TCF is the nuclear effector of the beta-catenin signal that patterns the sea urchin animal-vegetal axis

The mechanism of animal-vegetal (AV) axis formation in the sea urchin embryo is incompletely understood. Specification of the axis is thought to involve a combination of cell-cell signals and as yet unidentified maternal determinants. In Xenopus the Wnt pathway plays a crucial role in defining the embryonic axes. Recent experiments in sea urchins have shown that at least two components of the Wnt signaling pathway, GSK3beta and beta-catenin, are involved in embryonic AV axis patterning. These results support the notion that the developmental network that regulates axial patterning in deuterostomes is evolutionarily conserved. To further test this hypothesis, we have examined the role of beta-catenin nuclear binding partners, members of the TCF family of transcriptional regulators, in sea urchin AV axis patterning. To test the role of TCFs in mediating beta-catenin signals in sea urchin AV axis development we examined the consequences of microinjecting RNAs encoding altered forms of TCF on sea urchin development. We show that expression of a dominant negative TCF results in a classic "animalized" embryo. In contrast, microinjected RNA encoding an activated TCF produces a highly "vegetalized" embryo. We show that the transactivational activity of endogenous sea urchin TCF is potentiated by LiCl treatment, which vegetalizes embryos by inhibiting GSK3, consistent with an in vivo interaction between endogenous beta-catenin and TCF. We also provide evidence indicating that all of beta-catenin's activity in patterning the sea urchin AV axis is mediated by TCF. Using a glucocorticoid-responsive TCF, we show that TCF transcriptional activity affects specification along the AV axis between fertilization and the 60-cell stage.

Tissue factor pathway inhibitor activity associated with LDL is inactivated by cell- and copper-mediated oxidation

Human plasma contains a multivalent, Kunitz-type proteinase inhibitor termed tissue factor pathway inhibitor (TFPI), which is a specific inhibitor of the action of the factor VII(a)-tissue factor complex in coagulation. A major fraction of plasma TFPI is transported in association with LDL. Because LDL may undergo oxidation in the arterial wall during atherogenesis, we examined the effect of copper- and cell-mediated oxidative modification on TFPI activity associated with LDL. Oxidation mediated by copper ions resulted in a significant inactivation of LDL-associated TFPI (60% to 72% at 24 hours with 2.5 mumol/l CuCl2). The inactivation of TFPI was strongly negatively correlated with both an increase in the net electrical charge of LDL (r = -.80, P < or = .0001) and with the production of thiobarbituric acid-reactive substances (r = -.78, P < or = .0001) and lipid peroxides (r = -.80, P < or = .0001). Cell-mediated oxidation, involving incubation of LDL for 48 hours with either monocyte-like THP1 cells or human monocytes in Ham's F-10 medium, effected a significant decrease (64% and 75%, respectively) in LDL-associated TFPI activity. By contrast, prolonged exposure of LDL to purified soybean lipoxygenase (5000 U/mL) was less effective in inactivating TFPI (47% reduction after incubation for 72 hours at 37 degrees C). We subsequently investigated the mechanism(s) that may underlie such inactivation. Oxidation of LDL is accompanied by the generation of various aldehydes, including malondialdehyde and 4-hydroxynonenal. Chemical modification with these aldehydes revealed a significant inverse correlation between the progressive loss of TFPI activity and both the increase in net electrical charge (r = -.90, P < or = .0001) and the derivatization of free amino acid residues of LDL (r = -.90, P < or = .0001). Specific chemical modification of lysine amino groups by acetylation similarly led to inactivation of LDL-associated TFPI activity. TFPI activity was almost totally abolished (< 1.4%) when the TNBS reactivities of acetylated LDL, malondialdehyde-modified LDL, and 4-hydroxynonenal-modified LDL were 31%, 21%, and 43% that of native LDL, respectively. Our data demonstrate that expression of LDL-associated anticoagulant activity is markedly decreased as a consequence of the oxidative process, and suggest that the progressive aldehydic derivatization of apo B of LDL, and of the associated TFPI protein, may contribute to this phenomenon. Because tissue factor is overexpressed in the atheromatous plaque, it may exert a marked local procoagulant effect.(ABSTRACT TRUNCATED AT 400 WORDS)

Anticoagulant activity of tissue factor pathway inhibitor in human plasma is preferentially associated with dense subspecies of LDL and HDL and with Lp(a)

Human plasma contains a multivalent, Kunitz-type proteinase inhibitor termed tissue factor pathway inhibitor (TFPI), which specifically inhibits the action of the factor VII(a)-tissue factor complex in coagulation. In the present study, we examined the distribution and anticoagulant activity of TFPI among plasma lipoprotein subspecies separated by isopycnic density gradient ultracentrifugation; this procedure permitted the simultaneous fractionation of the major lipoprotein classes (very-low-density lipoprotein [VLDL], intermediate-density lipoprotein [IDL], low-density lipoprotein [LDL], high-density lipoprotein [HDL] 2 and 3, and very-high-density lipoprotein [VHDL]). Studies of eight normolipidemic subjects revealed two major lipoprotein carriers of TFPI activity: dense LDL subspecies (d = 1.039 to 1.063 g/mL) and both dense HDL particles and VHDL (d = 1.133 to 1.190 g/mL), representing 33.8% and 35.9%, respectively, of the total lipoprotein-associated TFPI activity in plasma. TFPI activity was also associated with lipoprotein(a) (Lp[a]), whose density distribution (d = 1.044 to 1.100 g/mL) overlapped that of LDL and HDL2; such association was related to Lp(a)'s particle size and phenotype. VLDL, IDL, and LDL1 through LDL3 (d = 1.019 to 1.039 g/mL), HDL2 (d = 1.063 to 1.100 g/mL), and light subfractions of HDL3 (d = 1.100 to 1.167 g/mL) conveyed only 1.8%, 10%, and 18.5%, respectively, of lipoprotein-associated TFPI activity. Such anticoagulant activity was dependent on the presence of TFPI protein. The dense subspecies of HDL3 (d = 1.133 to 1.167 g/mL) with which TFPI was preferentially associated were small, displayed a cholesteryl ester to protein ratio of approximately 0.2, and were deficient in phospholipid (13.6% to 18.3%). HDL subspecies of d = 1.110 to 1.167 g/mL mainly contained the higher relative molecular mass form of TFPI of 41 kD (a form that is known to be covalently associated with apolipoprotein [apo] A-II) and minor bands of the 35- and 52-kD forms. The second major localization of TFPI was within the hydrated density range of small, dense LDL particles (d = 1.033 to 1.063 g/mL), which in comparison with light LDL (d = 1.019 to 1.033 g/mL) exhibited a markedly lower proportion of triglyceride and enrichment in cholesteryl ester.(ABSTRACT TRUNCATED AT 400 WORDS)

Overexpression of nucleoside diphosphate kinase (Nm23) in solid tumours

The product of the nm23-H1 gene, reported to be related to the metastatic potential of tumour cells, was recently identified as the nucleoside diphosphate (NDP) kinase A (Gilles et al., 1991, J Biol Chem, 266, 8784-8789). An analysis of the enzyme by activity measurement and immunological techniques using polyclonal antibodies raised against the NDP kinase A purified from human erythrocytes, was performed on 39 human tissue specimens. Markedly increased activity and higher level of the protein were observed in extracts of solid tumours as compared to the corresponding normal tissues (P less than 0.01). An intense immunolabelling of tumoral cells was observed in sections of the malignant tumours and of some but not all benign neoplasia. The staining is observed in noninvasive and invasive ductal breast carcinomas with or without lymph node involvement as well as in colon and cervix carcinomas and in a case of metastatic melanoma. Therefore, NDP kinase A level is increased in neoplastic tissues but no correlation with metastatic potential could be demonstrated.

The significance of low antithrombin III levels in cirrhosis

Antithrombin III is an anticoagulant synthesized in the liver cells. The aim of this study was to estimate the serum level of antithrombin III in cirrhotics. Investigations were carried out in 32 patients with cirrhosis and in 20 healthy controls. Antithrombin III measured by radial immunodiffusion was found significantly lower (19.2 +/- 6.8 mg%) than in controls (28.0 +/- +/- 5.2 mg%) (p less than 0.01). The level of antithrombin III is positively correlated with pseudo-cholinesterase and, less significantly with blood albumin. Therefore decreased antithrombin III reflects liver cell disfunction in cirrhosis and its decrease may predispose to thrombotic events which occur sporadically in cirrhosis.

Nucleoside diphosphate kinase from human erythrocytes. Structural characterization of the two polypeptide chains responsible for heterogeneity of the hexameric enzyme

Human erythrocyte nucleoside-diphosphate kinase (NDP kinase) is a hexameric enzyme consisting of two kinds of polypeptide chains, A and B. By random association (A6, A5B...AB5, B6) these polypeptides form isoenzymes differing in their isoelectric point. Chains A and B of NDP kinase were purified by ion-exchange chromatography under denaturing conditions. Upon mixing and renaturation, the isozymic pattern of NDP kinase obtained by conventional methods was restored. Antibodies raised against purified chains showed significant cross-reactivity, both in immunoblot experiments and activity inhibition studies. Sequence determination showed that both chains consisted of 152 amino acid residues corresponding to Mr or 17,143 (chain A) and 17,294 (chain B), respectively. There was high homology between the two sequences (88% identity). The phosphorylation site on the enzyme is located at His-118. Chain A was identical with human Nm23 protein, which has been reported as a potential suppressor protein in tumor metastasis and chain B was identical with Nm23-H2 protein.

Functional and antigenic antithrombin III in angina pectoris and acute myocardial infarction patients

Plasma antithrombin III was measured by an immunological approach (AT III:Ag) using an antiserum developed in our laboratory and by its ability to inhibit thrombin (functional assay) using a chromogenic synthetic substrate in 12 patients with myocardial infarction, 9 patients with angina pectoris and 10 healthy control subjects. In the early stage (3 to 24 hours after the onset of pain) of an acute myocardial infarction AT III:Ag (115.67% +/- 21.23) was found to be significantly (p less than 0.01) higher than functional (free) AT III (92% +/- 10.27). This difference was less obvious 10 days later (AT III:Ag 118% +/- 18.93; functional AT III 104.94 +/- 14.45). There was also no significant difference between AT III:Ag and functional AT III in patients with angina pectoris as well as in controls. Since AT III:Ag represents total plasma AT III while functional AT III represents only free AT III the difference between these two variables could provide informations about the amount of the anticoagulant forming complexes with activated clotting factors. It is therefore considered that the significant increase in the difference between AT III:Ag and functional AT III in the early stage of acute myocardial infarction is likely to suggest an intravascular activation of coagulation.

Nucleoside diphosphate kinase from human erythrocytes: purification, molecular mass and subunit structure

A new procedure for the purification of nucleoside diphosphate kinase from human erythrocytes is described. The enzyme (105 kDa by gel filtration) is made-up of two different kinds of subunits (19.0 and 20.5 kDa), both displaying enzymatic activity. The probable subunit structure of the enzyme is hexameric. The discrepancies related to earlier work are discussed.

Clinical studies on plasma antithrombin III using an antiserum prepared in our laboratories

Using an antiserum obtained in rabbits injected with antithrombin III purified in our laboratories, the plasma level of this inhibitor of coagulation was found to be significantly (p less than 0.001) decreased in 8 patients with decompensated cirrhosis of the liver (15.66 mg/dl +/- 2.22) and in 18 nephrotic patients (21.74 mg/dl +/- 1.75). When compared to values noted in 22 normal-weight normolipidemic control subjects (31.54 mg/dl +/- 0.81), the plasma level of antithrombin III was slightly (p less than 0.05) higher in the 18 hyperlipidemic subjects (36.11 mg/dl +/- 1.9). Owing to an extremely wide dispersion of individual values, the mean level of antithrombin III noted in 16 critically ill postoperative patients (28.16 mg/dl +/- 2.98) did not significantly differ from control values, although this protease inhibitor was obviously decreased in those postoperative patients who developed multiple organ failure or disseminated intravascular-coagulation. Among the 11 patients with recurrent venous thrombosis, two subjects with familial deficiency in antithrombin III were detected. The results provide evidence that the antiserum prepared in our laboratories is a useful tool for detecting acquired and inherited antithrombin III deficiencies.