Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.7 (plasmin)
9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Degradation of adhesive glycoproteins by plasmin is implicated in cell migration. In this study, we further explored the role of plasminogen activation in cell adhesion and survival and show that uncontrolled plasminogen activation at the cell surface may induce cell detachment and apoptosis. We hypothesized that this process could be prevented in adherent cells by expression of protease nexin-1, a potent serpin able to inhibit thrombin, plasmin, and plasminogen activators. Using two- and three-dimensional culture systems, we demonstrate that Chinese hamster ovary fibroblasts constitutively express tissue-type plasminogen activator and efficiently activate exogenously added plasminogen in a specific and saturable manner (K(m) = 46 nm). The formation of plasmin results in proteolysis of fibronectin and laminin, which is followed by cell detachment and apoptosis. Protease nexin-1 expressed by transfected cells significantly inhibited the activity of plasmin and tissue-type plasminogen activator via the formation of inhibitory complexes and prevented cell detachment and apoptosis. In conclusion, protease nexin-1 may be an important anti-apoptotic factor for adherent cells. This cell model could be a useful tool to evaluate therapeutic agents such as serpins in vascular pathologies involving pericellular protease-protease inhibitor imbalance.
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PMID:Protease nexin-1 inhibits plasminogen activation-induced apoptosis of adherent cells. 1469 93

A serine proteinase with kallikrein-like activity (LV-Ka) has been purified to homogeneity from bushmaster snake (Lachesis muta muta) venom. Physicochemical studies indicated that LV-Ka is a single chain glycoprotein with a molecular mass (Mr) of 33 kDa under reducing conditions which was reduced to 28 kDa after treatment with N-Glycosidase F (PNGase F). LV-Ka can be bounded and neutralized by serum alpha2-macroglobulin (alpha2-M), a prevalent mammalian protease inhibitor that is capable of forming a macromolecular complex with LV-Ka (Mr >180 kDa). Cleavage of alpha2-M by the enzyme resulted in the formation of 90-kDa fragments. The proteolytic activity of LV-Ka against dimethylcasein could be inhibited by alpha2-M, and the binding ratio of the inhibitor:enzyme complex was found to be 1:1. The Michaelis constant, Km, and catalytic rate constant, kcat, of LV-Ka on four selective chromogenic substrates were obtained from Lineweaver-Burk plots. LV-Ka exhibits substrate specificities not only for the glandular kallikrein H-D-Val-Leu-Arg-pNA (S-2266) but also for the plasmin substrates S-2251 and Tos-Gly-Pro-Lys-pNA. Bovine kininogen incubated with LV-Ka generated a polypeptide that dose dependently contracted mesenteric arterial rings from spontaneously hypertensive rats (SHR) in a similar way as bradykinin (BK) does. As it happens with BK, LV-Ka generated polypeptide was inhibited by HOE-140, a bradykinin B2-receptor antagonist and by indomethacin, a cyclo-oxygenase inhibitor. These results strongly suggest that the polypeptide generated by LV-Ka by cleavage of bovine kininogen is bradykinin. In addition, our studies may help to understand the mechanism of action involved in hypotension produced by envenomation of bushmaster snake.
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PMID:Biochemical properties of a bushmaster snake venom serine proteinase (LV-Ka), and its kinin releasing activity evaluated in rat mesenteric arterial rings. 1553 59

alpha2-Macroglobulin (alpha2M) is a protease inhibitor that has separate binding sites for transforming growth factor-beta (TGF-beta) and beta-amyloid peptide (Abeta), both of which have been identified in the beta2M sequence. In the 3D-structure of alpha2M, TGF-beta occupies the alpha2M central cavity, overlapping with the space that can accommodate up to two molecules of protease. As a result, ternary alpha2M-protease complexes (2 mol protease/mol alpha2M) have been reported to not bind TGF-beta. The goal of the present study was to test whether binding of Abeta to alpha2M is controlled by steric constraints imposed by associated proteases, similarly to TGF-beta. We confirmed that binary alpha2M-trypsin complex (1 mol trypsin/mol alpha2M) binds increased amounts of TGF-beta1, compared with native alpha2M, while ternary alpha2M-trypsin complex binds substantially decreased amounts of TGF-beta1. By contrast, Abeta-binding to binary and ternary alpha2M trypsin complex was equivalent. In both cases, binding was substantially increased compared with the negligible level observed with native alpha2M. Plasmin is a large protease (Mr approximately 82,000) that substantially occupies the alpha2M central cavity; however, alpha2M-plasmin complex also bound increased amounts of Abeta, compared with native alpha2M. We conclude that Abeta accesses its binding site, in alpha2M, from outside the alpha2M central cavity. The TGF-beta- and Abeta-binding sites are spatially separated not only in the primary sequence of alpha2M, but also in the 3D-structure.
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PMID:Beta-amyloid peptide binds equivalently to binary and ternary alpha2-macroglobulin-protease complexes. 1600 50

Evidence suggests that fibrin deposit is related to severity of glomerulonephropathy. Fibrin is considered to play an active role beyond a haemostatic plug or temporary matrix in response to injury. We have reported that fibrin induced specific morphological changes and up-regulated intercellular adhesion molecule-1 expression of glomerular endothelial cells (GECs). Changes of gelatinases activity have been implicated playing a prominent role in glomerular diseases involving matrix turnover. This study examined whether overlying fibrin influences the expression of gelatinase A and B in cultured human GECs and mechanism underlying the activation. No gelatinase activity was detectable in supernatant of cultured GECs; however, physiological concentration of fibrin (0.5-2.0 mg/ml) induced a dramatic expression of activated MMP-2 and MMP-9 at both mRNA and protein level in a dose and time dependent manner. Increased mRNA level of membrane-type 1 matrix metalloproteinases (MT1-MMPs) was also found. Interestingly, we observed that fibrin also induced the expression of tissue type plasminogen activator (tPA), urokinase type plasminogen activator (uPA) and plasminogen activator inhibitor-1 by casein zymographic and reverse zymographic analysis. Fibrin plate assay revealed the net activity was PA predominant. Serine protease inhibitor aprotinin blocked the conversion of pro-gelatinase A and B to their active forms. The results demonstrate that overlying fibrin increased the secretion of gelatinase A and B from GECs. PA/plasmin proteolytic pathways contributed to the activation of gelatinases.
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PMID:Activation of gelatinases by fibrin is PA/plasmin system-dependent in human glomerular endothelial cells. 1613 29

The goal of this work was to demonstrate that aprotinin conjugated to fibrinogen could (1) maintain its function and (2) control fibrin degradation. Using the chick chorioallantoic membrane (CAM) assay, we found that blood vessels did not directly invade fibrin constructs containing immobilized fibroblast growth factor-2. Because the fibrin quickly degraded within approximately 5 days, we hypothesized that controlling fibrinolysis may improve direct blood vessel invasion. Aprotinin, a protease inhibitor typically added to slow fibrinolysis, is a small protein and can diffuse out of the gel resulting in the loss of fibrinolysis protection. Therefore, using a novel synthesis strategy, aprotinin and a fluorescent reporter, Cy3, were chemically conjugated to fibrinogen. In vitro microplate absorbance assays showed that the conjugated aprotinin was able to inhibit plasmin-mediated fibrin degradation and that its activity was comparable to equimolar levels of soluble, nonconjugated aprotinin. Additionally, we found that fibrinolysis rates could be tuned by varying the level of conjugated aprotinin within the gel. The conjugated aprotinin also demonstrated functionality in vivo. In the chick CAM assay, fibrin gels containing conjugated aprotinin were approximately 5 times larger than gels containing soluble aprotinin after 4 days. Also, in support of our hypothesis, we found that immobilized aprotinin within fibrin gels demonstrated substantial blood vessel invasion.
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PMID:Immobilization of aprotinin to fibrinogen as a novel method for controlling degradation of fibrin gels. 1743 24

Plasma proteins such as early complement components and IgM are involved in the removal of late apoptotic or secondary necrotic (sn) cells. We have recently described how a plasma protease that could be inhibited by the protease inhibitor aprotinin was essential to remove nucleosomes from sn cells. An obvious candidate, plasmin, did indeed have nucleosome-releasing factor (NRF) activity. However, recalcified plasma (r-plasma) retained its NRF activity after plasminogen depletion, which suggests the existence of another protease responsible for NRF activity in plasma. In this study we have used size-exclusion and anion-exchange chromatography to purify the protease responsible for NRF activity in plasma. SDS-PAGE analysis of chromatography fractions containing NRF activity revealed a protein band corresponding with NRF activity. Sequence analysis showed this band to be factor VII-activating protease (FSAP). We developed monoclonal antibodies to FSAP and were able to completely inhibit NRF activity in plasma with monoclonal antibodies to FSAP. Using affinity chromatography we were able to purify single-chain (sc) FSAP from r-plasma. Purified scFSAP efficiently removes nucleosomes from sn cells. We report that factor VII-activating protease may function in cellular homeostasis by catalyzing the release of nucleosomes from secondary necrotic cells.
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PMID:Nucleosome-releasing factor: a new role for factor VII-activating protease (FSAP). 1875 48

Pleiotrophin is an 18 kDa secreted polypeptide growth factor with direct pro-angiogenic and tumorigenic properties. Pleiotrophin is a substrate for proteolytic enzymes, such as plasmin, leading to proteolytic fragments with distinct activities on endothelial cell activation in vitro or angiogenesis in vivo. Aprotinin is a naturally occurring broad spectrum protease inhibitor, used widely in cardiac surgery due to its ability to inhibit plasmin and reduce perioperative bleeding. Since we have seen that aprotinin inhibits proteolysis of pleiotrophin by plasmin, the aim of the present study was to evaluate the possible role of pleiotrophin in the effects of aprotinin on angiogenesis and human endothelial cell migration. Our data demonstrate that aprotinin, in a concentration-dependent manner, is angiogenic in the chicken embryo chorioallantoic membrane assay in vivo and induces human endothelial cell migration in vitro. Aprotinin inhibits pleiotrophin proteolysis and induces expression and secretion of pleiotrophin through an AP-1-dependent transcriptional activation of the pleiotrophin gene, and pleiotrophin seems to mediate the stimulatory effects of aprotinin on cell migration through its receptor protein tyrosine phosphatase beta/zeta. The stimulatory effect of aprotinin on pleiotrophin expression and cell migration may explain, at least partly, the problems observed with the clinical use of aprotinin.
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PMID:Aprotinin stimulates angiogenesis and human endothelial cell migration through the growth factor pleiotrophin and its receptor protein tyrosine phosphatase beta/zeta. 1905 95

Increased transforming growth factor-beta (TGF-beta) expression and epidermal growth factor receptor (EGFR) amplification accompany the emergence of highly aggressive human carcinomas. Cooperative signaling between these two growth factor/receptor systems promotes cell migration and synthesis of stromal remodeling factors (i.e., proteases, protease inhibitors) that, in turn, regulate tumor invasion, neo-angiogenesis and inflammation. ranscript profiling of transformed human cells revealed that genes encoding wound healing, matrix remodeling and cell cycle proteins (i.e., the "tissue repair" transcriptome) are significantly up-regulated early after growth factor stimulation. The major inhibitor of plasmin generation, plasminogen activator inhibitor-1 (PAI-1), is among the most highly induced transcripts during the phenotypic transition initiated by TGF-beta maximal expression requires EGFR signaling. PAI-1 induction occurs early in the progression of incipient epidermal squamous cell carcinoma (SCC) and is a significant indicator of poor prognosis in epithelial malignancies. Mouse modeling and molecular genetic analysis of complex systems indicates that PAI-1 regulates the temporal/spatial control of pericellular proteolysis, promotes epithelial plasticity, inhibits capillary regression and facilitates stromal invasion. Defining TGF-beta1-initiated signaling events that cooperate with an activated EGFR to impact the protease-protease inhibitor balance in the tumor microenvironment is critical to the development of novel therapies for the clinical management of human cancers.
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PMID:TGF-beta1-Induced Expression of the Poor Prognosis SERPINE1/PAI-1 Gene Requires EGFR Signaling: A New Target for Anti-EGFR Therapy. 1936 82

The primary aim in cancer therapy is to deliver anti-cancer drugs to their specific molecular targets in the tumour. Here we present a system composed of poly(d,l-lactide-co-glycolide) nanoparticles, cytokeratin specific monoclonal antibody and cystatin, a potent protease inhibitor, that can neutralize the excessive proteolytic activity associated with the invasive and metastatic potential of breast tumour cells. The antibody provides specific targeting of the delivery system to invasive breast epithelial cells and, additionally, prevents the generation of plasmin, a central extracellular protease involved in malignant progression. Polymeric nanoparticles rapidly enter the targeted cells and release the inhibitor cargo within the endosomes/lysosomes. The inhibitor is capable to inactivate lysosomal cysteine proteases, in particular cathepsin B, which is involved in the degradation of extracellular matrix inside the tumour cells. Our approach, which combines nanoparticulate delivery system with the inhibitory potential against extracellular and intracellular proteases, may improve the efficacy of therapy in patients with breast tumours compared to the application of individual protease inhibitors.
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PMID:Inactivation of harmful tumour-associated proteolysis by nanoparticulate system. 1942 96

Hereditary angioedema (HAE) was first described in the 19th century. Over the past 50 years, many details of the pathophysiology and molecular biology of HAE have been elucidated. Two types of HAE, type I and type II, result from mutations in the gene for the broad-spectrum protease inhibitor C1 inhibitor (C1INH). Type I HAE is characterized by low antigenic and functional C1INH levels and type II HAE has normal antigenic but low functional C1INH levels. Type III HAE, by contrast, has normal antigenic and functional C1INH levels. In some families, type III HAE has been linked to mutations in Hageman factor. C1INH is the primary inhibitor of the complement proteases C1r and C1s as well as the contact system proteases activated Hageman factor (coagulation factor XIIa and XIIf) and plasma kallikrein. It is also an inhibitor of plasmin and coagulation factor XIa. The primary mediator of swelling in HAE has now been unequivocally shown to be bradykinin, generated from activation of the plasma contact system. The knowledge gained concerning the underlying mechanisms of the different types of HAE allow the clinician to approach the laboratory diagnosis with confidence and provides opportunities for novel therapeutic strategies.
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PMID:Pathogenesis and laboratory diagnosis of hereditary angioedema. 1984 2


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