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)

Alphaviruses replicate in a wide variety of cells in vitro. The prototype alphavirus, Sindbis virus, causes an age-dependent encephalitis in mice and serves as an important model system for the study of alphavirus neurovirulence. To begin to understand the role of cellular virus receptors in the pathogenesis of Sindbis virus infection, we developed an anti-idiotypic antibody made in rabbits against a neutralizing monoclonal antibody specific for the E2 surface glycoprotein. The anti-idiotypic antibody (anti-Id 209) bound to N18 mouse neuroblastoma cells and inhibited adsorption of 35S-labeled virus by 50%. Binding of anti-Id 209 was inhibited by pretreatment of N18 cells with various proteases but not with neuraminidase or phospholipase, while virus binding was inhibited by pretreatment with phospholipase as well as protease. Anti-Id 209 precipitated proteins of 110 and 74 kDa from N18 cells intrinsically labeled with [35S]methionine. N18 cells grow with two phenotypes in culture, and immunoprecipitation of 125I-surface-labeled cells showed that the 74-kDa protein was present on loosely adherent cells growing in aggregates, while the 110-kDa protein was present in smaller amounts on firmly adherent cells growing as a monolayer. Analysis of brain cells from newborn mice by flow cytometry showed that all cells expressed the receptor protein at birth, but by 4 days after birth half of the cells had ceased receptor expression. A survey of other cell lines showed the protein to be present on murine fibroblastic and other rodent neuroblastoma cell lines but rarely on human neural or nonneural cell lines. These studies suggest that one of the receptors for Sindbis virus on mouse neural cells is a protein that is regulated during development of the nervous system. Developmental down-regulation of receptor protein expression may contribute to the age-dependent nature of susceptibility of mice to fatal alphavirus encephalitis.
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PMID:Identification of a putative alphavirus receptor on mouse neural cells. 165 82

A common feature of scrapie and related transmissible spongiform encephalopathies is the accumulation of an abnormal protease-resistant form of PrP which may be the major component of the infectious agent. While it is known that both the normal (protease-sensitive) PrP and protease-resistant PrP are encoded by the same endogenous gene, the nature of the disease-associated modification of PrP is not understood. To study the cellular events leading to the formation of protease-resistant PrP, we have compared its biosynthesis to that of its normal isoform in scrapie-infected mouse neuroblastoma cells. In pulse-chase labeling experiments, the protease-resistant PrP was synthesized and degraded much more slowly than the normal PrP, suggesting that protease-resistant PrP is made from a protease-sensitive precursor. More significantly, we found that the precursor of protease-resistant PrP was eliminated from intact cells by treatments with phosphatidylinositol-specific phospholipase C and trypsin. This demonstrated that, unlike the protease-resistant PrP itself, the precursor is phospholipase- and protease-sensitive and at least transiently found on the cell surface. By these criteria, the precursor of protease-resistant PrP is indistinguishable from the normal PrP isoform. These results indicate that the conversion of PrP to the protease- and phospholipase-resistant state is a post-translational event that occurs after the precursor reaches the cell surface.
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PMID:The scrapie-associated form of PrP is made from a cell surface precursor that is both protease- and phospholipase-sensitive. 168 Aug 59

In addition to whatever function PrP may have normally, its involvement in scrapie-like neurodegenerative diseases has become clearer in recent years. In vitro studies have made important contributions to the understanding of normal PrP biosynthesis and turnover and how they can be influenced by scrapie infection. Cell-free transcription and translation experiments have indicated that PrP gene translation products are capable of assuming two different topologies, one spanning microsomal membranes and the other completely translocated into the microsomal lumen (Hay et al. 1987a, b). A novel stop transfer signal in the polypeptide is critical to the formation of the transmembrane topology (Yost et al. 1990). Expression of recombinant PrP genes has been accomplished in mouse (Caughey et al. 1988b), monkey (Scott et al. 1988), frog (Hay et al. 1987a), and insect (Scott et al. 1988) tissue culture cells. PrP products encoded by PrP cDNAs cloned from scrapie-infected brain tissues are not infectious and do not have the protease-resistance characteristic of the scrapie-associated form of PrP isolated from diseased tissue (Caughey et al. 1988b; Scott et al. 1988). Studies of PrP encoded by the endogenous gene of mouse neuroblastoma cells have identified the precursors (Caughey et al. 1989) and products (Race et al. 1988; Caughey et al. 1989) of normal PrP biosynthesis and shown that most of the PrP of normal cells is linked to the cell surface by phosphatidylinositol (Stahl et al. 1987; Caughey et al. 1989, 1990; Borchelt et al. 1990). In scrapie-infected clones, and additional pool of PrP is present which, unlike the normal PrP, aggregates (B. Caughey, unpublished observations) and is partially protease resistant (Butler et al. 1988; Caughey et al. 1990; Borchelt et al. 1990; Stahl et al. 1990). This scrapie-associated pool of PrP differs from the normal PrP in that it is primarily intracellular (Caughey et al. 1990; Borchelt et al. 1990; Taraboulos et al. 1990) and resistant to removal from cells by phospholipase or protease (Caughey et al. 1990; Borchelt et al. 1990; Stahl et al. 1990) treatments. Kinetic studies have shown that while PrP-sen is synthesized and degraded relatively rapidly (Caughey et al. Borchelt et al. 1990), PrP-res is synthesized slowly and has a very long half-life (Borchelt et al. 1990). Further studies with the scrapie-infected mouse neuroblastoma cells should lead toward the elucidation of the molecular details of the scrapie-associated modification of PrP and whether the modification is directly related to scrapie agent replication.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In vitro expression and biosynthesis of prion protein. 168 86

This study characterizes free fatty acid release in a neuroblastoma cell line (Neuro-2A), a potential model system for the study of factors that control phospholipase A2 in neurons. Two compounds, bicuculline (an antagonist at gamma-aminobutyric acid receptors), and A23187 (a Ca2+ ionophore), were examined. The release of endogenous fatty acids and the turnover of radiolabeled arachidonic and docosahexaenoic acids were measured. The cells actively incorporated radiolabeled fatty acids into various glycerolipid pools. Both endogenous fatty acids and radiolabeled fatty acids were released from glycerolipids in a time-dependent manner. Phosphatidylcholine was a major source of released fatty acids. Release of free fatty acids was markedly stimulated by both bicuculline and A23187. We conclude that the Neuro-2A cells contain phospholipase activity that is sensitive to Ca2+ ionophore and bicuculline, and may provide a good system for further studies on the regulation of phospholipase A2 in neurons.
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PMID:Bicuculline induces free fatty acid release from phospholipids in neuro-2A cells in culture. 183 5

Previous studies have indicated that scrapie infection results in the accumulation of a proteinase K-resistant form of an endogenous brain protein generally referred to as prion protein (PrP). The molecular nature of the scrapie-associated modification of PrP accounting for proteinase K resistance is not known. As an approach to understanding the cellular events associated with the PrP modification in brain tissue, we sought to identify proteinase K-resistant PrP (PrP-res) in scrapie-infected neuroblastoma cells in vitro and to compare properties of PrP-res with those of its normal proteinase K-sensitive homolog, PrP-sen. PrP-res was detected by immunoblot in scrapie-infected but not uninfected neuroblastoma clones. Densitometry of immunoblots indicated that there was two- to threefold more PrP-res than PrP-sen in one infected clone. Metabolic labeling and membrane immunofluorescence experiments indicated that PrP-sen was located on the cell surface and could be removed from intact cells by phosphatidylinositol-specific phospholipase C and proteases. In contrast, PrP-res was not removed after reaction with these enzymes. Thus, either the scrapie-associated PrP-res was not on the cell surface or it was there in a form that is resistant to these hydrolytic enzymes. Attempts to detect intracellular PrP-res by immunofluorescent staining of fixed and permeabilized cells revealed that PrP was present in discrete perinuclear Golgi-like structures. However, the staining pattern was similar in both scrapie-infected and uninfected clones, and thus the intracellular staining may have represented only PrP-sen. Analysis of scrapie infectivity in cells treated with extracellular phospholipase, proteinase K, and trypsin indicated that, like PrP-res, the scrapie agent was not removed from the infected cells by any of these enzymes.
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PMID:Normal and scrapie-associated forms of prion protein differ in their sensitivities to phospholipase and proteases in intact neuroblastoma cells. 196 4

Numerous studies have indicated that a modified proteinase K-resistant form of an endogenous brain protein, prion protein (PrP), is associated with scrapie infection in animals. This scrapie-associated PrP modification appears to occur posttranslationally in brain, but its molecular nature is not known. To learn about the normal PrP biosynthesis and whether it is altered by scrapie infection in vitro, we did metabolic labeling experiments with uninfected and scrapie-infected mouse neuroblastoma tissue culture cells. Pulse-chase labeling experiments indicated that, in both cell types, two major PrP precursors of 28 and 33 kilodaltons (kDa) were processed to mature 30- and 35- to 41-kDa forms. Endoglycosidase H, tunicamycin, and phospholipase treatments revealed that the 28- and 33-kDa precursors resulted from the addition of high-mannose glycans to a 25-kDa polypeptide containing a phosphatidylinositol moiety and that maturation of the precursors involved the conversion of the high-mannose glycans to hybrid or complex glycans. Treatments of the live cells with trypsin and phosphatidylinositol-specific phospholipase C indicated that the mature PrP species were expressed solely on the cell surface, where they were anchored by covalent linkage to phosphatidylinositol. Once on the cell surface, the major PrP forms had half-lives of 3 to 6 h. No differences in PrP biosynthesis were observed between the scrapie-infected versus uninfected neuroblastoma cells.
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PMID:Prion protein biosynthesis in scrapie-infected and uninfected neuroblastoma cells. 256 14

Chronic treatment of neuroblastoma X glioma NG108-15 hybrid cells with opiate agonist resulted in loss of the acute opiate inhibition of adenylate cyclase activity with a concomitant increase in the enzymatic activity observable on addition of the antagonist naloxone. The role of membrane lipids in the cellular expression of these chronic opiate effects was investigated by the hydrolysis of phospholipids with various lipases. Treatment with phospholipase C from Clostridium welchii produced an enzyme concentration-dependent decrease of prostaglandin E1-stimulated adenylate cyclase activity in control or etorphine-treated (1 microM for 4 h) hybrid cells. In addition, incubation of hybrid cells with phospholipase C concentrations of greater than or equal to 0.5 U/ml completely abolished the compensatory increase in adenylate cyclase activity after chronic opiate treatment. This attenuation of the increase in adenylate cyclase activity by phospholipase C could be prevented by inclusion of phosphatidylcholine but not of phosphatidic acid during the enzymatic incubations. The specificity of the phospholipids involved in expression of the chronic opiate effect could be demonstrated further by the absence of effect exhibited by phospholipase C from Bacillus cereus and phospholipase D. Hydrolysis of the acyl side chains of phospholipids with phospholipase A2 did not alter the chronic opiate effect after removal of lysophosphatides with bovine serum albumin. Because the guanylylimidodiphosphate- and NaF-sensitive adenylate cyclase activities were not affected by these phospholipase treatments, the expression of the compensatory increase in adenylate cyclase activity is mediated via an increase in the coupling between hormonal receptor and adenylate cyclase with the participation of the polar head groups of the phospholipids and not the hydrophobic side chains.
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PMID:Effect of phospholipases on chronic opiate action in neuroblastoma X glioma NG108-15 hybrid cells. 301 58

The mechanism of action of the alkylating agent bis-(2-chloroethyl)sulfide (sulfur mustard, SM) was studied using the in vitro mouse neuroblastoma-rat glioma hybrid NG108-15 clonal cell line model. Following 0.3 mM SM exposure, cell viability remained high (> 80% of untreated control) up to 9 hr and then declined steadily to about 40% of control after 20-24 hr. During the early period of SM exposure, when there was no significant cell viability loss, the following effects were observed. The cellular glutathione level decreased 20% after 1 hr and 34% after 6 hr. Between 2 and 6 hr, there was a time-dependent increase (about 10 to 30%) in intracellular free calcium (Ca2+), which was localized to the limiting membrane of swollen endoplasmic reticula and mitochondria, to euchromatin areas of the nucleus, and to areas of the cytosol and plasma membrane. Moreover, there was also a time-dependent increase in the release of isotopically labeled arachidonic acid ([3H]AA) from cellular membranes. Increase in [3H]AA release was 28% at 3 hr and about 60-80% between 6 and 9 hr. This increase in [3H]AA release was inhibited by quinacrine (20 microM), which is a phospholipase (PLA2) inhibitor. At 16 hr after SM exposure, there was a large increase (about 200% of control) in [3H]AA release, which was coincident with a 50% loss of cell viability. These results suggest a Ca(2+)-mediated toxic mechanism of SM via PLA2 activation and arachidonate release.
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PMID:Sulfur mustard-induced increase in intracellular free calcium level and arachidonic acid release from cell membrane. 787 77

A phospholipase-C-linked nucleotide receptor, sensitive to both uridine and adenosine triphosphate (UTP and ATP) has been cloned from NG108-15 neuroblastoma x glioma hybrid cells. We have tested whether activation of this receptor could inhibit the voltage-dependent K+ current [IK(M) or "M-current"] in NG108-15 cells recorded using whole-cell patch-clamp methods. Both UTP and ATP inhibited IK(M) by 44% and 42%, respectively, at 100 microM. Mean IC50 values were: UTP, 0.77 +/- 0.27 microM; ATP, 1.81 +/- 0.82 microM. The order of nucleotide and nucleoside activity at 100 microM was: UTP = ATP > ATP [gamma S] = ITP > 2-MeSATP > ADP = GTP >> AMP-CPP, adenosine, where ATP[gamma S] is adenosine 5'-O-(3-thiotriphosphate), ITP is inosine 5'-triphosphate, 2-MeSATP is 2-methylthio ATP and AMP-CPP is alpha, beta methylene ATP. This rank order accords with their activities at the cloned P2U receptor. Effects were not inhibited by suramin (up to 500 microM) or by pre-incubation for 12 h in 500 ng.ml-1 Pertussis toxin. Inhibition of IK(M) was frequently preceded by a transient outward current, probably a Ca(2+)-activated K+ current, responding to Ca2+ mobilization. No effect on the delayed rectifier K+ current was observed. These observations match those expected from stimulating other phospholipase-C-linked receptors in NG108-15 cells.
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PMID:Activation of nucleotide receptors inhibits M-type K current [IK(M)] in neuroblastoma x glioma hybrid cells. 789 8

Concerning molecular and cellular mechanisms of aluminum toxicity, recent studies support the hypothesis that interactions of aluminum ions with elements of signal transduction pathways are apparently primary events in cells. In the case of the phosphoinositide-associated signalling pathway of neuroblastoma cells, guanine nucleotide-binding proteins (G proteins) and a phosphatidylinositol-4,5-diphosphate (PIP2)-specific phospholipase C are probable interaction sites for inhibitory actions of aluminum ions. Following interiorization of aluminum by the cell, metal interactions decrease the accumulation of inositol phosphates, especially that of inositol-1,4,5-triphosphate (IP3), concomitant with derangements of intracellular Ca2+ homeostasis. In the presence of high concentrations of Ca2+, formation of IP3 is also diminished in aluminum-pretreated cells, presumably involving a process not requiring Mg(2+)-dependent G proteins. At higher aluminum doses, metal-induced changes in the lipid milieu of the membrane-bound phospholipase may play a role. These types of primary interactions of aluminum ions with elements of cellular communication channels are probably crucial in the manifestation of the multifacetted aluminum toxicity syndrome. If present as a phosphate-like fluoro-aluminate, a stimulatory role of aluminum ions is displayed in G protein-coupled transmembrane signalling.
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PMID:Aluminum interaction with phosphoinositide-associated signal transduction. 816


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