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)

Ethylcholine mustard aziridinium ion (AF64A, MEChMAz) has been proposed as a cholinergic neuron-specific neurotoxin. We report that in further studies on its mechanism of action incubation of the cholinergic neuroblastoma X glioma cell line, NG-108-15, with 100 microM AF64A resulted in a rapid decrease in cellular choline acetyltransferase (ChAT) activity which preceded cytotoxicity. Thus, a 60-85% decrease in ChAT activity was measured within 5 h of AF64A exposure, whereas cell lysis (measured as the release of the cytosolic enzyme lactate dehydrogenase into the medium) did not become apparent until 18 h of AF64A exposure. This led us to examine the effects of AF64A on partially purified ChAT. We report a concentration- and time-dependent inhibition of partially purified ChAT by AF64A that could not be reversed by dialysis but could be prevented by coincubation of the enzyme and AF64A with choline but not with acetyl-coenzyme A. We present kinetic evidence that choline and AF64A compete for the same site on the enzyme. In addition, thiosulfate, which inactivates the aziridinium ion, eliminated AF64A's capacity to inhibit the enzyme. AF64A also irreversibly inhibited partially purified choline kinase and acetylcholinesterase but not lactate dehydrogenase, alcohol dehydrogenase, carboxypeptidase A, or chymotrypsinogen, enzymes that do not use choline as a substrate or product. Thus, the data suggest that AF64A acts as an irreversible active site directed inhibitor of ChAT and possibly other enzymes recognizing choline.
 ...
PMID:AF64A: an active site directed irreversible inhibitor of choline acetyltransferase. 383 98

Four monoclonal antibodies were obtained to rat brain choline acetyltransferase (CAT). The enzyme was purified 95,000-fold from rat brain by precipitation with acetic acid at pH 4.5, fractionation with 40 to 60% (NH4)2SO4, CM-Sephadex chromatography, and affinity column chromatography on agarose-hexane-coenzyme A. The enzyme preparation was applied to the affinity column in the presence of 10 mM acetylcholine to increase the affinity of CAT for coenzyme A; the enzyme then was eluted with 10 mM acetyl coenzyme A. Fusion of P3X63 Ag8 myeloma cells with spleen cells isolated from a BALB/c mouse that had been immunized with affinity-purified CAT with a specific activity of 29.4 mumol of ACh synthesized/min/mg of protein resulted in the isolation of four hybridomas synthesizing antibodies to CAT that inhibit the activity of the enzyme. Anti-CAT 1 or 2 inhibits CAT activity 100%. At the highest antibody concentration tested, anti-CAT 3 inhibited acetylcholine synthesis 80%. Hybridoma antibody-dependent inhibition of CAT activity was reversed by dissociation of immune complexes via dilution, demonstrating that antibody binding does not irreversibly alter the structure of the enzyme. When bound to [rabbit anti-mouse IgG . protein A Staphylococcus aureus] complexes, anti-CAT 1, 3, and 4 each were effective reagents for the precipitation of CAT activity from solution. Thirty-one to 53% of the precipitated enzyme was recovered following the dissociation of immune complexes. Anti-CAT 1, 2, and 3 inhibit CAT from 18-day chick embryo brain, NS20-Y mouse neuroblastoma cells, and rat brain.
 ...
PMID:Inhibition of choline acetyltransferase by monoclonal antibodies. 388 Aug 11

N1E-115 neuroblastoma cells were grown in the absence or presence of atropine (1 microM) for 9 days. After 9 days membranes were prepared from control and atropine-treated cells. They were stored frozen until some markers of muscarinic cholinergic function were measured. Atropine treatment increased the number of muscarinic receptors from 100 +/- 10 fmol/mg protein to 145 +/- 20 fmol/mg protein, decreased the cholinesterase activity from 3.5 +/- 2.0 U/mg protein to 1.0 +/- 0.5 U/mg protein and increased the choline acetyltransferase activity from 0.25 +/- 0.13 pmol [3H]acetylcholine synthesized/min X mg protein to 1.80 +/- 0.59 pmol [3H]acetylcholine synthesized/min X mg protein. It is suggested that all these changes are correlates of muscarinic receptor supersensitivity.
 ...
PMID:Long time treatment of N1E-115 neuroblastoma cells with atropine induces changes in markers of muscarinic cholinergic function. 396 Mar 99

Mouse neuroblastoma cells (clone neuro-2A) in the undifferentiated and "differentiated" form were compared by light and electron microscopy. "Cytodifferentiation" was induced in monolayer cultures by the addition of dibutyryl-cyclic AMP. The pattern of concanavalin A binding sites was studied after coupling with horseradish peroxidase. The following major differences were observed. The differentiated cells are characterized by numerous and long neurites, aggregation of ribosomes into polysomes, an extensive network of neurofilaments and microtubules, many dense-core neurosecretory-like vesicles, a discontinuous pattern of concanavalin A binding sites on the plasma membrane, and an increase of the specific activities of acetylcholinesterase, choline acetylase and tyrosine hydroxylase. In contrast, the undifferentiated cells grown in suspension culture lack neurites, contain dispersed ribosomes, infrequent neurofilaments and microtubules and dense-core neurosecretory-like vesicles, and exhibit a continuous pattern of concanavalin A binding sites. In addition, the specific activities of the above mentioned enzymes are significantly lower.
 ...
PMID:The undifferentiated and extended forms of C1300 murine neuroblastoma. An ultrastructural study and detection of concanavalin A binding sites on the plasma membrane. 415 21

Neuroblastoma clones were examined for choline acetyltransferase (EC 2.3.1.6), tyrosine hydroxylase (EC 1.14.3.a), acetylcholinesterase (EC 3.1.1.7), and also for neurite formation. One clone does not form axons or dendrites. Three types of clones were found with respect to neurotransmitter synthesis: cholinergic, adrenergic, and clones that do not synthesize acetylcholine or catechols. All clones contain acetylcholinesterase. These results show that genes determining neurotransmitter species can be expressed in dividing cells, that the parental programs of gene expression are inherited, and that dividing cells can be programmed with respect to their ability to communicate with other cells.
 ...
PMID:Neurotransmitter synthesis by neuroblastoma clones (neuroblast differentiation-cell culture-choline acetyltransferase-acetylcholinesterase-tyrosine hydroxylase-axons-dendrites). 440 Feb 94

The specific activity of mouse neuroblastoma choline-O-acetyltransferase (EC 2.3.1.6.) increased 5.7-fold when the rate of cell division was restricted (as compared to cells kept rapidly dividing for 9 days); the specific activity of mouse neuroblastoma thymidylate synthetase increased 2.4-fold when nondividing cells again entered the logarithmic phase of cell growth. The highest specific activities for choline-O-acetyltransferase and lowest specific activities for thymidylate synthetase were obtained from cultures where cell division was restricted; the opposite result was observed when the cells were growing rapidly. Thus, the regulation of these two enzymes is out of phase with respect to each other and is dependent on the rate of cell division. The inverse relationship for the regulation of these two enzymes is discussed in relation to the needs of mitotic versus differentiated neuroblastoma cells.
 ...
PMID:Regulation of the synthesis of choline-O-acetyltransferase and thymidylate synthetase in mouse neuroblastoma in cell culture. 528 32

A differential assay for the determination of choline acetyltransferase activity in neuroblastoma is described, and the importance of using the differential assay is discussed. In addition, changes in cholinergic-adrenergic activity of cloned adrenergic neuroblastoma cells after serial transplantations are reported. The changes of the cholinergic activity could not be detected precisely without the use of the differential assay.
 ...
PMID:Differential assay of choline acetyltransferase activity in human neuroblastomas and cloned adrenergic neuroblastoma of mouse. 612 16

Two neurotransmitter-synthesizing enzymes, tyrosine hydroxylase (TH) and choline acetyltransferase (CAT), were assayed in neuroblastoma tissues from 24 children, in human neuroblastoma tissues serially transplanted in nude mice, and in human neuroblastoma cells in culture. Among tissues from 24 children, five showed an adrenergic pattern with significant TH activity alone, seven showed a cholinergic pattern with significant CAT activity alone, and the remaining 12 specimens showed a "both-active" pattern with both TH and CAT activity. Enzymatic activities were maintained through many serial passages in vitro and in nude mice. All four specimens from children under one year of age exhibited the adrenergic pattern. In general, enzymatic activity was not correlated with degree of differentiation histologically. Among four cases of paravertebral dumb-bell type in this series, two were cholinergic, one was adrenergic, and the last was both-active. These results suggest that dumb-bell type tumors may arise from either sympathetic ganglia or dorsal root ganglia. This study supports the concept that neuroblastomas are a composite of adrenergic and cholinergic cells. Significant changes in the relative proportions of these two cell types were observed with time, and after extensive therapy. Different metastatic sites often exhibited important differences in enzymatic activity. These results help to account for clinical discrepancies between urinary VMA levels and tumor growth. Assays for TH and CAT can be useful for confirming a diagnosis of neuroblastoma, and have important potential for helping to clarify the natural history of neuroblastoma.
 ...
PMID:Tyrosine hydroxylase and choline acetyltransferase activity in human neuroblastoma. Correlations with clinical features. 613 77

A new human cell line, TR14 , has been established in tissue culture from biopsy material of a primary neuroblastoma tumor. Most TR14 cells have short processes and grow mainly in clumps adhering to cells attached to the substratum. TR14 cells form colonies in soft agar demonstrating anchorage independence of growth and produce tumors in nude mice with histologies similar to that of the patient's tumor. The neurotransmitter-synthesizing activity of these cells is predominantly cholinergic with only a minor adrenergic component, since the activity of choline acetyltransferase is about 20-fold greater than that of tyrosine hydroxylase. Treatment with N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate induces TR14 neuroblastoma cells to extend fine, long processes or neurites. This morphological change is accompanied by elevated numbers of cytoplasmic dense-core vesicles observed by electron microscopy and an increase in the activities of neurotransmitter-synthesizing enzymes. Differentiation therefore occurs at the levels of cellular morphology, ultrastructure, and biochemistry. Prostaglandin E1 and cholera toxin can also induce differentiation, but a range of other agents including dimethyl sulfoxide, nerve growth factor, butyrate, corticosteroids, and 5-bromodeoxyuridine is ineffective. The concomitant induction of both morphological and biochemical differentiation therefore appears to be exclusively a cyclic adenosine 3':5'-monophosphate-mediated event in this cell line.
 ...
PMID:Characteristics of a new human neuroblastoma cell line which differentiates in response to cyclic adenosine 3':5'-monophosphate. 614 83

A new hybrid cell line, designated NG115-401, produced a significant amount of immunoreactive (IR) substance P-like material. The production was measured by radioimmunoassay using specific antisera raised to substance P. The production rate was dependent upon cell growth, and maximum production occurred at the same stage (late logarithmic stage) as the time of appearance of choline acetyltransferase activity, one of the characteristic neuronal properties of the cells. On the other hand, no IR-substance P was found in hybrid cells other than NG115-401, i.e. NG115-301 and NG115-303 cells, which were derived from the same parent mouse neuroblastoma N115TG-2 cells. Furthermore, in an attempt to survey IR-substance P production in several clonal cells, consisting of some mouse neuroblastoma cells and a rat glioma cell, and several of their hybrid cells, we could find no cell line producing a significant amount of IR-substance P except for NG115-401 hybrid cells. The cellular production of IR-substance P in NG115-401 hybrid cells was also confirmed by detecting the material in all 14 subpopulations of this hybrid cells. Partial characterization of IR-substance P-like material produced by NG115-401 hybrid cells was carried out by its application to gel-filtration column chromatography. Only high molecular weight material (approximately 26,000) appeared in the column eluates.
 ...
PMID:A mouse neuroblastoma x rat glioma hybrid cell produces immunoreactive substance P-like material. 616 18


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