The phosphatidylinositol signalling system in elongating bovine blastocysts; formation of phosphoinositides, inositol phosphates and stimulation by growth factors

2002 ◽  
Vol 14 (8) ◽  
pp. 515 ◽  
Author(s):  
A. C. Hynes ◽  
J. M. Sreenan ◽  
M. T. Kane
Keyword(s):  
Signal Transduction ◽  
Growth Factors ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Signal Transduction System ◽  
Signalling System ◽  
Sodium Dependent ◽  
Epidermal Growth

The uptake of myo-inositol and its incorporation into the phosphoinositides and inositol phosphates of the phosphatidylinositol (PtdIns) signal transduction system by in vivo elongating cattle blastocysts was investigated using [3H]myo-inositol. Uptake was examined in 13-, 14- and 16-day-old blastocysts and was largely sodium-dependent throughout (P<0.001), indicating the presence of a sodium-dependent inositol transporter. Incorporation of inositol into the three phosphoinositides, PtdIns, PtdInsP and PtdInsP2, and the inositol phosphates of the phosphatidylinositol signal transduction system was examined at Days 14 and 16; incorporation into the three phosphoinositides and into the inositol phosphate species, InsP1, InsP2, InsP3 (including the second messenger, Ins(1,4,5)P3) and InsP4 was detected in both blastocyst stages. The effects of the peptide growth factor, epidermal growth factor (EGF), and the lipid growth factors, lysophosphatidic acid (LPA) and platelet activating factor (PAF), on the activity of the phosphatidylinositol signalling system in 14- and 16-day-old blastocysts were examined. All growth factors significantly stimulated phosphatidylinositol signalling activity. Epidermal growth factor was stimulatory (P<0.001) only in 16-day-old blastocysts, whereas LPA and PAF were active in both 14- (P<0.005 for LPA and P<0.001 for PAF) and 16-day-old blastocysts (P<0.001 for LPA and PAF). These results indicate that the phosphatidylinositol signalling system is present in cattle blastocysts at the elongation stage and is responsive to stimulation by growth factors.

scholarly journals BALB/c-3T3 fibroblasts resistant to growth inhibition by beta interferon exhibit aberrant platelet-derived growth factor, epidermal growth factor, and fibroblast growth factor signal transduction.

1991 ◽  
Vol 11 (6) ◽  
pp. 3148-3154 ◽  
Author(s):  
L J Mundschau ◽  
D V Faller
Keyword(s):  
Signal Transduction ◽  
Growth Factors ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Signal Transduction Pathway ◽  
Platelet Derived Growth Factor ◽  
Fibroblast Growth ◽  
Transduction Pathway ◽  
Double Stranded Rna ◽  
Epidermal Growth

Several lines of evidence now exist to suggest an interaction between the platelet-derived growth factor (PDGF) growth-stimulatory signal transduction pathway and the beta interferon (IFN-beta) growth-inhibitory signal transduction pathway. The most direct examples are inhibition of PDGF-mediated gene induction and mitogenesis by IFN-beta and the effects of activators and inhibitors of the IFN-inducible double-stranded RNA-dependent eIF2 kinase on expression of PDGF-inducible genes. To further investigate the nature of this PDGF/IFN-beta interaction, we selected BALB/c-3T3 cells for resistance to growth inhibition by IFN-beta and analyzed the phenotypes of resulting clonal lines (called IRB cells) with respect to PDGF signal transduction. Although selected only for IFN resistance, the IRB cells were found to be defective for induction of growth-related genes c-fos, c-myc and JE in response to PDGF. This block to signal transduction was not due to loss or inactivation of PDGF receptors, as immunoprecipitation of PDGF receptors with antiphosphotyrosine antibodies showed them to be present at equal levels in the BALB/c-3T3 and IRB cells and to be autophosphorylated normally in response to PDGF. Furthermore, treatment with other peptide growth factors (PDGF-AA, fibroblast growth factor, and epidermal growth factor) also failed to induce c-fos, c-myc, or JE expression in IRB cells. All of these growth factors, however, were able to induce another early growth-related gene, Egr-1. The block to signaling was not due to a defect in inositol phosphate metabolism, as PDGF treatment induced normal calcium mobilization and phosphotidylinositol-3-kinase activation in these cells. Activation of protein kinase C by phorbol esters did induce c-fos, c-myc, and JE in IRB cells, indicating that signalling pathways distal to this enzyme remained intact. We have previously shown that IFN-inducible enzyme activities, including double-stranded RNA-dependent eIF2 kinase and 2',5'-oligoadenylate synthetase, are normal in IRB cells. The finding that the induction of multiple growth-related genes by several independent growth factors is inhibited in these IFN-resistant cells suggests that there is a second messenger common to both growth factor and IFN signaling pathways and that this messenger is defective in these cells.

scholarly journals BALB/c-3T3 fibroblasts resistant to growth inhibition by beta interferon exhibit aberrant platelet-derived growth factor, epidermal growth factor, and fibroblast growth factor signal transduction

1991 ◽  
Vol 11 (6) ◽  
pp. 3148-3154
Author(s):  
L J Mundschau ◽  
D V Faller
Keyword(s):  
Signal Transduction ◽  
Growth Factors ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Signal Transduction Pathway ◽  
Platelet Derived Growth Factor ◽  
Fibroblast Growth ◽  
Transduction Pathway ◽  
Double Stranded Rna ◽  
Epidermal Growth

Several lines of evidence now exist to suggest an interaction between the platelet-derived growth factor (PDGF) growth-stimulatory signal transduction pathway and the beta interferon (IFN-beta) growth-inhibitory signal transduction pathway. The most direct examples are inhibition of PDGF-mediated gene induction and mitogenesis by IFN-beta and the effects of activators and inhibitors of the IFN-inducible double-stranded RNA-dependent eIF2 kinase on expression of PDGF-inducible genes. To further investigate the nature of this PDGF/IFN-beta interaction, we selected BALB/c-3T3 cells for resistance to growth inhibition by IFN-beta and analyzed the phenotypes of resulting clonal lines (called IRB cells) with respect to PDGF signal transduction. Although selected only for IFN resistance, the IRB cells were found to be defective for induction of growth-related genes c-fos, c-myc and JE in response to PDGF. This block to signal transduction was not due to loss or inactivation of PDGF receptors, as immunoprecipitation of PDGF receptors with antiphosphotyrosine antibodies showed them to be present at equal levels in the BALB/c-3T3 and IRB cells and to be autophosphorylated normally in response to PDGF. Furthermore, treatment with other peptide growth factors (PDGF-AA, fibroblast growth factor, and epidermal growth factor) also failed to induce c-fos, c-myc, or JE expression in IRB cells. All of these growth factors, however, were able to induce another early growth-related gene, Egr-1. The block to signaling was not due to a defect in inositol phosphate metabolism, as PDGF treatment induced normal calcium mobilization and phosphotidylinositol-3-kinase activation in these cells. Activation of protein kinase C by phorbol esters did induce c-fos, c-myc, and JE in IRB cells, indicating that signalling pathways distal to this enzyme remained intact. We have previously shown that IFN-inducible enzyme activities, including double-stranded RNA-dependent eIF2 kinase and 2',5'-oligoadenylate synthetase, are normal in IRB cells. The finding that the induction of multiple growth-related genes by several independent growth factors is inhibited in these IFN-resistant cells suggests that there is a second messenger common to both growth factor and IFN signaling pathways and that this messenger is defective in these cells.

Accumulation of inositol phosphates in low-passage human meningioma cells following treatment with epidermal growth factor

1994 ◽  
Vol 80 (5) ◽  
pp. 890-896 ◽  
Author(s):  
Tomoki Todo ◽  
Rudolf Fahlbusch
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Human Meningioma ◽  
Phosphate Accumulation ◽  
Phospholipid Hydrolysis ◽  
Inositol Phosphate Accumulation ◽  
Epidermal Growth ◽  
Inositol Phospholipid

✓ In order to elucidate some of the signal transduction processes in human meningioma cells, the authors studied the effect of epidermal growth factor (EGF) and bromocriptine on inositol phospholipid hydrolysis, using low-passage human meningioma cells in culture. Epidermal growth factor is a well-studied mitogenic factor for meningioma cells, whereas bromocriptine is known to have an inhibitory effect on meningioma cell proliferation. The addition of EGF to meningioma cells caused stimulation of inositol phosphate accumulation in a dose-dependent manner at 60 minutes posttreatment, with the maximum effect (120% to 167% of control) achieved at a concentration of 10 ng/ml. Extraction of separate inositol phosphates revealed that inositol monophosphate (IP1) and inositol bisphosphate (IP2), but not inositol trisphosphate (IP3), accounted for the increase at 60 minutes. Kinetic analysis of EGF-stimulated inositol phospholipid hydrolysis showed that a sharp and transient increase in IP3 from 5 to 12 minutes post-EGF and a transient but more gradual increase in IP2 from 2 to 12 minutes post-EGF were followed by a gradual and steady increase in IP1, which was significantly greater than control after 5 minutes. On the other hand, long-term studies showed a down-regulation of inositol phosphate accumulation (a 64% decrease vs. control) after 7 days of treatment with EGF (10 ng/ml). Bromocriptine (5 µM) exhibited no significant effect on inositol phosphate accumulation at 60 minutes in four of five meningiomas studied. However, of two meningiomas studied with bromocriptine in combination with EGF, both showed a significant additive increase in inositol phosphate accumulation compared to those treated with EGF alone. The results suggest a close involvement of inositol phospholipid turnover in human meningioma cells in response to mitogenic stimulation by EGF.

scholarly journals Epidermal-growth-factor-induced formation of inositol phosphates in human A431 cells. Differences from the effect of bradykinin

1988 ◽  
Vol 252 (3) ◽  
pp. 857-863 ◽  
Author(s):  
B C Tilly ◽  
P A van Paridon ◽  
I Verlaan ◽  
S W de Laat ◽  
W H Moolenaar
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Cell System ◽  
Ionophore A23187 ◽  
A431 Cells ◽  
Inositol Phosphate Metabolism ◽  
Absolute Requirement ◽  
Epidermal Growth

In human A431 epidermoid carcinoma cells, epidermal growth factor (EGF) rapidly stimulates the breakdown of inositol phospholipids and raises cytoplasmic free [Ca2+]. In this paper, we investigate the action of EGF on inositol phosphate metabolism, and we compare it with the previously described effects of bradykinin on the same cell system [Tilly, van Paridon, Verlaan, Wirtz, de Laat & Moolenaar (1987) Biochem. J. 244, 129-135]. In cells prelabelled with [3H]inositol, EGF slowly but persistently (for at least 30 min) stimulates the formation of [3H]inositol phosphates, whereas bradykinin causes an immediate but transient release of inositol phosphates, which lasts for only a few minutes. The EGF effect is additive to bradykinin stimulation and does not require extracellular Ca2+. In contrast, inositol phosphate formation induced by Ca2+-ionophore A23187 has an absolute requirement for external Ca2+. Treatment of the cells with 12-O-tetradecanoylphorbol 13-acetate completely abolishes the response to EGF and to sub-optimal doses of bradykinin, suggesting a negative-feedback function of protein kinase C. Pretreatment of the cells with pertussis toxin has no effect on inositol phosphate formation induced by either EGF or bradykinin. Unlike bradykinin, EGF stimulates very little accumulation of inositol 1,4,5-trisphosphate, with only a small and rather variable release of Ca2+ from intracellular stores. EGF rapidly but transiently increases inositol 1,3,4-trisphosphate and 1,3,4,5-tetrakisphosphate, but the effects are much smaller than those of bradykinin. In addition, EGF increases both inositol mono- and bis-phosphate. At 10 min after EGF addition, inositol monophosphate, unlike the other inositol phosphates, is still increasing. It is concluded that the EGF-dependent pattern of stimulation is different from that observed in bradykinin-stimulated A431 cells, suggesting that there are separate mechanisms of inositol-lipid hydrolysis involved.

scholarly journals Signal transduction by epidermal growth factor occurs through the subclass of high affinity receptors.

1989 ◽  
Vol 109 (5) ◽  
pp. 2495-2507 ◽  
Author(s):  
L H Defize ◽  
J Boonstra ◽  
J Meisenhelder ◽  
W Kruijer ◽  
L G Tertoolen ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cellular Response ◽  
Inositol Phosphate ◽  
Receptor Protein ◽  
Binding Studies ◽  
Intact Cells ◽  
High Affinity ◽  
Epidermal Growth

Many cell types display two classes of epidermal growth factor receptor (EGFR) as judged from EGF binding studies; i.e., a major class of low affinity EGFR and a minor class of high affinity EGFR. We have studied their respective contribution to the cascade of events elicited by EGF in human A431 carcinoma cells, using anti-EGFR mAb 2E9. This antibody specifically blocks EGF binding to low affinity EGFR, without activating receptors in intact cells, and thus enables us to study the effects of exclusive EGF binding to high affinity EGFR. We show that blocking of low affinity EGFR by mAb 2E9 has almost no effect on the activation of the receptor protein-tyrosine kinase by EGF, suggesting that EGFR kinase activation occurs exclusively through the subclass of high affinity EGFR (5-10%). In addition, we provide evidence that high affinity EGFR exists both in monomeric and dimeric forms, and that cross-phosphorylation of low affinity EGFR by high affinity EGFR may take place in dimers of both receptor types. We demonstrate that the following early cellular response to EGF are also unimpaired in the presence of mAb 2E9: (a) inositol phosphate production, (b) release of Ca2+ from intracellular stores, (c) rise in intracellular pH, (d) phosphorylation of EGF on threonine residue 654, (e) induction of c-fos gene expression, and (f) alteration in cell morphology. As possible nonspecific side effects, we observed that the EGF induced Ca2+ influx and fluid-phase pinocytosis were inhibited in A431 cells in the presence of mAb 2E9. We conclude, therefore, that the activation of the EGFR signal transduction cascade can occur completely through exclusive binding of EGF to the subclass of high affinity EGFR.

Insulin and epidermal growth factor are growth factors for isolated porcine thyroid follicles

1985 ◽  
Vol 110 (1_Suppla) ◽  
pp. S74
Author(s):  
R. GÄRTNER ◽  
W. GREIL ◽  
R. DEMHARTER ◽  
K. HORN
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Epidermal Growth
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