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Chavakis, T.* ; Kanse, S.M.* ; Yutzy, B.* ; Lijnen, H.R.* ; Preissner, K.T.*

Vitronectin concentrates proteolytic activity on the cell surface and extracellular matrix by trapping soluble urokinase receptor-urokinase complexes.

Blood 91, 2305-2312 (1998)
DOI PMC
Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
Urokinase-type-plasminogen activator (uPA) and its receptor are localized in the vessel wall where they are involved in cellular activation and remodelling processes. Besides the cell surface glycolipid (GPI)-anchored urokinase receptor (uPAR), which binds uPA with high affinity, recent evidence points to the existence of soluble uPAR (suPAR), as well. In the present study, the origin, binding mechanism, and cellular effects of suPAR were examined. Under basal conditions human vascular smooth muscle cells (HVSMC), human umbilical vein endothelial cells (HUVEC), and monocytic cells released 0.1 to 2 ng/mL suPAR, which was increased twofold to fivefold after phorbol ester (PMA) stimulation, as measured by a function-dependent enzyme-linked immunosorbent assay (ELISA). suPAR alone did not bind to HVSMC or HUVEC, but reduced cellular uPA binding by 50% to 70%. However, after removal of GPI-uPAR with phosphatidylinositol-specific phospholipase C, suPAR dose-dependently increased uPA binding by fourfold to fivefold. This increase in binding was completely inhibited by vitronectin (VN) and by a monoclonal antibody against VN, but not by other matrix proteins or antibodies. Thus, VN-mediated uPA binding to cells was regulated by the ratio of soluble to surface-associated uPAR. In a uPAR-deficient cell line (LM-TK-), suPAR increased uPA binding up to 10-fold, whereas the truncated receptor lacking the amino-terminal uPA-binding domain was ineffective. The formation of a ternary uPA/suPAR/VN-complex on the cell surface and the free extracellular matrix could be inhibited by a monoclonal antibody against VN, as well as by plasminogen activator inhibitor-1 (PAI-1). Moreover, VN-mediated binding of the uPA/suPAR-complex led to a fivefold increase in plasminogen activator activity. Through this novel pathway, VN concentrates the uPA/suPAR-complex to cell surfaces and extracellular matrix sites, leading to the accumulation of plasminogen activator activity required for cell migration and tissue remodelling processes.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Sprache englisch
Veröffentlichungsjahr 1998
HGF-Berichtsjahr 0
ISSN (print) / ISBN 0006-4971
e-ISSN 1528-0020
Zeitschrift Blood
Quellenangaben Band: 91, Heft: 7, Seiten: 2305-2312 Artikelnummer: , Supplement: ,
Verlag American Society of Hematology
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Pancreatic Islet Research (IPI)
PubMed ID 9516128
Erfassungsdatum 1998-12-31