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Binding of factor VIIa to the endothelial cell protein C receptor reduces its coagulant activity
Author(s) -
LÓPEZSAGASETA J.,
MONTES R.,
PUY C.,
DÍEZ N.,
FUKUDOME K.,
HERMIDA J.
Publication year - 2007
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2007.02648.x
Subject(s) - endothelial protein c receptor , tissue factor , protein c , chemistry , factor vii , thrombomodulin , thrombin , serine protease , coagulation , factor x , biochemistry , protease , biology , immunology , enzyme , medicine , platelet
Summary. Background: Endothelial cell protein C receptor (EPCR) binds protein C through its γ‐carboxyglutamic acid (Gla) domain and enhances its thrombin–thrombomodulin complex‐dependent activation. So far, only protein C/activated protein C has been shown to interact with EPCR. Factor VII (FVII), the coagulation trigger upon tissue factor (TF) interaction, is a serine protease whose Gla domain is highly homologous to the Gla domain of protein C. Objectives: To characterize the binding of FVII/FVIIa to EPCR and its functional consequences. Methods and results: We demonstrated by surface plasmon resonance (SPR) that FVII/FVIIa binds to EPCR through its Gla domain. At therapeutic concentrations, FVIIa reduced the activation of protein C by 40%. Soluble EPCR (sEPCR) was also able to prolong dose‐dependently the clotting time induced by the FVIIa–TF complex. SPR and amidolytic experiments showed that FVIIa is able to interact simultaneously with TF and EPCR, thus ruling out the possibility that the effect of EPCR on clotting time was due to the inhibition of the binding between FVIIa and TF. sEPCR inhibited dose‐dependently the activation of FX by the FVIIa–TF complex. Notably, blocking the binding site of EPCR on the endothelial surface increased the generation of FXa 2‐fold. Conclusions: EPCR binds to FVII/FVIIa and inhibits the procoagulant activity of the FVIIa–TF complex.