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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human tissue-type plasminogen activator gene (t-PA) is induced by the phorbol ester, phorbol 12-myristate 13-acetate (PMA), in HeLa cells. Previous studies in transfected HeLa cells identified two cis-acting regulatory elements within the t-PA gene promoter responsible for both constitutive and PMA-inducible expression. One element differs from the consensus cAMP response element (CRE) by a single nucleotide substitution (referred to in this report as t-PACRE) and another which bears similarity to the AP-2 recognition sequence. In HT-1080 fibrosarcoma cells, t-PA mRNA levels are expressed at higher constitutive levels and are suppressed by PMA. Nuclear run-on transcription experiments indicate that PMA-mediated suppression of t-PA in these cells is associated with a decrease in t-PA gene template activity. We designed experiments to determine whether nuclear t-PACRE or AP-2-like binding proteins were differentially expressed in HeLa and HT-1080 cells and, accordingly, if these could be correlated with the opposite effect of PMA on t-PA expression. Band shift analyses indicated that the migration profiles of HeLa and HT-1080 nuclear proteins interacting with the AP-2-like site were indistinguishable; however, those produced with the t-PACRE binding site were qualitatively and quantitatively distinct. The distribution of t-PACRE binding proteins in these cells was investigated in a supershift assay using specific antibodies against members of the fos/jun and CRE-binding protein (CREB)/activating transcription factor (ATF) families. In HT-1080 cells, CREB-1 was the most prominent t-PACRE-binding activity detected and was greatly increased in cells treated with PMA. In contrast, CREB-1 activity was absent in HeLa cells, but antibodies specific for ATF-2 produced a marked supershifted complex which was unaffected by PMA treatment. Since CREB-1 can repress transcription of other target genes (including c-jun) via association with identical cis-acting CRE-like sequences, we suggest that the mechanism for the transcriptional down-regulation of t-PA by PMA in HT-1080 cells requires CREB-1 binding to the t-PACRE while ATF-2, by associating with the same site, plays a role in PMA-mediated induction of t-PA in HeLa cells.
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PMID:Differential binding of cAMP-responsive-element (CRE)-binding protein-1 and activating transcription factor-2 to a CRE-like element in the human tissue-type plasminogen activator (t-PA) gene promoter correlates with opposite regulation of t-PA by phorbol ester in HT-1080 and HeLa cells. 864 95

The gene encoding tissue-type plasminogen activator (t-PA) is an immediate response gene, downstream from CREB-1 and other constitutively expressed transcription factors, which is induced in the hippocampus during the late phase of long-term potentiation (L-LTP). Mice in which the t-PA gene has been ablated (t-PA-/-) showed no gross anatomical, electrophysiological, sensory, or motor abnormalities but manifest a selective reduction in L-LTP in hippocampal slices in both the Schaffer collateral-CA1 and mossy fiber-CA3 pathways. t-PA-/- mice also exhibit reduced potentiation by cAMP analogs and D1/D5 agonists. By contrast, hippocampal-dependent learning and memory were not affected in these mice, whereas performance was impaired on two-way active avoidance, a striatum-dependent task. These results provide genetic evidence that t-PA is a downstream effector gene important for L-LTP and show that modest impairment of L-LTP in CA1 and CA3 does not result in hippocampus-dependent behavioral phenotypes.
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PMID:Mice lacking the gene encoding tissue-type plasminogen activator show a selective interference with late-phase long-term potentiation in both Schaffer collateral and mossy fiber pathways. 871 Sep 34

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.
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PMID:Expression of avian urokinase and tissue-type plasminogen activator messenger ribonucleic acid during follicle development and atresia. 904

Tissue-type plasminogen activator (tPA) activates plasminogen to the active protease plasmin and is implicated in many biological processes that require extracellular proteolysis. In rat ovarian cells, gonadotropins induce the tPA gene by a cAMP-dependent pathway and this induction correlates with the time of follicular rupture. We have previously identified several promoter elements within the first 621 bp of the rat tPA promoter that are important for constitutive and cAMP-induced expression of the gene, including a cAMP responsive element (CRE), a nuclear factor 1 (NF1) element, a SP1-binding site and a G+C-rich box. In this report we have extended our study by analysing promoter constructs, ranging in size from 7.7 kb to 135 bp fused to the luciferase reporter gene. Transient transfection analysis of rat granulosa cells and human 293 cells, reveal that the proximal 268 bp of the promoter is enough to confer high basal and cAMP-induced expression of the gene. At position -162 to -172, between the previously identified CRE and NF1 sites, a novel TAAT-containing promoter element was identified. Mutational inactivation of the TAAT motif indicates that this element is important for both constitutive and cAMP-induced expression of the gene, and for the binding of a presumably novel nuclear factor that we have termed tPA promoter factor-1 (tPF-1).
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PMID:Characterisation of the rat tissue-type plasminogen activator gene promoter -- identification of a TAAT-containing promoter element. 934 17

Early growth response with respect to tissue-type plasminogen activator (tPA) and type-1 plasminogen activator inhibitor (PAI-1) gene expression was studied in rat hepatocytes in primary culture. The genes for tPA and PAI-1 could be categorized as a delayed early growth response (DER) gene and an immediate early growth response (IER) gene, respectively. The expression of tPA was much higher in growth-promoting than in static culture conditions (i.e., cultured at low density and/or on a collagen-coated dish), and that of PAI-1 was regulated in the opposite direction. Experiments using dibutyryl cAMP (dbcAMP) and H-89 showed that the cAMP/A-kinase system might be involved in the induction of the early growth response of tPA and in the augmentation of PAI-1 mRNA induction by dbcAMP. These fibrinolytic components, whose expression is closely associated with hepatocyte growth, may play important roles in pathophysiological events in the liver such as liver regeneration.
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PMID:Induction of tissue-type plasminogen activator (tPA) and type-1 plasminogen activator inhibitor (PAI-1) as early growth responses in rat hepatocytes in primary culture. 934 81

In the present study we report the isolation and characterization of a clonal Sertoli cell line (42GPA9) from sexually mature polyoma virus large T (PyLT) transgenic mice. The cells multiplied indefinitely and expressed large T antigen. The 42GPA9 cell line expressed biochemical features associated with normal Sertoli cells. Transferrin, sulfated glycoprotein-2, and the ligand of c-kit were detected by reverse transcription-polymerase chain reactions and Western blot analyses. Zymographic analysis indicated that the 42GPA9 cell line secreted tissue-type plasminogen activator. These cells also retained FSH receptors as suggested by their specific responsiveness to the gonadotropin (morphological and phagocytic changes, stimulation of cAMP production) and the detection of FSH receptor mRNAs. Another original aspect of the 42GPA9 cell line is its ability to form tight junctions at confluency as demonstrated by electron microscopic study and immunolocalization of the tight junction-associated protein zonula occludens 1. The 42GPA9 cell line, which has retained several important hallmarks of normal Sertoli cells, may prove useful for further studies on Sertoli cell behavior and on Sertoli-germ cell interactions in the mature testis.
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PMID:Characterization of a clonal Sertoli cell line using adult PyLT transgenic mice. 947 18

The effect of compounds increasing intracellular adenosine 3':5'-cyclic monophosphate [cAMP]i levels (prostacyclin, isoproterenol, forskolin, cholera toxin), and of the cAMP analogs 8-bromo-cAMP and dibutyryl-cAMP, on the regulated secretion (acute release) of tissue-type plasminogen activator (tPA) and von Willebrand factor (vWF) was studied in cultured human umbilical vein endothelial cells (HUVEC). Prostacyclin, isoproterenol and forskolin, which increased [cAMP]i in HUVEC, and the cell-permeant cAMP analog 8-bromo-cAMP induced dose- and time-dependent secretion of tPA and vWF. The extent of vWF and tPA release correlated with [cAMP]i, and was increased by the phosphodiesterase inhibitor isobutylmethylxanthine. In contrast to thrombin, the cAMP-elevating agents did not increase the intracellular calcium concentration [Ca2+]i in HUVEC. At submaximal concentrations, the effects of thrombin and prostacyclin were additive. Our results show that an increase in [cAMP]i resulted in regulated secretion (acute release) of tPA and vWF from HUVEC, without the concomitant increase in [Ca2+]i which is, in HUVEC, essential for thrombin-induced regulated secretion to occur. cAMP-induced secretion represents a novel mechanism for causing regulated secretion of tPA and vWF from endothelial cells.
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PMID:Adenosine 3':5'-cyclic monophosphate induces regulated secretion of tissue-type plasminogen activator and von Willebrand factor from cultured human endothelial cells. 956 4

Type-1 plasminogen activator-inhibitor (PAI-1) is a major physiologic inhibitor of plasminogen activation. Incubation of HTC rat hepatoma cells with the cyclic nucleotide analogue, 8-bromo-cAMP, causes a dramatic increase in tissue-type plasminogen activator activity secondary to a 90% decrease in PAI-1 mRNA. Although 8-bromo-cAMP causes a modest decrease in PAI-1 transcription, regulation is primarily the result of a 3-fold increase in the rate of PAI-1 mRNA degradation. To determine the cis-acting sequences required for cyclic nucleotide regulation, we have stably transfected HTC cells with chimeric genes containing sequences from the rat PAI-1 cDNA and the mouse beta-globin gene and examined the effect of cyclic nucleotides on the decay rate of these transcripts. The mRNA transcribed from the beta-globin gene is stable and not cyclic nucleotide-regulated, whereas the transcript from a construct containing the beta-globin coding region and the PAI-1 3'-untranslated region (UTR) is destabilized in the presence of 8-bromo-cAMP, suggesting that this response is mediated by sequences in the PAI-1 3'-UTR. Analyses by deletion of sequences from this chimeric construct indicate that, whereas more than one region of the PAI-1 3'-UTR can confer cyclic nucleotide responsiveness, the 3'-most 134-nucleotide sequence alone is sufficient to do so. Insertion of PAI-1 sequences within the beta-globin 3'-UTR confirms that the 3'-most 134 nucleotides of PAI-1 mRNA can confer cyclic nucleotide regulation of stability on a heterologous transcript, suggesting that this sequence may play a major role in hormonal regulation of PAI-1 mRNA stability.
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PMID:Cyclic nucleotide regulation of type-1 plasminogen activator-inhibitor mRNA stability in rat hepatoma cells. Identification of cis-acting sequences. 960 32

The plasminogen activators tPA and uPA, and their inhibitors, PAI-1 and PAI-2, have been associated with epithelial homeostasis and wound healing. In these studies, we investigate the effect of the steroid hormone hydrocortisone, a commonly used therapeutic modality for skin, on PAs/PAIs in serum- and plasminogen-free primary cultures of murine keratinocytes. SDS-PAGE fibrin zymography showed that addition of 1 microM hydrocortisone to cultures significantly reduced tPA fibrinolytic activity in both cell extracts and conditioned medium. uPA activity in conditioned medium was similarly inhibited. Cells were also cultured in the presence of dibutyryl cyclic AMP (dbcAMP). dbcAMP (5 mM) alone enhanced uPA and tPA fibrinolytic activity in conditioned medium, but this increase was diminished in the presence of 1 microM hydrocortisone. Immunoblots revealed a three- to fivefold induction of free PAI-1 by hydrocortisone which was partially blocked by dbcAMP. Northern blots showed that PAI-1 mRNA increased threefold 2 h after addition of hydrocortisone and remained elevated at least 8 h. In contrast, uPA and tPA mRNA were unchanged over the same time course. uPA, tPA, and PAI-1 mRNA increased in the presence of dbcAMP; levels remained elevated at least 8 h. HC suppressed the induction of uPA and tPA by dbcAMP. Studies directed at identifying plasminogen mRNA showed that in this culture system, keratinocytes produce no plasminogen mRNA either in the presence or in the absence of hydrocortisone or dbcAMP. Collectively, these results show that keratinocyte plasminogen activator activity is suppressed by hydrocortisone as a function of increased PAI-1 combined with an attenuation of PA induction by agents that increase intracellular cAMP. These results provide additional information to further define the mechanism by which glucocorticoids inhibit wound healing.
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PMID:Hydrocortisone regulates the dynamics of plasminogen activator and plasminogen activator inhibitor expression in cultured murine keratinocytes. 966 8

FSH is the main regulator of Sertoli cell function. Nevertheless, several other effectors such as catecholamines can also stimulate these cells through the adenylyl cyclase transduction pathway. However, the expression of beta adrenergic receptors in Sertoli cells is a subject of controversy. The aim of the present study was to determine if there are physiologically functional beta adrenergic receptors in Sertoli cells and to which subtype(s) they belong. In freshly isolated Sertoli cells, isoproterenol, a non selective beta-adrenergic agonist, was found to stimulate cAMP production and tissue-type plasminogen activator secretion. Specific transcripts for the beta1 and beta2, but not beta3, subtypes were detected by RT-PCR analysis. Beta2 transcripts were the form expressed predominantly in Sertoli cells. Binding experiments carried out on freshly isolated and on cytospined Sertoli cells indicated that in both conditions, [125I]iodocyanopindolol binding was inhibited by a non-selective and a 2 selective antagonist, whereas a beta1 selective antagonist had no effect. Scatchard analysis of beta2 specific inhibition revealed a dissociation constant of 0.3 nM and a receptor density of 14000 sites per cell. In freshly isolated Sertoli cells, we observed that cAMP and tissue-type plasminogen activator were stimulated by isoproterenol and a beta2 selective agonist, but not by beta1 or beta3 selective agonists. Accordingly, the isoproterenol-stimulated tissue-type plasminogen activator responses were abolished by the beta2 selective antagonist only. In cultured Sertoli cells, the trend was the same: tissue-type plasminogen activator and transferrin secretions were increased by isoproterenol and beta2 but not by beta1 or beta3 selective agonists. We conclude that freshly isolated Sertoli cells express beta2 adrenergic receptors which are functionally coupled to adenylyl cyclase and that these characteristics are preserved in cell culture. For the tested parameters, catecholamines and FSH effects were similar, but response magnitudes were systematically lower with beta agonists than with FSH. As norepinephrine is normally present in physiologically-relevant amounts in the interstitial fluid, it can be suspected to play a role in the regulation of Sertoli cell function.
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PMID:Beta2 adrenergic receptors mediate cAMP, tissue-type plasminogen activator and transferrin production in rat Sertoli cells. 978 5


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