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)

Transforming growth factor beta (TGF beta) treatment of rat osteoblast-rich calvarial cells or of the clonal osteogenic sarcoma cells, UMR 106-01, resulted in dose-dependent inhibition of plasminogen activator (PA) activity, and increased production of 3.2 kb mRNA and protein for PA inhibitor -1 (PAI-1). Although tissue-type PA (tPA) protein was not measured, TGF beta did not influence production of mRNA for tPA. Production of 2.3 kb mRNA for urokinase-type PA (uPA) was also increased by TGF beta in a dose-dependent manner. The effects of TGF beta on synthesis of mRNA for PAI-1 and uPA were maintained when protein synthesis was inhibited, and were abolished by inhibition of RNA synthesis. Although uPA had not been detected previously as a product of rat osteoblasts, treatment of lysates of osteoblast-like cells with plasmin yielded a band of PA activity on reverse fibrin autography, corresponding to a low Mr form of uPA. Untreated conditioned media from normal osteoblasts or UMR 106-01 cells contained no significant TGF beta activity, but activity could be detected in acidified medium. Treatment of conditioned media with plasmin resulted in activation of approximately 50% of the TGF beta detectable in acidified media. The results identify several effects of TGF beta on the PA-PA inhibitor system in osteoblasts. Net regulation of tPA activity through the stimulatory actions of several calciotropic hormones and the promotion of PAI-1 formation by TGF beta could determine the amount of osteoblast-derived TGF beta activated locally in bone. Stimulation of osteoblast production of mRNA for uPA could reflect effects on the synthesis of sc-uPA, a precursor for the active form of the enzyme.
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PMID:Transforming growth factor beta inhibits plasminogen activator (PA) activity and stimulates production of urokinase-type PA, PA inhibitor-1 mRNA, and protein in rat osteoblast-like cells. 183 80

The correlation between urokinase-type plasminogen activator (uPA) expression and tumor cell invasion and metastasis has been well documented. Urokinase converts the zymogen plasminogen to plasmin, a trypsin-like enzyme with broad substrate specificities. Net uPA activity is determined not only by the amount of the enzyme itself, but also by its state of activation and the amount of specific plasminogen activator inhibitors (PAIs) present. Both uPA and its substrate, plasminogen, can bind to cells via specific membrane-associated receptors. Expression of uPA, uPA receptor (uPAR), and PAIs is regulated by growth factors, oncogenes, and other effector molecules. In the present review we discuss the interactions of uPA with its receptor, inhibitors, and substrate and how these interactions influence malignant behavior. We also review recent reports in which investigators have used anti-catalytic antibodies and/or gene transfection to demonstrate that uPA is directly involved in tumor cell invasion and metastasis.
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PMID:The role of urokinase-type plasminogen activator in aggressive tumor cell behavior. 212 23

We have investigated whether lymphatic endothelial cells in culture produce plasminogen activators (PAs) and their inhibitors (PAIs) and if these activities can be modulated by the inflammatory cytokine Tumor Necrosis Factor alpha (TNF-alpha). Examination by reverse fibrin autography of the conditioned medium from these cells revealed a PAI of Mr 50 kDa. Also evident by fibrin autography were two species of PAs, of Mr 110 kDa and Mr 60 kDa. The 110 kDa protein co-migrated with the PA-PAI complexes and the 60 kDa protein co-migrated with tissue Plasminogen Activator (tPA). Functional and immunological assays indicated the human TNF-alpha increased the type 1 plasminogen activator inhibitor (PAI-1) in a time dependent manner. Treatment of the cells with recombinant human TNF-alpha for 24 hours resulted in a 3 to 7 fold increase in the amount of PAI released into the conditioned media. Immunoblot analysis identified the PAI in the TNF-alpha treated cell conditioned media, as PAI-1. Deposition of PAI-1 in the extracellular matrix then became apparent. TNF-alpha increased 4 fold the amount of tPA-PAI-1 complexes (Mr 110 kDa) detected in the conditioned media. Free tPA (Mr 60 kDa) decreased to 1/5 of control. Net fibrinolytic activity, as determined by a chromogenic substrate assay, decreased after TNF-alpha treatment. No urokinase type Plasminogen Activator (uPA) activity was detected in control or treated cells. This fibrinolytic activity may be important in maintaining free fluid movement in the interstitium and lymphatic vessels and in inflammatory states this potential may be decreased by the increase in PAI-1.
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PMID:Production of plasminogen activator and plasminogen activator inhibitor by bovine lymphatic endothelial cells: modulation by TNF-alpha. 223 28

We have examined the effect of thrombin on the activity of plasminogen activator (PA) and plasminogen activator-inhibitor (PA-I) in medium conditioned by primary cultures of human umbilical vein endothelial cells. PA activity was measured by fibrinolytic and esterolytic assays, and total tissue-type PA (tPA) antigen by radioimmunoassay. Net PA-I activity was assayed by titration of human urokinase esterolytic activity. Incubation of confluent endothelial cell cultures with thrombin for 24 h caused a sixfold increase in PA-I activity. The effect of thrombin was half-maximal at approximately 0.4 U/ml (less than 4 nM), and required concomitant RNA and protein synthesis. The stimulation of PA-I activity required active alpha-thrombin and was not obtained with gamma-thrombin nor with thrombin catalytically inactivated with hirudin. Because of the excess of PA-I, PA activity was not measurable in either control or thrombin-treated cells. Thrombin did, however, increase medium concentration of tPA antigen by approximately fourfold. The thrombin-induced PA-I inhibited both tPA and urokinase, did not lose activity upon acidification, and was stable to sodium dodecyl sulfate and thiol reduction. We conclude that physiologic concentrations of thrombin increase both PA-I activity and tPA antigen in medium conditioned by human umbilical vein endothelial cells. Because there was always a several-fold increase in the net activity of free PA-I, these observations suggest that the net effect of thrombin is to decrease fibrinolytic activity in human endothelial cells. Thus, thrombin, in addition to its role in coagulation, may protect clots from premature lysis by increasing the amount of a specific fibrinolytic inhibitor.
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PMID:Thrombin induction of plasminogen activator-inhibitor in cultured human endothelial cells. 241 59

Baseline cellular plasminogen activator (PA) activity, and the cellular proteins responsible for variations in PA activity were evaluated in three human prostate carcinoma cell lines. Net PA activity in the cell lines PC-3, DU-145, and LNCaP was measured using a plasminogen-dependent fibrin lysis assay. These three cell lines were then analyzed to determine the specific protein(s) responsible for differences in PA activity. mRNA and protein levels of cellular urinary PA (uPA), tissue PA (tPA), PA inhibitor 1 (PAI1), PA inhibitor 2 (PAI2), and uPA receptor (uPAr) were measured using Northern analysis and ELISA assays. Net cellular PA activity in the three cell lines varied over a 3-fold range (PC3 > DU145 >> LNCaP). Net PA activity in the fibrinolysis assay demonstrated a direct correlation with mRNA transcript levels of uPA, tPA, PAI1, and uPAr (PC-3 > DU-145 > LNCaP). uPA protein was identified in both the PC-3 and the DU-145 lines. tPA, PAI1, and PAI2 proteins were identified only in PC-3 cells. In general, cellular protein levels correlated with mRNA levels. These findings demonstrate that prostate carcinoma cell lines vary in their net PA activity. This variability results from both qualitative and quantitative differences in the cellular expression of PA regulatory proteins.
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PMID:Diversity and modulation of plasminogen activator activity in human prostate carcinoma cell lines. 747 84

In the present study, we have examined the influence of transforming growth factor-alpha (TGF alpha) and FSH in vitro on the granulosa cell plasminogen activator (PA) system accompanying cell proliferation and differentiation during follicular development. Undifferentiated and differentiated rat granulosa cells from diethylstilbestrol (DES)- and eCG-treated immature rats, respectively, were cultured in medium containing FSH (400 ng/ml), TGF alpha (0.5-50 ng/ml), and/or transforming growth factor-beta (TGF beta; 25-100 ng/ml). Net secreted PA (PAs) and cell-associated PA (PAc) activities were higher in differentiated cells and were stimulated by TGF alpha (but not by TGF beta) in a concentration-dependent manner. Basal and FSH-stimulated PAs was higher than PAc and accounted for 70-80% of the total PA activity in both cell preparations. FSH-stimulated PA activities increased in undifferentiated granulosa cells but decreased in differentiated cells with increased duration of culture. A biphasic effect (stimulatory in the first 24 h and inhibitory thereafter) of TGF alpha on FSH-induced PA activities was observed in the cultures of undifferentiated granulosa cells. Whereas both urokinase (uPA) and tissue (tPA) PA appeared to be present in cultures of granulosa cells from DES-treated rats, only tPA could be detected in those from eCG-treated animals. TGF alpha increased basal tPA activity at both stages of follicular development but inhibited activities of uPA in undifferentiated granulosa cells, irrespective of the presence of FSH. This growth factor stimulated basal progesterone (P) and 20 alpha-dihydroprogesterone (20 alpha-OH-P) secretion (an index of granulosa cell differentiation), the effect being more pronounced at the late stage of follicular development.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Follicular stage-dependent regulation of rat granulosa cell plasminogen activator system by transforming growth factor-alpha in vitro. 771 Dec 10

Baseline cellular plasminogen activator (PA) activity, the cellular proteins responsible for variations in PA activity and the effect of cellular PA activity on cellular adherence to and lysis of fibrin substrate were evaluated in three human transitional carcinoma cell lines. Net PA activity in the cell lines 253J, 639V and 647V was measured using a chromogenic substrate assay. These lines were then analyzed to determine the specific protein(s) responsible for differences in PA activity. mRNA and protein levels of cellular uPA, tPA, PAI1 and PAI2 were measured using Northern blot analysis and ELISA assays. Intact cells were used in an in vitro fibrinolysis assay so as to correlate cell biology with protein and mRNA level observations. Net cellular PA activity in the three cell lines varied over a 20-fold range (253J > 639V > 647V). Net PA activity demonstrated a direct correlation with mRNA transcript and protein levels of uPA/low levels of tPA mRNA were detected in the 253J line. However, tPA protein was not detectable in any of the lines. Both PAI1 and PAI2 were detected in varying amounts in each of the three cell lines. In vitro assays demonstrated a direct correlation between net PA activity and plasminogen dependent fibrin substrate lysis. Cellular adherence to fibrin varied as an inverse function of net PA activity. These findings suggest that variations in cellular uPA levels are principally responsible for variations in PA activity between cell lines. Variations in net PA activity are in turn reflected at the cellular level by differences in ECMP substrate lysis and cellular adherence to fibrin.
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PMID:Diversity and modulation of plasminogen activator activity in human transitional carcinoma cell lines. 818 98

Fibrin is an important mediator of injury in severe proliferative forms of glomerulonephritis (GN). Normal glomeruli express fibrinolytic activity, which may protect against the injurious effects of fibrin deposition. Changes in glomerular fibrinolytic activity (GFA) may play an important role in modulating fibrin accumulation in GN. To study the changes in GFA associated with fibrin deposition in GN, autologous phase anti-glomerular basement antibody initiated GN (anti-GBM GN) was studied in rabbits. Net GFA was significantly reduced in association with glomerular fibrin deposition (1.3 +/- 0.8 ng fibrin lysed/10(3) glomeruli/2 hr, normal 57.1 +/- 25.4 ng fibrin lysed/10(3) glomeruli/2 hr, P < 0.02). Reduced GFA in fibrin associated GN was associated with decreased expression of tissue type plasminogen activator (tPA) and increased expression of plasminogen activator inhibitor type-1 (PAI-1) and glomerular macrophage infiltration. In a fibrin independent model of anti-GBM induced GN (heterologous phase), with equivalent injury (proteinuria), net GFA was increased (174 +/- 64 ng fibrin lysed/10(3) glomeruli/2 hr). This was associated with increased tPA and uPA, and decreased PAI-1 in the absence of significant macrophage infiltration. These studies demonstrate that fibrin deposition in GN is associated with a net reduction of GFA, attributable to reduced expression of plasminogen activators and augmentation of PAI-1. Reduction of GFA may potentiate glomerular fibrin deposition and consequent glomerular injury. The association between glomerular macrophage influx and reduction in GFA suggests that this change may be directed by macrophages.
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PMID:Glomerular fibrinolytic activity in anti-GBM glomerulonephritis in rabbits. 823 Oct 28

By virtue of their unique chronic expression of tissue factor, the primary initiator of hemostasis, decidualized endometrial stromal cells are capable of significant thrombin generation after vascular disruption. In addition to its potent procoagulant effects, thrombin modifies endothelial and glomerular cell fibrinolytic activity. Therefore, we evaluated whether thrombin affected the expression of endometrial stromal cell urokinase-type (uPA) and tissue-type (tPA) plasminogen activators and their primary inhibitor, type 1 plasminogen activator inhibitor (PAI-1), and whether ovarian steroids modulated putative thrombin effects. Confluent stromal cell cultures were incubated in a defined medium containing vehicle control, 10(-8) mol/L estradiol (E2), 10(-7) mol/L medroxyprogesterone acetate (MPA), or E2 plus MPA for 4 days. The medium was then collected and exchanged for medium containing the corresponding steroids with or without thrombin and the specific thrombin inhibitor, D-phenyl-alanyl-propyl-arginine-chloromethyl ketone, for an additional 24 h. The conditioned medium was then collected and analyzed for immunoreactive (ir) uPA, tPA, and PAI-1 by enzyme-linked immunosorbent assay and for PA activity by chromogenic assay, whereas Northern analysis of the cells was employed to evaluate the expression of thrombin receptor, uPA, tPA, and PAI-1 messenger ribonucleic acid (mRNA) species. The latter studies revealed that confluent cultures incubated in defined medium expressed the 3.45-kilobase thrombin receptor message. Steady state levels of thrombin receptor mRNA were unaffected by exogenous steroids. Thrombin added in the absence of exogenous steroids elevated concentrations of ir tPA, uPA, and PAI-1 compared with control cultures. Conversely, in the absence of added thrombin, MPA added alone or together with E2 inhibited levels of ir tPA and uPA while stimulating PAI-1 levels despite the lack of a response to E2 alone. Interestingly, thrombin counteracted this progestin inhibition of tPA and uPA expression and augmented the progestin-enhanced expression of PAI-1. Northern analysis revealed that steady state levels of tPA and uPA mRNA were also enhanced by thrombin in both control and steroid-containing cultures. Net PA activity reflects the balance between PA and PAI-1. In the absence of thrombin, there is virtually no detectable tPA activity and minimal uPA activity in progestin-exposed cultures. However, thrombin elicited significant increases in tPA and uPA activity in control and E2-treated cultures. Despite the molar excess of PAI-1 in MPA-treated and E2- plus MPA-treated cultures, thrombin reversed progestin inhibition of PA activity. Predictably, the addition of D-phenyl-alanyl-propyl-arginine-chloromethyl ketone, blocked the effects of thrombin on PAI-1, tPA, and uPA protein and mRNA expression and PA activity. In summary, thrombin enhances endometrial stromal cell fibrinolytic and extracellular matrix-degrading protease activity in vitro. Such processes occurring in vivo would probably play a role in menstruation and abnormal uterine bleeding.
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PMID:Effects of thrombin on steroid-modulated cultured endometrial stromal cell fibrinolytic potential. 855 Jul 36