Protease nexin-1 interacts with thrombomodulin and modulates its anticoagulant effect.

Authors: Bouton, MC  Venisse, L  Richard, B  Pouzet, C  Arocas, V  Jandrot-Perrus, M 
Citation: Bouton MC, etal., Circ Res. 2007 Apr 27;100(8):1174-81. Epub 2007 Mar 22.
Pubmed: (View Article at PubMed) PMID:17379830
DOI: Full-text: DOI:10.1161/

The endothelial cell membrane glycoprotein thrombomodulin (TM) plays a critical role in the regulation of coagulation. TM is an essential cofactor in protein C activation by thrombin, and a direct inhibitor of thrombin-induced platelet activation and fibrinogen clotting. Protease nexin-1 (PN-1) is a serpin synthesized and secreted by a variety of cells including endothelial cells. PN-1 bound to the cell surface through interactions with glycosaminoglycans, is an efficient inhibitor of thrombin and controls thrombin-induced cell responses. An investigation of the interaction of PN-1 with TM using purified proteins and cultured human aortic endothelial cells was performed. Purified PN-1 was observed to bind to purified TM in a concentration-dependent manner. Double immunofluorescence studies indicated that PN-1 and TM were colocalized at the endothelial cell surface from which they were coprecipitated. Pretreatment of the cells with chondroitinase ABC greatly decreased the amount of the PN-1 associated to TM at the cell surface demonstrating the involvement of the TM chondroitin-sulfate chain in the formation of complexes. The inhibitory activity of the PN-1/TM complexes on the catalytic activity of thrombin, and on thrombin-induced fibrinogen clotting, was markedly enhanced when compared with the inhibitory activity of each partner. PN-1-overexpressing human aortic endothelial cells and PN-1-underexpressing human aortic endothelial cells exhibited respectively a significantly reduced ability and enhanced capacity to activate protein C. Furthermore, PN-1 decreased the cofactor activity of TM on thrombin activable fibrinolysis inhibitor activation by thrombin. These data show for the first time that PN-1 forms complexes with TM and modulates its anticoagulant activity.


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CRRD ID: 8553298
Created: 2014-05-08
Species: All species
Last Modified: 2014-05-08
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.