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  • 1
    Electronic Resource
    Electronic Resource
    HORMONAL REGULATION OF MEMBRANE PHENOTYPE IN HEPATOMA CELLS (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 349 (1980), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1980.tb29527.x
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  • 2
    Electronic Resource
    Electronic Resource
    Dexamethasone-induced adhesion in hepatoma cells: the role of plasminogen activator (1979)
    [s.l.] : Nature Publishing Group
    Nature 277 (1979), S. 312-313 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Wild-type HTC cells were incubated overnight m radioactive medium containing 3% plasmmogen-depleted fetal calf serum in the presence () or absence (O) of 0 1 ,? dexamethasone, or in the same medium reconstituted with 4 8 jxg ml"1 plasminogen in the presence (A) or absence (?) of 0 1 ,? ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/277312a0
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  • 3
    Electronic Resource
    Electronic Resource
    Hormonal regulation of plasminogen activator in rat hepatoma cells (1983)
    Springer
    Molecular and cellular biochemistry 53-54 (1983), S. 11-21 
    Details
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Plasminogen activators are membrane-associated, arginine-specific serine proteases which convert the inactive plasma zymogen plasminogen to plasmin, an active, broad-spectrum serine protease. Plasmin, the major fibrinolytic enzyme in blood, also participates in a number of physiologic functions involving protein processing and tissue remodelling, and may play an important role in tumor invasion and metastasis. In HTC rat hepatoma cells in. tissue culture, glucocorticoids rapidly decrease plasminogen activator (PA) activity. We have shown that this decrease is mediated by induction of a soluble inhibitor of PA activity rather than modulation of the amount of PA. The hormonally-induced inhibitor is a cellular product which specifically inhibits PA but not plasmin. We have isolated variant lines of HTC cells which are selectively resistant to the glucocorticoid inhibition of PA but retain other glucocorticoid responses. These variants lack the hormonally-induced inhibitor; PA from these variants is fully sensitive to inhibition by inhibitor from steroid-treated wild-type cells. Cyclic nucleotides dramatically stimulate PA activity in HTC cells in a time- and concentration-dependent manner. Paradoxically, glucocorticoids further enhance this stimulation. Thus glucocorticoids exert two separate and opposite effects on PA activity. The availability of glucocorticoid-resistant variant cell lines, together with the unique regulatory interactions of steroids and cyclic nucleotides, make HTC cells a useful experimental system in which to study the multihormonal regulation of plasminogen activator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225243
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation of rat hepatoma cell variants selectively resistant to dexamethasone inhibition of plasminogen activator (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 99 (1979), S. 333-341 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Glucocorticoids induce several phenotypic changes in rat hepatoma cells in tissue culture, including the inhibition of plasminogen activator activity. Variant cell lines resistant to dexamethasone inhibtion of plasminogen activator activity have been isolated using an agar-fibrin overlay technique to identify colonies with fibrinolytic (plasminogen activator) activity. The variants are resistant to concentrations of dexamethasone 1,000 times that necessary to completely inhibit plasminogen activator activity in wild-type cells. The variant phenotype has been inherited in a stable manner for more than 300 generations in continuous culture in the absence of dexamethasone. These variants are unique in that the resistance is not secondary to defective or absent glucocorticoid receptors but is due to a lesion specific for regulation of plasminogen activator. Fluctuation analyses support the hypothesis that resistance to dexamethasone arises randomly and is not induced by dexamethasone. Because HTC cells are heteroploid and karyotypically highly variable, variants are thought to arise primarily by chromosomal segregation events. These variants provide a valuable tool for studying the mechanism of hormonal regulation of plasminogen activator as well as the role of proteases in hormonal regulation of membrane functions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040990308
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  • 5
    Electronic Resource
    Electronic Resource
    p52 induction by cytochalasin D in rat kidney fibroblasts: Homologies between p52 and plasminogen activator inhibitor type-1 (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 143 (1990), S. 321-329 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normal rat kidney (NRK) fibroblasts respond to the cell shape-modulating chemical agent cytochalasin D (CD) with augmented synthesis of the 52-kDa substrate-associated protein p52. p52 is a complex glycoprotein, existing as 12 different isoforms, which include a 43-kDa “core” protein (p43), four 50-kDa species (p50-0,1,2,3), and at least seven distinct pl variants of the mature 52-kDa protein. A threshold of 2-4 μM CD was found to be necessary to augment p52 deposition into both the secreted protein- and saponin-resistant cytomatrix (SAP) fractions of NRK cells. This concentration of CD was also necessary to initiate significant cell rounding. Augmented p52 production in CD-treated NRK (NRK/CD) cells provided a means to assess the identity of this protein. p52 was found to be identical to rat plasminogen activator inhibitor type-1 (rPAI-1) and to PAI-1-like proteins of other species by comparative immunoprecipitation, 2-D electrophoretic profile, V8 protease digest mapping, and subcellular fractionation criteria. Quantitation of rPAI-1 cytoplasmic mRNA abundance, using the rPAI-1 cDNA probe pSS1-3, revealed an induction of rPAI-1 mRNA in NRK/CD cells which paralleled the increased protein production. CD-augmented p52(rPAI-1) synthesis and SAP deposition was blocked by actinomycin D, implicating a need for RNA synthesis during the period of CD exposure to effect induction. Augmentation of p52 expression in NRK/CD fibroblasts, thus, appears to involve both cell shape-associated metabolic processes and concomitant RNA synthesis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041430216
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  • 6
    Electronic Resource
    Electronic Resource
    Transforming growth factor beta inhibits plasminogen activator (PA) activity and stimulates production of urokinase-type PA, PA inhibitor-1 mRNA, and protein in rat osteoblast-like cells (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 149 (1991), S. 34-43 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transforming growth factor(β)(TGFβ) treatment of rat osteoblast-rich calvarial cells or of the clonal osteogenic sarcoma cells, UMR 106-01, resulted in dosedependent inhibition of plasminogen activator (PA) activity, and increased production of 3.2 kb mRNA and protein for PA inhibitor-1 (PAI-1). Although tissue-type PA(tPA) protein was not measured, TGF(β)did not influence production of mRNA for tPA. Production of 2.3 kb mRNA for urokinase-type PA (uPA) was also increased by TGF(β)in a dose-dependent manner. The effects of TGFβ on synthesis of mRNA for PAI-1 and uPA were maintained when protein synthesis was inhibited, and were abolished by inhibition of RNA synthesis. Although uPA had not been detected previously as a product of rat osteoblasts, treatment of lysates of osteoblast-like cells with plasmin yielded a band of PA activity on reverse fibrin autography, corresponding to a low Mr form of uPA. Untreated conditioned media from normal osteoblasts or UMR 106-01 cells contained no significant TGFβ activity, but activity could be detected in acidified medium. Treatment of conditioned media with plasmin resulted in activation of approximately 50% of the TGFβ detectable in acidified media. The results identify several effects of TGFβ on the PA-PA inhibitor system in osteoblasts. Net regulation of tPA activity through the stimulatory actions of several calciotropic hormones and the promotion of PAI-1 formation by TGFβ could determine the amount of osteoblast-derived TGFβ activated locally in bone. Stimulation of osteoblast production of mRNA for uPA could reflect effects on the synthesis of sc-uPA, a precursor for the active form of the enzyme.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041490106
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  • 7
    Electronic Resource
    Electronic Resource
    Plasminogen activator regulation in osteoblasts: Parathyroid hormone inhibition of type-1 plasminogen activator inhibitor and its mRNA (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 152 (1992), S. 346-355 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to determine the mechanism by which parathyroid hormone (PTH) stimulates plasminogen activator (PA) activity in rat osteoblasts, we investigated the effect of human PTH(1-34) [hPTH(1-34)] on the synthesis of mRNAs for tissue-type PA (tPA), urokinase-type PA (uPA), and PA inhibitor-1 (PAI-1), and on release of PA activity and PAI-1 protein in both normal rat calvarial osteoblasts and UMR 106-01 osteogenic sarcoma cells. hPTH(1-34) (0.25-25 nM) decreased PAI-1 mRNA and protein, and increased PA activity in both cell types in a dose-dependent manner with ED50 of about 1 nM for both responses. Forskolin and isobutylmethylxanthine also stimulated PA activity and decreased PAI-1 protein and mRNA in both cell types. hPTH(1-34) did not show any consistent effect on tPA and uPA mRNA in calvarial osteoblasts, but a modest (two-fold) increase of both mRNAs was observed in UMR 106-01 cells treated with 25 nM hPTH(1-34). However, when protein synthesis was inhibited with 100 μM cycloheximide, the increase of tPA and uPA mRNA by hPTH(1-34) was enhanced in UMR 106-01 cells and became evident in calvarial osteoblasts. Fibrin autography also revealed that hPTH(1-34) increases tPA and uPA activity, especially after cycloheximide treatment in UMR 106-01 cells. These results strongly suggest that PTH increases PA activity predominantly by decreasing PAI-1 protein production through a cyclic adenosine monophosphate (cAMP)-dependent mechanism in rat osteoblasts. The reduction of PAI-1 protein by PTH results in enhanced action of both tPA and uPA, and would contribute to the specific roles of these PAs in bone. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041520216
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  • 8
    Electronic Resource
    Electronic Resource
    Hormonal regulation of membrane phenotype (1977)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 6 (1977), S. 325-331 
    Details
    ISSN: 0091-7419
    Keywords: plasminogen activator ; hepatoma cells ; transformed membrane phenotype ; glucocorticoid-resistant variants ; glucocorticoids ; amino acid transport ; hormonal regulation ; glucocorticoid regulation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Incubation of rat hepatoma cells (HTC) in tissue culture with glucocorticoids alters several membrane properties characteristic of transformed cells, without affecting the growth rate of these cells. Variant cell lines resistant to dexamethasone inhibition of plasminogen activator production have been isolated using an agar-fibrin overlay technique to detect plasminogen activator production by individual colonies of HTC cells. The resistance to dexamethasone is not secondary to abnormal or absent glucocorticoid receptors, but due to a lesion in a later step in hormone action specific for plasminogen activator. These variants should prove useful for the study of the mechanism of steroid action as well as for the analysis of the role of proteases in the hormonal regulation of membrane function.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400060305
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