Binding of factor Vila to the endothelial cell protein C receptor reduces its coagulant activity
Binding of factor Vila to the endothelial cell protein C receptor reduces its coagulant activity
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DOI：
10.1111/j.1538-7836.2007.02648.x
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发表时间：
2007-09-01
影响因子：
10.4
通讯作者：
Hermida, J.
中科院分区：
文献类型：
--
作者：
Lopez-Sagaseta, J.;Montes, R.;Hermida, J.
背景：内皮细胞蛋白 C 受体 (EPCR) 通过其 γ-羧基谷氨酸 (Gla) 结构域结合蛋白 C，并增强其凝血酶-血栓调节蛋白复合物依赖性激活。到目前为止，只有蛋白 C/活化蛋白 C 已被证明与 EPCR 相互作用。因子 VII (FVII) 是组织因子 (TF) 相互作用时的凝血触发因子，是一种丝氨酸蛋白酶，其 Gla 结构域与蛋白质的 Gla 结构域高度同源。目的：表征 FVII/FVIIa 与 EPCR 的结合及其功能后果。方法和结果：我们通过表面等离子共振 (SPR) 证明 FVII/FVIIa 通过其 Gla 结构域与 EPCR 结合。在治疗浓度下，FVIIa 使蛋白 C 的活化降低了 40%。可溶性 EPCR (sEPCR) 还能够以剂量依赖性方式延长 FVIIa-TF 复合物诱导的凝血时间。 SPR和酰胺分解实验表明FVIIa能够同时与TF和EPCR相互作用，从而排除了EPCR对凝血时间的影响是由于抑制了FVIIa和TF之间的结合而导致的。 sEPCR 剂量依赖性地抑制 FVIIa-TF 复合物对 FX 的激活。值得注意的是，阻断内皮表面 EPCR 的结合位点使 FXa 的生成增加了 2 倍。结论：EPCR 与 FVII/FVIIa 结合并抑制 FVIIa-TF 复合物的促凝血活性。
Background: Endothelial cell protein C receptor (EPCR) binds protein C through its gamma-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. 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.