Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of cyclic strain on the production of tissue plasminogen activator (tPA) and type 1 plasminogen activator inhibitor (PAI-1) by cultured endothelial cells (EC) were examined. Human saphenous vein EC were seeded in selective areas of culture plates with flexible membrane bottoms (corresponding to specific strain regions) and grown to confluence. Membranes were deformed by vacuum (-20 kPa) at 60 cycles/min (0.5 s strain alternating with 0.5 s relaxation in the neutral position) for 5 days. EC grown in the periphery were subjected to 7-24% strain, while cells grown in the center experienced less than 7% strain. The results show a significant increase in immunoreactive tPA production on days 1, 3 and 5 compared to day 0 in EC subjected to more than 7% cyclic strain. There was no significant elevation of tPA in the medium of EC subjected to less than 7% strain. tPA activity could only be detected in the medium of EC subjected to more than 7% cyclic strain. PAI-1 levels in the medium were not significantly different in either group. In addition, immunocytochemical detection of intracellular tPA and messenger ribonucleic acid (mRNA) expression of tPA (assessed by the reverse transcriptase polymerase chain reaction utilizing tPA specific sense and antisense primers) was significantly increased in EC subjected to more than 7% cyclic strain. We conclude that a 60 cycles/min regimen of strain that is greater than 7% can selectively stimulate tPA production by EC in vitro and may contribute to the relative nonthrombogenicity of the endothelium in vivo.
 ...
PMID:Tissue plasminogen activator expression in endothelial cells exposed to cyclic strain in vitro. 128 45

Rat glomerular epithelial cells were grown to confluency on semipermeable tissue culture inserts and the plasminogen system of these cells was analyzed using enzyme assays, Western analysis, zymography, and reverse transcriptase-PCR. The glomerular epithelial cells are capable of activating exogenous plasminogen to plasmin by endogenous plasminogen activators. The cells produce both tissue-plasminogen activator and urokinase-plasminogen activator with urokinase being the prominent activator. Both activators are present primarily on the basolateral side of the cells with urokinase found primarily at the cell surface presumably bound to its receptor and tissue-plasminogen activator found primarily in the matrix secreted by the cells on the semipermeable insert. The cells also produce plasminogen activator inhibitor-1 and urokinase-plasminogen activator receptor. Inhibition of plasminogen activation occurred with plasminogen activator inhibitor-1, anti-catalytic anti-tissue-plasminogen activator antibody, epsilon-aminocaproic acid, which inhibits the binding of plasminogen through its lysine binding sites, and amiloride, which specifically inhibits urokinase.
 ...
PMID:Analysis of the plasminogen system on rat glomerular epithelial cells. 779 90

We examined mRNA expressions of urokinase-type plasminogen activator (u-PA), its specific receptor (u-PR), and plasminogen activator inhibitors (PAI-1 and PAI-2) in 50 human breast cancers by the reverse transcriptase-polymerase chain reaction method. The expressions of the genes are discussed in relation to the clinicopathological findings. In the overall population in breast cancers, a low level of PAI-2 expression was significantly associated with lymph node involvement (P < 0.0001). The u-PA, u-PR, and PAM expressions tended to be at high levels in such metastatic cancers. Also, positive expression of u-PA, u-PR, and PAI-1 was significantly correlated with negative expression of PAI-2. These results indicate that PAI-2 may play a critical role in the regulation of extracellular matrix degradation during tumor cell invasion and metastasis, and the expression of PAI-2 may be useful as a marker to evaluate the prognosis of breast cancers.
 ...
PMID:Inverse correlation between mRNA expression of plasminogen activator inhibitor-2 and lymph node metastasis in human breast cancer. 864 85

Rat proximal tubular epithelial cells derived from Wistar-Kyoto and spontaneously hypertensive rats were grown to confluency on semipermeable tissue culture inserts, and the plasminogen system of these cells was analyzed using enzyme assays, Western analysis, zymography, and reverse transcriptase-polymerase chain reaction. The tubular epithelial cells are capable of activating exogenous plasminogen to plasmin by endogenous plasminogen activators. The cells produce tissue-plasminogen activator, urokinase-plasminogen activator, plasminogen activator inhibitor-1, and urokinase-plasminogen activator receptor. These cells also produce the Heymann nephritis autoantigen, gp330 (megalin), and an associated protein of 45 kd (RAP). Incubation with transforming growth factor-beta 1 resulted in a decrease in plasminogen activation, primarily because of an increase in plasminogen activator inhibitor-1 RNA and protein and a decrease in u-PA RNA as noted by quantitative reverse transcriptase-polymerase chain reaction, Western analysis, and zymography. Incubation of these cells with tumor necrosis factor-alpha resulted in an increase in plasminogen activating ability, presumably through an increase in urokinase. Gp330 and the associated 45-kd protein (RAP) RNA were decreased in cells treated with tumor necrosis factor-alpha. The data presented indicates that these transformed proximal tubular epithelial cells may be used to study changes that may occur during Heymann nephritis with respect to the plasminogen system and the autoantigen gp330.
 ...
PMID:Effect of TGF-beta 1 and TNF-alpha on the plasminogen system of rat proximal tubular epithelial cells. 904 36

Altered expression of plasminogen activator inhibitors (PAIs) is of potential relevance to the process of lung fibrosis. To clarify the involvement of PAIs in interstitial lung diseases, we examined whether alterations in PAI-1 and PAI-2 were induced in response to a single intratracheal administration of a fibrosing dose of crystalline silica in mice (5 mg x animal(-1)). The time course of changes in PAI activity and PAI-1 protein were characterized in bronchoalveolar lavage fluid (BALF) and changes in PAI-1 and PAI-2 messenger ribonucleic acid (mRNAs) were monitored by reverse transcriptase polymerase chain reaction (RT-PCR) in BALF cells and lung tissue up to the fibrotic stage of the disease. Substantial levels of PAI activity were found in BALF of control animals, whereas no PAI-1 protein was detected. In response to silica treatment, we observed an acute increase of PAI activity and PAI-1 protein levels in BALF (day 1), associated with an induction of PAI-1 and PAI-2 mRNA levels in lung tissue. In alveolar macrophages, silica treatment induced a persistent upregulation of PAI-2 mRNA only. One month after silica treatment, PAI activity was undetectable in BALF while substantial PAI activity was still present in controls. At the same time point, sustained upregulation of PAI-1 and PAI- 2 mRNAs was, however, noted in lung tissue of animals treated with silica. These findings support the possible implication of PAIs in the remodelling process induced by silica in the lung.
 ...
PMID:Expression of plasminogen activator inhibitors type-1 and type-2 in the mouse lung after administration of crystalline silica. 962 97

The expression of urokinase-type plasminogen activator (u-PA), u-PA receptor (u-PAR) and plasminogen activator inhibitor (PAI) 1 and 2 was examined in 105 cases of primary lung cancer tissue using immunohistochemical staining and reverse transcriptase polymerase chain reaction (RT-PCR) techniques. The expression of u-PA, u-PAR and PAI-1 was detected in approximately 80% of primary lung cancers, whereas detectable PAI-2 expression was observed only in half of the overall cases. We assessed the relationships between the expression pattern and clinicopathological findings and found that a diminished expression level of PAI-2 was significantly correlated with lymph node metastasis and a poor prognosis. These results indicate that PAI-2 may play a critical role in the regulation of extracellular matrix degradation during tumour cell invasion and metastasis, and the expression of PAI-2 may be useful as a marker for evaluating the prognosis of lung cancer.
 ...
PMID:Significance of plasminogen activator inhibitor 2 as a prognostic marker in primary lung cancer: association of decreased plasminogen activator inhibitor 2 with lymph node metastasis. 974 10

Urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA) play important roles in fibrinolysis, cell migration, tissue destruction, angiogenesis and tissue remodeling. u-PA and t-PA activity in tissue are tightly regulated by plasminogen activator inhibitor-1 (PAI-1). However, little is known of the activity of endogenous plasminogen activators (PAs) and PAI-1 in ischemic brain. To evaluate whether cerebral ischemic injury induces endogenous PAs and PAI-1, we measured PA activity from brain homogenates, and examined the expression of t-PA mRNA, u-PA mRNA and PAI-1 mRNA from brain homogenates in C57BL/6J mice (n=45) weighing 29-35 g in which the middle cerebral artery (MCA) was occluded by a fibrin-rich clot. Brain homogenates were prepared for direct casein zymography from control non-ischemic mice (n=4) and mice at 2 h (n=5), 4 h (n=5), and 24 h (n=4) after MCA occlusion (MCAO). Also, u-PA and t-PA knockout mice at 4 h (n=2, each) after MCAO were used as a negative control for direct casein zymography. Frozen sections for in situ zymography were obtained from control mice (n=2) and mice at 2 h, 4 h, and 24 h (n=2, per time point) after clot occlusion. Brain homogenates were prepared for reverse transcriptase-polymerase chain reaction (RT-PCR) to examine t-PA mRNA, u-PA mRNA and PAI-1 mRNA expression from control non-ischemic mice (n=4) and mice at 2 h (n=5), 4 h (n=5), and 24 h (n=5) after MCAO. By direct casein zymography, u-PA activity increased at 4 h (P<0.05), and 24 h (P<0.05) after stroke in the ischemic hemisphere compared with the non-ischemic mice. Activity of t-PA in ischemic brain was not significantly different from the control group. As measured by in situ zymography, PA activity, most likely u-PA, was present in the ischemic hemisphere. By RT-PCR, expression of PAI-1 mRNA, but not u-PA mRNA and t-PA mRNA, increased 3-, 15- and 25-folds in the ischemic hemisphere at 2 h, 4 h and 24 h after stroke, respectively, compared with control mice. This study demonstrates that PAI-1 mRNA and u-PA activity increase in mouse brain after stroke.
 ...
PMID:Endogenous plasminogen activator expression after embolic focal cerebral ischemia in mice. 1043 99

The occurrence of protein C inhibitor (PCI) in human platelets and megakaryocytes was analyzed. As judged from enzyme-linked immunosorbent assays (ELISAs), PCI was present in platelets at a concentration of 160 ng/2 x 10(9) cells. Its specific activity was 5 times higher than that of plasma PCI. Consistently, mainly the 57-kD form (active PCI) and some high molecular weight (M(r)) forms, but no bands corresponding to cleaved PCI, were detected when platelet lysates were immunoprecipitated with monoclonal anti-PCI-IgG and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. The localization of PCI in platelets was studied by immunofluorescence histochemistry and immunotransmission electron microscopy: PCI was detected in alpha granules, in the open canalicular system, and on the plasma membrane. At these sites, colocalization with plasminogen activator inhibitor-1 was seen. Studies were performed to clarify whether platelet PCI is endogenously synthesized or taken up from plasma. Internalization of biotinylated-PCI was analyzed using platelets in suspension and gold-labeled streptavidin for visualization of incorporated biotin. Dose- and time-dependent uptake of PCI was found. PCI mRNA was detected in platelets by reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blotting, as well as in megakaryocytes by in situ hybridization of human bone marrow cryosections. We therefore conclude that platelets contain a functionally active PCI pool that is derived from both endogenous synthesis as well as internalization.
 ...
PMID:Synthesis and ultrastructural localization of protein C inhibitor in human platelets and megakaryocytes. 1074 91

Transforming growth factor beta1 (TGF-beta1) and matrix metalloproteinases (MMPs) produced by tumor cells play important roles in tumor invasion. PSK, a protein-bound polysaccharide, is widely used in Japan as an immunopotentiating biological response modifier for cancer patients. In this study, we focused on the effects of PSK on invasiveness, TGF-beta1 production, and MMPs expression in two human tumor cell lines, pancreatic cancer cell line (NOR-P1) and gastric cancer cell line (MK-1P3). PSK significantly decreased the invasiveness of both cell lines through Matrigel-coated filters but did not affect cell viability, proliferation, or adhesion. Decreased invasion was associated with the inhibition of TGF-beta1, MMP-2, and MMP-9 at both mRNA and protein levels as assessed by reverse transcriptase-polymerase chain reaction, gelatin zymography, and enzyme-linked immunosorbent assay. Antibody against TGF-beta1 neutralized the MMP activities of both cell lines. PSK also suppressed the expression of urokinase plasminogen activator (uPA) and uPA receptor but did not change plasminogen activator inhibitor-1 (PAI-1) expression. Western blot analysis showed that PSK reduced uPA protein expression but not PAI-1 expression in the both cell lines. These results indicate that PSK suppresses tumor cell invasiveness through down-regulation of several invasion-related factors including TGF-beta1, uPA, MMP-2, and MMP-9.
 ...
PMID:Protein-bound polysaccharide PSK inhibits tumor invasiveness by down-regulation of TGF-beta1 and MMPs. 1144 66

Human endothelial cells synthesize and secrete a variety of molecules involved in fibrinolysis and coagulation. The effects of a low molecular weight heparin, Bemiparin, and unfractionated heparin (UFH) were compared on plasminogen activator inhibitor-1 (PAI-1), tissue-plasminogen activator (t-PA), tissue factor (TF), tissue factor pathway inhibitor (TFPI) release, and PAI-1 gene expression by human umbilical vein endothelial cells (HUVEC). Cell cultures were supplemented with Bemiparin or UFH at 1 or 10 U/mL. Culture media samples were obtained before the addition of the drugs and 2, 6, and 24 hours afterward to measure the antigen levels of TF, TFPI, t-PA, and PAI-1. RNA was obtained to study the endothelial expression of PAI-1 by reverse transcriptase-polymerase chain reaction (RT-PCR). Bemiparin at 1 U/mL resulted in a decreased messenger RNA (mRNA) PAI-1 expression, which remained unaltered when UFH had been added. PAI-1 levels increased after the cultures had been supplemented with either Bemiparin or UFH at both doses. UFH induced an increase in t-PA either at 1 or 10 U/mL. Both doses of UFH, but not Bemiparin, induced an important increase in TF secretion. An increase in the TFPI levels was seen with UFH at 1 U/mL. The decrease in PAI-1 gene expression observed with a therapeutic dose of Bemiparin might confer this drug interesting profibrinolytic properties. The fact that Bemiparin, in contrast with UFH, does not induce an increase in TF could give this drug another positive feature.
 ...
PMID:Effects of a low molecular weight heparin, bemiparin, and unfractionated heparin on hemostatic properties of endothelium. 1199 Dec 42


1 2 Next >>