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Query: UMLS:C0031511 (pheochromocytoma)
 14,622 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

High-affinity (Kd approximately equal to 10 nM) binding sites for nicotine and acetylcholine (ACh) have recently been identified in vertebrate brain. It has been suggested that these sites are desensitized ganglionic (C6) nicotinic acetylcholine receptors (nAChRs). We have tested the pheochromocytoma cell line PC12, which is known to contain well-expressed C6 nAChRs, to determine if these nAChRs are associated with high-affinity [3H]ACh-binding sites. We found that the high-affinity nicotinic [3H]ACh-binding site is absent in PC12 cells. We also found that the concentration of nicotine or ACh necessary to desensitize carbamylcholine-stimulated Na+ flux was at least two orders of magnitude greater than the concentrations used in binding experiments. We conclude that high-affinity nicotinic binding sites are not equivalent to C6 ganglionic receptors.
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PMID:Ganglionic nAChRs and high-affinity nicotinic binding sites are not equivalent. 374 77

PC12 pheochromocytoma cells take up 3,4-dihydroxyphenylethylamine (dopamine) and norepinephrine by a Na+-dependent, cocaine-sensitive system. The kinetics suggest that the same transporter functions for both substrates. Xylamine, a nitrogen mustard that blocks catecholamine uptake into neurons, irreversibly inhibited norepinephrine uptake into PC12 (IC50 = 15 microM). Pretreatment with 10 microM xylamine did not inhibit norepinephrine transport if 10 microM cocaine or 100 microM norepinephrine was also present during the pretreatment period or if Na+ was absent. These results indicate that xylamine must interact with the norepinephrine transporter to inhibit norepinephrine uptake. PC12 accumulated [3H]xylamine; this uptake had Na+-dependent and Na+-independent components. The Na+-dependent uptake was saturable (Km = 13 microM), and it was inhibited by cocaine (IC50 = 0.6 microM), desipramine (IC50 less than 1 nM), and norepinephrine (IC50 = 1 microM). Several proteins became prominently labeled when intact PC12 cells were incubated with [3H]xylamine; these proteins were enriched in a plasma membrane fraction and have molecular weights of 17,000, 24,000, 31,000, 33,000, 41,000, 42,000, 52,000, and 80,000. Other proteins were labeled less prominently. The labeling of all proteins was markedly decreased when the incubation with [3H]xylamine occurred in the presence of cocaine, desipramine, gramicidin D, or in a Na+-free buffer. These results indicate that xylamine must be transported into the cells for covalent binding to proteins to occur. [3H]Xylamine labeled essentially the same proteins when incubated with cell homogenates, but competition experiments with bretylium, desipramine, and cocaine failed to reveal which of the [3H]xylamine-labeled proteins is associated with the norepinephrine transporter.
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PMID:Characterization of xylamine binding to proteins of PC12 pheochromocytoma cells. 374 2

Monensin, a monovalent cation ionophore, induced profound release of radiolabeled materials from clonal rat pheochromocytoma cells (PC12h) preloaded with [3H]norepinephrine (NE). The release was suppressed in the absence of external Na+, but was not affected at all in the absence of external Ca2+. Cytosolic free Ca2+ concentration ([Ca2+]i), that was monitored by means of a fluorescent Ca2+ indicator, Quin 2, was temporarily increased upon a depolarizing stimulus of high-K+, which induced the Ca2+-dependent release of [3H]NE from PC12h cells. On the other hand, monensin induced only a slight increase in [Ca2+]i. The radiolabeled materials released by high-K+ treatment were mainly [3H]NE, whereas those by monensin were mainly the metabolites of [3H]NE. Pargyline, a monoamine oxidase inhibitor, suppressed both the degradation of [3H]NE stored in PC12h cells and the monensin-induced release of radiolabeled compounds from them. Monensin decreased the content of [3H]NE in storage granules of pargyline-treated cells. Thus, it is likely that monensin expels NE from the storage vesicles to cytosol and then its metabolites by monoamine oxidase are released in a non-exocytotic manner.
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PMID:The mechanism of calcium-independent catecholamine depleting action of monensin from clonal rat pheochromocytoma cells. 375 21

Bovine chromaffin granules from adrenal medulla contain three acidic secretory proteins: chromogranins A, B, and C. For isolation of these proteins, methods based mainly on high performance liquid chromatography were developed. After removal of contaminating glycoproteins by lectin affinity chromatography, chromogranins were separated by high performance anion-exchange, gel-filtration, and reverse phase liquid chromatography. As a final purification step sodium dodecyl sulfate-gel electrophoresis was performed. Amino acid analysis of isolated bovine chromogranins revealed a similar composition of all three proteins, with glutamic acid being the most prominent amino acid. The methods developed for bovine proteins also proved suitable for isolating rat chromogranins A and B from a transplantable pheochromocytoma. Chromogranin C was not present in sufficient amounts to be isolated from this tissue. The chromogranins purified by these methods were used to raise specific antibodies in rabbits. The use of purified chromogranins together with specific antisera may be valuable in understanding the still undiscovered function of these proteins.
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PMID:Isolation and characterization of chromogranins A, B, and C from bovine chromaffin granules and a rat pheochromocytoma. 379 5

Rat pheochromocytoma (PC12) cells grown in the presence or absence of nerve growth factor (NGF) were pulse-labeled with [35S]methionine or 32Pi, and neurofilament subunits were recovered by immunoprecipitation from cellular extracts. The neurofilament subunits, with apparent molecular masses on sodium dodecyl sulfate-polyacrylamide gels of 68 kDa (light, L), 145 kDa (medium, M), and 200 kDa (heavy, H), were all found to be expressed in PC12 cells grown in the absence and presence of NGF. H was expressed at very low levels and in a form that migrated more rapidly on sodium dodecyl sulfate gels than H from rat brain. M was synthesized as a more rapidly migrating precursor that underwent modification within 3 h after labeling to a slower migrating form that co-migrated with M from rat brain. Analysis of the different M species by two-dimensional gel electrophoresis indicated that they also had different isoelectric points consistent with differences in phosphate content. NGF treatment resulted in increased L synthesis and, to a lesser degree, M synthesis, but had no effect on H synthesis. NGF also increased the stability of the modified form of M. All three subunits were 32P-labeled, and NGF increased the incorporation of 32P into M and H. Neurofilament subunits were also immunoprecipitated from a soluble fraction of [35S]methionine-labeled PC12 cells. This soluble pool of subunits differed from the cytoskeleton-associated pool in the relative proportions of individual subunits, M being the predominant form in the former and L in the latter.
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PMID:Nerve growth factor enhances the synthesis, phosphorylation, and metabolic stability of neurofilament proteins in PC12 cells. 380 99

PC12 pheochromocytoma cells cease dividing and show increased cell-cell and cell-substratum adhesion in response to treatment with sodium butyrate. These changes are accompanied by the rapid appearance of neuron-specific enolase, an APUD cell marker. However, neurofilament proteins, markers for neuronal differentiation, are not induced. These results suggest that sodium butyrate induces differentiation in the PC12 cell line, perhaps along the chromaffin cell pathway.
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PMID:Differentiation of PC12 pheochromocytoma cells by sodium butyrate. 381 13

The polypeptide growth factors, nerve growth factor, epidermal growth factor, and platelet-derived growth factor, as well as insulin do not induce ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) unless a minimal concentration of an ornithine decarboxylase-inducing amino acid, such as asparagine, is present in the medium. The effects of the growth factors were studied in appropriately responsive cell lines: pheochromocytoma (PC12) cells for nerve and epidermal growth factors, fibroblasts (NIH 3T3) for platelet-derived growth factor, and fibroblasts and hepatoma (KRC-7) cells for insulin. The nonmetabolizable amino acid analog alpha-aminoisobutyric acid can replace asparagine, indicating that the covalent modification of the inducing amino acid is not necessary for the induction of ornithine decarboxylase by these growth factors. For the same intracellular concentration of the inducing amino acid, the presence of the growth factors induces higher levels of ornithine decarboxylase. The evidence indicates that these growth factors do not induce ornithine decarboxylase by raising the intracellular concentration of amino acids but rather act synergistically with the inducing amino acid. Evidence is provided that the induction of polyamine-dependent growth by these growth factors is mediated by amino acids. The relationship of these results to the A and N amino acid transport systems and to the Na+ influxes in relation to growth is discussed.
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PMID:Induction of ornithine decarboxylase activity by insulin and growth factors is mediated by amino acids. 389 32

The response to heat shock at 47 degrees C was examined in the cyanobacterium (blue-green alga) Synechococcus sp. strain PCC 6301. On heat shock, the growth of the cells decreased and they preferentially synthesized a limited number of polypeptides. The rate of synthesis of these proteins increased markedly in the early period of temperature shift up and gradually decreased afterwards. Among the proteins greatly affected by temperature shift up were those with apparent molecular weights of 91,000 (91K), 79K, 78K, 74K, 65K, 64K, 61K, 49K, 45K, 24K, 22K, 18K, 16K, 14K, 12K, and 11.4K, based on their mobilities in sodium dodecyl sulfate-polyacrylamide gels. From these initial studies on Synechococcus sp. strain PCC 6301 we conclude that in cyanobacteria a heat shock response similar to that known to occur in other eucaryotes and procaryotes might exist.
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PMID:Effect of heat shock on protein synthesis in the cyanobacterium Synechococcus sp. strain PCC 6301. 391 83

The effects of glioma-conditioned medium (GCM) and factors contained in GCM on the neurochemical differentiation of the PC12 clone of rat pheochromocytoma cells were investigated. The results obtained are as follows. The accumulation of choline into PC12 cells proceeded through two uptake systems with high (Km = 3.20 microM) and low (Km = 65.2 muM) affinities as revealed by least-squares iterative fitting of a substrate-velocity curve to the data. Culturing of PC12 cells in the presence of GCM led to a 5-fold increase in the Vmax value of the high-affinity uptake system without affecting the Km of the high-affinity uptake system. Both Km and Vmax of the low-affinity uptake system were unaffected by the GCM treatment. The high-affinity choline uptake system in both GCM-treated and untreated PC12 cells was devoid of Na+ dependency and showed low sensitivity to hemicholinium-3. The ratio of [3H]acetylcholine converted from [3H]choline taken up by PC12 cells at 1 muM choline for 1 h was two-fold higher than that by untreated cells. PC12 possess a high-affinity norepinephrine uptake system. Culturing of PC12 cells in the presence of GCM led to a decrease in the rate of uptake of 3 muM norepinephrine to 43% of that in control cells. The 40-K and 10-K fractions isolated by gel filtration of GCM had both abilities to enhance the high-affinity choline uptake system and to suppress the high-affinity norepinephrine uptake system. From these observations it was concluded that GCM contains factors which induce the cholinergic neuronal differentiation of PC12 cells.
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PMID:Cholinergic differentiation of clonal rat pheochromocytoma cells (PC12) induced by factors contained in glioma-conditioned medium: enhancement of high-affinity choline uptake system and reduction of norepinephrine uptake system. 394 5

The biosynthesis and secretion of dopamine beta-hydroxylase were investigated by radiolabeling rat pheochromocytoma (PC12) cells in culture. Intracellular dopamine beta-hydroxylase from a crude chromaffin vesicle fraction and secreted dopamine beta-hydroxylase from culture medium were immunoprecipitated using antiserum made against purified bovine soluble dopamine beta-hydroxylase. Analysis of the immunoprecipitated enzyme on sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that: 1) the membrane-bound form of the hydroxylase from crude secretory vesicle membrane extracts contained two nonidentical subunits in approximately stoichiometric amounts (Mr = 77,000 and 73,000); 2) the soluble hydroxylase from the lysate of these secretory vesicles was composed predominantly of a single subunit (Mr = 73,000); and 3) the hydroxylase secreted into the medium under resting conditions was also composed of a single subunit (approximate Mr = 73,000). All subunits of the multiple forms of hydroxylase were glycoproteins. Under resting conditions, the rate of secretion of hydroxylase was approximately 6% of total cellular enzyme/15 min. The secreted form of the hydroxylase incorporated [35S]sulfate, whereas no significant [35S]sulfate was incorporated into the cellular forms of enzyme. We propose that in addition to the dopamine beta-hydroxylase which is found in catecholamine storage vesicles and released during stimulus-coupled exocytosis, PC12 cells also have a constitutive secretory pathway for dopamine beta-hydroxylase and that the enzyme released by this second pathway is sulfated.
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PMID:Sulfation and constitutive secretion of dopamine beta-hydroxylase from rat pheochromocytoma (PC12) cells. 398 Apr 83


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