MOLECULES IN FOCUS - THROMBIN

Thrombin is a multifunctional serine protease which plays a central ro le in haemostasis by regulating platelet aggregation and blood coagula tion. It is formed from its precursor prothrombin following tissue inj ury and converts fibrinogen to fibrin in the final step of the clottin g cascade. It also promotes numerous cellular effects including chemot axis, proliferation. extracellular matrix turnover and release of cyto kines. These actions of thrombin on cells have been implicated in tiss ue repair processes and in the pathogenesis of inflammatory and fibrop roliferative disorders such as pulmonary fibrosis and atherosclerosis. Thrombin mediates its cellular effects by proteolytically activating cell surface receptors. Presently, two such receptors have been descri bed and their roles in regulation of these functions are currently bei ng investigated. The discovery of multiple thrombin receptors creates the possibility of selective receptor blockade of specific thrombin me diated events. New drugs with these actions should add to our current repertoire of thrombin inhibitors used to treat thrombotic diseases. ( C) 1998 Published by Elsevier Science Ltd. All rights reserved.