Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Follicle-stimulating hormone (FSH) increases the activity of a cell-associated, tissue-type plasminogen activator (tPA) during the initial hours of granulosa cell development. In order to determine the cellular localization of tPA, granulosa cells were labeled with [35S]methionine for 4 h and detergent-solubilized proteins were immunoprecipitated and analyzed by polyacrylamide gel electrophoresis. FSH stimulated the synthesis of a Mr 70,000 PA in granulosa cells that was specifically immunoprecipitated by tPA antibodies. Subcellular fractionation of granulosa cells indicated that the newly biosynthesized tPA was present in a 100,000 X g membrane fraction with minimal tPA in the cytosolic, nuclear, and secreted compartments. Isolation of the extracellular matrix (ECM) synthesized by granulosa cells revealed that the membrane-associated tPA induced by FSH was present in the basement membrane. Deposition of tPA into the ECM increased with time and the enzyme exhibited a low turnover rate of greater than 4 h at this site. The ECM-associated tPA was functionally active as determined by fibrin autography and approximately 95% of the PA activity observed in intact, plated cells was localized to the ECM. When the attachment of cells and deposition of ECM were reduced by maintaining granulosa cells in suspension culture, 40% of the newly synthesized tPA was released instead of being cell-associated. The addition of increasing quantities of anti-tPA IgG or unlabeled tPA minimally depleted the biosynthesized enzyme from the cells, indicating that tPA tightly interacted with the ECM. These results indicate that FSH regulates the biosynthesis of a tPA that is preferentially localized to the ECM region of granulosa cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasminogen activator is associated with the extracellular matrix of ovarian granulosa cells. 313 Nov 66

Both fibrin and tissue macrophages are prominent in the histopathology of chronic inflammatory pulmonary disease. We therefore examined the procoagulant activity of freshly lavaged human alveolar macrophages in vitro. Intact macrophages (5 X 10(5) cells) from 13 healthy volunteers promoted clotting of whole plasma in a mean of 65 s. Macrophage procoagulant activity was at least partially independent of exogenous Factor VII as judged by a mean clotting time of 99 s in Factor VII-deficient plasma and by neutralization of procoagulant activity by an antibody to Factor VII. Immunoprecipitation of extracts of macrophages metabolically labeled with [35S]methionine by Factor VII antibody and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a labeled protein consistent in size with the known molecular weight of blood Factor VII, 48,000. The addition of 50 micrograms of unlabeled, purified Factor VII blocked recovery of the 48,000-mol wt protein. In addition, supernatants of cultured macrophages from six normal volunteers had Factor X-activating activity that was suppressed an average of 71% after culture in the presence of 50 microM coumadin or entirely by the Factor VII antibody indicating that Factor VII synthesized by the cell was biologically active. Endotoxin in vitro induced increases in cellular tissue factor but had no consistent effect on macrophage Factor VII activity. We also examined the tissue factor and Factor VII activities of freshly lavaged alveolar cells from nine subjects with clinical and/or histologic evidence of sarcoidosis. Four of the nine subjects expressed increased tissue factor and seven of nine had increased Factor VII activity over the normal range (P less than 0.01). We estimate the mean Factor VII associated with the cells of sarcoid patients to be 4.7 ng/10(6) cells (range 0.4-20) as compared to a mean of 0.74 ng/10(6) cells (range 0.2-2) for that of normal subjects. Along with previous data showing synthesis of plasminogen activator, these findings indicate that human alveolar macrophages normally synthesize and express measurable amounts of the initial enzymes of proteolytic reactions regulating both fibrin deposition and fibrin resorption. Abnormalities in Factor VII activity in a small group of patients with sarcoidosis raise the possibility that modulation of fibrin turnover by macrophages may contribute to the pathology of this and perhaps other interstitial lung diseases.
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PMID:Human alveolar macrophages synthesize factor VII in vitro. Possible role in interstitial lung disease. 400 51

Porcine tissue-type plasminogen activator (t-PA) increases the binding of 125I-glu-plasminogen to clots made from human plasma or purified fibrinogen in a time and t-PA concentration dependent fashion. The accumulation of plasminogen was faster and greater on noncrosslinked plasma clots than on clots which had been crosslinked by Factor XIIIa. Furthermore, the uptake of plasminogen to crosslinked fibrin clots occurred at a slower rate in the presence of alpha 2-plasmin inhibitor (alpha 2 PI) than in its absence. The kinetics of the uptake of 125I-plasminogen were analyzed using SDS-polyacrylamide gel electrophoresis and radioautography of solubilized plasma clots formed in the presence of t-PA. During the initial phase there was a decrease of clot-bound glu-plasminogen; simultaneously, there was a slight increase in clot-bound glu-plasmin and in plasmin complexed to alpha 2 PI that was crosslinked to alpha-chain polymers of fibrin. This was followed by a marked increase in clot-bound plasminogen having glutamic acid as NH2-terminal (glu-plasminogen) and gluplasmin. t-PA-induced enhancement of glu-plasminogen uptake appears to be mediated by plasmin but does not require the conversion of glu-plasminogen to plasminogen having lysine or methionine as NH2-terminal. The described mechanism assures an adequate supply of clot-bound plasmin, which is the enzyme ultimately involved in the degradation of fibrin.
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PMID:Tissue-type plasminogen activator increases the binding of glu-plasminogen to clots. 621 Mar 7

The secretory glycoproteins synthesized by hepatoma tissue culture (HTC) cells were resolved by two-dimensional polyacrylamide gel electrophoresis of media from cells that were grown in the presence of [(3)H]fucose. These cells synthesize and secrete a complex set of fucose-containing glycoproteins. These secretory glycoproteins are distinct from those glycoproteins present in the plasma membrane of HTC cells. Incubation of HTC cells with dexamethasone has a pronounced effect on the quality and quantity (denoted here as the program) of secretory protein synthesis, as assayed by the short-term incorporation of labeled mannose, fucose, or methionine. The synthesis of two mannose- and fucose- containing glycoprotein series, one of 50,000 mol wt and a more heterogeneous series with mol wt of 35,000-50,000, is increased to a high level by the hormone; conversely, the synthesis of other secretory proteins, particularly one with mol wt of 70,000, is decreased or stopped completely. The synthesis of some major secretory proteins is not affected by the hormone. Dexamethasone has less of an effect on the composition of either total cell membrane glycoprotein or plasma membrane glycoprotein. But there is a decrease in the synthesis of a major membrane glycoprotein series with mol wt of 140,000. These effects of dexamethasone are relatively specific to HTC cells. Neither Reuber H-35 cells nor primary cultures of rat hepatocytes show the same response to the steroid. Two variant HTC cell lines, which were selected for their resistance to dexamethasone inhibition of extracellular plasminogen activator activity, respond only partially to the steroid-induced regulation of the secretory and membrane glycoproteins.
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PMID:Dexamethasone regulates the program of secretory glycoprotein synthesis in hepatoma tissue culture cells. 624 97

Fibrin deposition is prominent in the histopathology of a number of inflammatory lung diseases. Plasmin, activated locally in the lung, can degrade not only this fibrin but potentially structural proteins important to normal lung architecture. Because alveolar macrophages are prominent in inflammatory processes of the lung, we examined the plasminogen activator (PA) activity of human alveolar macrophages. Intact alveolar macrophages from each of 10 healthy subjects expressed PA activity. There was no difference in activity between smoking and nonsmoking individuals. The activator activity was largely cell-associated, but under certain culture conditions, macrophages released a soluble activator into the culture medium. The membrane-bound activator had an apparent molecular mass of 52-55 kD in nonreduced sodium dodecyl sulfate (SDS) gels, and monospecific antibody to urokinase neutralized the enzyme activity. Immunoprecipitation of [35S]methionine-labeled cells showed that human alveolar macrophages actually synthesize the PA in vitro. SDS-gel analysis of the immunoprecipitated material revealed the predominant species of PA to be structurally similar to reduced, active urokinase. We also examined the role of PA in the degradation of both insoluble fibrin and elastin matrices by live macrophages. Cells degraded an insoluble fibrin matrix in the presence of plasminogen whether or not the macrophages contacted the fibrin as long as proteinase inhibitors were not in the culture medium. In the presence of serum proteinase inhibitors, macrophages still degraded a fibrin matrix, but only if they were in contact with the fibrin. Live macrophages also degraded insoluble elastin only when in contact with the elastin but could do so even in the presence of serum proteinase inhibitors. In matrices containing a mixture of fibrin and elastin, cells did not degrade elastin unless plasminogen was added to the medium. These results indicate that normal alveolar macrophages synthesize and express, probably at the cell surface, a PA. The PA is physically and immunochemically similar to urokinase but is membrane bound. The PA is critical to the degradation of fibrin matrices by normal alveolar macrophages. Under tissue conditions where elastin is embedded within other structural proteins, the activator may be rate-limiting in elastin degradation as well. The findings also suggest that live macrophage proteolytic activity is relatively insensitive to the presence of serum proteinase inhibitors, suggesting a mechanism for proteolytic lung injury even in the presence of proteinase-proteinase inhibitor balance in the soluble phase.
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PMID:Degradation of fibrin and elastin by intact human alveolar macrophages in vitro. Characterization of a plasminogen activator and its role in matrix degradation. 636 89

Two-chain 70 000-dalton plasminogen activator of tissue origin displays only weak activity toward plasminogen in a two-component system. The rate of activation is enhanced a minimum of 50-fold by the presence of fibrin clots or denatured proteins. The stimulation must depend on both chemical determinants and spatial configuration, since native proteins, including fibrinogen, lack significant stimulatory activity. These studies employed chemical modifications of four stimulatory proteins (fibrin, denatured fibrinogen, denatured IgG and denatured ovalbumin) to identify a critical role for lysine residues. Arginine, aspartic acid, cysteine, cystine, glutamic acid, histidine, methionine, tyrosine and tryptophan were found not to be essential. The critical spatial determinant(s) remain(s) unknown.
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PMID:A critical role of lysine residues in the stimulation of tissue plasminogen activator by denatured proteins and fibrin clots. 640 38

A new specific and sensitive method for determination of tissue plasminogen activator (t-PA) in plasma samples has been used to demonstrate the presence of a fast inhibitor to t-PA in plasma. By adding [35S]Met internally labeled t-PA (Mr approximately 70,000) to plasma, we were able to demonstrate the rapid formation of a stable complex with an apparent molecular weight of about 115,000 as estimated by gel filtration. The complex was partially purified by immunoadsorbtion chromatography on insolubilized antibodies against porcine t-PA, and a molecular weight of about 120,000 was found by dodecyl sulfate-polyacrylamide gel electrophoresis. From the apparent molecular weight of the complex (120,000) and the molecular weight of t-PA (70,000), a molecular weight of about 50,000 would be expected for the inhibitor. However, gel filtration of inhibitor-rich plasma resulted in the appearance of a symmetrical peak of t-PA inhibitory activity with an apparent molecular weight of about 205,000. The reason for this discrepancy is not known, but several different models are possible.
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PMID:Inactivation of tissue plasminogen activator in plasma. Demonstration of a complex with a new rapid inhibitor. 642 34

A number of macrophage functions were sequentially expressed when the bone marrow precursors of mononuclear phagocytes differentiated in culture in the presence of a specific growth factor, colony-stimulating factor-1. We have defined the expression of apoprotein E (ApoE), a major secreted protein of resident peritoneal macrophages, during maturation of adherent bone marrow-derived mononuclear phagocytes into macrophages. By 5 d the bone marrow macrophages were active secretory cells, but few cells contained intracellular immunoreactive ApoE, and little, if any, ApoE was secreted. ApoE secretion was initiated at 9 d, and this correlated with an increase in the percentage of macrophages containing intracellular ApoE. The onset of ApoE secretion was selective, and little change occurred in the other major secreted proteins detected by [35S]methionine incorporation. In parallel, the high rate of plasminogen activator secretion, which peaked at 7 d, decreased markedly. ApoE secretion was not associated with altered expression of the macrophage surface antigen, Ia, or with secretion of fibronectin. Virtually all cells in independent colonies of bone marrow-derived macrophages eventually expressed ApoE. The proliferating monocyte/macrophage-like cell lines P388D1, J774.2, WEHI-3, RAW 264.1, and MGI.D+ secreted little or no ApoE. These data establish that ApoE secretion is developmentally regulated.
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PMID:Onset of apoprotein E secretion during differentiation of mouse bone marrow-derived mononuclear phagocytes. 660 29

A plasminogen activator, previously designated as rat urinary esterase A (Nustad, K., and Pierce, J. V. (1974) Biochemistry 13, 2312-2319), was separated from kallikrein of rat urine and purified to homogeneity. In polyacrylamide slab gel electrophoresis, the purified enzyme showed three closely migrating protein bands which were labeled with [14C]diisopropylphosphorofluoridate and stained on a zymogram using the chromogenic substrate methionine-alpha-naphthyl ester. Two chains, heavy chain(s) (Mr approximately 15,800, 14,200) and light chain(s) (Mr approximately 8,850, 8,550), were separated in SDS-polyacrylamide gel under reducing conditions, while two bands (Mr approximately 24,500 and 23,000) were seen under nonreducing conditions. The active site of the enzyme was associated with the heavy chain. The purified enzyme was stained for carbohydrate by the periodic acid-Schiff reagent. Five bands were distinguished in slab gel electrofocusing with isoelectric points ranging from 5.05 to 5.45. The purified enzyme lysed fibrin clots containing plasminogen but not plasminogen-free fibrin. It hydrolyzed benzyloxylcarbonyl-Gly-Gly-Arg-amino-4-trifluoromethyl coumarin, and a Km of 53 microM and a Vmax of 63 mumol/min/mg of enzyme were obtained at pH 8.0 and 37 degrees C. The enzyme cleaved kininogen substrates to produce kinin which was measured by bioassay or radioimmunoassay. The enzyme was inhibited by soybean or lima bean trypsin inhibitor, aprotinin, alpha 1-antitrypsin, phenylmethanesulfonyl fluoride, D-Phe-Phe-ArgCH2Cl, antipain, leupeptin, benzamidine, and pentamidine. Its pH optimum was 8.5 to 9.0; it was unstable on dilution and on heating. On immunoelectrophoresis, an antiserum to the esterase formed precipitin arcs with rat plasma and this enzyme at identical positions, which in turn were different from those formed with kallikrein. This urinary enzyme belongs to the family of serine proteinases and is immunologically related to urinary kallikrein.
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PMID:Purification and characterization of rat urinary esterase A, a plasminogen activator. 668 2

The present studies examined the biochemical characteristics which were carried on from parent cells during fusion of human skin fibroblasts (HSF) with spleen cells of BALB/c mice preimmunized with hormone-responsive and nonresponsive human malignant melanoma cells (HMMC-ShA and HMMC-SR). The melanoma cells used as immunogens were either unmodified or preincubated with vibrio cholera neuraminidase (VCN), with estradiol (E), or with progesterone (P). Responsiveness was monitored by (3H) thymidine and (35S) methionine incorporation. Responsiveness to estradiol, concanavalin A (Con A) and to phytoheamagglutinin (PHA) were carried out, whereas malignancy was suppressed extensively in the cloned hybrids. On the immunizing tumor cells, VCN treatment enhanced (3H) thymidine but reduced (35S)-methionine incorporation and malignancy of the estradiol responsive melanoma cells (HMMC-ShA). VCN treatment enhanced (3H)-thymidine incorporation, but had no effect on (35S)-methionine incorporation and malignancy of the estradiol nonresponsive HMMC-SR cells. Estradiol treatment enhanced plasminogen activator (PA) activity and malignancy, whereas progesterone treatment reduced (inhibited) plasminogen activator activity and suppressed malignancy of the immunizing tumor cells. The PA from estradiol-responsive and from nonresponsive melanoma cells differed in their electrophoretic mobility on polyacrylamide gel electrophoresis.
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PMID:Correlation between plasminogen activator activity of immunizing tumor cells and complement-mediated cytotoxic antibodies secreted by cloned hybrid cells. 719 36


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