Structural basis for inhibition of carboxypeptidase B by selenium-containing inhibitor: selenium coordinates to zinc in enzyme.

Activated thrombin-activatable fibrinolysis inhibitor (TAFIa) is a zinc-containing carboxypeptidase and significantly inhibits fibrinolysis. TAFIa inhibitors are thus expected to act as profibrinolytic agents. We recently reported the design and synthesis of selenium-containing inhibitors of TAFIa and their inhibitory activity.

Nobiletin, a polymethoxyflavone in citrus fruits, reduces TAFI expression in HepG2 cells through transcriptional inhibition.

Thrombin-activatable fibrinolysis inhibitor (TAFI, carboxypeptidase B2) is a 58-kDa plasma glycoprotein secreted by hepatocytes as an inactive form. TAFI is activated by the thrombin-thrombomodulin complex, and activated TAFI (TAFIa) plays an important role in regulating the balance between coagulation and fibrinolysis through inhibition of fibrinolysis. It has been suggested that high levels of TAFI in circulating plasma increase the risks of cardiovascular death and acute phase in ischaemic stroke.

Thrombomodulin, a novel molecule regulating inorganic phosphate-induced vascular smooth muscle cell calcification.

Hyperphosphatemia has emerged as a cardiovascular risk factor that stimulates calcification in vessels. We explored molecules that were induced by inorganic phosphate (Pi) at an early stage in vascular smooth muscle cells (VSMC). In the present study, we examined the role of thrombomodulin (TM) in Pi-induced VSMC calcification based on the results of DNA microarray analysis.

Design and characterization of a selenium-containing inhibitor of activated thrombin-activatable fibrinolysis inhibitor (TAFIa), a zinc-containing metalloprotease.

Available therapies for thromboembolic disorders include thrombolytics, anticoagulants, and antiplatelets, but these are associated with complications such as bleeding. To develop an alternative drug which is clinically safe, we focused on activated thrombin-activatable fibrinolysis inhibitor (TAFIa) as the target molecule. TAFIa is a zinc-containing carboxypeptidase that significantly inhibits fibrinolysis.

Intravenous and oral administrations of DD2 [7-Amino-2-(sulfanylmethyl)heptanoic acid] produce thrombolysis through inhibition of plasma TAFIa in rats with tissue factor-induced microthrombosis.

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a plasma zymogen that is activated by thrombin in plasma. In fibrinolytic processes, carboxy-terminal lysine (Lys) residues in partially degraded fibrin are important sites for plasminogen binding and activation, and an active form of TAFI (TAFIa) inhibits fibrinolysis by eliminating these residues proteolytically. We synthesized DD2 [7-Amino-2-(sulfanylmethyl)heptanoic acid], a Lys analogue containing sulfur, as an inhibitor of TAFIa and investigated its pharmacological profile and pathophysiological role in thrombolysis via in vitro and in vivo studies.

Peroxisome proliferator-activated receptor-alpha agonists repress expression of thrombin-activatable fibrinolysis inhibitor by decreasing transcript stability.

Thrombin-activatable fibrinolysis inhibitor (TAFI) (carboxypeptidase B2) is a plasma zymogen that is biosynthesised in the liver and released into the circulation. Activated TAFI is a prothrombotic factor which inhibits fibrin clot lysis. Cultured human hepatoma HepG2 cells were treated with peroxisome proliferator-activated receptor (PPAR)α, β or γ agonists, and the levels of TAFI antigen and mRNA (here, termed CPB2 mRNA) were measured.

Cytotoxic effects of hydroxylated fullerenes on isolated rat hepatocytes via mitochondrial dysfunction.

The cytotoxic effects of hydroxylated fullerenes, also termed fullerenols or fullerols [C(60)(OH)( n )], which are known nanomaterials and water-soluble fullerene derivatives, were studied in freshly isolated rat hepatocytes. The exposure of hepatocytes to C(60)(OH)(24) caused not only concentration (0-0.25 mM)- and time (0-3 h)-dependent cell death accompanied by the formation of cell blebs, loss of cellular ATP, reduced glutathione (GSH), and protein thiol levels, but also the accumulation of glutathione disulfide and malondialdehyde, indicating lipid peroxidation.

Mitochondrial dysfunction and biotransformation of β-carboline alkaloids, harmine and harmaline, on isolated rat hepatocytes.

The cytotoxic effects and biotransformation of harmine and harmaline, which are known β-carboline alkaloids and potent hallucinogens, were studied in freshly isolated rat hepatocytes. The exposure of hepatocytes to harmine caused not only concentration (0-0.50mM)- and time (0-3h)-dependent cell death accompanied by the formation of cell blebs and the loss of cellular ATP, reduced glutathione, and protein thiols but also the accumulation of glutathione disulfide.

Expression of thrombin-activatable fibrinolysis inhibitor (TAFI) is up-regulated by increase in intracellular cyclic AMP levels in cultured HepG2 cells.

Thrombin-activatable fibrinolysis inhibitor (TAFI), a carboxypeptidase B-like proenzyme, is predominantly biosynthesised in the liver and released into circulating plasma. Activated TAFI has a role in maintaining the balance between blood coagulation and fibrinolysis. We investigated the regulation of TAFI expression in cultured human hepatoma HepG2 cells.

Biotransformation and cytotoxic effects of hydroxychavicol, an intermediate of safrole metabolism, in isolated rat hepatocytes.

The biotransformation and cytotoxic effects of hydroxychavicol (HC; 1-allyl-3,4-dihydroxybenzene), which is a catecholic component in piper betel leaf and a major intermediary metabolite of safrole in rats and humans, was studied in freshly isolated rat hepatocytes. The exposure of hepatocytes to HC caused not only concentration (0.25-1.

EF6265, a novel inhibitor of activated thrombin-activatable fibrinolysis inhibitor, protects against sepsis-induced organ dysfunction in rats.

Objective: Although thrombin-activatable fibrinolysis inhibitor (TAFI) has been implicated as a negative regulator of fibrinolysis, its pathophysiological significance remains to be unveiled. We performed the pharmacologic study to assess the effect of EF6265, a specific inhibitor of activated form of TAFI (TAFIa) on sepsis-induced organ dysfunction models.

Design: A controlled, in vivo laboratory study.

Thrombomodulin suppresses invasiveness of HT1080 tumor cells by reducing plasminogen activation on the cell surface through activation of thrombin-activatable fibrinolysis inhibitor.

Cell malignancy is negatively correlated with the expression of thrombomodulin (TM), a thrombin receptor expressed on the surface of various cells, including tumor cells. TM accelerates thrombin-activatable fibrinolysis inhibitor (TAFI) activation catalyzed by thrombin. The active form of TAFI (TAFIa) contributes to inhibition of plasmin formation through its carboxypeptidase B (CPB)-like activity.

Cytotoxic effects of 3,4-methylenedioxy-N-alkylamphetamines, MDMA and its analogues, on isolated rat hepatocytes.

The amphetamine-derived designer drugs have been illegally used worldwide as recreational drugs, some of which are known to be hepatotoxic in humans. To compare their cytotoxic effects, 3,4-methylenedioxy-N-methamphetamine (MDMA) and its related analogues, N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB), 3,4-(methylenedioxyphenyl)-2-butanamine (BDB) and 2-methylamino-1-(3,4-methylenedioxyphenyl)-propane-1-one (methylone) were studied in freshly isolated rat hepatocytes. MBDB caused not only concentration (0-4.

Sp1 is an essential transcription factor for LPS-induced tissue factor expression in THP-1 monocytic cells, and nobiletin represses the expression through inhibition of NF-kappaB, AP-1, and Sp1 activation.

Nobiletin is a citrus polymethoxylated flavonoid extracted from Citrus depressa, and has several reported biological effects. In this study, we investigated the effect of nobiletin on bacterial lipopolysaccharide (LPS)-induced expression of tissue factor (TF), a trigger protein for the blood coagulation cascade, and studied the possible mechanism of TF transcriptional regulation. THP-1 monocytic cells stimulated with LPS showed an increased expression of both TF protein and mRNA levels.

EF6265, a novel plasma carboxypeptidase B inhibitor, protects against renal dysfunction in rat thrombotic glomerulonephritis through enhancing fibrinolysis.

Background/aim: Plasma carboxypeptidase B is a physiological fibrinolysis inhibitor. In the present study, the effects of EF6265, a novel specific plasma carboxypeptidase B inhibitor, on renal dysfunction in a rat thrombotic glomerulonephritis model were examined.

Methods: The model was induced by injection of anti-glomerular basement membrane serum and lipopolysaccharide to rats.

ATP-generating glycolytic substrates prevent N-nitrosofenfluramine-induced cytotoxicity in isolated rat hepatocytes.

The relationship between cytotoxicity induced by N-nitrosofenfluramine and mitochondrial or glycolytic adenosine triphosphate (ATP) synthesis-dependent intracellular bioenergetics was studied in isolated rat hepatocytes. The supplementation of fructose, an ATP-generating glycolytic substrate, to hepatocyte suspensions prevented N-nitrosofenfluramine-induced cell injury accompanied by the formation of cell blebs, abrupt loss of intracellular ATP and reduced glutathione and mitochondrial membrane potential (DeltaPsi), and the accumulation of oxidized glutathione and malondialdehyde, indicating lipid peroxidation, during a 2h incubation period. Fructose (1-20mM) resulted in concentration-dependent protection against the cytotoxicity of N-nitrosofenfluramine at a concentration of 0.

Verotoxin-1 stimulation of macrophage-like THP-1 cells up-regulates tissue factor expression through activation of c-Yes tyrosine kinase: Possible signal transduction in tissue factor up-regulation.

Verotoxin (VT)-producing Escherichia coli (E. coli) O157:H7 infections are frequently complicated by thrombotic angiopathy, hemolytic uremic syndrome (HUS) and neurological symptoms. The present data demonstrate that VT-1 (Shiga toxin) stimulation of macrophage-like THP-1 cells up-regulates the activity, antigen and mRNA levels of tissue factor (TF), a key cofactor of the coagulation-inflammation-thrombosis circuit.

Thrombomodulin induction in cultured human endothelial cells by 9-cis-locked retinoic acid analogues.

9-cis-Retinoic acid (RA) analogues devised to lock the 9-cis double bond by ring formation were synthesized using two stereoselective carbon-carbon bond formation reactions as key steps. The palladium-mediated Suzuki reaction was adopted to construct a 7E-double bond (RA numbering) and the Horner-Emmons olefination was employed for stereoselective 11E-double bond (RA numbering) formation. The synthesized 9-cis-RA analogues that are locked by five-membered ring systems (cyclopentene, dihydrofuran, and dihydrothiophene) were shown to have comparable thrombomodulin induction activities to that of 9-cis RA.

Pharmacological characterization of the active synthetic factor Xa inhibitors M55551 and M55165.

Factor Xa plays an important role in blood coagulation and is widely regarded as an attractive target for antithrombotic drug development. M55551 and M55165 (1-arylsulfonyl-3-piperazinone derivatives) are novel synthetic factor Xa inhibitors. In vitro, M55551 and M55165 competitively inhibited factor Xa with K(i) values of 3.

Enhancement of fibrinolysis by EF6265 [(S)-7-amino-2-[[[(R)-2-methyl-1-(3-phenylpropanoylamino)propyl]hydroxyphosphinoyl] methyl]heptanoic acid], a specific inhibitor of plasma carboxypeptidase B.

Plasma procarboxypeptidase B, also known as thrombin-activatable fibrinolysis inhibitor (TAFI), is converted by thrombin into the active enzyme, carboxypeptidase B (CPB)/activated TAFI. Plasma CPB down-regulates fibrinolysis by removing carboxy-terminal lysines, the ligands for plasminogen and tissue-type plasminogen activator (tPA), from partially degraded fibrin. To target thrombosis in a new way, we have identified and optimized a phosphinic acid-containing inhibitor of CPB, EF6265 [(S)-7-amino-2-[[[(R)-2-methyl-1-(3-phenylpropanoylamino) propyl]hydroxyphosphinoyl]methyl]heptanoic acid] and determined both the pharmacological profile and pathophysiological role of CPB in rat thrombolysis.

Expression of thrombomodulin in human aortic smooth muscle cells with special reference to atherosclerotic lesion types and age differences.

Expression of thrombomodulin (TM) in atherosclerotic lesions of the human aorta (8 cases of diffuse intimal thickening, 4 fatty streaks, 11 atheromatous plaques, and 5 fibrous plaques) as well as in undiseased aortas of 5 infants obtained at autopsy was studied immunohistochemically using a novel polyclonal antibody against human TM. TM was expressed in intimal smooth muscle cells (SMC) besides endothelial cells and foamy macrophages in almost all patients (26/28). In addition, medial SMC in adult cases over 27 years of age expressed TM.

Thrombomodulin expression by THP-1 but not by vascular endothelial cells is upregulated by pioglitazone.

Thrombomodulin-protein C pathway is a major anti-thrombotic mechanism present in endothelial cells (EC), and an important modulator of inflammation. Peroxisomal proliferator activated receptor-gamma (PPARgamma) expressed in monocytes/macrophages may have a role in cell differentiation. Since the expression of thrombomodulin (TM) by monocytes is upregulated during differentiation into macrophages, we investigated the effect of pioglitazone, a thiazolidinedione (TZD) that is a synthetic ligand of PPARgamma, on the expression of TM by a human monocyte/macrophage cell line; human acute monocytic leukemia (THP-1) cells.

Pitavastatin-induced thrombomodulin expression by endothelial cells acts via inhibition of small G proteins of the Rho family.

Objective: 3-hydroxyl-3-methyl coenzyme A reductase inhibitors (statins) can function to protect the vasculature in a manner that is independent of their lipid-lowering activity. The main feature of the antithrombotic properties of endothelial cells is an increase in the expression of thrombomodulin (TM) without induction of tissue factor (TF) expression. We investigated the effect of statins on the expression of TM and TF by endothelial cells.

Carboxypeptidase B inhibitors reduce tissue factor-induced renal microthrombi in rats.

Procarboxypeptidase B (also known as thrombin-activatable fibrinolysis inhibitor) is a recently described plasma zymogen known to be activated by thrombin in plasma. Carboxy-terminal lysine residues from partially degraded fibrin are important for the binding and activation of plasminogen, and carboxypeptidase B, an active form of procarboxypeptidase B, has been shown to inhibit fibrinolysis by eliminating these residues. The present paper investigates the effects of carboxypeptidase B inhibitors, DL-mercaptomethyl-3-guanidinoethylthiopropanoic acid (MGPA) and potato-derived carboxypeptidase inhibitor (CPI), on tissue factor (TF)-induced microthrombosis in rats.