Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We previously reported that transfection of antisense OBCAM (opioid-binding cell adhesion molecule) cDNA into NG108-15 neuroblastoma x glioma hybrid cells, which contain delta-opioid receptors, results in greatly reduced opioid binding (Ann, D. K., Hasegawa, J., Ko, J. L., Chen, S. T., Lee, N. M., and Loh, H. H. (1992) J. Biol. Chem. 267, 7921-7926. Here we report that these cells show altered coupling between opioid receptors and G-proteins. G-proteins were identified using cholera toxin (CTX)-induced ADP-ribosylation and antisera selective for Gi2 and Go alpha subunits. In the presence of delta-opioid agonists, CTX induced the incorporation of [32P]ADP-ribose into a 39-41-kDa protein with the same electrophoretic mobility as Gi2 and Go alpha subunits. This band, which was also a pertussis toxin (PTX) substrate, exhibited decreased CTX-induced ADP-ribosylation in membranes of cells treated chronically with D-Ala2-D-Leu5-enkephalin (DADLE). In cells transfected with antisense cDNA for OBCAM, labeling of this band was also decreased, compared with either sense-transfected or untransfected cells. DADLE inhibition of adenylyl cyclase and DADLE stimulation of GTPase were also greatly impaired in antisense cells, as well as GTP and GppNHp inhibition of basal and forskolin-stimulated adenylyl cyclase. These results provide further evidence for a role of OBCAM in opioid receptor function.
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PMID:Transfection of NG108-15 cells with antisense opioid-binding cell adhesion molecule cDNA alters opioid receptor-G-protein interaction. 839 63

Opiates are known to function as immunomodulators, in part by effects on T cells. However, the signal transduction pathways mediating the effects of opiates on T cells are largely undefined. To determine whether pathways that regulate free intracellular calcium ([Ca2+]i) and/or cAMP are affected by opiates acting through delta-type opioid receptors (DORs), a cDNA encoding the neuronal DOR was expressed in a stably transfected Jurkat T-cell line. The DOR agonists, deltorphin and [D-Ala2, D-Leu5]-enkephalin (DADLE), elevated [Ca2+]i, measured by flow cytofluorometry using the calcium-sensitive dye, Fluo-3. At concentrations from 10(-11)-10(-7) M, both agonists increased [Ca2+]i from 60 nM to peak concentrations of 400 nM in a dose-dependent manner within 30 sec (ED50 of approximately 5 x 10(-9) M). Naltrindole, a selective DOR antagonist, abolished the increase in [Ca2+]i, and pretreatment with pertussis toxin was also effective. To assess the role of extracellular calcium, cells were pretreated with EGTA, which reduced the initial deltorphin-induced elevation of [Ca2+]i by more than 50% and eliminated the second phase of calcium mobilization. Additionally, the effect of DADLE on forskolin-stimulated cAMP production was determined. DADLE reduced cAMP production by 70% (IC50 of approximately equal to 10(-11) M), and pertussis toxin inhibited the action of DADLE. Thus, the DOR expressed by a transfected Jurkat T-cell line is positively coupled to pathways leading to calcium mobilization and negatively coupled to adenylate cyclase. These studies identify two pertussis toxin-sensitive, G protein-mediated signaling pathways through which DOR agonists regulate the levels of intracellular messengers that modulate T-cell activation.
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PMID:Dual signal transduction through delta opioid receptors in a transfected human T-cell line. 871 Aug 64

Activation by opioid receptors of cell proliferation was examined with fibroblast cell lines stably expressing either delta-opioid or mu-opioid receptors. Addition of [D-Ala2, D-Leu5]-enkephalin or [D-Pen2,D-Pen5]-enkephalin to Chinese hamster ovary (CHO) cells transfected with delta-opioid receptor cDNA resulted in an agonist concentration-dependent potentiation of fetal calf serum (FCS)-stimulated cell proliferation. This potentiation by delta-opioid agonists was antagonized by naloxone and was not observed with the kappa-opioid receptor selective agonist U50,488 or the mu-opioid receptor selective agonist [D-Ala2,N-MePhe4, Gly-ol5]-enkephalin. This delta-opioid agonist effect was not observed at FCS concentrations > 0.1% and could be blocked by pretreating cells with pertussis toxin, indicating that Gi/Go were involved in this action. In addition, delta-opioid agonists could potentiate CHO cell proliferation stimulated by those growth factors that are mediated by tyrosine kinase receptors (i.e., insulin, insulin-like growth factor 1, and fibroblast-derived growth factor b). This delta-opioid agonist potentiation of growth apparently was dependent on the level of delta-opioid receptors that were expressed and had cell-line selectivity. Activation of delta-opioid receptors expressed in Rat-1 or NIH3T3 fibroblast did not result in a modulation of the cell growth induced by FCS or by growth factors. Interestingly, in CHO cells transfected with mu-opioid receptor cDNA, activation with agonists did not produce a potentiation of FCS-stimulated proliferation. This lack of mu-opioid receptor effect was not due to the differences among CHO clones. In a CHO cell line transfected with both delta-opioid receptor cDNA and mu-opioid receptor cDNA, activation of delta-but not mu-opioid receptors resulted in a potentiation of growth. These data suggest that delta- and mu-opioid receptors in CHO cells activate similar but divergent second messenger pathways, resulting in the differential regulation of cell growth.
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PMID:Agonist activation of delta-opioid receptor but not mu-opioid receptor potentiates fetal calf serum or tyrosine kinase receptor-mediated cell proliferation in a cell-line-specific manner. 901 58

Ca2+ channel modulation by the mu opioid agonist [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAGO) and the delta opiate agonists [d-Pen2, d-Pen5]-enkephalin (DPDPE) and [d-Ala2, d-Leu5]-enkephalin (DADLE) in cultured human neuroblastoma SH-SY5Y cells was investigated using the whole-cell variant of the patch-clamp technique. In SH-SY5Y cells, differentiated in vitro with retinoic acid, all agonists reversibly decreased high-voltage-activated, omega-conotoxin-sensitive Ba2+ currents in a concentration-dependent way. Inhibition was maximal with a 1 microM concentration of opiate agonists (76% with DAGO and 63% with delta agonists, when measured at 0 mV) and was characterized by a clear slow down of Ba2+ current activation at low test potentials. Both inhibition and slow down of activation were attenuated at more positive potentials, and could be partially relieved by strong conditioning depolarizations. Current suppression operated by both mu and delta agonists was prevented by pre-treatment of the cells with pertussis toxin. No sign of additivity was observed when delta agonists were applied to cells that were maximally activated by DAGO, suggesting that a common mechanism, involving the same type of modulating molecule, is responsible for Ca2+ channel inhibition promoted by activation of mu and delta opioid receptors in SH-SY5Y cells.
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PMID:Mu and delta opioid receptor activation inhibits omega-conotoxin-sensitive calcium channels in a voltage- and time-dependent mode in the human neuroblastoma cell line SH-SY5Y. 904 43

Adenylyl cyclase activity was measured following labelling of the cellular ATP pool with [3H]adenine in intact Rat-1 fibroblasts that had been stably transfected to express the murine delta-opioid receptor (clone D2). Basal [3H]cyclic AMP accumulation was low and was increased substantially by the addition of the diterpene forskolin. The synthetic enkephalin D-Ala2,D-Leu5 enkephalin (DADLE) produced strong inhibition of forskolin-amplified [3H]cyclic AMP production, whereas the delta-opioid ligand ICI174864 augmented forskolin-amplified adenylyl cyclase activity. Naloxone was unable to mimic the effects of ICI174864, and coincubation of the cells with these two ligands attenuated the effect of ICI174864. The EC50 (9.4 +/- 0.6 x 10(-8) M) for ICI174864 augmentation of forskolin-stimulated adenylyl cyclase was equal to its estimated Ki. Pertussis toxin pretreatment of clone D2 cells prevented both this effect of ICI174864 and the inhibition produced by DADLE. Use of a Cytosensor microphysiometer demonstrated that treatment of clone D2 cells with DADLE increased and that with ICI174864 decreased the basal rate of cellular proton extrusion. By using these two distinct experimental strategies, ICI174864 was shown to function in a manner anticipated for an inverse agonist, demonstrating that such effects can be observed in intact cells and are not restricted to assays performed on membrane preparations.
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PMID:Regulation of spontaneous activity of the delta-opioid receptor: studies of inverse agonism in intact cells. 934 57

A C6 glioma cell line stably transfected with the rat delta opioid receptor (C6delta) was used to characterize receptor binding and G protein activation by both peptide and nonpeptide delta opioid ligands. The ligand binding affinities for [3H]naltrindole and [3H]pCl-[D-Pen2,D-Pen5]enkephalin (DPDPE) were similar to those observed in monkey brain membranes. The nonpeptide agonists, BW373U86 and SNC80, as well as peptide agonist [D-Ser2, L-Leu5]enkephalyl-Thr maximally stimulated [35S]GTPgammaS binding by 640, 654 and 576%, respectively, over basal. The peptide agonists, DPDPE and deltorphin II, both stimulated [35S]GTPgammaS binding by 375%. Etorphine, diprenorphine, oxymorphindole and 7-spiroindanyloxymorphone were also partial agonists in this assay, although they were less efficacious than deltorphin II. Stimulation of [35S]GTPgammaS binding by agonists was blocked completely by pertussis toxin pretreatment. Both delta-1 and delta-2 selective antagonists 7-benzylidenenaltrexone and a benzofuran analog of naltrindole displayed high affinity for the cloned receptor (0.04 and 0.08 nM) and antagonized the stimulation of [35S]GTPgammaS binding by BW373U86 and DPDPE with similar potencies. Other evidence suggesting the lack of receptor subtypes includes the finding that stimulation of [35S]GTPgammaS binding by receptor subtype selective ligands DPDPE and deltorphin II was not additive. BW373U86, SNC80 and DPDPE maximally inhibited forskolin-stimulated adenylyl cyclase. These cells highly express a homogeneous population of delta opioid receptor that couple to inhibitory Go/Gi proteins. Ligand affinity for the delta opioid receptor correlates with ligand EC50 values for stimulation of [35S]GTPgammaS binding.
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PMID:Opioid efficacy in a C6 glioma cell line stably expressing the delta opioid receptor. 935 63

The ability of the delta opioid agonist DPDPE ([D-Pen2, D-Pen4]enkephalin) to stimulate binding of the GTP analog guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS) to pertussis toxin-sensitive G proteins has been characterized in membranes from NG108-15 mouse neuroblastoma X rat glioma cells. The presence of GDP, or its hydrolysis-resistant analog GDPbetaS, and Mg++ ions was essential to observe agonist-mediated stimulation of [35S]GTPgammaS binding, although the guanine dinucleotides alone had complex inhibitory and stimulatory effects on [35S]GTPgammaS binding. The relative ability of the delta antagonists benzylidenenaltrexone and naltriben to inhibit DPDPE-stimulated [35S]GTPgammaS binding suggested the opioid receptor involved was of the delta-2 subtype. Ligand binding assays demonstrated biphasic binding of these antagonists to this single receptor type. [35S]GTPgammaS binding was also stimulated by [D-Ser2,Leu5,Thr6]enkephalin > deltorphin II = DPDPE = etorphine > levallorphan = diprenorphine = nalorphine = naltrindole. The delta antagonists benzylidenenaltrexone, TIPP (Tyr-Tic-Phe-Phe) and naltriben had no effect, but ICI 174864 (N, N-diallyl-Tyr-Aib-Phe-Leu-OH) acted as an inverse agonist and inhibited [35S]GTPgammaS binding. Pertussis toxin pretreatment blocked agonist stimulation of [35S]GTPgammaS binding and also reduced basal binding, thus confirming the presence of constitutively active delta receptors. Replacement of Na+ in the assay buffer with K+ afforded an increased level of basal [35S]GTPgammaS binding and an apparent increase in both the inverse agonist activity of ICI 174864 and the agonist activity of the partial agonist diprenorphine relative to the full agonist [D-Ser2, Leu5,Thr6]enkephalin. The stimulation of [35S]GTPgammaS binding to NG108-15 cell membranes allows a functional measure of delta opioid activity that can provide systems of differing relative efficacy.
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PMID:Delta opioid modulation of the binding of guanosine-5'-O-(3-[35S]thio)triphosphate to NG108-15 cell membranes: characterization of agonist and inverse agonist effects. 940 3

In this study we employed the neuroblastoma x glioma NG 108-15 cell line as a model for investigating the effects of long-term activation of cannabinoid receptors on delta opioid receptor desensitization, down-regulation and gene expression. Exposure of NG 108-15 cells to (-)-delta9-tetrahydrocannabinol (delta9-THC) reduced opioid receptor binding, evaluated in intact cells, by approximately 40-45% in cells exposed for 24 h to 50 and 100 nM delta9-THC and by approximately 25% in cells exposed to 10 nM delta9-THC. Lower doses of delta9-THC (0.1 and 1 nM) or a shorter exposure time to the cannabinoid (6 h) were not effective. Down-regulation of 6 opioid receptors was not observed in cells exposed for 24 h to pertussis toxin (PTX) and then treated for 24 h with 100 nM delta9-THC. In cells that were exposed for 24 h to the cannabinoid, the ability of delta9-THC and of the delta opioid receptor agonist [D-Ser2, Leu5, Thr6]enkephalin to inhibit forskolin-stimulated cAMP accumulation was significantly attenuated. Prolonged exposure of NG 108-15 cells to 100 nM delta9-THC produced a significant elevation of steady-state levels of delta opioid receptor mRNA. This effect was not observed in cells pretreated with PTX. The selective cannabinoid receptor antagonist SR 141716A blocked the effects elicited by delta9-THC on delta opioid receptor desensitization, down-regulation and gene expression; thus indicating that these are mediated via activation of cannabinoid receptors. These data demonstrate the existence, in NG 108-15 cells, of a complex cross-talk between the cannabinoid and opioid receptors on prolonged exposure to delta9-THC triggered by changes in signaling through Gi and/or G0-coupled receptors.
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PMID:Regulation of delta opioid receptors by delta9-tetrahydrocannabinol in NG108-15 hybrid cells. 977 17

Opioids directly decrease the contractile response of isolated ventricular cardiomyocytes to electrical stimulation. To investigate whether these effects are mediated via GTP-binding G(i/o) proteins we examined the influence of pertussis toxin on the effects of the kappa-opioid receptor agonist trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]-benz eneacetamide (U-50,488) methanesulphonate and on the as yet undescribed effects of the opioid peptide dynorphin A (1-8) on contraction. In isolated, electrically driven, rat ventricular cardiomyocytes both agents concentration dependently reduced cell shortening within 15 min, decreasing the contractile response by 79+/-4% (n=5) and 62+/-2% (n=6) of control values at maximal effective concentrations of 10 microM (U-50,488) and 1 microM [dynorphin A (1-8)], respectively. Pertussis toxin pre-treatment (200 ng/ml; 4.5-5 h) completely abolished the effects of U-50,488 and dynorphin A (1-8) on the contractile response, indicating that these effects are mediated via G(i/o) proteins. In addition, the non-selective opioid receptor antagonist (-)-naloxone and the kappa-opioid receptor antagonist nor-binaltorphimine antagonized the effects of U-50,488 and dynorphin A (1-8) on the contractile response. Furthermore, the mu- and delta-opioid receptor agonist (D-Ala2, D-Leu5)-enkephalin (DADLE) had no effects on contraction. These results indicate that the decrease in cell shortening is due to stimulation of kappa-opioid receptors. The direct effect of kappa-opioid receptor agonists on the contractile response thus represents an additional mechanism for decreasing cardiac contractility, besides the M-cholinoceptor- or adenosine receptor-mediated pathway. It is conceivable that increased release of endogenous dynorphins from the heart during hypoxia may protect the heart in a similar manner to adenosine.
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PMID:Diminution of contractile response by kappa-opioid receptor agonists in isolated rat ventricular cardiomyocytes is mediated via a pertussis toxin-sensitive G protein. 977 24

Chronic treatment of C6 glioma cells stably expressing the rat delta opioid receptor (C6delta) with full agonists resulted in receptor down-regulation. Chronic [D-Ser2,L-Leu5]enkephalyl-Thr treatment caused a decrease in cell surface as well as a decrease in agonist-stimulated [35S]guanosine-5'-O-(3-thio)triphosphate binding. Treatment with full agonists for 12 hr resulted in a 90% decrease in receptor number that was paralleled by a decrease in the ability of agonist to stimulate [35S]guanosine-5'-O-(3-thio)triphosphate binding and inhibit forskolin-stimulated adenylyl cyclase. Of the remaining receptors, a smaller fraction of receptors (41 +/- 4 vs. 56 +/- 4% in control) exhibited high affinity for agonist as compared to receptors in control membranes. Elimination of functional guanosine triphosphate binding protein (G protein) by Pertussis toxin pretreatment did not alter the ability of agonist to down regulate receptor. We hypothesized that agonist affinity (not efficacy) would be a predictor of an agonist's ability to down-regulate receptor. However, we found that only full agonists were able to down-regulate receptor number, G protein activation and adenylyl cyclase inhibition. Chronic exposure to partial agonist 7-spiroindinooxymorphone, which has a very high affinity for the receptor, as well as morphine, did not cause receptor down-regulation. Taken together, these results suggest that full agonists alter receptor conformation such that the altered conformation is recognized by G protein as well as proteins involved in receptor down-regulation. In addition, down-regulation is independent of agonist-mediated G protein activation and subsequent down-stream signaling.
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PMID:Delta opioid receptor down-regulation is independent of functional G protein yet is dependent on agonist efficacy. 980 89


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