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 production of proteolytic enzymes by osteoblasts is considered important for initiating osteoclastic bone resorption. Using the established cell line NY as an example of osteoblast-like cells, the effect of intracellular cyclic AMP (cAMP) and protein kinase C (PKC) on plasminogen activator secretion and its specific binding to the cells were investigated. HT-1080 cells were used as the control. NY cells predominantly secrete single-chain urokinase-type plasminogen activator (scu-PA) and some two-chain u-PA. Both scu-PA and u-PA were present in the cell surface and cell lysate of NY cells, and their distribution in HT-1080 cells was quite similar to that of NY cells. Exposing cells to phorbol myristate acetate (PMA) or dibutyryl cyclic AMP (db cAMP) enhanced the secretion of scu-PA and two-chain u-PA, whereas 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) decreased scu-PA secretion, indicating that it is enhanced by protein kinase C (PKC) as well as by cAMP in NY cells. On the other hand, in HT-1080 cells, PMA decreased the level of two-chain u-PA secretion into the conditioned medium. The binding assay of 125I-DFP-u-PA to NY cells revealed the presence of a single class of binding sites with a Kd of 2.23 nM and Bmax of 0.82 x 10(6) binding sites/cell. PMA however, altered neither the Kd nor the Bmax. Dibutyryl cAMP increased the Bmax 1.9 fold. Thus, NY cells secrete u-PA and express specific binding sites on the cell surface, which are modulated by cAMP and PKC.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of scu-PA secretion and u-PA receptor expression in osteoblast-like cells. 816 59

Peripheral blood monocytes exposed to bacterial products, phorbol esters, cyclic AMP, and cyclic AMP analogs express cell surface activation protein Mo3, which is the human urokinase plasminogen activator receptor (uPA-R). uPA-R is expressed by circulating monocytes from patients with multiple sclerosis (MS). We examined the role of cytoskeletal elements in the surface expression and subcellular distribution of uPA-R in nonactivated and lipopolysaccharide-activated monocytes and in monocytes from patients with MS. By using immunofluorescence techniques and confocal laser microscopy, we found that in unactivated monocytes, cytoplasmic uPA-R is found to one side of the nucleus, colocalizing with the Golgi. Upon activation with lipopolysaccharide, cytoplasmic Mo3-uPA-R becomes dispersed throughout the cytoplasm and projections concomitant with an increase in the monocyte perimeter (spreading). Cytoplasmic dispersion, as well as cell surface deposition, is dependent on microtubule integrity. Cell surface deposition of uPA-R upon activation is reduced by colchicine, which disrupts microtubules; however, once associated at the cell surface, uPA-R becomes associated with microfilaments via vinculin. Disruption of microfilaments with cytochalasin also alters surface expression of immunologically reactive uPA-R, as well as the distribution pattern. Monocytes from patients with MS display the uPA-R distribution pattern characteristic of an activated monocyte.
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PMID:Role of cytoskeletal elements in expression of monocyte urokinase plasminogen activator receptor, activation-associated antigen Mo3. 855 26

To elucidate the possible role of plasminogen activator (PA) in spermatogenesis and spermiation in mammals, we studied the hormonal regulation of PA secretion in cultured rat and mouse seminiferous tubules during defined stages of spermatogenesis. Results indicated that: (1) under basal conditions, segments of rat seminiferous tubules released primarily urokinase-type PA (uPA) at all stages of the cycle. The highest level of PA secretion occurred at stages VIIab, VIIcd and VIII. FSH, 8-bromo cyclic AMP and forskolin (FK) stimulated PA secretion, predominantly tissue-type PA (tPA). (2) In contrast, mouse seminiferous tubules secreted only tPA under basal conditions. In the presence of 50 microM MIX, seminiferous tubules at stages VII and VIII secreted higher levels of both types of PA than at the other stages. Both tPA and uPA secretion was enhanced by addition of FSH and FK to the organ culture media. (3) Segments of both rat and mouse seminiferous tubules at stages IX-XII in which the sperm residual bodies are absorbed into the Sertoli cells were also very sensitive to the addition of FSH to the organ culture. These results suggest that tPA in rat and mouse testes may play an essential role in the process of spermatogenesis and spermiation as well as in sperm residual body absorption.
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PMID:Hormonal regulation of plasminogen activator in rat and mouse seminiferous epithelium. 872 Jun 90

In order to reach the sites of inflammation, lymphocytes leave the bloodstream and migrate into peripheral tissues, in a process involving integrin-mediated adhesion to the vascular endothelium, followed by transmigration across the endothelial barrier and through the underlying interstitial matrix. We have investigated the role of the plasminogen activator/plasmin system in normal T cell migration. Receptors for urokinase plasminogen activator (uPAR) were not expressed in resting T lymphocytes, but could be efficiently induced at the mRNA and protein level by coclustering of the antigen receptor complex and beta1 or beta2 integrins, through a signalling pathway involving both protein kinase C activation and an increase in intracellular cyclic AMP. Catalytic activation of plasminogen by uPAR-expressing T cells promoted their migration through an extracellular matrix in vitro. Plasmin-induced invasion was inhibited by plasmin-and urokinase inhibitors and by anti-uPAR antibodies. Finally, cytofluorimetric and immunohistochemical analysis of primary human tumor specimens showed the presence of uPAR positive infiltrating T cells in vivo. Collectively, these findings suggest that plasminogen activation may play a role in lymphocyte migration in vivo, and that integrin-dependent expression of membrane-associated endopeptidases could represent an additional step in the regulated process of leukocyte transmigration.
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PMID:Integrin-dependent induction of functional urokinase receptors in primary T lymphocytes. 878 76

Neoplastic transformation in the normal human brain occurs as a result of the accumulation of a series of genetic alterations. These genetic alterations include the loss, gain or amplification of different chromosomes which lead to altered expression of proteins that play important roles in the regulation of cell proliferation. Several common genetic alterations at the chromosomal level (loss of 17p, 13q, 9p, 19, 10, 22q, 18q and amplification of 7 and 12q) have been observed. These alterations lead to changes in the expression of several genes; protein 53 (p53), retinoblastoma (RB), interferon (INF) alpha/beta, cyclic AMP dependent kinase number 2 (CDKN2), mutated in multiple advanced cancers 1 (MMAC1), deleted-in-colon carcinoma (DCC), epidermal growth factor receptor (EGFR), platelet derived growth factor (PDGF), platelet derived growth factor receptor (PDGFR), MDM2, GL1, CDK4 and SAS during the genesis and progression of human gliomas. Recent studies suggest that altered expression of several other genes [MET; MYC; transforming growth factor beta (TGF beta); CD44; vascular endothelial growth factor (VEGF); human neurological-related cell adhesion molecule (hNr-CAM); neuroglial cell adhesion molecule (NCAM L1); p21waf1/Cip1; TRKA; mismatch repair genes (MMR); C4-2; D2-2] and proteins [e.g., cathepsins, tenascin, matrix metalloproteases, tissue inhibitors of metalloproteases, nitric oxide synthase, integrins, interleukin-13 receptor (IL-13R), Connexin43, urokinase-type plasminogen activator receptors (uPARs), extracellular matrix proteins and heat shock proteins] are associated with the genesis of human gliomas. Taken together, these findings point to the accumulation of multiple genetic mutations coupled with extensive changes in gene expression in the etiology of human gliomas.
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PMID:Molecular changes during the genesis of human gliomas. 940 26

This study examines the effects of prostaglandin I2 (PGI2) on urokinase-type plasminogen activator (uPA) production and wound healing by human fibroblasts. Employing fibrin autography, it was found that beraprost sodium, a stable PGI2 analog, enhanced the fibrinolytic activity in media conditioned by human fibroblasts, TIG-3-20 cells. Fibrin zymography, ELISA, and Northern blot analysis confirmed that the enhanced activity was caused by an increase in uPA synthesis and secretion and a decrease in type-1 plasminogen activator inhibitor. While cycloheximide and 2',5'-dideoxyadenosine, an adenylate cyclase inhibitor, suppressed the effect of PGI2, dibutyryl cyclic AMP increased the fibrinolytic activity and uPA mRNA. These findings indicate that PGI2 promotes uPA production in TIG-3-20 cells via direct stimulation of the cyclic AMP intracellular pathway. A similar effect was observed in two other fibroblast cell lines, TIG-7-20 and TIG-7-30. Although PGI2 itself did not affect cellular proliferation, it promoted in vitro repopulation of the denuded area in a wounded monolayer. These observations suggest that PGI2 can stimulate wound healing through the enhanced production of uPA.
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PMID:Prostaglandin I2 analog enhances the expression of urokinase-type plasminogen activator and wound healing in cultured human fibroblast. 963 Jun 24

The plasminogen activators tPA and uPA, and their inhibitors, PAI-1 and PAI-2, have been associated with epithelial homeostasis and wound healing. In these studies, we investigate the effect of the steroid hormone hydrocortisone, a commonly used therapeutic modality for skin, on PAs/PAIs in serum- and plasminogen-free primary cultures of murine keratinocytes. SDS-PAGE fibrin zymography showed that addition of 1 microM hydrocortisone to cultures significantly reduced tPA fibrinolytic activity in both cell extracts and conditioned medium. uPA activity in conditioned medium was similarly inhibited. Cells were also cultured in the presence of dibutyryl cyclic AMP (dbcAMP). dbcAMP (5 mM) alone enhanced uPA and tPA fibrinolytic activity in conditioned medium, but this increase was diminished in the presence of 1 microM hydrocortisone. Immunoblots revealed a three- to fivefold induction of free PAI-1 by hydrocortisone which was partially blocked by dbcAMP. Northern blots showed that PAI-1 mRNA increased threefold 2 h after addition of hydrocortisone and remained elevated at least 8 h. In contrast, uPA and tPA mRNA were unchanged over the same time course. uPA, tPA, and PAI-1 mRNA increased in the presence of dbcAMP; levels remained elevated at least 8 h. HC suppressed the induction of uPA and tPA by dbcAMP. Studies directed at identifying plasminogen mRNA showed that in this culture system, keratinocytes produce no plasminogen mRNA either in the presence or in the absence of hydrocortisone or dbcAMP. Collectively, these results show that keratinocyte plasminogen activator activity is suppressed by hydrocortisone as a function of increased PAI-1 combined with an attenuation of PA induction by agents that increase intracellular cAMP. These results provide additional information to further define the mechanism by which glucocorticoids inhibit wound healing.
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PMID:Hydrocortisone regulates the dynamics of plasminogen activator and plasminogen activator inhibitor expression in cultured murine keratinocytes. 966 8

A cyclic AMP (cAMP)-inducible enhancer in the pig urokinase-type plasminogen activator gene located 3.4 kb upstream of the transcription initiation site is composed of three protein-binding domains, A, B, and C. Domains A and B each contain a CRE (cAMP response element)-like sequence but require the adjoining C domain for full cAMP responsiveness. A tissue-specific transcription factor, LFB3/HNF1beta/vHNF1, binds to the C domain. Mutation analyses suggest that the imperfect CRE and LFB3-binding sequences are required for tight coupling of hormonal and tissue-specific regulation. CREB and ATF1 bind to domains A and B, and this binding is enhanced upon phosphorylation by cAMP-dependent protein kinase (protein kinase A [PKA]). Analysis in a mammalian two-hybrid system revealed that CREB/ATF1 and LFB3 interact and that transactivation potential is enhanced by PKA activation. Interestingly, however, phosphorylation of CREB at Ser-133 does not contribute to its interaction with LFB3. The region of LFB3 involved in its interaction with CREB/ATF1 lies, at least partly, between amino acids 400 and 450. Deletion of this region removed the ability of LFB3 to mediate cAMP induction of the ABC enhancer but did not impair its basal transactivation activity on the albumin promoter. Thus, the two activities are distinct functions of LFB3.
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PMID:Role of tissue-specific transcription factor LFB3 in a cyclic AMP-responsive enhancer of the urokinase-type plasminogen activator gene in LLC-PK1 cells. 967 80

The underlying mechanisms responsible for both cartilage loss and subchondral bone changes in osteoarthritis (OA) remain unknown. It is becoming recognized that the extracellular matrix influences the metabolism of cells both in vivo and in vitro and can modify their responses to external stimuli. Indeed, the glycosaminoglycan/proteoglycan matrix is of major importance for the proliferation and/or differentiation of a number of cells. Here, we determined the potential role of hyaluronic acid (HA) of increasing molecular weight (MW) to alter the expression of metabolic markers and cytokine production by human osteoarthritic (OA) subchondral osteoblasts (Ob). Both 1,25(OH)(2)D(3)-induced alkaline phosphatase activity (ALPase) and osteocalcin release were increased in OA Ob when compared to normal. HA reduced osteocalcin release in OA Ob at MW of 300 and above, whereas HA failed to significantly modify ALPase. Parathyroid hormone (PTH) stimulated cyclic AMP (cAMP) formation by OA Ob. HA had a biphasic effect on this PTH-dependent activity, totally inhibiting cAMP formation at MW of 300 and 800. HA of increasing MW progressively reduced the levels of Prostaglandin E(2) (PGE(2)) and interleukin-6 (IL-6) produced by OA Ob. Interestingly, urokinase plasminogen activator (uPA) and and PA inhibitor-1 (PAI-1) levels were not significantly affected by HA of increasing MW; however, the PAI-1 to uPA ratio showed a slight, yet nonsignificant increase. Surprisingly, uPA activity was increased in OA Ob under the same conditions. Last, HA had no effect on the production of insulin-like growth factor-1 by these cells. Our data suggest that high MW HA can modify cellular parameters in OA Ob that are increased when compared to normal. The effect of HA on inflammatory mediators, such as PGE(2) and IL-6, and on uPA activity is more striking at higher MW as well. Taken together, these results could suggest that HA of increasing MW has positive effects on OA Ob by modifying their biological synthetic capacities.
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PMID:Hyaluronic acid reverses the abnormal synthetic activity of human osteoarthritic subchondral bone osteoblasts. 1455 76

Our previous studies demonstrated that a synthetic peptide encompassing residues 185-203 of the noncollagenous (NC1) domain of the alpha3 chain of type IV collagen, named tumstatin, inhibits in vitro melanoma cell proliferation and migration. In the present study, B16F1 melanoma cells were stably transfected to overexpress the complete tumstatin domain (Tum 1-232) or its C-terminal part, encompassing residues 185-203 (Tum 183-232). Tumstatin domain overexpression inhibited B16F1 in vitro cell proliferation, anchorage-independent growth, and invasive properties. For studying the in vivo effect of overexpression, representative clones were subcutaneously injected into the left side of C57BL6 mice. In vivo tumor growth was decreased by -60% and -56%, respectively, with B16F1 cells overexpressing Tum 1-232 or Tum 183-232 compared to control cells. This inhibitory effect was associated with a decrease of in vivo cyclin D1 expression. We also demonstrated that the overexpression of Tum 1-232 or Tum 183-232 induced an in vivo down-regulation of proteolytic cascades involving matrix metalloproteinases (MMPs), especially the production or activation of MMP-2, MMP-9, MMP-13, as well as MMP-14. The plasminogen activation system was also altered in tumors with a decrease of urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA) and a strong increase of plasminogen activator inhibitor-1 (PAI-1). Collectively, our results demonstrate that tumstatin or its C-terminal antitumor fragment, Tum 183-232, inhibits in vivo melanoma progression by triggering an intracellular transduction pathway, which involves a cyclic AMP (cAMP)-dependent mechanism.
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PMID:In vivo overexpression of tumstatin domains by tumor cells inhibits their invasive properties in a mouse melanoma model. 1553 Aug 61


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