scholarly journals Alterations of G-protein coupling function in phosphoinositide signaling pathways of cells transformed by ras and other membrane-associated and cytoplasmic oncogenes.

1990 ◽  
Vol 10 (6) ◽  
pp. 3117-3124 ◽  
Author(s):  
T Alonso ◽  
S Srivastava ◽  
E Santos
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Protein S ◽  
3T3 Cells ◽  
Phosphoinositide Signaling ◽  
Common Effect ◽  
Receptor Number ◽  
Ras Oncogenes ◽  
Nih 3T3 ◽  
Functional Alteration

We showed previously that transformation by cytoplasmic and membrane-associated oncogenes including ras results in uncoupling between surface stimulation by platelet-derived growth factor, bombesin, and serum and activation of intracellular phospholipase C (PLC); this uncoupling does not involve alterations at the receptor or effector enzyme levels (T. Alonso, R. O. Morgan, J. C. Marvizon, H. Zarbl, and E. Santos, Proc. Natl. Acad. Sci. USA 85:4271-4275, 1988). In this study, we stimulated normal and oncogene-transformed NIH 3T3 cells with fluoroaluminate (AIF4-), thus directly activating PLC-associated G protein(s) and bypassing the receptor step. A1F4(-)-elicited PLC responses were significantly impaired in transformed cells when compared with those in their normal counterparts, suggesting that the uncoupling of PLC is the result, at least in part, of functional impairment at the G-protein level. Transformation by ras oncogenes has also been reported to result in enhanced PLC response to bradykinin resulting from increased receptor numbers (G. Parries, R. Hoebel, and E. Racker, Proc. Natl. Acad. Sci. USA 84:2648-2652, 1987; J. Downward, J. de Gunzburg, R. Riehl, and R. Weinberg, Proc. Natl. Acad. Sci. USA 85:5774-5778, 1988). We demonstrate here that transformation by other membrane-associated and cytoplasmic oncogenes also results in increased responsiveness to bradykinin ("supercoupling") and enhanced receptor numbers. However, there is no direct correlation between the number of receptors and the enhancement in responsiveness, suggesting that other factors besides receptor number are also involved in the enhanced responses. We propose that a common effect of transformation by cytoplasmic and membrane-associated oncogenes is functional alteration of coupling G proteins and that a similar modification of different kinds of G proteins may account for the pleiotropic alterations of signal transduction (uncoupling and supercoupling) observed.

Alterations of G-protein coupling function in phosphoinositide signaling pathways of cells transformed by ras and other membrane-associated and cytoplasmic oncogenes

1990 ◽  
Vol 10 (6) ◽  
pp. 3117-3124
Author(s):  
T Alonso ◽  
S Srivastava ◽  
E Santos
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Protein S ◽  
3T3 Cells ◽  
Phosphoinositide Signaling ◽  
Common Effect ◽  
Receptor Number ◽  
Ras Oncogenes ◽  
Nih 3T3 ◽  
Functional Alteration

We showed previously that transformation by cytoplasmic and membrane-associated oncogenes including ras results in uncoupling between surface stimulation by platelet-derived growth factor, bombesin, and serum and activation of intracellular phospholipase C (PLC); this uncoupling does not involve alterations at the receptor or effector enzyme levels (T. Alonso, R. O. Morgan, J. C. Marvizon, H. Zarbl, and E. Santos, Proc. Natl. Acad. Sci. USA 85:4271-4275, 1988). In this study, we stimulated normal and oncogene-transformed NIH 3T3 cells with fluoroaluminate (AIF4-), thus directly activating PLC-associated G protein(s) and bypassing the receptor step. A1F4(-)-elicited PLC responses were significantly impaired in transformed cells when compared with those in their normal counterparts, suggesting that the uncoupling of PLC is the result, at least in part, of functional impairment at the G-protein level. Transformation by ras oncogenes has also been reported to result in enhanced PLC response to bradykinin resulting from increased receptor numbers (G. Parries, R. Hoebel, and E. Racker, Proc. Natl. Acad. Sci. USA 84:2648-2652, 1987; J. Downward, J. de Gunzburg, R. Riehl, and R. Weinberg, Proc. Natl. Acad. Sci. USA 85:5774-5778, 1988). We demonstrate here that transformation by other membrane-associated and cytoplasmic oncogenes also results in increased responsiveness to bradykinin ("supercoupling") and enhanced receptor numbers. However, there is no direct correlation between the number of receptors and the enhancement in responsiveness, suggesting that other factors besides receptor number are also involved in the enhanced responses. We propose that a common effect of transformation by cytoplasmic and membrane-associated oncogenes is functional alteration of coupling G proteins and that a similar modification of different kinds of G proteins may account for the pleiotropic alterations of signal transduction (uncoupling and supercoupling) observed.

scholarly journals Bombesin and thrombin affect discrete pools of intracellular calcium through different G-proteins

1996 ◽  
Vol 320 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Jin-Lin WANG ◽  
Somasundaram KALYANARAMAN ◽  
Michael DE VIVO ◽  
Narasimhan GAUTAM
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Signalling Pathways ◽  
3T3 Cells ◽  
Atpase Inhibitor ◽  
Protein Subunit ◽  
Stable Transfectants ◽  
Bombesin Receptor ◽  
Nih 3T3

In mouse NIH 3T3 cells, the mitogens bombesin and thrombin induced Ca2+ release from intracellular stores. Ca2+ release induced by bombesin was inhibited by the Ca2+-ATPase inhibitor thapsigargin, while Ca2+ release induced by thrombin was unaffected by this agent. The Ca2+-release response to bombesin was not affected by pertussis toxin, but the response to thrombin was abolished by the toxin. Stable transfectants overexpressing the G-protein subunit type αq showed an accentuated response to bombesin, indicating that the bombesin receptor was coupled to a Gq-like G-protein. Together, these results show that the two mitogenic receptors are coupled to distinct G-proteins that affect functionally different pools of Ca2+. Organization of signalling pathways in this manner may allow cells to differentially encode information from different signals.

Mutated alpha subunit of the Gq protein induces malignant transformation in NIH 3T3 cells

1992 ◽  
Vol 12 (10) ◽  
pp. 4687-4693
Author(s):  
G Kalinec ◽  
A J Nazarali ◽  
S Hermouet ◽  
N Xu ◽  
J S Gutkind
Keyword(s):  
Adenylyl Cyclase ◽  
G Proteins ◽  
Alpha Subunit ◽  
Endocrine Tumors ◽  
3T3 Cells ◽  
Activating Mutations ◽  
Alpha Subunits ◽  
G Alpha Q ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

The discovery of mutated, GTPase-deficient alpha subunits of Gs or Gi2 in certain human endocrine tumors has suggested that heterotrimeric G proteins play a role in the oncogenic process. Expression of these altered forms of G alpha s or G alpha i2 proteins in rodent fibroblasts activates or inhibits endogenous adenylyl cyclase, respectively, and causes certain alterations in cell growth. However, it is not clear whether growth abnormalities result from altered cyclic AMP synthesis. In the present study, we asked whether a recently discovered family of G proteins, Gq, which does not affect adenylyl cyclase activity, but instead mediates the activation of phosphatidylinositol-specific phospholipase C harbors transforming potential. We mutated the cDNA for the alpha subunit of murine Gq in codons corresponding to a region involved in binding and hydrolysis of GTP. Similar mutations unmask the transforming potential of p21ras or activate the alpha subunits of Gs or Gi2. Our results show that when expressed in NIH 3T3 cells, activating mutations convert G alpha q into a dominant acting oncogene.

Activation of c-myc and c-K-ras oncogenes in primary rat tumors induced by ionizing radiation

1987 ◽  
Vol 7 (2) ◽  
pp. 932-935
Author(s):  
M J Sawey ◽  
A T Hood ◽  
F J Burns ◽  
S J Garte
Keyword(s):  
Ionizing Radiation ◽  
Tissue Specificity ◽  
3T3 Cells ◽  
Rat Skin ◽  
Oncogene Activation ◽  
Myc Gene ◽  
Ras Oncogenes ◽  
Restriction Polymorphisms ◽  
Rat Tumors ◽  
Nih 3T3

An activated K-ras oncogene was detected by transfection in NIH 3T3 cells and by Southern blot analysis in 6 of 12 rat skin tumors induced by ionizing radiation. The DNA from 10 of the 12 tumors also showed c-myc gene amplification and restriction polymorphisms. Evidence for tissue specificity was observed in patterns of oncogene activation, with each of three clear cell carcinomas exhibiting activation of both c-myc and K-ras oncogenes.

Diacylglycerol and ceramide formation induced by dopamine D2S receptors via Gβγ-subunits in Balb/c-3T3 cells

2003 ◽  
Vol 284 (3) ◽  
pp. C640-C648 ◽  
Author(s):  
Gele Liu ◽  
Mohammad H. Ghahremani ◽  
Behzad Banihashemi ◽  
Paul R. Albert
Keyword(s):  
Cell Growth ◽  
Phospholipase C ◽  
G Protein ◽  
G Proteins ◽  
Second Messengers ◽  
Mitogen Activated Protein Kinase ◽  
Fibroblast Cells ◽  
Induced Responses ◽  
3T3 Cells ◽  
Mitogen Activated Protein

Diacylglycerol (DAG) and ceramide are important second messengers affecting cell growth, differentiation, and apoptosis. Balb/c-3T3 fibroblast cells expressing dopamine-D2S (short) receptors (Balb-D2S cells) provide a model of G protein-mediated cell growth and transformation. In Balb-D2S cells, apomorphine (EC50= 10 nM) stimulated DAG and ceramide formation by 5.6- and 4.3-fold, respectively, maximal at 1 h and persisting over 6 h. These actions were blocked by pretreatment with pertussis toxin (PTX), implicating Gi/Goproteins. To address which G proteins are involved, Balb-D2S clones expressing individual PTX-insensitive Gαiproteins were treated with PTX and tested for apomorphine-induced responses. Neither PTX-insensitive Gαi2nor Gαi3rescued D2S-induced DAG or ceramide formation. Both D2S-induced DAG and ceramide signals required Gβγ-subunits and were blocked by inhibitors of phospholipase C [1-(6-[([17β]-3-methoxyestra-1,2,3[10]-trien- 17yl)amino]hexyl)-1H-pyrrole-2,5-dione (U-73122) and partially by D609]. The similar G protein specificity of D2S-induced calcium mobilization, DAG, and ceramide formation indicates a common Gβγ-dependent phospholipase C-mediated pathway. Both D2 agonists and ceramide specifically induced mitogen-activated protein kinase (ERK1/2), suggesting that ceramide mediates a novel pathway of D2S-induced ERK1/2 activation, leading to cell growth.

scholarly journals NIH/3T3 cells transfected with human tumor DNA containing activated ras oncogenes express the metastatic phenotype in nude mice.

1985 ◽  
Vol 5 (1) ◽  
pp. 259-262 ◽  
Author(s):  
U P Thorgeirsson ◽  
T Turpeenniemi-Hujanen ◽  
J E Williams ◽  
E H Westin ◽  
C A Heilman ◽  
...  
Keyword(s):  
Nude Mice ◽  
Dna Sequences ◽  
Immune Cell ◽  
Human Tumor ◽  
3T3 Cells ◽  
Metastatic Phenotype ◽  
Ras Oncogenes ◽  
Nih 3T3 ◽  
Tumor Dna ◽  
Nih 3T3 Cells

NIH/3T3 cells transfected with DNA from malignant human tumors produced experimental and spontaneous metastases in nude mice. In contrast, parent or spontaneously transformed NIH/3T3 cells failed to metastasize. The transfected clones contained either activated c-Harvey-ras or N-ras oncogenes. A representative clone (T71-17SA2) which was used to assess selected cellular and host factors relevant to the metastatic process produced lung metastases in 100% of the NIH nude mice recipients, secreted augmented levels of type IV collagenase, and invaded human amnion basement membrane in vitro. Expression of the metastatic phenotype was not related to decreased sensitivity to natural killer cells or macrophage-mediated cytotoxicity. Analysis of the cellular DNA from the T71-17SA2 transfectant and its corresponding metastases, both of which contained activated N-ras oncogenes, revealed a twofold increase in the N-ras-specific DNA sequences in the metastatic cells. Thus, transfection with human tumor DNA containing activated ras oncogenes can induce the complete metastatic phenotype in NIH/3T3 cells by a mechanism apparently unrelated to immune cell killing.

scholarly journals Differential effects of G-protein activators on 5-hydroxytryptamine and platelet-derived growth factor release from streptolysin-O-permeabilized human platelets

1996 ◽  
Vol 314 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Philip J. PADFIELD ◽  
Ninder PANESAR ◽  
Patricia HENDERSON ◽  
Joseph J. BALDASSARE
Keyword(s):  
Growth Factor ◽  
G Protein ◽  
G Proteins ◽  
Protein S ◽  
Human Platelets ◽  
Dense Core ◽  
Platelet Derived Growth Factor ◽  
Permeabilized Cells ◽  
Streptolysin O ◽  
Dense Core Granules

In this paper we have used streptolysin O (SLO)-permeabilized human platelets to examine the G-protein(s) that control Ca2+-independent secretion from α and dense-core granules. As shown for electropermeabilized platelets, Ca2+ alone stimulated a concentration-dependent increase in 5-hydroxytryptamine (5-HT) (dense-core-granule marker) and platelet-derived growth factor (PDGF) (α-granule marker) release from the SLO-permeabilized cells. The EC50 values for Ca2+-dependent 5-HT and PDGF release were 5 μM and 10 μM respectively. Guanosine 5´-[γ-thio]triphosphate (GTP[S]) (100 μM) stimulated Ca2+-independent release from both α and dense-core granules. In contrast, AlF4- had no effect on Ca2+-independent release from either α or dense-core granules. Neither GTP[S] nor AlF4- appeared to have a significant effect on Ca2+-dependent release from α and dense-core granules. GTP[S] can activate both heterotrimeric and low-molecular-mass G-proteins, whereas AlF4- activates only heterotrimeric G-proteins. Our results, therefore suggest that secretion in the human platelet is regulated by a small G-protein. Both GTP[S]- and Ca2+-dependent secretion were effected by extending the time between permeabilization with SLO and stimulation of secretion. GTP[S]-stimulated secretion from α and dense-core granules decreased rapidly after permeabilization. In contrast, Ca2+-dependent 5-HT and PDGF release ran down at a much lower rate. These observations indicate that GTP[S] and Ca2+ act through parallel pathways to stimulate secretion from SLO-permeabilized platelets.

NIH/3T3 cells transfected with human tumor DNA containing activated ras oncogenes express the metastatic phenotype in nude mice

1985 ◽  
Vol 5 (1) ◽  
pp. 259-262
Author(s):  
U P Thorgeirsson ◽  
T Turpeenniemi-Hujanen ◽  
J E Williams ◽  
E H Westin ◽  
C A Heilman ◽  
...  
Keyword(s):  
Nude Mice ◽  
Dna Sequences ◽  
Immune Cell ◽  
Human Tumor ◽  
3T3 Cells ◽  
Metastatic Phenotype ◽  
Ras Oncogenes ◽  
Nih 3T3 ◽  
Tumor Dna ◽  
Nih 3T3 Cells

NIH/3T3 cells transfected with DNA from malignant human tumors produced experimental and spontaneous metastases in nude mice. In contrast, parent or spontaneously transformed NIH/3T3 cells failed to metastasize. The transfected clones contained either activated c-Harvey-ras or N-ras oncogenes. A representative clone (T71-17SA2) which was used to assess selected cellular and host factors relevant to the metastatic process produced lung metastases in 100% of the NIH nude mice recipients, secreted augmented levels of type IV collagenase, and invaded human amnion basement membrane in vitro. Expression of the metastatic phenotype was not related to decreased sensitivity to natural killer cells or macrophage-mediated cytotoxicity. Analysis of the cellular DNA from the T71-17SA2 transfectant and its corresponding metastases, both of which contained activated N-ras oncogenes, revealed a twofold increase in the N-ras-specific DNA sequences in the metastatic cells. Thus, transfection with human tumor DNA containing activated ras oncogenes can induce the complete metastatic phenotype in NIH/3T3 cells by a mechanism apparently unrelated to immune cell killing.

ROLE OF RECEPTORS COUPLED TO G PROTEINS IN CELL DIVISION: THE EXAMPLE OF 5-HT1A RECEPTORS TRANSFECTED IN NIH-3T3 CELLS

1992 ◽  
Vol 76 (2) ◽  
pp. 212-212
Author(s):  
Bockaert Joël ◽  
Varrault Annie ◽  
Waeber Christian
Keyword(s):  
Cell Division ◽  
G Proteins ◽  
3T3 Cells ◽  
Nih 3T3 ◽  
Nih 3T3 Cells
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