A 130-kDa protein on endothelial cells binds to amino acids 15-42 of the B beta chain of fibrinogen.
Factors which stimulate the release of von Willebrand factor (vWf) from endothelial cell Weibel-Palade bodies and which induce the expression of the leukocyte-binding adhesion molecule P-selectin (PADGEM, GMP-140, CD62) on the endothelial cell surface remain incompletely characterized. Fibrin but not fibrinogen is a potent stimulus for the release of stored von Willebrand factor from endothelial cells. Removal of fibrinopeptides A and B from fibrinogen occurs during the formation of fibrin, and the removal of fibrinopeptide B is a requirement for fibrin to induce vWf secretion. The cleavage of fibrinopeptide A by reptilase enzyme forms a fibrin gel yet it is incapable of stimulating Weibel-Palade body degranulation. As a consequence of removing fibrinopeptide B, B beta 15-42 becomes the new NH2 terminus of the beta chain of fibrin. We have shown that the peptide B beta 15-42 in solution inhibits the release of vWf stimulated by fibrin. In addition, B beta 15-42 coupled to ovalbumin supports the binding and spreading of endothelial cells, while a scrambled form of this peptide coupled to the same carrier does not. We investigated whether these determinants near the amino terminus of the beta chain of fibrin bind to a specific protein on the surface of endothelial cells. A 130-kDa protein was isolated from surface-labeled human umbilical vein endothelial cells by specific binding to B beta 15-42 immobilized on Sepharose. This glycoprotein was eluted with the B beta 15-42 peptide in solution but not with the scrambled form of this peptide. The fibrin-derived peptides B beta 19-26 and B beta 37-56-cysteine were also incapable of eluting the 130-kDa protein bound to immobilized B beta 15-42 as were the arginine-glycine-aspartic acid-serine RGDS tetrapeptide and EDTA. The 130-kDa protein is recognized neither by antibodies to the known integrins found on endothelial cells nor by antibodies to CD31 (endoCAM, PECAM-1), a member of the immunoglobulin family of receptors found on endothelial cells. The beta chain of fibrin thus contains a sequence near its amino terminus which specifically binds to what is likely a novel endothelial cell surface protein. This glycoprotein may promote endothelial cell adhesion to fibrin during the wound healing process and is a candidate for a receptor involved in fibrin-mediated release of Weibel-Palade bodies from endothelial cells.
Center for Hemostasis and Thrombosis Research, New England Medical Center, Boston, Massachusetts 02111.
J K
JK
Erban
D D
DD
Wagner
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism*; D001345:Autoradiography; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000378:metabolism*; D005338:Fibrin Fibrinogen Degradation Products; D005345:Fibrinopeptide B / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010047:Ovalbumin / Q000378:metabolism; D019007:P-Selectin; D010446:Peptide Fragments / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011233:Precipitin Tests; D014357:Trypsin / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
D000596:Amino Acids; D015815:Cell Adhesion Molecules; D005338:Fibrin Fibrinogen Degradation Products; D008565:Membrane Proteins; D019007:P-Selectin; D010446:Peptide Fragments; D010980:Platelet Membrane Glycoproteins; C033786:fibrinogen Bbeta (15-42); D014841:von Willebrand Factor; D005345:Fibrinopeptide B; D010047:Ovalbumin; D014357:Trypsin