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)

Serotonin (5-hydroxytryptamine; 5-HT) and its analogs activate adenylate cyclase in membrane particles from neuroblastoma NCB.20 cells. Low concentrations of GTP (EC50 = 60 nM) were required for activation by serotonin. Guanosine 5'-O-(2-thiodiphosphate) inhibited serotonin-activated cyclase in these cells. The nonhydrolyzable GTP analogs guanosine 5'-O-(3-thiotriphosphate) (EC50 = 3 nM) and guanylyl-imidodiphosphate (EC50 = 100 nM) substituted for GTP in potentiating serotonin activation. Pretreatment of the cells with cholera toxin potentiated enzyme activation by serotonin, whereas pertussis toxin was found to have little effect, indicating the involvement of the alpha subunit of a stimulatory GTP-binding protein in enzyme activation. Homologous desensitization of the serotonin-stimulated adenylate cyclase was demonstrated in membranes prepared from intact cells pretreated with serotonin. Cell membrane particles that were desensitized to serotonin were still responsive to beta-adrenergic agonists and to prostaglandin E1. Evidence is presented indicating that serotonin stimulation of adenylate cyclase is mediated by receptors that are distinct from other positively coupled receptors (beta-adrenergic, histamine, and prostacyclin). Equilibrium binding analysis with [3H]serotonin, [3H]lysergic acid diethylamide, and [3H]dihydroergotamine suggested that the site density was below the level of detection of binding of these radioligands. The pharmacological characteristics of the serotonin-activated cyclases were analyzed in order to compare these serotonin receptors with the family of different receptor subtypes. Correlation analysis between the potencies of different agonists and antagonists at the cyclase in these cells and their reported relative potencies for different serotonin receptor subtypes showed no correlation with the 5-HT1A, 5HT1B, 5HT1D, 5-HT2, and 5-HT3 receptors. On the other hand, the analysis showed that the NCB.20 serotonin receptors are similar but not identical to the rat and pig brain 5-HT1C receptors and to the serotonin receptors coupled to adenylate cyclase in the trematodes Schistosoma mansoni and Fasciola hepatica. The results point to a novel serotonin receptor which has a low density in these cells.
Mol Pharmacol 1990 May
PMID:Serotonin receptor-mediated activation of adenylate cyclase in the neuroblastoma NCB.20: a novel 5-hydroxytryptamine receptor. 233 46

The role of muscarinic receptor-mediated polyphosphoinositide hydrolysis and subsequent calcium signals in altering the subcellular localization of calmodulin (CaM) was examined in SK-N-SH human neuroblastoma cells. Upon incubation of the cells with the full agonist carbachol, a 4.5- to 5-fold increase in CaM in the cytosol was observed, from 126 ng of CaM to 629 ng of CaM. There was an accompanying 68% decrease in membrane-bound CaM. The increase in the cytosol was maximal by 15 min, as was a corresponding decrease in membrane-associated CaM. The redistribution of CaM was maintained for at least 2 hr, before returning toward control levels by 4 hr. The EC50 values for carbachol in eliciting the translocation were 3.7 microM for the increase in cytosol and 1.3 microM for the decrease in membranes. The maximal changes in CaM concentration in both membranes and cytosol occurred with 10 microM carbachol. Incubation of the SK-N-SH cells with the partial muscarinic agonists bethanechol and arecoline resulted in 27 and 26% decreases in membrane-associated CaM, respectively, and 28 and 35% increases in cytosolic CaM, respectively. Thus, the partial agonists were less efficacious than carbachol in eliciting changes in CaM localization. Atropine completely blocked the carbachol-stimulated translocation, whereas the nicotinic agonist 1,1-dimethyl 4-phenylpiperazinium had no effect on the localization of CaM. Activation of receptors coupled to adenylate cyclase did not affect distribution of CaM. CaM content in membranes and cytosol of cells incubated with prostaglandin E1 or the alpha 2-adrenergic agonist UK 14,304 was not different from control values. The ionophore ionomycin (10 microM) and the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) (50 nM) were both able to elicit changes in CaM distribution. Ionomycin caused a 64% increase in CaM in the cytosol, with no significant change in membrane CaM. TPA elicited a decrease in membrane-associated CaM, with a corresponding increase in CaM in the cytosol. When TPA and ionomycin were incubated together, the translocation was equal in magnitude to that observed with carbachol alone. The protein kinase C inhibitor H-7 blocked the TPA-stimulated response and partially blocked the carbachol-stimulated response. The CaM-binding protein neuromodulin, which demonstrates a decreased affinity for CaM in the presence of Ca2+ and when phosphorylated by protein kinase C, was present in both membranes and cytosol of SK-N-SH cells.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Pharmacol 1990 Jun
PMID:Muscarinic receptor-mediated translocation of calmodulin in SK-N-SH human neuroblastoma cells. 235 3

Stimulation of soluble guanylyl cyclase in rat fetal lung fibroblasts (RFL-6 cells) was used as a sensitive assay for endothelium-derived relaxing factor/nitric oxide (EDRF/NO) formation. Intact N1E-115 cells released an EDRF/NO-like material that enhanced cyclic GMP levels in RFL-6 cells. The synthesis of this substance could be stimulated with the receptor agonist neurotensin (10 microM) or by addition of the EDRF/NO substrate L-arginine (100 microM). In Ca2(+)-free Locke's solution, stimulation of EDRF/NO production by both neurotensin and L-arginine was abolished. The EDRF/NO-synthesizing activity was localized in the cytosol of N1E-115 cells. The activity was lost after boiling and it was highly sensitive to Ca2+ with the major increase in activity occurring between 100 and 500 nM Ca2+. L-Arginine and NADPH were required for maximal synthesis of EDRF/NO by the enzyme(s). The synthesis of EDRF/NO was inhibited by the following antagonists of calmodulin-regulated functions (with the approximate IC50 values given in parentheses): calmidazolium (7 microM), trifluoperazine (10 microM), fendiline (80 microM), W-7 (N-[6-aminohexyl]-5-chloro-1-naphthalenesulfonamide) (120 microM), and compound 48/80 (3 micrograms/ml). The EDRF/NO-synthesizing activity was partially purified from N1E-115 cytosol by DE 52 anion exchange chromatography. The activity was eluted with 0.1 M KCl. The enzyme(s) showed very little activity in the presence of L-arginine (100 microM) and NADPH (100 microM), but the activity could be fully restored by addition of exogenous calmodulin (EC50, approximately 2 units/ml). At 0.3 M KCl, a fraction eluted from the DE 52 column that was also able to fully restore the EDRF/NO-synthesizing activity. Thus, this fraction is likely to contain the endogenous Ca2(+)-binding protein. It is concluded that the activity of the EDRF/NO-synthesizing enzyme(s) in N1E-115 neuroblastoma cells is regulated by Ca2+ and calmodulin.
Mol Pharmacol 1990 Jul
PMID:Hormone-induced biosynthesis of endothelium-derived relaxing factor/nitric oxide-like material in N1E-115 neuroblastoma cells requires calcium and calmodulin. 237 Aug 55

To compare the proportions of four muscarinic receptors in different rat brain regions, we used competition curves with four selective antagonists, at 1-[N-methyl-3H]scopolamine methyl chloride [( 3H]NMS) binding equilibrium and after allowing [3H]NMS dissociation for 35 min. Himbacine and methoctramine were shown to discriminate two muscarinic receptor subtypes having a high affinity for 4-diphenylacetoxy-N-methylpiperidine methiodide and hexahydrosiladifenidol, intermediate affinity for pirenzepine, and low affinity for AF-DX 116. One M4 subtype had a high affinity for himbacine and methoctramine; it was found predominantly in homogenates from rat striatum (46% of total [3H]NMS receptors) and in lower proportion in cortex (33% of [3H]NMS receptors) and hippocampus (16% of [3H]NMS receptors). Its binding properties were identical to those of muscarinic receptors in the neuroblastoma x glioma NG 108-15 hybrid, suggesting that it was encoded by m4 mRNA. The M3 subtype (typically found in rat pancreas, a tissue expressing the m3 mRNA) had a low affinity for himbacine and methoctramine and represented about 10% of all [3H]NMS receptors in rat brain cortex, hippocampus, striatum, and cerebellum. M1 and M2 receptors were identified in rat brain by their high affinity for pirenzepine and AF-DX 116, respectively.
Mol Pharmacol 1990 Aug
PMID:Binding of selective antagonists to four muscarinic receptors (M1 to M4) in rat forebrain. 238 34

Amplification of one of three growth-stimulating myc genes is a common method by which many tumor types gain a proliferative advantage. In metastatic human neuroblastoma, the amplification of the N-myc locus, located on chromosome 2, is a dominant feature of this usually fatal pediatric cancer. Of the many models proposed to explain this amplification, all incorporate as the initial step either disproportionate overreplication of the chromosomal site or recombination across a loop structure. The original locus is retained within the chromosome in the overreplication models but is excised in the recombination models. To test these models, we have used somatic cell hybrids to separate and analyze the chromosomes 2 from a neuroblastoma cell line containing in vivo amplified N-myc. Our results demonstrate that N-myc is excised from one of the chromosomes, suggesting that deletion is a requisite part of gene amplification in a naturally occurring system.
Mol Cell Biol 1990 Feb
PMID:Excision of N-myc from chromosome 2 in human neuroblastoma cells containing amplified N-myc sequences. 240 57

The role of membrane lipid composition in determining the electrical properties of neuronal cells was investigated by altering the available fatty acids in the growth medium of cultured neuroblastoma X glioma hybrid cells, clone NG108-15. Growth of the cells for several days in the presence of polyunsaturated fatty acids (linoleic, linolenic, and arachidonic) caused a pronounced decrease in the Na+ action-potential rate of rise (dV/dt) and smaller decreases in the amplitude, measured by intracellular recording. Oleic acid had no effect on the action potentials generated by the cells. In contrast, a saturated fatty acid (palmitate) and a trans monounsaturated fatty acid (elaidate) caused increases in both the rate of rise and the amplitude. No changes in the resting membrane potentials or Ca2+ action potentials of fatty acid-treated cells were observed. The membrane capacitance and time constant were not altered by exposure to arachidonate, oleate, or elaidate, whereas arachidonate caused a small increase in membrane resistance. Examination of the membrane phospholipid fatty acid composition of cells grown with various fatty acids revealed no consistent alterations which could explain these results. To examine the mechanism for arachidonate-induced decreases in dV/dt, the binding of 3H-saxitoxin (known to interact with voltage-sensitive Na+) channels was measured. Membranes from cells grown with arachidonate contained fewer saxitoxin binding sites, suggesting fewer Na+ channels in these cells. We conclude that conditions which lead to major changes in the membrane fatty acid composition have no effect on the resting membrane potential, membrane capacitance, time constant, or Ca2+ action potentials in NG108-15 cells. Membrane resistance also does not appear to be very sensitive to membrane fatty acid composition. However, changes in the availability of fatty acids and/or changes in the subsequent membrane fatty acid composition lead to altered Na+ action potentials. The primary mechanism for this alteration appears to be through changes in the number of Na+ channels in the cells.
Cell Mol Neurobiol 1985 Dec
PMID:The effects of exposure to exogenous fatty acids and membrane fatty acid modification on the electrical properties of NG108-15 cells. 241 16

Goniopora toxin (GPT), a polypeptide toxin of 9700 Da isolated from coral, markedly slows inactivation of sodium currents recorded under voltage clamp in mouse neuroblastoma cells. The voltage dependence of sodium channel activation is shifted to more negative membrane potentials by 9.8 +/- 2.1 mV, and the voltage dependence of channel inactivation is shifted to more positive membrane potential by 6.0 +/- 2.5 mV. These actions of GPT are voltage dependent with an e-fold increase in K0.5 for toxin action for each 48.3-mV depolarization between -80 and +40 mV. GPT requires Na+ or another alkali metal cation in the extracellular medium for its effect on sodium channels. The relative effectiveness of the different cations tested is Na+ greater than K+ greater than Rb+ greater than Li+ greater than Cs+ much greater than choline+. Like other polypeptide neurotoxins that slow inactivation of sodium channels, GPT enhances persistent activation of sodium channels by veratridine. However, GPT does not block the binding of 125I-labeled Leiurus scorpion toxin to neurotoxin receptor site 3 on sodium channels at concentrations which effectively slow channel inactivation. Therefore, our results define a new site on the sodium channel at which specific effects on inactivation can occur.
Mol Pharmacol 1986 Apr
PMID:Mechanism of action of a polypeptide neurotoxin from the coral Goniopora on sodium channels in mouse neuroblastoma cells. 242 33

The effects of a polypeptide toxin of 25,000 Da from the marine snail Conus striatus (CsTx) on sodium channels in mouse neuroblastoma cells and rat brain synaptosomes were studied. CsTx slowed sodium channel inactivation without altering the time course of activation of the channels. The voltage dependence of sodium channel inactivation was shifted to more negative membrane potentials and made less steep. Peak sodium currents were increased, and the voltage dependence of activation was shifted to more negative membrane potentials. The action of the toxin was voltage-dependent. Maximum toxin effects were observed at membrane potentials in the range of -100 to -60 mV. Apparent KD values were calculated assuming a one-to-one binding interaction. At more positive membrane potentials, the apparent KD for toxin action increased e-fold for each 19-mV depolarization. Apparent KD also increased at membrane potentials more negative than -100 mV. CsTx did not have significant effects on the binding of saxitoxin or Leiurus alpha-scorpion toxin to their receptor sites on sodium channels. CsTx enhanced the binding of batrachotoxinin A 20-alpha-benzoate to sodium channels in the same concentration range as its physiological effects. It is concluded that CsTx interacts with a new receptor site on the extracellular surface of the sodium channel at which specific effects on channel inactivation can occur.
Mol Pharmacol 1987 Nov
PMID:Actions of a polypeptide toxin from the marine snail Conus striatus on voltage-sensitive sodium channels. 244 15

1. Maitotoxin (MTX) was an extraordinarily potent stimulant of phosphoinositide breakdown in the neuroblastoma hybrid NCB-20 cells. 2. Maximal responses were obtained at 0.25-0.5 ng MTX/ml, and resulted in increased formation of [3H]inositol mono-, bis-, and trisphosphates. Increased formation of [3H]inositol bis- and trisphosphate was observed as early as 15 sec after the addition of MTX. 3. MTX-induced phosphoinositide breakdown in NCB-20 cells was not antagonized by organic (nifedipine, methoxyverapamil) or inorganic (Mn2+, Co2+, Cd2+) calcium channel blockers. However, the response on phosphoinositide breakdown was completely eliminated in the absence of extracellular calcium. 4. The results suggest that MTX either directly stimulates phosphoinositide breakdown in a calcium-dependent manner or acts indirectly through calcium channels insensitive to organic/inorganic calcium channel blockers.
Cell Mol Neurobiol 1987 Sep
PMID:Maitotoxin stimulates phosphoinositide breakdown in neuroblastoma hybrid NCB-20 cells. 244 66

1. The neuroblastoma x glioma hybrid NG108-15 cell line has been widely studied as a neuronal model for its serotonergic, cholinergic, and peptidergic properties. 2. The catecholamine and serotonin content and that of their major metabolites have been determined by high-performance liquid chromatography with electrochemical detection (HPLC-EC) in NG108-15 cells under differentiated and undifferentiated conditions. 3. Cellular contents of L-DOPA, norepinephrine, (NE), L-epinephrine (EPI), and dopamine (DA) in differentiated cells, induced by 1 mM dibutyryl cyclic AMP (dBcAMP), are 149, 40, 129, and 124%, respectively, higher than those in undifferentiated cells. 4. 3,4-Dihydroxyphenethylacetic acid (DOPAC), the major metabolite of DA, is detectable only in differentiated cells. Similarly, DOPAC is present only in culture medium from differentiated cells, and not that of undifferentiated cells. 5. Serotonin (5-HT) is detectable only in undifferentiated cells; and the level of 5-hydroxyindoleacetic acid (5-HIAA), the major metabolite of 5-HT, is also 12.7% higher is undifferentiated cells. 6. Comparative analyses of differentiated and undifferentiated cells in monolayer cultures and undifferentiated cells cultured in the presence of 1 mM dBcAMP under suspension conditions suggest that change in the indolamine content is due to cellular changes upon morphological differentiation. 7. The clonal NG108-15 cell line is also catecholaminergic, in addition to cholinergic and serotonergic; and a shift of neurotransmitter pattern from serotonin to dopamine production occurs during morphological differentiation.
Cell Mol Neurobiol 1989 Sep
PMID:Modification of the indolamine content in neuroblastoma x glioma hybrid NG108-15 cells upon induced differentiation. 248 34


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