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Plasmin
Terms modified by Plasmin Selected AbstractsTissue-type plasminogen activator-plasmin-BDNF modulate glutamate-induced phase-shifts of the mouse suprachiasmatic circadian clock in vitroEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2009Xiang Mou Abstract The mammalian circadian clock in the suprachiasmatic nucleus (SCN) maintains environmental synchrony through light signals transmitted by glutamate released from retinal ganglion terminals. Brain-derived neurotrophic factor (BDNF) is required for light/glutamate to reset the clock. In the hippocampus, BDNF is activated by the extracellular protease, plasmin, which is produced from plasminogen by tissue-type plasminogen activator (tPA). We provide data showing expression of proteins from the plasminogen activation cascade in the SCN and their involvement in circadian clock phase-resetting. Early night glutamate application to SCN-containing brain slices resets the circadian clock. Plasminogen activator inhibitor-1 (PAI-1) blocked these shifts in slices from wild-type mice but not mice lacking its stabilizing protein, vitronectin (VN). Plasmin, but not plasminogen, prevented inhibition by PAI-1. Both plasmin and active BDNF reversed ,2 -antiplasmin inhibition of glutamate-induced shifts. ,2 -Antiplasmin decreased the conversion of inactive to active BDNF in the SCN. Finally, both tPA and BDNF allowed daytime glutamate-induced phase-resetting. Together, these data are the first to demonstrate expression of these proteases in the SCN, their involvement in modulating photic phase-shifts, and their activation of BDNF in the SCN, a potential ,gating' mechanism for photic phase-resetting. These data also demonstrate a functional interaction between PAI-1 and VN in adult brain. Given the usual association of these proteins with the extracellular matrix, these data suggest new lines of investigation into the locations and processes modulating mammalian circadian clock phase-resetting. [source] Safety of plasmin in the setting of concomitant aspirin and heparin administration in an animal model of bleedingJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 12 2003S. Sadeghi Summary., Plasmin is a direct thrombolytic which has been shown to have a strikingly favorable benefit to risk profile in comparison with plasminogen activators, notably tissue plasminogen activator (t-PA). As heparin is known to increase the risk of hemorrhage when co-administered with a plasminogen activator, we asked whether adjunct antithrombotic agents such as aspirin and heparin would affect the safety of plasmin. Three groups of rabbits were administered plasmin at a dose (4 mg kg,1) designed to induce significant decreases in antiplasmin, fibrinogen and factor (F)VIII, to about 25, 40 and 40%, respectively, of baseline values, but not cause prolongation of the ear puncture bleeding time. In a blinded and randomized trial, the results show that an intravenous aspirin bolus plus heparin administered as a bolus followed by a maintenance continuous infusion did not significantly prolong the bleeding time during plasmin infusion. These data indicate that in the rabbit, concomitant use of aspirin plus heparin does not affect the safety of a therapeutic dose of plasmin. [source] Systemic levels of plasmin,antiplasmin complexes are correlated with the expansion rate of small abdominal aortic aneurysmsBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2001J. S. Lindholt Background: The cystatine proteolytic system, the serine proteolytic system and the metallodependent proteolytic system have all been reported to be involved in the matrix degradation of the aortic wall, causing abdominal aortic aneurysm (AAA). Plasmin is a common activator of all three systems and could theoretically be involved in the pathogenesis of AAA by activating all three systems. However, plasmin is immediately inactivated by antiplasmin, forming plasmin,antiplasmin (PAP) complexes when it reaches the circulation. This study was designed to assess whether the systemic levels of PAP complex in conservatively treated patients with AAA could be related to the natural history of AAA. Methods: In 1994, 112 of 141 men with AAA (greater than 3 cm) diagnosed by population screening were interviewed, examined, and had blood samples taken and prepared for serum and ethylenediamine tetra-acetic acid plasma by a standard method. The serum and plasma were frozen at , 21°C until analysis. Of the 112 patients, 99 were followed with annual control scans and blood pressure measurements for 1,5 (mean 2·5) years, and were referred for operation if the AAA exceeded 5 cm in diameter. Of the 99 patients, a random sample of 70 had their level of PAP complexes determined (Dade Behring, Rødovre, Denmark). Furthermore, the level of serum elastin peptides (SEPs) was determined by enzyme-linked immunosorbent assay. Spearman's rank sum correlation test, multivariate linear regression analysis and receiver,operator characteristic (ROC) curve analysis were used for statistical analysis (SPSS 10.0; SPSS, Chicago, Illinois, USA). Results: The level of PAP complex was positively correlated with annual expansion rate (r = 0·29, P = 0·01), but not with the initial AAA size (r = 0·17, P = 0·16) or SEP (r = 0·04, P = 0·77). The significant association to expansion persisted after adjustment for initial AAA size, SEP and smoking. Furthermore, the level of PAP complex was significantly predictive for AAAs expanding to operation recommendable size (area under ROC curve 65 per cent), with an optimal sensitivity and specificity of 65 and 67 per cent respectively. SEP level was also significantly predictive for AAAs expanding to operation recommendable size (area under ROC curve 56 per cent), with an optimal sensitivity and specificity of 56 and 57 per cent. Conclusion: The progression of AAA seems to be caused by a general activation of the proteolytic systems involving plasmin and not by genetic or environmental factors causing increased activation of specific proteases or decreased activity of their specific inhibitors. Furthermore, the level of PAP complex in patients with an aneurysm seems to have a better and independently predictive value of the natural history of AAA, compared with the best serological predictor known to date, the serum level of elastin peptides. © 2001 British Journal of Surgery Society Ltd [source] Synthesis of Benzylamides of Dipeptides as Potential Inhibitors of Plasmin.CHEMINFORM, Issue 6 2004K. Midura-Nowaczek No abstract is available for this article. [source] Efficient copackaging and cotransport yields postsynaptic colocalization of neuromodulators associated with synaptic plasticityDEVELOPMENTAL NEUROBIOLOGY, Issue 10 2008J.E. Lochner Abstract Recent data suggest that tissue plasminogen activator (tPA) influences long-term plasticity at hippocampal synapses by converting plasminogen into plasmin, which then generates mature brain-derived neurotrophic factor (mBDNF) from its precursor, proBDNF. Motivated by this hypothesis, we used fluorescent chimeras, expressed in hippocampal neurons, to elucidate (1) mechanisms underlying plasminogen secretion from hippocampal neurons, (2) if tPA, plasminogen, and proBDNF are copackaged and cotransported in hippocampal neurons, especially within dendritic spines, and (3) mechanisms mediating the transport of these neuromodulators to sites of release. We find that plasminogen chimeras traffic through the regulated secretory pathway of hippocampal neurons in dense-core granules (DCGs) and that tPA, plasminogen, and proBDNF chimeras are extensively copackaged in DCGs throughout hippocampal neurons. We also find that 80% of spines that contain DCGs contain chimeras of these neuromodulators in the same DCG. Finally, we demonstrate, for the first time, that neuromodulators undergo cotransport along dendrites in rapidly mobile DCGs, indicating that neuromodulators can be efficiently recruited into active spines. These results support the hypothesis that tPA mediates synaptic activation of BDNF by demonstrating that tPA, plasminogen, and proBDNF colocalize in DCGs in spines, where these neuromodulators can undergo activity-dependent release and then interact and/or mediate changes that influence synaptic efficacy. The results also raise the possibility that frequency-dependent changes in extents of neuromodulator release from DCGs influence the direction of plasticity at hippocampal synapses by altering the relative proportions of two proteins, mBDNF and proBDNF, that exert opposing effects on synaptic efficacy. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008. [source] Functional approach to investigate Lp(a) in ischaemic heart and cerebral diseasesEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2 2003A. De La Peña-Díaz Abstract Background Lp(a), a major cardiovascular risk factor, contains a specific apolipoprotein, apo(a), which by virtue of structural homology with plasminogen inhibits the formation of plasmin, the fibrinolytic enzyme. A number of clinical reports support the role of Lp(a) as a cardiovascular or cerebral risk factor, and experimental data suggest that it may contribute to atherothrombosis by inhibiting fibrinolysis. Design A well-characterized model of a fibrin surface and an apo(a)-specific monoclonal antibody were used to develop a functional approach to detect pathogenic Lp(a). The assay is based on the competitive binding of Lp(a) and plasminogen for fibrin, and quantifies fibrin-bound Lp(a). High Lp(a) binding to fibrin is correlated with decreased plasmin formation. In a transversal case,control study we studied 248 individuals: 105 had a history of ischaemic cardiopathy (IC), 52 had cerebro-vascular disease (CVD) of thrombotic origin, and 91 were controls. Results The remarkably high apo(a) fibrin-binding in CVD (0·268 ± 0·15 nmol L,1) compared with IC (0·155 ± 0·12 nmol L,1) suggests the existence of peculiar and poorly understood differences in pro- or anti-thrombotic mechanisms in either cerebral and/or coronary arteries. Conclusions Our results demonstrated that Lp(a) fibrin-binding and small Apo(a) isoforms are associated with athero-thrombotic disease. [source] Interferon-, in healthy subjects: selective modulation of inflammatory mediatorsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 6 2001J. De Metz Background It is suggested that interferon-, (IFN-,), like other cytokines, is a mediator in the host inflammatory response, which could be of importance in the pathophysiology of sepsis. The role of IFN-, in human host inflammatory responses, however, has not been studied. Design In a placebo-controlled trial we studied the acute effects of IFN-, administration on host inflammatory mediators in healthy men: i.e. the cytokine/chemokine cascade system, acute-phase proteins, activation markers of the innate cellular immunity and coagulation/fibrinolysis parameters. Results IFN-, increased plasma levels of interleukin-6 (IL-6), IL-8 and IFN-,-inducible protein-10 (IP-10) (P < 0·05), but did not affect plasma levels of other cytokines (IL-4, IL-10, tumour necrosis factor-,, IL-12p40/p70). Plasma concentrations of C-reactive protein and secretory phospholipase A2 both increased (P < 0·05). Plasma levels of the leucocyte activation marker elastase-,1,antitrypsin complexes increased after IFN-, administration (P < 0·05), IFN-, increased the percentage of high-affinity Fc,-receptor (Fc,RI) -positive neutrophils (P < 0·05), but did not affect the mean fluorescence intensity of Fc,RI on neutrophils. Procoagulant and profibrinolytic effects of IFN-, were evidenced by increased plasma levels of prothrombin fragment F1 + F2, tissue-plasminogen activator and plasmin-,2,antiplasmin complexes (P < 0·05). Conclusion We conclude that IFN-, selectively affects host inflammatory mediators in humans. [source] Tissue-type plasminogen activator-plasmin-BDNF modulate glutamate-induced phase-shifts of the mouse suprachiasmatic circadian clock in vitroEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2009Xiang Mou Abstract The mammalian circadian clock in the suprachiasmatic nucleus (SCN) maintains environmental synchrony through light signals transmitted by glutamate released from retinal ganglion terminals. Brain-derived neurotrophic factor (BDNF) is required for light/glutamate to reset the clock. In the hippocampus, BDNF is activated by the extracellular protease, plasmin, which is produced from plasminogen by tissue-type plasminogen activator (tPA). We provide data showing expression of proteins from the plasminogen activation cascade in the SCN and their involvement in circadian clock phase-resetting. Early night glutamate application to SCN-containing brain slices resets the circadian clock. Plasminogen activator inhibitor-1 (PAI-1) blocked these shifts in slices from wild-type mice but not mice lacking its stabilizing protein, vitronectin (VN). Plasmin, but not plasminogen, prevented inhibition by PAI-1. Both plasmin and active BDNF reversed ,2 -antiplasmin inhibition of glutamate-induced shifts. ,2 -Antiplasmin decreased the conversion of inactive to active BDNF in the SCN. Finally, both tPA and BDNF allowed daytime glutamate-induced phase-resetting. Together, these data are the first to demonstrate expression of these proteases in the SCN, their involvement in modulating photic phase-shifts, and their activation of BDNF in the SCN, a potential ,gating' mechanism for photic phase-resetting. These data also demonstrate a functional interaction between PAI-1 and VN in adult brain. Given the usual association of these proteins with the extracellular matrix, these data suggest new lines of investigation into the locations and processes modulating mammalian circadian clock phase-resetting. [source] Inhibition of urokinase receptor gene expression and cell invasion by anti-uPAR DNAzymes in osteosarcoma cellsFEBS JOURNAL, Issue 14 2005Charles E. De Bock The urokinase-type plasminogen activator (uPA) receptor (uPAR) has been implicated in signal transduction and biological processes including cancer metastasis, angiogenesis, cell migration, and wound healing. It is a specific cell surface receptor for its ligand uPA, which catalyzes the formation of plasmin from plasminogen, thereby activating the proteolytic cascade that contributes to the breakdown of extracellular matrix, a key step in cancer metastasis. We have synthesized three different DNA enzymes (Dz372, Dz483 and Dz720) targeting uPAR mRNA at three separate purine (A or G),pyrimidine (U or C) junctions. Two of these DNAzymes, Dz483 and Dz720, cleaved uPAR transcript in vitro with high efficacy and specificity at a molar ratio (uPAR to Dz) as low as 1 : 0.2. When analyzed over 2 h with a 200-fold molar excess of DNAzymes to uPAR transcript, Dz720 and Dz483 were able to decrease uPAR transcript in vitro by ,,93% and ,,84%, respectively. They also showed an ability to cleave uPAR mRNA in the human osteosarcoma cell line Saos-2 after transfection. The DNAzyme Dz720 decreased uPAR mRNA within 4 h of transfection, and inhibited uPAR protein concentrations by 55% in Saos-2 cells. The decrease in uPAR mRNA and protein concentrations caused by Dz720 significantly suppressed Saos-2 cell invasion as assessed by an in vitro Matrigel assay. The use of DNAzyme methodology adds a new potential clinical agent for decreasing uPAR mRNA expression and inhibiting cancer invasion and metastasis. [source] Nonlysine-analog plasminogen modulators promote autoproteolytic generation of plasmin(ogen) fragments with angiostatin-like activityFEBS JOURNAL, Issue 4 2004Shigeki Ohyama We recently discovered several nonlysine-analog conformational modulators for plasminogen. These include SMTP-6, thioplabin B and complestatin that are low molecular mass compounds of microbial origin. Unlike lysine-analog modulators, which increase plasminogen activation but inhibit its binding to fibrin, the nonlysine-analog modulators enhance both activation and fibrin binding of plasminogen. Here we show that some nonlysine-analog modulators promote autoproteolytic generation of plasmin(ogen) derivatives with its catalytic domain undergoing extensive fragmentation (PMDs), which have angiostatin-like anti-endothelial activity. The enhancement of urokinase-catalyzed plasminogen activation by SMTP-6 was followed by rapid inactivation of plasmin due to its degradation mainly in the catalytic domain, yielding PMD with a molecular mass ranging from 68 to 77 kDa. PMD generation was observed when plasmin alone was treated with SMTP-6 and was inhibited by the plasmin inhibitor aprotinin, indicating an autoproteolytic mechanism in PMD generation. Thioplabin B and complestatin, two other nonlysine-analog modulators, were also active in producing similar PMDs, whereas the lysine analog 6-aminohexanoic acid was inactive while it enhanced plasminogen activation. Peptide sequencing and mass spectrometric analyses suggested that plasmin fragmentation was due to cleavage at Lys615-Val616, Lys651-Leu652, Lys661-Val662, Lys698-Glu699, Lys708-Val709 and several other sites mostly in the catalytic domain. PMD was inhibitory to proliferation, migration and tube formation of endothelial cells at concentrations of 0.3,10 µg·mL,1. These results suggest a possible application of nonlysine-analog modulators in the treatment of cancer through the enhancement of endogenous plasmin(ogen) fragment formation. [source] Identification of amino acids in antiplasmin involved in its noncovalent ,lysine-binding-site'-dependent interaction with plasminFEBS JOURNAL, Issue 9 2003Haiyao Wang The lysine-binding-site-mediated interaction between plasmin and antiplasmin is of great importance for the fast rate of this reaction. It also plays an important part in regulating the fibrinolytic enzyme system. To identify structures important for its noncovalent interaction with plasmin, we constructed seven single-site mutants of antiplasmin by modifying charged amino acids in the C-terminal part of the molecule. All the variants were expressed in the Drosophila S2 cell system, purified, and shown to form stable complexes with plasmin. A kinetic evaluation revealed that two mutants of the C-terminal lysine (K452E or K452T) did not differ significantly from wild-type antiplasmin in their reactions with plasmin, in either the presence or absence of 6-aminohexanoic acid, suggesting that this C-terminal lysine is not important for this reaction. On the other hand, modification of Lys436 to Glu decreased the reaction rate about fivefold compared with wild-type. In addition, in the presence of 6-aminohexanoic acid, only a small decrease in the reaction rate was observed, suggesting that Lys436 is important for the lysine-binding-site-mediated interaction between plasmin and antiplasmin. Results from computerized molecular modelling of the C-terminal 40 amino acids support our experimental data. [source] Crystal structure of a staphylokinase variantFEBS JOURNAL, Issue 2 2002A model for reduced antigenicity Staphylokinase (SAK) is a 15.5-kDa protein from Staphylococcus aureus that activates plasminogen by forming a 1 : 1 complex with plasmin. Recombinant SAK has been shown in clinical trials to induce fibrin-specific clot lysis in patients with acute myocardial infarction. However, SAK elicits high titers of neutralizing antibodies. Biochemical and protein engineering studies have demonstrated the feasibility of generating SAK variants with reduced antigenicity yet intact thrombolytic potency. Here, we present X-ray crystallographic evidence that the SAK(S41G) mutant may assume a dimeric structure. This dimer model, at 2.3-Å resolution, could explain a major antigenic epitope (residues A72,F76 and residues K135-K136) located in the vicinity of the dimer interface as identified by phage-display. These results suggest that SAK antigenicity may be reduced by eliminating dimer formation. We propose several potential mutation sites at the dimer interface that may further reduce the antigenicity of SAK. [source] Zymogen activation in the streptokinase,plasminogen complexFEBS JOURNAL, Issue 13 2000Ile1 is required for the formation of a functional active site Plasminogen (Plgn) is usually activated by proteolysis of the Arg561,Val562 bond. The amino group of Val562 forms a salt-bridge with Asp740, which triggers a conformational change producing the active protease plasmin (Pm). In contrast, streptokinase (SK) binds to Plgn to produce an initial inactive complex (SK·Plgn) which subsequently rearranges to an active complex (SK·Plgn*) although the Arg561,Val562 bond remains intact. Therefore another residue must substitute for the amino group of Val562 and provide a counterion for Asp740 in this active complex. Two candidates for this counterion have been suggested: Ile1 of streptokinase and Lys698 of Plgn. We have investigated the reaction of SK mutants and variants of the protease domain of microplasminogen (µPlgn) in order to determine if either of these residues is the counterion. The mutation of Ile1 of SK decreases the activity of SK·Plgn* by 100-fold (Ile1Val) to ,,104 -fold (Ile1,Ala, Gly, Trp or Lys). None of these mutations perturb the binding affinity of SK, which suggests that Ile1 is not required for formation of SK·Plgn but is necessary for SK·Plgn*. The substitution of Lys698 of µPlgn decreases the activity of SK·Plgn* by only 10,60-fold. In contrast with the Ile1 substitutions, the Lys698 mutations also decreased the dissociation constant of the SK complex by 15,50-fold. These observations suggest that Lys698 is involved in formation of the initial SK·Plgn complex. These results support the hypothesis that Ile1 provides the counterion for Asp740. [source] Expression of plasminogen activator inhibitor-1, urokinase receptor and laminin ,-2 chain is an early coordinated event in incipient oral squamous cell carcinomaINTERNATIONAL JOURNAL OF CANCER, Issue 12 2006Pia Lindberg Abstract Cancer cell invasion is facilitated by extracellular matrix degrading proteases such as plasmin. We have studied the expression of plasminogen activator inhibitor-1 (PAI-1) and urokinase receptor (uPAR) together with the ,2-chain of laminin-5 (lam-,2) by immunohistochemistry in 20 cases with incipient oral squamous cell carcinoma (SCC). PAI-1-positive neoplastic cells located at the tip of the putative invasive front of grade 1 (incipient) carcinoma were seen in 16 of the 20 cases (75%), whereas adjacent normal and dysplastic epithelium was PAI-1-negative. Clusters of putative invasive neoplastic cells located in the lamina propria were PAI-1-positive in areas with grade 2 incipient carcinoma as were invasive cancer cells in areas of grade 3,4 invasive carcinoma. uPAR immunoreactivity was strongly expressed in numerous stromal cells in the carcinoma area in all 20 lesions, while a few uPAR-positive stromal cells were found in areas with normal and dysplastic epithelium. uPAR-positive neoplastic cell islands located at the front of the lesions were seen in 15 of the 20 cases. The expression pattern of lam-,2 was very similar to that of PAI-1; however, lam-,2-positive neoplastic cells were only detected in 11 of the 20 cases (55%) in areas of grade 1 incipient carcinoma. Direct comparison of the 3 components revealed colocalization in neoplastic cell islands in both incipient and invasive SCC. Our results suggest that PAI-1 is a novel potential marker of initial invasion in oral SCC, and that the coordinated expression of PAI-1 with uPAR and lam-,2 sustain the features of the early invasive cancer cells. © 2006 Wiley-Liss, Inc. [source] Indigenous enzymatic activities in ovine and caprine milksINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2010GOLFO MOATSOU The objective of this review paper is the presentation of research findings about enzymes of ovine and caprine milks taking into consideration the bovine milk indigenous enzymatic activities as a reference. Information about indigenous enzymatic activities in these milk types focuses mainly on plasmin, lipoprotein lipase and on the enzymes that are used as thermal treatment indicators, i.e. alkaline phosphatase, and lactoperoxidase. Further research including the effects of genetic and environmental factors on the enzymatic activities is necessary. [source] Increased Bone Formation in Mice Lacking Plasminogen Activators,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2003E Daci Abstract Plasminogen activators tPA and uPA are involved in tissue remodeling, but their role in bone growth is undefined. Mice lacking tPA and uPA show increased bone formation and bone mass. The noncollagenous components of bone matrix are also increased, probably from defective degradation. This study underlines the importance of controlled bone matrix remodeling for normal endochondral ossification. Introduction: Proteolytic pathways are suggested to play a role in endochondral ossification. To elucidate the involvement of the plasminogen activators tPA and uPA in this process, we characterized the long bone phenotype in mice deficient in both tPA and uPA (tPA,/,:uPA,/,). Materials and Methods: Bones of 2- to 7-day-old tPA,/,:uPA,/, and wild-type (WT) mice were studied using bone histomorphometry, electron microscopy analysis, and biochemical assessment of bone matrix components. Cell-mediated degradation of metabolically labeled bone matrix, osteoblast proliferation, and osteoblast differentiation, both at the gene and protein level, were studied in vitro using cells derived from both genotypes. Results: Deficiency of the plasminogen activators led to elongation of the bones and to increased bone mass (25% more trabecular bone in the proximal tibial metaphysis), without altering the morphology of the growth plate. In addition, the composition of bone matrix was modified in plasminogen activator deficient mice, because an increased amount of proteoglycans (2×), osteocalcin (+45%), and fibronectin (+36%) was detected. Matrix degradation assays showed that plasminogen activators, by generating plasmin, participate in osteoblast-mediated degradation of the noncollagenous components of bone matrix. In addition, proliferation of primary osteoblasts derived from plasminogen activator-deficient mice was increased by 35%. Finally, osteoblast differentiation and formation of a mineralized bone matrix were enhanced in osteoblast cultures derived from tPA,/,:uPA,/, mice. Conclusions: The data presented indicate the importance of the plasminogen system in degradation of the noncollagenous components of bone matrix and suggest that the accumulation of these proteins in bone matrix,as occurs during plasminogen activator deficiency,may in turn stimulate osteoblast function, resulting in increased bone formation. [source] Toxic effect of blood components on perinatal rat subventricular zone cells and oligodendrocyte precursor cell proliferation, differentiation and migration in cultureJOURNAL OF NEUROCHEMISTRY, Issue 5 2009Packiasamy A. R. Juliet Abstract The germinal matrix of human brain gives rise to oligodendrocytes and astrocytes after mid-gestation. Hemorrhage in the germinal matrix of premature infants is associated with suppressed cell proliferation. We hypothesize that soluble blood constituents have an adverse effect on the proliferation of cultured rat subventricular zone (SVZ) cells and the proliferation, migration, and differentiation of oligodendrocyte progenitor cells (OPC). Using caspase 3 activation and lactate dehydrogenase release assays, rat plasma, serum, thrombin, and kallikrein killed SVZ cells when grown in the presence (but not absence) of platelet derived growth factor. Plasma and serum killed OPC at 1 : 1 to 1 : 100 dilutions. Using a bromodeoxyuridine incorporation assay OPC proliferation was reduced by plasma, serum, thrombin and plasmin. Blood proteins also suppressed OPC migration in a concentration dependent manner. However, differentiation of OPC into myelin basic protein expressing cells was suppressed only by thrombin. We conclude that soluble blood components, particularly thrombin, have an adverse effect on maturing SVZ cells and OPC derived from newborn rat brain. [source] Urokinase-type plasminogen activator inhibits amyloid-, neurotoxicity and fibrillogenesis via plasminogenJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2002H. Michael Tucker Abstract Amyloid-, (A,) appears central to Alzheimer's disease (AD), aggregates spontaneously, and is neurotoxic to neurons in vitro. Recently, several groups reported a familial AD locus on chromosome 10. Here, we note that urokinase-type plasminogen activator (uPA) is located within this locus. Previously, we reported that uPA and its functional homolog, tissue-type plasminogen activator, are induced by A, treatment of neurons in vitro as well as in a mouse model of A, accumulation in vivo. Moreover, the target of plasminogen activators, plasmin, degraded nonaggregated and aggregated A, and modulated A, toxicity and deposition. Here, we have evaluated the effects of uPA and plasminogen on A, fibril formation and neurotoxicity. We report that the combination of uPA and plasminogen, but neither alone, inhibits A, toxicity, reduces A, deposition in vitro, and inhibits A, fibrillogenesis. We interpret these observations as suggesting that uPA represents a possible candidate gene for the chromosome 10 familial AD locus. © 2002 Wiley-Liss, Inc. [source] Ethanol-Induced Up-Regulation of the Urokinase Receptor In Cultured Human Endothelial CellsALCOHOLISM, Issue 2 2001Edlue M. Tabengwa Background: Moderate alcohol consumption has been correlated to reduced coronary artery disease (CAD) risk and mortality. This alcohol effect may be mediated in part by an increased endothelial cell (EC) fibrinolysis. ECs synthesize fibrinolytic proteins, tissue plasminogen activator (t-PA), urokinase type plasminogen activator (u-PA), and plasminogen activator inhibitor type-1(PAI-1). In addition, they synthesize and regulate receptors for fibrinolytic proteins, namely (t-PA and plasminogen receptor) Annexin II and u-PA receptor (u-PAR). These receptors play an important role in the regulated expression of receptor-bound plasminogen activator conversion of receptor-bound plasminogen to receptor-bound plasmin on the EC surface (surface-localized fibrinolytic activity). Therefore, systemic factors, such as ethanol, that affect the level, or activity or interaction of one or more of these components, resulting in the increased expression of surface-localized EC fibrinolytic activity, will be expected to reduce the risk for thrombosis, CAD, and myocardial infarction (MI). We have previously shown that low ethanol up-regulates t-PA and u-PA gene transcription, while it down-regulates PAI-1, hence resulting in increased (sustained, 24 hr) surface-localized EC fibrinolytic activity. The current studies were carried out to determine whether low ethanol increased u-PAR expression in cultured human umbilical cord vein ECs (HUVECs). Methods: Cultured HUVECs were preincubated (1 hr) in the absence/presence of ethanol (0.025,0.2%, v/v); u-PAR mRNA (RT-PCR), antigen (western blot), and activity (125I-u-PA ligand binding/Scatchard analysis) levels were then measured after 0,24 hr. To determine whether the ethanol-induced changes in the u-PAR expression were transcriptional, transient transfection studies were carried out using a u-PAR/luciferase promoter construct (pu-PAR120/luc [1.2-kb u-PAR promoter fragment ligated to a promoterless luciferase vector]). Results: uPAR mRNA levels increased 2- to 3-fold and antigen levels (western blot) increased 2- to 4-fold while u-PA binding activity increased 36% (1.25 vs. 1.7 , 105 sites/cell, Bmax) without significantly affecting the Kd (1,2 nM). Transient transfection of cultured HUVECs with a pu-PAR120/luc construct resulted in a 2- to 3-fold increase in promoter activity in ethanol-induced cultures, compared with controls. Conclusion: These combined results demonstrate that low ethanol (,0.1%, v/v) induces the up-regulation of u-PAR gene transcription, resulting in increased u-PAR ligand binding activity. These results also further identify/define the contribution and role of another fibrinolytic protein in the overall ethanol-induced increase in surface-localized EC fibrinolysis that may underlie and contribute, in part, to the cardioprotection attributed to moderate alcohol consumption. [source] Ethanol-Induced Up-Regulation of Candidate Plasminogen Receptor Annexin II in Cultured Human Endothelial CellsALCOHOLISM, Issue 6 2000Edlue M. Tabengwa Introduction Epidemiological studies indicate that moderate alcohol consumption reduces the risk for coronary heart disease and that this cardioprotective benefit may be mediated, in part, by increased fibrinolysis. Endothelial cells (ECs) synthesize plasminogen activators, tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), receptors for plasminogen activators, and a receptor for plasminogen, annexin II (Ann-II). These receptors localize and facilitate receptor-bound plasminogen activator-mediated conversion of receptor-bound plasminogen to receptor-bound plasmin on the EC surface, which results in the regulated expression of surface-localized EC fibrinolytic activity. Ethanol is a systemic factor that affects these components, which increases EC fibrinolysis and hence reduces the risk for thrombosis, coronary heart disease, and myocardial infarction (MI). Methods: This study was carried out to determine whether low ethanol (0.1% v/v) increased plasminogen receptor, Ann-II antigen (western blot), messenger ribonucleic acid (mRNA) (reverse transcription polymerase chain reaction; RT-PCR) expression, activity (ligand binding/Scatchard analysis), and hence fibrinolysis (plasmin generation) in cultured human ECs. Results: Plasminogen receptor activity increased ,2-fold (2.5 vs. 5.6 × 106 sites/cell), as evidenced by increased 125I-labeled Glu-plasminogen ligand binding/Scatchard analysis. In addition, western blot analyses indicated an increase in Ann-II antigen, and mRNA levels increased ,2-fold (RT-PCR). This increase in Ann-II expression was concomitant with ,2- to 3-fold sustained increase (,24 hr) in surface-localized EC fibrinolytic activity. Nuclear transcription run-on assays showed an ,5- to 6-fold increase in new 32P-labeled Ann-II mRNA levels, compared with controls (no ethanol). Conclusions: These results demonstrated that low ethanol increased Ann-II antigen/mRNA levels and up-regulated Ann-II gene expression at the transcriptional level. The results further identify and define the contribution and role of the plasminogen receptor, Ann-II, in the ethanol-induced mechanism of increased EC fibrinolysis that may underlie and contribute, in part, to the cardioprotective benefit associated with moderate alcohol consumption. [source] Plasminogen on the surfaces of fibrin clots prevents adhesion of leukocytes and plateletsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2010V. K. LISHKO Summary.,Background and Objectives: Although leukocytes and platelets adhere to fibrin with alacrity in vitro, these cells do not readily accumulate on the surfaces of fibrin clots in vivo. The difference in the capacity of blood cell integrins to adhere to fibrin in vivo and in vitro is striking and implies the existence of a physiologic antiadhesive mechanism. The surfaces of fibrin clots in the circulation are continually exposed to plasma proteins, several of which can bind fibrin and influence cell adhesion. Recently, we have demonstrated that adsorption of soluble fibrinogen on the surface of a fibrin clot results in its deposition as a soft multilayer matrix, which prevents attachment of blood cells. In the present study, we demonstrate that another plasma protein, plasminogen, which is known to accumulate in the superficial layer of fibrin, exerts an antiadhesive effect. Results: After being coated with plasminogen, the surfaces of fibrin clots became essentially non-adhesive for U937 monocytic cells, blood monocytes, and platelets. The data revealed that activation of fibrin-bound plasminogen by the plasminogen-activating system assembled on adherent cells resulted in the generation of plasmin, which decomposed the superficial fibrin layer, resulting in cell detachment under flow. The surfaces generated after the initial cell adhesion remained non-adhesive for subsequent attachment of leukocytes and platelets. Conclusion: We propose that the limited degradation of fibrin by plasmin generated by adherent cells loosens the fibers on the clot surface, producing a mechanically unstable substrate that is unable to support firm integrin-mediated cell adhesion. [source] Pregnancy outcome and fibrinolytic, endothelial and coagulation markers in women undergoing uterine artery Doppler screening at 23 weeksJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2009B. J. HUNT Summary.,Background:,Pre-eclampsia (PET) and/or fetal growth restriction (FGR) remain a major cause of maternal and fetal morbidity and mortality. In pregnancy, fibrinolysis is controlled by the maternal endothelium and placenta, both of which are central to the pathogenesis of PET/FGR. Clinically, uterine artery Doppler screening at 23 weeks is used to predict PET/FGR. An abnormal uterine artery Doppler finding is defined as early diastolic bilateral uterine artery notching (BN) in the waveform. However, about 50% of mothers with BN do not develop PET/FGR. Objectives:,We investigated fibrinolytic changes and uterine artery Doppler findings in the second trimester, and related them to pregnancy outcome; in particular assessing whether fibrinolytic markers could discriminate between normal and abnormal outcome in mothers with BN. Patients/methods:,Plasma levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), plasminogen activator inhibitor-2 (PAI-2), plasmin-,2 antiplasmin (PAP), D-dimers and markers of endothelial dysfunction were measured with Doppler ultrasound at 23 weeks. Results:,Those with BN had decreased PAP and D-dimer levels, and raised PAI-1 and thrombomodulin levels. Mothers with BN and PET/FGR had significantly increased t-PA levels and reduced PAI-2 levels. Conclusions:,BN at 23 weeks of gestation is associated with increased PAI-1 levels. Within the BN group, mothers who developed PET/FGR had increased t-PA levels and decreased PAI-2 levels, although there was no net change in fibrinolysis as measured by D-dimer levels. No single fibrinolytic marker is helpful in determining pregnancy outcome in those with BN, but t-PA and PAI-2 are worthy of study in a multifactorial algorithm. [source] Fibrinolysis is amplified by converting ,2 -antiplasmin from a plasmin inhibitor to a substrateJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2007I. Y. SAZONOVA Summary., ,2 -antiplasmin (,2 -AP) is the fast serpin inhibitor of plasmin and appears to limit the success of treatment for thrombosis. We examined the mechanisms through which monoclonal antibodies (mAbs) against ,2 -AP amplify fibrinolysis. The mAbs RWR, 49 and 77 interfered with the ability of ,2 -AP to inhibit plasmin, microplasmin and trypsin. In solution, mAbs 49 and 77 bound to ,2 -AP with 5-fold to 10-fold higher relative affinity than mAb-RWR, while mAb-RWR bound with greater avidity to immobilized or denatured ,2 -AP. Binding studies with chimeric ,2 -APs revealed that none of the mAbs bound to sites in ,2 -AP that form putative contacts with plasmin, namely the carboxy terminal lysines of ,2 -AP, or the reactive center loop in the serpin domain of ,2 -AP. Rather, mAb-RWR recognized an epitope in the amino-terminus of ,2 -AP (L13GNQEPGGQTALKSPPGVCS32) near the site at which ,2 -AP cross-links to fibrin. mAbs 49 and 77 bound to another conformational epitope in the serpin domain of ,2 -AP. mAbs 49 and 77 markedly increased the stoichiometry of plasmin inhibition by ,2 -AP (from 1.1 ± 0.1 to 51 ± 4 and 67 ± 7) indicating that they convert ,2 -AP from an inhibitor to a substrate of plasmin. This was confirmed by sodium dodecylsulfate polyacrylamide gel electrophoresis analysis showing cleavage of ,2 -AP by plasmin in the presence of these mAbs. In summary, these mAbs appear to act at sites distinct from known ,2 -AP,plasmin contacts to enhance fibrinolysis by converting ,2 -AP from an inhibitor to a plasmin substrate. [source] Why ,2 -antiplasmin must be converted to a derivative form for optimal functionJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2007K. N. LEE Summary.,Background:,Human ,2 -antiplasmin (,2AP), the primary inhibitor of fibrinolysis, is secreted from the liver into plasma as a 464-residue protein with Met as the N-terminus. An R6W polymorphism has been suggested to affect fibrinolytic rate. Within circulating blood, antiplasmin-cleaving enzyme (APCE) cleaves Met-,2AP(R6) faster than Met-,2AP(W6) at the Pro12,Asn13 bond to yield Asn-,2AP. Objectives:,To compare Met-,2AP(R6), Met-,2AP(W6) and Asn-,2AP for crosslinking with fibrin and the ability to protect fibrin from digestion by plasmin. Methods and results:,Asn-,2AP utilizes Gln2 (Gln14 in Met-,2AP) to become crosslinked to fibrin approximately twelvefold faster than Met-,2AP(R6) or Met-,2AP(W6), and this enhances the resistance of fibrin to plasmin. All three forms of ,2AP inhibit plasmin at identical rates. The N-terminal 12-residue peptide of Met-,2AP slows crosslinking of Met-,2AP(R6) or Met-,2AP(W6) by limiting access of factor XIIIa to Gln14 rather than shifting crosslinking to other Gln residues. Edman sequencing and mass analyses of tryptic peptides from each ,2AP crosslinked with 5-(biotinamido)pentylamine showed Gln14 as the only major crosslinking site. Residues 5,8, GRQL in Met-,2AP(R6), and residues 1,8, MEPLGWQL in Met-,2AP(W6), slow fibrin crosslinking. Conclusion:,Gln14 in both Met-,2AP(R6) and Met-,2AP(W6) is sheltered by the N-terminal 12-residue peptide, which, when cleaved, yields Asn-,2AP, which is rapidly crosslinked to fibrin and maximally protects it from plasmin. The R6 W polymorphism in Met-,2AP does not affect its crosslinking to fibrin, but it does slow cleavage by APCE and reduces the amount of Asn-,2AP available for rapid crosslinking to fibrin. [source] Increased plasmin-,2-antiplasmin levels indicate activation of the fibrinolytic system in systemic amyloidosesJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2007B. BOUMA [source] The relative kinetics of clotting and lysis provide a biochemical rationale for the correlation between elevated fibrinogen and cardiovascular diseaseJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2007P. Y. KIM Summary.,Background:,Elevated plasma fibrinogen is a well known risk factor for cardiovascular disease. The mechanistic rationale for this is not known.Objectives:,These studies were carried out to determine the fibrinogen concentration dependencies of clotting and lysis times and thereby determine whether these times rationalize the correlation between an increased risk of cardiovascular disease and elevated plasma fibrinogen.Methods:,The time courses of clot formation and lysis were measured by turbidity in systems comprising a) fibrinogen, thrombin and plasmin, or b) fibrinogen, thrombin, plasminogen and t-PA, or c) plasma, thrombin and t-PA. From the lysis times, kcat and Km values for plasmin action on fibrin were determined.Results:,The time to clot increased linearly from 2.9 to 5.6 minutes as the fibrinogen concentration increased from 1 to 9 ,M and did not increase further as the fibrinogen concentration was raised to 20 ,M. In contrast, the clot lysis time increased linearly over the input fibrinogen concentration range of 2 to 20 ,M. A similar linear trend was found in the two systems with t-PA and plasminogen. Apparent Km and kcat values for plasmin were 1.1 ± 0.6 ,M and 28 ± 2 min,1, respectively. Km values for plasmin in experiments initiated with t-PA and plasminogen were 1.6 ± 0.2 ,M in the purified system and 2.1 ± 0.9 ,M in plasma.Conclusion:,As the concentration of fibrinogen increases, especially above physiologic level, the balance between fibrinolysis and clotting shifts toward the latter, providing a rationale for the increased risk of cardiovascular disease associated with elevated fibrinogen. [source] Plasma hemostatic factors and endothelial markers in four racial/ethnic groups: the MESA studyJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 12 2006P. L. LUTSEY Summary.,Background:,Hemostatic factors and endothelial markers may play some role in racial/ethnic differences in cardiovascular disease (CVD) rates. However, little information exists on hemostatic factors and endothelial markers across racial/ethnic groups. Objectives:,To describe, in four American racial/ethnic groups (Caucasian, Black, Hispanic, and Chinese), mean levels of selected hemostatic factors and endothelial markers. Patients and methods:,Multi-ethnic Study of Atherosclerosis baseline data were used (participant age: 45,84 years). Sex-specific analysis of covariance models, and t -tests for pairwise comparisons, were used to compare means of factors and markers. Adjustments were made for demographics and traditional CVD risk factors. Differences were significant at P < 0.05. Results:,Blacks had the highest levels of factor VIII, D-Dimer, plasmin,antiplasmin (PAP), and von Willebrand factor, among the highest levels of fibrinogen and E-selectin (women only), but among the lowest levels of intercellular adhesion molecule 1 (ICAM-1), and, in men, the lowest levels of plasminogen activator inhibitor-1 (PAI-1). Whites and Hispanics tended to have intermediate levels of factors and markers, although they had the highest levels of ICAM-1, and Hispanics had the highest mean levels of fibrinogen and E-selectin (women only). Chinese participants had among the highest levels of PAI-1, but the lowest, or among the lowest, of all other factors and markers. No soluble thrombomodulin differences were observed. Conclusions:,In this large cohort, hemostatic factor and endothelial marker mean levels varied by race/ethnicity, even after adjustment for traditional CVD risk factors. [source] Safety of plasmin in the setting of concomitant aspirin and heparin administration in an animal model of bleedingJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 12 2003S. Sadeghi Summary., Plasmin is a direct thrombolytic which has been shown to have a strikingly favorable benefit to risk profile in comparison with plasminogen activators, notably tissue plasminogen activator (t-PA). As heparin is known to increase the risk of hemorrhage when co-administered with a plasminogen activator, we asked whether adjunct antithrombotic agents such as aspirin and heparin would affect the safety of plasmin. Three groups of rabbits were administered plasmin at a dose (4 mg kg,1) designed to induce significant decreases in antiplasmin, fibrinogen and factor (F)VIII, to about 25, 40 and 40%, respectively, of baseline values, but not cause prolongation of the ear puncture bleeding time. In a blinded and randomized trial, the results show that an intravenous aspirin bolus plus heparin administered as a bolus followed by a maintenance continuous infusion did not significantly prolong the bleeding time during plasmin infusion. These data indicate that in the rabbit, concomitant use of aspirin plus heparin does not affect the safety of a therapeutic dose of plasmin. [source] Thrombin-activatable fibrinolysis inhibitor (TAFI, plasma procarboxypeptidase B, procarboxypeptidase R, procarboxypeptidase U)JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 7 2003B. N. Bouma Summary., Recently, a new inhibitor of fibrinolysis was described, which downregulated fibrinolysis after it was activated by thrombin, and was therefore named TAFI (thrombin-activatable fibrinolysis inhibitor; EC 3.4.17.20). TAFI turned out to be identical to the previously described proteins, procarboxypeptidase U, procarboxypeptidase R, and plasma procarboxypeptidase B. Activated TAFI (TAFIa) downregulates fibrinolysis by the removal of carboxy-terminal lysines from fibrin. These carboxy-terminal lysines are exposed upon limited proteolysis of fibrin by plasmin and act as ligands for the lysine-binding sites of plasminogen and tissue-type plasminogen activator (t-PA). Elimination of these lysines by TAFIa abrogates the fibrin cofactor function of t-PA-mediated plasminogen activation, resulting in a decreased rate of plasmin generation and thus downregulation of fibrinolysis. In this review, the characteristics of TAFI are summarized, with an emphasis on the pathways leading to activation of TAFI and the role of TAFIa in the inhibition of fibrinolysis. However, it cannot be ruled out that TAFI has other, as yet undefined, functions in biology. [source] Associations of factor VIIIc, D-dimer, and plasmin,antiplasmin with incident cardiovascular disease and all-cause mortalityAMERICAN JOURNAL OF HEMATOLOGY, Issue 6 2009Aaron R. Folsom To examine the associations of three understudied hemostatic factors,D-dimer, factor VIIIc, and plasmin-antiplasmin (PAP) complex,with incident cardiovascular disease (CVD) and all cause mortality in the Multiethnic Study of Atherosclerosis cohort. Hemostatic factors were measured at baseline in 45,84-year-old patients (n = 6,391) who were free of clinically recognized CVD. Over 4.6 years of follow-up, we identified 307 CVD events, 207 hard coronary heart disease events, and 210 deaths. D-dimer, factor VIIIc, and PAP were not associated with CVD incidence after adjustment for other risk factors. In contrast, each factor was associated positively with total mortality, and D-dimer and factor VIIIc were associated positively with cancer mortality. When modeled as ordinal variables and adjusted for risk factors, total mortality was greater by 33% (95% CI 15,54) for each quartile increment of D-dimer, 26% (11,44) for factor VIIIc, and 20% (4,38) for PAP. This prospective cohort study did not find D-dimer, factor VIIIc, or PAP to be risk factors for CVD. Instead, elevated levels of these three hemostatic factors were associated independently with increased risk of death. Elevated D-dimer and factor VIIIc were associated with increased cancer death. Am. J. Hematol., 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||