Molecular cloning and tissue distribution of mouse protein C inhibitor (PCI).
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Animals↗
Biomedical subjects
B R Binder
Publications and source records attributed to B R Binder.
Effect of protein C inhibitor (PCI) on in vitro fertilization.
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Animals↗
Protein C inhibitor (PCI).
PCI is a non-specific serpin that inhibits several proteases of the coagulation and fibrinolytic systems as well as plasma- and tissue kallikreins and the sperm protease acrosin. The precise physiological role of PCI has not been defined yet. Heparin stimulates most PCI/protease reactions, but interferes with the tissue kallikrein/PCI-interaction. Thereby heparin not only regulates PCI-activity but also its specificity in systems containing two or more of its target proteases. This effect is not restricted to heparin, but is also seen with other glycosaminoglycans (GAGs) and large, negatively charged molecules. PCI also binds to GAGs present on the surface of epithelial kidney cells, and GAGs isolated from these cells have a similar effect on PCI activity as heparin. Studies analyzing the role of PCI as an acrosin inhibitor revealed that endogenous PCI is immunocytochemically localized to disrupted acrosomal membranes of morphologically abnormal sperms, while intact sperms are negative for PCI-antigen. In a mouse in vitro fertilization model human PCI inhibited sperm/egg binding and decreased the fertilization rate. Northern blotting of human and mouse mRNA using human and mouse PCI-cDNA probes revealed that in the mouse PCI is exclusively synthesized in the genital tract (testis, seminal vesicle, ovary), while in humans PCI is additionally synthesized in many other organs (e.g., liver, pancreas, heart). Therefore PCI might regulate enzymes involved in fertilization (e.g. acrosin) in both species. Other proteases (e.g., tissue kallikrein) are possibly regulated in a species specific manner by different inhibitors.
Animals↗
Role of granulocyte elastase in the formation of hemorrhagic shock-induced gastric mucosal lesions in the rat.
OBJECTIVE: To investigate the mechanism by which activated leukocytes induce gastric mucosal lesions, we examined whether granulocyte elastase is involved in the formation of such lesions in a rat model of hemorrhagic shock. DESIGN: Prospective, randomized, controlled study. SETTING: Research laboratory at a university medical center. SUBJECTS: Male Wistar rats, weighing 220 to 280 g. INTERVENTIONS: Animals were subjected to hemorrhagic shock by phlebotomy. ONO-5046, a granulocyte elastase inhibitor (300 mg/kg ip), was administered 30 mins before or after phlebotomy. The effects of antithrombotic substances and tranexamic acid on hemorrhagic shock-induced gastric mucosal lesions also were examined. The effects of granulocyte elastase on the thrombomodulin activity and 35S-glycosaminoglycan content of endothelial cells were examined, using cultured human umbilical vein endothelial cells.
Animals↗
Isolation and characterization of tissue-type plasminogen activator- binding proteoglycans from human umbilical vein endothelial cells.
We analyzed the tissue-type plasminogen activator (TPA)-binding proteoglycans (PGs) on human umbilical vein endothelial cells (HUVECs), which were metabolically labeled with [35S]NA2SO4. Cell extracts were then prepared and subjected to affinity chromatography on diisopropyl fluorophosphate (DFP)-inactivated TPA-Sepharose 4B. Approximately 6% of the incorporated 35S radioactivity bound to DFP-treated TPA-Sepharose 4B and was eluted with 2 mol/L NaCl. In addition to NaCl, heparin, arginine, and lysine but not glycine, epsilon-amino-n-caproic acid or aspartic acid inhibited this binding and eluted the bound 35S radioactivity. Urea-containing polyacrylamide gel electrophoresis of the eluted material consistently revealed two main signals of 35S radioactivity (one with an M(r) between 600,000 and 750,000 [PGA] and the other with an M(r) between 120,000 and 180,000 [PGC]). Occasionally a less intense signal with an M(r) between 340,000 and 440,000 (PGB) was seen. Heparitinase treatment markedly decreased the intensities of both 35S signals (PGA and PGB), and chondroitinases AC and ABC abolished the 35S signal of PGC, indicating that most of the HUVEC-incorporated radioactivity with an affinity for TPA could be attributed to heparan sulfate- and chondroitin sulfate-like structures. Reductive elimination, which was performed to separate the possible glycosaminoglycan moieties from the core proteins, confirmed the PG-like nature of this material and again revealed heparan sulfate and chondroitin sulfate as the major glycosaminoglycan components. We therefore conclude that HUVECs synthesize TPA-binding, heparan sulfate- and chondroitin sulfate-containing PGs. In vivo, similar PGs may play a role in TPA binding to endothelial cells and thereby possibly influence TPA activity and/or provide an intravascular storage pool of TPA.
Cells, Cultured↗
Serum albumin is a specific inhibitor of apoptosis in human endothelial cells.
Excess blood vessels are removed by apoptosis of endothelial cells, however, the signals responsible for this have not been defined. Apoptosis of cultured human umbilical vein endothelial cells is induced by deprivation of serum or adhesion. In this paper, apoptosis in human umbilical vein and microvascular endothelium was induced by deprivation of serum and or adhesion. Apoptosis was confirmed on the basis of morphology, ultrastructure and internucleosomal cleavage of DNA. Loss of endothelial adhesion was found to be an early event in cultured endothelial cell apoptosis and was exploited to quantitate apoptosis. The effect of: bovine serum albumin; human serum albumin; recombinant human albumin; dithiothreitol reduced human and bovine albumin; CNBr treated human and bovine albumin as well as ovalbumin upon endothelial apoptosis was determined. Native bovine and human albumin as well as recombinant human material inhibited apoptosis at physiological concentrations with identical dose response curves in both umbilical vein and microvascular cells. Dithiothreitol treatment destroyed all protective activity while bovine but not human albumin was partially inactivated by CNBr treatment. The unrelated protein ovalbumin was not protective. Albumin did not inhibit apoptosis if cells were also deprived of adhesion. The data suggest that albumin is a specific inhibitor of human endothelial apoptosis but does not protect cells also deprived of adhesion. Reduced supply of albumin to endothelium in poorly perfused blood vessels may provide a mechanism for the removal of excess blood vessels in remodelling tissues. Also, the failure of albumin to protect endothelial cells deprived of adhesion from apoptosis may reflect the need to remove potentially micro-embolic cells detached due to trauma.
Apoptosis↗
High precision measurement of electrical resistance across endothelial cell monolayers.
Effects of vasoactive agonists on endothelial permeability was assessed by measurement of transendothelial electrical resistance (TEER) of human umbilical vein endothelial cells (HUVECs) grown on porous polycarbonate supports. Because of the low values of TEER obtained in this preparation (< 5 omega cm2) a design of an Ussing type recording chamber was chosen that provided for a homogeneous electric field across the monolayer and for proper correction of series resistances. Precision current pulses and appropriate rates of sampling and averaging of the voltage signal allowed for measurement of < 0.1 omega resistance changes of the endothelium on top of a 21 omega series resistance of the support and bathing fluid layers. Histamine (10 microM) and thrombin (10 U/ml) induced an abrupt and substantial decrease of TEER, bradykinin (1 microM) was less effective, PAF (380 nM) and LTC4 (1 microM) had no effect. TEER was also reduced by the calcium ionophore A-23187 (10 microM). The technique allows for measurements of TEER in low resistance monolayer cultures with high precision and time resolution. The results obtained extend previous observations in providing quantitative data on the increase of permeability of HUVECs in response to vasoactive agonists.
Bradykinin↗
Growth and fibrinolytic parameters of human umbilical vein endothelial cells seeded onto cardiovascular grafts.
It was the aim of this study to investigate possible effects of biomaterials used to produce vascular grafts on the fibrinolytic system of endothelial cells. Therefore growth conditions for human umbilical vein endothelial cells on polytetrafluoroethylene and on polyurethane were optimized. Tissue culture polystyrene was used as a control material. We could demonstrate that precoating of the materials with fibronectin significantly increased the growth rate of human umbilical vein endothelial cells on these materials. Furthermore, we showed that human umbilical vein endothelial cells grown on polytetrafluoroethylene or polyurethane released more plasminogen activator inhibitor-1 and tissue type-plasminogen activator into the conditioned media than did human umbilical vein endothelial cells grown on tissue culture polystyrene. Human umbilical vein endothelial cells cultured on polytetrafluoroethylene also deposited more plasminogen activator inhibitor-1 into the extracellular matrix than did control cells grown on tissue culture polystyrene. Our results give evidence that human umbilical vein endothelial cells grown on two biomaterials used to construct vascular grafts, namely polytetrafluoroethylene and polyurethane, produce tissue-type plasminogen activator as well as plasminogen activator inhibitor-1, two major components of the fibrinolytic system also expressed by endothelial cells in vivo. In conclusion, our data suggest that endothelial cells grown on vascular grafts show functional integrity concerning their fibrinolytic system, which in turn might contribute to reduce the thrombogenic properties of the graft material.
Biocompatible Materials↗
No association of APC resistance with myocardial infarction.
Resistance to activated protein C (APC resistance) due to the factor V mutation 506 Arg-->Gln (factor V Leiden) is the most prevalent inherited risk factor for venous thromboembolism. Its association with arterial thromboembolic disease, however, is still controversial. In the present study we found no difference between the prevalence of APC resistance (assessed by the ratio of the aPTT with and without added APC) in 134 non-anticoagulated survivors of myocardial infarction and that in 100 controls of similar age and sex distribution (2.2% and 2.0%, respectively). Patients showed a significantly higher median value for the aPTT ratio than controls (2.85 and 2.66, respectively), a fact we could not explain by our data.
Adult↗
Endothelial cell injury induced by plasmin in vitro.
We investigated the effect of plasmin on the integrity and function of endothelial cells to elucidate the mechanism by which bleeding or rethrombosis may be induced in thrombolytic therapy. When incubated with cultured human umbilical vein endothelial cells (HUVECs), plasmin increased the endothelial permeability to serum albumin 10 minutes after the incubation. Plasmin damaged the cell membranes 30 minutes after the incubation, detached the cells from the matrix 3 hours after the incubation, and finally induced cell lysis. Such damaging effects on HUVECs were not observed with plasminogen or plasmin pretreated with aprotinin and alpha 2-plasmin inhibitor, suggesting that the catalytic function of plasmin plays an important role in inducing this damage. Sulfur 35-labeled glycosaminoglycans (35S-GAGs) of HUVECs were decreased 1 hour after the incubation of plasmin with HUVECs, and the thrombomodulin (TM) activity of HUVECs measured by protein C activation capacity was decreased 6 hours after the incubation. Neither 35S-GAGs nor the TM activity of HUVECs was decreased after the incubation of plasmin pretreated with aprotinin and alpha 2-plasmin inhibitor. These findings suggest that the nonthrombogenic properties of endothelial cells can be damaged by the proteolytic action of plasmin. Our findings, taken together, suggest that plasmin damages the endothelial barrier function, endothelial cell integrity, and nonthrombogenic properties. These damaging effects of plasmin on endothelial cells may be related to the pathophysiology of bleeding or rethrombosis observed in patients undergoing high-dose thrombolytic therapy for thrombosis.
Cell Membrane Permeability↗
The antibody to plasminogen activator inhibitor-1 suppresses pulmonary metastases of human fibrosarcoma in athymic mice.
We studied the effects of the plasminogen activator inhibitor-1 (PAI-1), the urokinase-type plasminogen activator (uPA) and their antibodies on hematogeneous pulmonary metastases formation of human fibrosarcoma in athymic mice. We used a human fibrosarcoma cell line (HT-1 080) with low metastatic potential, and a subpopulation of HT-1 080 (HT-1 080-P4) with high metastatic potential which was selected by repeating injections into the tail veins of athymic mice. We examined the effects of these drugs on pulmonary metastases formation according to Wexler's method and the number of tumor cell emboli in the lung subsequent to an injection of radio-labeled tumor cells. Pulmonary metastases formation from HT-1 080 was not affected by any of the tested drugs. Pulmonary metastases from HT-1 080-P4 increased with uPA and anti-uPA antibody injections. PAI-1 slightly increased pulmonary metastases from HT-1 080-P4, and the anti-PAI-1 antibody decreased it (60.9 + 27.7% of control, p < 0.05). While none of the drugs altered the number of HT-1 080 cells in the lung at 24, 48 and 72 hours after the injection, PAI-1 increased the number of HT-1 080-P4 cells in the lung, whereas uPA and PAI-1 decreased it. The result that these drugs did not affect the metastatic potential of HT-1 080 but only that of HT-1 080-P4, indicates that fibrinolysis plays an important role in hematogenous pulmonary metastases formation of tumor cells with high metastatic potential. The effects of uPA suggest that uPA facilitates pulmonary metastasis formation probably due to an increase in the invasive ability of tumor cells. The effects of PAI-1 and its antibody of HT-1 080-P4 cells suggest that PAI-1 may facilitate tumor cell lodgement in vessels and the anti-PAI-1 antibody could be able to suppress pulmonary metastases of tumor cells with high metastatic potential by inhibition of tumor cell lodgement in vessels.
Animals↗
Fibrinolytic system of cultured rabbit aortic endothelial cells.
The fibrinolytic system of rabbit aortic endothelial cells (RAECs) isolated from male New Zealand White rabbits was investigated. The components of the fibrinolytic system in the conditioned media (CM) were analysed by SDS-PAGE followed by fibrin autography and reverse fibrin autography. The major lytic zones appeared at 54 and 70 KD and minor lytic zones could be detected between 100 and 120 KD. A plasminogen activator inhibitor was localised at 50 KD. Addition of amiloride abolished the lytic zones at 54 KD and 100 KD. There was a time dependent increase in plasminogen activator and inhibitor activities as revealed by an assay involving plasminogen and chromogenic plasmin substrate. A plateau was reached after 16-20 hours. When mRNA obtained from RAECs cultured for 16 hours in serum free medium was analysed for the presence of specific messages of tissue type plasminogen activator (t-PA), urokinase type plasminogen activator (u-PA) and plasminogen activator inhibitor 1 (PAI-1) using human probes, weak specific binding could be seen for both t-PA and mu-PA while the PAI-1 probe gave a strong specific signal at 3.4 Kb and a weak signal at 2.3 Kb. Both thrombin (1U/ml) and endotoxin (100 ng/ml) increased the release of PAI-1 activity into CM significantly, while there was no significant change in PAs. The increase of PAI-1 was reflected by increased PAI-1 mRNA levels. The data suggests that rabbit ECs can be used to investigate endothelial cell mediated fibrinolysis and supplement results obtained in investigations employing the rabbit as an in vivo animal model to study the fibrinolytic system.
Animals↗
Hepatocyte growth factor stimulates expression of plasminogen activator inhibitor type 1 and tissue factor in HepG2 cells.
HGF is a powerful mitogen for both rat and human hepatocytes, epithelial cells and endothelial cells in vitro, and is angiogenic in vivo. It has considerable homology with plasminogen and has been shown to upregulate urokinase-type plasminogen activator (u-PA) in endothelial cells as well as u-PA and its receptor in kidney epithelial cells. In this study, we report that human recombinant HGF stimulates expression of plasminogen activator inhibitor type 1 (PAI-1) and tissue factor (TF) in the human hepatoma cell line HepG2. PAI-1 antigen as determined by a specific enzyme-linked immunosorbent assay increased up to threefold in conditioned media of HepG2. This increase was dose dependent with maximum stimulation achieved with a concentration of 50 ng/mL of hepatocyte growth factor (HGF). PAI-1 antigen also increased up to fourfold in the extracellular matrix in HGF treated HepG2. The production of the PAI-1 binding protein vitronectin (Vn) was not affected by HGF. In contrast, TF activity in HepG2 treated with HGF increased up to twofold. As determined by Northern blotting, PAI-1 and TF-specific mRNA were increased significantly in the presence of HGF, whereas Vn mRNA was not affected. The increase in PAI-1 and TF mRNA was also seen when HepG2 were incubated with HGF in the presence of cycloheximide, thereby indicating that de novo protein synthesis is not required to mediate the effect. u-PA could be detected neither in unstimulated or HGF-stimulated HepG2 cells on the antigen level nor on the mRNA level. In conclusion, our data give evidence that HGF, in addition to its proliferative effect for different cell types, is also involved in the local regulation of fibrinolysis and coagulation. One could speculate that HGF might modulate processes requiring matrix degradation by increasing the expression of the protease u-PA in one cell type and by upregulating the expression of the serine protease inhibitor PAI-1 in a different cell type. Because u-PA has been shown to activate latent HGF to the active form, it could furthermore be speculated that by upregulating PAI-1, which in turn could inhibit u-PA, HGF might regulate its own activation.
Carcinoma, Hepatocellular↗
Binding of urinary protein C inhibitor to cultured human epithelial kidney tumor cells (TCL-598). The role of glycosaminoglycans present on the luminal cell surface.
Binding of urinary protein C inhibitor (PCI) to cultured human epithelial kidney tumor cells (TCL-598) was studied. Binding was dose-dependent, time-dependent, and saturable. Heparin interfered in a dose-dependent way with PCI binding to TCL-598 as did heparan sulfate and to a lesser degree also dermatan sulfate. Pretreatment of TCL-598 with protamine sulfate inhibited subsequent binding of PCI in a dose-dependent manner and > 100 micrograms/ml protamine sulfate reduced binding of PCI to < 10% of the control. Binding of 125I-PCI was specific, and bound 125I-PCI was recovered from the cells by heparin treatment or detached together with intact cells by EDTA treatment, migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the same mobility (M(r) = 57,000) as unbound 125I-PCI. Furthermore, cell-bound PCI was functionally active as judged from its ability to inhibit the amidolytic activity of urokinase, and its inhibitory activity was stimulated approximately 3-4-fold as compared to fluid-phase PCI. Immunogold electron microscopy revealed that PCI-antigen presented to the cells from the luminal side bound exclusively to that surface in native as well as in prefixed cells. This binding of PCI was abolished in the presence of heparin (50 micrograms/ml) and after pretreatment of the cells either with protamine sulfate (400 micrograms/ml) or with heparinase III (0.5 unit/ml). A slight decrease in PCI binding was seen after pretreatment of the cells with chondroitinase ABC and chondroitinase AC. In contrast, binding of PCI to extracellular matrices of TCL-598 was decreased to approximately 70% after chondroitinase ABC treatment of the extracellular matrices, whereas both heparinase III or chondroitinase AC treatment only reduced matrix-bound PCI to approximately 95%. These data suggest that heparan sulfate-containing proteoglycans are predominantly involved in binding of PCI to the luminal side of TCL-598, while dermatan sulfate-containing proteoglycans, the overall predominant PCI-binding proteoglycans in TCL extracts, are responsible for PCI binding to the extracellular matrix. Heparan sulfate, however, exposed to an environment containing PCI under physiological conditions, might localize PCI and modulate its target enzyme specificity in vivo.
Carbohydrate Sequence↗
Effect of type-1 plasminogen activator inhibitor on human leukocyte elastase.
When human leukocyte elastase (HLE) activity (1.0 microgram/ml) was analysed in the presence of PAI-1 (0.15.0 micrograms/ml), HLE activity, measured with the low molecular weight paranitroanilide substrate L-pyroglutamyl-prolyl-L-valine-p-nitroanilide was increased time and dose dependently (a plateau of stimulation was reached after 30 minutes) with a simultaneous decrease in PAI-1 inhibitory activity. This effect was neither influenced by the presence of vitronectin nor heparin. When PAI-1 was converted into its latent form by incubation for 48 hours at 37 degrees C or incubated with an excess of recombinant t-PA to convert free PAI-1 into t-PA-PAI-1 complexes, the stimulatory effect of both the latent and the complexed form of PAI-1 was significantly greater than that of the active form. Analysing HLE PAI-1 interaction on a molecular level using SDS-PAGE, no SDS stable complex formation between HLE and PAI-1 could be observed but lower molecular weight cleavage products of PAI-1 were generated. The stimulatory effect of PAI-1 on HLE activity was not restricted to the low molecular weight pNA-substrate but was also revealed using a natural substrate assay (bovine neck ligament elastin solubilization). Therefore interaction of HLE and PAI-1 seems not to be restricted just to decrease PAI-1 activity but would simultaneously also increase HLE activity, thereby supporting enzymatic activity necessary for migration of leukocytes, dissolution of blood clots and tissue remodelling.
Glycoproteins↗
The somatomedin B domain of vitronectin. Structural requirements for the binding and stabilization of active type 1 plasminogen activator inhibitor.
We recently localized the high affinity binding site for activated type 1 plasminogen activator inhibitor (PAI-1) to the somatomedin B domain (i.e. amino acid (aa) 1-51) of vitronectin (Vn). In this study to further define this site, N-terminal Vn fragments of various lengths were expressed in Escherichia coli and tested for PAI-1 binding activity. Vn polypeptides containing aa 1-52 and 1-40 retained PAI-1 binding activity and stabilized PAI-1 to a similar extent as intact Vn, but polypeptides containing aa 1-30 did not bind to PAI-1 nor stabilize its activity. The effects of monoclonal antibodies (mAbs) to Vn on PAI-1 binding was also determined. One mAb bound to Vn and blocked its ability to bind to PAI-1. It also dissociated pre-existing PAI-1.Vn complexes, and prevented the incorporation of PAI-1 into extracellular matrix of HT 1080 cells. This mAb bound to the recombinant peptide containing aa 1-40, but not to the peptide consisting of aa 1-30. A second randomly chosen mAb with similar affinity for Vn was inactive in these assays and bound to the region between aa 52 and 239. These results indicate that the high affinity binding site for active PAI-1 in Vn is between aa 1 and 40, and that this domain may also stabilize active PAI-1.
Amino Acid Sequence↗
Direct evidence for systemic fibrinogenolysis in patients with acquired alpha 2-plasmin inhibitor deficiency.
To examine whether or not acquired alpha 2-plasmin inhibitor deficiency is associated with systemic fibrinogenolysis, we analyzed the fibrin and fibrinogen degradation products in eight patients with this condition in various disease states. The underlying disease was gastric cancer in three patients, metastatic prostatic cancer in two, acute promyelocytic leukemia in two, and abdominal aortic aneurysm in one patient. In all eight patients, the alpha 2-plasmin inhibitor level was reduced to less than 50% of normal, and plasmin-alpha 2-plasmin inhibitor complex levels were increased. Immunoblotting of serum using an antifibrinogen antibody detected a 250 kDa protein (corresponding to fragments X or DY) in all eight patients. Fragment Y and D monomer were detected in seven of the eight patients, indicating the occurrence of systemic fibrinogenolysis. However, they were not detected in one patient with metastatic prostatic cancer. To determine whether or not fibrinogen degradation was also occurring in the patient without fragment Y, we characterized the 250 kDa protein in all eight patients. The protein was found to be fragment X in the metastatic prostatic cancer patient without fragment Y, while it was fragment DY in the other seven patients. Thus, systemic fibrinogenolysis was present in all eight patients. In the two patients with metastatic prostatic cancer, the level of alpha 2-plasmin inhibitor gradually increased with the reduction of tumor size by treatment. Fragment X, fragment Y, and D monomer were not detected when the alpha 2-plasmin inhibitor level exceeded 60% of normal in both patients. In the other six patients fragment Y and D monomer also disappeared when the alpha 2-plasmin inhibitor level exceeded 60% of normal. These findings suggest that systemic fibrinogenolysis only occurs when the plasma levels of alpha 2-plasmin inhibitor falls below 60% of normal due to activation of the fibrinolytic system by various pathological conditions.
Adult↗
Inhibition of acrosin by protein C inhibitor and localization of protein C inhibitor to spermatozoa.
Protein C inhibitor (PCI) is synthesized by cells throughout the male reproductive tract and is present in high concentrations (220 micrograms/ml) in seminal plasma. Seminal plasma as well as the acrosome of spermatozoa are rich in possible target proteases for PCI. We analyzed the interaction of PCI with acrosin, a serine protease stored in its zymogen form in the acrosome of spermatozoa. Purified human PCI inhibited the amidolytic activity of purified boar acrosin with an apparent second-order rate constant of 3.7 x 10(4) M-1.s-1. Inhibition was paralleled by the degradation of PCI from its 57- to its 54-kDa form. Human PCI also inhibited the amidolytic activity of activated human sperm extracts and formed complexes with acrosin as determined by an enzyme-linked immunosorbent assay. Immunocytochemistry revealed that morphologically abnormal spermatozoa stained for PCI antigen, whereas morphologically normal spermatozoa were negative. In immunoelectron microscopy, PCI was exclusively localized in the immediate vicinity of disrupted acrosomal membranes of sperm heads. These data suggest that PCI might function as a scavenger of prematurely activated acrosin, thereby protecting intact surrounding cells and seminal plasma proteins from possible proteolytic damage.
Acrosin↗