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)

A xylanolytic amyloglucosidase of Termitomyces clypeatus was characterised with respect to other amyloglucosidases. The enzyme contained high alpha-helix destabilising amino acids but no sulphur amino acid. It contained high threonine and serine, analogous to other raw starch hydrolysing enzymes. Both xylanase and amyloglucosidase activities were gradually lost with the progress of tryptophan oxidation by NBS and total inactivation occurred after oxidation of 4-5 tryptophan residues. In the presence of substrates (either starch or xylan), complete inactivation of either activities was not noticed even after oxidation of 7.7 mol of tryptophan residues. Inactivation by HNBB was not possible in the absence of any denaturant. Only 4.9 mol of tryptophan could be modified in the presence of 5 M urea which resulted in only 42% inhibition of activity. Thus modified enzyme had higher Vm/Km and lower pH optima in comparison to those of native enzyme. It was suggested that tryptophan was present at the substrate binding site and not at the active site. No such change in activity was noticed after modification of tyrosine, lysine or arginine residues. HPGPLC analysis of both dilute and concentrated enzyme solution indicated that the enzyme existed as an equilibrium mixture of protomer-oligomer. Perhaps for this reason molar mass of NAI modified enzyme appeared to be almost half of that modified by NAI in presence of substrate. Arrhenius plot of the enzyme also indicated reversible oligomerisation as a function of temperature.
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PMID:Characterisation of a xylanolytic amyloglucosidase of Termitomyces clypeatus. 918 49

Loss of heterozygosity (LOH) on chromosome 18q21 is found frequently in various human cancers. Three candidate tumor suppressor genes, DCC (deleted in colorectal carcinomas), DPC4 (deleted in pancreatic carcinomas, locus 4), and MADR2/JV18-1 (MAD-related gene 2), have been cloned and identified from this chromosome region. We have reported recently that LOH on chromosome 18q is observed frequently in neuroblastoma. Alterations of DCC are involved in many human tumors. DPC4 and MADR2/JV18-1 are recently demonstrated to be altered in pancreatic and colorectal cancers, respectively. To confirm if inactivation of the DCC, DPC4, and MADR2/JV18-1 genes is involved in the pathogenesis of neuroblastoma and to clarify the mechanism of inactivation, we analyzed the expression of DCC, DPC4, and MADR2/JV18-1 in neuroblastoma cell lines and primary tumors by reverse transcription-PCR and investigated the mutations in the coding regions of these genes by PCR/reverse transcription-PCR single-strand conformation polymorphism. We found that 12 of 25 (48%) cell lines and 14 of 32 (44%) primary tumors, including 3 with 18q LOH, had absent or reduced expression of DCC mRNA. Expression was more likely to be reduced in advanced (67%) than in early stage neuroblastomas (24%) (P = 0.036), suggesting that inactivation of the DCC gene plays an important role in the progression of neuroblastoma. Altered expression of DPC4 was found in six (24%) cell lines and six (19%) tumors. MADR2/JV18-1 expression was reduced or absent only in four (16%) cell lines and three (9%) tumors. Mutations of the DCC genes were examined in 25 of 29 exons in neuroblastoma cell lines, and those exons in which mutations were found were further examined in primary tumors. We found missense mutations of AAC (Asn) to AGC (Ser) at DCC codon 176 in one cell line and ACC (Thr) to ATC (Ile) at codon 1105 in one cell line and tumor, respectively; polymorphisms of CGA (Arg) to GGA (Gly) at codon 201 and TTT (Phe) to TTG (Leu) at codon 951 in most of the cell lines and tumors; and a silent mutation of GAG (Glu) to GAA (Glu) at codon 118 in four cell lines and five primary tumors. We did not identify any mutations in the DPC4 and MADR2/JV18-1 genes in neuroblastoma. Our results suggested that mutations of the DCC gene may be involved in the pathogenesis of neuroblastomas but failed to account for the relatively high frequency of the altered expression, implying that other mechanisms are responsible for the inactivation of the DCC gene in neuroblastoma. Low frequency of reduced or absent mRNA expression and lack of mutations in DPC4 and MADR2/JV18-1 genes suggested a limited role for these two genes in neuroblastoma.
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PMID:Expression and mutational analysis of the DCC, DPC4, and MADR2/JV18-1 genes in neuroblastoma. 928 86

The possible involvement of protein phosphatase in ceramide-mediated neural cell differentiation was investigated. Neuroblastoma Neuro2a cell differentiation induced by retinoic acid, or conditions causing an increase in cellular ceramide, was significantly inhibited by the serine/threonine phosphatase inhibitor okadaic acid, at concentrations as low as 2.5 nM. A crude cytosolic preparation from Neuro2a cells was found to have a cation-independent protein phosphatase activity that was stimulated by ceramide in a dose-dependent manner. Short- and long-chain ceramides, but not sphingosine and related dihydro-derivatives, were active. Ceramide-activated protein phosphatase activity from Neuro2a cells was inhibited by 5 nM okadaic acid. The data indicate that a type 2A protein phosphatase is involved in ceramide-mediated differentiation of Neuro2a cells.
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PMID:Involvement of a ceramide activated protein phosphatase in the differentiation of neuroblastoma Neuro2a cells. 931 44

1. To approach the mechanisms underlying desensitization of the opioid receptor-mediated Ca2+ channel inhibition, the effects of prolonged application of [D-Ala2, D-Leu5]enkephalin (DADLE) on Ba2+ currents (I(Ba)) through Ca2+ channels were analysed in NG108-15 neuroblastoma x glioma hybrid cells. 2. Inhibition of I(Ba) by 100 nM DADLE desensitized by 57% with a time constant of 4.4 min. 3. Maximal desensitization of the delta-opioid receptor-Ca2+ channel coupling was attained by 1 microM DADLE. The EC50 value for desensitization was estimated to be 78 nM. 4. RNA blot hybridization analysis and immunoblot analysis revealed the expression of beta-adrenoceptor kinase-1 (betaARK1) in NG108-15 cells. 5. Heparin, an inhibitor of betaARK, significantly reduced the magnitude and rate of desensitization, whereas Rp-cyclic AMPS and PKI (14-24)amide, inhibitors of cyclic AMP-dependent protein kinase (PKA), or long-term treatment with phorbol 12-myristate 13-acetate to induce down-regulation of protein kinase C (PKC) had no significant effect. 6. Recovery from desensitization (resensitization) proceeded with a time constant of 6.7 min. Okadaic acid, an inhibitor of serine/threonine phosphatases 1 and 2A, significantly attenuated the degree of resensitization. 7. In summary, we have characterized the time course and concentration-dependence of the desensitization of DADLE-induced I(Ba) inhibition in NG108-15 cells. This desensitization was reversible after removal of DADLE. It is suggested that betaARK, but neither PKA nor PKC, is involved in desensitization, while serine/threonine phosphatases mediate resensitization.
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PMID:Desensitization and resensitization of delta-opioid receptor-mediated Ca2+ channel inhibition in NG108-15 cells. 955 94

Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) is one of the most abundant protein kinases in the brain and has a broad substrate specificity [M.K. Bennett, N.E. Erondu, M.B. Kennedy, Purification and characterization of a calmodulin-dependent protein kinase that is highly concentrated in brain, J. Biol. Chem. 258 (1983) 12735-12744 [1]; J.R. Goldenring, B. Gonzalez, J.S. McGuire, Jr., R.J. DeLorenzo, Purification and characterization of a calmodulin-dependent kinase from rat brain cytosol able to phosphorylate tubulin and microtubule-associated proteins, J. Biol. Chem. 258 (1983) 12632-12640 [4]; M.B. Kennedy, P. Greengard, Two calcium/calmodulin-dependent protein kinases, which are highly concentrated in brain, phosphorylate protein I at distinct sites, Proc. Natl. Acad. Sci. U.S.A. 78 (1981) 1293-1297 [10]; T. Yamauchi, H. Fujisawa, Evidence for three distinct forms of calmodulin-dependent protein kinases from rat brain, FEBS Lett. 116 (1980) 141-144 [20]; T. Yamauchi, H. Fujisawa, Purification and characterization of the brain calmodulin-dependent protein kinase (kinase II), which is involved in the activation of tryptophan 5-monooxygenase, Eur. J. Biochem. 132 (1983) 15-21 [21]]. The alpha and beta isoforms of CaM kinase II are known to be expressed almost exclusively in the brain [P.I. Hanson, H. Schulman, Ca2+/calmodulin-dependent protein kinases, Annu. Rev. Biochem. 61 (1992) 559-601 [7]]. To elucidate the cellular function of CaM kinase II, we introduced cDNA of wild-type CaM kinase II alpha- or beta-isoform, and of mutant alpha-isoform (Ala-286 kinase) into two different types of neuroblastoma, Neuro2a (Nb2a) and NG108-15, thus generating cell lines stably producing elevated levels of these kinases. The mutant alpha-isoform is markedly suppressed in its autophosphorylation by replacement of Thr-286 with Ala [Y.-L. Fong, W.L. Taylor, A.R. Means, T.R. Soderling, Studies of the regulatory mechanism of Ca2+/calmodulin-dependent protein kinase II. Mutation of threonine 286 to alanine and aspartate, J. Biol. Chem. 264 (1989) 16759-16763 [3]; P.I. Hanson, M.S. Kapiloff, L.L. Lou, M.G. Rosenfeld, H. Schulman, Expression of a multifunctional Ca2+/calmodulin-dependent protein kinase and mutational analysis of its autoregulation, Neuron 3 (1989) 59-70 [6]; S. Ohsako, H. Nakazawa, S. Sekihara, A. Ikai, T. Yamauchi, Role of Threonine-286 as autophosphorylation site for appearance of Ca2+-independent activity of calmodulin-dependent protein kinase II alpha subunit, J. Biochem. 109 (1991) 137-143 [15]]. We provided evidence that CaM kinase II played a role in regulating neurite outgrowth and growth cone motility in these cells, and that the autophosphorylation is essential for the kinase to sufficiently exert its cellular function in vivo [Y. Goshima, S. Ohsako, T. Yamauchi, Overexpression of Ca2+/calmodulin-dependent protein kinase II in Neuro2a and NG108-15 neuroblastoma cell lines promotes neurite outgrowth and growth cone motility, J. Neurosci. 13 (1993) 559-567 [5]]. Neurite outgrowth was further stimulated by treatment with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) or chelerythrine, inhibitors of protein kinase C [T. Nomura, K. Kumatoriya, Y. Yoshimura, T. Yamauchi, Overexpression of alpha and beta isoforms of Ca2+/calmodulin-dependent protein kinase II in neuroblastoma cells-H-7 promotes neurite outgrowth, Brain Res. 766 (1997) 129-141 [14]]. The morphological change stimulated with protein kinase inhibitors was rapid and was greater in the beta than alpha cells. Some substrates of CaM kinase II related to neurite outgrowth were detected in cells overexpressing the kinase stimulated with H-7. These results suggest that CaM kinase II and protein kinase C play an important role in the control of cell change. (c) 1998 Elsevier Science B.V. All rights reserved.
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PMID:Neurite outgrowth of neuroblastoma cells overexpressing alpha and beta isoforms of Ca2+/calmodulin-dependent protein kinase II-effects of protein kinase inhibitors. 963 Jun 58

Alanyl aminopeptidase (AAP-S) was purified to homogeneity from rat liver cytosol. The molecular weight of the purified enzyme was calculated to be approximately 100,000 on Sephacryl S-200 HR and to be 90,000 on SDS-PAGE in the presence of beta-mercaptoethanol. These findings suggested that the enzyme exists as a monomeric form in rat liver cytosol. The enzyme rapidly hydrolyzed the substrates Ala-, Tyr- and Met-MCAs, and moderately hydrolyzed Arg-, Lys-, Leu-, Phe- and Lys-Ala-MCAs at pHs ranging from 7.5to 8.0. The enzyme also hydrolyzed several amino acid 4-methyl-coumaryl-7-amide (MCA) substrates. The order for k(cat)/Km values of AAP-S at the optimal pH (pH 7.5) was Lys->Met->Arg->Ala->Leu->Phe->Tyr->Lys-Ala-MCAs. It was strongly inhibited by bestatin, leuhistin, actinonin, amastatin, 1, 10-phenanthroline, PCMBS, Zn2+, Cd2+, Co2+, Cu2+ and Hg2+, and puromycin. The amino acid sequence of the first 43 residues of the enzyme was determined as Pro1-Glu-Lys-Arg-Pro5-Phe-Glu-Arg-Leu-Pro10-Thr-Glu-Val-Ser-Pro 15-Ile-Asn-Tyr-Ser-Leu20-(Cys)-Leu-Lys-Pro-Asp25-Leu-Leu- Asp-Phe-Thr30-Phe-Glu-Gly-Lys-Leu35-Glu-Ala-Ala-Ala-Gln40 -Val-Arg-Gln-. This N-terminal amino acid sequence is almost identical with those of puromycin-sensitive enkephalin-degrading aminopeptidases in rat and human brains, and the mouse neuroblastoma cell line Neuro2A. These findings suggest that the AAP-S from rat liver cytosol is a puromycin-sensitive aminopeptidase. Furthermore, with immunohistochemistry the enzyme was strongly stained in the cytosol of the rat liver cells.
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PMID:Isolation and characterization of an alanyl aminopeptidase from rat liver cytosol as a puromycin-sensitive enkephalin-degrading aminopeptidase. 968 21

Tau protein, a neuronal microtubule-associated protein is phosphorylated on several sites when extracted from brain tissue and is a substrate for many protein kinases in vitro. In Alzheimer's disease it becomes hyperphosphorylated, notably at Ser-Pro or Thr-Pro motifs, and forms the paired helical filaments (PHFs). The increased phosphorylation can be detected by several antibodies raised against Alzheimer tau. We show here that a similar type of phosphorylation can be observed in cells of neuronal origin during mitosis. Murine neuroblastoma cells (N2a) were stably transfected with htau40, the largest of the six human tau isoforms in the brain. We used several antibodies reporting on the state of phosphorylation of tau (Tau-1, AT8, AT180, PHF-1, and T46) and the antibody MPM-2 that recognizes phosphorylated mitotic proteins. The results show that tau is in a state of low phosphorylation in interphase cells, whereas during mitosis it becomes highly phosphorylated. This behavior was also found for endogenous tau protein in human neuroblastoma cells (LAN-5). The similarity between tau phosphorylation in dividing neuronal cells and Alzheimer degenerating neurons may indicate that aging neurons exposed to inappropriate signals respond by an attempt to activate their machinery for regeneration.
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PMID:Mitotic phosphorylation of tau protein in neuronal cell lines resembles phosphorylation in Alzheimer's disease. 971 64

Phosphorylation of brain spectrin was studied by a combination of in vivo and in vitro approaches. Chemical analysis of phosphate groups on electrophoretically purified mouse brain beta-spectrin yielded a stoichiometry of 3.2 +/- 0.18 mol of PO4/mol of beta-spectrin. The spectrin isolated by chromatographic methods from mouse brain, pig brain, and human erythrocytes yielded 4.1, 5.6, and 3.2 mol of PO4/mol of spectrin heterodimer, respectively. The 32P labeling of spectrin in retinal ganglion cell neurons or NB 2a/d1 neuroblastoma cells with [32P]orthophosphate showed phosphorylation of only beta-spectrin in vivo. Two-dimensional phosphopeptide map analyses showed that most of the in vivo sites on beta-spectrin were phosphorylated by either a heparin-sensitive endogenous cytoskeleton-associated protein kinase or protein kinase A. Phosphoamino acid analysis of in vivo and in vitro phosphorylated beta-spectrin showed that [32P]phosphate groups were incorporated into both serine (>90%) and threonine residues. In vitro, phosphate groups were incorporated into threonine residues by the heparin-sensitive endogenous protein kinase. The amino acid sequence VQQQLQAFNTY of an alpha-chymotryptic 32P-labeled peptide phosphorylated by the heparin-sensitive cytoskeleton-associated endogenous protein kinase corresponded to amino acid residues 338-348 on the beta1 repeat of beta-spectrinG (betaSPIIa) gene. These data suggest that phosphorylation of Thr347, which is localized on the presumptive synapsin I binding domain of beta-spectrinG, may play a role in synaptic function by regulating the binding of spectrin to synaptic vesicles.
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PMID:Brain beta-spectrin phosphorylation: phosphate analysis and identification of threonine-347 as a heparin-sensitive protein kinase phosphorylation site. 979 50

Insulin-like growth factor I (IGF-I) is a potent neurotropic factor promoting the differentiation and survival of neuronal cells. SH-SY5Y human neuroblastoma cells are a well characterized in vitro model of nervous system growth. We report here that IGF-I stimulated the tyrosine phosphorylation of the type I IGF receptor (IGF-IR) and insulin receptor substrate-2 (IRS-2) in a time- and concentration-dependent manner. These cells lacked IRS-1. After being tyrosine phosphorylated, IRS-2 associated transiently with downstream signaling molecules, including phosphatidylinositol 3-kinase (PI 3-K) and Grb2. Treatment of the cells with PI 3-K inhibitors (wortmannin and LY294002) increased IGF-I-induced tyrosine phosphorylation of IRS-2. We also observed a concomitant increase in the mobility of IRS-2, suggesting that PI 3-K mediates or is required for IRS-2 serine/threonine phosphorylation, and that this phosphorylation inhibits IRS-2 tyrosine phosphorylation. Treatment with PI 3-K inhibitors induced an increased association of IRS-2 with Grb2, probably as a result of the increased IRS-2 tyrosine phosphorylation. However, even though the PI 3-K inhibitors enhanced the association of Grb2 with IRS-2, these compounds suppressed IGF-I-induced mitogen-activated protein kinase activation and neurite outgrowth. Together, these results indicate that although PI 3-K participates in a negative regulation of IRS-2 tyrosine phosphorylation, its activity is required for IGF-IR-mediated mitogen-activated protein kinase activation and neurite outgrowth.
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PMID:Differential regulation of insulin receptor substrate-2 and mitogen-activated protein kinase tyrosine phosphorylation by phosphatidylinositol 3-kinase inhibitors in SH-SY5Y human neuroblastoma cells. 983 24

Signaling of G protein-coupled receptors is terminated by phosphorylation of intracellular serine and threonine residues. Resensitization of these receptors requires internalization and subsequent dephosphorylation. We have recently shown that the resensitization rate of the rat micro opioid receptor (MOR) isoforms MOR1 and MOR1B is mainly determined by the amino acid composition of their alternatively spliced C-terminal tails. Upon agonist stimulation, MOR1B passes through an accelerated cycle of receptor endocytosis and reactivation, which in turn promotes a greater resistance to agonist-induced desensitization, as compared with MOR1. Given the fact that MOR1B lacks only one putative phosphorylation site (T394 of MOR1), we replaced this threonine by an alanine and stably expressed the wild-type MOR1 and its T394A mutant in mouse neuroblastoma Neuro2a cells. We show that during prolonged [D-Ala2, MePhe4, Gly5-ol]enkephalin exposure (5 h), the T394A receptor mutant desensitized at a slower rate than MOR1. In contrast, T394A is more rapidly removed from the cell surface than MOR1, as determined by flow cytometry using epitope-tagged receptors. This fast internalization was followed by immediate resensitization of T394A during 20 min of agonist removal while the wild-type MOR1 remained inactive. Similar to MOR1B, rapid internalization and reactivation of T394A may explain its delayed desensitization. These findings suggest that T394 represents a negative regulatory signal for MOR1 internalization. Furthermore, phosphorylation of this threonine residue may influence the time course of micro opioid receptor resensitization.
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PMID:Replacement of threonine 394 by alanine facilitates internalization and resensitization of the rat mu opioid receptor. 992 17


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