Critical role of Rho-kinase and MEK/ERK pathways for angiotensin II-induced plasminogen activator inhibitor type-1 gene expression

Plasminogen activator inhibitor type-1 (PAI-1) plays an integral role not o nly in the regulation of fibrinolytic activity but also in the pathogenesis of atherosclerosis and hypertension. We investigated the signaling pathway s of angiotensin II (Ang II) leading to PAI-1 gene expression. Ang II incre ased the PAI-1 mRNA and protein levels in a time- and dose-dependent manner through the Ang II type 1 receptor in vascular smooth muscle cells. PAI-1 gene promoter activity measured by luciferase assay was significantly incre ased by Ang II. PAI-1 mRNA stability was also increased by Ang II. Ang II-i nduced PAI-1 mRNA upregulation was inhibited by BAPTA-AM, genistein, and AG 1478, suggesting that intracellular calcium, tyrosine kinase, and epidermal growth factor receptor transactivation are involved. Furthermore, PD98059, an inhibitor of extracellular signal-regulated kinase (ERK) kinase (MEK), almost completely suppressed Ang II-induced PAI-1 upregulation. Adenovirus- mediated overexpression of the dominant-negative form of Rho-kinase or Y276 32, a Rho-kinase inhibitor, also completely prevented PAI-1 induction by An g II without affecting Ang II-induced ERK activation. These data suggest th at activation of MEK/ERK and Rho-kinase pathways plays a pivotal role in PA I-1 gene upregulation by Ang II. The Rho-kinase pathway may be a novel targ et to inhibit Ang II signaling, and its inhibition may be useful in the tre atment of hypertension as well as atherosclerosis.