UMLS:C0027819 - FACTA Search

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Query: UMLS:C0027819 (neuroblastoma)
27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Early postnatal mouse dorsal root ganglion neurons were found to express several glycosylphosphatidylinositol-anchored (GPI) molecules from the immunoglobulin superfamily (neural cell adhesion molecule 120 kD isoform, F3, Thy1) whose expression is developmentally regulated. A hybrid cell line (ND26), made by fusing postmitotic rat dorsal root ganglion (DRG) neurons with the mouse neuroblastoma N18Tg2, could be induced to differentiate by manipulating the composition of the culture medium and expressed similar GPI molecules to DRG neurons. We used this model system to investigate the metabolism of GPI-anchored molecules. We found that neural cell adhesion molecule 120 Kd isoform expression decreased upon differentiation, whereas the level of F3 and Thy1 increased, suggesting a role in neurite outgrowth processes. The ratio of molecules cleavable by exogenous phosphatidylinositol phospholipase C (PI-PLC) was similar for all the GPI-anchored molecules, which could mean that cell-specific modifications of the basic anchoring structure determine the level of potentially releasable molecules. Measurements of spontaneous release indicated that this reflected the overall level of expression of these molecules by the ND26 cell line. Finally, we observed an effect of dibutyryl cAMP on the level of expression of F3 and Thy1 but not of N-CAM. However, we could not detect any significant effect of nerve growth factor (NGF) either on the level of expression or on the amount of spontaneously released molecules.
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PMID:Expression and release of phosphatidylinositol anchored cell surface molecules by a cell line derived from sensory neurons. 134 92

Nine distinct alpha subunits of guanine nucleotide binding proteins (G-proteins) have now been identified by cDNA cloning. Each of these functions to allow transduction of information between hormone-activated receptors in the plasma membrane and effector systems which are either ion channels or enzymes which regulate the intracellular concentration of second messengers. As the individual G-proteins are highly similar in primary sequence, it is pertinent to ask what degree of specificity of interaction each of these display with the various receptors and effector systems. Specificity of tissue location defines that the rod and cone transducins (TD1 and TD2, respectively) act as the coupling proteins between rhodopsin and cone opsins and their cyclic nucleotide phosphodiesterase effectors and that G(olf) is the G-protein which tranduces signals from odorant receptors to adenylate cyclase in olfactory sensory neurones. However, many of the other identified G-proteins are co-expressed in a single tissue or cell. Whilst sensitivity to ADP-ribosylation catalysed by bacterial toxins from Bordetella pertussis and Vibrio cholerae has allowed a further subdivision of the G-protein family, this approach is limited as these toxins have multiple G-protein substrates. As the extreme C-terminus of the alpha subunit of each G-protein appears to be a key domain for the interactions of receptors and G-proteins we have generated a series of G-protein-selective antipeptide antisera against this region and then have used these antisera to attempt to interfere with receptor-G-protein coupling. With this approach we have been able to demonstrate that a delta opioid receptor-mediated inhibition of adenylate cyclase in neuroblastoma x glioma, NG108-15, cell membranes is transduced specifically by Gi2 and in the same cell that alpha 2 adrenergic inhibition of Ca2+ currents is transduced by Go. Similar strategies are likely to be of universal significance, for example in the identification of the G-protein (Gp) which regulates the receptor-mediated activation of phosphoinositidase C. Methods to allow pharmacological manipulation of the levels of expression of various G-proteins in the membranes of cells are also discussed. Such approaches are also likely to assist in the identification of G-proteins of defined functions.
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PMID:The role and specificity of guanine nucleotide binding proteins in receptor-effector coupling. 196 33

The net content of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] was measured in bradykinin (BK)-stimulated NIH3T3 fibroblasts and neuroblastoma-glioma hybrid cells (NG108-15). BK-mediated production of Ins(1,4,5)P3 was not affected by replacing the medium with Ca2+-free medium, but addition of EGTA (1mM) to Ca2+-free medium markedly prevented production of Ins(1,4,5)P3. Although pertussis toxin (PT) treatment caused ADP-ribosylation in both NIH3T3 cells and NG108-15 cells, the BK-induced Ins(1,4,5)P3 formation was considerably reduced in the former cells but not in the latter cells, suggesting that PT-sensitive and PT-insensitive GTP-binding proteins are involved in phosphoinositide phospholipase C (PI-PLC) activation in fibroblasts and neuroblastoma cells, respectively. In NG108-15 cells down-regulated in protein kinase C (PKC) by long-term exposure to phorbol 12-myristate 13-acetate (PMA), BK-stimulated Ins(1,4,5)P3 accumulation was significantly enhanced compared to control cells.
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PMID:Bradykinin-induced generation of inositol 1,4,5-trisphosphate in fibroblasts and neuroblastoma cells: effect of pertussis toxin, extracellular calcium, and down-regulation of protein kinase C. 284 40

Measurement of the intracellular Ca2+ concentration ([Ca2+]i) in fura-2-loaded single cells of the human neuroblastoma line SH-SY5Y indicated coexpression of muscarinic and bradykinin receptors linked to activation of phosphoinositidase C (PIC). Both agonists elevated [Ca2+]i and inositol-1,4,5-trisphosphate [Ins(1,4,5)P3] levels in populations of adherent cells, although in cells used directly upon attainment of confluence the responses to carbachol were greater than those to bradykinin and displayed additional sustained components. This model system was used to examine heterologous interactions when a second PIC-linked agonist was added 100-300 sec after but in the continued presence of the first. Maximal (1 mM) carbachol concentrations abolished the elevation of [Ca2+]i produced by bradykinin but the muscarinic antagonist atropine (10 microM) restored the response, provided that extracellular Ca2+ was present throughout the experiment or was added before bradykinin. Carbachol also abolished bradykinin-mediated Ins(1,4,5)P3 elevation. In contrast, bradykinin did not influence [Ca2+]i or Ins(1,4,5)P3 responses to carbachol in the presence of extracellular Ca2+. In cells maintained at confluence for 2 weeks, the rapid peak elevations of [Ca2+]i and Ins(1,4,5)P3 levels induced by carbachol and bradykinin were approximately equivalent in magnitude. In these cells carbachol again abolished bradykinin-mediated elevation of [Ca2+]i but only attenuated, rather than abolished, the elevation of Ins(1,4,5)P3 levels. The [Ca2+]i and Ins(1,4,5)P3 responses to bradykinin were fully restored 100 sec after atropine only in the presence of extracellular Ca2+. Thus, depletion of an intracellular Ins(1,4,5)P3-sensitive Ca2+ store may underlie the ability of carbachol to produce not only heterologous desensitization of the [Ca2+]i elevation induced by bradykinin but also that of the Ins(1,4,5)P3 response. This suggests a feed-forward activation of PIC by Ca2+ released from Ins(1,4,5)P3-sensitive stores. Furthermore, studies in which Ins(1,4,5)P3-sensitive stores were depleted with thapsigargin and cells were challenged in the presence or absence of extracellular Ca2+ indicated that Ca2+, irrespective of its origin (intra- or extracellular), potentiated the Ins(1,4,5)P3 response to bradykinin alone. In cells maintained at confluence for 2 weeks, bradykinin was again unable to influence either [Ca2+]i or Ins(1,4,5)P3 responses to carbachol in the presence of Ca2+. This lack of heterologous desensitization may be due to the rapid, full, homologous desensitization of bradykinin receptors, compared with an incomplete homologous desensitization of muscarinic receptors.
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PMID:Heterologous desensitization of both phosphoinositide and Ca2+ signaling in SH-SY5Y neuroblastoma cells: a role for intracellular Ca2+ store depletion? 770 Feb 49

Electrically permeabilized SH-SY5Y neuroblastoma cells have been used to examine the relationship between receptor occupation by muscarinic agonists, inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) accumulation and Ca2+ mobilization from intracellular stores. The kinetics, concentration-dependence and guanine nucleotide-sensitivity of these responses have been characterized for the agonists, carbachol, arecoline and oxotremorine. Carbachol stimulated Ins(1,4,5)P3 accumulation and Ca2+ mobilization with an EC50 value approximately 50 microM, only slightly lower than the apparent affinity of this agonist for the "free" receptor (100 microM). Arecoline and oxotremorine were partial agonists, mobilizing 45 and 21% of the Ca2+ mobilized by carbachol, and yielded EC50 values for both Ins(1,4,5)P3 and Ca2+ responses, similar to their binding affinity. Guanosine 5'-O-3 thio-triphosphate (GTP gamma S) markedly enhanced the responses elicited by all three agonists. Carbachol became significantly more potent for both Ins(1,4,5)P3 accumulation (EC50 = 4.1 microM) and Ca2+ mobilization (EC50 = 0.25 microM), revealing a separation of the dose-response relationships. GTP gamma S caused a smaller separation of the responses elicited by arecoline (Ca2+ mobilization EC50 = 0.9 microM; Ins(1,4,5)P3 accumulation EC50 = 3.6 microM), and only enhanced maximal responses for oxotremorine. These data reveal that the functional coupling of muscarinic receptors to activation of phosphoinositidase C and subsequent Ca2+ mobilization from intracellular stores is maintained after electrical permeabilization. Furthermore, this model has been used to reveal differences in the relative activities of muscarinic agonists and how they are influenced by a hydrolysis-resistant guanine nucleotide.
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PMID:A comparison between muscarinic receptor occupancy, inositol 1,4,5-trisphosphate accumulation and Ca2+ mobilization in permeabilized SH-SY5Y neuroblastoma cells. 796 2

The phosphoinositidase C-linked G proteins Gq alpha and G11 alpha are highly similar and comigrate in 10% (w/v) acrylamide SDS-PAGE. Antisera generated against regions common between these G proteins thus detect a composite of the two polypeptides following resolution in such gels. Using SDS-PAGE conditions which allow resolution of Gq alpha and G11 alpha in rodent brain and neuroblastoma cell lines it was observed that primate frontal cortex and neuroblastoma cell lines did not express a polypeptide which comigrated with rodent G11 alpha. Species diversity in G-protein sequences is extremely limited; however, immunoblotting primate cells and frontal cortex with a G11 alpha-specific antiserum demonstrated this to be due to a difference in mobility of rodent and primate G11 alpha under these conditions rather than lack of expression of G11 alpha by primates. A cDNA encoding mouse G11 alpha was transiently expressed in monkey COS-1 cells and membranes from these cells were immunoblotted with antisera able to identify primate and rodent G11 alpha equally, following SDS-PAGE under the resolving conditions. Both mouse and monkey G11 alpha could be detected concurrently and unambiguously following transfection. This is the first demonstration that species variants of the same G protein expressed in a single cell can be detected simultaneously.
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PMID:Concurrent specific immunological detection of both primate and rodent forms of the guanine nucleotide binding protein G11 alpha following their coexpression. 803 5

Stimulation of SH-SY5Y human neuroblastoma cells with carbachol, a muscarinic agonist, down-regulates the type I inositol 1,4,5-trisphosphate (InsP3) receptor by > 90% with maximal and half-maximal effects after approximately 6 h and approximately 1 h, respectively. Examination of the mechanistic basis of this down-regulation revealed that carbachol increased the rate of type I InsP3 receptor degradation (radiolabeled immunoprecipitable receptor was lost from cells with half-times of > 8 h and approximately 1 h in the absence and presence of carbachol, respectively) and that the concentration of type I InsP3 receptor mRNA, despite a transient decrease after 3 h, did not correlate with levels of the receptor. Only those muscarinic receptor subtypes coupled to stimulation of phosphoinositide hydrolysis were capable of causing type I InsP3 receptor down-regulation. Ca2+ mobilization was pivotal to the mechanisms of receptor down-regulation, since perturbation of Ca2+ homeostasis with either EGTA or thapsigargin blocked the ability of carbachol to accelerate receptor degradation. Studies with thapsigargin also revealed that both functional InsP3-sensitive Ca2+ stores and persistent elevation of InsP3 concentration were required for down-regulation to occur. In conclusion, phosphoinositidase C-linked muscarinic receptors down-regulate the type I InsP3 receptor by accelerating its degradation. It appears that this process is initiated by persistent discharge of intracellular Ca2+ stores via the channels formed by tetramerically complexed type I InsP3 receptors.
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PMID:Muscarinic receptor activation down-regulates the type I inositol 1,4,5-trisphosphate receptor by accelerating its degradation. 813 16

Stimulation of muscarinic receptors expressed in SH-SY5Y human neuroblastoma cells resulted in a complex profile of inositol 1,4,5-trisphosphate (InsP3) accumulation, with a dramatic increase (six- to eightfold) over the first 10 s (the "peak" phase) and subsequently from approximately 60 s onward, maintained at a lower but sustained level (the "plateau" phase). Chelation of extracellular Ca2+ with EGTA or inhibition of Ca2+ channels with Ni2+ showed that the plateau phase was dependent upon Ca2+ entry. Furthermore, use of thapsigargin and EGTA to discharge and sequester Ca2+ from intracellular stores revealed that Ca2+ from this source was capable of supporting the peak phase of the InsP3 response. Carbachol-stimulated phosphoinositidase C activity in permeabilized SH-SY5Y cells was also shown to be highly dependent on free Ca2+ concentration (20-100 nM) and suggests that under normal conditions, InsP3 formation is enhanced by increases in cytosolic free Ca2+ concentration that accompany muscarinic receptor activation. Measurement of carbachol-stimulated total inositol phosphate accumulation in the presence of Li+ indicated that the initial rate of phosphoinositide hydrolysis (from 0 to 30 s) was about fivefold greater than that from 30 to 300 s. This rapid but partial desensitization of receptor-mediated phosphoinositide hydrolysis provides strong evidence for the mechanism underlying the changes in InsP3 accumulation over this time. Because very similar data were obtained in Chinese hamster ovary cells transfected with human m3 receptor cDNA, we suggest that although increases in cytosolic free CA2+ concentration amplify InsP3 formation during stimulation of m3 muscarinic receptors, the primary factor that governs the profile of InsP3 accumulation is rapid, but partial, desensitization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Muscarinic receptor-mediated inositol 1,4,5-trisphosphate formation in SH-SY5Y neuroblastoma cells is regulated acutely by cytosolic Ca2+ and by rapid desensitization. 820 26

The effects of protein kinase C (PKC) activation on muscarinic receptor-mediated phosphoinositide and Ca2+ signalling were examined in the human neuroblastoma, SH-SY5Y. Carbachol evoked rapid transient elevations of Ins(1,4,5)P3 and intracellular [Ca2+] followed by lower sustained elevations. Phorbol 12,13-dibutyrate (PDBu) preferentially attenuated transient phases. Removal of the transplasmalemmal Ca2+ gradient coupled with depletion of intracellular Ca2+ stores with thapsigargin also reduced carbachol-mediated Ins(1,4,5)P3 accumulation. Under these conditions, PDBu virtually abolished Ins(1,4,5)P3 responses to carbachol thereby implicating both Ca(2+)- and PKC-sensitive components. PDBu also reduced agonist-mediated accumulation of inositol phosphates and depletion of lipids, thereby eliminating an effect of PKC on Ins(1,4,5)P3 metabolism or phosphoinositide synthesis. In electroporated cells, PDBu inhibited Ins(1,4,5)P3 accumulation mediated by carbachol or guanosine 5'-[gamma-thio]-triphosphate, the latter indicating that some PDBu-sensitive elements were downstream of the receptor. The PKC inhibitor, Ro-318220, protected against PDBu but did not enhance responses to maximal concentrations of carbachol, indicating no feedback inhibition by agonist-activated PKC. Muscarinic antagonist activity of Ro-318220 complicated such assessment at low agonist concentrations. Carbachol or PDBu induced cytosol to membrane translocation of PKC alpha. This was faster and possibly greater with PDBu, which may explain the lack of feedback by agonist-activated PKC. These results indicate that, in SH-SY5Y cells, PDBu activation of PKC preferentially inhibits rapid muscarinic receptor-mediated phosphoinositide and Ca2+ responses via suppression of PtdIns(4,5)P2 hydrolysis. This is at least partially through inhibition of Gq-protein/phosphoinositidase C coupling. However, at least at high agonist concentrations, a major agonist-mediated PKC feedback is not present in these cells.
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PMID:Contrasting effects of phorbol ester and agonist-mediated activation of protein kinase C on phosphoinositide and Ca2+ signalling in a human neuroblastoma. 867 Jan 70

SH-SY5Y human neuroblastoma cells express muscarinic M3 receptors as well as insulin receptors, thus offering the opportunity to investigate possible cross-talk following activation of two distinct intracellular signal transduction pathways that convert the precursor phosphatidylinositol (PI) to its 3' phosphate or its 4' phosphate, respectively. In this study, the effect of carbachol on insulin-stimulated PI 3-kinase (PI3K) activity was examined in SH-SY5Y cells. Insulin addition to the cell medium induced a 10-26-fold increase in anti-phosphotyrosine-immunoprecipitable PI3K activity. Preincubation with 1 mM carbachol inhibited the insulin-stimulated PI3K activity in a time-dependent manner, with half-maximal and maximal inhibition times of 4 and 15 min, respectively. Atropine blocked the inhibitory effect of carbachol. Although carbachol did not change the amount of 85-kDa subunit protein regulatory unit associated with tyrosine-phosphorylated proteins, either in control or in insulin-stimulated cells, it appears to decrease the amount of associated 110-kDa catalytic subunit protein in the latter instance. Because PI3K activity from SH-SY5Y cells has been shown to be inhibited in vitro in the presence of cytidine diphosphodiacylglycerol (CDP-DAG) or phosphatidate (PA), we examined the presence of these lipids in SH-SY5Y cells that had been treated with carbachol. Formation of both lipids was increased in a time-dependent manner following carbachol addition, and their increased levels are proposed to account for the observed in vivo inhibition of PI3K. Addition of the cell-permeable homologue didecanoyl-CDP-DAG to intact cells inhibited insulin-stimulated PI3K activity up to 75%, with an IC50 of 0.5 microM, a result that further supports a proposed lipid-mediated inhibition of PI3K. Exogenously added didecanoyl-PA, however, did not affect PI3K activity. The possibility that stimulation of the PI 4-kinase-mediated signal transduction pathway leads to down-regulation of the PI3K-mediated signal transduction pathway in vivo, via inhibition of PI3K by CDP-DAG or by other consequences of phosphoinositidase C-linked receptor activation, is discussed.
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PMID:Carbachol inhibits insulin-stimulated phosphatidylinositol 3-kinase activity in SH-SY5Y neuroblastoma cells. 875 32

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