Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Despite the ubiquitous presence of basic fibroblast growth factor (bFGF) in normal tissues, endothelial cell proliferation in these tissues is usually very low, suggesting that bFGF is somehow sequestered from its site of action. Immunohistochemical staining revealed the localization of bFGF in basement membranes of diverse tissues, suggesting that the extracellular matrix (ECM) may serve as a reservoir for bFGF. Moreover, functional studies indicated that bFGF is an ECM component required for supporting endothelial cell proliferation and neuronal differentiation. We have found that bFGF is bound to heparan sulfate (HS) in the ECM and is released in an active form when the ECM-HS is degraded by heparanase expressed by normal and malignant cells (i.e. platelets, neutrophils, lymphoma cells). It is proposed that restriction of bFGF bioavailability by binding to ECM and local regulation of its release provide a novel mechanism for neovascularization in normal and pathological situations. The subendothelial ECM contains also tissue type- and urokinase type-plasminogen activators which participate in cell invasion and tissue remodeling. These results and studies on the properties of other ECM-immobilized enzymes (i.e. thrombin, plasmin, lipoprotein lipase) and growth factors (GM-CSF, IL-3, osteogenin), suggest that the ECM provides a storage depot for biologically active molecules which are thereby stabilized and protected. This may allow a more localized and persistent mode of action, as compared to the same molecules in a fluid phase.
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PMID:Extracellular matrix-resident basic fibroblast growth factor: implication for the control of angiogenesis. 171 29

The effect of plasminogen on the ability of highly metastatic ESb mouse lymphoma cells to degrade heparan sulfate (HS) in the subendothelial extracellular matrix (ECM) was studied. A metabolically sulfate-labeled ECM was incubated with the lymphoma cells, and labeled degradation products were analyzed by gel filtration on Sepharose 6B. Heparanase-mediated release of low-Mr (0.5 less than Kav less than 0.85) HS cleavage products was stimulated fourfold in the presence of plasminogen. Incubation of plasminogen alone with the ECM resulted in its conversion into plasmin, which released high-Mr (Kav less than 0.33) labeled proteoglycans from the ECM. Heating the ECM (80 degrees C, 1 hr) abolished its ability to convert plasminogen into plasmin, yet plasminogen stimulated, through its activation by the ESb plasminogen activator, heparanase-mediated release of low-Mr HS fragments. Heparin inhibited both the basal and plasminogen-stimulated degradation of HS side chains but not the total amount of labeled material released from the ECM. In contrast, aprotinin inhibited the plasminogen-stimulated release of high- as well as low-Mr material. In the absence of plasminogen, degradation of heated ECM by ESb cells was completely inhibited by aprotinin, but there was only a partial inhibition of the degradation of native ECM and no effect on the degradation of soluble HS proteoglycan. These results demonstrate that proteolytic activity and heparanase participate synergistically in the sequential degradation of ECM HS and that the ESb proteolytic activity is crucial for this degradation when the ECM-associated protease is inactivated. Plasminogen may serve as a source for the proteolytic activity that produces a more accessible substrate to the heparanase.
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PMID:Involvement of both heparanase and plasminogen activator in lymphoma cell-mediated degradation of heparan sulfate in the subendothelial extracellular matrix. 242 87

A highly metastatic variant (ESb) of a methylcholanthrene-induced T lymphoma elaborates a heparan sulfate (HS) degrading endoglycosidase (heparanase) to a much higher extent than its non-metastatic parental subline (Eb). Whereas a serum-free medium conditioned by either subline contained a trypsin-like serine protease, heparanase activity was detected only in the ESb-conditioned medium (CM). ESb CM was incubated with a naturally produced, sulfate-labelled subendothelial extracellular matrix (ECM) or with a soluble, high-MW labelled proteoglycan first released from the ECM by incubation with Eb CM or with the partially purified ESb protease. Sulfate labelled degradation products were analyzed by gel filtration on Sephrose 6B. The optimal pH for degradation of ECM-bound HS was 6.2 as compared to pH 5.2 for degradation of the soluble proteoglycan. Heparanase-mediated degradation of both ECM-bound and soluble HS was inhibited by heparin. Addition of either trypsin, plasmin or to a lower extent, the purified ESb protease, stimulated between 5- and 20-fold the ESb CM-mediated degradation of ECM-bound HS but had no effect on heparanase-mediated degradation of the soluble proteoglycan. This stimulation was inhibited in the presence of heparin or protease inhibitors. These results indicate that both a protease and heparanase are involved in the ESb-mediated degradation of ECM-bound HS and that one enzyme produces a more accessible substrate for the next enzyme. This sequential cleavage is characteristic of degradation of a multimolecular structure such as the subendothelial ECM and hence cannot be detected in studies with its isolated constituents.
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PMID:Sequential degradation of heparan sulfate in the subendothelial extracellular matrix by highly metastatic lymphoma cells. 315 49

We have determined whether macrophage derived-foam cells, a prominent component of the atherosclerotic lesion, express more urokinase-type plasminogen activator (uPA) and whether their ability to generate plasmin stimulates the release of matrix-bound growth factors. Steady state levels of uPA mRNA and both membrane and intracellular uPA activities were significantly increased in foam cells. When cultured on cell-derived matrices containing bound 125I-basic fibroblast growth factor (bFGF), both macrophage and foam cells released intact 125I-bFGF into their media. The release of 125I-bFGF by either cell was significantly enhanced in the presence of plasminogen. However, foam cells, which expressed more membrane uPA, released more 125I-bFGF than control cells. The release of matrix-bound bFGF was independent of heparanase activity, since neither macrophage nor foam cells degraded 35SO4-labeled heparan sulfate proteoglycans. In addition, media derived from foam cells cultured on cell-derived matrices in the presence of plasminogen had increased levels of transforming growth factor (TGF) beta activity as compared to cells grown in the absence of plasminogen. In contrast, plasminogen had no effect on TGF-beta activity recovered in the media of foam cells grown on plastic. Moreover, when macrophage were cultured on matrices containing bound 125I-TGF-beta, the release of labeled TGF-beta was increased in the presence of plasminogen. This is the first demonstration that foam cells can release two important growth regulators, bFGF and TGF-beta, from the extracellular matrix, and provides a mechanism by which macrophage and foam cells can stimulate atherosclerotic lesion development.
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PMID:Macrophage and foam cell release of matrix-bound growth factors. Role of plasminogen activation. 850 19

Basic fibroblast growth factor (bFGF or FGF-2) is an angiogenic and pleiotropic growth factor involved in the proliferation and differentiation of numerous cell types. It is expressed mostly in tissues of mesoderm and neuroectoderm origin, and is thought to play an important role in the mesoderm induction. Although hematopoietic cells derive from the mesoderm, relatively few studies have, until recently, addressed the role of FGF-2 in hematopoiesis. FGF-2 is expressed in cells of the bone marrow including stromal cells, and possibly cells from several hematopoietic cell lineages. It is stored in the bone marrow extra-cellular matrix and released by enzymes such as heparanase, plasmin, or phospholipase C and D. FGF-receptors (FGF-Rs) are expressed in leukemic cell lines and in hematopoietic cells. FGF-2 positively regulates hematopoiesis, by acting on stromal cells, on early and committed hematopoietic progenitors, and possibly on some mature blood cells. The action of FGF-2 is most likely indirect since its action, on megakaryocytopoiesis for example, is abrogated by anti-IL6 antibodies. It synergizes with hematopoietic cytokines, or antagonizes the negative regulatory effects of TGF-beta. Taken together, these results demonstrate that FGF-2 is a potent hematopoietic growth factor that is likely to play an important role in physiological and pathological hematopoiesis.
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PMID:The role of fibroblast growth factor-2 (FGF-2) in hematopoiesis. 871 68

This assay employs a biotinylated heparan sulfate glycosaminoglycan (HSGAG) substrate that is covalently linked to the surface of 96-well immunoassay plates. The ratio of biotin:HSGAG and the coating concentration of substrate bound to the wells have been optimized and allow removal of biotin HSGAG within 60 min of incubation at 37 degrees C in assay buffer with a standard dilution of bacterial heparitinase or platelet heparanase. Loss of biotin signal from the well surface is detected on incubation with peroxidase-streptavidin followed by color development using 3,3',5,5'-tetramethylbenzidine as the peroxidase substrate. The new assay allows specific detection of heparanase activity in multiple samples in a total time of 3 h including a 1-h substrate digestion step and is a significant improvement with regard to sensitivity, specificity, and ease of handling of multiple samples compared to other described assays. Heparanase specifically degrades the biotinylated HSGAG substrate, when used with an optimized assay buffer. A range of enzymes including collagenase, trypsin, plasmin, pepsin, chondroitinases, hyaluronidase, and neuraminidase show no effect on the substrate under optimized assay conditions. The covalent linkage of the substrate to the well prevents leaching of substrate and allows preparation and long-term storage of substrate-coated plates. The assay can be used to detect heparanase levels in clinical samples and cell culture supernatants and is ideal as a screening method for antagonists of enzyme activity.
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PMID:A multiwell format assay for heparanase. 1292 26

Sun-exposed skin is characterized by superficial changes such as wrinkles, sagging and pigmentary changes, and also many internal changes in the structure and function of epidermis, basement membrane (BM) and dermis. These changes (so-called photoageing) are predominantly induced by the ultraviolet (UV) component of sunlight. Epidermis of UV-irradiated skin produced several enzymes such as matrix metalloproteinases (MMPs), urinary plasminogen activator (uPA)/plasmin and heparanase, which degrade dermal collagen fibres and elastic fibres in the dermis, and components of epidermal BM. The BM at the dermal-epidermal junction (DEJ) controls dermal-epidermal signalling and plays an important role in the maintenance of a healthy epidermis and dermis. BM is repetitively damaged in sun-exposed skin compared with unexposed skin, leading to epidermal and dermal deterioration and accelerated skin ageing. UV exposure also induces an increase in vascular endothelial growth factor (VEGF), an angiogenic factor, while thrombospondin-1 (TSP-1), an anti-angiogenic factor, is decreased; these changes induce angiogenesis in papillary dermis with increased migration of elastase-positive leucocytes, leading to dermal elastic fibre damage. Elastic fibres, such as oxytalan fibres in papillary dermis, are associated with not only skin resilience, but also skin surface texture, and elastic fibre formation by fibroblasts is facilitated by increased expression of fibulin-5. Thus, induction of fibulin-5 expression is a damage-repair mechanism, and fibulin-5 is an early marker of photoaged skin. UV-induced skin damage is cumulative and leads to premature ageing of skin. However, appropriate daily skincare may ameliorate photoageing by inhibiting processes causing damage and enhancing repair processes.
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PMID:Characterization and mechanisms of photoageing-related changes in skin. Damages of basement membrane and dermal structures. 2753 97