Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The study of the interaction between activated protein C (APC) and non-plasmatic inhibitors allowed us to demonstrate that aprotinin is a potent competitive inhibitor of APC with a Ki of 1.35 mumol/L. It was possible to adsorb immunopurified protein C (PC) activated by venom activator to insolubilized aprotinin and to recover the active enzyme after elution by HCl 0.1 N or by a chaotropic ion, for example KSCN 3 mol/L. The interaction involved the active-site of the enzyme since PC and DIP-APC did not bind to the matrix. Thus, APC could be purified, after activation, in a one-stage procedure out of a mixture of protein such as a prothrombin complex concentrate.
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PMID:Inhibition of activated protein C by aprotinin and the use of the insolubilized inhibitor for its purification. 169 90

Thrombomodulin is an endothelial cell surface receptor for thrombin that acts as a physiological anticoagulant. The properties of recombinant human thrombomodulin were studied in COS-7, CHO, CV-1, and K562 cell lines. Thrombomodulin was expressed on the cell surface as shown by the acquisition of thrombin-dependent protein C activation. Like native thrombomodulin, recombinant thrombomodulin contained N-linked oligosaccharides, had Mr approximately 100,000, and was inhibited or immunoprecipitated by anti-thrombomodulin antibodies. Binding studies demonstrated that nonrecombinant thrombomodulin expressed by A549 carcinoma cells and recombinant thrombomodulin expressed by CV-1 and K562 cells had similar Kd's for thrombin of 1.3 nM, 3.3 nM, and 4.7 nM, respectively. The Kd for DIP-thrombin binding to recombinant thrombomodulin on CV-1(18A) cells was identical with that of thrombin. Increasing concentrations of hirudin or fibrinogen progressively inhibited the binding of 125I-DIP-thrombin, while factor Va did not inhibit binding. Three synthetic peptides were tested for ability to inhibit DIP-thrombin binding. Both the hirudin peptide Hir53-64 and the thrombomodulin fifth-EGF-domain peptide Tm426-444 displaced DIP-thrombin from thrombomodulin, but the factor V peptide FacV30-43 which is similar in composition and charge to Hir53-64 showed no binding inhibition. The data exclude the significant formation of a ternary complex consisting of thrombin, thrombomodulin, and hirudin. These studies are consistent with a model in which thrombomodulin, hirudin, and fibrinogen compete for binding to DIP-thrombin at the same site.
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PMID:Equilibrium binding of thrombin to recombinant human thrombomodulin: effect of hirudin, fibrinogen, factor Va, and peptide analogues. 217 73

Lysis of clots prepared from native or citrated whole blood as measured by release of 125I fibrinogen degradation products was 10% or less at 20 hours. Lysis of these clots was accelerated by activated protein C in a dose-dependent manner (0.1 to 20 micrograms/ml) from less than 10% to 60-80% at 20 hours. Lysis of clots prepared from native or citrated platelet poor plasma across the same concentration range of activated protein C was less than 15%. Gla-domain-less activated protein C was equally effective in accelerating clot lysis whereas DIP-activated protein C or factor Xa did not accelerate clot lysis. This suggested that this action of activated protein C was enzymatic and this this action was limited to protein C among the vitamin K dependent proteins. The unresponsiveness of platelet poor plasma to activated protein C was completely restored to that of whole blood by addition of mononuclear leukocytes. Addition of red corpuscles or platelets alone had no effect on this response, while addition of polymorphonuclear leukocytes partially restored this response. Addition of metabolic inhibitors 2-deoxyglucose and oligomycin inhibited the response of whole blood and of plasma-mononuclear leukocytes to activated protein C. Reconstitution studies of platelet poor plasma made deficient in plasminogen activator and plasminogen showed that accelerated clot lysis produced by mononuclear leukocytes and activated protein C required the presence of plasminogen. We concluded, therefore, that activated protein C accelerates whole blood or plasma-leukocyte clot lysis by modulating activation of the plasminogen system by metabolically active leukocytes.
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PMID:Whole blood clot lysis: in vitro modulation by activated protein C. 383 29

Mononuclear leukocytes release an inhibitor of plasminogen activators. Mononuclear leukocyte mixtures (400 to 1,000/mm3) lysed fibrin (8.3 microM) clots in the presence of plasminogen (0.58 microM). Anti-urokinase IgG (0.16 microM) inhibited this fibrinolysis. 2-Deoxyglucose (5 mM) and oligomycin (2.3 microM) also inhibited fibrinolysis. Incubation of mononuclear leukocytes (3,200/microliter) with phorbol-12 myristate 13-acetate (20 nM) for ten minutes at 37 degrees C aggregated the monocyte and platelet components and inhibited fibrinolysis. The releasate from these stimulated cells in dilutions ranging from undiluted to 1:16 inhibited urokinase (1.6 pM) and tissue plasminogen activator (1.4 pM). This releasate did not inhibit plasmin (2.5 nM). Incubation of this releasate with activated protein C (33 nM to 333 nM) for ten minutes at 37 degrees C before addition of either urokinase, or tissue plasminogen activator and plasminogen completely prevented this inhibition. Thrombin, factor Xa, DIP-activated protein C had no affect on this inhibition. We conclude that activated protein C facilitates fibrinolysis by preventing inhibition of plasminogen activators. This may be a mechanism by which activated protein C increases fibrinolytic activity in vivo.
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PMID:A new function for activated protein C: activated protein C prevents inhibition of plasminogen activators by releasate from mononuclear leukocytes--platelet suspensions stimulated by phorbol diester. 392 Jul 76

We investigated the effect of activated protein C (APC) on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats to investigate the possible usefulness of APC as a treatment for adult respiratory distress syndrome. Intravenously administered LPS (5 mg/kg) significantly increased pulmonary vascular permeability. APC prevented the LPS-induced increase in pulmonary vascular permeability observed at 6 hours. Heparin plus antithrombin III (ATIII) and active site-blocked factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, inhibited LPS-induced coagulopathy but did not prevent LPS-induced pulmonary vascular injury. LPS-induced pulmonary vascular injury was significantly attenuated in rats with nitrogen mustard-induced leukocytopenia and in rats treated with ONO-5046, a potent granulocyte elastase inhibitor. Administration of LPS also increased pulmonary accumulation of leukocytes, as evaluated by measurement of myeloperoxidase activity in the lungs. APC significantly reduced LPS-induced increases in pulmonary accumulation of leukocytes at 1 hour. Neither ATIII plus heparin nor DEGR-Xa inhibited leukocyte accumulation. Active site-blocked APC (DIP-APC) prevented neither the LPS-induced pulmonary accumulation of leukocytes nor the LPS-induced increase in pulmonary vascular permeability. These results suggest that the mechanism of APC inhibition of LPS-induced pulmonary vascular injury was independent of its anticoagulant activity and was related to its ability to inhibit accumulation of leukocytes. In addition, these findings suggest that the serine protease activity of APC may be essential to its inhibitory effect on LPS-induced pulmonary accumulation of leukocytes and subsequent pulmonary vascular injury.
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PMID:Activated protein C attenuates endotoxin-induced pulmonary vascular injury by inhibiting activated leukocytes in rats. 855 86

We investigated the effect of activated protein C (APC) on pulmonary vascular injury and the increase in tumor necrosis factor (TNF) levels in lipopolysaccharide (LPS)-treated rats to determine whether APC reduces LPS-induced endothelial damage by inhibiting cytokine production. Intravenously administered LPS (5 mg/kg) induced pulmonary vascular injury, as indicated by an increase in the lung wet-to-dry weight ratio. LPS-induced pulmonary vascular injury was prevented by APC but not by active site-blocked factor Xa [dansyl glutamyl-glycyl-arginyl chloromethyl detone-treated activated factor X (DEGR-Xa)], a selective inhibitor of thrombin generation, or inactivated APC [diisopropyl fluorophosphate-treated APC (DIP-APC)]. APC, but not DEGR-Xa or DIP-APC, significantly inhibited the LPS-induced increase in the plasma level of TNF. APC significantly inhibited the production of TNF by LPS-stimulated monocytes in a dose-dependent fashion in vitro, but DIP-APC did not. APC did not inhibit the functions of activated neutrophils in vitro. These findings suggest that APC prevented LPS-induced pulmonary vascular injury by inhibiting TNF production by monocytes and not via its anticoagulant activity. The serine protease activity of APC appears to be essential for inhibition of TNF production.
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PMID:Activated protein C prevents LPS-induced pulmonary vascular injury by inhibiting cytokine production. 912 69

Activated protein C (APC), an important inhibitor of the coagulation system, has recently been shown to prevent tissue injury by blocking the activation of leukocytes. To determine whether APC can also prevent post-traumatic spinal cord injury (SCI), a condition in which leukocytes play an important role, we tested the effects of APC on SCI induced in rats by compression trauma. Administration of APC, either before or after the induction of SCI, markedly reduced the motor disturbances in these animals. In contrast, neither an inactive derivative of activated factor X (DEGR-Xa), a selective inhibitor of thrombin generation, nor active site-blocked APC (DIP-APC) reduced the motor disturbances. Histological examination revealed that intramedullary hemorrhages, observed 24 hr after trauma, were significantly reduced in the animals administered APC. The increase in the tissue level of tumor necrosis factor-alpha (TNF-alpha) and the accumulation of neutrophils in the damaged segment of the spinal cord were significantly inhibited in the animals that had received APC, but these were not inhibited in those administered DIP-APC or DEGR-Xa. The induction of leukocytopenia had the same effect as APC, in that it significantly reduced motor disturbances, tissue levels of TNF-alpha, and neutrophil accumulation in the animals subjected to compressive SCI. These findings suggest that in SCI, APC reduces motor disturbances primarily by reducing the amount of TNF-alpha at the site of injury, thus inhibiting neutrophil accumulation and the resultant damage to the endothelial cells.
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PMID:Activated protein C reduces the severity of compression-induced spinal cord injury in rats by inhibiting activation of leukocytes. 2165 74

We examined whether activated protein C (APC) reduces ischemia/reperfusion (I/R)-induced renal injury by inhibiting leukocyte activation. In a rat model, intravenous administration of APC markedly reduced I/R-induced renal dysfunction and histological changes, whereas intravenous administration of dansyl glutamylglycylarginyl chloromethyl ketone-treated factor Xa (DEGR-FXa; active-site-blocked factor Xa), heparin or diisopropyl fluorophosphate-treated APC (DIP-APC; inactive derivative of ARC) had no effect. Furthermore, APC significantly inhibited the I/R-induced decrease in renal tissue blood flow and the increase in the vascular permeability, whereas neither DEGR-FXa, heparin, nor DIP-APC produced such effects. Renal I/R-induced increases in plasma levels of fibrin degradation products were significantly inhibited by APC, DEGR-FXa, and heparin. These observations suggest that APC reduces I/R-induced renal injury independently of its anticoagulant effects but in a manner dependent on its serine protease activity. Renal levels of tumor necrosis factor-alpha (TNF-alpha), rat interleukin-8, and myeloperoxidase were significantly increased after renal I/R. These increases were significantly inhibited by APC but not by DEGR-FXa, heparin, or DIP-APC. Leukocytopenia produced effects similar to those of APC. These findings strongly suggest that APC protects against I/R-induced renal injury not by inhibiting coagulation abnormalities but by inhibiting activation of leukocytes that play an important role in I/R-induced renal injury. Inhibition of leukocyte activation by APC could be explained by the inhibitory activity of TNF-alpha. (Blood. 2000;95:3781-3787)
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PMID:Activated protein C reduces ischemia/reperfusion-induced renal injury in rats by inhibiting leukocyte activation. 2354 58

Activated protein C (APC), a natural anticoagulant, has recently been demonstrated to activate the mitogen-activated protein kinase (MAPK) pathway in endothelial cells in vitro. Because the MAPK pathway is implicated in endothelial cell proliferation, it is possible that APC induces endothelial cell proliferation, thereby causing angiogenesis. We examined this possibility in the present study. APC activated the MAPK pathway, increased DNA synthesis, and induced proliferation in cultured human umbilical vein endothelial cells dependent on its serine protease activity. Antibody against the endothelial protein C receptor (EPCR) inhibited these events. Early activation of the MAPK pathway was inhibited by an antibody against protease-activated receptor-1, whereas neither late and complete activation of the MAPK pathway nor endothelial cell proliferation were inhibited by this antibody. APC activated endothelial nitric oxide synthase (eNOS) via phosphatidylinositol 3-kinase-dependent phosphorylation, followed by activation of protein kinase G, suggesting that APC bound to EPCR might activate the endothelial MAPK pathway by a mechanism similar to that of VEGF. APC induced morphogenetic changes resembling tube-like structures of endothelial cells, whereas DIP-APC did not. When applied topically to the mouse cornea, APC clearly induced angiogenesis in wild-type mice, but not in eNOS knockout mice. These in vitro events induced by APC might at least partly explain the angiogenic activity in vivo. This angiogenic activity of APC might contribute to maintain proper microcirculation in addition to its antithrombotic activity.
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PMID:Activated protein C induces endothelial cell proliferation by mitogen-activated protein kinase activation in vitro and angiogenesis in vivo. 1516 95

The impact of smoking on male fertility has been extensively acknowledged. Many studies have shown that smoking reduces sperm production, motility and fertilizing capacity by increasing seminal oxidative stress and DNA damage. In this study, expression profiles of miRNAs and their predicted target genes, showing dysregulation in smokers and associated with male infertility, were obtained, using Gene Expression Omnibus (GEO) datasets. Differentially expressed miRNAs, related to male infertility in sperm samples of smoking and non-smoking men, were picked out using the GEO2R online tool. Then, the target genes of each selected miRNA were predicted by using MiR-DIP. The target genes lists were compared to differentially expressed genes from the smoking and infertile men datasets. Common genes were chosen for further enrichment analysis such as GO, KEGG and PPI network analysis via STRING and MCODE. Then, four miRNAs (miR-26a, miR-32, miR-188-3p and miR-512-3p) which had shown differential expression in male infertility in other studies, and also had differential expression in smoking men compared to non-smokers, were screened out. Moreover, a module consisting of eight genes was identified as hub genes, including APC, NIPBL, ARID4B, TNRC6A, GIGYF2, ELAVL1, RHOF and SRSF1. These were highly correlated with male infertility and impairment of spermatogenesis. This study provides a comprehensive bioinformatics analysis of miRNAs and their target genes affecting male infertility in smokers. The results showed a collection of the most relevant genes and effective molecular pathways, which may serve as potential markers for the early detection of spermatogenesis disorders leading to infertility in smokers, after experimental validation.
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PMID:Identification of miRNAs and the target genes related to male infertility and smoking using bioinformatics approaches. 3261 69


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