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

Many cells develop an adaptive increase in the capacity of adenylate cyclase to synthesize cyclic AMP (cAMP) after prolonged (hours or days) exposure to drugs which initially inhibit enzyme activity. Recent evidence suggests that adaptive increases in cAMP responses can be induced within minutes by inhibitory drugs. We have investigated the kinetics for induction and decay of this phenomenon in mouse neuroblastoma x rat glioma hybrid cells. The muscarinic cholinergic agonist carbachol induced an increase in prostaglandin E1-stimulated cAMP accumulation within 2 min of pretreatment with carbachol; the increase was 70 to 100% above control values after exposure to carbachol for 30 min. Enhanced cAMP responsiveness decayed with a half-life of about 8 min after removal of carbachol. Pretreatment with carbachol for 30 hr led to an enhanced cAMP response which decayed in two components, a rapid component and an additional, more stable component which persisted for at least 2 hr after withdrawal of carbachol. Pertussis toxin prevented these effects of carbachol. Prevention of carbachol-induced inhibition of cAMP accumulation below basal concentrations with a phosphodiesterase inhibitor did not prevent the ability of carbachol to acutely induce augmented prostaglandin E1-stimulated cAMP accumulation. Mouse neuroblastoma x rat glioma hybrid cells exhibit an enhanced cAMP response after both acute and chronic exposure to a muscarinic cholinergic agonist although these processes decay with different time courses. The signal for this acutely induced adaptation does not appear to be the decrease in cellular cAMP concentration resulting from inhibition of adenylate cyclase but does require a pertussis toxin-sensitive substrate.
 ...
PMID:Activation of muscarinic cholinergic receptors in mouse neuroblastoma x rat glioma hybrid cells: rapid induction of enhanced capacity of prostaglandin E1 receptors to stimulate cyclic AMP accumulation. 215 56

The hypothesis that the small portion of cellular phosphoinositide participating in signal transduction might be preferentially recycled within the plasma membrane was tested in rat glioma (C6) and murine neuroblastoma (N1E-115) cells. Percoll density gradient centrifugation was used to isolate a purified plasma membrane fraction and the subcellular distribution of all enzymes mediating phosphoinositide turnover was assessed. A small but significant proportion of PtdInsP2-specific phosphodiesterase was located in the plasma membrane but only two of the five enzymes required to replace PtdInsP2 (diacylglycerol kinase and PtdInsP kinase) also were present. CTP:phosphatidate cytidylyltransferase and CMP-phosphatidate:inositol phosphatidyltransferase were located exclusively in a microsomal fraction containing enriched levels of endoplasmic reticulum markers. Thus, diacylglycerol from agonist-stimulated cleavage of PtdInsP2, or phosphatidic acid formed from it, must be transferred to the endoplasmic reticulum for conversion to PtdIns. Plasma membrane also lacked PtdIns kinase. If the soluble PtdIns kinase has access to membrane-bound substrate, PtdIns may be phosphorylated to PtdInsP before or during transport to the plasma membrane. Phosphorylation by the predominantly plasma membrane PtdInsP kinase to form PtdInsP2 completes the cycle. PtdInsP phosphatase was present in all membrane fractions suggesting that PtdInsP can be returned to the PtdIns pool in plasma membrane and elsewhere. PtdInsP2 phosphatase was almost exclusively in the cytosol suggesting that reversible interchange between PtdInsP and PtdInsP2 in the plasma membrane may be modulated by the ability of this phosphatase to act on PtdInsP2 in the membrane. Thus, PtdIns resynthesis in the plasma membrane of these cells does not occur and is not required for phosphoinositide-mediated signal transduction.
 ...
PMID:Phosphoinositide metabolism in cultured glioma and neuroblastoma cells: subcellular distribution of enzymes indicate incomplete turnover at the plasma membrane. 215 58

Secretin receptors in membranes from the neuroblastoma-glioma hybrid cell line NG108-15 were investigated by 125I-secretin binding and adenylate cyclase activation. On both parameters the corresponding relative potencies of parent peptides were, respectively: secretin greater than helodermin greater than peptide histidine isoleucinamide = vasoactive intestinal peptide. With secretin analogs and secretin fragments, the order of potency for binding was: secretin = [Val5]secretin greater than [Ala2]secretin = [Ala11]secretin greater than [Ala4, Val5] secretin greater than [Ala4]secretin greater than [D-Phe4] secretin greater than [D-Phe2]secretin = secretin (2-27) greater than secretin (3-27) greater than secretin (7-27). Also, on adenylate cyclase, [D-Phe4]secretin, [D-Phe2]secretin, secretin (2-27) and secretin (3-27) were partial agonists while secretin (7-27) was ineffective. The differentiating agent N6,2'-O-dibutyryladenosine 3',5'-monophosphate (1 mM) increased the density of secretin receptors and secretin-stimulated adenylate cyclase activity after a lag period of 4 h. After incubation for 24 h, receptor number and enzyme activity were increased 4- and 3-fold, respectively. These effects were inhibited totally by 1 microgram/ml cycloheximide and halved by 5 micrograms/ml actinomycin D. They were mimicked by 1 mM sodium butyrate but were not reproduced by either 8-bromoadenosine 3',5'-monophosphate or the phosphodiesterase inhibitor rac-4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone.
 ...
PMID:Secretin receptors in the neuroglioma hybrid cell line NG108-15. Characterization and regulation of their expression. 217 30

The role of cyclic nucleotides in modulating acetylcholine-induced and dopamine-induced responses was examined with cultured neuroblastoma N1E-115 cells by means of intracellular recording techniques. Acetylcholine-induced muscarinic hyperpolarization and muscarinic depolarization were potentiated by bath application of a dibutyryl analog of adenosine 3',5'-phosphate (cyclic AMP) or phosphodiesterase inhibitors, 3-isobutyl-1-methylxanthine and 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone. Dibutyryl cyclic AMP did not affect the resting membrane potential and membrane resistance. Acetylcholine-induced nicotinic depolarization was unaffected by dibutyryl cyclic AMP or phosphodiesterase inhibitors. Intracellular pressure injection of cyclic AMP caused a potentiation of muscarinic hyperpolarization and muscarinic depolarization without marked change in the resting membrane potential. Nicotinic depolarization and dopamine depolarization were not affected by cyclic AMP injection. Among the possible metabolites of cyclic AMP, injection of adenosine potentiated muscarinic hyperpolarization, but did not change nicotinic depolarization and dopamine depolarization. Injection of guanosine 3',5'-phosphate (cyclic GMP) potentiated muscarinic hyperpolarization and muscarinic depolarization without effect on nicotinic depolarization and dopamine depolarization. We conclude that cyclic AMP and cyclic GMP enhance muscarinic responses in neuroblastoma cells. It is suggested that synaptic transmission in the nervous system may be modulated postsynaptically by changes in intracellular cyclic nucleotide levels.
 ...
PMID:Cyclic nucleotide potentiation of muscarinic responses in neuroblastoma cells. 243 3

The rates of phosphodiesterase-promoted hydrolysis of cGMP and cAMP have been measured in intact neuroblastoma N1E-115 cells by determining rates of 18O incorporation from 18O-water into the alpha-phosphoryls of guanine and adenine nucleotides. The basal rate of guanine nucleotide alpha-phosphoryl labeling ranged from 180 to 244 pmol X mg protein-1 X min-1. Sodium nitroprusside (SNP) caused a sustained 3.4-fold increase in this 18O-labeling rate in conjunction with 28- and 50-fold increases in cellular cGMP concentration at 3 and 6 min, respectively. This 18O-labeling rate (795 pmol X mg protein-1 X min-1) corresponded with the sum of the low (1.7 microM) and high (34 microM) Km phosphodiesterase activities assayable in cell lysates which exhibited a combined maximum velocity of 808 pmol X mg protein-1 X min-1 to which the high Km species contributed 84%. This information and the characteristics of the profile of 18O-labeled molecular species indicate that cGMP metabolism was restricted to a very discrete cellular compartment(s) of approximately 12% of the cell volume. Carbachol (1 mM) produced a transient increase (6-fold) in cellular cGMP concentration and a transient increase (90%) in the rate of 18O labeling of alpha-GTP during the first minute of treatment which translates into 30 additional cellular pools of cGMP hydrolyzed in this period. IBMX (1 mM) produced a relatively rapid increase in cellular cGMP (3- to 5-fold) and cAMP (2-fold) concentrations and a delayed inhibition of 18O labeling of guanine and adenine nucleotide alpha-phosphoryls without further elevation of cyclic nucleotide levels. These results indicate that besides inhibiting cyclic nucleotide hydrolysis, IBMX also imparts a time-dependent inhibitory influence on the generation of cyclic nucleotides. The data obtained show that measurement of 18O labeling of guanine and adenine nucleotide alpha-phosphoryls combined with measurements of cyclic nucleotide steady state levels provides a means to assess the rates of cyclic nucleotide synthesis and hydrolysis within intact cells and to identify the site(s) of action of agents that alter cellular cyclic nucleotide metabolism.
 ...
PMID:The dynamics of cGMP metabolism in neuroblastoma N1E-115 cells determined by 18O labeling of guanine nucleotide alpha-phosphoryls. 243 34

Mouse neuroblastoma X embryonic Chinese hamster brain explant hybrid cell line (NCB-20) forms functional synapses when intracellular cyclic AMP levels are elevated for a prolonged period of time. NCB-20 cells were labeled with [32P]orthophosphate under conditions where 2-chloroadenosine gave maximum increases of 32P incorporation into tyrosine hydroxylase in nerve growth factor dibutyryl cyclic AMP-differentiated PC12 (pheochromocytoma) cells. When NCB-20 cells were exposed to activators [5-hydroxytryptamine (5-HT), prostaglandin E1, or forskolin], resulting in activation of cyclic AMP-dependent protein kinase, increased 32P incorporation into two major proteins [130 kilodaltons (kDa) and 90 kDa] occurred. 5-HT (in the presence of phosphodiesterase inhibitor, isobutylmethylxanthine) gave a three- to fourfold increase, and forskolin a four- to sevenfold increase in 32P incorporation into the 90-kDa protein. [D-Ala2,D-Leu5]-enkephalin, which decreased cyclic AMP levels and reversed the 2-chloroadenosine-stimulated phosphorylation of tyrosine hydroxylase in differentiated PC12 cells, also reversed the stimulation of phosphorylation of the 90-kDa protein in NCB-20 cells. Pretreatment of NCB-20 cells with a calcium ionophore, A23187, gave increased phosphorylation of the 90- and 130-kDa proteins, but phorbol esters such as 12-O-tetradecanoylphorbol 13-acetate (tumor promoting agent), cell depolarization with high K+, or pretreatment with dibutyryl cyclic GMP had no effect on phosphorylation of these proteins. In contrast, phosphorylation of an 80-kDa protein was decreased by forskolin, but increased following activation of the calcium/phospholipid-dependent kinase with tumor promoting agent. Neither the 90-kDa nor the 80-kDa protein showed any immunological cross-reactivity with synapsin, a major synaptic protein known to be phosphorylated by cyclic AMP-dependent protein kinase and calcium/calmodulin-dependent protein kinase, but not calcium/phospholipid-dependent protein kinase. This suggests that in NCB-20 cells, several unique proteins can be phosphorylated by cyclic AMP-dependent protein kinase in response to hormonal elevation of cyclic AMP levels. In contrast, an 80-kDa protein is the primary substrate for calcium/phospholipid-dependent protein kinase, and its phosphorylation is inhibited by agents that elevate cyclic AMP levels and thereby activate cyclic AMP-dependent protein kinase.
 ...
PMID:Neuromodulator-mediated phosphorylation of specific proteins in a neurotumor hybrid cell line (NCB-20). 245 Jan 74

The possibility that an increased intracellular concentration of cyclic AMP (cAMP) can regulate the extent of muscarinic receptor-stimulated phosphoinositide (PPI) turnover in the human neuroblastoma cell line SK-N-SH was examined. Addition of either forskolin (or its water-soluble analog, L-85,8051), theophylline, isobutylmethylxanthine, or cholera toxin, agents that interact with either the catalytic unit of adenylate cyclase, cAMP phosphodiesterase, or the guanine nucleotide binding protein linked to adenylate cyclase activation, resulted in a 45-181% increase in cAMP concentration and a 27-70% inhibition of carbachol-stimulated inositol phosphate release. Through the use of digitonin-permeabilized cells, the site of inhibition was localized to a step at, or distal to, the guanine nucleotide binding protein that regulates phospholipase C activity. In contrast, when intact SK-N-SH cells were exposed to prostaglandin E1, the ensuing increases in cAMP were not accompanied by an inhibition of stimulated PPI turnover. These differential effects of increased cAMP concentrations on stimulated PPI turnover may reflect the compartmentation of cAMP within SK-N-SH cells.
 ...
PMID:Muscarinic receptor-stimulated phosphoinositide turnover in human SK-N-SH neuroblastoma cells: differential inhibition by agents that elevate cyclic AMP. 247 99

Calmodulin (CaM)-dependent enzymes, such as CaM-dependent phosphodiesterase (CaM-PDE), CaM-dependent protein phosphatase (CN), and CaM-dependent protein kinase II (CaM kinase II), are found in high concentrations in differentiated mammalian neurons. In order to determine whether neuroblastoma cells express these CaM-dependent enzymes as a consequence of cellular differentiation, a series of experiments was performed on human SMS-KCNR neuroblastoma cells; these cells morphologically differentiate in response to retinoic acid and phorbol esters [12-O-tetradecanoylphorbol 13-acetate (TPA)]. Using biotinylated CaM overlay procedures, immunoblotting, and protein phosphorylation assays, we found that SMS-KCNR cells expressed CN and CaM-PDE, but did not appear to have other neuronal CaM-binding proteins. Exposure to retinoic acid, TPA, or conditioned media from human HTB-14 glioma cells did not markedly alter the expression of CaM-binding proteins; 21-day treatment with retinoic acid, however, did induce expression of novel CaM-binding proteins of 74 and 76 kilodaltons. Using affinity-purified polyclonal antibodies, CaM-PDE immunoreactivity was detected as a 75-kilodalton peptide in undifferentiated cells, but as a 61-kilodalton peptide in differentiated cells. CaM kinase II activity and subunit autophosphorylation was not evident in either undifferentiated or neurite-bearing cells; however, CaM-dependent phosphatase activity was seen. Immunoblot analysis with affinity-purified antibodies against CN indicated that this enzyme was present in SMS-KCNR cells regardless of their state of differentiation. Although SMS-KCNR cells did not show a complete pattern of neuronal CaM-binding proteins, particularly because CaM kinase II activity was lacking, they may be useful models for examination of CaM-PDE and CN expression. It is possible that CaM-dependent enzymes can be used as sensitive markers for terminal neuronal differentiation.
 ...
PMID:Expression of calmodulin-dependent phosphodiesterase, calmodulin-dependent protein phosphatase, and other calmodulin-binding proteins in human SMS-KCNR neuroblastoma cells. 254 Feb 70

Phosphoinositide and inositol metabolism was compared in glioma (C6), neuroblastoma (N1E-115) and neuroblastoma X glioma hybrid (NG 108-15) cells. All cell lines had similar proportions of phosphatidylinositol (PI), phosphatidylinositol 4-phosphate (PIP), and phosphatidylinositol 4,5-bisphosphate (PIP2). Neuroblastoma and hybrid cells had almost identical phospholipid and phosphoinositide compositions and similar activities for the enzymes metabolizing polyphosphoinositides (PI kinase, PIP phosphatase, PIP kinase, PIP2 phosphatase, PIP2 phosphodiesterase). Glioma cells differed by having greater proportions of ethanolamine plasmalogen and sphingomyelin, lower PIP kinase, 3-5-fold higher PIP phosphatase activity and 10-15-fold greater PIP2 phosphodiesterase activity. Higher PIP phosphatase and PIP2 diesterase activities appear to be characteristic of cells of glial origin, since similar activities were found in primary cultures of astroglia. Glioma cells also metabolize inositol differently. In pulse and pulse-chase experiments, glioma cells transported inositol into a much larger water-soluble intracellular pool and maintained a concentration gradient 30-times greater than neuroblastoma cells. Label in intracellular inositol was less than in phosphoinositides in neuroblastoma and exchanged rapidly with extracellular inositol. In glioma, labeling of intracellular inositol greatly exceeded that of phosphoinositides. As a consequence, radioactivity in prelabeled phosphoinositides could not be effectively chased from glioma cells by excess unlabeled inositol. Such differences between cells of neuronal and glial origin suggest different and possibly supportive roles for these two cell types in maintaining functions regulated through phosphoinositide-linked signalling systems in the central nervous system.
 ...
PMID:Differences in the metabolism of inositol and phosphoinositides by cultured cells of neuronal and glial origin. 254 91

Differentiation in the mouse neuroblastoma cells is induced by cAMP and is characterized by neurite extension and increased acetylcholinesterase, cAMP-phosphodiesterase, and RI cAMP-binding activities. To gain a better understanding of the regulation of expression and the possible function of the RI cAMP-binding protein in neuroblastoma cell differentiation, we evaluate the specificity of action of cAMP analogues and agents that increased intracellular cAMP concentration in the induction of the 47,000-dalton RI protein. The amount of RI in cell extracts was quantitated by the photoactivated incorporation of 8-N3-[32P]cAMP into the 47,000-dalton RI and by ELISA and Western blot techniques. Our results showed that dibutyryl cAMP, forskolin, prostaglandin E1, 3-isobutyl-1-methyl xanthine, and papavarine gave a 2- to 4-fold increase in the RI cAMP-binding protein coincident with the expression of various morphological and biochemical differentiation phenotypes in the mouse neuroblastoma cells. However, the effects of 8-bromo-cAMP were different. 8-Bromo-cAMP effectively promoted neurite extension and increased acetylcholinesterase and cAMP-phosphodiesterase activities; however, there was no concomitant increase in the RI cAMP-binding protein. The result raises interesting questions concerning the coupling of expression of the various differentiation phenotypes in the mouse neuroblastoma cells.
 ...
PMID:Specificity of the action of cAMP agonists in the induction of RI cAMP-binding protein in mouse neuroblastoma cells. 283 19


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>