scholarly journals Transforming growth factor β1 treatment of AKR-2B cells is coupled through a pertussis-toxin-sensitive G-protein(s)

1989 ◽  
Vol 261 (3) ◽  
pp. 879-886 ◽  
Author(s):  
P H Howe ◽  
E B Leof
Keyword(s):  
Growth Factor ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Cellular Proliferation ◽  
Transforming Growth Factor ◽  
Protein S ◽  
Dependent Manner ◽  
Guanine Nucleotide ◽  
Gtpase Activity ◽  
Tgf Beta

Transforming growth factor beta (TGF beta 1) is a potent regulator of DNA synthesis and cellular proliferation. In this study, we investigated whether the growth stimulatory signal of TGF beta 1 is transduced intracellularly by guanine nucleotide regulatory proteins (G-proteins). In plasma membranes from AKR-2B cells, TGF beta 1 increased binding of the radiolabelled, non-hydrolysable GTP analogue, guanosine 5′-[gamma-[35S]thio]triphosphate (GTP[35S]), in a dose-dependent manner. Maximal effects occurred between 0.4 and 1.0 nM-TGF beta 1. Specific binding of GTP[35S] occurred with a Kd of 3.2 x 10(-8) M which was not affected by addition of TGF beta 1. Instead, TGF beta 1 increased the number of available binding sites for GTP[35S] from 16.2 +/- 1.2 to 21.6 +/- 2.1 pmol/mg of protein. GTP[35S] binding was both nucleotide- and growth-factor-specific. Only guanine nucleotides were able to compete for binding, and of the growth factors tested (epidermal growth factor, platelet-derived growth factor, insulin, TGF beta 1 and TGF beta 2) only TGF beta 1 affected GTP[35S] binding. TGF beta 1 increased GTPase activity, as determined by the release of 32PO4(3-) from GTP gamma[32P], from 116 +/- 5.5 to 175 +/- 4.3 pmol/mg of protein following a 15 min incubation. Pretreatment of the membranes with pertussis toxin inhibited both TGF beta 1-stimulated binding of GTP[35S] as well as TGF beta 1-stimulated GTPase activity. These inhibitory actions of pertussis toxin were associated with toxin-induced ADP-ribosylation of a 41 kDa protein. Furthermore, the stimulatory effects of TGF beta 1 on c-sis mRNA expression were shown to be pertussis-toxin sensitive and could be mimicked by direct activation of G-proteins with AIF4-. These results demonstrate that in AKR-2B cells a pertussis-toxin-sensitive guanine nucleotide regulatory protein(s) is coupled to TGF beta 1 receptor binding.

scholarly journals Regulation of fibroblast procollagen production. Transforming growth factor-β1 induces prostaglandin E2 but not procollagen synthesis via a pertussis toxin-sensitive G-protein

1995 ◽  
Vol 307 (1) ◽  
pp. 63-68 ◽  
Author(s):  
R J McAnulty ◽  
R C Chambers ◽  
G J Laurent
Keyword(s):  
Growth Factor ◽  
Prostaglandin E2 ◽  
G Protein ◽  
Pertussis Toxin ◽  
Transforming Growth Factor ◽  
Pge2 Production ◽  
Lung Fibroblasts ◽  
Extracellular Matrix Protein ◽  
Dependent Manner ◽  
Tgf Beta

Transforming growth factor-beta 1 (TGF beta 1) initiates a series of signalling events resulting in diverse cellular responses including stimulation of extracellular matrix protein production. In this study we have investigated the role of pertussis toxin-sensitive G-proteins in mediating the effects of TGF beta 1 on fibroblast procollagen metabolism. TGF beta 1 stimulated human fetal lung fibroblast procollagen synthesis and production in a dose-dependent manner which was maximal at 0.5 ng/ml. TGF beta 1 also decreased the proportion of newly synthesized procollagen degraded intracellularly. Pertussis toxin, a G-protein inhibitor, further stimulated TGF beta 1-induced procollagen synthesis and production, but alone it had no effect on fibroblast procollagen metabolism. Addition of indomethacin also potentiated the TGF beta 1-induced increase in procollagen synthesis and production. The effects of pertussis toxin and indomethacin were not additive. Pertussis toxin and indomethacin did not affect the proportion of newly synthesized procollagen degraded intracellularly, either alone or in combination, by control cells. The TGF beta 1-induced decrease in intracellular procollagen degradation was maintained but not further affected by pertussis toxin or indomethacin. TGF beta 1 increased prostaglandin E2 (PGE2) compared with PGE2 production by control cells. Addition of pertussis toxin or indomethacin blocked the TGF beta 1-induced increase in PGE2 production. The TGF beta 1-induced increase in PGE2 preceded the increase in procollagen production. These results demonstrate that TGF beta 1-induced procollagen synthesis by lung fibroblasts is modulated by production of PGE2. Pertussis toxin and indomethacin block the production of PGE2 and enhance the effect of TGF beta 1 on procollagen synthesis. From these data we conclude that the effects of TGF beta 1 on PGE2 production but not procollagen synthesis are mediated via a receptor linked to a pertussis toxin-sensitive G-protein.

Expression and secretion of transforming growth factor-beta by bleomycin-stimulated rat alveolar macrophages

1993 ◽  
Vol 264 (1) ◽  
pp. L36-L42 ◽  
Author(s):  
E. M. Denholm ◽  
S. M. Rollins
Keyword(s):  
Growth Factor ◽  
Alveolar Macrophages ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Chemotactic Activity ◽  
Beta Activity ◽  
Dependent Manner ◽  
Tgf Beta ◽  
Growth Factor Beta

Bleomycin-induced fibrosis in rodents has been used extensively as a model of human pulmonary fibrosis. The influx of monocytes observed during the early stages of fibrosis is at least partially regulated by the elaboration of chemotactic factors in the lung. Exposure of alveolar macrophages (AM phi) to bleomycin either in vivo or in vitro stimulated secretion of monocyte chemotactic activity (MCA). This MCA has been previously characterized as being primarily due to fibronectin fragments. The present experiments revealed that bleomycin also induced AM phi to secrete a second chemotactic factor, transforming growth factor-beta (TGF-beta). However, the TGF-beta secreted by macrophages was in latent form, since no TGF-beta activity was detected unless AM phi conditioned medium (CM) was acid-activated. After acidification, chemotactic activity in CM from AM phi stimulated with bleomycin in vitro was increased by 3.6, whereas activity in AM phi CM from fibrotic rats increased by 2 and that of a bleomycin-stimulated AM phi cell line increased by 1.6. This acid-activatable chemotactic activity was inhibited by antibody to TGF-beta. Bleomycin-stimulated AM phi s secreted significantly more TGF-beta than did unstimulated controls. Further, in vitro exposure of AM phi to bleomycin induced TGF-beta mRNA expression in a time- and concentration-dependent manner, with maximal mRNA being detected following a 16-h incubation with 1 microgram/ml bleomycin.

Abscisic acid induction of GTP hydrolysis in maize coleoptile plasma membranes

1998 ◽  
Vol 25 (5) ◽  
pp. 539 ◽  
Author(s):  
Helen R. Irving
Keyword(s):  
Abscisic Acid ◽  
G Protein ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Plasma Membranes ◽  
Dependent Manner ◽  
Gtpase Activity ◽  
Heterotrimeric G Proteins ◽  
Gtp Hydrolysis ◽  
Maize Coleoptile

Since receptor-coupled G proteins increase GTP hydrolysis (GTPase) activity upon ligands binding to the receptor, a study was undertaken to determine if abscisic acid (ABA) induced such an effect. Plasma membranes isolated from etiolated maize (Zea mays L.) coleoptiles were enriched in GTPase activity relative to microsomal fractions. Vanadate was included in the assay to inhibit the high levels of vanadate sensitive low affinity GTPases present. Under these conditions, GTPase activity was enhanced by Mg2+, stimulated by mastoparan, and inhibited by GTPγS indicating the presence of either monomeric or heterotrimeric G proteins. The combination of NaF and AlCl3 is expected to inhibit heterotrimeric G protein activity but had little effect on GTPase activity in maize coleoptile membranes. Cholera toxin enhanced basal GTPase activity, confirming the presence of heterotrimeric G proteins in maize plasma membranes. Pertussis toxin also slightly enhanced basal GTPase activity in maize membranes. Abscisic acid enhanced GTPase activity optimally at 5 mmol/L Mg2+ in a concentration dependent manner by 1.5-fold at 10 µmol/L and up to three-fold at 100 µmol/L ABA. Abscisic acid induced GTPase activity was inhibited by GTPγS, the combination of NaF and AlCl3, and pertussis toxin. Overall, these results are typical of a receptor-coupled G protein responding to its ligand.

scholarly journals Transforming growth factor beta abrogates the effects of hematopoietins on eosinophils and induces their apoptosis.

1994 ◽  
Vol 179 (3) ◽  
pp. 1041-1045 ◽  
Author(s):  
R Alam ◽  
P Forsythe ◽  
S Stafford ◽  
Y Fukuda
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Dependent Manner ◽  
Tgf Beta ◽  
Gm Csf ◽  
Eosinophil Survival ◽  
Growth Factor Beta ◽  
Induced Apoptosis ◽  
And Function

Hematopoietins, interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF) have previously been shown to prolong eosinophil survival and abrogate apoptosis. The objective of this study was to investigate the effect of transforming growth factor beta (TGF-beta) on eosinophil survival and apoptosis. Eosinophils from peripheral blood of mildly eosinophilic donors were isolated to > 97% purity using discontinuous Percoll density gradient. Eosinophils were cultured with hematopoietins with or without TGF-beta for 4 d and their viability was assessed. We confirmed previous observations that hematopoietins prolonged eosinophil survival and inhibited apoptosis. TGF-beta at concentrations > or = 10(-12) M abrogated the survival-prolonging effects of hematopoietins in a dose-dependent manner and induced apoptosis as determined by DNA fragmentation in agarose gels. The effect of TGF-beta was blocked by an anti-TGF-beta antibody. The anti-TGF-beta antibody also prolonged eosinophil survival on its own. The culture of eosinophils with IL-3 and GM-CSF stimulated the synthesis of GM-CSF and IL-5, respectively, suggesting an autocrine mechanism of growth factor production. TGF-beta inhibited the synthesis of GM-CSF and IL-5 by eosinophils. TGF-beta did not have any effect on the expression of GM-CSF receptors on eosinophils. We also studied the effect of TGF-beta on eosinophil function and found that TGF-beta inhibited the release of eosinophil peroxidase. Thus, TGF-beta seems to inhibit eosinophil survival and function. The inhibition of endogenous synthesis of hematopoietins may be one mechanism by which TGF-beta blocks eosinophil survival and induces apoptosis.

scholarly journals Retinoic acid and transforming growth factor β differentially inhibit platelet-derived-growth-factor-induced Ito-cell activation

1991 ◽  
Vol 278 (1) ◽  
pp. 43-47 ◽  
Author(s):  
B H Davis ◽  
U R Rapp ◽  
N O Davidson
Keyword(s):  
Retinoic Acid ◽  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Cell Activation ◽  
Cellular Proliferation ◽  
Transforming Growth Factor ◽  
Platelet Derived Growth Factor ◽  
Tgf Beta ◽  
Ito Cell ◽  
Ito Cells

Sinusoidal Ito cells (stellate or fat-storing cells) undergo excessive cellular proliferation before the establishment and progression of hepatic fibrosis and cirrhosis. Retinoic acid and transforming growth factor beta (TGF beta) both inhibit Ito-cell [3H]thymidine incorporation in serum-containing media. Serum-induced mitogenicity was dependent on platelet-derived growth factor (PDGF). Additionally, pre-treatment of Ito cells with retinoic acid and TGF beta blocked PDGF-induced cell proliferation. TGF beta, but not retinoic acid, diminished PDGF-receptor and smooth-muscle alpha-actin abundance.

scholarly journals Role of the latent TGF-beta binding protein in the activation of latent TGF-beta by co-cultures of endothelial and smooth muscle cells.

1993 ◽  
Vol 120 (4) ◽  
pp. 995-1002 ◽  
Author(s):  
R Flaumenhaft ◽  
M Abe ◽  
Y Sato ◽  
K Miyazono ◽  
J Harpel ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Muscle Cells ◽  
Beta Activity ◽  
Dependent Manner ◽  
Tgf Beta

Transforming growth factor beta (TGF-beta) is released from cells in a latent form consisting of the mature growth factor associated with an aminoterminal propeptide and latent TGF-beta binding protein (LTBP). The endogenous activation of latent TGF-beta has been described in co-cultures of endothelial and smooth muscle cells. However, the mechanism of this activation remains unknown. Antibodies to native platelet LTBP and to a peptide fragment of LTBP inhibit in a dose-dependent manner the activation of latent TGF-beta normally observed when endothelial cells are cocultured with smooth muscle cells. Inhibition of latent TGF-beta activation was also observed when cells were co-cultured in the presence of an excess of free LTBP. These data represent the first demonstration of a function for the LTBP in the extracellular regulation of TGF-beta activity and indicate that LTBP participates in the activation of latent TGF-beta, perhaps by concentrating the latent growth factor on the cell surface where activation occurs.

scholarly journals A growth factor for cardiac myocytes is produced by cardiac nonmyocytes.

1991 ◽  
Vol 2 (12) ◽  
pp. 1081-1095 ◽  
Author(s):  
C S Long ◽  
C J Henrich ◽  
P C Simpson
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Cardiac Myocytes ◽  
Transforming Growth Factor Beta ◽  
Cardiac Myocyte ◽  
Transforming Growth Factor ◽  
Tnf Alpha ◽  
Dependent Manner ◽  
Tgf Beta ◽  
Hypertrophic Growth

Cardiac nonmyocytes, primarily fibroblasts, surround cardiac myocytes in vivo. We examined whether nonmyocytes could modulate myocyte growth by production of one or more growth factors. Cardiac myocyte hypertrophic growth was stimulated in cultures with increasing numbers of cardiac nonmyocytes. This effect of nonmyocytes on myocyte size was reproduced by serum-free medium conditioned by the cardiac nonmyocytes. The majority of the nonmyocyte-derived myocyte growth-promoting activity bound to heparin-Sepharose and was eluted with 0.75 M NaCl. Several known polypeptide growth factors found recently in cardiac tissue, namely acidic fibroblast growth factor (aFGF), basic FGF (bFGF), platelet-derived growth factor (PDGF), tumor necrosis factor alpha (TNF alpha), and transforming growth factor beta 1 (TGF beta 1), also caused hypertrophy of cardiac myocytes in a dose-dependent manner. However, the nonmyocyte-derived growth factor (tentatively named NMDGF) could be distinguished from these other growth factors by different heparin-Sepharose binding profiles (TNF alpha, aFGF, bFGF, and TGF beta 1) by neutralizing growth factor-specific antisera (PDGF, TNF alpha, aFGF, bFGF, and TGF beta 1), by the failure of NMDGF to stimulate phosphatidylinositol hydrolysis (PDGF and TGF beta 1), and, finally, by the apparent molecular weight of NMDGF (45-50 kDa). This nonmyocyte-derived heparin-binding growth factor may represent a novel paracrine growth mechanism in myocardium.

scholarly journals Beta-type transforming growth factor specifies organizational behavior in vascular smooth muscle cell cultures.

1987 ◽  
Vol 105 (1) ◽  
pp. 465-471 ◽  
Author(s):  
R A Majack
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Organizational Behavior ◽  
Transforming Growth Factor ◽  
Cell Types ◽  
Cell Contact ◽  
Dependent Manner ◽  
Tgf Beta ◽  
The Hill

In culture, vascular smooth muscle cells (SMC) grow in a "hill-and-valley" (multilayered) pattern of organization. We have studied the growth, behavioral organization, and biosynthetic phenotype of rat aortic SMC exposed to purified platelet-derived growth regulatory molecules. We show that multilayered growth is not a constitutive feature of cultured SMC, and that beta-type transforming growth factor (TGF-beta) is the primary determinant of multilayered growth and the hill-and-valley pattern of organization diagnostic for SMC in culture. TGF-beta inhibited, in a dose-dependent manner, the serum- or platelet-derived growth factor-mediated proliferation of these cells in two-dimensional culture, but only when cells were plated at subconfluent densities. The ability of TGF-beta to inhibit SMC growth was inversely correlated to plating cell density. When SMC were plated at monolayer density (5 X 10(4) cells/cm2) to allow maximal cell-to-cell contact, TGF-beta potentiated cell growth. This differential response of SMC to TGF-beta may contribute to the hill-and-valley pattern of organization. Unlike its effect on other cell types, TGF-beta did not enhance the synthesis of fibronectin or its incorporation into the extracellular matrix. However, the synthesis of a number of other secreted proteins was altered by TGF-beta treatment. SMC treated with TGF-beta for 4 or 8 h secreted markedly enhanced amounts of an Mr 38,000-D protein doublet whose synthesis is known to be increased by heparin (another inhibitor of SMC growth), suggesting metabolic similarities between heparin- and TGF-beta-mediated SMC growth inhibition. The data suggest that TGF-beta may play an important and complex regulatory role in SMC proliferation and organization during development and after vascular injury.

scholarly journals Quercetin inhibits the growth of leukemic progenitors and induces the expression of transforming growth factor-beta 1 in these cells

Blood ◽  
1995 ◽  
Vol 85 (12) ◽  
pp. 3654-3661 ◽  
Author(s):  
LM Larocca ◽  
L Teofili ◽  
S Sica ◽  
M Piantelli ◽  
N Maggiano ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Inhibitory Activity ◽  
Transforming Growth Factor ◽  
Dependent Manner ◽  
Tgf Beta ◽  
Acute Leukemias ◽  
Growth Inhibitory ◽  
Growth Inhibitory Activity ◽  
Growth Factor Beta

We previously showed that quercetin (3,3′,4′,5,7 pentahydroxyflavone) inhibits in a dose-dependent manner the growth of acute leukemias and is able to enhance the antiproliferative activity of cytosine arabinoside. We show here that quercetin inhibits the clonogenic activity of 20 of 22 acute leukemias (AL; 4 M1-AML, 3 M2-AML, 2 M3-AML, 3 M4-AML, 3 M5-AML, and 7 ALL). In the present report, we show that the induction of transforming growth factor-beta 1 (TGF-beta 1) in leukemic blasts is one of the growth-inhibitory mechanisms of quercetin in these cells. This observation was supported by the following data. (1) Quercetin-sensitive leukemic blasts, when treated with quercetin, secrete large amounts of TGF-beta 1 in the medium and show positivity for TGF-beta 1-immunoreactive material in the cytoplasm. (2) At a concentration of 8 mumol/L, antisense TGF-beta 1 oligonucleotides prevent the growth-inhibitory action of quercetin. (3) Anti-TGF-beta 1 neutralizing monoclonal antibodies can prevent almost completely the growth-inhibitory activity of quercetin. The analysis of quercetin-resistant cases confirmed as well the central role of TGF-beta 1 in the growth-inhibitory activity of quercetin. In conclusion, quercetin can act as a cytostatic agent for leukemic cells by modulating the production of TGF-beta 1.

scholarly journals Inhibition of mink lung epithelial cell proliferation by transforming growth factor-β is coupled through a pertussis-toxin-sensitive substrate

1990 ◽  
Vol 266 (2) ◽  
pp. 537-543 ◽  
Author(s):  
P H Howe ◽  
M R Cunningham ◽  
E B Leof
Keyword(s):  
Growth Factor ◽  
Epithelial Cells ◽  
Growth Inhibition ◽  
G Protein ◽  
Pertussis Toxin ◽  
Transforming Growth Factor ◽  
Chemical Mutagenesis ◽  
Type I ◽  
Tgf Beta ◽  
Lung Epithelial

Transforming growth factor beta 1 (TGF beta 1) inhibits the proliferative response of mink lung epithelial cells (CCL64) to serum and to epidermal growth factor (EGF). This response to TGF beta 1 can be inhibited by prior exposure of the cells to nanogram concentrations of pertussis toxin (PT), suggesting the involvement of a guanine-nucleotide-binding regulatory protein (G-protein) in mediating TGF beta 1-induced growth inhibition. To characterize further this G-protein dependence, we have isolated, by chemical mutagenesis, a CCL64 variant (CCL64-D1) that is resistant to TGF beta 1. Whereas in the parental CCL64 cells TGF beta 1 stimulates both GTP[35S] (guanosine 5′-[gamma-[35S]thio]triphosphate) binding and GTPase activity, in the CCL64-D1 variants TGF beta 1 is without effect. Quantitative immunoblotting with antisera for G-protein alpha- and beta-subunits, as well as PT-catalysed ADP-ribosylation analyses, revealed no appreciable changes in the level of G-protein expression in the CCL64-D1 variants compared with parental cells. In contrast with another TGF beta-resistant clone, MLE-M, which we show lacks detectable type I receptor protein, the CCL64-D1 cells retain all three TGF beta cell-surface binding proteins. On the basis of these studies, we propose that a necessary component of TGF beta 1-mediated growth inhibition in CCL64 epithelial cells is the coupling of TGF beta 1 receptor binding to G-protein activation.

Sign in / Sign up

Export Citation Format

Share Document