Urokinase
From Biocrawler, the free encyclopedia.
Urokinase, also called urokinase-type Plasminogen Activator (uPA) is an enzyme (EC 3.4.21.73 (http://us.expasy.org/cgi-bin/nicezyme.pl?3.4.21.73)) used as a thrombolytic agent in the treatment of severe or massive deep venous thrombosis, pulmonary embolism, myocardial infarction, and occluded intravenous or dialysis cannulas. Recently, Alteplase has replaced urokinase as a thrombolytic drug in infarctation.
Urokinase was first isolated from human urine and identified as a proteolytic enzyme. Pysiologically, it is circulating in the blood stream and converts plasminogen into Plasmin, which is an important degrading enzyme (EC 3.4.21.7) of many proteins of blood plasma but specifically of fibrin clots. This process is termed fibrinolysis and as a drug, urokinase is acting through the same mechanisms. It is inhibited by plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2).
It has been found that expression of urokinase and PAI-1 are significantly elevated in tissue in numerous cancers and can thus serve as markers for identifying malignancy.
urokinase Receptor
When urokinase is bound to its cellular receptor, the GPI anchored uPA receptor or uPAR, its proteolytic activity is strongly increased. Additionally, through binding of urokinase to uPAR, cellular mitotic pathways are activated and migration of cells is enhanced. This effect of uPA is independent of its proteolytic activity.
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