Glycoprotein Ib can mediate endothelial cell attachment to a von Willebrand factor substratum
Beacham, D.A.; Cruz, M.A.; Handin, R.I.
Thrombosis and Haemostasis 73(2): 309-317
1995
ISSN/ISBN: 0340-6245 PMID: 7792748 Document Number: 446901
Introduction of single amino acid substitutions into the C-terminal Arg-Gly-Asp-Ser (RGDS) site of von Willebrand Factor. referred to as RGD mutant vWF, selectively abrogated vWF binding to platelet glycoprotein IIb/IIIa (GpIIb/IIIa, alpha-IIb-beta-3) and abolished human umbilical vein endothelial cell (HUVEC) spreading, but not attachment. to RGD mutant vWF (Beacham, D. A. Wise, R. J., Turci. S. M. and Handin, R. I. 1992. J. Biol. Chem. 167. 3409-3415). These results suggested that in addition to the vitronectin receptor (VNR, alpha-v-beta-3), a second endothelial membrane glycoprotein can mediate HUVEC adhesion to vWF. HUVEC attachment to wild-type (WT) and RGD-mutant vWF was reduced by two proteins known to block the vWF-platelet glycoprotein Ib/IX (GpIb/IX) interaction. the monoclonal antibody AS-7 and the recombinant polypeptide, vWF-A1. The addition of cytochalasin B or DNase I to disrupt potential GPIb-alpha-cytoskeletal interactions enhanced the immunoprecipitation of endothelial GPIb-alpha, caused HUVEC to round up. and increased HUVEC adhesion to RGD mutant vWF. These results indicate that while the VNR is the primary adhesion receptor for vWF, endothelial GPI-beta-alpha can mediate HUVEC attachment to vWF. GpIb-dependent attachment could contribute to HUVEC adhesion under conditions when cell surface expression of the VNR is downregulated, and VNR-dependent adhesion is reduced.