scholarly journals Characterization of the intracellular signalling pathways that underlie growth-factor-stimulated glucose transport in Xenopus oocytes: evidence for ras- and rho-dependent pathways of phosphatidylinositol 3-kinase activation

1997 ◽  
Vol 325 (3) ◽  
pp. 637-643 ◽  
Author(s):  
Fiona J. THOMSON ◽  
Thomas J. JESS ◽  
Colin MOYES ◽  
Robin PLEVIN ◽  
Gwyn W. GOULD
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
G Protein ◽  
Glucose Transport ◽  
Dominant Negative ◽  
Signalling Pathways ◽  
Phosphatidylinositol 3 Kinase ◽  
Igf I ◽  
G Protein Coupled ◽  
Phosphatidylinositol 3

The stimulation of glucose transport is one of the early cellular responses to growth factors and is essential for cell proliferation, yet the molecular processes that underlie this response are poorly defined. The aim of this study was to characterize the role of the low-molecular-mass G-proteins, Ras and Rho, and their downstream targets, Raf protein kinase and phosphatidylinositol 3-kinase, in the regulation of glucose transport in Xenopusoocytes by two distinct growth-factor receptors: the insulin-like growth factor I (IGF-I) tyrosine kinase receptor and the heterotrimeric G-protein-coupled lysophosphatidic acid (LPA) receptor. Microinjection of a neutralizing anti-Ras antibody partially blocked IGF-I-stimulated deoxyglucose uptake but was without effect on LPA-stimulated deoxyglucose uptake. In contrast, microinjection of the C3 coenzyme of botulinum toxin, which selectively ADP-ribosylates and inactivates Rho, inhibited LPA-stimulated, but not IGF-I-stimulated, deoxyglucose uptake. Similarly, LPA- but not IGF-I-stimulated deoxyglucose uptake was attenuated in oocytes expressing a dominant negative rhoconstruct. Cells expressing a dominant negative mutant of Raf protein kinase exhibited markedly reduced sensitivity to both LPA and IGF-I, consistent with a role for endogenous Raf in glucose uptake by both growth factors. Furthermore, expression of a constitutively activated form of raf-1 resulted in a growth-factor-independent increase in deoxyglucose uptake. Measurements of phosphatidylinositol 3-kinase activity in microinjected cells support the hypothesis that the IGF-I receptor stimulates glucose transport by a Ras-dependent activation of phosphatidylinositol 3-kinase, whereas the G-protein-coupled LPA receptor controls this response by a pathway that involves Rho-dependent activation of a distinct phosphatidylinositol 3-kinase. Thus we provide evidence for clear differences in the signalling pathways that control glucose transport by G-protein-coupled and tyrosine kinase growth-factor receptors. Furthermore this is the first demonstration that active Rho is involved in the signalling pathways that regulate glucose uptake in response to some growth factors.

scholarly journals Insulin Growth Factor-I and Epidermal Growth Factor Receptors Recruit Distinct Upstream Signaling Molecules to Enhance AKT Activation in Mammary Epithelial Cells

Endocrinology ◽  
2006 ◽  
Vol 147 (12) ◽  
pp. 6027-6035 ◽  
Author(s):  
Jodie M. Fleming ◽  
Gwenaëlle Desury ◽  
Tiffany A. Polanco ◽  
Wendie S. Cohick
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Dna Synthesis ◽  
Egf Receptor ◽  
Mammary Epithelial ◽  
Insulin Receptor Substrate ◽  
Phosphatidylinositol 3 Kinase ◽  
Mapk Activation ◽  
Igf I ◽  
Epidermal Growth

IGF-I and epidermal growth factor (EGF) stimulate both normal mammary epithelial cell (MEC) growth and tumorigenesis. Whereas both growth factors increase DNA synthesis in MECs, how they evoke a greater response in combination when they activate similar signaling pathways remains unknown. In the present study, we investigated the signaling pathways by which these mitogens act in concert to increase DNA synthesis. Only EGF activated the MAPK pathway, and no further increase in MAPK activation was observed when both mitogens were added together. Both growth factors activated the phosphatidylinositol-3 kinase pathway, and simultaneous treatment enhanced phosphorylation of both AKT and its downstream target, p70S6K. The enhanced activation of AKT was observed at multiple time points (5 and 15 min) and growth factor concentrations (2.5–100 ng/ml). IGF-I activated AKT via insulin receptor substrate-1 and p85, the regulatory subunit of phosphatidylinositol-3 kinase. Treatment with EGF had no effect on insulin receptor substrate-1; however, it activated the EGF receptor, SHC, and c-Src. EGF treatment caused the association of SHC with Grb2 and Gab2 with phospho-SHC, phospho-Gab1, Grb2, and p85. Interestingly, inhibition of Src activation blocked the ability of EGF, but not IGF-I, to activate AKT. This corresponded with a decrease in phosphorylation of the EGF receptor and its association with phospho-SHC as well as downstream signaling. Unexpectedly, inhibition of Src increased basal MAPK activation. This is the first study to show that EGF and IGF-I use separate upstream components within a given MEC line to enhance AKT phosphorylation, contributing to increased DNA synthesis.

scholarly journals Cytokine Stimulation Promotes Glucose Uptake via Phosphatidylinositol-3 Kinase/Akt Regulation of Glut1 Activity and Trafficking

2007 ◽  
Vol 18 (4) ◽  
pp. 1437-1446 ◽  
Author(s):  
Heather L. Wieman ◽  
Jessica A. Wofford ◽  
Jeffrey C. Rathmell
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Glycogen Synthase ◽  
Mammalian Target Of Rapamycin ◽  
Phosphatidylinositol 3 Kinase ◽  
Akt Activation ◽  
Cytokine Stimulation ◽  
Phosphatidylinositol 3

Cells require growth factors to support glucose metabolism for survival and growth. It is unclear, however, how noninsulin growth factors may regulate glucose uptake and glucose transporters. We show that the hematopoietic growth factor interleukin (IL)3, maintained the glucose transporter Glut1 on the cell surface and promoted Rab11a-dependent recycling of intracellular Glut1. IL3 required phosphatidylinositol-3 kinase activity to regulate Glut1 trafficking, and activated Akt was sufficient to maintain glucose uptake and surface Glut1 in the absence of IL3. To determine how Akt may regulate Glut1, we analyzed the role of Akt activation of mammalian target of rapamycin (mTOR)/regulatory associated protein of mTOR (RAPTOR) and inhibition of glycogen synthase kinase (GSK)3. Although Akt did not require mTOR/RAPTOR to maintain surface Glut1 levels, inhibition of mTOR/RAPTOR by rapamycin greatly diminished glucose uptake, suggesting Akt-stimulated mTOR/RAPTOR may promote Glut1 transporter activity. In contrast, inhibition of GSK3 did not affect Glut1 internalization but nevertheless maintained surface Glut1 levels in IL3-deprived cells, possibly via enhanced recycling of internalized Glut1. In addition, Akt attenuated Glut1 internalization through a GSK3-independent mechanism. These data demonstrate that intracellular trafficking of Glut1 is a regulated component of growth factor-stimulated glucose uptake and that Akt can promote Glut1 activity and recycling as well as prevent Glut1 internalization.

scholarly journals G Protein-Coupled Receptor Kinase 6 Acts as a Critical Regulator of Cytokine-Induced Hyperalgesia by Promoting Phosphatidylinositol 3-Kinase and Inhibiting p38 Signaling

2012 ◽  
Vol 18 (4) ◽  
pp. 556-564 ◽  
Author(s):  
Niels Eijkelkamp ◽  
Cobi J. Heijnen ◽  
Anibal Garza Carbajal ◽  
Hanneke L. D. M. Willemen ◽  
Huijing Wang ◽  
...  
Keyword(s):  
G Protein ◽  
Receptor Kinase ◽  
Phosphatidylinositol 3 Kinase ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled ◽  
Phosphatidylinositol 3

scholarly journals Lysophosphatidic acid stimulates glucose transport in Xenopus oocytes via a phosphatidylinositol 3′-kinase with distinct properties

1996 ◽  
Vol 316 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Fiona J. THOMSON ◽  
Colin MOYES ◽  
Pamela H. SCOTT ◽  
Robin PLEVIN ◽  
Gwyn W. GOULD
Keyword(s):  
Phosphatidic Acid ◽  
Glucose Transport ◽  
Lysophosphatidic Acid ◽  
Xenopus Oocytes ◽  
Kinase Activity ◽  
Sugar Transport ◽  
Phosphatidylinositol 3 Kinase ◽  
Marked Contrast ◽  
Igf I ◽  
Phosphatidylinositol 3

Lysophosphatidic acid (LPA) stimulated the transport of deoxyglucose into oocytes isolated from Xenopus laevis. This stimulation was accounted for entirely by an increase in the Vmax for transport. Various LPAs with different acyl groups in the sn-1 position and phosphatidic acid stimulated deoxyglucose (deGlc) transport in these cells with a rank order potency of 1-oleoyl-LPA > 1-palmitoyl-LPA > phosphatidic acid = 1-stearoyl-LPA > 1-myristoyl-LPA. The phosphatidylinositol 3´-kinase inhibitor LY294002 completely blocked LPA-stimulated deoxyglucose uptake (IC50 ~2 μM). In marked contrast, wortmannin, which can completely block both insulin-like growth factor-I (IGF-I)-stimulated deGlc uptake in oocytes and phosphatidylinositol 3´-kinase activation at concentrations as low as 20 nM [Gould, Jess, Andrews, Herbst, Plevin and Gibbs (1994) J. Biol. Chem. 269, 26622–26625], was a relatively poor inhibitor of LPA-stimulated deGlc transport, even at concentrations as high as 100 nM. We further show that LPA stimulates phosphatidylinositol 3´-kinase activity(s) that can phosphorylate both phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate, and that this stimulation is inhibited by LY294002 but is relatively insensitive to wortmannin, again in marked contrast to IGF-I-stimulated phosphatidylinositol 3´-kinase activity. Antibodies against the p85 regulatory subunit of phosphatidylinositol 3´-kinase or antiphosphotyrosine antibodies immunoprecipitated IGF-I-stimulated but not LPA-stimulated phosphatidylinositol 3´-kinase activity. We conclude that LPA stimulates glucose uptake in Xenopus oocytes by a mechanism that may involve activation of a form of phosphatidylinositol 3´-kinase that is distinguished from other isoforms by its resistance to wortmannin and by its substrate specificity. Since the LPA-activated form of phosphatidylinositol 3´-kinase is pharmacologically and immunologically distinct from that which is involved in IGF-I-stimulated glucose transport in these cells, we suggest that distinct isoforms of this enzyme are able to function with the same biological effect, at least in the regulation of sugar transport.

Oligodendrocytes and their precursors require phosphatidylinositol 3-kinase signaling for survival

Development ◽  
1996 ◽  
Vol 122 (8) ◽  
pp. 2529-2537
Author(s):  
G.S. Vemuri ◽  
F.A. McMorris
Keyword(s):  
Cell Death ◽  
Enzyme Activity ◽  
Growth Factors ◽  
Growth Factor ◽  
Cell Survival ◽  
Nuclear Dna ◽  
Apoptotic Cell ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3

Signal transduction in response to several growth factors that regulate oligodendrocyte development and survival involves the activation of phosphatidylinositol 3-kinase, which we detect in oligodendrocytes and their precursors. To investigate the role of this enzyme activity, we analyzed cell survival in cultures of oligodendrocytes treated with wortmannin or LY294002, two potent inhibitors of phosphatidylinositol 3-kinase. Cell survival was inhibited by 60–70% in these cultures within 24 hours, as quantitated by a tetrazolium staining assay for viable cells and by measurement of DNA content. Similar results were obtained with oligodendrocyte precursor cells. Nuclei of the dying cells contained fragmented DNA, as revealed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling assays, indicating that the cells were dying by apoptosis. Moreover, a significant increase in the number of cells with fragmented nuclear DNA was detected as early as 4 hours, well before any significant differences could be detected in glucose transport or cell viability. Exogenous addition of insulin-like growth factor-I, neurotrophin-3, platelet-derived growth factor, basic fibroblast growth factor, ciliary neurotrophic factor, N-acetyl cysteine, vitamin C, vitamin E, progesterone or serum did not prevent cell death in the presence of wortmannin or LY294002. These findings indicate that survival of oligodendrocytes and their precursors depends on a phosphatidylinositol 3-kinase mediated signaling pathway. Inhibition of this critical enzyme activity induces apoptotic cell death, even in the presence of exogenous growth factors or serum.

scholarly journals Phosphatidylinositol 3-kinase, protein kinase B and ribosomal S6 kinases in the stimulation of thyroid epithelial cell proliferation by cAMP and growth factors in the presence of insulin

2000 ◽  
Vol 348 (2) ◽  
pp. 351-358 ◽  
Author(s):  
Katia COULONVAL ◽  
Fabrice VANDEPUT ◽  
Rob C. STEIN ◽  
Sara C. KOZMA ◽  
Françoise LAMY ◽  
...  
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Protein Kinase ◽  
Dna Synthesis ◽  
Protein Kinase B ◽  
Phosphatidylinositol 3 Kinase ◽  
S6 Kinase ◽  
P70 S6 Kinase ◽  
Stimulation Of ◽  
Phosphatidylinositol 3

The proliferation of most normal cells depends on the co-operation of several growth factors and hormones, each with a specific role, but the key events involved in the action of each necessary stimulant remain largely uncharacterized. In the present study, the pathways involved in the mechanism(s) of co-operation have been investigated in primary cultures of dog thyroid epithelial cells. In this physiologically relevant system, thyroid stimulating hormone (TSH) acting through cAMP, epidermal growth factor (EGF) and phorbol esters (such as PMA) induce DNA synthesis. Their effect requires stimulation of the insulin-like growth factor-1 (IGF-1) receptor by either IGF-1 or insulin, which are not themselves mitogenic agents. In contrast, hepatocyte growth factor (HGF) is itself fully mitogenic. The results of the study demonstrate that cAMP, EGF, HGF and PMA stimulate p70 ribosomal S6 kinase (p70 S6 kinase). However, insulin/IGF-1 also stimulate p70 S6 kinase. Thus stimulation of p70 S6 kinase might be necessary, but is certainly not sufficient, for the induction of DNA synthesis and is not specific for any stimulated pathway. In contrast, phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase B (PKB) activation by insulin and HGF is strong and sustained, whereas it is weak and transient with EGF and absent in the presence of TSH or PMA. These findings suggest that: (i) stimulation of PI 3-kinases and/or PKB is not involved in the cAMP-dependent pathways leading to thyrocyte proliferation, or in the action of PMA, (ii) the stimulation of the PI 3-kinase/PKB pathway may account for the permissive action of insulin/IGF-1 in the proliferation of these cells, and (iii) the stimulation of this pathway by HGF may explain why this agent does not require insulin or IGF-1 for its mitogenic action.

Sign in / Sign up

Export Citation Format

Share Document