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)

We recently identified DPC4/Smad4 as a candidate tumor suppressor gene mutated or lost in one half of pancreatic carcinomas and in a subset of colon and biliary tract carcinomas. DPC4 plays a key role in signal transduction of the TGF-beta superfamily of molecules and inactivation of TGF-beta mediated growth inhibition is supposed to be the driving force for DPC4 inactivation in human tumors. However, DPC4 mediated tumor suppression by reconstitution of defective cells has not yet been reported. Here we show suppression of tumorigenicity in nude mice by stable reexpression of DPC4 in SW480 colon carcinoma cells. In vitro growth of DPC4-transfected cells was not affected and resistance towards TGF-beta mediated growth inhibition was retained. Instead, cells exhibited morphological alterations and adhesion and spreading were accelerated. These phenotypic changes were associated with reduced expression levels of the endogenous urokinase-type plasminogen activator (uPA) and plasminogen-activator-inhibitor-1 (PAI-1) genes, the products of which are implicated in the control of cell adhesion and invasion. In patients, high expression levels of uPA and PAI-1 correlate with poor prognosis. Thus, reduced expression of uPA and PAI-1 is consistent with suppression of tumorigenicity in DPC4 reconstituted cells. These results demonstrate DPC4's tumor suppressive function and suggest a potential role for DPC4 as a modulator of cell adhesion and invasion.
 ...
PMID:DPC4/SMAD4 mediated tumor suppression of colon carcinoma cells is associated with reduced urokinase expression. 1034 Mar 87

Vascular endothelial cells possess antithrombotic properties, which are determined by the balance between plasminogen activators (PAs) and PA inhibitors (PAls). A cell line, TKM-33, has been established and cloned from human umbilical vein endothelial cells, was previously reported to produce a large amount of urokinase-type PA (u-PA) and small amounts of tissue-type plasminogen activator (t-PA) and PA inhibitor-1 (PAI-1). Moreover, TKM-33 expressed the u-PA receptor (u-PAR) which plays an important role in the localization of fibrinolytic activity on cell surface. In the present study, we investigated the localization of u-PA, t-PA, PAI-1 and u-PAR in TKM-33 by using immunofluorescence staining technique. The endothelial cells were strongly stained with anti-PAI-1, anti-u-PA and anti-u-PAR IgGs, and slightly with anti-t-PA IgG. The double immunofluorescence staining with mouse anti-u-PA IgG and rabbit anti-u-PAR IgG followed by rhodamine-conjugated anti-mouse IgG and FITC-conjugated anti-rabbit IgG showed the co-localization of u-PA and u-PAR on the same section of endothelial cells. Although u-PA antigen also existed in the cytoplasm of endothelial cells, u-PAR antigen did not. The treatment of endothelial cells with phorbol-myristate-acetate (PMA) upregulated the expression of u-PA and u-PAR antigens. In this stimulation, u-PAR antigen was detected not only on the surface of the cells but also in the cytoplasm. Thus, the binding of u-PA to u-PAR was confirmed by double immunofluorescence staining.
 ...
PMID:Co-localization of urokinase and its receptor on established human umbilical vein endothelial cell. 1036 70

Vitronectin is a multifunctional glycoprotein present in blood and in the extracellular matrix. It binds glycosaminoglycans, collagen, plasminogen and the urokinase-receptor, and also stabilizes the inhibitory conformation of plasminogen activation inhibitor-1. By its localization in the extracellular matrix and its binding to plasminogen activation inhibitor-1, vitronectin can potentially regulate the proteolytic degradation of this matrix. In addition, vitronectin binds to complement, to heparin and to thrombin-antithrombin III complexes, implicating its participation in the immune response and in the regulation of clot formation. The biological functions of vitronectin can be modulated by proteolytic enzymes, and by exo- and ecto-protein kinases present in blood. Vitronectin contains an RGD sequence, through which it binds to the integrin receptor alpha v beta 3, and is involved in the cell attachment, spreading and migration. Antibodies against alpha v beta 3 or synthetic peptides containing an RGD sequence are now being tested as therapeutic agents in the treatment of human cancers, bone diseases (e.g. osteoporosis) and in pathological disorders which involve angiogenesis.
 ...
PMID:Vitronectin. 1039 14

The plasminogen activator/plasmin system is known to initiate a proteolytic cascade resulting in the activation of matrix metalloproteinases in vitro leading to the degradation of extracellular matrix. To investigate whether or not this cascade is present during delayed wound healing and contributes to the pathophysiological basis of impaired healing we examined the temporal expression of urokinase plasminogen activator, plasminogen activator inhibitor-1 and gelatinase-B in fluid collected from chronic venous leg ulcers compared to acute surgical mastectomy wounds. Using a chromogenic substrate assay, levels of active urokinase plasminogen activator in chronic wounds were found to be about five fold higher compared to sera and two fold higher compared to mastectomy wounds. Levels of active plasminogen activator inhibitor-1 in chronic wounds were four times higher than those found in sera and two times higher than those found in mastectomy wound fluid. Using a fibrin overlay system and reverse zymography, we found that when the wound was not healing, the expression of urokinase plasminogen activator in chronic wound fluid was initially detected in the active forms (50 and 33 kDa), but that as the wound healed and decreased in size, was detected as an inhibitor- bound urokinase plasminogen activator-plasminogen activator inhibitor-1 complex ( congruent with 80-116 kDa). When the expression of active urokinase plasminogen activator was highest, no plasminogen activator inhibitor-1 was detectable. In contrast, urokinase plasminogen activator was always detected in the inhibitor bound form as a urokinase plasminogen activator-plasminogen activator inhibitor-1 complex in blood- and plasma-derived serum and mastectomy wound fluid. Plasminogen activator inhibitor-1 was detected in blood-derived serum and mastectomy wound fluid but not in plasma derived serum. Expression of matrix metalloproteinase-9 in chronic wound fluids, analyzed by gelatin zymography, showed that when urokinase plasminogen activator was detected in the active forms, matrix metalloproteinase-9 was overexpressed by approximately twice that found in mastectomy wounds and approximately 30 times that detected in blood-derived sera. When urokinase plasminogen activator appeared almost entirely as an enzyme- inhibitor complex, the level of expression of matrix metalloproteinase-9 was similar to that seen in mastectomy wound fluid. We conclude that the switch in urokinase plasminogen activator expression from an active to inhibitor bound form correlates with the decrease seen in matrix metalloproteinase-9 expression suggesting the presence of a proteolytic cascade initiated by the plasminogen activator/plasmin system during wound healing leading to the activation of matrix metalloproteinase-9. In addition, expression of urokinase plasminogen activator and matrix metalloproteinase-9 appear to be useful biomarkers to determine clinical wound healing status.
 ...
PMID:Temporal expression of urokinase plasminogen activator, plasminogen activator inhibitor and gelatinase-B in chronic wound fluid switches from a chronic to acute wound profile with progression to healing. 1041 51

Cardiac rupture is a fatal complication of acute myocardial infarction lacking treatment. Here, acute myocardial infarction resulted in rupture in wild-type mice and in mice lacking tissue-type plasminogen activator, urokinase receptor, matrix metalloproteinase stromelysin-1 or metalloelastase. Instead, deficiency of urokinase-type plasminogen activator (u-PA-/-) completely protected against rupture, whereas lack of gelatinase-B partially protected against rupture. However, u-PA-/- mice showed impaired scar formation and infarct revascularization, even after treatment with vascular endothelial growth factor, and died of cardiac failure due to depressed contractility, arrhythmias and ischemia. Temporary administration of PA inhibitor-1 or the matrix metalloproteinase-inhibitor TIMP-1 completely protected wild-type mice against rupture but did not abort infarct healing, thus constituting a new approach to prevent cardiac rupture after acute myocardial infarction.
 ...
PMID:Inhibition of plasminogen activators or matrix metalloproteinases prevents cardiac rupture but impairs therapeutic angiogenesis and causes cardiac failure. 1050 7

Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological inhibitor of both tissue-type and urokinase-type plasminogen activators. The balance between plasminogen activators and PAI-1 plays an important role in several physiological and pathophysiological processes such as atherosclerosis or thrombosis. Because these conditions are associated with hypoxia, it was the aim of the present study to investigate the influence of low O(2) tension on the expression of PAI-1 mRNA and protein using primary cultured rat hepatocytes as a model system. We found that PAI-1 mRNA and protein were induced by mild hypoxia (8% O(2)). The hypoxia-dependent PAI-1 mRNA induction was transcriptionally regulated because it was inhibited by actinomycin D (ActD). Luciferase (LUC) reporter gene constructs driven by about 800 bp of the 5'-flanking region of the rat PAI-1 gene were transiently transfected into primary rat hepatocytes; mild hypoxia caused a 3-fold induction, which was mediated by the PAI-1 promoter region -175/-158 containing 2 putative hypoxia response elements (HRE) binding the hypoxia-inducible factor (HIF-1). Mutation of the HRE-1 (-175/-168) or HRE-2 (-165/-158) also abolished the induction by mild hypoxia. Cotransfection of a HIF-1alpha vector and the PAI-1-LUC constructs, as well as gel shift assays, showed that the HRE-2 of the PAI-1 promoter was most critical for induction by hypoxia and HIF-1 binding. Thus, PAI-1 induction by mild hypoxia via a HIF-1 binding HRE in the rat PAI-1 promoter appears to be the mechanism causing the increase in PAI-1 in many clinical conditions associated with O(2) deficiency.
 ...
PMID:Induction of the plasminogen activator inhibitor-1 gene expression by mild hypoxia via a hypoxia response element binding the hypoxia-inducible factor-1 in rat hepatocytes. 1059 62

Plasminogen activator inhibitor-1 (PAI-1) functions as an important regulator of fibrinolysis by inhibiting both tissue-type and urokinase-type plasminogen activator. PAI-1 is produced by smooth muscle cells (SMCs) in atherosclerotic arteries, but the mechanisms responsible for induction of PAI-1 in SMCs are less well understood. In cultured human aortic SMCs, PAI-1 mRNA expression and protein secretion were increased after incubation with oxidized low-density lipoprotein (LDL) and the lipid peroxidation product lysophosphatidylcholine, whereas the effects of native LDL on PAI-1 production and release were more variable and did not reach statistical significance. The effect of LDL on arterial expression of PAI-1 in vivo was also studied in an animal model. Intravenous injection of human LDL in Sprague-Dawley rats resulted in accumulation of apolipoprotein B in the aorta within 12 hours as assessed by immunohistochemical testing. Epitopes specific for oxidized LDL began to develop in the aorta 12 hours after injection of LDL and peaked at 24 hours; this peak was accompanied by intense expression of PAI-1 immunoreactivity in the media. Also, increased aortic expression of PAI-1 mRNA after LDL injection was detected by using in situ hybridization. The transcription factor activator protein-1, which is known to bind to the promoter of the PAI-1 gene, was activated in the aortic wall 24 hours after LDL injection as assessed by electrophoretic mobility shift assay. Pretreatment of LDL with the antioxidant probucol decreased expression of oxidized LDL and PAI-1 immunoreactivity and activator protein-1 induction in the aorta but did not affect expression of apolipoprotein B immunoreactivity. These findings demonstrate that LDL oxidation enhances secretion of PAI-1 from cultured SMCs and that a similar mechanism may be involved in vascular expression of PAI-1.
 ...
PMID:Oxidized LDL and lysophosphatidylcholine stimulate plasminogen activator inhibitor-1 expression in vascular smooth muscle cells. 1059 84

Plasminogen activator inhibitor-1 (PAI-1) is the only functionally labile serpin, as it converts spontaneously into a non-reactive 'latent' conformation. Several studies have suggested an important role for helix F in the functional behavior and stability of the serpins, especially for PAI-1. We constructed a mutant of PAI-1 (PAI-1-delhF) in which residues 127-158 (hF-thFs3A) were deleted. Whereas wild-type PAI-1 (wtPAI-1) exhibits inhibitory properties towards t-PA and u-PA to an extent of 60-80% of the theoretical maximum, PAI-1-delhF did not exert any detectable inhibitory properties, but behaved as a stable substrate. Prolonged incubation at 37 degrees C did not change its functional properties in contrast to wtPAI-1 that under those conditions converts to the latent conformation. In contrast to active wtPAI-1 and other substrate-type PAI-1 mutants, PAI-1-delhF showed a 3000-fold decreased binding to vitronectin. The obtained results clearly show the importance of helix F in the inhibitory activity of PAI-1. The absence of helix F apparently leads to an impaired kinetics of insertion of the reactive site loop upon interaction with its target proteinase resulting in the inability to form a stable covalent complex. Moreover, removal of helix F strongly affects the binding of PAI-1 to vitronectin.
 ...
PMID:The importance of helix F in plasminogen activator inhibitor-1. 1060 63

Macrophage migration inhibitory factor (MIF) is a cytokine that mediates inflammatory processes in a variety of tissues. In this study, we examined the expression of MIF mRNA in the mouse osteoblastic cell line MC3T3-E1, whose proliferation is promoted by various growth factors. In the subconfluent state, transforming growth factor-beta, basic fibroblast growth factor, insulin-like growth factor-II, and fetal calf serum markedly upregulated MIF mRNA expression. The upregulation of MIF mRNA was less extensive when the cells were stimulated by the same growth factors in the overconfluent state. We also investigated the expression of MIF mRNA through a whole cell cycle from G0 phase when the osteoblastic cells were synchronized by serum starvation. The MIF mRNA expression, which gradually increased from the G0 and reached its maximum at the S phase, was nonperiodic. Moreover, human recombinant MIF upregulated the expression of urokinase plasminogen activator inhibitor-1 (PAI-1) precursor mRNA in human osteoblastic Saos-2 cells. Plasminogen activator (PA) is known to play an important role in bone metabolism, for example, in activation of procollagenase or growth factors indirectly via the formation of plasmin, and in mitogenic activity for osteoblastic cells. Our results suggest that MIF modulates the proliferation of osteoblasts and, moreover, bone tissue remodeling through the PA and plasmin system.
 ...
PMID:Growth factor-induced expression of macrophage migration inhibitory factor in osteoblasts: relevance to the plasminogen activator system. 1063 79

Plasminogen activator inhibitor-1 (PAI-1), the major circulating inhibitor of urokinase [urokinase-type plasminogen activator (uPA)], has been linked to the pathogenesis of lung cancer. PAI-1 belongs to the serpin family of inhibitors and inhibits both free urokinase (uPA) and receptor-bound urokinase (uPA receptor). Although PAI-1 has been related to a poor prognosis in lung carcinoma, mechanisms that regulate its expression in human lung cancer cells are not well understood. We used cultured human small cell and non-small cell lung carcinoma cell lines as model systems to elucidate the regulatory mechanisms that control expression of PAI-1. Levels of PAI-1 protein were significantly increased in selected lung carcinoma cells compared with those in normal small-airway epithelial cells. Corresponding steady-state levels of PAI-1 mRNA were similarly increased in these cells. The half-life of PAI-1 mRNA was prolonged in these lung carcinoma cell lines after transcriptional or translational blockade. We identified a 60-kDa protein that binds the 3'-untranslated region of PAI-1, and complex formation of this binding protein with PAI-1 mRNA reciprocally correlates with mRNA stability. The findings demonstrate that expression of PAI-1 is regulated at the posttranscriptional level in small cell- and non-small cell-derived human lung carcinoma cell lines. Altered regulation of PAI-1 at the posttranscriptional level may contribute to relative overexpression by malignant lung epithelial cells. A newly identified regulatory protein that binds to the 3'-untranslated region of PAI-1 mRNA appears to be involved in the posttranscriptional regulation of PAI-1 gene expression by human lung carcinoma cells in vitro.
 ...
PMID:Posttranscriptional regulation of plasminogen activator inhibitor-1 in human lung carcinoma cells in vitro. 1064 2


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>