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 presence of small G proteins was investigated by [gamma-35S]GTP-binding in 3 human neuroblastoma cell lines. IMR-32, SK-N-BE and SH-SY5Y, before and after treatment with differentiating agents (dibutyryl-cAMP, 5-bromodeoxyuridine or retinoic acid) which induce the appearance of secretory organelles. One major component of about 24 kDa and 3 minor components of smaller Mr were found to bind specifically [gamma-35S]GTP in all 3 cell lines already before differentiation. Differentiation did not affect the expression of small G proteins in IMR-32 cells and only modestly affected it in the other two cell lines. The possibility that the expression of small G proteins in neuroblastoma cells is not coupled with the assembly of secretory organelles is discussed.
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PMID:Small GTP-binding proteins in human neuroblastoma cell lines. 190 63

A 360 residue region encoded by the neurofibromatosis type 1 (NF1) gene shows significant homology to the catalytic domains of both mammalian GTPase-activating proteins (GAP) and yeast IRA proteins. This GAP-related domain of the NF1 gene (NF1-GRD), like the GAP and IRA protein, has been reported to mediate hydrolysis of Ras-bound GTP to GDP, resulting in inactivation of Ras protein. In the present study, we identified two different types of NF1-GRD cDNA. One (type I) is identical to the previously reported sequence, and the other (type II) contained an additional 63 bp insertion that encodes for a region of 21 amino acids in the center of the NF1-GRD molecule. Alternative splicing is the most likely mechanism by which these two types of transcripts arise. Our observations reveal that the type I transcript is predominantly expressed in undifferentiated cells, whereas the type II transcript predominates in differentiated cells. Furthermore, the expression pattern of type I and type II NF1-GRD mRNA immediately changed in SH-SY5Y neuroblastoma cells when neuronal differentiation programs were induced by retinoic acid treatment. We propose that the differential expression of type I and type II NF1-GRD transcripts might be an 'on/off' switch that regulates the catalytic activity of the NF1 gene product, which plays an important role in the regulation of neuronal differentiation.
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PMID:Differential expression of two types of the neurofibromatosis type 1 (NF1) gene transcripts related to neuronal differentiation. 192 22

The regulation of GTP-binding proteins (G proteins) was examined during the course of differentiation of neuroblastoma N1E-115 cells. N1E-115 cell membranes possess three Bordetella pertussis toxin (PTX) substrates assigned to alpha-subunits (G alpha) of Go (a G protein of unknown function) and "Gi (a G protein inhibitory to adenylate cyclase)-like" proteins and one substrate of Vibrio cholerae toxin corresponding to an alpha-subunit of Gs (a G protein stimulatory to adenylate cyclase). In undifferentiated cells, only one form of Go alpha was found, having a pI of 5.8 Go alpha content increased by approximately twofold from the undifferentiated state to 96 h of cell differentiation. This is mainly due to the appearance of another Go alpha form having a pI of 5.55. Both Go alpha isoforms have similar sizes on sodium dodecyl sulfate-polyacrylamide gels, are recognized by polyclonal antibodies to bovine brain Go alpha, are ADP-ribosylated by PTX, and are covalently myristylated in whole N1E-115 cells. In addition, immunofluorescent staining of N1E-115 cells with Go alpha antibodies revealed that association of Go alpha with the plasma membrane appears to coincide with the expression of the most acidic isoform and morphological cell differentiation. In contrast, the levels of both Gi alpha and Gs alpha did not significantly change, whereas that of the common beta-subunit increased by approximately 30% over the same period. These results demonstrate specific regulation of the expression of Go alpha during neuronal differentiation.
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PMID:Neuroblastoma differentiation involves the expression of two isoforms of the alpha-subunit of Go. 210 77

Vasoactive intestinal contractor (VIC) caused a series of biochemical events, including the temporal biphasic accumulation of 1,2-diacylglycerol (DAG), transient formation of Ins(1,4,5)P3, and increase in intracellular free Ca2+ [( Ca2+]i) in neuroblastoma NG108-15 cells. In these cellular responses, VIC was found to be much more potent in NG108-15 cells than in cultured rat vascular smooth-muscle cells. The single cell [Ca2+]i assay revealed that in the presence of nifedipine (1 microM) or EGTA (1 mM), the peak [Ca2+]i declined more rapidly to the resting level in VIC-stimulated NG108-15 cells, indicating that the receptor-mediated intracellular Ca2+ mobilization is followed by Ca2+ influx through the nifedipine-sensitive Ca2+ channel. Pretreatment with pertussis toxin only partially decreased Ins(1,4,5)P3 generation as well as the [Ca2+]i transient induced by VIC, whereas these events induced by endothelin-1 were not affected by the toxin, suggesting involvement of distinct GTP-binding proteins. The VIC-induced transient Ins(1,4,5)P3 formation coincident with the first early peak of DAG formation suggested that PtdIns(4,5)P2 is a principal source of the first DAG increase. Labelling studies with [3H]myristate, [14C]palmitate and [3H]choline indicated that in neuroblastoma cells phosphatidylcholine (PtdCho) was hydrolysed by a phospholipase C to cause the second sustained DAG increase. Down-regulation of protein kinase C (PKC) by prolonged pretreatment with phorbol ester markedly prevented the VIC-induced delayed DAG accumulation. Furthermore, chelation of intracellular CA2+ completely abolished the second sustained phase of DAG production. These findings suggest that PtdCho hydrolysis is responsible for the sustained production of DAG and is dependent on both Ca2+ and PKC.
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PMID:Receptor-linked early events induced by vasoactive intestinal contractor (VIC) on neuroblastoma and vascular smooth-muscle cells. 212 5

Chronic opioid treatment of neuroblastoma x glioma NG108-15 cells induces desensitization of the opioid receptor and this may involve a change in membrane protein phosphorylation. In an attempt to mimic this possible mechanism, we studied effects of phorbol ester activation of protein kinase C on opioid receptor activity. Incubation of NG108-15 hybrid cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) abolished up to 45% of opioid inhibition of cyclic AMP accumulation in intact cells, while basal accumulation and prostaglandin E1-stimulated cyclic AMP accumulation were unaltered. This decrease of opioid inhibition was dose- and time-dependent and the potency order of phorbol esters and apparent K activation (90 nM) for TPA were consistent with phorbol esters acting through the stimulation of protein kinase C. TPA also decreased the inhibition of cyclic AMP accumulation mediated through muscarinic and alpha-2 adrenergic receptors. These effects of TPA were best explained by a TPA-induced alteration of the inhibitory nucleotide-binding protein (Gi), the common transducer protein of these receptors. Impairment of Gi by TPA treatment was evidenced by a reduction in agonist-stimulated GTP hydrolysis and activation by GTP. Quantification of Gi by pertussis toxin-catalyzed ADP-ribosylation revealed that TPA decreased maximal labeling. In summary, phorbol esters appeared to attenuate opioid receptor activity by altering the activity of the transducer protein Gi.
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PMID:Attenuation of opioid receptor activity by phorbol esters in neuroblastoma x glioma NG108-15 hybrid cells. 215 50

Treatment of NG108-15 neuroblastoma x glioma cells (24 h) with cholera toxin (0.1-10 micrograms/ml) resulted in a concentration-dependent reduction of the membrane levels of subunits of GTP-binding regulatory proteins (G proteins), as determined by quantitative immunoblot procedures. The extent of reduction differed for different types of subunits: the levels of Go alpha and G beta 1 were reduced by 40-50%, whereas those of G alpha common immunoreactivity and Gi2 alpha were only reduced by 10-20% following treatment with 10 micrograms/ml cholera toxin. This effect of the toxin could not be mimicked by incubation with the resolved B oligomer of cholera toxin, nor by exposure of cells to agents able to raise the intracellular levels of cAMP. Basal adenylate cyclase was stimulated in a biphasic manner by cholera toxin, being stimulated at low concentrations (0.01-10 ng/ml) and then decreased at high (0.1-10 micrograms/ml) concentrations. Thus, the down regulation of G-protein subunits produced by cholera toxin requires its (ADP-ribosyl)transferase activity but does not result from a cAMP-mediated mechanism. The toxin-mediated decrease of Go alpha in the membrane was correlated with a diminution of opioid-receptor-mediated stimulation of high-affinity GTPase activity, suggesting that opioid receptors interact with Go in native membranes of NG108-15 cells. Northern-blot analysis of cytoplasmic RNA prepared from cells treated with cholera toxin showed that the levels of mRNA coding for G beta 1 did not change. Thus, the cholera-toxin-induced decrease of G-protein subunits may not result from an alteration in mRNA levels, but may involve a direct effect of the toxin on the process of insertion and/or clearance of G proteins into and/or from the membrane. These data indicate that cholera toxin, besides catalyzing the ADP-ribosylation of Gs and Gi/Go types of G proteins, can also reduce the steady state levels of Go alpha and G beta 1 subunits in the membrane and thus alter by an additional mechanism the function of inhibitory receptor systems.
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PMID:Cholera toxin differentially decreases membrane levels of alpha and beta subunits of G proteins in NG108-15 cells. 215 84

In the neuroblastoma X glioma hybrid cell line NG108-15, bradykinin (BK) receptor stimulation induced a rapid and concentration-dependent rise in cytosolic free Ca2+ levels, as measured with the Ca2(+)-sensitive fluorescent dye fura-2. The Ca2+ transient was present in the absence of extracellular Ca2+ and was associated with a concentration-dependent production of inositol phosphates, particularly inositol trisphosphate (InsP3). Pretreatment of intact NG108-15 cells with forskolin or dibutyryl-cAMP plus isobutylmethylxanthine reduced BK-stimulated InsP3 production and the increase in cytosolic free Ca2+. Membranes prepared from forskolin- and [3H]inositol-pretreated NG108-15 cells also showed a diminished production of InsP3 elicited by guanosine 5'-[gamma-thio]triphosphate, NaF, or BK plus GTP. On the other hand, the Ca2+ sensitivity of membrane-associated phosphoinositide-specific phospholipase C (PI-PLC) was unaffected by forskolin pretreatment of intact NG108-15 cells. Collectively, these results suggest that A-kinase may inhibit receptor-mediated and postreceptor stimulation of PI-PLC in neuron-like cells, perhaps by impairing the coupling between a guanine nucleotide-binding protein and PI-PLC.
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PMID:Cyclic AMP inhibits inositol polyphosphate production and calcium mobilization in neuroblastoma X glioma NG108-15 cells. 216 7

The effect of triiodothyronine (T3) on the differentiation of cultured neuroblastoma (NB) cells was studied after 9 days of treatment with a dose of 10(-4) M/10(6) cells per day. Using phase contrast microscopy, 30-50% of NB cells showed formation of neurites as a morphological sign of cellular differentiation. The initial rise of the mitosis rate was followed by a plateau. Changes in cyclic nucleotide content, in the triphosphates and in the activity of the enzyme ornithine decarboxylase (ODC) were assessed in 2 human and 2 murine cell lines to serve as biochemical parameters of the cell differentiation induced by T3. Whereas the cAMP level increased significantly (3 to 7 fold compared with its initial value), the cGMP value dropped to 30 to 50% of that of the control group. ATP and GTP increased about 200%, the ODC showed a decrease of about 50%. The present studies show a biphasic effect of T3 on neuroblastoma cells: the initial rise of mitotic activity is followed by increased cell differentiation starting from day 4 of the treatment.
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PMID:[In vitro and in vivo effect of thyroid hormones on the growth of neuroblastoma cells. I. The effect of triiodothyronine in vitro]. 216 39

In membranes of undifferentiated neuroblastoma x glioma hybrid cell line NG108-15, the apparent specific binding of [3H]yohimbine measured in the presence of 1 microM noradrenaline, was increased substantially by the presence of the poorly hydrolysed analogue of GTP, guanylyl-imidodiphosphate (Gpp[NH]p) or by preincubation of membranes with antibodies against the C-terminal decapeptide of the alpha subunit of the G-protein Gi2. Such an effect was not produced by antibodies against the equivalent region of Go alpha Gi3 alpha or Gs alpha or from non-immune serum. By contrast, total specific binding of [3H]yohimbine was not modified by co-incubation with Gpp[NH]p or by preincubation with the antibodies from any of the anti-G protein antisera. These results demonstrate a direct interaction of the alpha 2B adrenergic receptor of NG108-15 cells with Gi2.
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PMID:The alpha 2B adrenergic receptor of undifferentiated neuroblastoma x glioma hybrid NG108-15 cells, interacts directly with the guanine nucleotide binding protein, Gi2. 216 34

On account of the postulated existence of 5-HT3 receptor subtypes, the respective physico-chemical and pharmacological properties of specific binding sites for the potent 5-HT3 antagonist [3H]zacopride were compared using membranes from the rat posterior cortex or neuroblastoma-glioma NG 108-15 clonal cells. In both membrane preparations, [3H]zacopride bound to a single class of specific sites with a Kd close to 0.5 nM. However, the Bmax value in NG 108-15 cell membranes (970 +/- 194 fmol/mg protein) was approximately 50 times larger than that in cortical membranes (19 +/- 2 fmol/mg protein). The specific binding of [3H]zacopride was equally affected by temperature, pH and molarity of the assay medium, and equally insensitive to thiol- and disulfide-reagents (N-ethylmaleimide, p-chloromercuribenzene sulfonic acid, dithiothreitol) and GTP in cortical as well as NG 108-15 cell membranes. Determination of the molecular size of [3H]zacopride specific binding sites by radiation inactivation yielded values close to 35 kDa for both membrane preparations. Finally, a highly significant positive correlation (r = 0.979) was found between the respective pKi values of 34 different drugs for their inhibition of [3H]zacopride specific binding to cortical or NG 108-15 cell membranes. Among them, the most potent was S(-)zacopride (pKi = 9.55), followed by BRL 43964, ICS 205-930, quipazine, R(+)zacopride, GR 38032F and MDL 72222. Atypical antidepressants (mianserin, amoxapine) and neuroleptics (clotiapine, loxapine and clozapine) were active in rather low concentrations (pKi less than 6.5), suggesting that recognition of 5-HT3 sites might be relevant to part of the in vivo effects of these drugs. Such identical physico-chemical and pharmacological properties of [3H]zacopride specific binding in cortical and NG 108-15 cell membranes strongly suggest that the same 5-HT3 receptor (subtype?) exists in these two preparations.
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PMID:Common pharmacological and physico-chemical properties of 5-HT3 binding sites in the rat cerebral cortex and NG 108-15 clonal cells. 222 9


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