Local function of urokinase receptor at the adhesion contact sites of a metastatic tumor cell.
The local activity of urokinase and its receptor associated with a cloned cell (C5) obtained from the cloning of Detroit 562 was investigated. The cellular binding sites, similar structure to adhesion plaques, were visualized by fluorescein labeled urokinase and the number was determined to be 300 per cell. The binding sites for radioiodinated urokinase were found to be 30 thousand per cell. Thus, about as many as 100 receptor molecules per site was estimated to be associated with the cellular membrane domains. Immunofluorescence studies demonstrated that the receptors were colocalized with a set of adhesion and cytoskeletal proteins such as vinculin, alpha-actinin and actin; localizing at the adhesion sites. These proteins soluble in 9 M urea were able to be reconstituted by dialyzing out the urea against low ionic buffer solution. It was demonstrated that vinculin and actin were co-associated. Since cell bound urokinase revealed fibrinolytic activity, it was suggested that the focal adhesions of the migrating cells would facilitate proteolytic action when cells move across the matrix architectures.
Takahashi
K
K
Department of Physiology, Shimane Medical University, Izumo, Japan.
Ikeo
K
K
Gojobori
T
T
Tanifuji
M
M
D000185:Actinin / Q000032:analysis; D000199:Actins / Q000032:analysis; D002448:Cell Adhesion / Q000502:physiology; D002999:Clone Cells; D003598:Cytoskeletal Proteins / Q000032:analysis; D005455:Fluorescent Antibody Technique; D006801:Humans; D009362:Neoplasm Metastasis / Q000503:physiopathology*; D011956:Receptors, Cell Surface / Q000032:analysis / Q000502:physiology*; D055293:Receptors, Urokinase Plasminogen Activator; D014407:Tumor Cells, Cultured; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*; D016596:Vinculin
D000199:Actins; D003598:Cytoskeletal Proteins; C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D000185:Actinin; D016596:Vinculin; D014568:Urokinase-Type Plasminogen Activator