Factor VIIa and thrombin induce the expression of Cyr61 and connective tissue growth factor, extracellular matrix signaling proteins that could act as possible downstream mediators in factor VIIa center dot tissue factor-induced signal transduction

Extracellular interactions of plasma clotting factor VIIa (FVIIa) with tiss ue factor (TF) on cell surfaces trigger the intracellular signaling events. At present, it is unclear how these signals influence phenotype, To elucid ate this, we have used cDNA microarray technology to examine changes in tra nscriptional program in human fibroblasts in response to exposure to FVIIa. cDNA microarrays revealed that FVIIa binding to TF up-regulated the expres sion of Cyr61 and CTGF (connective tissue growth factor), the genes that en code extracellular matrix signaling proteins Cyr61 and CTGF, respectively. Northern blot analysis confirmed that FVIIa binding to TF markedly increase d the expression of Cyr61 and CTGF in a time- and dose-dependent manner. FV IIa catalytic activity is required for the gene induction, In addition to F VIIa, thrombin also induced the expression of Cyr61 and CTGF, Hirudin aboli shed the thrombin-induced expression of these mRNAs but not the FVIIa-induc ed expression. FVIIa-induced expression of Cyr61 appears not to involve the currently known protease-activated receptors (PARs), whereas thrombin-indu ced expression involves the activation of PAR1 and possibly an additional P AR. Various intracellular signaling pathway inhibitors exhibited different inhibitory pattern on FVIIa and thrombin-induced up-regulation of Cyr61. Cy r61 and CTGF could act as downstream mediators of FVIIa TF in affecting var ious biological processes.