAI-1 gene expression in human vascular smooth muscle cells under high D-glucose and Ang II stimulation using a double-stranded cis-element AP-I oligodeoxynucleotide (decoy ODN). Results. Activator protein 1 activity was stimulated by high glucose and Ang II treatment and the AP-1 decoy ODN, but not a mismatched decoy ODN, competed for AP-1 activity. The increase in PAI-1 expression by high glucose and Ang II was significantly attenuated by the AP-1 decoy ODN (p<0.05 or p < 0.01). The increase in PAI-1 expression by high glucose and Ang II action on AP-1 sites was also confirmed by promoter analysis of PAI-1. Activator protein 1 activation in response to either high glucose or co-stimulation with high glucose and Ang II was inhibited completely by calphostin C (a PKC inhibitor) and partially by genistein (a protein tyrosine kinase inhibitor). Conclusion/interpretation. This study shows that high glucose and Ang II stimulate PAI-1 expression through AP-1 binding sites. Signal transduction after AP-1 activation by both high glucose and Ang II largely depends on PKC activation. These data indicate an important role for AP-1 in PAI-1 expression.