Urokinase plasminogen activator receptor, beta 2-integrins, and Src-kinases within a single receptor complex of human monocytes.
The glycosylphosphatidylinositol (GPI)-anchored membrane protein urokinase plasminogen activator-receptor (uPA-R; CD87) is one of the key molecules involved in migration of leukocytes and tumor cells. uPA bound to uPA-R provides the cell proteolytic potential used for degradation of extracellular matrix. uPA-R is also involved in induction of cell adhesion and chemotaxis. Here, we provide a molecular explanation for these uPA-R-related cellular events. By size fractionation of monocyte lysate and affinity isolation on its natural ligand uPA, we demonstrate uPA-R as a component of a receptor complex of relatively large size. Reprecipitation and immunoblotting techniques allowed us to detect the protein tyrosine kinases (PTKs) p60fyn, p53/56lyn, p58/64hck, and p59fgr as components of this "uPA-R complex". Activation of monocytes even with enzymatically inactivated uPA resulted in induction of tyrosine phosphorylation, suggesting modulation of uPA-R-associated PTKs upon ligand binding. In spite of their presence in large complexes, we did not find the GPI-linked proteins CD14, CD58, and CD59 in the uPA-R complex, which indicates the presence of different receptor domains containing GPI-linked proteins in monocytes. However, we identified the leukocyte integrins LFA-1 and CR3 as components of the uPA-R complex as indicated by coisolation of these molecules, as well as by cocapping and comodulation of uPA-R and leukocyte integrins on the monocyte surface. The assemblage of uPA-R, PTKs and membrane spanning beta 2-integrins in one receptor complex indicates functional cooperation. In regard to the involvement of these molecules in pericellular proteolysis, signal transduction, as well as adhesion and chemotactic movement, we suggest uPA-R complex as a potential cellular device for cell migration.
Bohuslav
J
J
Institute of Immunology, Vienna International Research Cooperation Center, SFI University of Vienna, Austria.
Horejsí
V
V
Hansmann
C
C
Stöckl
J
J
Weidle
U H
UH
Majdic
O
O
Bartke
I
I
Knapp
W
W
Stockinger
H
H
D015703:Antigens, CD / Q000032:analysis; D018821:CD18 Antigens; D002448:Cell Adhesion; D002465:Cell Movement; D006801:Humans; D016023:Integrins / Q000032:analysis*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000032:analysis; D046911:Macromolecular Substances; D016177:Macrophage-1 Antigen / Q000032:analysis; D009000:Monocytes / Q000737:chemistry*; D009097:Multienzyme Complexes / Q000032:analysis*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000032:analysis; D011518:Proto-Oncogene Proteins / Q000032:analysis; D051076:Proto-Oncogene Proteins c-fyn; D051572:Proto-Oncogene Proteins c-hck; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis*; D011956:Receptors, Cell Surface / Q000032:analysis*; D055293:Receptors, Urokinase Plasminogen Activator; D015398:Signal Transduction; D019061:src-Family Kinases
D015703:Antigens, CD; D018821:CD18 Antigens; D016023:Integrins; D016169:Lymphocyte Function-Associated Antigen-1; D046911:Macromolecular Substances; D016177:Macrophage-1 Antigen; D009097:Multienzyme Complexes; C524898:PLAUR protein, human; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; C494957:FYN protein, human; C496631:HCK protein, human; D051076:Proto-Oncogene Proteins c-fyn; D051572:Proto-Oncogene Proteins c-hck; C060902:lyn protein-tyrosine kinase; C053102:proto-oncogene proteins c-fgr; D019061:src-Family Kinases