Von Willebrand factor (vWF) is a constitutive and specific component of endothelial cell (EC) matrix. In this paper we show that, in vitro, vWF can induce EC adhesion and promote organization of microfilaments and adhesion plaques. In contrast, human vascular smooth muscle cells and MG63 osteosarcoma cells did not adhere and spread on vWF. Using antibodies to the β chains of fibronectin (β1) and vitronectin (β3) receptors it was found that ECs adherent to vWF show clustering of both receptors. The β1 receptor antibodies are arranged along stress fibers at sites of extracellular matrix contact while the β3 receptor antibodies were sharply confined at adhesion plaques. ECs release and organize endogenous fibronectin early during adhesion to vWF. Upon blocking protein synthesis and secretion, ECs can equally adhere and spread on vWF but, while the β3 receptors are regularly organized, the β1 receptors remain diffuse. This suggests that the organization of the β1 receptors depend on the release of fibronectin and/or other matrix proteins operated by the same cell. Antibodies to the β3 receptors fully block EC adhesion to vWF and detach ECs seeded on this substratum. In contrast, antibodies to the β1 receptors are poorly active. Overall these results fit with an accessory role of β1 receptors and indicate a leading role for the β3 receptors in EC interaction with vWF. To identify the EC binding domain on vWF we used monoclonal antibodies produced against a peptide representing the residues Glu1737-Ser1750 of the mature vWF and thought to be important in mediating its binding to the platelet receptor glycoprotein IIb-IIIa. We found that the antibody that recognizes the residues 1,744-1,746, containing the Arg-Gly-Asp sequence, completely inhibit EC adhesion to vWF whereas a second antibody recognizing the adjacent residues 1,740-1,742 (Arg-Gly-Asp-free) is inactive. Both antibodies do not interfere with EC adhesion to vitronectin. This defines the molecular domain on vWF that is specifically recognized by ECs and reaffirms the direct role of the Arg-Gly-Asp sequence as the intergrin receptor recognition site also in the vWF molecule.
CITATION STYLE
Dejana, E., Lampugnani, M. G., Giorgi, M., Gaboli, M., Federici, A. B., Ruggeri, Z. M., & Marchisio, P. C. (1989). Von Willebrand factor promotes endothelial cell adhesion via an Arg-Gly-Asp-dependent mechanism. Journal of Cell Biology, 109(1), 367–375. https://doi.org/10.1083/jcb.109.1.367
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