Activation of thrombin-inactivated single-chain urokinase-type plasminogen activator by dipeptidyl peptidase I (cathepsin C).
Single-chain urokinase-type plasminogen activator (scu-PA) is inactivated by thrombin, which cleaves the peptide bond between Arg156 and Phe157. In a search for potential activators of thrombin-cleaved two-chain urokinase-type plasminogen activator (tcu-PA/T), we found that the lysosomal aminopeptidase dipeptidyl-peptidase I or cathepsin C efficiently activates tcu-PA/T. Cathepsin C was as active towards tcu-PA/T as the bacterial proteinase thermolysin and about 300-times more active than plasmin. The activation by cathepsin C proceeded in a concentration-dependent and time-dependent manner with a pH optimum between 5 and 7. Furthermore, the effect of cathepsin C was inhibited by cystatin and stimulated by cysteine, typical for the action of a thiol proteinase. As no degradation of the tcu-PA/T molecule by cathepsin C was visible on SDS/PAGE, we suggest that activation of tcu-PA/T occurs by cleavage between Lys158-Ile159 and removal of the two N-terminal amino acid residues (Phe157-Lys158) of the B chain of tcu-PA/T. We conclude that both thrombin and dipeptidyl-peptidases like cathepsin C might play a regulatory role in the plasminogen-plasmin system by inactivating scu-PA and activating tcu-PA/T, respectively.
Nauland
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Gaubius Laboratory TNO-PG, Leiden, The Netherlands.
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D020789:Cathepsin C; D002461:Cell Line, Transformed; D015891:Cystatins / Q000494:pharmacology; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000494:pharmacology*; D004789:Enzyme Activation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007668:Kidney; D007700:Kinetics; D010084:Oxidation-Reduction; D013917:Thrombin / Q000494:pharmacology*; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors / Q000378:metabolism*
D015891:Cystatins; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D020789:Cathepsin C; D013917:Thrombin; D014568:Urokinase-Type Plasminogen Activator