The platelet glycoprotein IIb/IIIa-like protein in human endothelial cells promotes adhesion but not initial attachment to extracellular matrix.
On platelets the membrane glycoprotein IIb/IIIa complex (GPIIb/IIIa) functions in adhesive interactions with fibrinogen, von Willebrand factor, and fibronectin. However, the function of GPIIb/IIIa-like proteins on endothelial cells, as well as the ligand(s) the complex binds, is unknown. Using a highly specific polyclonal antibody we have explored the function of GPIIb/IIIa-like proteins on human umbilical vein endothelial cells (HUVE). Analysis by immunoblotting shows that this antiserum recognizes the endothelial GPIIIa-like protein of the complex. The IgG fraction of the polyclonal antiserum and its Fab' fragments detach confluent and subconfluent HUVE from extracellular substrata. The effect of the anti-GPIIb/IIIa IgG is not toxic as the detached cells maintain their viability after trypsinization and replating. Anti-GPIIb/IIIa IgG does not inhibit HUVE binding to extracellular matrix or purified fibronectin in an attachment assay despite the presence of intact GPIIb/IIIa on HUVE detached from substrate by various methods. Apparently, the GPIIb/IIIa-like protein on HUVE is important in normal HUVE adhesion to the extracellular matrix, but it is not required in the initial attachment of HUVE to extracellular matrix.
Chen
C S
CS
Department of Medicine, University of Washington, Seattle 98195.
Thiagarajan
P
P
Schwartz
S M
SM
Harlan
J M
JM
Heimark
R L
RL
D002448:Cell Adhesion; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D006801:Humans; D007158:Immunologic Techniques; D007163:Immunosorbent Techniques; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D009842:Oligopeptides / Q000138:chemical synthesis / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism
D008565:Membrane Proteins; D009842:Oligopeptides; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface