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)

The intrinsic activity of single-chain pro-urinary-type plasminogen activator (pro-uPA) and whether its receptor (uPAR) potentiates this activity remains controversial. In this report, the pro-uPA/uPAR-(1-281)-peptide complex in solution is shown to have equivalent plasminogen-activator activity to that of active two-chain uPA (tc-uPA). However, the activity of the complex was dependent on a synthetic tripeptide, Spectrozyme plasmin (Spl, H-D-2-aminohexanoic acid(Ahx)-hexatyrosyl-lysine-p-nitroanilide), which can also be used as a chromogenic substrate for plasmin. Furthermore, this activity could be completely suppressed by commonly used carrier proteins and detergents. The pro-uPA/uPAR-(1-281)-peptide complex at 1 nM displayed similar activity to that of tc-uPA for either [Glu1]plasminogen or [Lys77]plasminogen in chromogenic assays with Spl present as the plasmin substrate. When assayed with another plasmin substrate, S2251, the pro-uPA/uPAR-(1-281)-peptide complex was unable to activate plasminogen. The pro-uPA/uPAR-(1-281)-peptide complex and tc-uPA also showed a similar extent of plasminogen activation as measured by SDS/PAGE, when incubated with plasminogen and Spl in the presence of 100 micro M aprotinin, and plasminogen activation by pro-uPA alone was also stimulated in the presence of Spl in this assay. Activation of plasminogen by the pro-uPA/uPAR-(1-281)-peptide strictly required the presence of Spl, and pro-uPA remained in single-chain form during these assays. This activity of the pro-uPA/uPAR-(1-281)-peptide complex but not that of tc-uPA was completely inhibited by human serum albumin, bovine serum albumin, Tween-80, Triton X-100, and Pluronic-F68. Taken together, the data indicates that uPAR-(1-281)-peptide itself is not sufficient to augment pro-uPA activity and the presence of an effector molecule (e.g. Spl) is required to elicit the full plasminogen-activator activity of the pro-uPA/uPAR-(1-281)-peptide complex. It remains to be seen whether there is a physiological counterpart to this phenomenon.
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PMID:Plasminogen activation by pro-urokinase in complex with its receptor--dependence on a tripeptide (Spectrozyme plasmin). 924 34

Human ovarian adenocarcinoma cells N.1 secrete an autocrine activity that stimulates active cell death under serum-reduced conditions. To substitute the autocrine activity by a single physiological component, 28 cytokines, growth factors and biomodulators were tested [interleukin 1alpha (IL-1alpha), IL-1beta, IL-2, IL-3, IL-4, IL-6, IL-10, IL-11, stem cell factor (SCF), platelet-derived growth factor (PDGF), acid fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF-1), IGF-2, insulin, macrophage colony-stimulating factor (M-CSF), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), oncostatin, RANTES (regulated on activation normal T cell expressed and secreted), angiogenin, leukaemia inhibitory factor (LIF), erythropoietin (EPO), interferon alpha (INF-alpha), INF-gamma, transferrin, tumour necrosis factor alpha (TNF-alpha, TNF-beta and bovine serum albumin for control reasons]. In these experiments, only TNF-alpha and TNF-beta rapidly induced apoptosis. TNF-alpha and TNF-receptor 1 were expressed by N.1 cells, and the secretion of TNF-alpha was verified by enzyme-linked immunosorbent assay (ELISA). Autocrine factor-triggered apoptosis was inhibited when conditioned supernatant was preincubated with anti-TNF-alpha antibody. These findings suggested that the apoptosis-inducing component of the N.1 autocrine activity was TNF-alpha. In the presence of antisense c-myc oligonucleotides, induction of cell death by autocrine factor was partly inhibited. Autocrine factor and TNF-alpha stimulated transcription of the invasiveness-related protease plasminogen activator/urokinase mRNA (upa) with similar kinetics. When N.1 cells were exposed to purified plasminogen activator/urokinase protein (uPA), cell matrix contact was disrupted. Thus, uPA might serve a physiological role during TNF-induced apoptosis by affecting the interactions between cells and the basal membrane, thereby facilitating anoikis. This mechanistic study, which was restricted to a single human ovarian carcinoma model cell line (N.1), provides evidence that N.1 maintains the capacity to undergo c-myc-dependent apoptosis by the TNF-TNF-receptor pathway, and no additional pharmacological stimuli for induction of apoptosis are required.
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PMID:Autocrine self-elimination of cultured ovarian cancer cells by tumour necrosis factor alpha (TNF-alpha). 976 76

Investigations determined if extracellular matrix of endothelial cells (EC) is a platform for HK assembly and PK activation. In buffers containing bovine serum albumin, biotin-HK binding to ECV304 cells or their matrix requires > or = 50 microM added Zn2+. Ortho-phenanthroline or a HK domain 5 peptide blocks HK binding. Binding to umbilical vein EC or matrix, but not ECV304 cells or matrix, is mediated by cytokeratin 1. Biotin-HK binds to ECV304 cells or matrix with a Kd of 15.8 or 9.0 nM and a Bmax of 2.6 x 10(7) or 2.4 x 10(7) sites/cell, respectively. PK activation on ECV304 cells or matrix is blocked by antipain or SBTI and corn trypsin inhibitor partially inhibits kallikrein formation. PK activation occurs on ECV304 cells or matrix prepared without serum or in human factor XII deficient serum, indicating that the PK activator is not factor XIIa. EC matrix promotes plasminogen activation after the assembly of HK, PK and pro-urokinase. These studies indicate that matrix of various EC has the ability to assemble HK allowing for PK activation and subsequent activities.
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PMID:Assembly of high molecular weight kininogen and activation of prekallikrein on cell matrix. 1158 17

hK4 (prostase, KLK4), a recently cloned prostate-specific serine protease and a member of the tissue kallikrein family, is a zymogen composed of 228 amino acid residues including an amino-terminal propiece, Ser-Cys-Ser-Gln-. A chimeric form of hK4 (ch-hK4) was constructed in which the propiece of hK4 was replaced by that of prostate-specific antigen (PSA) to create an activation site susceptible to trypsin-type proteases. ch-hK4 was expressed in Escherichia coli, isolated from inclusion bodies, refolded, and purified with an overall yield of 25%. The zymogen was readily self-activated during the refolding process to generate an active form (21 kDa) of hK4 (rhK4). rhK4 cleaved the chromogenic substrates Val-Leu-Arg-pNA (S-2266), Pro-Phe-Arg-pNA (S-2302), Ile-Glu-Gly-Arg-pNA (S-2222), and Val-Leu-Lys-pNA (S-2251), indicating that rhK4 has a trypsin-type substrate specificity. The rhK4 was inhibited by aprotinin (6 kDa), forming an equimolar 27 kDa complex. rhK4 readily activated both the precursor of PSA (pro-PSA) and single chain urokinase-type plasminogen activator (scuPA, pro-uPA). rhK4 also completely degraded prostatic acid phosphatase but failed to cleave serum albumin, another protein purified from human seminal plasma. These results indicate that hK4 may have a role in the physiologic processing of seminal plasma proteins such as pro-PSA, as well as in the pathogenesis of prostate cancer through its activation of pro-uPA.
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PMID:Characterization of hK4 (prostase), a prostate-specific serine protease: activation of the precursor of prostate specific antigen (pro-PSA) and single-chain urokinase-type plasminogen activator and degradation of prostatic acid phosphatase. 1173 17

Plasmin is essential for metalloproteases activation, endothelial cell migration and degradation of the extracellular matrix. The process is common to neoangiogenesis pannus formation and cartilage degradation within arthritic joints. Since 80% of synovial cells express urokinase plasminogen activator receptor (uPAR), we investigated the inhibition of plasmin activation in a collagen-induced arthritis (CIA) mice model, by expressing a uPA/uPAR antagonist molecule (ATF) fused to human serum albumin (HSA) to extend its serum half-life. Overexpression was obtained with an adenoviral vector expressing the chimeric murine ATF-HSA. We showed that the genetic coupling did not significantly reduce the ability of the ATF moiety to interact with its receptor uPAR. The chimeric protein was detectable in the sera of injected mice 7 days following Ad-mATF-HSA injection, then decreased in parallel with the anti-HSA titer increase. Systemic Ad-mATF-HSA injection performed on day 25 following CIA induction decreased the incidence of arthritis and the severity of the disease. Moreover, synovial angiogenesis in arthritic paws was decreased after Ad-mATF-HSA gene transfer, as assessed by smooth muscle actin immunostaining. The preventive effect observed on arthritis was related to the decrease in angiogenesis, rather than inhibition of extracellular matrix degradation.
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PMID:Adenovirus-mediated gene transfer of urokinase plasminogen inhibitor inhibits angiogenesis in experimental arthritis. 1185 22

The SspB cysteine protease of Staphylococcus aureus is expressed in an operon, flanked by the sspA serine protease, and sspC, encoding a 12.9-kDa protein of unknown function. SspB was expressed as a 40-kDa prepropeptide pSspB, which did not undergo autocatalytic maturation. Activity of pSspB was reduced compared with 22-kDa mature SspB, but it was equivalent to mature SspB after incubation with SspA, which specifically removed the pSspB N-terminal propeptide. SspC abrogated the activity of pSspB when incubated in a 1:1 complex but had no effect on SspA or papain. Activity of the pSspB.SspC complex was restored when incubated with SspA, and SspC was cleaved by SspA but not pSspB. Thus, SspC maintains pSspB as an inert zymogen, and SspA is required for removal of the propeptide and inactivation of SspC. Like the papain protease family, SspB cleaved substrates with a hydrophobic amino acid at P2 but had a strong preference for arginine at P1. It did not cleave casein, serum albumin, IgG, or IgA, but it promoted detachment of cultured keratinocytes and cleaved fibronectin and fibrinogen at sites recognized by urokinase plasminogen activator and plasmin, respectively. It also processed high molecular weight kininogen in a manner resembling plasma kallikrein. Thus, SspB exhibits a novel maturation mechanism and mimics the specificity of plasma serine proteases.
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PMID:Identification of a novel maturation mechanism and restricted substrate specificity for the SspB cysteine protease of Staphylococcus aureus. 1220 24

Diabetic retinopathy and retinopathy of prematurity are among the leading causes of vision impairment throughout the world. Both diseases are characterized by pathological angiogenesis, which severely impairs vision. Extracellular proteinases play important roles in endothelial cell migration during angiogenesis. Amino-terminal fragment (ATF) is an angiostatic molecule that targets the uPA/uPAR system and inhibits endothelial cell migration. The angiostatic effect of ATF has been demonstrated in models of cancer, but has never been assessed in pathological retinal neovascularization. Endostatin also has angiostatic effects on tumor growth and retinal neovascularization. We used an adenoviral vector carrying the murine ATF (AdATFHSA) or endostatin gene coupled to human serum albumin (HSA) (AdEndoHSA) to increase the half-life of the therapeutic protein in the circulation. We induced retinopathy by exposing 7-day-old mice to high levels of oxygen. They were intravitreally injected with the vectors. Local injection of AdATFHSA or AdEndoHSA reduced retinal neovascularization by 78.1 and 79.2%, respectively. Thus, the adenovirus-mediated delivery of ATFHSA or EndoHSA reduces retinal neovascularization in a mouse model of hypoxia-induced neovascularization.
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PMID:In vivo adenovirus-mediated delivery of a uPA/uPAR antagonist reduces retinal neovascularization in a mouse model of retinopathy. 1459 83

To evaluate the potential role of the uPAR/uPA/PAI-1 system in HIV-induced blood-brain-barrier (BBB) disruption, CSF uPA-dependent plasminogen activation (PdPA) was analyzed by casein zymography, and CSF protein levels of all three molecules were measured by ELISA. CSF uPAR, but not uPA, PAI-1, or PdPA levels was significantly increased in neurologically compromised HIV+ patients. Only individual patients with severe AIDS dementia complex had increased levels of uPA (but not PAI-1) which fell upon initiation of antiretroviral therapy. The levels of all three molecules did not correlate with the CSF to serum albumin ratio suggesting not an important role in HIV-induced BBB disruption.
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PMID:Evaluation of cerebrospinal fluid uPA, PAI-1, and soluble uPAR levels in HIV-infected patients. 1588 22

Only limited comparable data are available on the clot lysis power of the clinically used plasminogen activators (PA). Here the PA were used at different clinically relevant concentrations, and the lysis of the microclots was determined. A microclot lysis assay was used to study thrombolysis by urokinase, tissue-PA (t-PA), streptokinase, plasminogen-streptokinase activator complex (PSAC), reteplase, or tenecteplase. The clot turbidity served as a tool to determine clot mass: 100 microL fresh microclots were incubated with 25 microL PA in 6% bovine serum albumin (BSA)-phosphate-buffered saline (PBS) and 100 microL BSA-PBS or pooled normal human plasma; that is, the PA were in the liquid supernatant of a plasma clot and were not entrapped in the clot, an assay system comparable to normal physiology. The turbidity was determined after 0 to 5 hours (37 degrees C) by a microtiter plate reader. The lysable clot turbidity (clot mass) was expressed in percent of 100% lysable clot control. The clot lysis activity is 100% minus the clot mass in percent. The effective doses at 50% (ED(50)) of lysis of fresh clots after 4 hours (37 degrees C) with 6% BSA or pooled normal human plasma in the clot-supernatant were urokinase 128 or 180 IU/mL; t-PA 0.3 or 0.2 microg/mL; streptokinase 215 or 1371 IU/mL; PSAC 60 or 91 U/mL; reteplase 664 or 996 U/mL; tenecteplase 0.2 or 0.2 microg/mL. The presence of a plasma thrombus with plasma supernatant increases the activity of t-PA approximately 20-fold and that of tenecteplase approximately 400-fold after 4 hours (37 degrees C), when compared to urokinase; in contrast, the lytic activity induced by reteplase decreases; i.e., the plasmin generated by reteplase is hampered on its lytic action against a thrombus. When comparing the clot lysability of microclots of 29 different donors, the only correlation (r > 0.6) was that between u-PA and t-PA. The lysability of individual clots by PA can be measured with the present routine-suited technique. It is suggested that different thrombolytic agents or concentrations thereof would have a different clinical outcome in different individuals.
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PMID:In vitro simulation of therapeutic thrombolysis with microtiter plate clot-lysis assay. 1644 31

It has been reported that ligands of the macrophage scavenger receptor (MSR) induce a range of cellular responses including urokinase-type plasminogen activator and the production of inflammatory cytokines. Although nitric oxide (NO) is an important regulatory molecule in physiological functions such as vascular homeostasis, neurotransmission, and host defense, the effect of MSR ligands on NO production from macrophages was unknown. Here, we demonstrate that the MSR ligand, fucoidan, but neither oxidized low-density lipoprotein, acetylated LDL, maleylated bovine serum albumin nor dextran sulfate induces activation of inducible nitric oxide synthase (iNOS) promoter or NO production in RAW264.7 cells. Furthermore, we investigated the molecular mechanism by which fucoidan induces iNOS promoter activation. Using different inhibitors, we showed that the stimulation of fucoidan was mediated by both the p38 mitogen-activated protein kinase and the NF-kappaB-dependent pathways. Although these two pathways were independent, heat shock protein 90 (HSP90) played a significant role in both pathways. Our previous study showed that HSP90 directly interacts with the cytoplasmic domain of MSR. These results provide the evidence that HSP90 bound to the cytoplasmic domain of MSR is implicated in MSR-mediated signal transduction. Moreover, fucoidan-induced NO production by peritoneal macrophages from MSR-knockout (MSR-/-) mice significantly decreases compared with those from wild-type mice. This is the first indication that MSR transduces the signal of fucoidan to iNOS gene expression.
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PMID:Fucoidan induces nitric oxide production via p38 mitogen-activated protein kinase and NF-kappaB-dependent signaling pathways through macrophage scavenger receptors. 1654 84


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