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)

Calcineurin is a calcium/calmodulin-regulated protein phosphatase. By using enzyme-immunoassay and immunocytochemistry with an affinity-purified specific antibody to this protein, we have found that calcineurin is expressed in the central and peripheral neuroendocrine cells, also termed amine precursor uptake and decarboxylation cells. In addition, calcineurin immunoreactivity was found in the central neuroendocrine neoplasms such as pineocytoma, olfactory neuroblastoma and paraganglioma. The present findings indicate that the activity of phosphatase regulated by calcium and calmodulin is involved in neuroendocrine functions, and that the enzyme can be useful for the identification and characterization of neuroendocrine cell tumors.
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PMID:Calcineurin, a calcium/calmodulin-regulated protein phosphatase, in mammalian neuroendocrine cells and neoplasms. 133 5

The trimeric form of protein phosphatase 2A (PP2A1 or polycation-stimulated protein phosphatase H1) was purified to homogeneity from rabbit skeletal muscle. Preparative SDS-polyacrylamide gel electrophoresis was used to purify the individual subunits with relative molecular masses of 36, 55, and 65 kDa. Sequence analysis of five peptides from the 65-kDa regulatory subunit (PR65) suggested that it was identical with the PR65 subunit derived from the dimeric protein phosphatase 2A2. Amino acid sequences derived from the 55-kDa regulatory subunit (PR55) were used to clone human and rabbit cDNAs encoding this protein. The PR55 subunit was found to be encoded by two genes, termed alpha and beta. The open reading frames of the PR55 alpha and beta cDNAs spanned 1341 and 1329 nucleotides, respectively, and predicted proteins with a molecular mass of about 52 kDa that are 86% identical. Comparison of the human PR55 amino acid sequences with the data obtained from the rabbit skeletal muscle protein and a partial rabbit PR55 beta cDNA clone indicated a high degree of conservation. Analysis of the mRNA expression in human cell lines revealed that the PR55 alpha isoform was encoded by two transcripts of about 2.3 and 2.5 kb and a less abundant 4.4-kb mRNA. Whereas a PR55 beta transcript of about 2.3 kb was detected at high levels in the neuroblastoma derived cell line LA-N-1, the level of the mRNA was very low in the other human cell lines analyzed. Interestingly, the PR55 sequence showed limited homology to the catalytic domain (domains VI-IX) of the c-abl protein tyrosine kinase.
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PMID:Structure of the 55-kDa regulatory subunit of protein phosphatase 2A: evidence for a neuronal-specific isoform. 184 34

The ATP.Mg-dependent protein phosphatase activating factor (protein kinase FA) has been identified to exist in neuroblastoma x glioma hybrid 108-15 cells (NG108-15 cells). More importantly, when NG cells were induced to differentiate with N6, O2'-dibutyryl adenosine 3',5'-cyclic monophosphate (dibutyryl cAMP), the cellular activity of kinase FA was found to increase dramatically. Time course study further revealed that induction of differentiation in NG cells by dibutyryl cAMP treatment increased the FA activity to over 3 times the levels found in undifferentiated cells and in a linear day-dependent manner, indicating that the FA activity level is correlated with the state of differentiation of NG108-15 cells. This is the first report providing initial evidence that protein kinase FA (a transmembrane signal of insulin) is involved in the induction of neuronal cell differentiation.
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PMID:Cyclic AMP induces activity increase of kinase FA (a transmembrane signal of insulin) during NG108-15 hybrid cell differentiation. 216 38

Calmodulin (CaM)-dependent enzymes, such as CaM-dependent phosphodiesterase (CaM-PDE), CaM-dependent protein phosphatase (CN), and CaM-dependent protein kinase II (CaM kinase II), are found in high concentrations in differentiated mammalian neurons. In order to determine whether neuroblastoma cells express these CaM-dependent enzymes as a consequence of cellular differentiation, a series of experiments was performed on human SMS-KCNR neuroblastoma cells; these cells morphologically differentiate in response to retinoic acid and phorbol esters [12-O-tetradecanoylphorbol 13-acetate (TPA)]. Using biotinylated CaM overlay procedures, immunoblotting, and protein phosphorylation assays, we found that SMS-KCNR cells expressed CN and CaM-PDE, but did not appear to have other neuronal CaM-binding proteins. Exposure to retinoic acid, TPA, or conditioned media from human HTB-14 glioma cells did not markedly alter the expression of CaM-binding proteins; 21-day treatment with retinoic acid, however, did induce expression of novel CaM-binding proteins of 74 and 76 kilodaltons. Using affinity-purified polyclonal antibodies, CaM-PDE immunoreactivity was detected as a 75-kilodalton peptide in undifferentiated cells, but as a 61-kilodalton peptide in differentiated cells. CaM kinase II activity and subunit autophosphorylation was not evident in either undifferentiated or neurite-bearing cells; however, CaM-dependent phosphatase activity was seen. Immunoblot analysis with affinity-purified antibodies against CN indicated that this enzyme was present in SMS-KCNR cells regardless of their state of differentiation. Although SMS-KCNR cells did not show a complete pattern of neuronal CaM-binding proteins, particularly because CaM kinase II activity was lacking, they may be useful models for examination of CaM-PDE and CN expression. It is possible that CaM-dependent enzymes can be used as sensitive markers for terminal neuronal differentiation.
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PMID:Expression of calmodulin-dependent phosphodiesterase, calmodulin-dependent protein phosphatase, and other calmodulin-binding proteins in human SMS-KCNR neuroblastoma cells. 254 Feb 70

To investigate the regulation of posttranslational modifications of tau that might be pertinent to the production of the paired helical filament (PHF) of Alzheimer's disease, we incubated human neuroblastoma cells with the protein phosphatase inhibitor okadaic acid. This treatment results in increased immunoreactivity of tau with the monoclonal antibodies Alz-50, PHF-1, T3P, and NP8, a reduction in Tau-1 immunoreactivity, and an elevation in apparent molecular weight of tau. Moreover, our data demonstrate that accumulation of phosphates in tau leads to a decrease in the turnover rate of tau in the neuroblastoma cells. It is suggested that similar build-up of hyperphosphorylated tau in the neuronal perikarya may represent an early event in PHF formation. The present system facilitates the investigation of regulatory mechanisms governing the occurrence of PHF epitopes, their effects on neuronal cell metabolism, and possible pharmacological intervention.
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PMID:Increased production of paired helical filament epitopes in a cell culture system reduces the turnover of tau. 750 14

Protein phosphorylation and subsequent dephosphorylation was studied in digitonin-permeabilized neuroblastoma SH-SY5Y cells by measuring the incorporation of [32P]phosphate into myelin basic protein (MBP). 1,2-Dioctanoyl-sn-glycerol (DOG) and calcium synergistically induced phosphorylation of MBP, which was inhibited by the protein kinase C (PKC) pseudosubstrate peptide (PKC19-36). The phosphorylation increased for 10 min when a net dephosphorylation started to appear. The dephosphorylation was inhibited by okadaic acid. Regardless of calcium concentration, the presence of DOG was necessary for significant effects of okadaic acid on MBP phosphorylation. H7 and staurosporine dose-dependently inhibited the phosphorylation of MBP, induced by DOG and calcium in the presence of okadaic acid. Different PKC pseudosubstrate peptides were applied and all showed an inhibitory effect on the phosphorylation of MBP under these conditions. These results demonstrate the presence, in SH-SY5Y cells, of a protein phosphatase, possibly protein phosphatase 2A, with a high basal activity that counteracts PKC-induced phosphorylation.
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PMID:An okadaic acid-sensitive protein phosphatase counteracts protein kinase C-induced phosphorylation in SH-SY5Y cells. 768 46

In this study, the signal cascade transducing carbachol stimulation into c-fos expression in SH-SY5Y neuroblastoma cells was investigated. 1,2-Diacylglycerol formation and c-fos expression were mediated via stimulation of muscarinic M1 receptors and the first 5 min of receptor stimulation were critical for these events. Application of 1,2-dioctanoylglycerol induced c-fos expression and this, as well as carbachol-stimulated c-fos expression, was inhibited by protein kinase C inhibitors. Increasing the intracellular Ca2+ concentration had only small effects on c-fos expression. There was a dependency on extracellular Ca2+ for maximal c-fos expression and 1,2-diacylglycerol formation. The carbachol-stimulated c-fos expression was potentiated by application of the protein phosphatase inhibitor okadaic acid. These results demonstrate the importance of 1,2-diacylglycerol formation for muscarinic receptor-stimulated, protein kinase C-mediated c-fos expression in the SH-SY5Y cells and that this cascade is counteracted by an okadaic acid-sensitive protein phosphatase.
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PMID:Mechanisms of muscarinic receptor-stimulated expression of c-fos in SH-SY5Y cells. 792 9

The effects of okadaic acid (OA), a potent and specific inhibitor of serine/threonine phosphatases 2A and 1, on the transient expression of a human hsp 70 promoter-linked chloramphenicol acetyltransferase gene transfected into N-18 mouse neuroblastoma cells were determined. Assays of reporter gene activity showed that nanomolar concentrations of OA markedly potentiated the heat-induced (but not the basal) expression of pHBCAT, a full-length hsp 70 promoter-driven chloramphenicol acetyltransferase gene construct. This effect of OA was dose-dependent and promoter-specific and appeared to be attributable to inhibition of protein phosphatase 2A as opposed to protein phosphatase 1. The ability of OA to potentiate the heat-induced expression of pHBCAT appeared to be a feature common to several different cell types examined. We propose that the heat-induced transcriptional activation of heat shock genes is associated with the phosphorylation of component(s) of the transcription complex and that OA enhances this phosphorylation, thereby potentiating the heat-induced hsp 70 promoter activity.
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PMID:Okadaic acid markedly potentiates the heat-induced hsp 70 promoter activity. 838 Apr 12

GRP78, a molecular chaperone expressed in the endoplasmic reticulum, is a "glucose-regulated protein" induced by stress responses that deplete glucose or intracisternal calcium or otherwise disrupt glycoprotein trafficking. Previously we showed that chronic ethanol exposure increases the expression of GRP78. To further understand the mechanism underlying ethanol regulation of GRP78 expression, we studied the interaction between ethanol and classical modulators of GRP78 expression in NG108-15 neuroblastoma x glioma cells. We found that, in addition to increasing basal levels of GRP78 mRNA ("induction"), ethanol produced greater than additive increases in the induction of GRP78 mRNA by the "classical" GRP inducers A23187, brefeldin A, and thapsigargin ("potentiation"). Both the ethanol induction and potentiation responses modulated grp78 gene transcription as determined by stable transfection analyses with the rat grp78 promoter. Ethanol potentiated the action of all classical inducers of grp78 transcription that were studied. In contrast, co-treatment with the classical GRP inducers thapsigargin and tunicamycin produced only simple additive increases in grp78 promoter activity. Transient transfection studies with deletion mutants of the rat grp78 promoter showed that cis-acting promoter sequences required for ethanol induction differ from those mediating responses to classical GRP inducers. Furthermore, linker-scanning mutations of the grp78 promoter suggested that the ethanol potentiation response required a cis-acting promoter element different from those involved in induction by ethanol or classical inducing agents. While the ethanol induction response required 16-24 h to be detectable, ethanol potentiation of thapsigargin occurred within 6 h. The potentiation response also decayed rapidly after ethanol removal. In addition, the protein kinase A inhibitor Rp-cAMPS and protein phosphatase inhibitor okadaic acid both increased ethanol potentiation of thapsigargin while Sp-cAMPS, an activator of protein kinase A, decreased ethanol potentiation. Taken together, our findings suggest two mechanisms by which ethanol regulates grp78 transcription, both differing from the action of classical GRP inducers such as thapsigargin. One mechanism (potentiation) involves a protein phosphorylation cascade and potentiates the action of classical GRP inducers. In contrast, GRP78 induction by ethanol involves promoter sequences and a mechanistic pathway separate from that of the ethanol potentiation response or classical GRP78 inducers. These studies show that ethanol produces a novel and complex regulation of grp78 transcription which could be of particular importance during neuronal exposure to GRP-inducing stressors as might occur with central nervous system injury.
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PMID:Interaction of ethanol with inducers of glucose-regulated stress proteins. Ethanol potentiates inducers of grp78 transcription. 857 45

Protein phosphatase 2A is a heterotrimeric protein serine/threonine phosphatase consisting of a 36-kDa catalytic C subunit, a 65-kDa structural A subunit, and a variable regulatory B subunit. The B subunits determine the substrate specificity of the enzyme. There have been three families of cellular B subunits identified to date: B55, B56 (B'), and PR72/130. We have now cloned five genes encoding human B56 isoforms. Polypeptides encoded by all but one splice variant (B56gamma1) are phosphoproteins, as shown by mobility shift after treatment with alkaline phosphatase and metabolic labeling with [32P]phosphate. All labeled isoforms contain solely phosphoserine. Indirect immunofluorescence microscopy demonstrates distinct patterns of intracellular targeting by different B56 isoforms. Specifically, B56alpha, B56beta, and B56epsilon complexed with the protein phosphatase 2A A and C subunits localize to the cytoplasm, whereas B56delta, B56gamma1, and B56gamma3 are concentrated in the nucleus. Two isoforms (B56beta and B56delta) are highly expressed in adult brain; here we show that mRNA for these isoforms increases severalfold when neuroblastoma cell lines are induced to differentiate by retinoic acid treatment. These studies demonstrate an increasing diversity of regulatory mechanisms to control the activity of this key intracellular protein phosphatase and suggest distinct functions for isoforms targeted to different intracellular locations.
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PMID:The B56 family of protein phosphatase 2A (PP2A) regulatory subunits encodes differentiation-induced phosphoproteins that target PP2A to both nucleus and cytoplasm. 870 17


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