Interaction of Fibrin(ogen) with the Endothelial Cell Receptor VE- Cadherin: Localization of the Fibrin-Binding Site within the Third

Interaction of fibrin with endothelial cells through their receptor VE-cadherin has been implicated in modulation of angiogenesis and inflammation. Previous studies identified the VE-cadherin-binding site in the fibrin βN-domains formed by the NH2-terminal regions of fibrin β chains, and revealed that the recombinant dimeric (β15-66)2 fragment mimicking these domains preserves the VE-cadherin-binding properties of fibrin. To test if the other fibrin(ogen) regions/domains are involved in this interaction and localize the complementary fibrin-binding site in VE-cadherin, we prepared several recombinant fragments containing individual extracellular domains of VE-cadherin or combinations thereof, as well as several fragments corresponding to various fibrin(ogen) regions, and tested the interactions between them by ELISA and surface plasmon resonance. The experiments revealed that the βN-domains are the only fibrin(ogen) regions involved in the interaction with VE-cadherin. They also localized the fibrin-binding site to the third extracellular domain of VE-cadherin and established that the fibrin-binding properties of this domain are not influenced by the presence or absence of the neighboring domains. In addition, the experiments confirmed that calcium ions, which are required to maintain proper conformation an