Probing intercellular interactions between vascular endothelial cadherin pairs at single-molecule resolution and in living cells.

Vascular endothelial (VE) cadherin is the surface glycoprotein cadherin specific to the endothelium that mediates cell-cell adhesion and plays a major role in the remodeling, gating, and maturation of vascular vessels. To investigate the contribution of individual VE-cadherins to endothelial cell-cell interactions and investigate whether different classical cadherins display different kinetics and micromechanical properties, we characterize the binding properties of VE-cadherin/VE-cadherin bonds at single-molecule resolution and in living human umbilical vein endothelial cells (HUVECs). Our single-molecule force spectroscopy measurements reveal that type II VE-cadherin molecules form bonds that are less prone to rupture and display a higher tensile strength than bonds formed by classical type I neuronal (N) cadherin and epithelial (E) cadherin. The equilibrium lifetime of the VE-cadherin/VE-cadherin bond is significantly longer than formed by N-cadherin/N-cadherin bonds and E-cadherin/E-cadherin bonds. These results indicate that VE-cadherins form bonds that have kinetics and mechanical properties that are significantly different from those formed by classical type I cadherins, properties that are particularly well adapted to the barrier and adhesive functions of VE-cadherin in endothelial cell-cell junctions.