Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A bioactive, fluorescent derivative of enkephalin, Tyr-D-Ala-Gly-Phe-Leu-Lys-rhodamine, was used to determine the distribution of opiate receptors in living neuroblastoma cells. The receptors appeared in clusters on the cell surface, and no internalization was detected. No specific fluorescence or clusters were observed in the presence of [D-Ala2, Leu5]enkephalin or at 4 degrees C, and the clusters were much reduced under ionic conditions (that is, with 100 millimolars sodium) that specifically decrease the binding of opiate agonists.
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PMID:Opiate (Enkephalin) receptors of neuroblastoma cells: occurrence in clusters on the cell surface. 22 58

Parameters of ligand binding, stimulation of low-Km GTPase, and inhibition of adenylate cyclase were determined in intact human neuroblastoma SH-SY5Y cells and in their isolated membranes, both suspended in identical physiological buffer medium. In cells, the mu-selective opioid agonist [3H]Tyr-D-Ala-Gly(Me)Phe-Gly-ol ([3H]DAMGO) bound to two populations of sites with KD values of 3.9 and 160 nM, with less than 10% of the sites in the high-affinity state. Both sites were also detected at 4 degrees C and were displaced by various opioids, including quaternary naltrexone. The opioid antagonist [3H]naltrexone bound to a single population of sites, and in cells treated with pertussis toxin the biphasic displacement of [3H]naltrexone by DAMGO became monophasic with only low-affinity binding present. The toxin specifically reduced high-affinity agonist binding but had no effect on the binding of [3H]naltrexone. In isolated membranes, both agonist and antagonist bound to a single population of receptor sites with affinities similar to that of the high-affinity binding component in cells. Addition of GTP to membranes reduced the Bmax for [3H]DAMGO by 87% and induced a linear ligand binding component; a low-affinity binding site, however, could not be saturated. Compared with results obtained with membranes suspended in Tris buffer, agonist binding, including both receptor density and affinity, in the physiological medium was attenuated. The results suggest that high-affinity opioid agonist binding represents the ligand-receptor-guanine nucleotide binding protein (G protein) complex present in cells at low density due to modulation by endogenous GTP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Opioid signal transduction in intact and fragmented SH-SY5Y neural cells. 156 Feb 22

Chronic treatment of neuroblastoma x glioma NG108-15 hybrid cells with the opioid agonist D-Ala,2 D-Leu5-enkephalin (DADLE) induces a homologous desensitization of the delta opioid receptors present in these cells. Since the Kd value of the delta opioid receptor's high-affinity state reflects the potency of the agonist, we examined the effect of receptor desensitization in NG108-15 cells on the percentage of receptor in the high-affinity state. When NG108-15 hybrid cells were treated with 10 or 100 nM DADLE for 4 hr at 24 degrees C, loss of DADLE's ability to inhibit adenylate cyclase was observed. However, when competition binding experiments were carried out with P2P3 membranes isolated from the delta opioid-desensitized hybrid cells, it was determined that 41.7 +/- 3.4% of the total binding sites remained in the high-affinity state, with no apparent alteration in the Kd value of either high- or low-affinity states. Similarly, when NG108-15 cells were treated with 100 ng/ml of pertussis toxin for 3 hr at 37 degrees C, 39.9 +/- 3.6% of the binding sites remained in the high-affinity state. This reduction in the percentage of receptor in high-affinity state was agonist specific, for chronic treatment of hybrid cells with levorphanol, a partial agonist, or the antagonist naloxone did not alter the percentage of opioid receptors in the high-affinity state. Furthermore, the delta opioid receptors remaining in the high-affinity state after chronic DADLE treatment were still sensitive to both Na+ and guanyldylimidodiphosphate, indicating that opioid ligand binding remained coupled to the G-proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of chronic D-Ala,2 D-Leu5-enkephalin or pertussis toxin treatment on the high-affinity state of delta opioid receptor in neuroblastoma x glioma NG108-15 hybrid cells. 184 9

Two series of dimeric enkephalin analogues were assayed for opioid activity in two isolated smooth muscle preparations: the guinea pig ileum (GPI) and the mouse vas deferens (MVD). Dimers have the general structure: X-(CH2)n-X, where X is H-Tyr-D-Ala-Gly-Phe-Leu-NH-(n = 0, 2, 4, 6, 8, 10, 12), for the first series of dimeric pentapeptide enkephalins (DPEn), and H-Tyr-D-Ala-Gly-Phe-NH-(n = 2, 4, 6, 8, 12), for the series of dimeric tetrapeptide enkephalins (DTEn). Comparison of biological activities with binding affinities revealed that: (1) the DPE series with n = 2-8 showed increased potency in the MVD assay relative to monomeric [D-Ala2, Leu5]enkephalinamide (DALEA); (2) there was an associated increase affinity for the delta receptor of rat brain or neuroblastoma-glioma hybrid cells. (however, the relative potencies were higher in the MVD assay then predicted on the basis of binding affinities); (3) the DTE series also showed an increase in delta receptor affinities and MVD potencies relative to DALEA, for n = 2-12; (4) for the DTE series, the increase in MVD activities was less than that expected on the basis of delta binding affinity; (5) for both the DPE and DTE series, activities in the GPI assay and mu-receptor affinities were highly correlated: as the length of the methylene bridge increased from 2 to 12, there was a progressive loss of activity in both assays, with a similar pattern for DPE and DTE. Two selected dimers and their corresponding monomers were also assayed for antinociceptive activity in vivo: results were consistent with GPI and mu-binding but not with MVD and delta-binding. Two alkylamide analogs of penta- and tetrapeptide monomers, representing the monomer with the attached spacer of the most active dimers, were also assayed in biological and binding assays. Comparison of these compounds with the corresponding dimers suggest that the changes in activities and selectivities induced by dimerization are not a spurious effect of the presence of an akylamide derivative of the carboxy terminal of enkephalin but rather may represent a specific effect due to the bivalent nature of the ligands.
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PMID:Receptor binding and biological activity of bivalent enkephalins. 298 28

The binding of alkylendiamide dimers of the three N-terminal residues of [D-Ala2,D-Leu5]enkephalin (DADL) to rat brain and Ng108-15 neuroblastoma-glioma cell membranes was compared with that of DADL, Tyr-D-Ala-Gly-NMe-Phe-Gly-ol (DAGO) and morphiceptin. Tritiated DADL and DAGO were used as labeled ligands for delta- and mu-receptors, respectively. Dimerization of the tripeptides resulted in dramatic increases in both mu and delta binding. The binding to mu-receptors showed two peaks at an alkyl chain length of n = 2 and approximately n = 16. In contrast, delta binding (NG108-15 cells) increased steadily with increasing chain length. The dimers with n less than 18 were mu-preferential, and the one with n = 2 showed the most dramatic increase in mu selectivity with a 400 fold higher affinity to mu- than to delta-receptors. For long-chain alkyl spacers the compounds became delta selective.
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PMID:Increased affinity and selectivity of enkephalin tripeptide (Tyr-D-Ala-Gly) dimers. 299 Sep 53

Iodinated human beta-endorphin was affinity-cross-linked to opioid receptors present in membrane preparations from bovine frontal cortex, bovine striatum, guinea pig whole brain, and rat thalamus. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography revealed covalently labeled peptides of 65, 53, 41, and 38 kilodaltons (kDa). The 65- and 38-kDa peptides were present in all four tissues. The 41-kDa peptide was seen only in bovine caudate and guinea pig whole brain while the 53-kDa peptide was absent in rat thalamus. All four labeled peptides were constituents of opioid receptors since their labeling was fully suppressed by the presence of excess opiates, such as bremazocine, during binding. The distribution and levels of the labeled species in the brain tissues examined and, in earlier work, in the neuroblastoma X glioma NG 108-15 cell line suggested that the 65-kDa peptide is a binding component of mu receptors while the 53-kDa peptide is a binding subunit of delta receptors. This result was strongly supported by the finding that the labeling of the 65-kDa peptide is selectively reduced by the presence of the highly mu-selective ligand Tyr-D-Ala-Gly-(N-Me)Phe-Gly-ol (DAMGE) during binding, while while the labeling of the 53-kDa peptide is selectively reduced or eliminated by the highly mu-selective ligand [D-Pen2, D-Pen5]enkephalin (DPDPE). The labeling of the 41- and 38-kDa bands was reduced by either DAMGE or DPDPE. The relationship of these lower molecular weight opioid-binding peptides to mu and delta receptors is not understood. Several possible explanations are presented.
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PMID:Identification of distinct binding site subunits of mu and delta opioid receptors. 300 57

A dimeric pentapeptide enkephalin (DPE2) consisting of two molecules of [D-Ala 2, Leu 5] enkephalin linked at C-terminal leucine with ethylenediamine, (H-Tyr-D-Ala-Gly-Phe-Leu-NH-Ch2)2 is a bivalent ligand for the delta enkephalin receptors of rat brain and neuroblastoma-glioma hybrid (NG108-15) cells. This new enkephalin analog shows dramatically increased affinity in radioligand assays using whole brain membranes when delta but not mu specific radioligands are employed. When membranes from NG108-15 cells are used, the dimer shows greatly increased activity irrespective of the mu or delta specificity of the tracer. The dimer DPE2 shows a four-fold, "sodium shift" in its IC50 for competition with [3H]naloxone, suggestive of agonist behavior. Agonist activity was confirmed by demonstrating that DPE2 inhibits cyclic AMP production in prostaglandin E1 stimulated NG108-15 cells, and by demonstrating very high potency in the mouse vas deferens bioassay. DPE2 binds to the same delta sites as the delta-selective monomer [D-Ala2, D-Leu5] enkephalin, since the two ligands show complete crossdisplacement. Radiolabeled 3H-DPE2 shows a five-fold higher affinity constant, a 2.5-fold higher association rate constant, and a two-fold lower dissociation rate than the monomer. These results are consistent with the hypothesis that the dimeric pentapeptide enkephalin can bridge two delta receptors. This enkephalin dimer provides a valuable new probe of opiate receptors and their organization in cell membranes.
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PMID:Dimeric pentapeptide enkephalin: a novel probe of delta opiate receptors. 629 43

This study reports on the molecular mechanism of delta-opiate receptor down regulation on 108CC15 neuroblastoma X glioma hybrid cells. The down regulation induced by culture in the presence of 10(-5) M 2-D-Ala, 5-D-Leu-enkephalin (DADLE) can be prevented by continued exposure to ligand concentrations greater than 4 nM, the Kd of the binding site. Below this concentration, down regulation is a rapid and irreversible process. It is deduced that the internalization process in this cell line is initiated when unoccupied receptor dimers are present. These results have important implications for down regulation studies using cultured cell lines and studies of receptor regulation in vivo after chronic treatment with neuroactive drugs.
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PMID:Down regulation of opiate receptors on 108CC15 hybrid cells is inhibited by receptor occupancy. 632 48

Neuroblastoma x glioma hybrid, NG108-15, cells appear to express the alpha-subunit of the guanine nucleotide-binding protein Gs in a substantial molar excess over its effector adenylate cyclase [Kim, Adie and Milligan (1994) Eur. J. Biochem. 219, 135-143]. Addition of the IP prostanoid receptor agonist iloprost to intact NG108-15 cells resulted in a dose-dependent increase in formation of the complex between Gs alpha and adenylate cyclase (GSAC) as measured by specific high-affinity binding of [3H]forskolin. NG108-15 cells transfected to express either relatively high (clone beta N22) or low (clone beta N17) levels of beta 2-adrenoceptor both showed dose-dependent increases in specific [3H]forskolin binding in response to the beta-adrenoceptor agonist isoprenaline, and maximally effective concentrations of isoprenaline resulted in the generation of similar numbers of GSAC complexes in both clones. The dose-effect curve for clone beta N22, however, was some 15-fold to the left of that for clone beta N17, which is similar to that noted for isoprenaline-mediated stimulation of adenylate cyclase activity [Adie and Milligan (1994) Biochem. J. 303, 803-808]. In contrast, dose-effect curves for iloprost stimulation of [3H]forskolin binding were not different in clones beta N22 and beta N17. Basal specific [3H]forskolin binding in the absence of agonist was significantly greater in cells of clone beta N22 than clone beta N17. This was not a reflection of higher immunological levels of adenylate cyclase, indicating that the higher basal formation of GSAC probably reflects empty-receptor activation of Gs. This higher basal specific [3H]forskolin binding was partially reversed by propranolol. The addition of the opioid peptide D-Ala-D-Leu-enkephalin to NG108-15 cells did not reduce iloprost-stimulated [3H]forskolin binding even though this peptide inhibits stimulated adenylate cyclase activity by activation of a delta opioid receptor.
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PMID:Detection and analysis of agonist-induced formation of the complex of the stimulatory guanine nucleotide-binding protein with adenylate cyclase in intact wild-type and beta 2-adrenoceptor-expressing NG108-15 cells. 753 56

The human neuroblastoma cell line SH-SY5Y was used to demonstrate morphine-induced down-regulation and naloxone-induced up-regulation of opiate receptors in a mu receptor containing neuronally derived preparation capable of desensitization to morphine. Chronic exposure to morphine decreased the number but not the affinity of mu opiate receptors in SH-SY5Y cells. Differentiation of the cells with retinoic acid or with the phorbol agent TPA (12-O-tetradecanoyl-phorbol-13-acetate) increased the number of mu receptors. Morphine-induced down-regulation, however, was observed in the absence of differentiation as well as after differentiation with retinoic acid or TPA. The decrease in the number of receptors was related to time of exposure, with a half-maximum disappearance time (T1/2) of about 3 hr during the initial phase. The receptor decrease was near maximum at 24 hr with no further significant change up to 72 hr. The loss of [3H] DAMGO ([3H]Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol) binding was also dose-dependent, with reductions occurring at 0.3, 1 and 10 microM. The loss of receptors was dependent on temperature, with reductions at 37 but not 23 degrees C. The down-regulation was blocked by naloxone and the mu-selective antagonist CTOP (D-Phe-Cys-Tyr-D(-Trp-)Orn-Thr-Pen-Thr-NH2), but not by the delta antagonist ICI 174864 ([N,N-diallyl-Tyr1,Aib2,3]Leu-enkephalin). Cholinergic ([3H]quinclidinyl benzilate) binding was not affected by the morphine treatment, indicating that the down-regulation was homologous for opiate receptors. In SH-SY5Y cells, unlike other cell models, the opiate antagonist naloxone upregulated mu receptors by more than 50%.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mu opiate receptor down-regulation by morphine and up-regulation by naloxone in SH-SY5Y human neuroblastoma cells. 809 44


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