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)

Postlactational involution of the mammary gland is characterized by two distinct physiological events: apoptosis of the secretory, epithelial cells undergoing programmed cell death, and proteolytic degradation of the mammary gland basement membrane. We examined the spatial and temporal patterns of apoptotic cells in relation to those of proteinases during involution of the BALB/c mouse mammary gland. Apoptosis was almost absent during lactation but became evident at day 2 of involution, when beta-casein gene expression was still high. Apoptotic cells were then seen at least up to day 8 of involution, when beta-casein gene expression was being extinguished. Expression of sulfated glycoprotein-2 (SGP-2), interleukin-1 beta converting enzyme (ICE) and tissue inhibitor of metalloproteinases-1 was upregulated at day 2, when apoptotic cells were seen initially. Expression of the matrix metalloproteinases gelatinase A and stromelysin-1 and the serine proteinase urokinase-type plasminogen activator, which was low during lactation, was strongly upregulated in parallel starting at day 4 after weaning, coinciding with start of the collapse of the lobulo-alveolar structures and the intensive tissue remodeling in involution. The major sites of mRNA synthesis for these proteinases were fibroblast-like cells in the periductal stroma and stromal cells surrounding the collapsed alveoli, suggesting that the degradative phase of involution is due to a specialized mesenchymal-epithelial interaction. To elucidate the functional role of these proteinases during involution, at the onset of weaning we treated mice systemically with the glucocorticoid hydrocortisone, which is known to inhibit mammary gland involution. Although the initial wave of apoptotic cells appeared in the lumina of the gland, the dramatic regression and tissue remodeling usually evident by day 5 was substantially inhibited by systemic treatment with hydrocortisone. mRNA and protein for gelatinase A, stromelysin-1 and uPA were weakly induced, if at all, in hydrocortisone-treated mice. Furthermore, mRNA for membrane-type matrix metalloproteinase decreased after hydrocortisone treatment and paralleled the almost complete inhibition of activation of latent gelatinase A. Concomitantly, the gland filled with an overabundance of milk. Our data support the hypothesis that there are at least two distinct phases of involution: an initial phase, characterized by induction of the apoptosis-associated genes SGP-2 and ICE and apoptosis of fully differentiated mammary epithelial cells without visible degradation of the extracellular matrix, and a second phase, characterized by extracellular matrix remodeling and altered mesenchymal-epithelial interactions, followed by apoptosis of cells that are losing differentiated functions.
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PMID:Two distinct phases of apoptosis in mammary gland involution: proteinase-independent and -dependent pathways. 856 29

Liver fibrosis is a dynamic process caused by changes in not only the synthesis of matrix proteins but also their degradation. Current evidence indicates that Ito cells, when activated to a myofibroblastic phenotype, play a very active role in regulating matrix degradation in liver. This is mediated via their ability to synthesize and release several members of the matrix metalloproteinase family, a class of enzymes which are responsible for degradation of matrix proteins in the extracellular space. Activated Ito cells have been demonstrated to release prostromelysin, progelatinase A and the pro-enzyme form of interstitial collagenase. In addition, these cells can express appropriate systems for cleaving pro-metalloproteinases to active forms (e.g. the plasminogen activator system, urokinase) as well as specific tissue inhibitors of the activated metalloproteinases (TIMP). In the early phases of liver injury, enzymes with the ability to degrade components of normal liver matrix are expressed (stromelysin and gelatinase A). In contrast, in the fibrotic phase of liver injury, during which fibrillar collagens accumulate, there is little (if any) expression of interstitial collagenase but marked expression of TIMP. These findings suggest that metalloproteinase and their inhibitors play a significant role in liver injury and fibrosis.
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PMID:Role of Ito cells in the degradation of matrix in liver. 858 45

Basal as well as induced transcription from the human urokinase-type plasminogen activator gene requires an enhancer containing two elements, a combined PEA3/AP-1 and a consensus AP-1 site. The integrity of each of these binding sites as well as their cooperation is required for activating transcription. The two elements are separated by a 74-base pair cooperation mediating (COM) region required for the cooperation between the transactivating sites. The COM region contains binding sites for four different unidentified urokinase-type plasminogen activator enhancer factors (UEF 1 to 4), all four required for correct COM activity. We have purified UEF3 from HeLa nuclear extracts by several chromatographic steps including DNA affinity purification. Purification and UV cross-linking data showed that UEF3 is a complex of three polypeptides (p40, p50, and p64). Amino acid sequence from one peptide of p64 was obtained, which showed no homology to other known proteins. Both crude and purified UEF3 specifically bound to the sequence TGACAG as shown by electrophoretic mobility shifts and methylation interference studies. DNA-binding specificity of purified UEF3 was identical to that of NIP, a non-characterized factor binding and regulating multiple AP-1-regulated promoters like stromelysin and interleukin-3. Thus UEF3 appears to be a general DNA-binding factor involved in modulating the transcriptional response of AP-1 containing promoters.
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PMID:Purification and characterization of UEF3, a novel factor involved in the regulation of the urokinase and other AP-1 controlled promoters. 863

Ets-1 regulates the transcription of several genes encoding extracellular matrix proteins (ie, osteopontin and tenascin) as well as enzymes involved in degradation and remodeling of the extracellular matrix (ie, stromelysin and urokinase plasminogen activator). In the present study, we investigated the regulation of c-ets-1 in cultured rat vascular smooth muscle cells as well as in the arterial wall after balloon injury in vivo. Serum-starved smooth muscle cells exposed to serum for various time points express a major c-ets-1 mRNA transcript of 5.3 kb and minor bands of 4.0 and 2.5 kb with a peak at 2 hours after stimulation. These effects were concentration dependent. Western blotting revealed an increase in 55- and 40-kD immunoreactive ets-1 proteins in cells treated with serum for 2 hours, and binding to an oligonucleotide containing the ets-1 consensus cis-acting motif was demonstrated by electrophoretic mobility shift assay. Ets-1 mRNA abundance was induced with a peak at 2 hours after stimulation with platelet-derived growth factor-BB and with angiotensin II. There was a distinct increase of ets-1 immunoreactivity in the inner layer of the media 2 hours after balloon catheter injury of rat arteries, which declined after 6 hours and returned to the basal level 1 day after vessel wall damage. Arterial c-ets-1 mRNA content was induced with an identical time course. These findings suggest that c-ets-1 may be of importance in the mitogenic signaling pathway of smooth muscle cells grown in culture. In addition, ets-1 may play a role in the activation of smooth muscle cells in vivo after mechanical injury of the vessel wall. Because the ets-1 transcription factor activates the gene expression of a number of mRNA species involved in matrix deposition and degradation, these data are compatible with a role for ets-1 in vascular remodeling and/or cell migration.
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PMID:Regulated expression of the ets-1 transcription factor in vascular smooth muscle cells in vivo and in vitro. 863 16

Matrix proteases and the transcription factor c-Ets-1, which regulates in vitro stromelysin 1, collagenase 1, and urokinase type plasminogen activator gene promoters, are frequently expressed in invasive carcinomas. Using in situ hybridization and immunohistochemistry, we analyzed collagenase 1, stromelysins 1 and 3, matrilysin, urokinase type plasminogen activator, and c-Ets-1 gene expression on serial frozen sections of 39 intraepithelial bronchial lesions, including areas of hyperplasia, metaplasia, dysplasia, carcinoma in situ, and corresponding lung carcinomas in 13 patients. In intraepithelial lesions, expression of all matrix proteases was detected in epithelial cells. Conversely, in microinvasive or invasive lesions, a fibroblastic expression was observed. Collagenase 1 and matrilysin were expressed seldomly in intraepithelial lesions and frequently in carcinomas (p = 0.0016 and p < 0.0001, respectively). Stromelysin 1 was expressed inconsistently in 31% of intraepithelial lesions of all grades and in 50% of carcinomas. Stromelysin 3 and urokinase type plasminogen activator were expressed only, but frequently, in preinvasive lesions (dysplasia, carcinoma in situ) and in carcinomas. The expression of stromelysin 3 in fibroblasts started with dysplasia and carcinoma in situ, but was more frequent in invasive than preinvasive lesions (p = 0.0012). c-Ets-1 was more often expressed in carcinomas than in intraepithelial lesions (p < 0.0001) and was always expressed in fibroblasts. Comparing preinvasive lesions adjacent to or at a distance from squamous lung carcinoma, stromelysin 3 epithelial expression was more frequent in preinvasive lesions adjacent to invasive foci than in others (p = 0.036). We conclude that (a) both epithelial expression of matrix proteases in intraepithelial bronchial lesions and their stromal expression in microinvasive and invasive lesions suggest their role in lung tumor development; (b) c-Ets-1 does not act as a transcriptional activator for matrix proteases genes in preinvasion, although it might regulate collagenase 1 gene during lung tumor progression; and (c) matrix proteases might offer new therapeutic targets for chemoprevention of lung cancer.
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PMID:Changes in the expression of matrix proteases and of the transcription factor c-Ets-1 during progression of precancerous bronchial lesions. 868 34

The present study was carried out to characterize the patterns of expression of matrix metalloproteinases or their tissue inhibitor (TIMP-1) in normally healing, acute vs. chronic, skin wounds. In situ hybridization was performed to localize collagenase, stromelysin-1, stromelysin-2, matrilysin, urokinase plasminogen activator (uPA) and TIMP-1 mRNAs in 14 chronic venous ulcers and 10 normally healing wounds, representing different time points after wounding. Surgical wounds, made in piglets harvested at several time points, were studied as controls. Collagenase, stromelysin-1 and -2, as well as uPa, were expressed in keratinocytes in both acute and chronic wounds, while epithelial TIMP-1 mRNA was not detected in any chronic wound biopsies studied. However, TIMP-1 was expressed at the epithelial edges of both acute human and pig wounds. Our results suggest that the balance between metalloenzymes and their inhibitor TIMP-1, is disturbed, in poorly healing wounds.
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PMID:Patterns of matrix metalloproteinase and TIMP-1 expression in chronic and normally healing human cutaneous wounds. 877 59

The invasive character of squamous cell carcinoma of the head and neck represents a major challenge to the clinician since most often these tumors require extensive surgical resection impairing important physiological functions including speech and swallowing. Additionally, in many cases costly reconstructive surgery is required to repair the adverse cosmetic effects of the resective surgery. Thus, there is an urgent need to understand the molecular mechanism(s) which underlie the local and regional spread of this disease. Since the ability of tumor cells to invade into surrounding structures requires hydrolytic action much effort has been spent on identifying the hydrolases involved in this process. Some of the enzymes which have been implicated in the spread of head and neck cancer include the urokinase-type plasminogen activator and several members of the collagenase family such as type I and IV collagenases and the stromelysins synthesized either by the tumor cells or in the surrounding fibroblasts. More recent studies have addressed the mechanism(s) by which these hydrolases are overexpressed in invasive cancer. In the tumor cells themselves, work has focused on defining the transcriptional requirements for enzyme synthesis and addressing how the appropriate transcription factors are activated by signal transduction pathways. In contrast, where the hydrolases (e.g. stromelysin-2 and stromelysin-3) are produced by the fibroblasts, current investigations are directed at identifying tumor-derived growth factors which lead to the inducible expression of the enzymes in the stromal cells. The ultimate goal of these studies is to develop novel therapeutic interventions which decrease the invasive capacity of head and neck cancer leading to longer survival times and enhanced quality of life for patients afflicted with this disease.
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PMID:Invasion and metastasis. 884 80

Addition of proteolytically generated fibronectin fragments (Fn-f) to cultured cartilage tissue causes greatly enhanced release of metalloproteinases (MMPs), such as pro-stromelysin-1 (proSln-1), and suppression of proteoglycan (PG) synthesis, through release of catabolic cytokines, while native fibronectin is ineffective. We have investigated whether enhanced release of proSln-1 was due to up-regulation of pro-Sln-1 mRNA. We report the addition of a 29-kDa (amino-terminal heparin-binding Fn-f) or a 140-kDa (central cell-binding Fn-f) to bovine chondrocytes in monolayer culture causes a dose dependent increase in the expression of pro-Sln-1 mRNA and the greatly enhanced release of pro-Sln-1 protein into the culture media. Up to 700 nM pro-Sln-1 was found in the conditioned media and metabolic labeling showed that it constituted a major portion of newly synthesized protein. A potential activator of pro-Sln-1, urokinase (u-PA), was released at elevated levels in the presence of the Fn-f while other activators, tissue plasminogen activator (t-PA) and plasmin activities were not detected. Addition of these activators to conditioned media did not allow conversion of pro-Sln-1 to active Sln-1. However, aminophenyl mercuric acid activated pro-Sln-1 to a 48-kDa Sln-1 form capable of degrading PG when added to cartilage suspensions. Gelatinase A mRNA was also enhanced, suggesting that the Fn-f may induce MMPs in general. However, the major regulator of Sln-1 activity, tissue inhibitor of MMPs form 1 (TIMP-1), was not induced at the gene level. Thus, a major effect of Fn-f on chondrocytes is to up-regulate pro-Sln-1 expression at the gene level, resulting in pro-Sln-1 as a major protein product.
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PMID:Fibronectin fragments induce the expression of stromelysin-1 mRNA and protein in bovine chondrocytes in monolayer culture. 887 27

The studies described here examine the involvement of the fibrinolytic cascade and its endogenous inhibitors in the regulation of activity of matrix metalloproteinases and cartilage degradation related to non-inflammatory joint disease, like osteoarthritis. An interleukin-1-induced model of degradation using [35S]-labeled bovine and human articular cartilage explants was utilized. One goal of these studies was to compare the responses of bovine and human articular cartilage. Degradation was not inhibited by alpha 1-PI, PAI-1, alpha 2-macroglobulin, alpha 2-antiplasmin or TIMP-2, when IL-1 alone was added. Addition of human plasminogen to bovine explants, at concentrations found in human synovial fluid, increased degradation by three to four-fold. Under these conditions, the degradation was inhibited effectively by all of the endogenous inhibitors tested, indicating the presence of a cascade where activated chondrocytes are a source of u-PA. Plasminogen activated by u-PA gives plasmin, which is known to further activate pro-stromelysin. Stromelysin is essential for activation of collegenase. Not only TIMP, but also inhibitors at earlier steps of activation like PAI-1, alpha 2-antiplasmin, alpha 1-PI and alpha 2-macroglobulin inhibited degradation, and could provide cartilage protection in vivo. An experiment with human articular cartilage explants showed that very little or no degradation occurred when human articular cartilage explants were stimulated with interleukin-1 alone. Addition of human plasminogen (at physiologically relevant concentrations) resulted in significant degradation, which was inhibited in the same manner as in bovine explants, by inhibitors of the fibrinolytic cascade and TIMP. TIMP is much more efficient in human explants, indicating the limited participation of human plasmin in the degradation of human cartilage. Although speculative, it is possible that in vivo, cartilage degradation could be promoted not only by TIMP/MMP imbalance, but also accelerated by decreased levels of certain serpins in synovial fluid (e.g. PAIs, alpha 2-antiplasmin and alpha 1-PI).
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PMID:Plasminogen modulation of IL-1-stimulated degradation in bovine and human articular cartilage explants. The role of the endogenous inhibitors: PAI-1, alpha 2-antiplasmin, alpha 1-PI, alpha 2-macroglobulin and TIMP. 889 58

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


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