MOLECULAR-INTERACTIONS BETWEEN THE UROKINASE RECEPTOR AND INTEGRINS IN THE VASCULATURE

Cell-cell and cell-ECM interactions are key events in morphogenic proc esses during developmental and reproductive phases, in immune defense, wound healing and tissue repair, or hemostasis. Their dysregulation p lays a major role in the pathophysiology of cardiovascular diseases (a therosclerosis, restenosis, thrombosis) or angiogenesis-driven tumor p rogression. Protease cascades such as the plasminogen activation syste m are linked to cell adhesion and migration. The urokinase-type plasmi nogen activator (uPA) as well as its receptor (uPAR) has been found in a complex with beta(1)-, beta(2)-, and beta(3)-integrins, thereby all owing mutual interactions and regulatory processes between cell adhesi on and proteolysis to occur. Moreover, both uPAR and PAI-1 are capable of binding to vitronectin, an adhesive extracellular matrix protein, that serves as ligand for vascular integrins in an RGD-dependent manne r. This short review will focus on the molecular and functional intera ctions between the uPAR system and vascular integrins and discuss cons equences for vascular cell functions.