title: Involvement of alpha v beta 3 integrin in mediating fibrin gel retraction.
abstract: Platelet integrin alpha IIb beta 3 (GPIIb-IIIa) plays important roles in platelet-mediated clot retraction. However, little is known about the mechanisms of clot retraction mediated by nucleated cells. In this report, we demonstrate that another member of the beta 3 integrin family, alpha v beta 3, is involved in clot retraction mediated by nucleated cells. Retraction of fibrin clots was observed using a human melanoma cell line, C32TG, which contains no alpha IIb beta 3 complex. This retraction was inhibited by RGD-containing peptide, monoclonal anti-beta 3, and anti-alpha v beta 3 antibodies. Immunoelectron microscopic studies revealed a direct interaction between beta 3 integrin and fibrin fibers at an early stage of clot retraction. We found that another human embryonal cell line, 293, which is known to express alpha v beta 1, but no alpha v beta 3, lacks fibrin gel retractile activity. Upon transfection of beta 3 DNA into 293 cells, the beta 3 subunit formed a complex with an endogenous alpha v subunit. The beta 3-bearing transfectants were found to retract fibrin gels, which was specifically inhibited by anti-beta 3 antibody. In addition, a point mutation at Asp119 in the beta 3 ligand binding domain abolished the clot retractile activity of 293 transfectants, indicating the requirement of alpha v beta 3 ligand-binding activity. Our findings suggest that alpha v beta 3 is involved in mediating the interaction between the three-dimensional fibrin network and nucleated cells and in promoting "post-receptor occupancy" events.
authors.affiliation: Department of Cardiovascular Research, Tokyo Metropolitan Institute of Medical Science, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Katagiri
authors.forename: T
authors.initials: T
authors.lastname: Hiroyama
authors.forename: N
authors.initials: N
authors.lastname: Akamatsu
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Yamazaki
authors.forename: K
authors.initials: K
authors.lastname: Tanoue
mesh_terms: D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D003018:Clot Retraction; D004622:Embryo, Mammalian; D005337:Fibrin / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D016023:Integrins / Q000502:physiology*; D008545:Melanoma; D008854:Microscopy, Electron; D009842:Oligopeptides / Q000494:pharmacology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors; D016024:Receptors, Cytoadhesin / Q000502:physiology*; D019030:Receptors, Vitronectin; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D016023:Integrins; D009842:Oligopeptides; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D010980:Platelet Membrane Glycoproteins; D016024:Receptors, Cytoadhesin; D019030:Receptors, Vitronectin; D011994:Recombinant Proteins; C078174:Ro 43-5054; D005337:Fibrin; C058161:glycyl-arginyl-glycyl-aspartyl-seryl-proline; C058347:glycyl-arginyl-glycyl-glutamyl-seryl-proline