Matrix metalloproteases (MMPs) play many important roles in normal and pathological remodeling processes including atherothrombotic disease, inflammation, angiogenesis and cancer. This invention relates to the activation of protease-activated receptor-1 (PAR-1) by endogenous platelet MMP-1 collagenase on the surface of platelets. Exposure of platelets to fibrillar collagen converts the surface-bound pro-MMP-1 zymogen to active MMP-1, which promotes aggregation through PAR-1, MMP-1 is shown to cleave the PAR-1 extracellular domain at a novel site, which then strongly activates Rho-GTP signaling pathways, cell shape change and motility, and MAPK signaling. Blockade of MMP-PAR 1 suppresses thrombogenesis under arterial flow conditions and inhibited thrombosis in animals. These studies provide a link between matrix-dependent activation of metalloproteases and platelet-G protein signaling and identify MMP- 1/PAR-1 as a new target for the treatment and prevention of arterial thrombosis and other thrombotic diseases.
