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

An intracellular (ATP + Mg2+)-dependent Ca2+ pumping mechanism has been identified and characterized within the cultured clonal neuroblastoma cell line N1E-115. Using cell suspensions treated with 0.005% saponin which selectively permeabilizes the plasma membrane in 95-98% of the cells, it was possible to show clearly that the intracellular Ca2+ pump mechanism is of non-plasma membrane origin and therefore can be compared directly with the Ca2+ pump characterized in detail in synaptosomal membrane vesicles (Gill, D. L., Grollman, E. F., and Kohn, L. D. (1981) J. Biol. Chem. 256, 184-192; Gill, D. L., Chueh, S. H., and Whitlow, C. L. (1984) J. Biol. Chem. 259, 10807-10813) which was proven by flux reversal studies to be derived from the neural plasma membrane (Gill, D. L. (1982) J. Biol. Chem. 257, 10986-10990). The intracellular Ca2+ pump in N1E-115 cells is distinct from mitochondrial Ca2+ accumulation and is increased up to 8-fold higher as cells reach confluency. In similarity to the neural plasma membrane pump, the intracellular Ca2+ pump within N1E-115 cells has high affinity for Ca2+ (Km = 0.28 microM), is dependent on both ATP (Km = 26 microM) and either Mg2+ or Mn2+ which half-maximally activate Ca2+ pumping at 0.35 mM and 0.32 mM, respectively, and shows similar specificity for Sr2+ and Ba2+ which half-maximally inhibit Ca2+ transport at 50 microM and 1.5 mM, respectively. In contrast to the neural plasma membrane pump, the intracellular Ca2+ pump displays approximately 40-fold higher sensitivity to La3+ (IC50 = 5 microM) and an apparent 400-fold lower sensitivity to VO4(3-) (IC50 = 185 microM), although the inhibitory effectiveness of VO4(3-) is increased 37-fold by a 15-min preincubation of the permeabilized cells with VO4(3-) in the absence of ATP (apparent IC50 = 5 microM). In further contrast to the neural plasma membrane Ca2+ pump, the intracellular pump within N1E-115 cells is stimulated more than 20-fold by oxalate (giving prolonged linear Ca2+ accumulation), is resistant to low saponin concentrations, and is not modified by calmodulin even after extensive treatment with ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and/or calmodulin antagonist drugs. However, calmidazolium is effective in inhibiting the intracellular Ca2+ pump with an IC50 of approximately 2 microM.
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PMID:An intracellular (ATP + Mg2+)-dependent calcium pump within the N1E-115 neuronal cell line. 316 Jun 97

A kinetic analysis of the tyrosine-specific protein kinase of pp60c-src from the C1300 mouse neuroblastoma cell line Neuro-2A and pp60c-src expressed in fibroblasts was carried out to determine the nature of the increased specific activity of the neuroblastoma enzyme. In immune-complex kinase assays with ATP-Mn2+ and the tyrosine-containing peptide angiotensin I as phosphoacceptor substrate, pp60c-src from the neuroblastoma cell line was characterized by a maximum velocity (Vmax.) that was 7-15-fold greater than the Vmax. of pp60c-src from fibroblasts. The neuroblastoma enzyme exhibited Km values for ATP (16 +/- 3 microM) and angiotensin I (6.8 +/- 2.6 mM) that were similar to Km values for ATP (25 +/- 3 microM) and angiotensin I (6.5 +/- 1.7 mM) of pp60c-src from fibroblasts. pp60v-src expressed in Rous-sarcoma-virus-transformed cells exhibited an ATP Km value (25 +/- 4 microM) and an angiotensin I Km value (6.6 +/- 0.5 mM) that approximated the values determined for pp60c-src in neuroblastoma cells and fibroblasts. These results indicate that the pp60c-src kinase from neuroblastoma cells has a higher turnover number than pp60c-src kinase from fibroblasts, and that the neural form of the enzyme would be expected to exhibit increased catalytic activity at the saturating concentrations of ATP that are found intracellularly.
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PMID:Vmax. activation of pp60c-src tyrosine kinase from neuroblastoma neuro-2A. 332 40

The voltage-dependent Na+ ionophore of various neuronal cells is permeable not only to Na+ ions but also to guanidinium ions. Therefore, the veratridine- (or aconitine-)stimulated influx of [14C]guanidinium in neuroblastoma x glioma hybrid cells was measured to characterize the Na+ ionophore of these cells. Half-maximal stimulation of guanidinium uptake was seen at 30 microM veratridine. At 1 mM guanidinium, the veratridine-stimulated uptake of guanidinium was lowered to 50% by approximately 60 mM Li+, Na+, or K+ and by a few millimolar Mn2+, Co2+, or Ni2+. The basal, as well as the veratridine-stimulated, uptake of guanidinium was inhibited by the cholinergic antagonists (+)-tubocurarine (Ki = 50 to 500 nM) and atropine (Ki = 5 to 30 microM) and the adrenergic antagonists phentolamine (Ki = 5 microM) and propranolol (Ki = 60 microM). The specificity of the inhibitory effects of these agents is stressed by the ineffectiveness of various other neurotransmitter antagonists. However, the corresponding ionophore in neuroblastoma cells (clone N1E-115) seems to be regulated differently. While phentolamine and propranolol inhibit the veratridine-activated uptake as in the hybrid cells, (+)-tubocurarine and atropine exert only a slight effect.
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PMID:Blockade by neurotransmitter antagonists of veratridine-activated ion channels in neuronal cell lines. 613 Jan 27

Guanylate cyclase was activated 3- to 10-fold by hemin in a dose-dependent manner in membranes prepared from homogenates of rat lung, C6 rat glioma cells, or B103 rat neuroblastoma cells. Maximum activation was observed with 50 to 100 microM hemin with higher concentrations being inhibitory. Activation was observed when Mg2+-GTP but not when Mn2+-GTP was used as the substrate. Increased enzyme activity reflected selective activation of the particulate form of guanylate cyclase; hemin inhibited the soluble form of guanylate cyclase 70 to 90% over a wide range of concentrations. Activation was not secondary to proteolysis since a variety of protease inhibitors failed to alter stimulation by hemin. Protophorphyrin IX had little effect on particulate guanylate cyclase activity and sodium borohydride almost completely abolished hemin-dependent activation. These data suggest a requirement for the ferric form of the porphyrin-metal chelate for activation. However, agents which interact with the iron nucleus of porphyrins, such as cyanide, had little effect on the ability of hemin to activate guanylate cyclase. The stimulatory effects of hemin were observed in the presence of detergents such as Lubrol-PX, and highly purified particulate enzyme could be activated to the same extent as enzyme in native membranes. These data suggest that the interaction of porphyrins with particulate guanylate cyclase is complex in nature and different from that with the soluble enzyme.
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PMID:Selective activation of particulate guanylate cyclase by a specific class of porphyrins. 614 94

Incubation of mouse neuroblastoma cells (clone N1E-115) with Mn2+ resulted in a rapid and transient increase in cyclic GMP formation. This effect appears to be due to an increase in calcium influx because it did not occur in the absence of extracellular calcium or in the presence of verapamil, a calcium transport inhibitor. In addition, Mn2+ inhibited muscarinic receptor-mediated cyclic GMP responses. The ability of Mn2+ to increase cyclic GMP levels was markedly diminished in cells desensitized to the effects of carbamoylcholine, suggesting that this densensitization involves inactivation of calcium entry.
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PMID:Involvement of calcium channels in short-term desensitization of muscarinic receptor-mediated cyclic GMP formation in mouse neuroblastoma cells. 625 69

Several calcium antagonists were screened for their effect on muscarinic acetylcholine receptor-mediated cyclic GMP formation in murine neuroblastoma cells (clone N1E-115). Mn2+, Ni2+, and verapamil rapidly antagonized the response noncompetitively, with the following order of potency: verapamil greater than Mn2+ greater than Ni2+. The effects of Mn2+ and Ni2+, but not those of verapamil, were largely reversed by increasing extracellular calcium concentration. Additional effects of these agents included displacement of [3H]quinuclidinyl benzilate binding by verapamil and elevation of cyclic GMP levels by Mn2+ and Ni2+ in the absence of agonists. These results are in support of the hypothesis that receptor-mediated cyclic GMP formation by these cells is dependent upon entry of calcium into the cell and demonstrate the complexity of the effects of calcium antagonists.
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PMID:Effect of some calcium antagonists on muscarinic receptor-mediated cyclic GMP formation. 629 67

The contribution of the changes in the diffuse double layer potential (surface potential) to the resting membrane potential of the mouse neuroblastoma (N-18 clone) was estimated with the use of fluorescent dyes and from the shift of the threshold potential of the Ca-spike. The membrane potential monitored by Rhodamine 6G was unchanged with variations of external K+ concentration [( K+]o) below about 10 mM, and changed linearly with log [K+]o above this concentration, similar to the changes observed with a microelectrode. This result indicates that the independence of the membrane potential of [K+]o at low [K+]o is not brought about by the artifacts caused by insertion of a microelectrode into the cell. The changes in the surface potential in response to various polyvalent cations (Mg2+, Ca2+, Mn2+, Cd2+ and La3+) were monitored by the fluorescence of ANS. The behavior of the surface potential thus observed was closely correlated with that of the membrane potential for the respective polyvalent cations. The surface potential changes in response to increase in [Ca2+]o from 1.8 to 100 mM and in [Mg2+]o from 0.8 to 100 mM were 88% and 85% in magnitude compared with the corresponding changes in the membrane potential, respectively. The effect of variation of [Ca2+]o on the threshold potential of the Ca-spike was compared with that of [Ca2+]o on the resting membrane potential. The magnitude of the surface potential change determined by the shift of the threshold potential was comparable to the magnitude of the membrane potential change. The results in the present study suggest that the surface potential change produced at the membrane surface of N-18 cells is detected as a transmembrane potential change without a large reduction in magnitude.
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PMID:Contribution of surface potential to resting potential in mouse neuroblastoma cells: estimation with fluorescent dyes and from shift of threshold potential for Ca-spike. 632 48

Ethylketocyclazocine (EKC) binds to two sites on NCB-20 neuroblastoma X Chinese hamster brain hybrid cells (KDH = 2 nM, Bmax = 21,000 sites/cell; KDL = 27 nM, Bmax = 140,000 sites/cell. The high-affinity site has been characterized as a delta opiate receptor. The low-affinity site is relatively benzomorphan-specific; opioid peptides, morphine, etorphine, and naloxone do not compete at it. Rank order of potency among benzomorphans is (+)-EKC greater than Mr 2267 greater than (+)-ketocyclazocine greater than (+)-SKF 10047 greater than bremazocine greater than cyclazocine. Among other drugs of interest that inhibit [3H]EKC binding are phencyclidine and its analogues, Ki values for which are 0.2-40 microM. Stereoselectivity is the reverse of other opioid receptors: (+)-EKC much much greater than (-)-EKC, Mr 2267 greater than Mr 2266, (+)-SKF 10047 greater than (-)-SKF 10047. The site is sensitive to trypsin, but not to N-ethylmaleimide. Binding is insensitive to nucleotides, slightly sensitive to physiological concentrations of sodium, magnesium, and manganese ions and to EDTA but not EGTA.
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PMID:[3H]ethylketocyclazocine binding to NCB-20 hybrid neurotumor cells. 633 80

The toxicological effects of manganese chloride on the redox state of thiols and on the lipid peroxidation in cultures of the neuroblastoma clone N1E 115 were studied. The cell cultures were exposed, after a stationary growth phase was attained, to manganese chloride (25-100 microM) for up to 9 days. The non-protein thiols decreased at the most 27% as compared to the controls. Significant effects were obtained at all manganese concentrations tested. The total thiol content was maximally reduced by 40%. This reduced thiol content was also reflected in a lowered activity of the thiolenzyme, glyceraldehyde-3-phosphate dehydrogenase in manganese exposed cells. In addition the lipid peroxide level in the cells was decreased during the manganese treatment.
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PMID:Changes in the redox state of neuroblastoma cells after manganese exposure. 663 53

The influence of divalent cations on glycosphingolipid metabolism was examined in the NB41A mouse neuroblastoma clonal cell line. HPLC methods were utilized to quantitate the effects on neutral glycolipids and monosialogangliosides. NB41A cells were shown to contain GM3, GM2, GM1, GD3, and GD1a by HPLC and TLC. The neutral glycosphingolipids consisted of glucosylceramide (GlcCer), lactosylceramide (LacCer), GalNAc (beta 1 leads to 4) Gal(beta 1 leads to 4)Glc(beta 1 leads to 1)Cer (GgOse3Cer), and GalNAc(beta 1 leads to 3)Gal(alpha 1 leads to 4) Gal(beta 1 leads to 4)Glc(beta 1 leads to 1)Cer (GbOse4Cer) according to their HPLC behavior. Cells grown in the presence of 1.85 mM-EGTA showed a two-to threefold increase in GM3 whereas other glycosphingolipids were only slightly affected. When cells were grown in the presence of 1.45 mM-EGTA plus 0.4 mM-EDTA a similar increase in GM3 was observed but this change was now accompanied by decreases in GM2, GM1, GgOse3Cer. The EGTA-EDTA effects were reversed when growth was in the presence of Ca2+ sufficient to bind all chelator. Mn2+ replacement reversed the chelator effects differentially; GM2 and GM1 levels were the most sensitive to increases in Mn2+ concentration; GgOse3Cer and GbOse4Cer were also sensitive, whereas GM3 was the least affected. These results suggest calcium serves an important regulatory role on GM3 levels and that manganese concentration may regulate the levels of galactosamine-containing glycolipids in mouse NB41A neuroblastoma cells.
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PMID:Effects of divalent cations on the glycolipids from cultured mouse neuroblastoma cells. 680 99


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