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)

The guanine nucleotides GDP, GTP, and guanosine-5'-(beta, gamma-imido)triphosphate inhibit binding of opiates and opioid peptides to receptors solubilized from membranes of neuroblastoma X glioma NG108-15 hybrid cells. The inhibition reflects decreased affinity of receptors for opioid ligands. Whereas in membranes, only opioid agonist binding is sensitive to guanine nucleotide inhibition, both agonist and antagonist binding is reduced in the case of soluble receptors. Furthermore, soluble receptors are more sensitive to the effects of guanine nucleotides than are membrane-bound receptors. These observations are consistent with the suggestion that solubilized receptors may be complexes of an opiate binding protein and a guanine nucleotide-sensitive regulatory component.
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PMID:Guanine nucleotides inhibit binding of agonists and antagonists to soluble opiate receptors. 625 76

D-Ala2-Met5-enkephalin, morphine, and noradrenaline inhibit the adenylate cyclase in homogenates of neuroblastoma x glioma hybrid cells in a dose-dependent manner even after the enzyme has been preactivated by cholera toxin. Half-maximal inhibition and extent of inhibition are the same with native or cholera toxin-activated enzyme. The inhibition caused by opioids or noradrenaline are antagonized by naloxone or phentolamine, respectively. The effect of D-Ala2-Met5-enkephalin on cholera toxin-activated enzyme is immediate in onset and rapidly reversed by the addition of naloxone. Guanyl-5'-yl-imidodiphosphate stimulates basal activity but inhibits the enzyme activated by cholera toxin or prostaglandin E1. Stimulation occurs at a concentration of 100 microM or above, inhibition even at 0.1 microM. The inhibitory effect of the non-hydrolysable GTP analog is antagonized by GTP. Guanyl-5'-yl-methylenediphosphonate, another nonhydrolysable GTP analog, inhibits basal as well as cholera toxin-stimulated or prostaglandin E1-stimulated adenylate cyclase. Other guanine derivatives such as GDP, GMP, cyclic GMP, guanyl-5'-yl-phosphoric acid amide and guanosine have no effect under the same conditions. The results may be taken as a piece of evidence for two separate guanyl nucleotide-binding sites accompanying the adenylate cyclase in the hybrid cells and mediating, respectively, stimulation and inhibition of the enzyme by hormones.
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PMID:Opioids, noradrenaline and GTP analogs inhibit cholera toxin activated adenylate cyclase in neuroblastoma x glioma hybrid cells. 625 56

It has been repeatedly demonstrated that the neuroblastoma-glioma (NG 108-15) cell line has opiate receptors that inhibit adenylate cyclase and it has been proposed that this inhibition is mediated by a naloxone reversible stimulation of a low Km GTPase (Koski and Klee, Proc. Natl. Acad. Sci. 78:4185, 1981). The guanine nucleotides of NG cells were labeled with [3H]guanine followed by incubation with 10(-6)M guanine. Etorphine (10(-6)M) or vehicle were added and the incubations continued for 1-4 min. The reaction was stopped with 5 percent TCA containing nucleotides as carriers and markers for the HPLC. Marker nucleotides were detected at 254 nm and the labeled nucleotides by liquid scintillation spectrometry. In several experiments, etorphine failed to produce any measurable change in the labeled nucleotides or in the GTP/GDP ratios. To verify that the opiate receptors were functional we measured its capacity to inhibit the formation of cAMP induced by PGE1. We also studied the effects of naloxone and PGE1 on the formation of cAMP in opiate tolerant cells. Tolerant cells responded to naloxone with a 50 percent increase in cAMP, indicating again that the opiate receptors were functional. Our results are consistent with the idea that in intact NG108-15 cells the opiate-mediated hydrolysis of GTP observed in cell membrane preparations is of very small magnitude.
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PMID:Failure of opiates to increase the hydrolysis of GTP in neuroblastoma-glioma 108-15 cells. 631 Mar 3

We have proposed recently that a pertussistoxin-insensitive Ca2+ influx stimulated by Y2-type receptor activation in CHP-234 human neuroblastoma cells underlies increases in intracellular free Ca2+ concentration ([Ca2+]i) induced by neuropeptide Y (NPY), which were strictly dependent on extracellular Ca2+ and independent of internal Ca2+ stores. We describe here the actions of NPY in these same cells, using the activity of Ca(2+)-activated K+ channels as an indicator of [Ca2+]i. The elementary slope conductance of these channels was 110 +/- 3 pS (with an asymmetrical K+ gradient), their activity was greatly increased by application of ionomycin, and they were reversibly blocked by 1 mM tetraethylammonium (TEA) and 100 nM charybdotoxin. Application of 100 nM NPY, in the presence but not in the absence of extracellular Ca2+, increased the channel open probability. ATP applied in the absence of external Ca2+ caused rises both in channel open probability and [Ca2+]i. Inositol trisphosphate production was stimulated by ATP but not by NPY. In outside-out patches, NPY increased channel open probability, indicating that NPY-associated Ca2+ influx does not require all the intracellular machinery present in intact cells. Channel activation by NPY was unaffected by the replacement of guanosine 5'-triphosphate (GTP) by (guanosine 5'-O-(2-thiodiphosphate) (GDP[ beta S]), a non-hydrolysable GDP analogue, in the pipette internal solution, consistent with the lack of involvement of G-proteins in the coupling of Y2-type receptors to Ca2+ influx in CHP-234 cells.
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PMID:Neuropeptide Y2-type receptor-mediated activation of large-conductance Ca(2+)-sensitive K+ channels in a human neuroblastoma cell line. 749 Dec 80

Rab proteins, a family of Ras-related small GTP-binding proteins, play a key role in regulating intracellular vesicle trafficking. Rab GDP dissociation inhibitor (GDI3) forms a soluble complex with Rab proteins and thereby prevents the exchange of GDP for GTP. Recently, two isoforms of Rab GDI cDNA were isolated from rats and mice. In this study, we have isolated a brain-type isoform of human Rab GDI cDNA and examined its expression in neuroblastoma. We tentatively designate it as human Rab GDI alpha (hu GDI alpha) and another human Rab GDI, as human Rab GDI beta (hu GDI beta). Hu GDI alpha cDNA encodes a protein of 447 amino acids with a deduced molecular weight of 50,200. Northern blot analysis revealed that hu GDI alpha gene is expressed abundantly in the brain but much less in other tissues, while hu GDI beta gene is ubiquitously expressed. All human neuroblastoma cell lines and tumor specimens examined express hu GDI alpha gene to various extents, while a human T cell leukemia cell line, MOLT3, does not. The levels of both hu GDI alpha and beta mRNA were constant in a human neuroblastoma cell line, NB1, during its neuronal differentiation, while Rab3A and neurofilament-L gene expression and the number of neurosecretory granules were elevated at this condition. These results suggest that hu GDI alpha gene expression is not related to the differentiation state of neuronal cells.
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PMID:Cloning of a brain-type isoform of human Rab GDI and its expression in human neuroblastoma cell lines and tumor specimens. 758 14

The ability of mu-opioid agonists to activate G proteins has been demonstrated by studying the binding of the GTP analogue guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTP gamma S) to membranes from the human neuroblastoma SH-SY5Y cell line. The potent opioid agonist fentanyl caused an approximate doubling of basal [35S]GTP gamma S binding in a naloxone-sensitive manner, confirming this to be an opioid receptor-mediated process. The presence of GDP was necessary to observe this effect. Pretreatment of the cells with pertussis toxin (100 ng/ml, for 24 hr) completely prevented the fentanyl-stimulated increase in [35S]GTP gamma S binding and lowered the basal binding of [35S]GTP gamma S. These latter data suggest an involvement of Gi and/or Go proteins and their activation by added membrane-bound receptors even in the absence of agonist. The order of potency of a series of opioid agonists in stimulating the binding of [35S]GTP gamma S was buprenorphine > cyclazocine = levallorphan > nalorphine > [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO) > fentanyl > morphine > pentazocine. DAMGO, fentanyl, and morphine were full agonists but the remaining compounds showed decreasing levels of intrinsic activity in the order buprenorphine > pentazocine > cyclazocine = nalorphine > levallorphan. The opioid antagonist naloxone was without effect. Under the conditions of the [35S]GTP gamma S assay, binding of agonists was to a high affinity site, indicating that a high agonist affinity state of the mu-opioid receptor is responsible for the observed stimulation of [35S]GTP gamma S binding. The level of [35S]GTP gamma S binding (597 fmol/mg of protein) stimulated by DAMGO was 2-fold greater than the maximal number of mu-opioid agonist binding sites (Bmax) determined using [3H]DAMGO (254 fmol/mg of protein). The opioid agonist-mediated stimulation of [35S]GTP gamma S binding in SH-SY5Y cell membranes thus provides a "functional" measure of agonist occupation of mu-opioid receptors and offers a simple method for the determination of efficacy and intrinsic activity of mu-opioid agonists.
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PMID:Modulation by mu-opioid agonists of guanosine-5'-O-(3-[35S]thio)triphosphate binding to membranes from human neuroblastoma SH-SY5Y cells. 772 47

p21ras is a membrane-associated guanine nucleotide-binding protein with intrinsic GTPase activity. Like other guanine nucleotide-binding proteins p21ras is active when GTP bound and inactive when GDP bound. Phosphorylation of p21ras is regulated by the GTPase activity of type I GAP120 and NF1-GRD. In this study we have identified type I GAP120 and two NF1-GRD mRNAs in three neuroblastoma cell lines, IMR-32, SK-N-SH and SK-N-MC. NF1-GRD mRNA was expressed in all cell lines at a similar level but type I GAP120 mRNA was more abundant in the IMR-32 cell line. Retinoic acid induced differentiation of all three cell lines, this effect was most marked in the SK-N-SH line. This differentiation was accompanied by an increase in both type I GAP120 and NF1-GRD mRNAs. Retinoic acid induced differentiation had no effect on the ratio of type I to type II NF1-GRD mRNA. In seven patient tumour samples examined type I GAP120 and NF1-GRD were coexpressed, type I GAP120 at a higher level than NF1-GRD in all tumour stages. Type I was the predominant NF1-GRD mRNA. The expression of type I GAP120 was similar in all tumour stages but the total level of NF1-GRD was higher in stage 2 and 3 tumours than in stage 4 tumours. In summary, these results suggest increased type I GAP120 and NF1-GRD mRNA are associated with differentiation in neuroblastoma cells.
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PMID:Changing expression of GTPase activating proteins with differentiation in neuroblastoma. 785 16

1. Acetylcholine (ACh) produces two membrane current changes when applied to NG108-15 mouse neuroblastoma x rat glioma hybrid cells transformed (by DNA transfection) to express m1 muscarinic receptors: it activates a Ca(2+)-dependent K+ conductance, producing an outward current, and it inhibits a voltage-dependent K+ conductance (the M conductance), thus diminishing the M-type voltage-dependent K+ current (IK(M)) and producing an inward current. The present experiments were undertaken to find out how far inhibition of IK(M) might be secondary to stimulation of phospholipase C, by recording membrane currents and intracellular Ca2+ changes with indo-1 using whole-cell patch-clamp methods. 2. Bath application of 100 microM ACh reversibly inhibited IK(M) by 47.3 +/- 3.2% (n = 23). Following pressure-application of 1 mM ACh, the mean latency to inhibition was 420 ms at 35 degrees C and 1.79 s at 23 degrees C. Latencies to inhibition by Ba2+ ions were 148 ms at 35 degrees C and 92 ms at 23 degrees C. 3. The involvement of a G-protein was tested by adding 0.5 mM GTP-gamma-S or 10 mM potassium fluoride to the pipette solution. These slowly reduced IK(M), with half-times of about 30 and 20 min respectively, and rendered the effect of superimposed ACh irreversible. Effects of ACh were not significantly changed after pretreatment for 24 h with 500 ng ml-1 pertussis toxin or on adding up to 10 mM GDP-beta-S to the pipette solution. 4. The role of phospholipase C and its products was tested using neomycin (to inhibit phospholipase C), inositol 1,4,5-trisphosphate (InsP3) and inositol 1,3,4,5-tetrakisphosphate (InsP4), heparin, and phorbol dibutyrate (PDBu) and staurosporin (to activate and inhibit protein kinase C respectively). Both neomycin (1 mM external) and InsP3 (100 microM intrapipette) inhibited the ACh-induced outward current and/or intracellular Ca2+ transient but did not block ACh-induced inhibition of IK(M). Intrapipette heparin (1 mM) blocked activation of IK(Ca) and reduced Ach-induced inhibitions of IK(M), but also reduced inhibition of ICa via endogeneous m4 receptors. PDBu (with or without intrapipette ATP) and staurosporin had no significant effects.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:On the mechanism of M-current inhibition by muscarinic m1 receptors in DNA-transfected rodent neuroblastoma x glioma cells. 827 Nov 96

To examine the possibility that NaF enhances phosphoinositide-specific phospholipase C (PIC) activity in neural tissues by a mechanism independent of a guanine nucleotide binding protein (Gp), we have evaluated the contribution of Gp activation to NaF-stimulated phosphoinositide hydrolysis in human SK-N-SH neuroblastoma cells. Addition of NaF to intact cells resulted in an increase in the release of inositol phosphates (450% of control values; EC50 of approximately 8 mM). Inclusion of U-73122, an aminosteroid inhibitor of guanine nucleotide-regulated PIC activity in these cells, resulted in a dose-dependent inhibition of NaF-stimulated inositol lipid hydrolysis (IC50 of approximately 3.5 microM). When added to digitonin-permeabilized cells, NaF or guanosine-5'-O-thiotriphosphate (GTP gamma S) resulted in a three- and sevenfold enhancement, respectively, of inositol phosphate release. In the combined presence of optimal concentrations of NaF and GTP gamma S, inositol phosphate release was less than additive, indicative of a common site of action. Inclusion of 2-5 mM concentrations of guanosine-5'-O-(2-thiodiphosphate) (GDP beta S) fully blocked phosphoinositide hydrolysis elicited by GTP gamma S, whereas that induced by NaF was partially inhibited (65%). However, preincubation of the cells with GDP beta S resulted in a greater reduction in the ability of NaF to stimulate inositol phosphate release (87% inhibition). Both GTP gamma S and NaF-stimulated inositol phosphate release were inhibited by inclusion of 10 microM U-73122 (54-71%). The presence of either NaF or GTP gamma S also resulted in a marked lowering of the Ca2+ requirement for activation of PIC in permeabilized cells. These results indicate that in SK-N-SH cells, little evidence exists for direct stimulation of PIC by NaF and that the majority of inositol phosphate release that occurs in the presence of NaF can be attributed to activation of Gp.
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PMID:Contribution of G protein activation to fluoride stimulation of phosphoinositide hydrolysis in human neuroblastoma cells. 838 24

Mouse neuroblastoma x rat glioma hybrid cells (N x G, NG108-15) were used to study the mechanism of Ca(2+)-current (ICa) inhibition by 5-hydroxytryptamine (5-HT). 5-HT caused a dose-dependent decrease of ICa which was abolished by ICS 205-930 (10)(-8) M) while 2-methyl-5-HT was an agonist. Intracellular infusion of GDP beta S (50 microM) prevented the 5-HT-induced inhibition of ICa whereas pertussis toxin (PTX) pretreatment did not alter the 5-HT response. The 5-HT-induced inhibition depended on the free Ca(2+)-concentration in the pipette solution. Pretreating N x G cells with low molecular weight (LMW) heparin (160 micrograms/ml), 200 microM ryanodine or 2-10 mM caffeine attenuated the 5-HT-induced inhibition of ICa. From these results we suggest that the 5-HT-induced ICa inhibition requires release of Ca2+ from intracellular stores.
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PMID:Role of intracellular Ca(2+)-stores in the 5-hydroxytryptamine-induced Ca(2+)-current inhibition in NG108-15 hybrid cells. 839 30


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