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)

Variants of tissue-type plasminogen activator (t-PA) were constructed with selected cysteines replaced by alanine to evaluate the role of an unpaired cysteine, which has been presumed to be in the growth factor module. C75A, C83A, C84A and CC83-84AA variants of t-PA were expressed transiently in human embryonic kidney cells. The biochemical properties of these variants provided experimental evidence to identify the unpaired cysteine in t-PA. Assays of amidolytic activity, plasminogen activation (in the presence or absence of fibrinogen or fibrin), plasma clot lysis, fibrin binding, clearance in mice, and interaction with a panel of monoclonal antibodies were performed as the basis for comparing these variants with wild-type t-PA. In all assays, C83A t-PA was biochemically equivalent to wild-type t-PA. C75A t-PA, C84A t-PA and CC83-84AA t-PA variants exhibited reduced activities in a variety of functional assays. These variants displayed two-to threefold lower activity in fibrinogen or fibrin stimulated plasminogen activation, and fivefold reduced plasma clot lysis activity compared with that of wild-type t-PA. The affinity of C75A t-PA and C84A t-PA for fibrin was decreased more than two orders of magnitude compared with C83A t-PA or wild-type t-PA. Plasma clearance of C75A t-PA and C84A t-PA was reduced 2-fold in mice. The C75A, C84A and CC83-84AA variants displayed significantly decreased reactivity with anti-tPA monoclonal antibodies specific for finger/growth factor domain epitopes. These data are consistent with a disulfide linkage of Cys75 with Cys84 and that Cys83 exists as an unpaired sulfhydryl. The significance of the unpaired cysteine is as yet undetermined since C83A t-PA and wild-type t-PA are functionally equivalent.
 ...
PMID:Locating the unpaired cysteine of tissue-type plasminogen activator. 873 95

The plasminogen activators, tissue type and urokinase type (tPA and uPA, respectively), have been identified in various malignancies and have been implicated in both local growth and metastatic spread. To characterize plasminogen activator expression more fully in human basal cell carcinoma, the localization of uPA and tPA mRNAs was evaluated by in situ hybridization. Nodular basal cell carcinomas demonstrated uPA expression in most cases, whereas the non-nodular subtypes were negative. Message for uPA was identified within tumour islands (11/12 cases), scattered fibroblast-like stromal cells (6/12 cases), and the basal layer of the overlying epidermis (10/12 cases). In addition, signal for uPA was elevated and pronounced in areas where the epidermis merged into invasive basal cell carcinoma in the superficial papillary dermis in some cases. Message for uPA was often associated with ulceration or erosion of the overlying epithelium. Expression of tPA was noted in the epidermis (3/12 cases) and in tumour cells (4/12 cases), but tended to be focal and sparse. These results suggest that complex interactions involving uPA expression occur between the tumour, the stroma, and the overlying epidermis. Both the stroma and the epidermis may contribute to local spread of the tumour through production of uPA and consequent plasmin-mediated activation of collagenases and metalloproteinases.
 ...
PMID:Expression of plasminogen activators in basal cell carcinoma. 877 34

The immunogenicity of a tissue-type plasminogen activator analog, mt-PA6, consisting of the second kringle and protease domains, was compared to that of the native-sequence protein (nt-PA) in rhesus monkeys. Antibody responses were compared in groups of eight monkeys that were treated by i.v. injection twice, 1 month apart, using doses and regimens chosen to mimic therapy (0.5 mg/kg mt-PA6 bolus, 1.25 mg/kg nt-PA bolus + infusion). An additional group was treated with a 0.5 mg/kg nt-PA bolus. A single positive response was obtained in a monkey treated with 0.5 mg/kg nt-PA after the primary injection. Following the secondary injection, responses were obtained in 1/8, 3/8, and 6/8 monkeys treated with mt-PA6, nt-PA as a bolus, or nt-PA as a bolus + infusion, respectively. Several monkeys were selected to determine whether circulating tPA antibody altered the pharmacokinetics of mt-PA6. Clearance was found to decrease without affecting peak blood levels as antibody concentrations increased from 0.02 to 100 micrograms/ml. In contrast, the peak blood level was reduced by 99% at an antibody concentration of 152 micrograms/ml in a monkey that had been exposed to mt-PA6 in adjuvant 14 months previously. Further, only the serum from this and three other hyperimmunized monkeys inhibited the enzymatic activity of tPA in vitro. It is concluded that mt-PA6 is not more immunogenic than nt-PA in rhesus, and that low levels of antibody are more likely to influence the pharmacokinetic properties of tPA than to inhibit its enzymatic activity. It is unlikely that mt-PA6 would present a serious immunogenic risk in humans.
 ...
PMID:Immunogenicity of tissue plasminogen activators in rhesus monkeys: antibody formation and effects on blood level and enzymatic activity. 881 72

Human recombinant tissue-type plasminogen activator (rtPA), administered intraperitoneally, may promote intra-abdominal fibrinolysis in peritonitis, thereby preventing adhesion and abscess formation. The pharmacokinetics of a single intraperitoneal dose of 0.5 or 2.0 mg/ml human rtPA were assessed in rats with fecal peritonitis and related to their endogenous tPA and plasminogen activator inhibitor (PAI) activity. Endogenous PAI activity was strongly elevated both in peritoneal fluid and in plasma, whereas tPA activity was only slightly increased in the peritoneal fluid. Both doses of rtPA significantly enhanced fibrinolytic activity of the peritoneal fluid up to 24 h in a dose-dependent manner. However, tPA activity was lower than calculated from the tPA antigen levels and the specific activity of rtPA in the fluid of rats with peritonitis. Plasma tPA activity was low at both doses. A single dose of 0.5 or 2.0 mg/ml rtPA can raise fibrinolytic activity in the abdominal cavity up to 24 h. High endogenous peritoneal PAI levels may adversely effect intra-abdominal use of human rtPA in peritonitis.
 ...
PMID:Pharmacokinetics of human recombinant tissue-type plasminogen activator, administered intra-abdominally, in a rat peritonitis model. 881 53

While several studies have documented the presence of plasminogen activator (PA) activity in hen ovarian follicle granulosa and theca tissues, to date it has not been possible to conclusively distinguish between the urokinase (u) and the tissue-type (t) form of the enzyme; this inability is due, in part, to lack of the cloned or characterized chicken tPA gene or gene product. Thus, the present studies were conducted to identify a partial cDNA for chicken tPA and subsequently to evaluate expression of uPA and tPA mRNA in granulosa and theca tissues in vivo and in vitro. Urokinase PA and mRNA levels were highest in prehierarchical-follicle granulosa (3- to 5- and 6- to 8-mm follicles) and theca (6- to 8-mm follicles) tissue compared to hierarchical (9-12 mm through largest preovulatory) follicles. In vitro treatment with a phorbol ester (phorbol 12-myristate, 13-acetate), but not a cAMP analogue (8-bromo-cAMP), significantly increased uPA mRNA levels in both granulosa and theca tissue from the largest and second-largest preovulatory follicles. Of special interest was the finding that levels of uPA mRNA were 10.9-fold higher in atretic compared to morphologically normal 3- to 5-mm follicles. Moreover, 4- to 8-mm-follicle granulosa cells, which spontaneously undergo apoptosis in vitro, demonstrated a rapid increase in uPA mRNA levels after 1 h of incubation (prior to the detection of oligonucleosome formation) while levels in preovulatory-follicle granulosa cells, which do not undergo spontaneous apoptosis, were not altered after 18 h of incubation. By contrast, while tPA mRNA can be identified in granulosa and theca tissues from prehierarchical and preovulatory follicles following polymerase chain reaction amplification, constitutively expressed levels of the transcript were too low to reliably measure by Northern blot analysis. These data indicate that while the chicken expresses a tPA gene that is homologous to the mammalian tPA, uPA is the predominant PA expressed in the hen ovary. In addition, the higher levels of uPA mRNA found in granulosa cells actively undergoing apoptosis and in follicles most susceptible to atresia (4-8 mm) suggest a role for this protease in mediating processes both during the early stages of programmed cell death and in the later stages of follicle atresia and resorption.
 ...
PMID:Expression of avian urokinase and tissue-type plasminogen activator messenger ribonucleic acid during follicle development and atresia. 904

A patient, aged 34, with a relapse of Behcet's disease (BD) showed laboratory features of enhanced coagulation activation without any symptoms of arterial or venous thrombosis. Elevated levels of thrombin-antithrombin III complexes (TAT), prothrombin fragments 1 + 2 (F1 + 2), associated with impairement of fibrinolysis were found. Total fibrinolytic activity, measured on fibrin plates, plasma concentration of tissue-type plasminogen activator (tPA:Ag) and plasmin-alpha 2-antiplasmin complexes (PAP) were low, whereas plasminogen activator inhibitor 1 concentration (PAI-1:Ag) was elevated in comparison with normal values. There intravenous 500 mg doses of cyclophosphamide, given on day 0, 7 and 50, resulted in a marked clinical improvement. This was accompanied by the normalization of augmented thrombin generation and increased fibrinolytic activity. This is the first report to show prothrombotic tendency in a relapse of Behcet disease and beneficial effect of cyclophosphamide therapy on haemostatic abnormalities. A degree of activation of coagulative and fibrinolytic system seems to be of importance in the pathogenesis of Behcet's disease, and monitoring of hemostatic parameters could be helpful in clinical assessment.
 ...
PMID:[Subclinical pro-thrombotic state in a relapse of Behcet's disease--case report]. 912 17

The plasminogen activator (PA)-plasmin proteolytic system has recently received considerable attention because of its participation in a wide variety of biological activities and in pathological conditions involving tissue destruction. Excessive mechanical stress such as occlusal trauma is associated with alveolar bone loss in severe periodontitis. Therefore, mechanical stress may involve degradation of the extracellular matrix by occlusal trauma through activation of the PA-plasmin proteolytic system. We examined the effects of mechanical stress on PA activity, gene expressions of tissue type (t) PA, urokinase type (u) PA and PA inhibitor-1 (PAI-1) in human PDL cells. Human PDL cells were cultured on flexible-bottomed culture plates and placed on a Flexercell Strain Unit. The cells were flexed at 6 cycles (5 s strain, 5 s relaxation) at 9% and 18% elongation for 5 d. Application of tension-force induced significantly higher PA activity in stressed PDL cells than in non-stressed controls, and did so in a time- and magnitude-dependent manner (p < 0.001, ANOVA). Western-blot analysis revealed that the high level of activity was due to tPA and not uPA. Gene expression of tPA mRNA in stressed PDL cells, as examined by RT-PCR, increased on d 5. These findings suggest that tPA may be involved in periodontal metabolism in response to mechanical stress.
 ...
PMID:Effect of tension-force on plasminogen activator activity from human periodontal ligament cells. 913 97

Erythrina variegata trypsin inhibitors designated ETIa and ETIb belong to the Kunitz family trypsin inhibitor, but ETIa is unique in its ability to inhibit tissue-type plasminogen activator, while ETIb is not. The cDNA clone encoding ETIb was isolated from the seed cDNA library constructed in the lambda phage lambda gt11. The ETIb cDNA insert consists of 765 bp, including an open reading frame of 606 pb from ATG to TGA codons. The deduced amino acid sequence consists of 202 amino acids, having the signal peptides of 22 amino acids in the N-terminus and 2 amino acids in C-terminus. The cDNA fragment encoding the mature form of ETIb was introduced into an expression vector, pET-22b, and expressed in Escherichia coli BL21 (ED3) in a functional form. Furthermore, the ETIb mutant bP61R/F62L, in which Pro61 and Phe62 in ETIb were changed to the corresponding amino acid residues Arg and Leu, respectively, as in ETIa, was constructed, and its inhibitory potency toward tPA was assayed. This mutant showed significant tPA inhibitory activity, albeit less than ETIa. The result demonstrates that the Arg61 and Leu62 residues in ETIa are important in inhibiting tPA, and also suggest that beside these two residues, the other amino acid(s) or other structural element may be involved in interaction of ETIa with tPA.
 ...
PMID:Cloning, expression, and mutagenesis of trypsin inhibitor ETIb from Erythrina variegata seeds. 921 69

Induction of in vitro angiogenesis and upregulation of urokinase- and tissue type-plasminogen activator (uPA, tPA) expression are two hallmarks of vascular endothelial growth factor (VEGF) activity on cultured endothelial cells. We report here that neutralizing antibodies to basic fibroblast growth factor (bFGF) inhibit VEGF-induced in vitro angiogenesis in bovine microvascular endothelial (BME) cells. Analysis of VEGF receptor-2 (VEGFR-2) expression revealed no alteration in VEGFR-2 mRNA or total protein in anti-bFGF antibody-treated BME or bovine aortic endothelial (BAE) cells. Ethidium bromide/agarose gel electrophoresis on the cytosolic fraction of BME cells revealed a basal level of fragmented DNA that was increased by anti-bFGF antibodies to an extent not exceeding that observed in parallel cultures incubated with concentrations of transforming growth factor-ss1 that increase VEGF-induced in vitro angiogenesis. In both BME and BAE cells, antibodies to bFGF also decreased basal levels of cell-associated uPA activity, and completely blocked the VEGF-mediated increase in uPA and tPA expression observed in parallel cultures incubated with VEGF alone. In contrast, PA inhibitor-1 expression was strongly upregulated in BME and BAE cells incubated with antibodies to bFGF, either alone or in combination with VEGF. These findings demonstrate that: (1) VEGF-induced in vitro angiogenesis and PA expression are dependent on endogenous bFGF, (2) that this phenomenon is not mediated by a decrease in VEGFR-2 expression and that apoptosis does not necessarily correlate with inhibition of invasion, and (3) that inhibition of endogenous bFGF in VEGF-treated cells results in a net antiproteolytic (and possibly also anti-adherent) effect, which could account in part for the inhibitory effect of the anti-bFGF antibodies. These findings point to a novel and unsuspected role for endogenous bFGF in regulating VEGF-induced in vitro angiogenesis.
 ...
PMID:Vascular endothelial growth factor-induced in vitro angiogenesis and plasminogen activator expression are dependent on endogenous basic fibroblast growth factor. 937 78

Epididymis is a site of sperm maturation and storage. Limited and directed-proteolysis regulated by plasminogen activator (PA), plasminogen activator inhibitor type-1 (PAI-1) and other related factors may play an essential role in these processes. Our previous studies have demonstrated that rat epididymis expressed luteinizing hormone receptor (LHR), tissue type (t) and urokinase type (u)PA, mRNAs, and tPA activity was stimulated in vitro by human chorionic gonoadotrophin (HCG). In the present study we further examined localization of mRNAs for tPA, uPA, LHR, androgen receptor (AR), as well as inhibin subunits alpha, betaA and betaB in rhesus monkey epididymis. Using in-situ hybridization with digoxygenin-labelled cRNA probes, we have demonstrated that tPA and PAI-1 mRNAs were localized in epithelial cells of adult monkey epididymis. uPA mRNA was localized in the same areas, but to a much smaller extent. tPA, uPA and PAI-1 mRNAs were greatly expressed in the caput and corpus of adult epididymis than in other regions. In-vitro experiments showed that both tPA and uPA activities in epididymal cells were dramatically stimulated by HCG, but not by follicle stimulating hormone (FSH). LHR (but not FSH receptor) and AR mRNAs were localized in the epithelial cells of the epididymis. However, LHR mRNA was detected in both adult and immature infant monkeys, whereas AR was found only in the adult. Inhibin alpha, betaA and betaB mRNAs were also detected in this organ, betaA mRNA being more strongly expressed in the caput than in other regions of the epididymis. We suggest that LH and androgen may be the key hormones in coordination with the PA-PAI-1 system in regulating epididymal differentiation and sperm maturation.
 ...
PMID:Localization of plasminogen activator and inhibitor, LH and androgen receptors and inhibin subunits in monkey epididymis. 943 19


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>