Regulation of urokinase by cellular receptors and inhibitors

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5614345

Hebert, C A

Several cell types display binding sites for {sup 125}I-urokinase which in certain cases are occupied with endogenous urokinase. These sites appear to focus urokinase at cell surfaces and hence may participate in tissue matrix destruction and cell invasion. Using immunofluorescence double labeling, the author shows that the receptor-bound urokinase present on human foreskin fibroblasts and HT1080 human fibrosarcoma cells is colocalized with vinculin, an intracellular actin-binding protein that is deposited at cell to substratum focal adhesion sites. Thus, this indicates linkage of the plasminogen/plasmin system both to sites of cell adhesion and to the cytoskeleton. He furthermore reports that neither EGF, TGF{beta} or PDGF significantly altered the shape or intensity of the receptor-bound urokinase clusters but that thrombin, at mitogenic doses, caused a disappearance of the urokinase strands and a loss or gross alteration of the underlying focal adhesion plaques, as indicated by immunofluorescence staining for vinculin and talin, and by interference reflection microscopy. These observations suggest that thrombin may be a unique effector of cell adhesion, shape and movement. He used a quantitative in vitro invasion assay to study the role of plasminogen activator inhibitors type 1 and 2 (PAI-1, PAI-2) and protease nexin (PN1) in basement membrane (BM) invasion by {sup 125}I-iododeoxyuridine-labeled HT 1080 cells. The results obtained showed that 5 {mu}g/ml of PAI-1, PAI-2 and PN1 preadsorbed to the BM completely blocked HT1080 invasion. On the contrary an anti-PAI-1 monoclonal antibody induced an approximately two-fold increase in invasion. {sup 125}I-fibrinogen was polymerized on the amnion BM and the fibrinolytic activity of the cells was measured under the invasion assay conditions by measuring the radioactivity in the culture medium at different time points.

• Research Organization: Kansas Univ., Lawrence, KS (USA)
• OSTI ID: 5614345
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CELL CONSTITUENTS
CELL MEMBRANES
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DOUBLE LABELLING
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ENZYME INHIBITORS
ENZYMES
FIBRINOLYTIC AGENTS
FIBROBLASTS
GROWTH FACTORS
HEMATOLOGIC AGENTS
HYDROLASES
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLING
MAMMALS
MAN
MEMBRANE PROTEINS
MEMBRANES
MITOGENS
NONSPECIFIC PEPTIDASES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
SOMATIC CELLS
TRACER TECHNIQUES
TUMOR CELLS
UROKINASE
VERTEBRATES