Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We carried out an immunohistochemical study of tissue-type plasminogen activator (PA) and urokinase-type PA, and their inhibitors, PA inhibitor-1 and PA inhibitor-2, using renal biopsy specimens obtained from 86 patients with various forms of glomerulonephritis. The controls were four normal renal tissue specimens. On immunofluorescent observation, granular staining for tissue-type PA was found to be distributed along the glomerular capillary walls. The fluorescence was weak in the normal renal tissue and occasionally intense in the tissues of patients with IgA nephritis, minimal change nephrotic syndrome, and lupus nephritis. PA inhibitor-1 was abundant in the glomerular epithelial cells and scarce in the mesangial area and glomerular capillary lumens of the normal renal tissues. This was confirmed by immunoelectron microscopy using gold staining. The fluorescence of PA inhibitor-1 was weaker in some specimens of nephritic tissues than in the normal renal tissues. Urokinase-type PA and PA inhibitor-2 were negative within the glomeruli in all the specimens. In the glomerulonephritic tissues which were fibrin deposition-positive, tissue-type PA expression in the glomeruli tended to be strong. An association between fibrin deposition and PA inhibitor-1 staining was not clear. These data suggest that expression of tissue-type PA in the glomeruli increases in association with fibrin deposition.
 ...
PMID:Tissue-type plasminogen activator and its inhibitor in human glomerulonephritis. 138 27

Expression of plasminogen activator (PA) enzyme activity is believed to be one of the mechanisms by which malignant cells cause pericellular proteolysis of stromal structures during implantation and tissue invasion. In this study, four cell lines derived from human gliomas were studied to ascertain which PA enzymes and PA inhibitors determine the level of secreted PA activity. A plasminogen-dependent esterolytic assay was used, and two lines (U251 and U373) were found to secrete high levels of PA activity, while PA activity was undetectable in the conditioned media from the remaining two lines (U138 and LM). The PA produced by U251 and U373 resolved as single bands comigrating with high molecular weight urokinase (Mr 54,000) on casein-plasminogen zymography. Northern blot analysis demonstrated high levels of mRNA for urokinase-type PA (uPA) in U251 and U373, as well as a considerably lower level of uPA message in LM. U251 and U373 also contained mRNA for tissue-type PA (tPA), although secreted tPA activity was not demonstrated by zymography. The U138 line contained essentially undetectable levels of mRNA for either uPA or tPA. U138 was also unique in secreting PA inhibitor activity and contained high levels of mRNA for PA inhibitor 2, which was not seen in any other line. All cell lines contained PA inhibitor 1 mRNA, with substantially more expression in the U138 and LM lines than in U251 and U373. None of the lines secreted measureable anti-plasmin activity. We conclude that there is considerable heterogeneity among human glioma cells in expression of PA enzymes and PA inhibitors. The coordinated regulation of these proteins likely determines secreted PA activity and the resultant role of plasminogen activation in tumor implantation and invasion.
 ...
PMID:Expression of heterogeneous profiles of plasminogen activators and plasminogen activator inhibitors by human glioma lines. 237 61

To investigate the mechanisms by which cutaneous plasminogen activator (PA) may be regulated, we have tested cultured keratinocytes for the presence of PA inhibitors. Using biosynthetic labeling experiments with 35S-methionine in conjunction with specific antibody precipitation, we have shown that human keratinocytes in culture synthesized and secreted both PA inhibitor 1 and PA inhibitor 2. PA inhibitor 1 was present in conditioned media in the inactive form, but it could be detected with reverse phase autography. PA inhibitor 2 was detected by its ability to form complexes with 125I-uPA. Potential therapeutic relevance for cutaneous PA inhibitor 2 was suggested in skin organ culture experiments which demonstrated that purified PA inhibitor 2 from human placenta was able to prevent the acantholytic changes induced by pemphigus IgG.
 ...
PMID:Characterization of keratinocyte plasminogen activator inhibitors and demonstration of the prevention of pemphigus IgG-induced acantholysis by a purified plasminogen activator inhibitor. 246 56

Effects of extracellular matrices (ECM) and the plasminogen activator (PA) system on outgrowth of sheep inner cell masses (ICM) and trophectoderm in vitro were investigated. Experiment 1 evaluated the effects of plasminogen and ECM type on ICM and trophectodermal outgrowth, on glass Lab-Tek chamber slides coated with collagen IV, fibronectin, or laminin. ICM outgrowth areas were reduced (p < 0.05) by plasminogen and were greatest (p < 0.05) on fibronectin. Trophectodermal outgrowth was not supported in this system. Experiment 2 evaluated the effects of PA inhibitor-2 (PAI-2) or antiserum to urokinase-type PA (anti-uPA) on ICM outgrowth on fibronectin. Numbers of cells in the outgrowths were increased (p < 0.05) with PAI-2, and anti-uPA had no effect (p > 0.10). Experiment 3 evaluated the relationship between PA production and ECM type on ICM and trophectodermal outgrowth in microdrop cultures. PA production by ICM was greatest (p < 0.05) on fibronectin, but no differences (p > 0.10) were observed for trophectoderm. PA production was not correlated with ICM outgrowth areas (r = -0.12; p = 0.72) or numbers of cells in the ICM outgrowths (r = 0.09; p = 0.74) but was correlated with ICM areas (r = 0.75; p < 0.01) and numbers of cells in trophectodermal outgrowths (r = 0.57; p = 0.01). These results suggest that type of ECM, culture system, and alterations in the PA system influence cellular outgrowths by ICM and trophectoderm.
 ...
PMID:Evaluation of extracellular matrices and the plasminogen activator system in sheep inner cell mass and trophectodermal outgrowth in vitro. 763 51

Two experiments were conducted to evaluate factors affecting zona pellucida (ZP) solubility in bovine embryos during hatching in vitro. In Exp. 1, the relationship between blastocoelic expansion and ZP solubility was determined. Day-6 embryos (n = 42) with good or excellent quality grades were cultured (Cultured embryos), whereas embryos of fair quality (Not-cultured embryos) were immediately placed in .2% SDS, and the time required for complete dissolution of the ZP (ZPDT) was determined. For Cultured embryos, ZPDT was determined after 192 h of in vitro development. Zona pellucida dissolution time was greater (P < .05) in Not-cultured embryos than in Cultured embryos and negatively correlated (P < .01) with changes in embryonic surface area. In Exp. 2, the effects of suppressing plasminogen activator (PA) activity and blastocoelic expansion on hatching and ZP solubility were examined. Day-6 embryos (n = 99) were cultured in medium containing 0, 10, or 100 IU/mL of human PA inhibitor-2 (PAI-2) and incubated for 24 to 44 h in medium containing 0, .1, or .5 nM ouabain. Percentages of embryos hatching were not different (P > .05) among 0, 10, and 100 IU/mL of PAI-2; however, more (P < .05) embryos hatched after exposure to 0 and .1 nM ouabain than to .5 nM ouabain. Embryonic PA activity was suppressed (P < .05) by PAI-2, whereas exposure to ouabain did not affect (P > .05) PA activity. Mean ZPDT did not differ (P > .05) following culture in medium containing PAI-2 or exposure to ouabain.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effects of blastocoelic expansion and plasminogen activator activity on hatching and zona pellucida solubility in bovine embryos in vitro. 773 Jan 88

Cultured human mesangial cells (HMC) derived from normal kidneys have been shown to synthesize tissue-type plasminogen activator (t-PA) and excess amounts of PA inhibitor type 1 (PAI-1). Conflicting results have been obtained concerning the production of urokinase-type PA (u-PA) and efforts to show PA inhibitor 2 (PAI-2) met with failure. We evaluated the fibrinolytic profile of cultured HMC lines obtained from 12 patients with renal carcinoma and one cadaveric kidney donor. Subconfluent cells (third passage) were incubated overnight in serum-free medium. t-PA, u-PA, PAI-1 and PAI-2 antigens were assayed by ELISA methods and PA and PAI activities by amidolytic methods both in conditioned medium (CM) and cell extracts (CE). Besides PAI-1, PAI-2 antigen was detected in all but one HMC lines. At variance with the former, which was largely released in the culture medium, PAI-2 was mainly cell-associated. t-PA antigen was found in all but two cell lines while u-PA antigen was detected in relatively high concentrations in 8 cell lines. PA activity, identified as u-PA by functional and immunological criteria, was measured in CM of six of the eight u-PA producing cell lines, whereas PAI activity was undetectable or very low in CM of all cell lines, suggesting that PAI-1 was largely inactive. Functional assays of cell extracts demonstrated the presence of PA activity, again identified as u-PA, only in samples (five lines) containing u-PA antigen in excess over PAI-2. PAI activity was found instead in the extracts in which the inhibitor was higher than the activator (six lines) and was identified as PAI-2, as it inhibited u-PA but not single-chain t-PA and was neutralized by a polyclonal anti-PAI-2 antibody. The heterogeneous fibrinolytic pattern of HMC lines was confirmed by mRNA analysis of three representative lines. Results were similar when HMC lines at passage five were used, except that the u-PA content was significantly reduced both in CM and CE. These findings indicate that the fibrinolytic profile of cultured HMC is more complex than previously reported. The production of large amounts of PAI-2 may represent an additional control mechanism of proteinase activity.
 ...
PMID:Cultured human mesangial cells produce both type 1 and type 2 plasminogen activator inhibitors. 877 30

In patients with colorectal cancer, profound alterations of the plasminogen activator system have been described at the tumor level, but conflicting results have been obtained for fibrinolytic parameters in plasma. Components of the fibrinolytic system, including tissue-type and urokinase-type plasminogen activators and their inhibitors type 1 and 2, were measured in tissue and/or plasma from 41 patients with colorectal cancer and in 40 controls. Procoagulant activity of freshly isolated mononuclear cells (basal activity) and the procoagulant activity and fibrinolytic proteins produced by the cells after incubation for 18 h without exogenous stimulation were also evaluated. Malignant tissue extracts had significantly higher levels of urokinase-type plasminogen activator and plasminogen activator inhibitor-1, but lower levels of tissue-type plasminogen activator than normal mucosa. Plasminogen activator inhibitor-1 alone was higher in advanced (Dukes' stages C + D) than limited (B) tumors. Plasminogen activator inhibitor-2 was not different in malignant tissue and normal mucosa. Plasma levels of plasminogen activator inhibitor-1 antigen were significantly increased in cancer patients compared with controls, but there were no differences in tissue-type and urokinase-type plasminogen activator, in plasminogen activator inhibitor-2, and D-dimer levels. Intra-patient analysis revealed no significant correlation between tumor and plasma levels of plasminogen activators or type 1 inhibitor. Tissue-type plasminogen activator, but not the urokinase type or inhibitor type 1, was higher in venous than in arterial blood collected at the tumor site during surgery. Basal procoagulant activity of mononuclear cells and the procoagulant activity and inhibitor type-2 produced by the cells after short-term culture were comparable in patients and controls. These findings indicate that, at least in our patients with colorectal cancer, the profound changes occurring at tumor level are barely detectable in the blood. Thus, the clinical relevance of plasma fibrinolytic parameters, especially urokinase-type plasminogen activator antigen, as tumor markers in colorectal cancer remains to be established.
 ...
PMID:Blood and tissue fibrinolytic profiles in patients with colorectal carcinoma. 878 47

The recent structure determination of the catalytic domain of tissue-type plasminogen activator (tPA) suggested residue Arg174 could play a role in P3/P4 substrate specificity. Six synthetic chromogenic tPA substrates of the type R-Xaa-Gly-Arg-p-nitroanilide, in which R is an N-terminal protection group, were synthesized to test this property. Although changing the residue Xaa (in its L or D form) at position P3 from the hydrophobic Phe to an acidic residue, Asp or Glu, gave no improvement in catalytic efficiency, comparative analysis of the substrates indicated a preference for an acidic substituent occupying the S3 site when the S4 site contains a hydrophobic or basic moiety. The 2.9 A structure determination of the catalytic domain of human tPA in complex with the bis-benzamidine inhibitor 2, 7-bis-(4-amidinobenzylidene)-cycloheptan-1-one reveals a three-site interaction, salt bridge formation of the proximal amidino group of the inhibitor with Asp189 in the primary specificity pocket, extensive hydrophobic surface burial, and a weak electrostatic interaction between the distal amidino group of the inhibitor and two carbonyl oxygens of the protein. The latter position was previously occupied by the guanidino group of Arg174, which swings out to form the western edge of the S3 pocket. These data suggest that the side chain of Arg174 is flexible, and does not play a major role in the S4 specificity of tPA. On the other hand, this residue would modulate S3 specificity, and may be exploited to fine tune the specificity and selectivity of tPA substrates and inhibitors.
 ...
PMID:Structural mapping of the active site specificity determinants of human tissue-type plasminogen activator. Implications for the design of low molecular weight substrates and inhibitors. 926 99

Plasminogen activator inhibitor-2 (PAI-2), a member of the serpin gene family, is thought to serve as a primary regulator of plasminogen activation in the extravascular compartment. High levels of PAI-2 are found in keratinocytes, monocytes, and the human trophoblast, the latter suggesting a role in placental maintenance or embryo development. The primarily intracellular distribution of PAI-2 also may indicate a unique regulatory role in a protease-dependent cellular process such as apoptosis. To examine the potential functions of PAI-2 in vivo, we generated PAI-2-deficient mice by gene targeting in embryonic stem cells. Homozygous PAI-2-deficient mice exhibited normal development, survival, and fertility and were also indistinguishable from normal controls in response to a bacterial infectious challenge or endotoxin infusion. No differences in monocyte recruitment into the peritoneum were observed after thioglycollate injection. Epidermal wound healing was equivalent among PAI-2 -/- null and control mice. Finally, crossing PAI-2 -/- with PAI-1 -/- mice to generate animals deficient in both plasminogen activator inhibitors failed to uncover an overlap in function between these two related proteins.
 ...
PMID:The plasminogen activator inhibitor-2 gene is not required for normal murine development or survival. 989 94

Retinoids have been shown to modulate several functions of mononuclear phagocytes. We investigated the in vitro effect of all-trans-retinoic acid (ATRA) on the production of two major fibrinolytic components, urokinase-type plasminogen activator (u-PA) and PA inhibitor 2 (PAI-2), by human blood mononuclear cells (MNC). ATRA caused a dose-dependent (range 0.01-10 microM) accumulation of PAI-2 antigen and activity into the cell culture medium, with a maximal increase (about 5-fold over control) at a concentration of 1-10 microM. Similarly, a dose-dependent increase in PAI-2 antigen was observed in cell extracts upon ATRA stimulation. Northern blot analysis showed a parallel increase in the amount of PAI-2 mRNA in ATRA-treated cells. Time-course experiments with 1 microM ATRA showed enhanced PAI-2 mRNA expression as early as 2 h, reaching a maximum at 4-6 h and then declining at 18-24 h, and a time-dependent increase in PAI-2 antigen in the cell culture medium. At variance with PAI-2, u-PA was not influenced by the drug. To establish whether ATRA-induced changes influenced the fibrinolytic process, we evaluated the effect of MNC stimulated with ATRA on u-PA-induced degradation of diluted plasma clots. ATRA-treated cells markedly inhibited clot lysis induced by low concentrations of u-PA. The effect was due to enhanced extracellular PAI-2 accumulation since it was observed with conditioned medium from ATRA-treated cells; it was abolished by the addition of neutralizing anti-PAI-2 antibodies and was negligible when single-chain t-PA was used instead of u-PA. Since monocyte/macrophage-mediated, plasminogen-dependent extracellular proteolysis has been proposed as an important mechanism of tissue damage in several inflammatory states, our findings might contribute to better explain the anti-inflammatory properties of retinoids.
 ...
PMID:Retinoic acid stimulates plasminogen activator inhibitor 2 production by blood mononuclear cells and inhibits urokinase-induced extracellular proteolysis. 1058 14


1 2 Next >>