title: Adhesive properties of the beta 3 integrins: comparison of GP IIb-IIIa and the vitronectin receptor individually expressed in human melanoma cells.
abstract: Glycoprotein IIb-IIIa (alpha IIb beta 3) and the vitronectin receptor (alpha v beta 3), two integrins that share the common beta 3 subunit, have been reported to function as promiscuous receptors for the RGD-containing adhesive proteins fibrinogen, vitronectin, fibronectin, von Willebrand factor, and thrombospondin. The present study was designed to establish a cell system for the expression of either GP IIb-IIIa or the vitronectin receptor in an otherwise identical cellular environment and to compare the adhesive properties of these two integrins with those of native GP IIb-IIIa and the vitronectin receptor constitutively expressed in HEL cells or platelets. M21 human melanoma cells lack GP IIb-IIIa and use the vitronectin receptor to attach to vitronectin, fibrinogen, fibronectin, and von Willebrand factor. To study the functional properties of GP IIb-IIIa in these cells, we transfected GP IIb into M21-L cells, a variant of M21 cells (Cheresh, D.A., and R.C. Spiro. 1987. J. Biol. Chem. 262:17703-17711), which lack the expression of functional alpha v and are therefore unable to attach to vitronectin, fibrinogen, and von Willebrand factor. Transfectants expressing GP IIb were isolated by immunomagnetic beads and surface expression of the GP IIb-IIIa complex was documented by FACS analysis and immunoprecipitation experiments performed with 125I-labeled M21-L/GP IIb cells. Comparative functional studies demonstrated that GP IIb-IIIa expressed in M21-L/GPIIb cells as well as native GP IIb-IIIa constitutively expressed in HEL-5J20 cells (an HEL variant lacking alpha v beta 3) mediated cell attachment to immobilized fibrinogen, but not to vitronectin or von Willebrand factor, whereas the vitronectin receptor expressed in M21 cells and HEL-AD1 cells (an HEL variant expressing alpha v beta 3) mediated cell attachment to fibrinogen, vitronectin, and von Willebrand factor. Similarly, PGl2-treated resting platelets attached to immobilized fibrinogen but not to vitronectin or von Willebrand factor, and this attachment could be inhibited by mAb A2A9 (directed against a functional site on the GP IIb-IIIa complex). However, in contrast to platelets, which adhered to vitronectin and von Willebrand factor after stimulation by thrombin or PMA, activation of the protein kinase C pathway in M21-L/GP IIb or HEL cells did not induce cell adhesion to vitronectin or von Willebrand factor.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: COR Therapeutics Inc., South San Francisco, California 94080.
authors.forename: N
authors.initials: N
authors.lastname: Kieffer
authors.forename: L A
authors.initials: LA
authors.lastname: Fitzgerald
authors.forename: D
authors.initials: D
authors.lastname: Wolf
authors.forename: D A
authors.initials: DA
authors.lastname: Cheresh
authors.forename: D R
authors.initials: DR
authors.lastname: Phillips
mesh_terms: D001792:Blood Platelets / Q000378:metabolism; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D005340:Fibrinogen / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006801:Humans; D039661:Integrin beta3; D016023:Integrins / Q000235:genetics / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D011233:Precipitin Tests; D011499:Protein Processing, Post-Translational; D011971:Receptors, Immunologic / Q000378:metabolism*; D019030:Receptors, Vitronectin; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D015815:Cell Adhesion Molecules; D039661:Integrin beta3; D016023:Integrins; D010980:Platelet Membrane Glycoproteins; D011971:Receptors, Immunologic; D019030:Receptors, Vitronectin; D005340:Fibrinogen