Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Through in situ hybridization of a cDNA probe to metaphase chromosomes, we localized the gene for the human urokinase receptor (PLAUR) on chromosome 19. RBG-banding permitted subchromosomal localization of the PLAUR gene to 19q13.
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PMID:Assignment of the human urokinase receptor gene (PLAUR) to 19q13. 132 36

New technology allows highly sensitive flow cytometric detection and quantitative analysis of intracellular antigens in normal and malignant hemopoietic cells. With this technology, the earliest stages of myeloid and lymphoid differentiation can easily and reliably be identified using antibodies directed against (pro-)myeloperoxidase/MPO, CD22 and CD3 antigens, respectively. Particularly for the analysis of undifferentiated acute myeloblastic leukemia (AML) cells, the immunological demonstration of intracellular MPO or its enzymatically inactive proforms is highly relevant, since other myeloid marker molecules such as CD33, CD13, or CDw65 are either not restricted to the granulomonocytic lineage or appear later in differentiation. By combining MPO staining with staining for lactoferrin (LF), undifferentiated cells can be distinguished from the granulomonocytic maturation compartment in bone marrow, since LF is selectively expressed from the myelocyte stage of differentiation onward. The list of informative intracellular antigens to be used in leukemia cell analysis will certainly expand in the near future. One candidate, intracellular CD68, has already been tested by us, and results are presented. Also dealt within this article are surface marker molecules not (as yet) widely used in leukemia cell analysis but with the potential to provide important additional information. Among them are the surface structures CD15, CD15s, CDw65, CD79a (MB-1), CD79b (B29), CD87 (uPA-R), and CD117 (c-kit).
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PMID:Flow cytometric analysis of cell-surface and intracellular antigens in leukemia diagnosis. 753 75

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.
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PMID:Urokinase plasminogen activator receptor, beta 2-integrins, and Src-kinases within a single receptor complex of human monocytes. 753 37

The receptor for urokinase plasminogen activator (uPA-R, CD87) is a glycosylphosphatidylinositol (GPI)-anchored 50 to 65 kD glycoprotein that, by regulating membrane-associated plasmin activity, may facilitate the invasion of inflammatory and malignant cells. Certain other GPI-anchored glycoproteins are shed from the cell membrane and exist as soluble products in vitro and in vivo. To determine if uPA-R undergoes a similar phenomenon, we have developed a sensitive enzyme-linked immunoabsorbent assay (ELISA) (using a rabbit antiserum as both capture and detection reagents) to measure the quantity of soluble uPA-R (suPA-R) in tissue culture supernatants and biologic fluids. Using this ELISA, we have detected suPA-R in the culture supernatants of U-937 cells and human monocytes stimulated in vitro by certain soluble inflammatory mediators (Sitrin et al, Blood 84:1268, 1994; Mizukami et al., Clin Res 42:115A, 1994). To determine if suPA-R exists in vivo, we have screened the plasma of 20 normal volunteers (mean +/- SD, 3 +/- 3 ng/mL; median, 2 ng/mL; range, 1 to 11 ng/mL [serum values slightly higher]); the plasma of 13 ICU patients with clinical sepsis syndrome (mean +/- SD, 30 +/- 11 ng/mL; median, 11 ng/mL; range, 4 to 221 ng/mL); and the extravascular fluids (pleural, pericardial, and peritoneal) of 84 individuals with presumed inflammatory or malignant conditions (mean +/- SD, 21 +/- 39 ng/mL; median, 10 ng/mL; range, 2 to 253 ng/mL). Among the latter specimens, most were inflammatory exudates (only six were malignant by positive cytology) with the highest quantities of suPA-R associated with neutrophilic exudates. The solubility of suPA-R contained within these fluids was confirmed by reanalysis after ultracentrifugation to remove particulate material. When tested in a uPA ligand capture ELISA, representative specimens of extravascular body fluids and sepsis plasma contained suPA-R capable of binding uPA ligand (generally representing a small fraction of the immunoreactive material). We conclude from these data that suPA-R is immunologically detectable in vitro and in vivo with high concentrations of receptor found under conditions of inflammatory stimulation. The possibility of suPA-R's biologic activity is suggested by its partial retention of ligand binding capacity.
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PMID:Enzyme-linked immunoabsorbent assay detection of a soluble form of urokinase plasminogen activator receptor in vivo. 779 25

Extravasation and intravasation of tumor cells in solid malignant tumors is controlled by 3 steps: 1) attachment to and interaction of tumor cells with components of the basement membrane and the extracellular matrix, 2) local proteolysis, and 3) tumor cell migration. Evidence has accumulated that different types of tumor-associated proteases, their inhibitors and receptors are involved in tumor invasion and metastasis. Four different classes of proteases are known to be correlated with the malignant phenotype: 1) Matrix metalloproteases; including collagenases, gelatinases and stromelysins. 2) Cysteine proteases; including cathepsins B and L. 3) Aspartyl protease cathepsin D. 4) Serine proteases; including plasmin and tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). A strong independent prognostic value (relapse-free and/or overall survival) has especially been demonstrated for uPA and its inhibitor PAI-1 in patients with cancer of the breast, ovary, stomach, esophagus, colon, lung, and kidney thus predicting the course of the cancer disease. The strong correlation between elevated uPA and/or PAI-1 values in primary cancer tissues and the malignant phenotype of cancer cells has prompted to explore new tumor biology-oriented concepts in order to suppress uPA or uPA receptor (CD87) expression or to abrogate interaction of uPA with CD87. Various very different approaches to interfere with the expression or reactivity of uPA or CD87 at the gene or protein level were successfully tested including antisense oligonucleotides, antibodies, inhibitors and recombinant or synthetic uPA and CD87 analogues.
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PMID:Urokinase-type plasminogen activator (uPA) and its receptor (CD87): a new target in tumor invasion and metastasis. 855 77

The expression of plasminogen activators and inhibitors was examined in denuded arteries. Within 5 days, smooth muscle cells (SMCs) on the luminal surface expressed the mRNA for tissue-type plasminogen activator (TPA), urokinase type plasminogen (UPA), the receptor for UPA (UPAR), and plasminogen activator inhibitor type-1 (PAI-1). Similar results were seen after 8 days. Six weeks later, only TPA mRNA was still expressed by SMCs on the luminal surface. En face casein zymograms revealed a net fibrinolytic activity in areas covered with luminal SMCs. Reverse zymography showed no antifibrinolytic activity in these zones. Quiescent endothelial cells did not express TPA, UPA, UPAR, or PAI-1 mRNA. Regenerating endothelium at the wound edge strongly expressed TPA. UPA, and UPAR, as well as PAI-1. UPA and UPAR expression was highly restricted to cells at the wound edge and was not present elsewhere. En face zymography showed no plasmin activity in endothelialized areas, and reverse zymography showed a net fibrinolytic activity in endothelialized zones. These results suggest that plasminogen activator and inhibitor expression correlates with the migration of both SMCs and endothelial cells into an arterial wound.
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PMID:Migration of arterial wall cells. Expression of plasminogen activators and inhibitors in injured rat arteries. 859 99

Urokinase receptors (uPAR; CD87) from complexes with complement receptor 3 (CR3) (CD11b/CD18), a beta2 integrin. In this study, we sought to determine if this association modulates the adhesive function of CR3. Both CR3 and uPAR concentrate at the ventral surface of fibrinogen-adherent human monocytes, and CR3-uPAR coupling increases substantially upon adhesion to fibrinogen. Pretreatment with anti-uPAR monoclonal antibody reduced adhesion to CR3 counterligands (fibrinogen and keyhole limpet hemocyanin) by 50%, but did not affect adhesion to fibronectin, a beta1 integrin counterligand. Antisense (AS) oligonucleotides were used to determine if selectively suppressing uPAR expression also modulates CR3 adhesive function. AS-uPAR oligo reduced CR3-dependent adhesion by 43+/-9% (P<0.01), but did not affect CR3-independent adhesion. To determine if the effects of uPAR are mediated through its ligand, monocytes were pre-treated with AS oligo to block uPA expression. Unlike the effects of blocking uPAR expression, AS-uPA oligo increased adhesion by 46% (P<0.005), and exogenous intact uPA, but not uPA fragments, reversed this effect. We conclude that complex formation with uPAR facilitates the adhesive functions of CR3. This function of uPAR is not dependent upon its occupancy with uPA, which negatively influences adhesion.
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PMID:The urokinase receptor (CD87) facilitates CD11b/CD18-mediated adhesion of human monocytes. 862 79

The amino-terminal fragment of human uPA (ATF; amino acids 1-135), which contains the binding site for the uPA receptor (uPAR, CD87) was expressed in the yeast Saccharomyces cerevisiae. Recombinant yeast ATF, modified and extended by an amino-terminal in-frame insertion of a His6 tract, was purified from total protein extracts by nickel chelate affinity chromatography and shown to be functionally active since it efficiently competes with uPA for binding to cell-surface-associated uPAR. The ATF expression plasmid served as a template for the construction of a series of site-directed mutants in order to define those amino acids that are important for binding to uPAR. All mutant ATF proteins but one (deletion of Ser26) were expressed in a stable form (about 20-30 ng/mg total protein) and the binding capacity of each mutant was tested by a uPA-ligand binding assay employing recombinant uPAR immobilized to a microtiter plate. Each of the 11 amino acids of loop B of the binding region of uPA (amino acids 20-30) were individually substituted with alanine. Lys23, Tyr24, Phe25, IIe28, and Trp30 were important determinants for uPAR binding. A systematic alanine scan was also performed with chemically synthesized linear peptides spanning amino acids 14-32 of ATF. Comparable results to those with the yeast ATF mutants were obtained. In a different set of experiments, those amino acids of the uPAR-binding region of uPA that are only conserved between man and baboon but not in other species were altered: whereas substitution of Thr18 by alanine or Asn32 by serine had hardly any effect, replacement of Asn22 by tyrosine and Trp30 by arginine (both positions are strictly conserved in other mammals) led to ATF variants incapable of interacting with human uPAR. Deletion of either Val20, Ser21, Lys23, His29 or Val20 plus Ser21, respectively, also generated non-reactive ATF mutants. Finally, Lys23 in ATF was substituted with certain amino acids: whereas the replacement of Lys23 by alanine, histidine or glutamine generated ATF variants with moderate uPAR-binding activity, the introduction of a negatively charged amino acid (exchange of Lys23 by glutamic acid) completely abolished uPAR-binding activity. The results presented for the ATF mutants and uPA-derived peptides may provide clues necessary to establish the nature of the physical interaction of uPA with its receptor and may help to develop uPA-derived peptide analogues as potential therapeutic agents to block tumor cell-associated uPA/uPAR interaction.
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PMID:Systematic mutational analysis of the receptor-binding region of the human urokinase-type plasminogen activator. 864 21

The leukocyte integrin Mac-1 (CD11b/CD18) and the urokinase receptor (uPAR, CD87) mediate complementary functions in myelomonocytic cells. Both receptors promote degradation of fibrin(ogen) and also confer adhesive properties on cells because Mac-1 and uPAR bind fibrin and vitronectin, respectively. Staining of lung biopsy specimens from patients with acute lung injury indicated that fibrin and vitronectin colocalize at exudative sites in which macrophages bearing these receptors accumulate. Because of the parallel roles and physical proximity of Mac-1 and uPAR, the capacity of these receptors to functionally interact was explored. Induction of Mac-1 and uPAR expression on monocytic cell lines by transforming growth factor- beta 1 and 1.25-(OH)2 vitamin D3 conferred urokinase and uPAR-dependent adhesion to vitronectin, which was further promoted by engagement of Mac-1. Vitronectin attachment promoted subsequent Mac-1-mediated fibrinogen degradation threefold to fourfold. In contrast, enhancement of uPAR occupancy by exogenous urokinase or receptor binding fragments thereof inhibited Mac-1 function. Addition of urokinase progressively inhibited Mac-1-mediated fibrinogen binding and degradation (maximal inhibition, 91% +/- 14% and 72% +/- 15%, respectively). Saturation of uPAR with urokinase also inhibited binding of the procoagulant Mac-1 ligand, Factor X. These inhibitory effects of uPAR were reproduced in fresh monocytes, cultured monocytic cells, and in Chinese hamster ovary (CHO) cells transfected with both human Mac-1 and human uPAR. These data show that the procoagulant and fibrinolytic potential of monocytic cells is co-ordinately regulated by ligand binding to both Mac-1 and uPAR and identify uPAR as a regulator of integrin function. Vitronectin-enhanced fibrin(ogen) turnover by Mac-1 may operate as a salvage pathway in the setting of urokinase and plasmin inhibitors to promote clearance of the provisional matrix and subsequent healing.
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PMID:Mac-1 (CD11b/CD18) and the urokinase receptor (CD87) form a functional unit on monocytic cells. 887 19

Keratinocytes synthesize and secrete urokinase-type plasminogen activator (uPA), which is bound in an autocrine manner to a specific receptor (uPA-R, CD87) at their surface. Plasminogen, which is also bound to membrane binding sites, is readily activated by uPA-R-bound uPA. Thus, plasmin for proteolysis of pericullular glycoproteins is provided. While uPA-R and uPA are at low to undetectable levels in keratinocytes of the normal epidermis, both compounds are upregulated in migrating keratinocytes during reepithelialization of epidermal defects and in affected keratinocytes of various epidermal disorders, including bullous dermatoses. We have hypothesized that the disturbance of cell/matrix interactions--a common feature of these diverse pathological situations--induces uPA/uPA-R. Accordingly, we explored whether the dispase-mediated detachment of cultured keratinocytes, which have formed a multilayered epidermis-like structure in vitro, induced uPA and uPA-R. We found increases in uPA secretion, cell-associated uPA activity, and uPA- and uPA-R-antigen in keratinocytes upon dispase-mediated detachment from their growth substratum. The increase was preceded by an increase in uPA-R- and uPA-specific mRNA, which was not observed when the proteinase inhibitor phosphoramidon was added together with dispase. In conclusion, we present evidence that experimental detachment with dispase provides signals for the concomitant upregulation of uPA-R and uPA. The findings support the hypothesis that cell/matrix interactions may influence the expression of the cell surface-associated PA system in human keratinocytes.
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PMID:Dispase-mediated basal detachment of cultured keratinocytes induces urokinase-type plasminogen activator (uPA) and its receptor (uPA-R, CD87). 891 17


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