51
|
Baukal AJ, Balla T, Hunyady L, Hausdorff W, Guillemette G, Catt KJ. Angiotensin II and guanine nucleotides stimulate formation of inositol 1,4,5-trisphosphate and its metabolites in permeabilized adrenal glomerulosa cells. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68753-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
52
|
Gonzales RA, Crews FT. Differential regulation of phosphoinositide phosphodiesterase activity in brain membranes by guanine nucleotides and calcium. J Neurochem 1988; 50:1522-8. [PMID: 2834515 DOI: 10.1111/j.1471-4159.1988.tb03039.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have shown previously that calcium and guanine nucleotides stimulate the activity of a phosphoinositide (PI) phosphodiesterase in membranes from rat cerebral cortex and that their effects are additive. To understand further guanine nucleotide- and calcium-stimulated PI phosphodiesterase activity, we have investigated the pH sensitivity and effects of inhibitors on the two modes of stimulation. NaF stimulates PI hydrolysis in brain membranes with an EC50 of 2 mM and a maximal effect at 10 mM, suggesting that a guanine nucleotide binding protein can regulate PI phosphodiesterase. Neomycin inhibited guanylylimidodiphosphate (GppNHp)-stimulated PI phosphodiesterase activity in a concentration-dependent manner, with 90% inhibition at 0.3 mM. Neomycin was not as effective at inhibiting calcium-dependent PI hydrolysis (32% inhibition at 0.3 mM). Chloroquine also had a greater inhibitory effect against GppNHp-stimulated PI phosphodiesterase activity compared to calcium-dependent activity. Guanine nucleotide- and NaF-dependent activations of PI phosphodiesterase were strongly pH-dependent, with greatest stimulation observed at pH 5-6 and inhibition at more alkaline pH. Calcium-stimulated PI hydrolysis was not as sensitive to changes in pH and had a peak of activity at pH 9. Our findings of different pH optima and differential sensitivity to inhibitors suggest that calcium and guanine nucleotides may regulate PI phosphodiesterase in rat cortical membranes through independent mechanisms.
Collapse
Affiliation(s)
- R A Gonzales
- Department of Pharmacology, Louisiana State University Medical Center, New Orleans 70112
| | | |
Collapse
|
53
|
Hauschildt S, Hirt W, Bessler W. Modulation of protein kinase C activity by NaF in bone marrow derived macrophages. FEBS Lett 1988; 230:121-4. [PMID: 2832211 DOI: 10.1016/0014-5793(88)80654-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Stimulation of murine bone marrow derived macrophages with NaF, prelabeled with [1-14C]oleate and [3H]inositol, increased the production of inositol phosphates and the release of 1,2-[14C]diacylglycerol (DAG). Moreover, NaF also induced activation of protein kinase C. These results indicate that bone marrow derived macrophages exhibit a phosphatidyl-4,5-bisphosphate phospholipase C activity, sensitive to NaF, which might be modulated by G-proteins. Activation of protein kinase C could have been mediated by NaF-induced release of DAG.
Collapse
Affiliation(s)
- S Hauschildt
- Institut für Immunbiologie, Universität Freiburg, FRG
| | | | | |
Collapse
|
54
|
Hasegawa-Sasaki H, Lutz F, Sasaki T. Role of a guanine nucleotide-binding regulatory protein in the hydrolysis of phosphatidylinositol 4,5-bisphosphate in a human T cell line. Microbiol Immunol 1988; 32:293-304. [PMID: 2839752 DOI: 10.1111/j.1348-0421.1988.tb01389.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The CD3(T3)/antigen receptor complex appears to function by transducing an antigen signal presented by macrophages into the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. In order to find out how the CD3/antigen receptor complex regulates the hydrolysis of PtdIns(4,5)P2 to diacylglycerol and inositol trisphosphate, we investigated the possible role played by a guanine nucleotide-binding regulatory protein in PtdIns(4,5)P2 hydrolysis in a human T cell leukemia line, JURKAT. JURKAT cells were made permeable to Al3+, F-, GTP, and a nonhydrolyzable GTP analogue, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), by treatment with pseudomonal cytotoxin. In the presence of AlCl3 NaF stimulated the release of inositol phosphates in the cytotoxin-treated JURKAT cells. NaF plus AlCl3 induced increases in inositol tris-, bis-, and mono-phosphates and decreases in PtdIns(4,5)P2, phosphatidylinositol 4-phosphate, and phosphatidylinositol within 5 min after addition to the cytotoxin-treated cells at 37 C. GTP gamma S stimulated, to some extent, polyphosphoinositide hydrolysis in the cytotoxin-treated JURKAT. The cytotoxin-treated JURKAT cells retained the ability to respond to anti-Leu-4 with polyphosphoinositide hydrolysis. It has been shown that Al3+ in the presence of F- modulates the activity of various guanine nucleotide-binding regulatory proteins. Therefore, the results obtained in this study indicate that a guanine nucleotide-binding regulatory protein regulates the polyphosphoinositide breakdown in JURKAT cells by influencing phosphodiesterase activity.
Collapse
|
55
|
Nakashima S, Nagata K, Ueeda K, Nozawa Y. Stimulation of arachidonic acid release by guanine nucleotide in saponin-permeabilized neutrophils: evidence for involvement of GTP-binding protein in phospholipase A2 activation. Arch Biochem Biophys 1988; 261:375-83. [PMID: 3128172 DOI: 10.1016/0003-9861(88)90353-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Addition of a guanine nucleotide analog, guanosine 5'-O-(thiotriphosphate) (GTP gamma S)(1-100 microM) induced release of [3H]arachidonic acid from [3H]arachidonate-prelabeled rabbit neutrophils permeabilized with saponin. The chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced arachidonate release was enhanced by GTP gamma S, Ca2+, or their combination. Ca2+ alone (up to 100 microM) did not effectively stimulate lipid turnover. However, the combination of fMLP plus GTP gamma S elicited greater than additional effects in the presence of resting level of free Ca2+. The addition of 100 microM of GTP gamma S reduced the Ca2+ requirement for arachidonic acid liberation induced by fMLP. Pretreatment of neutrophils with pertussis toxin resulted in the abolition of arachidonate release and diacylglycerol formation. Neomycin (1 mM) caused no significant reduction of arachidonate release. In contrast, about 40% of GTP gamma S-induced arachidonate release was inhibited by a diacylglycerol lipase inhibitor, RHC 80267 (30 microM). These observations indicate that liberation of arachidonic acid is mediated by phospholipase A2 and also by phospholipase C/diacylglycerol lipase pathways. Fluoride, which bypasses the receptor and directly activates G proteins, induced arachidonic acid release and diacylglycerol formation. The fluoride-induced arachidonate release also appeared to be mediated by these two pathways. The loss of [3H]arachidonate was seen in phosphatidylinositol, phosphatidylcholine, and phosphatidylethanolamine. These data indicate that a G protein is involved between the binding of fMLP to its receptor and activation of phospholipase A2, and also that the arachidonic acid release is mediated by both phospholipase A2 and phospholipase C/diacylglycerol lipase.
Collapse
Affiliation(s)
- S Nakashima
- Department of Biochemistry, Gifu University School of Medicine, Japan
| | | | | | | |
Collapse
|
56
|
Crouch MF, Lapetina EG. A role for Gi in control of thrombin receptor-phospholipase C coupling in human platelets. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69080-5] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
57
|
Culty M, Davidson MM, Haslam RJ. Effects of guanosine 5'-[gamma-thio]triphosphate and thrombin on the phosphoinositide metabolism of electropermeabilized human platelets. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 171:523-33. [PMID: 2831052 DOI: 10.1111/j.1432-1033.1988.tb13821.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Incubation of human platelets with myo-[3H]inositol in a low-glucose Tyrode's solution containing MnCl2 enhanced the labelling of phosphoinositides about sevenfold and greatly facilitated the measurement of [3H]inositol phosphates formed by the activation of phospholipase C. Labelled platelets were permeabilized by high-voltage electric discharges and equilibrated at 0 degree C with ATP, Ca2+ buffers and guanine nucleotides, before incubation in the absence or presence of thrombin. Incubation of these platelets with ATP in the presence or absence of Ca2+ ions led to the conversion of [3H]phosphatidylinositol to [3H]phosphatidylinositol 4-phosphate and [3H]phosphatidylinositol 4,5-bisphosphate ([3H]PtdInsP2). At a pCa of 6, addition of 100 microM GTP[gamma S] both prevented this accumulation of [3H]PtdInsP2 and stimulated its breakdown; the formation of [3H]inositol phosphates was increased ninefold. After 5 min these comprised 70% [3H]inositol monophosphate ([3H]InsP), 28% [3H]inositol bisphosphate ([3H]InsP2) and 2% [3H]inositol trisphosphate ([3H]InsP3). In shorter incubations higher percentages of [3H]InsP2 and [3H]InsP3 were found. In the absence of added Ca2+, the formation of [3H]inositol phosphates was decreased by over 90%. Incubation of permeabilized platelets with GTP[gamma S] in the presence of 10 mM Li+ decreased the accumulation of [3H]InsP and increased that of [3H]InsP2, without affecting [3H]InsP3 levels. Addition of unlabelled InsP3 decreased the intracellular hydrolysis of exogenous [32P]InsP3 but did not trap additional [3H]InsP3. These results and the time course of [3H]inositol phosphate formation suggest that GTP[gamma S] stimulated the action of phospholipase C on a pool of [3H]phosphatidylinositol 4-phosphate that was otherwise converted to [3H]PtdInsP2 and that much less hydrolysis of [3H]phosphatidylinositol to [3H]InsP or of [3H]PtdInsP2 to [3H]InsP3 occurred. At a pCa of 6, addition of thrombin (2 units/ml) to permeabilized platelets caused small increases in the formation of [3H]InsP and [3H]InsP2. This action of thrombin was enhanced twofold by 10-100 microM GTP and much more potently by 4-40 microM GTP[gamma S]. In the presence of the latter, thrombin also increased [3H]InsP3. The total formation of [3H]inositol phosphates by permeabilized platelets incubated with thrombin and GTP[gamma S] was comparable with that observed on addition of thrombin alone to intact platelets. However, HPLC of the [3H]inositol phosphates formed indicated that about 75% of the [3H]InsP accumulating in permeabilized platelets was the 4-phosphate, whereas in intact platelets stimulated by thrombin, up to 80% was the 1-phosphate.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- M Culty
- Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada
| | | | | |
Collapse
|
58
|
Abstract
Stimulation of muscarinic receptors in dissociated embryonic chick heart cells promotes the hydrolysis of the phosphoinositides resulting in accumulation of the breakdown products inositol trisphosphate, bisphosphate, and monophosphate (InsP3, Insp2, and InsP, respectively). [3H]InsP3 and [3H]InsP2 are significantly elevated within 10 seconds of carbachol addition, while there is a lag in the accumulation of [3H]InsP. The time courses of the formation of the inositol phosphates suggest that carbachol activates a polyphosphoinositide-specific phospholipase C resulting in the formation of InsP3, which is subsequently metabolized to InsP2 and InsP. High-performance liquid chromotography analysis demonstrates the formation of both naturally occurring InsP3 isomers (Ins-1,4,5-P3 and Ins-1,3,4,-P3) and of inositol tetrakisphosphate (InsP4) as well. To investigate whether a guanine nucleotide-binding protein couples receptor stimulation to phosphoinositide (PI) hydrolysis in the heart, we developed a saponin-permeabilized cell preparation that would allow external manipulation of the intracellular guanosine triphosphate (GTP) concentration. In the permeabilized cell preparation, guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S) stimulates the accumulation of [3H]InsP, [3H]InsP2, [3H]InsP3, and [3H]InsP4. The effect of GTP gamma S is half-maximal at 1 microM and maximal above 100 microM. In contrast, GTP gamma S is ineffective in promoting PI hydrolysis in the nonpermeabilized cell except at high concentrations. Other guanine nucleotides also lead to the accumulation of [3H]InsP in the permeabilized cell, while 5'-adenylylimidodiphosphate does not. Carbachol also stimulates PI hydrolysis in the permeabilized cell preparation although it is less effective than in the intact cell.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- L G Jones
- Department of Pharmacology, University of California, San Diego, La Jolla 92093
| | | | | |
Collapse
|
59
|
Chapter 1 G proteins and transmembrane signalling. ACTA ACUST UNITED AC 1988. [DOI: 10.1016/s0167-7306(08)60656-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
60
|
Affiliation(s)
- J H Exton
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| |
Collapse
|
61
|
Lo WW, Hughes J. Specific and nonspecific effects of nucleotides on hormone-induced phosphoinositide turnover in permeabilized human pituitary tumour cells (Flow 9000). FEBS Lett 1987; 226:67-71. [PMID: 2826256 DOI: 10.1016/0014-5793(87)80552-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Previous studies have shown that agonist-induced inositol phosphate formation in the human embryonic pituitary cell line Flow 9000 is regulated by guanine nucleotides, and it is likely that a guanine nucleotide-binding protein is involved in coupling receptors to phosphoinositidase C (PIC) [(1986) Biochem.Soc.Trans. 14, 1135-1136]. We have now tested the specificity of various nucleotides in regulating PIC activity in the absence or presence of the hormone cholecystokinin (CCK-8) in saponin-permeabilized [3H]inositol-labelled Flow 9000 cells. We found that all nucleotides tested (i.e. CTP, UTP, ITP, TTP, GTP, GppNHp, GTP[S], ATP, AppNHp and ATP[S]) stimulated total [3H]inositol phosphate ([3H]IP) formation in a dose-dependent manner with similar potency and efficacy. However, only guanine nucleotides significantly enhanced CCK-8 stimulation of [3H]IP production. These results indicate a physiological role for guanine nucleotides in regulating hormone-induced phosphoinositide turnover. In addition, the effects of nucleotides on calcium-dependent PIC activity are discussed.
Collapse
Affiliation(s)
- W W Lo
- Parke-Davis Research Unit, Addenbrookes Hospital Site, Cambridge, England
| | | |
Collapse
|
62
|
Shayman JA, Morrissey JJ, Morrison AR. Islet activating protein inhibits kinin-stimulated inositol phosphate production, calcium mobilization, and prostaglandin E2 synthesis in renal papillary collecting tubule cells independent of cyclic AMP. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45494-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
63
|
Abstract
Recent evidence has suggested that receptor-mediated phosphoinositide turnover, like that of the adenylate cyclase cAMP pathway, is regulated by guanine nucleotides. It is likely that one or more guanine nucleotide-binding proteins (G-proteins) couple calcium-mobilizing receptors to the activation of phosphoinositidase C. Recent studies utilizing various bacterial toxins have strongly suggested the presence of multiple G-proteins in the regulation of receptor-phosphoinositidase C coupling in a variety of cell types.
Collapse
Affiliation(s)
- W W Lo
- Parke-Davis Research Unit, Addenbrookes Hospital Site, Cambridge, England
| | | |
Collapse
|
64
|
Katan M, Parker PJ. Purification of phosphoinositide-specific phospholipase C from a particulate fraction of bovine brain. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 168:413-8. [PMID: 2822416 DOI: 10.1111/j.1432-1033.1987.tb13435.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The coupling of various agonist receptors to the hydrolysis of phosphoinositides has generated much interest in the nature of the phospholipase C that is activated. Here we report the purification of a bovine brain phospholipase C derived from the particulate fraction. A 1000-fold purification was achieved by a combination of heparin-Sepharose, DEAE-cellulose and gel-permeation chromatography. The purified enzyme appears to be monomeric and under denaturing conditions shows a single staining major polypeptide of molecular mass 154 kDa in SDS gels. The enzyme is specific for phosphoinositides although it shows a marked preference for the polyphosphoinositides. With phosphatidylinositol 4,5-bisphosphate as substrate the enzyme expresses a specific activity of greater than 100 mumol min-1 mg-1. The phospholipase C is activated by Ca2+ (0.1-10 microM). The behaviour of this particulate enzyme is discussed in the context of a agonist-induced phosphatidylinositol hydrolysis.
Collapse
Affiliation(s)
- M Katan
- Ludwig Institute for Cancer Research, University College, London, England
| | | |
Collapse
|
65
|
Segal T, Levy J, Sharoni Y. GnRH analogs stimulate phospholipase C activity in mammary tumor membranes: modulation by GTP. Mol Cell Endocrinol 1987; 53:239-43. [PMID: 2822515 DOI: 10.1016/0303-7207(87)90179-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
An in vitro assay for phospholipase C activity was developed, employing exogenously added 32P-labelled phosphatidylinositol 4,5-bisphosphate as substrate. This enzymatic assay used to analyse the direct effect of GnRH on mammary tumors. GnRH agonists stimulate membranal phosphoinositide-specific phospholipase C activity. The increase in inositoltrisphosphate production is dose dependent, and is inhibited by the GnRH antagonist Org-30276. We took advantage of this non-cellular assay system for evaluating the role of G-binding proteins in the phosphoinositide transducing system in mammary tumors. GTP gamma S stimulates the basal and GnRH-dependent phospholipase C activity. This effect was abolished by GDP beta S. The cytosolic phospholipase C activity was also stimulated by GTP gamma S but was not affected by the hormone. These results suggest that GnRH may affect the growth of mammary tumors directly and not only through the reduction of blood gonadotropin level.
Collapse
Affiliation(s)
- T Segal
- Endocrinology Laboratory, Soroka University Hospital, Beer Sheva, Israel
| | | | | |
Collapse
|
66
|
Bojanic D, Wallace MA, Wojcikiewicz RJ, Fain JN. Guanine nucleotide and pyrophosphate activate exogenous phosphatidylinositol 4,5-bisphosphate hydrolysis in rat liver plasma membranes. Biochem Biophys Res Commun 1987; 147:1088-94. [PMID: 2822038 DOI: 10.1016/s0006-291x(87)80182-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
5'-guanylylimidodiphosphate (GppNHp) in the presence of deoxycholate, stimulated the phospholipase C-mediated hydrolysis of exogenous [3H]phosphatidylinositol 4,5-bisphosphate ([3H]PIP2) to myo-[3H]inositol 1,4,5-trisphosphate in rat liver plasma membranes. Activation was not specific for guanine nucleotides as 5'-adenylylimidodiphosphate, imidodiphosphate and pyrophosphate stimulated the enzyme with similar efficacies and potencies. Enzyme activation by GppNHp was most pronounced when [3H]PIP2 was used as substrate. No added Ca++ was required for [3H]PIP2 breakdown but hydrolysis was inhibited by divalent ion chelators. GppNHp stimulation was apparent in the presence of Ca++ or Mg++ as well as chelator concentrations that partially inhibited the enzyme, indicating that this effect was not attributed to changes in affinity of these divalent cations for the enzyme or substrate. These results suggest that guanine nucleotides can stimulate the hydrolysis of exogenous [3H]PIP2 in rat liver membranes by a non-specific effect probably due to the interaction of the diphosphate moiety with the enzyme or substrate.
Collapse
Affiliation(s)
- D Bojanic
- Department of Biochemistry, University of Tennessee, Memphis 38163
| | | | | | | |
Collapse
|
67
|
Rebecchi MJ, Rosen OM. Purification of a phosphoinositide-specific phospholipase C from bovine brain. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45237-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
|
68
|
Lo WW, Hughes J. A novel cholera toxin-sensitive G-protein (Gc) regulating receptor-mediated phosphoinositide signalling in human pituitary clonal cells. FEBS Lett 1987; 220:327-31. [PMID: 3038620 DOI: 10.1016/0014-5793(87)80840-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Recent studies have implicated that a GTP-binding protein (G-protein) is involved in the coupling of both CCK-8 and muscarinic cholinergic receptors to phosphoinositidase C (PIC) in the human embryonic pituitary cell line, Flow 9000. Pretreatment of these cells with cholera toxin, but not pertussis toxin, inhibited the stimulation of [3H]inositol phosphate production by CCK-8 and acetylcholine. These inhibitory effects of cholera toxin could not be reproduced by treating the cells with the B-subunit of cholera toxin or cAMP-generating agents such as forskolin. These data suggest the presence of a novel Gc protein which is responsible for receptor-PIC coupling in Flow 9000 cells.
Collapse
|
69
|
Calcium-independent phosphoinositide breakdown in rat basophilic leukemia cells. Evidence for an early rise in inositol 1,4,5-trisphosphate which precedes the rise in other inositol phosphates and in cytoplasmic calcium. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)60827-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
70
|
The kinetics of phosphoinositide hydrolysis in rat basophilic leukemia (RBL-2H3) cells varies with the type of IgE receptor cross-linking agent used. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)60828-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
71
|
Banno Y, Nagao S, Katada T, Nagata K, Ui M, Nozawa Y. Stimulation by GTP-binding proteins (Gi, Go) of partially purified phospholipase C activity from human platelet membranes. Biochem Biophys Res Commun 1987; 146:861-9. [PMID: 3113427 DOI: 10.1016/0006-291x(87)90610-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A phospholipase C exhibiting preferential hydrolytic activity for polyphosphoinositides was partially purified from the deoxycholate extract of human platelet membranes by Q-Sepharose and Heparin-Sepharose column chromatographies. The activity of this purified phospholipase C free of the GTP gamma S-binding activity was stimulated at a similar level by addition of purified rat brain Gi or Go. These results suggest that GTP-binding proteins may interact directly with a solubilized membrane phospholipase C to stimulate its activity.
Collapse
|
72
|
Turkey erythrocyte membranes as a model for regulation of phospholipase C by guanine nucleotides. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)48046-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
73
|
Rubin R, Thomas AP, Hoek JB. Ethanol does not stimulate guanine nucleotide-induced activation of phospholipase C in permeabilized hepatocytes. Arch Biochem Biophys 1987; 256:29-38. [PMID: 3606126 DOI: 10.1016/0003-9861(87)90422-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Guanine nucleotides are thought to mediate the interaction of the receptors for calcium-mobilizing hormones and phosphoinositide-specific phospholipase C. In the present study the characteristics of guanine nucleotide-dependent phospholipase C activation were studied in [3H]inositol-labeled permeabilized hepatocytes. The nonhydrolyzable GTP analogs guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and guanyl-5'-yl imidodiphosphate stimulated the production of inositol phosphates by phospholipase C. The effect was concentration-dependent with half-maximal and maximal stimulation occurring with 0.6 and 10 microM GTP gamma S, respectively. The guanine nucleotide-induced stimulation of phosphoinositide breakdown was selective for phosphatidylinositol (4,5)-bisphosphate over phosphatidylinositol (4)-phosphate. The individual inositol phosphates formed after maximal GTP gamma S exposure were analyzed by high-performance liquid chromatography. Inositol 1,4,5-trisphosphate was rapidly produced, followed by the formation of inositol 1,3,4,5-tetrakisphosphate and inositol 1,3,4-trisphosphate. Ethanol is known to activate hormone-sensitive phospholipase C in intact rat hepatocytes. Ethanol (0.3 M) was ineffective in altering the characteristics of GTP gamma S-stimulated phospholipase C activation, in both digitonin-treated and sonicated hepatocytes. The metabolism of the various inositol phosphate isomers was unaffected by ethanol. The findings demonstrate the potential for the use of permeabilized hepatocytes in the analysis of phospholipase C activation by guanine nucleotides. Ethanol does not activate phospholipase C by altering this process.
Collapse
|
74
|
Sasaki T, Hasegawa-Sasaki H. Activation of polyphosphoinositide phospholipase C by guanosine 5'-O-(3-thio)triphosphate and fluoroaluminate in membranes prepared from a human T cell leukemia line, JURKAT. FEBS Lett 1987; 218:87-92. [PMID: 2885225 DOI: 10.1016/0014-5793(87)81024-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Polyphosphoinositide hydrolysis was studied in membranes prepared from a human T cell leukemia line, JURKAT, prelabeled with myo-[2-3H]inositol. The formation of inositol bis- and trisphosphates was stimulated in a buffer with 110 nM free Ca2+ with a nonhydrolyzable GTP analogue, GTP gamma S, and NaF plus AlCl3 in a time- and concentration-dependent manner. GTP gamma S and NaF-AlCl3 had no significant effect on the inositol monophosphate level. AlCl3 enhanced the NaF-stimulated release of inositol polyphosphates. Optimum concentrations of NaF and AlCl3 produced 1.5-fold more inositol polyphosphates than that produced by optimum concentration of GTP gamma S. OKT3 monoclonal antibody, an antibody against the T-cell receptor complex, did not stimulate the inositol polyphosphate formation by JURKAT membranes even in the presence of GTP, although the antibody at the concentrations used markedly stimulated the hydrolysis of polyphosphoinositides in intact JURKAT cells.
Collapse
|
75
|
Biffen M, Martin BR. Polyphosphoinositide labeling in rat liver plasma membranes is reduced by preincubation with cholera toxin. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47631-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
76
|
Oberdisse E, Lapetina EG. GDP beta S enhances the activation of phospholipase C caused by thrombin in human platelets: evidence for involvement of an inhibitory GTP-binding protein. Biochem Biophys Res Commun 1987; 144:1188-96. [PMID: 3107563 DOI: 10.1016/0006-291x(87)91437-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Guanosine 5'-O-thiotriphosphate (GTP gamma S) and thrombin stimulate the activity of phospholipase C in platelets that have been permeabilized with saponin and whose inositol phospholipids have been prelabeled with [3H]inositol. Ca2+ has opposite effects on the formation of [3H]inositol phosphates induced by thrombin or GTP gamma S. While the action of GTP gamma S on the formation of [3H]inositol phosphates is inhibited by Ca2+, action of thrombin is stimulated by Ca2+. Guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), which inhibits the function of GTP-binding proteins, also inhibits the effect of GTP gamma S on phospholipase C stimulation but, surprisingly, increases the effect of thrombin. Ca2+ increases the inhibitory effect of GDP beta S on GTP gamma S activation of phospholipase C, but Ca2+ further enhances the stimulatory effect of GDP beta S on the thrombin activation of phospholipase C. This indicates that two mechanisms are responsible for the activation of phospholipase C in platelets. A GTP-binding protein is responsible for regulation of phospholipase C induced by GTP gamma S, while the effect of thrombin on the stimulation of phospholipase C is independent of GTP-binding proteins. However, the effect of thrombin may be modulated by the action of an inhibitory GTP-binding protein.
Collapse
|
77
|
Regulation by phosphatidylinositol of rat pituitary plasma membrane and endoplasmic reticulum phosphatidylinositol synthase activities. A mechanism for activation of phosphoinositide resynthesis during cell stimulation. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)48262-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
78
|
|
79
|
O'Rourke F, Zavoico GB, Smith LH, Feinstein MB. Stimulus-response coupling in a cell-free platelet membrane system. GTP-dependent release of Ca2+ by thrombin, and inhibition by pertussis toxin and a monoclonal antibody that blocks calcium release by IP3. FEBS Lett 1987; 214:176-80. [PMID: 3106084 DOI: 10.1016/0014-5793(87)80037-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The Ca2+-mobilizing action of thrombin was demonstrated in a cell-free platelet membrane system consisting of open sheets of plasma membrane plus sealed membrane vesicles that accumulate Ca2+ and release Ca2+ in response to IP3. Thrombin plus GTP, acting on plasma membrane (not vesicles), produced a soluble factor (destroyed by alkaline phosphatase) that released Ca2+ from the vesicles. This effect of thrombin/GTP was blocked by a monoclonal antibody that binds to vesicles and prevents Ca2+ release by IP3. Pertussis toxin plus NAD ADP-ribosylated plasma membrane polypeptides of 39 and 41 kDa and blocked Ca2+ release by thrombin/GTP, but not by IP3.
Collapse
|
80
|
Guillon G, Balestre MN, Mouillac B, Berrada R, Kirk CJ. Mechanisms of phospholipase C activation: a comparison with the adenylate cyclase system. Biochimie 1987; 69:351-63. [PMID: 3115315 DOI: 10.1016/0300-9084(87)90026-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Many hormones, neurotransmitters or other signaling molecules exert their biological activities through the stimulation of a specific phospholipase C. Once activated, this enzyme hydrolyzes polyphosphoinositide into inositol trisphosphate and diacylglycerol, two products known to regulate the cytosolic calcium concentration and the activity of protein kinase C, respectively. The molecular mechanisms leading to the activation of phospholipase C after the binding of the signal molecule to its specific receptor remain unclear. Yet, recent studies demonstrated that at least three molecules were implicated: the receptor, the phospholipase C and a GTP binding protein. In this review, we have summarized the properties of such systems and, more particularly, those of the vasopressin-sensitive phospholipase C present in WRK1 cells. The existence of many functional and structural analogies for the receptors which regulate adenylate cyclase activity is discussed.
Collapse
Affiliation(s)
- G Guillon
- Centre CNRS-INSERM de Pharmacologie-Endocrinologie, Montpellier
| | | | | | | | | |
Collapse
|
81
|
Rock C, Jackowski S. Thrombin- and nucleotide-activated phosphatidylinositol 4,5-bisphosphate phospholipase C in human platelet membranes. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45599-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
82
|
Epidermal growth factor stimulates the rapid accumulation of inositol (1,4,5)-trisphosphate and a rise in cytosolic calcium mobilized from intracellular stores in A431 cells. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61452-8] [Citation(s) in RCA: 145] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
83
|
Phosphatidylcholine breakdown in rat liver plasma membranes. Roles of guanine nucleotides and P2-purinergic agonists. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61370-5] [Citation(s) in RCA: 178] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
84
|
Lo T, Saul W, Beaven M. The actions of Ca2+ ionophores on rat basophilic (2H3) cells are dependent on cellular ATP and hydrolysis of inositol phospholipids. A comparison with antigen stimulation. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61323-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
85
|
Imai A, Gershengorn MC. Independent phosphatidylinositol synthesis in pituitary plasma membrane and endoplasmic reticulum. Nature 1987; 325:726-8. [PMID: 3029593 DOI: 10.1038/325726a0] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Phosphatidylinositol (PtdIns), the most abundant phosphoinositide, is the precursor of phosphatidylinositol 4-monophosphate which is converted to phosphatidylinositol 4,5-bisphosphate, the lipid hydrolysed as an early step in signal transduction by many stimuli. It is generally thought that a single enzyme in the endoplasmic reticulum, PtdIns synthase (CDP-diglyceride:myoinositol 3-phosphatidyltransferase, EC 2.7.8.11), is responsible for PtdIns synthesis and that newly synthesized PtdIns is transported to the plasma membrane by exchange proteins. Several investigators have proposed that there are two functionally distinct pools of PtdIns, one responsive to stimulation and the other not, and that the stimulus-responsive pool may be synthesized at a different site within the cell, perhaps within the plasma membrane. Indeed, it was suggested that there is PtdIns synthase activity in plasma membrane isolated from rat liver. GH3 rat pituitary tumour cells are an excellent model system to study stimulation of phosphoinositide metabolism by thyrotropin-releasing hormone (TRH). Conversion of PtdIns to polyphosphoinositides and TRH (and GTP)-activated phosphoinositide hydrolysis are known to occur in plasma membrane isolated from GH3 cells. Here we report that PtdIns synthase activity in the plasma membrane of GH3 cells is distinct from that present in the endoplasmic reticulum. The plasma membrane PtdIns synthase may be responsible for a portion of PtdIns re-synthesis that occurs during cell stimulation.
Collapse
|
86
|
Orellana S, Solski PA, Brown JH. Guanosine 5'-O-(thiotriphosphate)-dependent inositol trisphosphate formation in membranes is inhibited by phorbol ester and protein kinase C. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75684-1] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
87
|
Evans SW, Beckner SK, Farrar WL. Stimulation of specific GTP binding and hydrolysis activities in lymphocyte membrane by interleukin-2. Nature 1987; 325:166-8. [PMID: 3100964 DOI: 10.1038/325166a0] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Interleukin-2 (IL-2) is a polypeptide growth factor which stimulates the proliferation and differentiation of T lymphocytes. The receptor for IL-2 is expressed on activated T lymphocytes, cloned IL-2 dependent cells and several other cell types. Analysis of the primary structure and of immune-precipitated receptor suggests that this molecule has no intrinsic signal transduction function, unlike other growth factors. IL-2 interaction with a high affinity receptor has been shown, however, to activate the calcium/phospholipid-dependent protein kinase C (PK-C) presumably via phosphoinositide hydrolysis. Members of a family of closely related guanine nucleotide binding proteins (G proteins) regulate a diverse group of metabolic events. Two of them, Gs and Gi, stimulate and inhibit adenylate cyclase activity respectively, and other G proteins are involved in diverse signal transduction system. Another member, Go, has no known function and activation of phospholipase C has been attributed to the action of an unidentified G protein, Gp. Since it has been observed that IL-2 inhibits the catalytic activity of adenylate cyclase and that agents such as PGE2 which stimulate adenylate cyclase activity inhibit the lymphoproliferative response to IL-2, association of GTP binding proteins with IL-2 signal transduction was investigated. In this report we describe for the first time the participation of a GTP binding protein in the action of a polypeptide growth factor, interleukin-2.
Collapse
|
88
|
Graff I, Mockel J, Laurent E, Erneux C, Dumont JE. Carbachol and sodium fluoride, but not TSH, stimulate the generation of inositol phosphates in the dog thyroid. FEBS Lett 1987; 210:204-10. [PMID: 3025027 DOI: 10.1016/0014-5793(87)81338-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In dog thyroid slices prelabeled with myo-[2-3H]inositol, carbachol (10(-7)-10(-4) M) and NaF (10-20 mM) stimulated IP1, IP2 and IP3 generation. These effects did not require the presence of extracellular calcium. Atropine and PDBu inhibited the action of the cholinergic agonist. No effect of TSH (1-100 mU/ml) could be detected on PIP2 hydrolysis and IP production. These results suggest that IP3 could play a role in the metabolic actions of carbachol in the thyroid; a G-protein coupling the hormone-receptor binding to phospholipase C activation exists in the thyroid membrane; the well known TSH-induced increased PI turnover does not result in IP3 accumulation.
Collapse
|
89
|
Rodbell M. Role of GTP-binding proteins in hormone and drug action: Adenylate cyclase and other transduction processes. Drug Dev Res 1987. [DOI: 10.1002/ddr.430100403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
90
|
Imai A, Gershengorn MC. Measurement of lipid turnover in response to thyrotropin-releasing hormone. Methods Enzymol 1987; 141:100-1. [PMID: 3037241 DOI: 10.1016/0076-6879(87)41059-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
91
|
Conn PM, Huckle WR, Andrews WV, McArdle CA. The molecular mechanism of action of gonadotropin releasing hormone (GnRH) in the pituitary. RECENT PROGRESS IN HORMONE RESEARCH 1987; 43:29-68. [PMID: 2819996 DOI: 10.1016/b978-0-12-571143-2.50007-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
92
|
Magnaldo I, Talwar H, Anderson WB, Pouysségur J. Evidence for a GTP-binding protein coupling thrombin receptor to PIP2-phospholipase C in membranes of hamster fibroblasts. FEBS Lett 1987; 210:6-10. [PMID: 3026838 DOI: 10.1016/0014-5793(87)81287-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Two different methods were used to study directly alpha-thrombin modulation of polyphosphoinositide breakdown in membranes prepared from Chinese hamster lung (CHL) fibroblasts. In the first one we labelled the lipid pool by incubating the intact cells with myo-[3H]inositol prior to membrane isolation; in the other we used exogenous [3H]PIP2 with phosphatidylethanolamine (1:10) added as liposomes to freshly isolated membranes. A Ca2+-dependent PIP2 and PIP phospholipase C activity was characterized by measuring the rate of formation of inositol tris- and bisphosphate. Basal phospholipase C activity was stimulated up to 3-fold by GTP or GTP-gamma-S. Of the two mitogens, alpha-thrombin and EGF, known to stimulate DNA synthesis in Chinese hamster fibroblasts, only alpha-thrombin is a potent activator of PIP2 breakdown in intact cells. Consistent with this observation, alpha-thrombin but not EGF potentiated GTP-gamma-S-dependent phospholipase C activity in membrane preparations. These results strongly support the hypothesis that a GTP-binding protein couples alpha-thrombin receptor to PIP2 hydrolysis. Because both methods used to assay phospholipase C gave identical results, we conclude that the coupling is at the level of PIP2-phosphodiesterase activity.
Collapse
|
93
|
Majerus PW, Connolly TM, Deckmyn H, Ross TS, Bross TE, Ishii H, Bansal VS, Wilson DB. The metabolism of phosphoinositide-derived messenger molecules. Science 1986; 234:1519-26. [PMID: 3024320 DOI: 10.1126/science.3024320] [Citation(s) in RCA: 562] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The phosphoinositides are minor phospholipids present in all eukaryotic cells. They are storage forms for messenger molecules that transmit signals across the cell membrane and evoke responses to extracellular agonists. The phosphoinositides break down to liberate messenger molecules or precursors of messenger molecules. Many different compounds are formed, although the functions of only a few are understood. Recent studies elaborating the pathways for formation of products from phosphoinositides and the factors controlling their metabolism are summarized here.
Collapse
|
94
|
Deckmyn H, Tu SM, Majerus PW. Guanine nucleotides stimulate soluble phosphoinositide-specific phospholipase C in the absence of membranes. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)66602-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
95
|
Banno Y, Nakashima S, Tohmatsu T, Nozawa Y, Lapetina EG. GTP and GDP will stimulate platelet cytosolic phospholipase C independently of Ca2+. Biochem Biophys Res Commun 1986; 140:728-34. [PMID: 3096325 DOI: 10.1016/0006-291x(86)90792-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The hydrolysis of [3H]phosphatidylinositol 4,5-bisphosphate (PIP2) by cytosolic phospholipase C from human platelets was determined. Cytosolic fractions were prepared from platelets that had or had not been preactivated with thrombin. Thrombin pretreatment did not affect cytosolic phospholipase C activity. In both cytosolic fractions, phospholipase C was activated by GTP and GTP gamma S. This action is observed in the presence of 2 mM EGTA. GDP was as effective as GTP in stimulating cytosolic phospholipase C in the presence of Ca2+ or EGTA. Partially purified phospholipase C obtained from platelet cytosol is activated by GTP, but not by GTP gamma S, in the presence of 2 mM EGTA. However, in the presence of 6 microM Ca2+, both GTP and GTP gamma S stimulated the partially purified phospholipase C. Our present information indicates that GTP and GDP have a direct effect on the cytosolic phospholipase C.
Collapse
|
96
|
Wojcikiewicz RJ, Kent PA, Fain JN. Evidence that thyrotropin-releasing hormone-induced increases in GTPase activity and phosphoinositide metabolism in GH3 cells are mediated by a guanine nucleotide-binding protein other than Gs or Gi. Biochem Biophys Res Commun 1986; 138:1383-9. [PMID: 3019344 DOI: 10.1016/s0006-291x(86)80436-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Thyrotropin-releasing hormone (TRH), vasoactive intestinal polypeptide (VIP) and acetylcholine stimulated high affinity GTPase activity in GH3 cell membrane preparations. The effects of acetylcholine and VIP were blocked by pretreatment of cultured cells with pertussis toxin and cholera toxin respectively. Such pretreatment, which causes covalent modification of the guanine nucleotide-binding proteins (G-proteins) of adenylate cyclase, did not, however, block the effects of TRH on GTPase activity or phosphoinositide breakdown. These data suggest that TRH receptors interact with a G-protein discrete from those associated with regulation of adenylate cyclase activity.
Collapse
|
97
|
Studies on the hepatic calcium-mobilizing activity of aluminum fluoride and glucagon. Modulation by cAMP and phorbol myristate acetate. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67347-8] [Citation(s) in RCA: 133] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
98
|
Abstract
Phosphoinositide hydrolysis is coupled to receptor systems involved in the elevation of cytosolic Ca2+ and activation of protein kinase C. In cell-free systems, guanine nucleotides are required to transduce the effects of receptor activation to phosphoinositide breakdown. Non-hydrolyzable guanine nucleotides stimulate phosphoinositide breakdown in permeabilized cells as well as membranes prepared from salivary glands, GH3 cells, neutrophils, hepatocytes and cerebral cortical tissue. In blowfly salivary gland membranes, 5-hydroxytryptamine stimulates a guanine-nucleotide dependent breakdown of both endogenous and exogenous phosphoinositide substrate through activation of phospholipase C. These data suggest that a GTP-binding protein modulates phospholipase C activity. The identity of this GTP-binding protein has not been established but may resemble other regulatory GTP-binding proteins which have been identified as transducing proteins in a variety of receptor systems.
Collapse
|
99
|
|
100
|
Eichberg J, Berti-Mattera LN. The role of inositol phosphates in intracellular calcium mobilization. PROGRESS IN BRAIN RESEARCH 1986; 69:15-28. [PMID: 3328874 DOI: 10.1016/s0079-6123(08)61045-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|