451
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Affiliation(s)
- N Divecha
- Inositide Laboratory, Babraham Institute, Cambridge, England
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452
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Kozasa T, Gilman AG. Purification of recombinant G proteins from Sf9 cells by hexahistidine tagging of associated subunits. Characterization of alpha 12 and inhibition of adenylyl cyclase by alpha z. J Biol Chem 1995; 270:1734-41. [PMID: 7829508 DOI: 10.1074/jbc.270.4.1734] [Citation(s) in RCA: 280] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A method is described for purification of G protein alpha and beta gamma subunits from Sf9 cells infected with recombinant baculoviruses. The subunit to be purified is coexpressed with an associated subunit bearing a hexahistidine tag. After adsorption of the oligomer to a Ni(2+)-containing column, the subunit to be purified is eluted specifically by promoting subunit dissociation with AIF4-. The alpha subunits of G12, Gq, Gz, and Gi1 and the beta 1 gamma 2 subunit complex were easily and efficiently purified by this method. Results was superior to established procedures in all cases. Purified alpha 12 was characterized for the first time. The protein has a slow rate of guanine nucleotide exchange (kon, GTP gamma S = 0.01 min-1) and a very slow kcat for hydrolysis of GTP (0.1-0.2 min-1). GTP gamma S (guanosine 5' -3-O- (thio)triphosphate) alpha 12 does not influence the activity of several adenylyl cyclases or phospholipases. Activated alpha z inhibits the activity of type I and type V adenylyl cyclases. It is a somewhat more potent inhibitor of type V adenylyl cyclase than is activated alpha i1.
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Affiliation(s)
- T Kozasa
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235
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453
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Rittenhouse SE. Assay for Rho-dependent phosphoinositide 3-kinase activity in platelet cytosol. Methods Enzymol 1995; 256:241-6. [PMID: 7476437 DOI: 10.1016/0076-6879(95)56028-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- S E Rittenhouse
- Jefferson Cancer Institute, Philadelphia, Pennsylvania 19107, USA
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454
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Stack JH, Emr SD. Vps34p required for yeast vacuolar protein sorting is a multiple specificity kinase that exhibits both protein kinase and phosphatidylinositol-specific PI 3-kinase activities. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)31729-0] [Citation(s) in RCA: 167] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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455
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Wortmannin inhibits mitogen-activated protein kinase activation induced by platelet-activating factor in guinea pig neutrophils. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)43839-2] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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456
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Leyva-Cobián F, Carrasco-Marín E. Participation of intracellular oxidative pathways in antigen processing by dendritic cells, B cells and macrophages. Immunol Lett 1994; 43:29-37. [PMID: 7737687 DOI: 10.1016/0165-2478(94)00146-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The antigen presentation abilities of antigen presenting cells (APC) from different lineages [mainly macrophages (M phi), B cells and dendritic cells (DC)] were compared. In this review we focus on the participation of intracellular oxidative mechanisms in intracellular degradation of protein antigens: an aspect that is often neglected when the issue of antigen processing is considered. Special emphasis is given to recent findings from our laboratory indicating that in addition to a lysosomal proteolytic step being present in all APC, a previous or simultaneous oxidative step is operative in some APC (M phi) but absent or less important in others (B cells, DC).
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Affiliation(s)
- F Leyva-Cobián
- Servicio de Inmunología, Hospital Universitario Marqués de Valdecilla, Santander, Spain
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457
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Tsukada S, Simon MI, Witte ON, Katz A. Binding of beta gamma subunits of heterotrimeric G proteins to the PH domain of Bruton tyrosine kinase. Proc Natl Acad Sci U S A 1994; 91:11256-60. [PMID: 7972043 PMCID: PMC45206 DOI: 10.1073/pnas.91.23.11256] [Citation(s) in RCA: 190] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Bruton tyrosine kinase (Btk) has been implicated as the defective gene in both human and murine B-cell deficiencies. The identification of molecules that interact with Btk may shed light on critical processes in lymphocyte development. The N-terminal unique region of Btk contains a pleckstrin homology domain. This domain is found in a broad array of signaling molecules and implicated to function in protein-protein interactions. By using an in vitro binding assay and an in vivo competition assay, the pleckstrin homology domain of Btk was shown to interact with the beta gamma dimer of heterotrimeric guanine nucleotide-binding proteins (G proteins). A highly conserved tryptophan residue in subdomain 6 of the pleckstrin homology domain was shown to play a critical role in the binding. The interaction of Btk with beta gamma suggests the existence of a unique connection between cytoplasmic tyrosine kinases and G proteins in cellular signal transduction.
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Affiliation(s)
- S Tsukada
- Department of Microbiology and Molecular Genetics, University of California, Los Angeles 90024-1662
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458
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Chong LD, Traynor-Kaplan A, Bokoch GM, Schwartz MA. The small GTP-binding protein Rho regulates a phosphatidylinositol 4-phosphate 5-kinase in mammalian cells. Cell 1994; 79:507-13. [PMID: 7954816 DOI: 10.1016/0092-8674(94)90259-3] [Citation(s) in RCA: 550] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Integrin-mediated adhesion is known to stimulate production of phosphatidylinositol 4,5-bisphosphate (4,5-PIP2) and increase 4,5-PIP2 hydrolysis in response to platelet-derived growth factor (PDGF). We now show that treatment of cells with lovastatin, which inhibits modification of small GTP-binding proteins, reduced PIP2 levels and decreased calcium mobilization in response to PDGF and thrombin. In cell lysates, GTP gamma S stimulated PIP 5-kinase activity, and this effect was blocked by botulinum C3 exoenzyme, suggesting that Rho was responsible. GTP-bound recombinant Rho stimulated PIP 5-kinase activity, whereas GDP-Rho was much less potent and GTP-bound Rac was ineffective. Microinjected botulinum C3 exoenzyme caused diminished calcium mobilization in response to PDGF or thrombin. Conversely, microinjection of activated Rho reversed the decrease in calcium mobilization normally seen in nonadherent cells. These data demonstrate that Rho regulates 4,5-PIP2 synthesis and, indirectly, 4,5-PIP2 hydrolysis. They also raise the possibility that PIP2 synthesis could mediate the effects of Rho on the actin cytoskeleton.
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Affiliation(s)
- L D Chong
- Department of Immunology, Scripps Research Institute, La Jolla, California 92037
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459
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Insulin receptor substrate-1 mediates phosphatidylinositol 3'-kinase and p70S6k signaling during insulin, insulin-like growth factor-1, and interleukin-4 stimulation. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)61974-5] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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460
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Hawes BE, Touhara K, Kurose H, Lefkowitz RJ, Inglese J. Determination of the G beta gamma-binding domain of phosducin. A regulatable modulator of G beta gamma signaling. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)43955-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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461
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Offermanns S, Schultz G. Complex information processing by the transmembrane signaling system involving G proteins. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1994; 350:329-38. [PMID: 7845469 DOI: 10.1007/bf00178947] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Much of the information cells receive is transduced by a membranous signaling system that uses heterotrimeric guanine nucleotide binding proteins (G proteins) to functionally couple cell surface receptors to a variety of effectors. During recent years it has been shown that receptors, G protein alpha, beta and gamma subunits as well as effectors involved in this signaling system exhibit a remarkable structural diversity and that the interactions of these components display a bewildering complexity. Even though many questions remain to be answered, it is becoming obvious that G proteins form the basis of a complex membranous signaling network which allows the cell to coordinate and to process incoming signals already on the level of the plasma membrane.
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Affiliation(s)
- S Offermanns
- Institut für Pharmakologie, Freie Universität Berlin, Germany
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462
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463
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Whatmore J, Cronin P, Cockcroft S. ARF1-regulated phospholipase D in human neutrophils is enhanced by PMA and MgATP. FEBS Lett 1994; 352:113-7. [PMID: 7925957 DOI: 10.1016/0014-5793(94)00930-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Human neutrophil PLD activity stimulated with GTP-gamma-S was reconstituted with recombinant ARF1 in cytosol-depleted cells. PMA-pretreatment of intact cells greatly enhanced the subsequent reconstitution of the ARF1-regulated PLD activity. This enhancement was only observed provided that the intact cells were pretreated with PMA, suggesting the stable recruitment of a cytosolic component, presumably protein kinase C, to the membranes. rARF1-reconstituted PLD activity was not dependent on MgATP, but could be considerably enhanced by MgATP. Maximal effects of MgATP were seen at 1 mM. This enhancement by MgATP could not be attributed to protein kinase C. Neomycin was found to inhibit ARF1-regulated PLD activity suggesting the requirement for polyphosphoinositides. We conclude: (i) that many of the observed effects of PMA may be dependent on the presence of the small GTP-binding protein, ARF, and (ii) polyphosphoinositides are required for ARF1-stimulated PLD activity.
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Affiliation(s)
- J Whatmore
- Department of Physiology, University College London, UK
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464
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Kodaki T, Woscholski R, Hallberg B, Rodriguez-Viciana P, Downward J, Parker PJ. The activation of phosphatidylinositol 3-kinase by Ras. Curr Biol 1994; 4:798-806. [PMID: 7820549 DOI: 10.1016/s0960-9822(00)00177-9] [Citation(s) in RCA: 255] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Activation of the mammalian phosphatidylinositol 3-kinase complex can play a critical role in transducing growth factor responses. The lipid kinase complex, which is made up of p85 alpha and p110 alpha regulatory and catalytic subunits, becomes associated with a number of activated receptor protein tyrosine kinases, but the mechanism of its activation has not yet been defined. Recent evidence indicates that Ras can bind to the p85 alpha/p110 alpha complex. We describe here the functional regulation of the mammalian phosphatidylinositol 3-kinase complex by Ras. RESULTS Expression of p110 alpha, the catalytic subunit of phosphatidylinositol 3-kinase, in the fission yeast, Schizosaccharomyces pombe, has been used to demonstrate an inhibitory effect of p85 alpha on p110 alpha activity in intact cells; inhibition did not result from a decrease in p110 alpha expression. In this cellular context, we have investigated the effect of a constitutively active mutant of Ras, v-Ras, either on p85 alpha or p110 alpha-alone, or on the p85 alpha/p110 alpha complex. In the presence of the p85 alpha/p110 alpha complex, v-Ras suppressed cell growth, but an effector-domain mutant of v-Ras did not. The growth-suppressive effect of v-Ras was not seen for any other combination of expressed proteins. The phenotype induced by v-Ras was consistent with activation of the p85 alpha/p110 alpha complex: it was sensitive to the phosphatidylinositol 3-kinase inhibitor, wortmannin, and the cells accumulated 3-phosphorylated polyphosphoinositides. Activation of purified p85 alpha/p110 alpha by purified recombinant Ras in vitro was also demonstrated. CONCLUSIONS The phosphatidylinositol 3-kinase complex, p85 alpha/p110 alpha, shows a suppressed catalytic function in vivo when compared with free p110 alpha. This complex can, however, be activated by Ras. We suggest that the phosphatidylinositol 3-kinase p85 alpha/p110 alpha complex is a downstream effector of Ras.
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Affiliation(s)
- T Kodaki
- Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, London, UK
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465
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Watson A, Katz A, Simon M. A fifth member of the mammalian G-protein beta-subunit family. Expression in brain and activation of the beta 2 isotype of phospholipase C. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31768-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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466
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467
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Balla T, Catt KJ. Phosphoinositides and calcium signaling New aspects and diverse functions in cell regulation. Trends Endocrinol Metab 1994; 5:250-5. [PMID: 18407216 DOI: 10.1016/1043-2760(94)p3084-k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Numerous circulating and locally produced hormones bind to specific cell-surface receptors and activate a variety of second-messenger pathways that evoke characteristic phenotypic responses in their target cells. One of the most ubiquitous signal transduction mechanisms is the phosphoinositide-calcium messenger system, which is activated by hormones, neurotransmitters, and growth factors. Stimulation of these receptors by their ligands causes a characteristic change in the metabolism of membrane phospholipids with production of diacylglycerol and a rapid increase in cytoplasmic Ca(2+) concentration, due to the release of stored intracellular Ca(2+) and stimulated Ca(2+) entry from the extracellular space. These intracettular signals act in concert to activate protein kinases that phosphorylate a variety of regulatory proteins. The link between phosphoinositide turnover and Ca(2+) mobilization is inositol 1,4,5-trisphosphate, the major Ca(2+)-mobilizing second messenger, which is produced from membrane phosphoinositides by activated phospholipase C enzymes. The mechanisms of ligand-regulated Ca(2+) influx and the additional regulatory role(s) of phosphoinositides and inositol phosphates are still being unfolded. This review and the following article summarize some recent developments and unsolved issues about this major signal transduction cascade that links calcium-mobilizing hormone receptors to the regulation of endocrine cell function.
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Affiliation(s)
- T Balla
- The Endocrinology and Reproduction Research Branch, National Institutes of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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468
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Abstract
Currently, a central question in biology is how signals from the cell surface modulate intracellular processes. In recent years phosphoinositides have been shown to play a key role in signal transduction. Two phosphoinositide pathways have been characterized, to date. In the canonical phosphoinositide turnover pathway, activation of phosphatidylinositol-specific phospholipase C results in the hydrolysis of phosphatidylinositol 4,5-bisphosphate and the generation of two second messengers, inositol 1,4,5-trisphosphate and diacylglycerol. The 3-phosphoinositide pathway involves protein-tyrosine kinase-mediated recruitment and activation of phosphatidylinositol 3-kinase, resulting in the production of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. The 3-phosphoinositides are not substrates of any known phospholipase C, are not components of the canonical phosphoinositide turnover pathway, and may themselves act as intracellular mediators. The 3-phosphoinositide pathway has been implicated in growth factor-dependent mitogenesis, membrane ruffling and glucose uptake. Furthermore the homology of the yeast vps34 with the mammalian phosphatidylinositol 3-kinase has suggested a role for this pathway in vesicular trafficking. In this review the different mechanisms employed by protein-tyrosine kinases to activate phosphatidylinositol 3-kinase, and its involvement in the signaling cascade initiated by tyrosine phosphorylation, are examined.
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Affiliation(s)
- R Kapeller
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
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469
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Ding J, Badwey JA. Wortmannin and 1-butanol block activation of a novel family of protein kinases in neutrophils. FEBS Lett 1994; 348:149-52. [PMID: 8034030 DOI: 10.1016/0014-5793(94)00593-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Neutrophils contain four uncharacterized protein kinases with molecular masses of ca. 69, 63, 49 and 40 kDa that are rapidly activated upon stimulation of these cells with the chemoattractant fMet-Leu-Phe [Ding, J. and Badwey, J.A. (1993) J. Biol. Chem. 268, 17326-17333]. We now report that wortmannin and 1-butanol block activation of all four of these kinases. These reagents are known to inhibit superoxide generation in neutrophils stimulated with this agonist. Wortmannin inhibits phosphatidylinositol 3-kinase and blocks activation of phospholipase D, whereas 1-butanol can reduce the generation of phosphatidate in cells by serving as a substrate for phospholipase D. These data suggest that phosphatidylinositol 3-kinase and phospholipase D may be involved in the activation of several novel protein kinases in neutrophils and that one or more of these kinases is/are involved in superoxide release.
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Affiliation(s)
- J Ding
- Boston Biomedical Research Institute, MA 02114
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470
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Thomason P, James S, Casey P, Downes C. A G-protein beta gamma-subunit-responsive phosphoinositide 3-kinase activity in human platelet cytosol. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)89418-8] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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471
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Wennström S, Hawkins P, Cooke F, Hara K, Yonezawa K, Kasuga M, Jackson T, Claesson-Welsh L, Stephens L. Activation of phosphoinositide 3-kinase is required for PDGF-stimulated membrane ruffling. Curr Biol 1994; 4:385-93. [PMID: 7922352 DOI: 10.1016/s0960-9822(00)00087-7] [Citation(s) in RCA: 376] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND There is substantial evidence that phosphoinositide 3-kinase (PI 3-kinase) is a critical component of signalling pathways used by the cell-surface receptors for a variety of mammalian growth factors and other hormones. The physiological product of this enzyme is a highly polar membrane lipid called phosphatidylinositol (3,4,5)-trisphosphate This lipid has been postulated to act as a second-messenger in cells but its putative targets are still unknown. RESULTS A particular rearrangement of actin filaments, which results in membrane ruffling, is elicited by the activation of PDGF beta-receptors expressed in cultured porcine aortic endothelial cells. We have found that this consequence of PDGF beta-receptor activation is inhibited by three independent manipulations of PI 3-kinase activity: firstly, by the deletion of tyrosine residues in the PDGF beta-receptor to which PI 3-kinase binds; secondly, by the overexpression of a mutant 85 kD PI 3-kinase regulatory subunit to which the catalytic kinase subunit cannot bind; and thirdly, by the addition of the fungal metabolite wortmannin, which is a potent inhibitor of the catalytic activity of PI 3-kinase. CONCLUSIONS These results argue strongly that phosphatidylinositol (3,4,5)-trisphosphate synthesis is required for growth-factor-stimulated membrane ruffling in porcine aortic endothelial cells, and suggest that synthesis of this lipid may be part of a signalling pathway leading to direct or indirect activation of the small GTP-binding protein Rac.
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Affiliation(s)
- S Wennström
- Ludwig Institute for Cancer Research, Uppsala Branch, Sweden
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