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Exton JH. The roles of calcium and phosphoinositides in the mechanisms of alpha 1-adrenergic and other agonists. Rev Physiol Biochem Pharmacol 2005; 111:117-224. [PMID: 2906170 DOI: 10.1007/bfb0033873] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Chalecka-Franaszek E, Weems HB, Crowder AT, Cox BM, Côté TE. Immunoprecipitation of high-affinity, guanine nucleotide-sensitive, solubilized mu-opioid receptors from rat brain: coimmunoprecipitation of the G proteins G(alpha o), G(alpha i1), and G(alpha i3). J Neurochem 2000; 74:1068-78. [PMID: 10693938 DOI: 10.1046/j.1471-4159.2000.0741068.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Antibodies directed against the C-terminal and the N-terminal regions of the mu-opioid receptor were generated to identify the G proteins that coimmunoprecipitate with the mu receptor. Two fusion proteins were constructed: One contained the 50 C-terminal amino acids of the mu receptor, and the other contained 61 amino acids near the N terminus of the receptor. Antisera directed against both fusion proteins were capable of immunoprecipitating approximately 70% of solubilized rat brain mu receptors as determined by [3H][D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin ([3H]DAMGO) saturation binding. The material immunoprecipitated with both of the antisera was recognized as a broad band with a molecular mass between 60 and 75 kDa when screened in a western blot. Guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) had an EC50 of 0.4 nM in diminishing [3H]DAMGO binding to the immunoprecipitated pellet. The ratio of G proteins to mu receptors in the immunoprecipitated material was 1:1. When the material immunoprecipitated with affinity-purified antibody was screened for the presence of G protein a subunits, it was determined that G(alpha)o, G(alpha)i1, G(alpha)i3, and to a lesser extent G(alpha)i2, but not G(alpha)s or G(alpha)q11, were coimmunoprecipitated with the mu receptor. Inclusion of GTPgammaS during the immunoprecipitation process abolished the coimmunoprecipitation of G proteins.
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Affiliation(s)
- E Chalecka-Franaszek
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799, USA
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3
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Yang CM, Yo YL, Hsieh JT, Ong R. 5-Hydroxytryptamine receptor-mediated phosphoinositide hydrolysis in canine cultured tracheal smooth muscle cells. Br J Pharmacol 1994; 111:777-86. [PMID: 8019756 PMCID: PMC1910084 DOI: 10.1111/j.1476-5381.1994.tb14805.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
1. 5-Hydroxytryptamine (5-HT) has been shown to induce contraction of tracheal smooth muscle. However, the mechanisms of action of 5-HT are not known. We therefore investigated the effects of 5-HT on phospholipase C (PLC)-mediated phosphoinositide (PI) hydrolysis and its regulation in canine cultured tracheal smooth muscle cells (TSMCs) labelled with [3H]-inositol. 5-HT-induced inositol phosphates (IPs) accumulation was time- and dose-dependent with a half-maximal response (EC50) and a maximal response at 0.38 +/- 0.05 and 10 microM, respectively. 2. Ketanserin and mianserin (10 and 100 nM), 5-HT2 receptor antagonists, were equipotent in blocking the 5-HT-induced IPs accumulation with pKB values of 8.46 and 8.21, respectively. In contrast, the dose-response curves of 5-HT-induced IPs accumulation were not shifted until the concentrations of NAN-190 and metoclopramide (5-HT1A and 5-HT3 receptor antagonists, respectively) were increased up to 10 microM. 3. Pretreatment of TSMCs with pertussis toxin or cholera toxin did not inhibit the 5-HT-induced IPs accumulation, but partially inhibited the AlF(4-)-induced IPs response. 4. Stimulation of IPs accumulation by 5-HT required the presence of external Ca2+ and was blocked by EGTA. The addition of Ca2+ (3-620 nM) to digitonin-permeabilized TSMCs directly stimulated IPs accumulation. A further Ca(2+)-dependent increase in IPs accumulation was obtained by inclusion of either guanosine 5'-O-(3-thiotriphoshate) (GTP gamma S) or 5-HT. The combination of GTP gamma S and 5-HT elicited an additive effect on IPs accumulation. 5. Treatment with phorbol 12-myristate 13-acetate (PMA, 1 microM, 30 min) abolished the 5-HT-induced IPs accumulation. The concentrations of PMA that gave a half-maximal and maximal inhibition of 5-HT-induced IPs accumulation were 2.2 +/- 0.4 nM and 1 microM, n = 3, respectively. The protein kinase C (PKC) activator, 4 alpha-phorbol 12,13-didecanoate, at 1 microM, did not influence this response. The inhibitory effect of PMA was reversed by staurosporine, a PKC inhibitor, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. 6. The site of this inhibition was further investigated by examining the effect of PMA on AlF(4-)-induced IPs accumulation in canine TSMCs. AlF(4-)-stimulated IPs accumulation was inhibited by PMA treatment, suggesting that the effect of PMA is distal to the 5-HT receptor. 7. Acetylcholine-induced IPs accumulation was completely inhibited by atropine, but not affected by ketanserin or mianserin, suggesting that 5-HT-induced IPs accumulation is not due to release of acetylcholine.8. These results demonstrate that 5-HT directly stimulates PLC-mediated PI hydrolysis via a pertussis toxin- and cholera toxin-insensitive GTP binding protein in canine TSMCs and that this coupling process is negatively regulated by PKC. 5-HT2 receptors may be predominantly mediating IPs accumulation and presumably IP-induced Ca2+ release may function as the transducing mechanism for 5-HT stimulated contraction of tracheal smooth muscle.
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Affiliation(s)
- C M Yang
- Department of Pharmacology, Chang Gung Medical College, Kwei-San, Tao-Yuan, Taiwan
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4
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Yang CM, Hsia HC, Chou SP, Ong R, Hsieh JT, Luo SF. Bradykinin-stimulated phosphoinositide metabolism in cultured canine tracheal smooth muscle cells. Br J Pharmacol 1994; 111:21-8. [PMID: 8012698 PMCID: PMC1910033 DOI: 10.1111/j.1476-5381.1994.tb14018.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
1. Stimulation of bradykinin (BK) receptors coupled to phosphoinositide (PI) hydrolysis was investigated in canine cultured tracheal smooth muscle cells (TSMCs). BK, kallidin, and des-Arg9-BK, stimulated [3H]-inositol phosphates (IPs) accumulation in a dose-dependent manner with half-maximal responses (EC50) at 20 +/- 5, 13 +/- 4, and 2.3 +/- 0.7 nM, (n = 5), respectively. 2. D-Arg[Hyp3, D-Phe7]-BK and D-Arg[Hyp3, Thi5,8, D-Phe7]-BK, B2 receptor antagonists, were equipotent in blocking the BK-induced IPs accumulation with pKB = 7.1 and 7.3, respectively. 3. Short-term exposure of TSMCs to phorbol 12-myristate 13-acetate (PMA, 1 microM) attenuated BK-stimulated IPs accumulation. The concentrations of PMA that gave half-maximal and maximal inhibition of BK-induced IPs accumulation were 15 +/- 4 nM and 1 microM, n = 3, respectively. The inhibitory effect of PMA on BK-induced response was reversed by staurosporine, a protein kinase C (PKC) inhibitor, suggesting that the inhibitory effect of PMA was mediated through the activation of PKC. 4. Prolonged incubation of TSMCs with PMA for 24 h, resulted in a recovery of receptor responsiveness which may be due to down-regulation of PKC. The inactive phorbol ester, 4 alpha-phorbol 12, 13-didecanoate at 1 microM, did not inhibit this response. 5. The site of this inhibition was further investigated by examining the effect of PMA on AlF(4-)-induced IPs accumulation in canine TSMCs. AlF(4-)-stimulated IPs accumulation was inhibited by PMA treatment, suggesting that the G protein(s) can be directly activated by AlF4-, which is uncoupled from phospholipase C by PMA treatment. 6. Incubation of TSMCs in the absence of external Ca2+ or upon removal of Ca2+ by addition of EGTA, caused a decrease in IPs accumulation without changing the basal levels. Addition of Ca2+ (3-620 nM) to digitonin-permeabilized TSMCs stimulated IPs accumulation was obtained by inclusion of either guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) or BK. The combination of GTP gamma S and BK caused an additive effect on IPs accumulation.7. Pretreatment of TSMCs with cholera toxin enhanced BK-stimulated IPs accumulation, whereas there was no effect with pertussis toxin.8. These data suggest that BK-stimulated PI metabolism is mediated by the activation of BK B2 receptors coupling to a G protein which is not blocked by cholera toxin or pertussis toxin treatment and dependent on external Ca2+. The transduction mechanism of BK coupled to PI hydrolysis is sensitive to feedback regulation by PKC.
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Affiliation(s)
- C M Yang
- Department of Pharmacology, Chang Gung Medical College, Kwei-San, Tao-Yuan, Taiwan
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5
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Albert PR. Heterologous expression of G protein-linked receptors in pituitary and fibroblast cell lines. VITAMINS AND HORMONES 1994; 48:59-109. [PMID: 7941429 DOI: 10.1016/s0083-6729(08)60496-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- P R Albert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
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Cote TE, Gosse ME, Weems HB. Solubilization of high-affinity, guanine nucleotide-sensitive mu-opioid receptors from 7315c cell membranes. J Neurochem 1993; 61:973-8. [PMID: 8395567 DOI: 10.1111/j.1471-4159.1993.tb03610.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
High-affinity mu-opioid receptors have been solubilized from 7315c cell membranes. Occupancy of the membrane-associated receptors with morphine before their solubilization in the detergent 3-[(3-cholamidopropyl) dimethyl]-1-propane sulfonate was critical for stabilization of the receptor. The solubilized opioid receptor bound [3H]-etorphine with high affinity (KD = 0.304 +/- 0.06 nM; Bmax = 154 +/- 33 fmol/mg of protein). Of the membrane-associated [3H]etorphine binding sites, 40 +/- 5% were recovered in the solubilized fraction. Both mu-selective and non-selective enkephalins competed with [3H]etorphine for the solubilized binding sites; in contrast, delta- and kappa-opioid enkephalins failed to compete with [3H]etorphine for the solubilized binding sites at concentrations of < 1 microM. The mu-selective ligand [3H][D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin also bound with high affinity (KD = 0.79 nM; Bmax = 108 +/- 17 fmol/mg of protein) to the solubilized material. Of the membrane-associated [3H][D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin binding sites, 43 +/- 3% were recovered in the solubilized material. Guanosine 5'-O-(3-thiotriphosphate), GTP, and guanosine 5'-O-(2-thiodiphosphate), but not adenylylimidodiphosphate, diminished [3H][D-Ala2,N-Me-Phe4,Gly5-ol] enkephalin binding in a concentration-dependent manner. Finally, mu-opioid receptors from rat brain membranes were also solubilized in a high-affinity, guanine nucleotide-sensitive state if membrane-associated receptors were occupied with morphine before and during their solubilization with the detergent 3-[(3-cholamidopropyl)dimethyl]-1-propane sulfonate.
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Affiliation(s)
- T E Cote
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
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7
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Aragay A, Katz A, Simon M. The G alpha q and G alpha 11 proteins couple the thyrotropin-releasing hormone receptor to phospholipase C in GH3 rat pituitary cells. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)73994-5] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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8
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Paulssen EJ, Paulssen RH, Gautvik KM, Gordeladze JO. Hypothalamic hormones modulate G protein levels and second messenger responsiveness in GH3 rat pituitary tumour cells. Biochem Pharmacol 1992; 44:471-7. [PMID: 1354962 DOI: 10.1016/0006-2952(92)90438-o] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thyroliberin (TRH), vasoactive intestinal peptide (VIP) and somatostatin (SRIF) act through receptors that are coupled to guanine nucleotide-binding regulatory proteins (G proteins). Regulation of hormone action may occur at the level of G protein coupling to the receptor or effector systems. In this study we demonstrate that prolonged exposure (for up to 48 hr) of cultured rat pituitary adenoma GH3 cells to these hormones caused homologous and to some extent heterologous attenuation of the adenylyl cyclase (AC) (EC 4.6.1.1) responsiveness. In addition, TRH and SRIF diminished both TRH- and guanosine 5'-[beta gamma-imido]-triphosphate-enhanced phospholipase C (PLC) (EC 3.1.4.3) activity within the same time-course. Measurements of cells membrane levels of Gs protein alpha-subunit (Gs alpha), G(i)-1 alpha/G(i)-2 alpha, G(i)-3 alpha, G(o) alpha and G beta by immunoblotting were performed. TRH and VIP upregulated levels of all G proteins except G(o) alpha and G beta. In contrast, SRIF caused a marked reduction of G beta levels. Thus, TRH and VIP, both acting through Gs, both modulated the alpha-subunit levels of this signal transducer, whereas SRIF, which possibly acts through G(i)-2, did not change the steady state level of G(i)-2 alpha. The actions of TRH, VIP and SRIF are multifaceted at the G protein level, where modulations of subtypes not directly involved in their actions may occur. These findings emphasize the complexity expected to be found in the in vivo situation.
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Affiliation(s)
- E J Paulssen
- Institute of Medical Biochemistry, University of Oslo, Norway
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Paulssen RH, Paulssen EJ, Gautvik KM, Gordeladze JO. The thyroliberin receptor interacts directly with a stimulatory guanine-nucleotide-binding protein in the activation of adenylyl cyclase in GH3 rat pituitary tumour cells. Evidence obtained by the use of antisense RNA inhibition and immunoblocking of the stimulatory guanine-nucleotide-binding protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 204:413-8. [PMID: 1310943 DOI: 10.1111/j.1432-1033.1992.tb16651.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The thyroliberin receptor in GH3 pituitary tumour cells is known to couple to phospholipase C via a guanine-nucleotide-binding protein (G protein). Thyroliberin is postulated also to activate adenylyl cyclase, via the stimulatory G protein (Gs). In order to study this coupling, we constructed an antisense RNA expression vector that contained part of the Gs alpha-subunit cDNA clone (Gs alpha) in an inverted orientation relative to the mouse metallothionein promoter. The cDNA fragment included part of the coding region and all of the 3' non-translated region. Transient expression of Gs alpha antisense RNA in GH3 cells resulted in the specific decrease of Gs alpha mRNA levels, followed by decreased Gs alpha protein levels. Thyroliberin-elicited adenylyl cyclase activation in membrane preparations showed a reduction of up to 85%, whereas phospholipase C stimulation remained unaffected. Activation of adenylyl cyclase by vasoactive intestinal peptide was reduced by 30-40%. Investigation of the effects of thyroliberin and vasoactive intestinal peptide on adenylyl cyclase in GH3 cell membranes pretreated with antisera against Gs alpha and Gi-1 alpha/Gi-2 alpha support the results obtained by the use of the antisense technique. We conclude that thyroliberin has a bifunctional effect on GH3 cells, in activating adenylyl cyclase via Gs or a Gs-like protein in addition to the coupling to phospholipase C.
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Affiliation(s)
- R H Paulssen
- Institute of Medical Biochemistry, University of Oslo, Norway
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10
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Garibay JL, Kozasa T, Itoh H, Tsukamoto T, Matsuoka M, Kaziro Y. Analysis by mRNA levels of the expression of six G protein alpha-subunit genes in mammalian cells and tissues. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1094:193-9. [PMID: 1654117 DOI: 10.1016/0167-4889(91)90008-l] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The distribution and levels of expression of Gs alpha, Gi1 alpha, Gi2 alpha, Gi3 alpha, Go alpha, and Gx alpha mRNAs were compared by Northern blot analysis using several rat tissues and selected human and rat cell lines. Gi1 alpha, Go alpha, and Gx alpha, were detected in a limited number of tissue and cells whereas Gi2 alpha, Gi3 alpha, and Gs alpha, were expressed in all the tissues and cells tested albeit in varying amounts. The expression of these six genes appears to be differentially regulated during postnatal development of the rat brain. High expression levels particularly of Go alpha, in young rat brain may be related to the formation of neurites during differentiation of nerve cells.
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Affiliation(s)
- J L Garibay
- Institute of Medical Science, University of Tokyo, Japan
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11
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Paulssen EJ, Paulssen RH, Haugen TB, Gautvik KM, Gordeladze JO. Cell specific distribution of guanine nucleotide-binding regulatory proteins in rat pituitary tumour cell lines. Mol Cell Endocrinol 1991; 76:45-53. [PMID: 1820976 DOI: 10.1016/0303-7207(91)90258-t] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
To investigate the effects of guanine nucleotide-binding regulatory proteins (G proteins) on hormonal regulation of prolactin (PRL) synthesis and secretion, the qualitative distribution of G protein alpha-subunits and their mRNAs was studied in three functionally different pituitary tumour cell lines (GH cells) and normal rat pituitary tissue. Levels of basal and modulated adenylyl cyclase (AC) and phospholipase C (PLC) activities are also included. GH cells and pituitary tissue contained various amounts of mRNAs and protein for Gs alpha, Gi-2 alpha, Gi-3 alpha and Go alpha, while mRNA for Gi-1 alpha was only detected in normal pituitary tissue. Gz alpha/Gx alpha mRNA was expressed in all pituitary cell lines as well as in pituitary tissue. Go alpha mRNA and Gz alpha/G x alpha mRNA displayed size heterogeneity. These findings may have importance in the understanding of hormone regulation of second messenger systems.
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Affiliation(s)
- E J Paulssen
- Institute of Medical Biochemistry, University of Oslo, Norway
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12
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Satoh T, Mori M, Murakami M, Iriuchijima T, Yamada M, Kobayashi I, Kobayashi S. Recognition by anti-idiotypic anti-thyrotropin-releasing hormone (TRH) antibody of rat TRH receptors. Neuropeptides 1991; 18:121-7. [PMID: 1648676 DOI: 10.1016/0143-4179(91)90103-p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We asked whether anti-idiotypic antibodies raised against anti-TRH antibody could bind to TRH receptors in the rat anterior pituitary and brain. Six rabbits were immunized with IgG from a rabbit anti-TRH antiserum. One anti-idiotypic antibody caused strong, dose-dependent inhibition in anti-TRH antibody-binding to [125]I-TRH. This inhibition was not observed after treatment with goat anti-rabbit IgG antibody. The anti-idiotypic anti-TRH antibody significantly immunoprecipitated digitonin-solubilized pituitary TRH receptors. When eluates of digitonin-solubilized membranes which were adsorbed by either an anti-idiotypic anti-TRH IgG-, normal rabbit IgG-linked affinity column or control column were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and visualized by silver stain, only the former eluate showed two bands under nonreducing conditions; one corresponded to a molecular weight marker of 200K, the other to 100K. Western blotting analysis with an anti-idiotypic anti-TRH antiserum showed a single band of molecular weight 56K under reducing conditions. The present study indicates that one can make anti-idiotypic antibodies that specifically recognize TRH receptors.
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Affiliation(s)
- T Satoh
- First Department of Internal Medicine, Gunma University, School of Medicine, Maebashi, Japan
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13
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Twery MJ, Wong LA, Gallagher JP. Somatostatin induced hyperpolarization of septal neurons is not blocked by pertussis toxin. Eur J Pharmacol 1991; 192:287-91. [PMID: 1674473 DOI: 10.1016/0014-2999(91)90054-t] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The coupling of postsynaptic somatostatin receptors to pertussis toxin (PTX) sensitive guanine nucleotide regulatory proteins (G proteins) was investigated in dorsolateral septal nucleus (DLSN) neurons using a submerged brain slice preparation and intracellular recording techniques. Rats were pretreated with PTX i.c.v. and neuronal responsivity to somatostatin and baclofen, a selective GABAB receptor agonist, tested using a submerged brain slice preparation and intracellular recording techniques. In tissue obtained from rats pretreated with PTX (2.5 micrograms) for 2-5 days, somatostatin applied by superfusion (0.1 microM) produced membrane hyperpolarization and decreased the membrane resistance of DLSN neurons. Hyperpolarizing effects of somatostatin persisted in the presence of tetrodotoxin (0.3 microM) blocking synaptic transmission. Current-voltage relations of the somatostatin-induced, PTX-resistant hyperpolarization indicated a reversal potential close to the equilibrium potential for potassium ions. Membrane hyperpolarizations in PTX treated tissue were similar to those recorded in tissue from vehicle control or untreated rats. Hyperpolarizing responses to the selective GABAB receptor agonist baclofen, however, were blocked by the PTX treatment used in the present study. Our findings suggest that the postsynaptic inhibitory effects of somatostatin in the DLSN is not mediated by a somatostatin receptor coupled to PTX-sensitive G proteins. These G proteins, however, appear to be an essential link in the postsynaptic GABAB receptor-mediated response of DLSN neurons.
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Affiliation(s)
- M J Twery
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston
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14
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Ambudkar IS, Horn VJ, Dai YS, Baum BJ. Evidence against a role for a pertussis toxin-sensitive G protein in Ca2+ mobilization in rat parotid acinar cells. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1055:259-64. [PMID: 2124929 DOI: 10.1016/0167-4889(90)90041-b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Hormone-induced Ca2+ mobilization in rat parotid acinar cells is reportedly mediated via an as yet uncharacterized G protein. We have studied the sensitivity to pertussis toxin (PTx) of this signal transduction mechanism. When rats were treated with Ptx (1.3-1.5 micrograms per animal) for 72 h, a 41 kDa membrane protein was ADP-ribosylated. This PTx treatment regimen, also, resulted in a more than 80% block of the ability of the muscarinic agonist carbachol to inhibit beta-adrenergic receptor-stimulated parotid adenylyl cyclase activity. However, cytosolic Ca2+ levels, in response to either carbachol or AIF-4, were comparable in cells prepared from both untreated or PTx-treated rats, when incubated either in the absence or presence of extracellular Ca2+. Further, both the sensitivity of the Ca2+ response to carbachol and the ability of the agonist-sensitive intracellular Ca2+ stores to be refilled by extracellular Ca2+ were unaffected by PTx treatment. Parotid membranes also contained three low-molecular-weight GTP-binding proteins (25, 22 and 18 kDa) which were unaffected by PTx. These results show that there is only one detectable substrate in parotid membranes for a PTx-catalyzed ADP-ribosylation and that hormone-induced Ca2+ mobilization events in parotid acinar cells are not mediated via PTx-sensitive components.
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Affiliation(s)
- I S Ambudkar
- Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892
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15
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Roussel JP, Astier H. Involvement of dihydropyridine-sensitive calcium channels in the GABAA potentiation of TRH-induced TSH release. Eur J Pharmacol 1990; 190:135-45. [PMID: 1706271 DOI: 10.1016/0014-2999(90)94120-m] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effects of gamma-aminobutyric acid (GABA) and isoguvacine on the thyrotropin (TSH) secretion stimulated by thyrotropin releasing hormone (TRH), were investigated in vitro with perifused rat pituitaries. At nanomolar concentrations the two agonists induced potentiation of the TRH-induced TSH release. The potentiation was blocked by SR 95531 a specific GABAA antagonist. The isoguvacine potentiation of the TSH response to TRH failed to occur when cobalt (Co2+) was added to the perifused medium. Nifedipine completely blocked the GABA or isoguvacine potentiation of the TSH response while omega-conotoxin did not modify it. Pre-perifusion of the pituitaries with pertussis toxin did not change the TSH response to TRH but completely inhibited the isoguvacine potentiation of the response. Our results demonstrate that the GABA potentiation of TRH-induced TSH release occurring through the stimulation of GABAA receptor sites is a calcium (Ca2+)-dependent phenomenon, probably mediated by activation of dihydropyridine (DHP)-sensitive, omega-conotoxin-insensitive Ca2+ channels involving a pertussis toxin-sensitive G protein.
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Affiliation(s)
- J P Roussel
- Laboratoire de Neurobiologie Endocrinologique, UA 1197 CNRS, Université Montpellier II, France
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16
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Abstract
The receptors involved in the regulation of phospholipase C by hormones, neurotransmitters and other ligands have seven transmembrane-spanning hydrophobic regions (seven-helix motif) and no known enzymatic activity. Furthermore these receptors can be isolated as complexes with guanine nucleotide binding (G) proteins. Guanine nucleotides affect the binding of hormones that stimulate phospholipase C and it has been possible to see activation of GTPase activity in membranes upon addition of these ligands. Further indirect evidence for a Gp (p stands for phospholipase C activation) protein is the finding that in membranes agonist activation of phospholipase C requires the presence of GTP gamma S a non-hydrolyzable analog of GTP. Furthermore, fluoride is able to activate phospholipase C but its inhibition of phosphatidylinositol-4' kinase (PI-4' kinase) can interfere with efforts to demonstrate this in intact cells. There are four major isozymes of phospholipase C that have been cloned and sequenced. Recently it was found that phospholipase C-gamma as well as PI-3'-kinase are substrates for phosphorylation on tyrosine residues by the EGF and PDGF receptors. The PI-3' kinase is able to convert phosphatidylinositol 4,5-bisphosphate (PIP2) to phosphatidylinositol 3,4,5-trisphosphate (PIP3) but the function of this lipid is unknown since it is not a substrate for any known phospholipase C. While much has been learned about the structure and regulation of the phosphoinositide specific kinases and phosphodiesterase enzymes this is a relatively new field in which we can expect many advances during the next few years.
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Affiliation(s)
- J N Fain
- Department of Biochemistry, University of Tennessee, Memphis 38163
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17
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Frey EA, Gosse ME, Cote TE. Reconstitution of the solubilized mu-opioid receptor coupled to a GTP-binding protein. Eur J Pharmacol 1989; 172:347-56. [PMID: 2555207 DOI: 10.1016/0922-4106(89)90015-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A mu-opioid receptor-GTP binding protein (mu-opioid receptor-G-protein) complex from the 7315c cell was solubilized with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate) and reconstituted into phospholipid vesicles. Pretreatment of the tissue with either [3H]etorphine or morphine greatly improved recovery of the receptor and maintained it in a GTP-sensitive state. GTP sensitivity was consistent with the hypothesis that a receptor-G-protein complex had been obtained. Other evidence consistent with this hypothesis was that recovery of the solubilized, prelabelled receptor was decreased by approximately 70% by pretreatment of 7315c cells with pertussis toxin. The reconstituted receptor was mu-selective: DAGO (Tyr-D-Ala-Gly-Met-Phe- NH(CH2)2OH), but not ICI 174864 or U50488-H, displaced [3H]etorphine binding with high affinity. The affinity of the reconstituted receptor for [3H]etorphine (1.25 +/- 0.20 nM) was similar to that observed for the membrane-associated receptor (0.53 +/- 0.25 nM). GTP gamma S decreased this affinity 3-fold without changing the number of binding sites. The potencies of GTP gamma S and GTP in diminishing [3H]etorphine binding were similar in the membrane and vesicle preparations, but were 10-fold lower than the potencies observed in diminishing binding to the solubilized receptor. The ability to reconstitute a functional mu-opioid receptor-G-protein complex will facilitate further study of the structure and function of the receptor and the specific identification of the associated GTP-binding protein(s).
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Affiliation(s)
- E A Frey
- Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799
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18
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Abstract
Inositol phospholipid-specific phospholipase C is the enzyme that generates phosphoinositide-derived messenger molecules. Mammalian cells contain at least five immunologically distinct phospholipase C enzymes that appear to be separate gene products. Complete amino acid sequences of four of these isozymes have been established. The overall sequence similarity is surprisingly low for enzymes catalyzing the same chemical reaction: three of them show limited amino acid sequence similarity to each other in two narrow regions, and the fourth enzyme is completely different. The diversity in primary structure together with different regional and cellular expression of the isozymes suggests that each isozyme has a defined function in processing the physiological response of different cell types to a variety of external stimuli and that each is regulated differently.
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Affiliation(s)
- S G Rhee
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, Bethesda, MD 20892
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19
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Werling LL, McMahon PN, Cox BM. Effects of pertussis toxin on opioid regulation of catecholamine release from rat and guinea pig brain slices. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1989; 339:509-13. [PMID: 2549429 DOI: 10.1007/bf00167253] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Opioid agonists selective for mu-, delta-, and kappa-receptors are all capable of regulating the stimulated release of noradrenaline from three terminal fields (cortex, hippocampus, and cerebellum) of the noradrenergic projections from locus coeruleus in the guinea pig brain. Intracerebroventricular injections of pertussis toxin abolished the ability of a mu-selective agonist and of a delta-selective agonist to inhibit stimulated noradrenaline release, but left unaffected the concentration-related inhibition of NE release by a kappa agonist. Thus, mu- and delta-receptors have been shown to be coupled to their effector system in these noradrenergic neurons via guanyl nucleotide binding proteins (G proteins) which are sensitive to pertussis toxin, while kappa-receptors in the same neurons appear to be coupled through a different mechanism which is significantly less sensitive to pertussis toxin. In contrast to opioid receptor regulation of noradrenaline release in guinea pig hippocampus, mu-, but not delta- or kappa-agonists are capable of regulation of stimulated noradrenaline release from rat hippocampus and cortex, and kappa-, but not mu- or delta-agonists are capable of inhibiting the stimulated release of dopamine from rat striatum and cortex. Pertussis toxin injections significantly attenuated mu-agonist inhibition of noradrenaline release, but had no effect on the ability of a kappa-selective agonist to regulated dopamine release, confirming the insensitivity of the kappa-receptor-effector coupling system to pertussis toxin.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
- Animals
- Brain Chemistry/drug effects
- Catecholamines/metabolism
- Corpus Striatum/metabolism
- Dopamine/metabolism
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/pharmacology
- Guinea Pigs
- Hippocampus/drug effects
- Hippocampus/metabolism
- In Vitro Techniques
- Injections, Intraventricular
- Male
- Narcotics/pharmacology
- Pertussis Toxin
- Pyrrolidines/pharmacology
- Rats
- Rats, Inbred Strains
- Receptors, Opioid/physiology
- Receptors, Opioid, delta
- Receptors, Opioid, kappa
- Receptors, Opioid, mu
- Virulence Factors, Bordetella/administration & dosage
- Virulence Factors, Bordetella/pharmacology
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Affiliation(s)
- L L Werling
- Department of Pharmacology, Uniformed Services University, Bethesda, Maryland 20814-4799
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20
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Negishi M, Ito S, Hayaishi O. Prostaglandin E receptors in bovine adrenal medulla are coupled to adenylate cyclase via Gi and to phosphoinositide metabolism in a pertussis toxin-insensitive manner. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84940-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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21
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MARTIN THOMASFJ. Effects of TRH on Secondary Messenger Systems: Summary of Section IV. Ann N Y Acad Sci 1989. [DOI: 10.1111/j.1749-6632.1989.tb46644.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Suzuki Y, Hruska KA, Reid I, Alvarez UM, Avioli LV. Characterization of phospholipase C activity of the plasma membrane and cytosol of an osteoblast-like cell line. Am J Med Sci 1989; 297:135-44. [PMID: 2923133 DOI: 10.1097/00000441-198903000-00001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The properties of phospholipase C (PL-C) in the plasma membranes (PM) and the cytosol of osteoblast-like osteosarcoma cells, UMR-106, were analyzed to see if separate enzymes or similar enzymes were involved in signalling, transduction, and arachidonate release. The cytosolic PL-C displayed substrate affinities in the order of phosphatidylinositol (PI) greater than phosphatidylinositol-4-phosphate (PIP) or phosphatidylinoisitol-4, 5-bisphosphate (PIP2). Hydrolysis of PI, PIP, and PIP2 by cytosolic PL-C was not affected by GTP or GTP gamma S and other nucleotides. PI hydrolysis by PM and cytosolic PL-C was undetectable in the presence of 500 microM EGTA and displayed two activity plateaus at various concentrations of Ca2+. The Km for Ca2+ in the PL-C activity of the first plateau was 0.08 microM. Significant hydrolysis of PIP2 by cytosolic PL-C was observed in the absence of Ca2+. In contrast to the enzyme(s) predominant in the cytosol, the order of substrate affinities for PM PL-C was PIP2 greater than PIP greater than PI. Only PIP2 hydrolysis by PM PL-C was stimulated by both GTP and GTP gamma S in a dose-dependent manner. PIP2 hydrolysis by PL-C of the PM was not observed in the absence of Ca2+, serving to further discriminate this enzyme activity from that of the cytosol. PIP2 hydrolysis by PL-C of the PM also was biphasic in the dependence on Ca2+. At resting cytosolic Ca2+ levels, the Vmax of the high affinity activity already had been achieved. Guanine nucleotide stimulation of PIP2 hydrolysis by PM PL-C was characterized by increased maximum activity with an unchanged Km for Ca2+ or for PIP2. The pH optimum of PIP2 hydrolysis was similar between cytosolic and PM forms of PL-C. PIP2 hydrolysis with production of IP3 (PL-C activity) in UMR-106 cells treated with [2-3H]-myoinositol was stimulated by PTH, and this stimulation was not inhibited by pertussis toxin. These data suggest that UMR-106 cells possess at least two distinct PL-C activities, one predominant in the cytosol and activated by increasing cytosolic Ca2+ with PI as the substrate. The second enzyme, a GTP-activated PIP2-specific PL-C in the plasma membranes may play an important role in hormone-induced PIP2 hydrolysis mediated through guanine nucleotide regulatory proteins and may participate in the hormonal regulation of osteoblast cytosolic Ca2+ and bone remodeling functions.
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Affiliation(s)
- Y Suzuki
- Division of Bone and Mineral Diseases, Jewish Hospital of St. Louis, MO 63110
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23
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Limor R, Schvartz I, Hazum E, Ayalon D, Naor Z. Effect of guanine nucleotides on phospholipase C activity in permeabilized pituitary cells: possible involvement of an inhibitory GTP-binding protein. Biochem Biophys Res Commun 1989; 159:209-15. [PMID: 2493787 DOI: 10.1016/0006-291x(89)92424-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cultured pituitary cells prelabeled with myo-[2-3H] inositol were permeabilized by ATP4-, exposed to guanine nucleotides and resealed by Mg2+. Addition of guanosine 5'-0-(3-thio triphosphate) (GTP gamma S) to permeabilized cells, or gonadotropin releasing hormone (GnRH) to resealed cells, resulted in enhanced phospholipase C activity as determined by [3H] inositol phosphate (Ins-P) production. The effect was not additive, but the combined effect was partially inhibited by guanosine 5'-0-(2-thiodiphosphate) (GDP beta S) or by neomycin. Surprisingly, addition of GDP beta S (100-600 microM) on its own resulted in a dose-related increase in [3H]Ins-P accumulation. Several nucleoside triphosphates stimulated phospholipase C activity in permeabilized pituitary cells with the following order: UTP greater than GTP gamma S greater than ATP greater than CTP. The stimulatory effect of UTP, ATP and CTP, but not GTP gamma S or GDP beta S, could also be demonstrated in normal pituitary cells suggesting a receptor-activated mechanism. GTP and GTP gamma S decreased the affinity of GnRH binding to pituitary membranes and stimulated LH secretion in permeabilized cells. These results suggest the existence of at least two G-proteins (stimulatory and inhibitory) which are involved in phospholipase C activation and GnRH action in pituitary cells.
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Affiliation(s)
- R Limor
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
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24
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Dziarski R. Correlation between ribosylation of pertussis toxin substrates and inhibition of peptidoglycan-, muramyl dipeptide- and lipopolysaccharide-induced mitogenic stimulation in B lymphocytes. Eur J Immunol 1989; 19:125-30. [PMID: 2537732 DOI: 10.1002/eji.1830190120] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Selective inhibition by pertussis toxin (PT) of mitogenic activation of mouse B lymphocytes by bacterial mitogens (peptidoglycan and lipopolysaccharide) and muramyl dipeptide (a synthetic analog of peptidoglycan fragment) was demonstrated. Mitogenic activation of B cells by protein kinase C activators and ionomycin was insensitive to PT. Also PT did not inhibit peptidoglycan- and lipopolysaccharide-induced differentiation of B cells into Ig-secreting cells, when it was added to the cultures after the proliferative stage of the response. B lymphocyte membranes contained two major PT substrates (40 and 41 kDa). The extent of PT-mediated ADP ribosylation of these substrates correlated with the degree of PT-mediated inhibition of mitogenic stimulation of B cells. B cell stimulation by all mitogens tested was not inhibited by cholera toxin at nontoxic concentrations that are known to cause maximal increase in cAMP in B cells. Since the only known substrates for PT-mediated ADP ribosylation in mammalian cells are the alpha subunits of some G proteins, our data suggest that G proteins are present in B cell membranes and that they are involved in B cell activation induced by bacterial mitogens.
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Affiliation(s)
- R Dziarski
- Department of Microbiology and Immunology, Indiana University School of Medicine, Gary 46408
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25
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Puttfarcken PS, Cox BM. Morphine-induced desensitization and down-regulation at mu-receptors in 7315C pituitary tumor cells. Life Sci 1989; 45:1937-42. [PMID: 2557508 DOI: 10.1016/0024-3205(89)90548-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Pituitary 7315c tumor cells maintained in culture were treated with varying concentrations of morphine from 10 nM to 300 microM, for periods of five or forty-eight hours. The ability of the mu-opioid receptor agonist, DAMGO, to inhibit forskolin-stimulated adenylyl cyclase in washed membrane preparations from the treated cells was compared with its activity in membranes from cells incubated in the absence of added morphine. In the same membrane preparations, the number and affinity of mu-opioid receptors was estimated by measurements of [3H]diprenorphine binding. After 5 hr of treatment with morphine concentrations of 100 nM or higher, a significant reduction in inhibition of adenylyl cyclase by DAMGO was observed. Little further loss of agonist activity was observed when the incubations were extended to 48 hr. After 5 hr of morphine treatment, there was no change in either the number of receptors, or their affinity for [3H]diprenorphine. However, after 48 hr of morphine treatment, greater than 25% reductions in receptor number were apparent with morphine pretreatment concentrations of 10 microM or higher. These results suggest that opioid tolerance in this system is primarily associated with a reduced ability of agonist-occupied receptor to activate the effector system. Receptor down-regulation was not necessary for loss of agonist response, although a reduction in receptor number occurred after exposure to high concentrations of morphine for periods longer than 5 hr.
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Affiliation(s)
- P S Puttfarcken
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
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26
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Ohmori Y, Kuriyama K. Negative coupling of γ-aminobutyric acid (GABA)B receptor with phosphatidylinositol turnover in the brain. Neurochem Int 1989; 15:359-63. [DOI: 10.1016/0197-0186(89)90145-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/1989] [Accepted: 05/15/1989] [Indexed: 10/27/2022]
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27
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Wright M, Høgset A, Alestrøm P, Gautvik KM. A 64 kDa protein is a candidate for a thyrotropin-releasing hormone receptor in prolactin-producing rat pituitary tumor cells (GH4C1 cells). Biochem Biophys Res Commun 1988; 157:875-82. [PMID: 2849944 DOI: 10.1016/s0006-291x(88)80956-2] [Citation(s) in RCA: 5] [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
A thyrotropin-releasing hormone (TRH) binding protein of 64 kDa has been identified by covalently crosslinking [3H]TRH to GH4C1 cells by ultraviolet illumination. The crosslinkage of [3H]TRH is UV-dose dependent and is inhibited by an excess of unlabeled TRH. A 64 kDa protein is also detected on immunoblots using an antiserum raised against GH4C1 cell surface epitopes. In a closely related cell line (GH12C1) which does not bind [3H]TRH, the 64 kDa protein cannot be demonstrated by [3H]TRH crosslinking nor by immunoblotting. These findings indicate that the 64 kDa protein is a candidate for a TRH-receptor protein in GH4C1 cells.
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Affiliation(s)
- M Wright
- Institute of Medical Biochemistry, University of Oslo, Norway
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28
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Brock TA, Dennis PA, Griendling KK, Diehl TS, Davies PF. GTP gamma S loading of endothelial cells stimulates phospholipase C and uncouples ATP receptors. THE AMERICAN JOURNAL OF PHYSIOLOGY 1988; 255:C667-73. [PMID: 3056027 DOI: 10.1152/ajpcell.1988.255.5.c667] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effects of GTP gamma S, a stable GTP analogue that can activate guanine nucleotide-binding proteins, on phospholipase C activation/calcium mobilization were studied in intact cultured bovine aortic endothelial cells (BAEC). Phosphoinositide metabolism and cytosolic free Ca2+ concentration [( Ca2+]i; fura-2 fluorescence) were studied after the cells were transiently permeabilized, loaded with different guanine nucleotides, and then allowed to reseal and recover. Intracellular GTP gamma S stimulated a dose-dependent [median effective concentration (EC50) 2.5 microM] decrease in basal [3H]phosphoinositide content. Phosphatidylinositol 4,5-bisphosphate, phosphatidylinositol 4-bisphosphate, and phosphatidylinositol levels decreased to 57 +/- 9, 63 +/- 8, and 74 +/- 8% control levels, respectively, in BAEC loaded with approximately 85 microM GTP gamma S. Basal inositol trisphosphate (IP3) and [Ca2+]i were increased in GTP gamma S-loaded BAEC when compared with sham-loaded BAEC. In control BAEC, the purinergic receptor agonist ATP (100 microM) induced rapid increases in [Ca2+]i and IP3. However, BAEC that had been intracellularly loaded with GTP gamma S [median inhibitory constant (IC50) 1 microM] or 5'-guanylyl-imidodiphosphate exhibited decreased calcium mobilization in response to ATP. Ionomycin (calcium ionophore)-releasable pools of calcium were similar in sham- and GTP gamma S-loaded cells, suggesting that total intracellular calcium had not been depleted by the permeabilization protocol. The diminished calcium mobilization in response to ATP was associated with decreases in ATP-stimulated PIP2 hydrolysis and IP3 formation. In addition, GTP gamma S loading did not increase basal levels of cyclic AMP. Intracellular GDP beta S, GDP, or GTP did not inhibit ATP-stimulated increases in [Ca2+]i or IP3.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T A Brock
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts
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29
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Brock TA, Capasso EA. Thrombin and histamine activate phospholipase C in human endothelial cells via a phorbol ester-sensitive pathway. J Cell Physiol 1988; 136:54-62. [PMID: 3260903 DOI: 10.1002/jcp.1041360107] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effects of phorbol esters and synthetic diglycerides on thrombin- and histamine-stimulated increases in inositol trisphosphate (IP3) and cytosolic free calcium [( Ca2+]i) were studied in cultured human umbilical vein endothelial cells (HEC). Thrombin (0.003-3.0 U/ml) and histamine (10(-7)-10(-4) M) induced rapid increases in [Ca2+]i in suspended cells as monitored with the fluorescent calcium indicator fura-2. In [3H]myoinositol-labeled cells, both thrombin (3 U/ml)- and histamine (10(-4) M)-induced IP3 increases (195% +/- 6% and 98% +/- 4%, respectively) occurred in less than 15 sec and were temporally correlated with [Ca2+]i increases. Brief incubations (5-60 min) with different protein kinase C activators [4-beta-phorbol 12-myristate 13-acetate (1-100 nM), mezerein (100 nM), and sn-1,2 dioctanoylglycerol (0.1-10 microM)] attenuated agonist-induced increases in [Ca2+]i. These compounds also inhibited thrombin- and histamine-stimulated IP3 formation, thus suggesting a tight coupling between phospholipase C activation and calcium flux in cultured HEC. Overall, these observations suggest that the pathway linking receptors to phospholipase C stimulation in human endothelial cells is sensitive to protein kinase C activation.
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Affiliation(s)
- T A Brock
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts
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30
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Guild S, Frey EA, Pocotte SL, Kebabian JW. Adenosine 3',5'-cyclic monophosphate-mediated enhancement of calcium-evoked prolactin release from electrically permeabilised 7315c tumour cells. Br J Pharmacol 1988; 94:737-44. [PMID: 2846108 PMCID: PMC1854038 DOI: 10.1111/j.1476-5381.1988.tb11583.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
1. The 7315c tumour cell was used as a model system for the investigation of adenosine 3',5'-cyclic monophosphate (cyclic AMP)-mediated enhancement of calcium-evoked prolactin release. 2. 7315c cells were permeabilised by subjecting the cells to intense electric fields. Studies investigating the penetration of the dye ethidium bromide indicated that the cells were completely permeabilised after 2 discharges of 2000 volts and that the pores remained open for at least 30 min before beginning to reseal. These permeabilisation parameters were consistent with those which gave maximal calcium-stimulated prolactin release. 3. In the absence of calcium and in the presence of EGTA (1 mM), permeabilised 7315c cells secreted prolactin at a rate of 0.23 ng min-1 per 10(6) cells. When EGTA was replaced by 1.5 mM calcium, permeabilised cells secreted prolactin at a rate of 2.20 +/- 0.30 ng min-1 per 10(6) cells in the first 5 min of exposure. Maximal calcium-dependent prolactin secretion from permeabilised cells occurred at 37 degrees C. 4. The amount of prolactin secreted, in a 5 min incubation at 37 degrees C, from permeabilised cells depended upon the free calcium concentration in the permeabilisation medium. Calcium stimulated prolactin release from permeabilised cells in the concentration range 0.1-10 microM (half maximal = 5.8 microM). When permeabilised cells were exposed to cyclic AMP (100 microM) for 5 min prior to and during a 5 min challenge with various concentrations of calcium, the amount of prolactin secreted at each effective concentration of calcium was increased. However, cyclic AMP did not alter the potency of calcium as a stimulant of prolactin secretion. 5. The results suggest that cyclic AMP potentiates calcium-evoked secretion from 7315c cells, not by increasing the entry of calcium into the cytosol, but at a step in the secretory process, distal to calcium entry, which modulates the ability of an increase in cytosolic calcium concentration to stimulate prolactin release.
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Affiliation(s)
- S Guild
- Department of Pharmacology, University of Glasgow
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31
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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
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32
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Negishi M, Ito S, Yokohama H, Hayashi H, Katada T, Ui M, Hayaishi O. Functional reconstitution of prostaglandin E receptor from bovine adrenal medulla with guanine nucleotide binding proteins. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68728-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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33
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G-protein-mediated epidermal growth factor signal transduction in a human breast cancer cell line. Evidence for two intracellular pathways distinguishable by pertussis toxin. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68915-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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34
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Wennogle L, Wysowskyj H, Steel DJ, Petrack B. Regulation of central cholecystokinin recognition sites by guanyl nucleotides. J Neurochem 1988; 50:954-9. [PMID: 3339367 DOI: 10.1111/j.1471-4159.1988.tb03004.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Guanyl nucleotides affected the binding of radiolabeled cholecystokinin (CCK) octapeptide to rodent cortical binding sites. Micromolar quantities of a stable GTP analogue, guanylyl-imidodiphosphate (GppNp), resulted in a plateau where binding was decreased by 30%. In the presence of 25 microM GppNp, binding analysis revealed a decrease in affinity (increase in KD), without an apparent effect on the maximal number of binding sites. Ki values for CCK-related peptides shifted up to 1.6-fold. The rate of peptide association decreased by threefold, and the rapid component of peptide dissociation increased. The collective data suggest that a class of central CCK binding sites is linked to nucleotide regulatory proteins. The evidence is discussed with regard to multiple receptor populations and to possible interconversions between receptor types.
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Affiliation(s)
- L Wennogle
- Research Department, CIBA-GEIGY Corporation, Summit, NJ 07901
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35
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Griendling KK, Berk BC, Socorro L, Tsuda T, Delafontaine P, Alexander RW. Secondary signalling mechanisms in angiotensin II-stimulated vascular smooth muscle cells. Clin Exp Pharmacol Physiol 1988; 15:105-12. [PMID: 3078271 DOI: 10.1111/j.1440-1681.1988.tb01051.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1. Activation of vascular smooth muscle by angiotensin II results in the generation of two second messengers, inositol trisphosphate (IP3) and diacylglycerol (DG). 2. IP3 is responsible for mobilizing calcium from endoplasmic reticulum. This signal is transient, most likely serving to initiate calcium events leading to contraction, and is attenuated by activation of protein kinase C. 3. DG stimulates protein kinase C and ultimately Na+/H+ exchange, leading to intracellular alkalinization. Accumulation of DG/activation of protein kinase C is sustained, and may be enhanced by concurrent intracellular alkalinization. The delay in induction of the sustained response appears to be related to cellular processing of the angiotensin II-receptor complex. 4. Angiotensin II-stimulated, phospholipase C-mediated IP3 formation is also modulated by a pertussis toxin-insensitive guanine nucleotide regulatory protein. 5. The GTP binding protein, movement of the receptor-ligand complex, and the signals generated by the two second messengers, IP3 and DG, interact in a complex manner to cause an integrated response of vascular smooth muscle cells to angiotensin II stimulation.
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Affiliation(s)
- K K Griendling
- Department of Medicine, Harvard Medical School, Boston, Massachusetts
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36
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O'Dorisio MS. Neuropeptide modulation of the immune response in gut associated lymphoid tissue. Int J Neurosci 1988; 38:189-98. [PMID: 2451649 DOI: 10.3109/00207458809000497] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The neuropeptides vasoactive intestinal peptide (VIP), substance P, and somatostatin are found in high concentrations in both the central nervous system and the gastrointestinal tract. Specific high affinity receptors for VIP, substance P and somatostatin have been identified on both human and murine lymphocytes, suggesting a role for each of these neuropeptides in a neuroimmune axis. These peptides may be important modulators of mucosal immunity regulating lymphocyte proliferation and trafficking in gut associated lymphoid tissue, synthesis of IgA, and histamine release. Somatostatin antagonism of both VIP and substance P effects has been observed in the immune system. Though the mechanisms by which these neuropeptides modulate immune function have not been completely delineated, current evidence supports the hypothesis that VIP modulates immune function via cAMP dependent pathways while substance P regulation of the immune response involves phospholipid metabolism. Somatostatin inhibition of both cAMP dependent and phospholipid dependent effects has been documented in endocrine tissues. Delineation of the role of these peptide-peptide interactions in modulation of the immune response promises to be a fruitful area for further investigation.
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Affiliation(s)
- M S O'Dorisio
- Department of Pediatrics and Immunology, Ohio State University, Columbus 43205
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37
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Affiliation(s)
- J H Exton
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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Pfeuffer T, Helmreich EJ. Structural and functional relationships of guanosine triphosphate binding proteins. CURRENT TOPICS IN CELLULAR REGULATION 1988; 29:129-216. [PMID: 3135154 DOI: 10.1016/b978-0-12-152829-4.50006-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Information available at present documents the existence of three well-defined classes of guanine nucleotide binding proteins functioning as signal transducers: Gs and Gi which stimulate and inhibit adenylate cyclase, respectively, and transducin which transmits and amplifies the signal from light-activated rhodopsin to cGMP-dependent phosphodiesterase in ROS membranes. Go is a fourth member of this family. Its function is the least known among GTP binding signal transducing proteins. The family of G proteins has a number of properties in common. All are heterotrimers consisting of three subunits, alpha, beta, and gamma. Each of the subunits may be heterogeneous depending on species and tissue of origin and may be posttranslationally modified covalently. The alpha subunits vary in size from 39 to 52 kDa. The sequences for Gs alpha and transducin alpha have 42% overall homology and those of Gi alpha and Gs alpha 43%, whereas those of Gi alpha and transducin alpha have a higher degree (68%) of homology. All alpha subunits bind guanine nucleotides and are ADP-ribosylated by either pertussis toxin (Gi, transducin, Go) or cholera toxin (Gs, Gi, transducin). Thus, transducin and Gi, which have the highest degree of sequence homology, are also ADP-ribosylated by both toxins. The beta subunits have molecular weights of 36 and 35 kDa, respectively. While Gs, Gi, and Go contain a mixture of both, transducin contains only the larger (36-kDa) beta-polypeptide. The relationship of the 36- and the 35-kDa beta subunits is not defined. Although the complete sequence of the 36-kDa beta subunit of transducin has been deduced from the cDNA sequence, complete sequences of other beta subunits are not yet available so that detailed comparisons cannot be made at present. However, the proteolytic profiles of each class of the beta subunits of different G proteins are indistinguishable. The gamma subunit of bovine transducin has been completely sequenced. It has a Mr of 8400. Again complete sequences of other gamma subunits are not yet available. While the gamma subunits of Gs, Gi, and Go have identical electrophoretic mobility in SDS gels, they differ significantly in this respect from the gamma subunit of transducin. Moreover, crossover experiments point to functional differences between gamma subunits from G protein and transducin complexes. In addition, a role for beta, gamma in anchoring guanine nucleotide binding proteins to membranes has been postulated.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- T Pfeuffer
- Department of Physiological Chemistry, University of Würzburg, Federal Republic of Germany
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Purification and characterization of two immunologically distinct phosphoinositide-specific phospholipases C from bovine brain. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45235-0] [Citation(s) in RCA: 176] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Regulation of thyrotropin-releasing hormone receptor binding and phospholipase C activation by a single GTP-binding protein. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47964-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Blachier F, Malaisse WJ. Phospholipase C activation via a GTP-binding protein in tumoral islet cells stimulated by carbamylcholine. EXPERIENTIA 1987; 43:601-2. [PMID: 3036556 DOI: 10.1007/bf02126344] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Carbamylcholine and GTP act synergistically in stimulating the production of [3H]inositol-1-phosphate by digitonized tumoral islet cells (RINm5F line) prelabeled with myo-[2-3H(N)]inositol. The response to these two agents is similar to that evoked by GTP gamma S. These findings suggest that a GTP-binding regulatory protein couples the occupancy of muscarinic receptors to activation of phospholipase C in pancreatic islet cells.
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Narumiya S, Hirata M, Nanba T, Nikaido T, Taniguchi Y, Tagaya Y, Okada M, Mitsuya H, Yodoi J. Activation of interleukin-2 receptor gene by forskolin and cyclic AMP analogues. Biochem Biophys Res Commun 1987; 143:753-60. [PMID: 3032178 DOI: 10.1016/0006-291x(87)91418-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Forskolin (FK), a reversible activator of adenylate cyclase, markedly enhanced the expression of interleukin-2 receptor (IL-2-R) on a human natural killer (NK)-like cell line, YT. The FK-induced increase in IL-2-R on YT cells closely correlated with an increase in intracellular cyclic AMP (cAMP) level, and was mimicked by dibutyryl cyclic AMP (dbcAMP). FK induced both high and low affinity IL-2-R on the cells. Using a cDNA for the IL-2-R as a probe, the FK-induced IL-2-R expression was shown to be associated with an increase in IL-2-R mRNA. FK also enhanced the IL-2-R expression on a human T lymphotrophic virus I (HTLV-I) positive T-cell line (YTA-1H) and augmented the phorbol ester-induced expression of IL-2-R on HTLV-I negative T-cell lines (HSB-2 and HPB-ALL). These results suggest the possibility that the stimulation of adenylate cyclase may serve as a pathway leading to activation of the IL-2-R gene in certain types of lymphocytes.
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DeFranco AL, Gold MR, Jakway JP. B-lymphocyte signal transduction in response to anti-immunoglobulin and bacterial lipopolysaccharide. Immunol Rev 1987; 95:161-76. [PMID: 3032773 DOI: 10.1111/j.1600-065x.1987.tb00504.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Paris S, Pouysségur J. Further evidence for a phospholipase C-coupled G protein in hamster fibroblasts. Induction of inositol phosphate formation by fluoroaluminate and vanadate and inhibition by pertussis toxin. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61606-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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SORIMACHI MASARU, NISHIMURA SHIGETO, SADANO HIROYUKI. Role of guanine nucleotide regulatory protein in histamine secretion from digitonin-permeabilized rat mast cells . Biomed Res 1987. [DOI: 10.2220/biomedres.8.205] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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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.
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Jakway JP, DeFranco AL. Pertussis toxin inhibition of B cell and macrophage responses to bacterial lipopolysaccharide. Science 1986; 234:743-6. [PMID: 3095921 DOI: 10.1126/science.3095921] [Citation(s) in RCA: 110] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Lipopolysaccharide, a component of the outer membrane of Gram-negative bacteria, activates B lymphocytes and macrophages. Pertussis toxin, which inactivates several members of the G protein family of signaling components, including Gi and transducin, was found to inhibit the lipopolysaccharide-induced responses of the WEHI-231 B lymphoma cell line and the P388D1 macrophage cell line. These results, combined with the demonstration that lipopolysaccharide inhibits adenylate cyclase activity in P388D1 cells, strongly argues that lipopolysaccharide activation of cells is mediated by a Gi-like receptor-effector coupling protein.
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