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)

Plasminogen activators (PA) are implicated in cell migration and tissue remodeling, two components of the bone resorption processes. Using mice with inactivated tissue PA (tPA), urokinase PA (uPA), or type 1 PA inhibitor (PAI-1) genes, we evaluated whether these processes, or their stimulation by parathyroid hormone (PTH) or 1,25-dihydroxyvitamin (1,25[OH]2D3) are dependent on these genes. Two culture models were used, one involving 19-day fetal calvariae, to evaluate the direct resorptive activity of osteoclasis, and the other involving 45Ca-labeled 17-day fetal metatarsals, in which this activity depends on preliminary (pre)osteoclast migration. PTH similarly increased (about 10-fold) PA activity in calvariae from wild-type tPA+/+ and uPA+/+ or deficient uPA-/- and PAI-/- mice; it affected only tPA, not uPA. In tPA-/- bones, the low PA levels, due to uPA, were not influenced by PTH. Calcitonin did not affect PA responses to PTH. No differences were observed between tPA+/+, tPA-/-, uPA+/+, and uPA-/- calvariae for any parameter related to bone resorption (development of lacunae, release of calcium and lysosomal enzymes, accumulation of collagenase, loss of hydroxyproline), indicating similar responses to PTH or calcitonin. The progressive 45Ca release was largely similar in cultures of tPA+/+, tPA-/-, uPA+/+, uPA-/-, PAI+/+, or PAI-/- metatarsals and it was similarly enhanced by PTH or 1,25(OH)2D3. However, uPA-/- metatarsals released 45Ca at a slower rate at the beginning of the cultures, suggesting an impaired recruitment of the (pre)osteoclasts, which migrate at that time from the periosteum into the calcified cartilage. Thus, it appears that the direct resorptive activity of the osteoclasts does not necessitate the presence of either tPA or uPA, but uPA is likely to facilitate the migration of the (pre)osteoclasts toward the mineralized surfaces. Although considerably enhanced by PTH, tPA does not mediate the actions of PTH (nor of 1,25[OH]2D3) evaluated in these models.
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PMID:Bone resorption and response to calcium-regulating hormones in the absence of tissue or urokinase plasminogen activator or of their type 1 inhibitor. 885 51

Fragments of the matrix molecule fibronectin (FN) have been shown to modulate tissue remodeling activity by inducing matrix metalloproteinases (MMPs) in synovial fibroblasts. These molecules could contribute to the tissue degradation that occurs during periodontal disease if they also modulate the expression of proteinases in cells of the periodontal ligament (PDL). We tested the hypothesis that FN and specific FN fragments induce the expression of specific proteinases in PDL cells. Using substrate zymograms, reverse zymograms and Western immunoblots, we found that PDL cells constitutively express 72 kDa gelatinase, urokinase-type plasminogen activator (uPA) and at least three inhibitors whose molecular masses correspond to those of the tissue inhibitors of metalloproteinases (TIMPs). A fourth, previously uncharacterized, proteinase inhibitor of approximately 22 kDa was also observed in some cell isolates. PDL cells, when exposed to a 120 kDa proteolytic FN fragment containing the cell-binding domain, were induced to express collagenase and stromelysin and also demonstrated an increased secretion of the serine proteinase uPA. Expression of collagenase increased with increasing concentrations (0.001 microM-1 microM) of the 120 kDa FN fragment. This fragment also induced the expression of a 20 kDa inhibitor, but not of the higher-molecular-mass inhibitors, in PDL cells. The observed alterations in proteinases were associated specifically with the 120 kDa FN fragment, since similar responses were not seen when PDL cells were exposed to either a 60 kDa heparin-binding FN fragment or a 45 kDa collagen/gelatin-binding FN fragment. PDL cells exposed to intact FN did not express the proteinases induced by the 120 kDa fragment but did express 92 kDa gelatinase and the 20 kDa proteinase inhibitor. These data suggest that FN and specific FN fragments can differentially induce the expression of proteinases in PDL cells. Thus, functional regions of FN may modulate many of the functions of PDL cells that contribute to periodontal disease, wound healing and maintenance of extracellular matrix in periodontal tissues.
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PMID:Fibronectin and fibronectin fragments modulate the expression of proteinases and proteinase inhibitors in human periodontal ligament cells. 889 25

We constructed vascular endothelial cell monolayer on a fibronectin-coated filter in a Boyden chamber and assessed the ability of 3 LL cells to penetrate through the artificial blood vessel wall. The defense of endothelial cell monolayers against the tumor cell invasion was greatly potentiated by their pretreatment with 5 or 10 micrograms/ml of brefeldin A (BFA) for 1 h (52% or 28% of control invasion). Treatment of the endothelial cell monolayers with BFA resulted in an increase in the release of inhibitory material(s) against urokinase-type plasminogen activator (u-PA) activity of 3 LL cells. Parallel experiments with the cultured endothelial cells and BFA indicated that the fungal metabolite enhanced a rate of accumulation of plasminogen activator inhibitor-1 (PAI-1) antigen, but not of tissue-type plasminogen activator antigen in the medium. The BFA-induced enhancement of PAI-1 antigen release was accompanied with the increased accumulation of the extracellular (membrane/matrix-bound) and intracellular PAI-1 antigen (219% of control at 24 h). These results suggest that BFA can strengthen the defense of vascular endothelium against tumor-cell invasion by enhancing the release and accumulation of PAI-1, which plays a critical role in the regulation of the u-PA-plasmin-collagenase activation cascade.
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PMID:Vascular endothelial cell monolayer formed on membrane filter potentiates the defense against tumor cell invasion by treatment with brefeldin A. 895 Feb 8

We studied the temporal expression of interstitial collagenase, stromelysin-1 and -2, and urokinase plasminogen activator (uPA) mRNAs by in situ hybridization in eight patients with dermatitis herpetiformis. To induce blisters, 50% potassium iodide patch tests were performed, and serial biopsy specimens were taken at 4, 12, and 24 h. Additional samples were taken from occasional spontaneous blisters. Components of the basement membrane, laminin-5, laminin-1, and type VII collagen, were examined immunohistochemically in relation to matrix metalloproteinase expression. At 12 h, when no blisters were seen, uPA mRNA was present in basal keratinocytes in five of eight samples, whereas interstitial collagenase and stromelysin-1 mRNA were not detected. At this time, immunohistochemistry failed to show changes in the basement membrane. At 24 h, uPA, collagenase, and stromelysin-1 mRNAs were present in basal keratinocytes, suggesting an activation of latent forms of the two latter enzymes by the uPA-plasmin pathway. Signal for stromelysin-2 was not detected. Furthermore, disruptions of laminin-1 and type VII collagen were evident. The data suggest that stromelysin-1 and interstitial collagenase may contribute to the degradation of basement membrane in dermatitis herpetiformis. Intracellular staining for laminin-5 co-localized with collagenase mRNA in basal keratinocytes. Because laminin-5 is essential for adhesion of keratinocytes to basement membrane and for establishment of focal adhesions on migrating cells, its production may reflect a regenerative response after the destruction of basement membrane components.
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PMID:Urokinase plasminogen activator is expressed by basal keratinocytes before interstitial collagenase, stromelysin-1, and laminin-5 in experimentally induced dermatitis herpetiformis lesions. 898 Feb 78

Clinical worsening often occurs 1 to 2 days after an intracerebral hemorrhage. Extracellular matrix proteolysis by metalloproteinases, which attack the basal lamina and open the blood-brain barrier, may be one contributing factor. Matrix metalloproteinases and plasminogen activators are increased 16 to 24 hours after a bacterial collagenase-induced intracerebral hemorrhage, suggesting that agents that block metalloproteinases may reduce the brain swelling after hemorrhage. Therefore, we injected 0.2, 0.3, 0.4, or 0.5 units bacterial collagenase intracerebrally in rats to produce an intracerebral hemorrhage. Twenty-four hours later, brain tissue was removed for measurement of brain water and electrolytes. Proteases were assayed by zymography. Treatment with a matrix metalloproteinase inhibitor, BB-1101, was begun 6 hours after the collagenase lesion, when the hematomas were formed and the secondary edema was increasing. Bacterial collagenase caused a dose-dependent hematoma at the injection site with secondary brain edema in both posterior regions. The lower bacterial collagenase doses (0.2 and 0.3 units) mainly caused brain edema in the tissue around the injection site, whereas the higher doses (0.4 and 0.5 units) also affected the opposite hemisphere. Administration of BB-1101 significantly reduced the brain water and sodium contents in regions away from the injection site in rats with 0.4 unit lesions (p < 0.05). Zymography showed an increase in 92-kDa type IV collagenase and urokinase-type plasminogen activator at 24 hours. Inhibitors of proteolytic cascade enzymes may be useful in treatment of secondary brain edema in intracerebral hemorrhage.
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PMID:Metalloproteinase inhibition blocks edema in intracerebral hemorrhage in the rat. 910 78

We describe a new principle for assessment of the activity of proteolytic enzymes of all classes and show the application of this principle for the quantitative assay of bacterial collagenase and human matrix metalloproteinases (MMPs). Central to this new principle is the presence of a proenzyme that can be activated into an active enzyme by a single proteolytic event. The regular activation sequence in the proenzyme is replaced using protein engineering by an artificial sequence recognized by the proteinase to be determined. The latter can act as an activator for the newly engineered proenzyme. In the present paper a simple colorimetric assay for the determination for MMPs is described based on this principle. With the aid of protein engineering, a modified pro-urokinase has been prepared in which the activation sequence normally recognized by plasmin (Pro-Arg-Phe-Lys upward arrowIle-Ile-Gly-Gly) has been replaced by a sequence expected to be recognized and hydrolysed by many MMPs (Arg-Pro-Leu-Gly upward arrowIle-Ile-Gly-Gly). The active urokinase resulting from activation of the modified pro-urokinase by a MMP could be measured either directly, using a specific chromogenic peptide substrate for urokinase, or indirectly via urokinase-catalysed plasminogen activation. The response of the assay to equal molar quantities of active MMPs decreases in the order MMP-2>MMP-9>MMP-1>MMP-3>MMP-7. The detection limit for MMP-9 was below 15 pM, corresponding to 3. 75x10(-15) mol per assay. Using the assay, increased MMP activity was detected in synovial tissue extracts from rheumatoid arthritis patients compared with those from osteoarthritis patients, and in stomach tumour extracts as compared with normal stomach tissue extracts.
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PMID:Modified proenzymes as artificial substrates for proteolytic enzymes: colorimetric assay of bacterial collagenase and matrix metalloproteinase activity using modified pro-urokinase. 916 91

In embryos and in human tumors, the expression of the ETS1 transcription factor correlates with the occurrence of invasive processes. Although this was demonstrated in cells of mesodermal origin, the expression of ETS1 was not detected in epithelial cells. In the present study, we show that during early organogenesis in the chick embryo, ETS1 mRNA expression was transiently induced in epithelial structures, during emigration of neural crest cells and dispersion of somites into the mesenchymal sclerotome. In contrast, the expression of ETS1 was not detected in situations where epithelial layers stayed cohesive while forming a new structure, such as the dermomyotome forming the myotome. The involvement of ETS1 in epithelial cell dissociation was examined in MDCK epithelial cells stimulated by scatter factor/hepatocyte growth factor (SF/HGF), a potent inducer of cell dissociation and motility. SF/HGF was found to stimulate ETS1 mRNA and protein expressions, and these increases coincided with the dispersion of cells and the expression of protease mRNAs, such as urokinase-type plasminogen activator and collagenase, but not with the protease inhibitor, plasminogen activator inhibitor type 1. Furthermore, we showed that SF/HGF was able to induce a transcriptional response involving ETS1 by using artificial as well as cellular promoters, such as the urokinase-type plasminogen activator and collagenase 1 promoters, containing RAS-responsive elements with essential ETS-binding sites. These data demonstrate expression of ETS1 during epithelial-mesenchymal transitions in the developing embryo and show that ETS1 can act as a downstream effector of SF/HGF in MDCK epithelial cells. Taken together, these data identify ETS1 as a molecular actor of epithelia cell dissociation.
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PMID:The ETS1 transcription factor is expressed during epithelial-mesenchymal transitions in the chick embryo and is activated in scatter factor-stimulated MDCK epithelial cells. 918 99

A new cell line MGM-1 was established from a primary tumor of the left temporal lobe with histological diagnosis of glioblastoma multiforme, removed from a 64-year-old Japanese male. The patient died of recurrence and unusual extracranial metastases of the tumor 7 months after the surgery. The cultured MGM-1 cells are spindle or polygonal in shape. After serial passages, glial fibrillary acidic protein became negative immunocytochemically in vitro. The modal chromosome number was 61-64. Doubling time and soft agar colony forming efficiency were 42.9h and 0.4%, respectively (at 25th passage). MGM-1 is a highly motile cell line in vitro and its serum-free conditioned medium is chemotactic and chemokinetic for other glioma cells. Secretion of gelatinases (probably MMP-2/72-kDa type i.v. collagenase) and MMP-9/92-kDa type i.v. collagenase) and urokinase-type plasminogen activator were also investigated. MGM-1 would therefore be useful for studying the mechanisms regulating glioma-cell motility and invasion. The MGM-1 cell line has been propagated continuously by serial passages (more than 100 passages) during the past 4 years.
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PMID:Establishment and characterization of a new human glioblastoma cell line (MGM-1) with highly motile phenotype. 923 71

Liver stellate cells (SCs) play central roles in both the storage of retinol and the development of liver fibrosis. The present study is aimed to understand the mechanism by which retinoic acid (RA, an active metabolite of retinol) enhances hepatic fibrosis in rats. We tested the effect of 9-cis-RA on several aspects in vitro rat SC cultures, including the activity of cellular plasminogen activator (PA), messenger RNA (mRNA), and protein levels of transforming growth factor-beta (TGF-beta) mRNA level of type-I procollagen, and the activity of type-I collagenase. Employing the rat liver fibrosis model produced by porcine serum, we also estimated the effect of oral administration of a stable RA analog on the progression of the fibrosis, as well as on hepatic TGF-beta contents. In vitro SC cultures, 9-cis-RA enhanced cellular PA and plasmin levels thereby induced plasmin-mediated activation of latent TGF-beta. Active TGF-beta generated self-stimulated its synthesis as well as that of collagen and suppressed the production of collagenase in an autocrine manner. In in vivo rat models, an RA analog accelerated the porcine serum-induced fibrosis by enhancing TGF-beta contents and, thus, collagen levels in the liver, although the RA analog alone was not fibrogenic. These results suggest that RA exacerbated liver fibrosis, at least in part, by inducing the activation and production of latent TGF-beta in liver SCs.
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PMID:Retinoids exacerbate rat liver fibrosis by inducing the activation of latent TGF-beta in liver stellate cells. 932 35

To elucidate potential mechanisms involved in the increased incidence of endometrial carcinomas in tamoxifen-treated patients, we examined the in-vitro effects of tamoxifen on endometrial cancer cells. The effects of tamoxifen, alone and in combination with oestradiol, on cell proliferation, plasminogen activator (PA) activity, glycogen synthase and phosphorylase activities, p53 protein concentration, and collagenase expression were assessed in two human adenocarcinoma cell lines. These lines were the oestrogen receptor-positive (Ishikawa) cells, representing a well-differentiated endometrial adenocarcinoma, and oestrogen receptor-negative (HEC-1A) cells, derived from a poorly differentiated endometrial adenocarcinoma. Tamoxifen or oestradiol alone and their combination significantly enhanced cellular proliferation of Ishikawa but not of HEC-1A cells. Both lines produced appreciable PA activity, most of which was of the urokinase type. Tamoxifen and oestradiol stimulated this activity in Ishikawa cells but not in HEC-1A cells. The effect of oestradiol was dose-dependent in a linear fashion, while tamoxifen produced a stimulation peaking at 10(-8) M and declining at higher concentrations. Tamoxifen in combination with oestradiol exhibited a synergistic effect on proliferation and on PA activity. The response of PA extended beyond the increase in proliferation, leading to higher specific activity of PA in the tamoxifen-treated cultures. In Ishikawa cells, oestradiol also increased glycogen synthase and glycogen phosphorylase activities, while tamoxifen markedly suppressed these enzymes. Oestradiol, tamoxifen, and their combination had no apparent effect on the expression of protein p53 in Ishikawa cells, or on gelatinase activity in either Ishikawa or HEC-1A cells. The present findings imply that tamoxifen produces oestrogen-agonistic effects on cell proliferation and PA activity, and oestrogen antagonistic effects on glycogen synthase and glycogen phosphorylase activities, but fails to regulate p53 and gelatinase expression. The tamoxifen-responsive systems were only observed in oestrogen-responsive adenocarcinoma cells. Thus, only certain potential oncogenic effects of tamoxifen can be simulated in vitro, and when present, these effects are enhanced in the presence of oestradiol.
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PMID:Tamoxifen exerts oestrogen-agonistic effects on proliferation and plasminogen activation, but not on gelatinase activity, glycogen metabolism and p53 protein expression, in cultures of oestrogen-responsive human endometrial adenocarcinoma cells. 946 46


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