Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activities of two DNA polymerases (DNA nucleotidyltransferases) were characterized in mouse neuroblastoma clone N-18 on the basis of their apparent molecular weights (determined by sucrose density gradient centrifugation: polymerase-alpha, 7.5-8 S; polymerase-beta, 3-4 S) and relative inhibition by sulfhydryl-blocking agents. N-Ethylmaleimide (10 mM) and iodoacetamide (1.5 mM) inhibited DNA polymerase-alpha activity completely, whereas only 35-40% inhibition was observed for DNA polymerase-beta under similar conditions. DNA polymerase-alpha activity was reduced 50-70% in N-18 cells that had been induced to differentiate by 4 micro M bromodeoxyuridine, and the low molecular weight DNA polymerase-beta activity remain unchanged. With activated calf thymus DNA as template, only DNA polymerase-alpha activity was stimulated in the presence of added ribonucleotides and purified Escherichia coli RNA polymerase.
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PMID:DNA polymerase activities in differentiating mouse neuroblastoma N-18 cells. 27 18

Neuropeptide Y (NPY) and peptide YY (PYY) are structurally related peptides that primarily function as neurotransmitter and gastrointestinal hormone, respectively. Previous functional and binding data have indicated the existence of at least three distinct receptor types, Y1, Y2, and Y3, for NPY and/or PYY in mammals. We describe here a human Y1 cDNA clone, hY1-5, isolated from a fetal brain library. The human Y1 receptor consists of 384 amino acids and has seven putative transmembrane domains like other members of the G-protein-coupled superfamily of receptors. In the region spanning the transmembrane domains, the Y1 receptor displays 29% sequence identity to human tachykinin receptors, but it only shows 21% and 23% homology with proposed bovine (LCR1) and Drosophila (PR4) NPY receptor clones, respectively. Northern blot analysis of a human neuroblastoma cell line, SK-N-MC, previously used by many investigators as a model system for studies on the Y1 receptor, revealed a single 3.5-kilobase mRNA species. Reverse transcriptase-polymerase chain reaction analysis indicated expression also in human cultured vascular smooth muscle cells, supporting the view that the Y1 receptor is associated with NPY/PYY-evoked vasoconstriction. When expressed in COS1 cells, hY1-5 conferred specific 125I-PYY binding sites with displacement patterns characteristic of the Y1 receptor, i.e. PYY greater than or equal to NPY greater than or equal to [Leu31,Pro34]NPY much greater than NPY2-36 greater than C2NPY greater than pancreatic polypeptide greater than NPY13-36 greater than NPY18-36. Moreover, in the Y1 receptor-transfected COS1 cells, but not in type 1 angiotensin II receptor-transfected control cells, NPY and PYY accelerated 45Ca2+ influx and inhibited forskolin-stimulated cAMP accumulation, both phenomena being characteristic of the mammalian Y1 receptor.
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PMID:Cloning and functional expression of a human neuropeptide Y/peptide YY receptor of the Y1 type. 131 48

Infectivity of human T-lymphotropic virus type I (HTLV-I) to human nervous tissue cells was explored using co-cultivation with X-irradiated, HTLV-I-producing MT2 cells. Examined cells included normal cerebellar cells, brain tumor cells (astrocytoma, medulloblastoma, meningioma, hemangioblastoma, and schwannoma), and various cell lines (astrocytoma, ependymoma, oligodendroglioma, medulloblastoma, and neuroblastoma). Successful HTLV-I infection was confirmed immunohistochemically using monoclonal antibodies to HTLV-I p19, p24, and pX product. All cell lines and primary cultures from normal cerebellar tissues and brain tumors could be infected with HTLV-I. Double immunostaining showed that glial fibrillary acidic protein-, S-100 protein- or vimentin-positive cells were susceptible to infection. Neurofilament- or neuron-specific enolase-positive cells in medulloblastoma could also be infected. Reverse-transcriptase assay revealed the productive infection in U251-MG (astrocytoma) and KG-IC (oligodendroglioma) lines. Co-cultivated U251-MG cells formed syncytial polykaryons after serial passages, and polymerase chain reaction assay detected HTLV-I genome in U251-MG syncytial polykaryons and p19+ mononuclear cells. HTLV-I viral RNA was also detected in infected U251-MG cells by in situ hybridization. These data show that HTLV-I may have a wide spectrum of infectivity in human nervous tissues.
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PMID:Infectivity of human T-lymphotropic virus type I to human nervous tissue cells in vitro. 138 59

Two clones have been selected from a human fibroblast cDNA bank. By DNA sequencing the clones were shown to contain Alu elements located near the ends of the cDNA inserts. DNA of the clones was used for Northern blot hybridization analysis of a number of poly(A)-containing RNAs from normal human tissues (brain, stomach, uterus, spleen, fibroblasts) and tumors (neurinoma, glioma, neuroblastoma, liposarcoma, adrenal cortex adenocarcinoma). All RNA samples reveal a heterodisperse distribution of Alu transcripts with discrete bands in the region of 7-12 S RNA. The majority of these small poly(A)+ Alu+ RNAs contain Alu sequences only in one (canonical) orientation with functional signals including the split promoter for RNA polymerase III.
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PMID:Cloning of Alu-containing cDNAs from human fibroblasts and identification of small Alu+ poly(A)+ RNAs in a variety of human normal and tumor cells. 243 58

Previous work demonstrated two stimulatory effects of methyl mercury on nucleic acid synthesis: (1) in isolated nuclei, methyl mercury stimulates RNA synthesis which is catalyzed by RNA polymerase II [Frenkel and Randles, J. Biol. Chem. 257, 6275-6279 (1982)]. (2) Brief exposure of purified DNA to methyl mercury increases the rate of its transcription by purified RNA polymerase II [Frenkel, Cain, and Chao, Biochem. Biophys. Res. Commun. 127, 849-856 (1985)]. The latter effect was considered as a possible mechanism of the former. Two lines of evidence are presented here which demonstrate that the latter effect is not a sufficient explanation for the former. (1) Mercuric perchlorate has been found to increase the rate of DNA transcription by purified polymerase and the template properties of the mercuric perchlorate-exposed DNA have been found to resemble those of methyl mercury-exposed DNA. Nevertheless, mercuric perchlorate has been shown not to stimulate RNA synthesis in isolated HeLa nuclei. (2) In isolated nuclei of the B50 rat neuroblastoma cell line, RNA synthesis has been found to be stimulated only minimally by methyl mercury. Nevertheless, RNA polymerase II purified from the B50 cells has been found to transcribe methyl mercury-exposed DNA at a higher rate than unexposed control DNA.
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PMID:The enhanced rate of transcription of methyl mercury-exposed DNA by RNA polymerase is not sufficient to explain the stimulatory effect of methyl mercury on RNA synthesis in isolated nuclei. 244 20

Six temperature-sensitive (ts) mutants of vesicular stomatitis virus (VSV) isolated from the central nervous system (CNS) following injection with ts G31 (III) all possessed a post-transcriptional defect, not found in the initial virus, that affects the stability of viral RNA transcripts. Examination of viral RNA metabolism in mouse neuroblastoma (N-18) cells revealed that RNA synthesis of the CNS isolates was decreased considerably at elevated temperatures (up to 80 or 90% at 39 degrees C). In addition, analysis of the RNA transcripts suggested that little if any normal-sized transcripts were made in cells infected with these CNS isolates at either 37 degrees C or 39 degrees C. The RNA deficiencies did not appear to be the result of a temperature-sensitive lability of virion transcriptase as examined by in vitro transcriptase assays. However, when N-18 cells infected with one of the CNS isolates, ts G31 BP, were first preincubated at the permissive temperature of 31 degrees C for 3 h and then shifted to 39 degrees C, RNA synthesis proceeded at a rate comparable to that of 31 degrees C. The viral mRNA species synthesized following the temperature shift also contained normal sized tracts of poly(A) RNA, suggesting that neither the viral transcriptase nor its polyadenylate synthetase was thermally labile. However, for any of the six CNS isolates, all species of viral RNA synthesized in cells that were first preincubated at 31 degrees C degraded rapidly when the cells were shifted to 39 degrees C. In contrast little or no RNA degradation of either 42S progeny RNA or mRNA species was detected in the wild-type VSV, ts G31 or three other VSV mutants that are defective in some aspect of viral RNA metabolism: [ts G11 (I), ts G22 (II), ts G41 (IV)]. The apparent phenotype alteration in the stability of viral RNA in all of these CNS isolates is discussed in terms of the possible genotypic changes that may have occurred as well a the unique CNS disease that accompanies infection by these viruses.
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PMID:RNA degradation defect in central nervous system isolates of vesicular stomatitis virus. 616 98

Plasmacytomagenesis provides a murine model to decipher progressive genetic events culminating in a B-cell neoplasia. Activation of the c-myc protooncogene by chromosomal translocation is considered an initiating event. Intracisternal A-type particles (IAPs) are defective retroviral-like structures present in the endoplasmic reticulum of plasmacytomas (PCTs). IAP proviral insertions have been documented to engender negative or positive effects on the expression of nearby cellular genes. We have isolated a gene, PANG (plasmacytoma-associated neuronal glycoprotein), that is ectopically transcribed in a number of PCTs due to IAP long terminal repeat (LTR) activation. A full-length PANG cDNA was isolated from an MPC-11 plasma cell tumor cDNA library and encodes a polypeptide of about 113 kDa with six immunoglobulin C2-like and four type III fibronectin-like domains. PANG bears a striking resemblance to axonal glycoproteins TAG-1 and F11 known to function in neuronal outgrowth. An extensive survey revealed a predominant 3.6-kb PANG transcript in 60% (30 of 50) of PCTs as well as unique smaller and larger species. All other normal and transformed lymphoid and nonlymphoid cell lines and normal tissues were negative for PANG expression except for the brain, wherein unique 4.0- and 6.1-kb transcripts were detected. Reverse transcriptase PCR analysis revealed IAP LTR fusion to PANG mRNAs in five PCTs and in a neuroblastoma line. The 5' end of a mouse brain PANG cDNA was identical to the MPC-11 PANG transcript except for the precise replacement of its 5' LTR sequence.
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PMID:PANG, a gene encoding a neuronal glycoprotein, is ectopically activated by intracisternal A-type particle long terminal repeats in murine plasmacytomas. 810 13

Cholinergic neurons in PNS and CNS are identified by the presence of choline acetyltransferase and the accumulation of choline by a high-affinity, sodium-coupled choline transporter to be used for acetylcholine synthesis. It appears that expression of choline acetyltransferase can be altered by several physiological conditions, including hormones and trophic factors, but little is known about control of expression of the sodium-coupled choline carrier or whether these two phenotypic markers are regulated similarly. In the present study, the cholinergic human neuroblastoma LA-N-2 was used to investigate regulation of expression of choline acetyltransferase and choline uptake activity associated with differentiation and neurite extension. Cells grown in serum-containing basal medium maintained a relatively undifferentiated morphology, expressed low levels of choline acetyltransferase activity, and accumulated choline by a sodium-dependent process followed by conversion to acetylcholine. Transfer of cells to an enriched, serum-free defined medium resulted in morphological and neurochemical differentiation, with an enhancement of cholinergic phenotype. Hemicholinium-sensitive choline uptake activity was increased about sixfold over a 4-day period, with no change in choline acetyltransferase or acetylcholinesterase specific activity. Acetylcholine synthesis was increased in parallel with the changes in choline accumulation; choline metabolism in the differentiated cells differed significantly from that observed in the undifferentiated cells, with proportionally less converted to phosphorylcholine and proportionally more remaining as unmetabolized choline and converted to acetylcholine. The enhanced choline accumulation appeared to be mediated by an increased number of choline carriers, demonstrated by increased binding of the affinity ligand [3H]-choline mustard to the transporter and by an increased Vmax for the uptake process. The increased expression of the transport function appeared to be under transcriptional control, as the enhancement of uptake was blocked by the RNA polymerase II inhibitor alpha-amanitin as well as by the protein synthesis inhibitor cycloheximide. These results show that expression of sodium-coupled choline carriers and choline acetyltransferase may be regulated separately in the differentiating neuroblastoma LA-N-2 and that neurotransmitter synthesis is controlled by provision of precursor rather than at the level of the biosynthetic enzyme.
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PMID:Regulation of expression of cholinergic neuronal phenotypic markers in neuroblastoma LA-N-2. 837 93

Neuroblastoma (NB) is a major-histocompatibility-complex(MHC)-negative neuroectodermal tumour that is often infiltrated with lymphocytes. A detailed characterization of NB-associated tumour-infiltrating lymphocytes (TIL) has never been carried out. Here we have investigated the immunophenotype and the cytotoxic activities of TIL from nine and seven NB patients respectively. Furthermore, the T cell receptor (TcR) variability and the patterns of cytokine gene expression of fresh versus recombinant (r) interleukin (IL)-2-cultured TIL were studied in four NB cases. The results obtained showed the following: (1) freshly isolated TIL were comprised of a mixture of CD4+ and CD8+ T cells partially expressing HLA-DR and/or CD25. The CD4/CD8 ratio ranged from 0.5 to 5 in the different cases. Upon culture of TIL with rIL-2, an increased proportion of CD56+ and CD8+ lymphocytes was consistently observed; (2) IL-2-expanded TIL lysed natural-killer(NK)sensitive and lymphokine-activated-killer(LAK)-sensitive target cell lines; (3) reverse-transcriptase/polymerase-chain-reaction (RT-PCR) experiments showed that most TcR V beta genes were expressed both in fresh and in cultured TIL, suggesting that such cell populations were polyclonal; (4) interferon gamma, IL-4, IL-5, tumour necrosis factor (TNF) alpha, IL-8, IL-10 mRNA and, to a lesser extent, IL-2 mRNA were expressed by cultured TIL, as assessed by RT-PCR; the corresponding tumour samples consistently contained TNF alpha, IL-8 and IL-10 mRNA, whereas IL-2 and IFN gamma mRNA were faintly expressed in some NB tumours and IL-4 and IL-5 mRNA were never detected. A total of 90 clones were subsequently raised from IL-2-expanded TIL from six NB patients; 87/90 clones were of T cell lineage with a CD4+ or CD8+ immunophenotype, whereas the 3 remaining clones were of NK cell origin. Upon triggering of the CD3-TcR complex, 64% CD4+ and 77% CD8+ T cell clones killed the murine P815 mastocytoma cell line. Virtually no T cell clone lysed a LAK-sensitive NB cell line whereas 15% CD4+ and 17% CD8+ clones mediated NK-like activity against the K562 cell line. Finally, the patterns of cytokine production by CD4+ clones were roughly consistent with those of a T helper (TH) 1 profile and similar to those observed in CD8+ clones.
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PMID:Functional and molecular characterization of tumour-infiltrating lymphocytes and clones thereof from a major-histocompatibility-complex-negative human tumour: neuroblastoma. 864 Aug 45

Mouse neuroblastoma Neuro-2a cells were examined for the expression of pro-enkephalin mRNA, protein, and Met-enkephalin ([Met]-Enk) peptide. Reverse transcriptase/polymerase chain reaction (RT/PCR) and in situ hybridization demonstrated the presence of pro-enkephalin mRNA in these cells. Immunocytochemistry using an antibody which recognizes pro-enkephalin and high pressure liquid chromatography (HPLC) followed by radioimmunoassay indicated that pro-enkephalin was synthesized in these cells and processed to yield the bioactive pentapeptide, [Met]-Enk. Furthermore, release studies showed that the [Met]-Enk was secreted from these cells with high K+ stimulation. Using double labeling, in situ hybridization combined with immunocytochemistry, we demonstrated that prohormone convertase 2 (PC2) mRNA is colocalized with pro-enkephalin in the same Neuro-2a cells, suggesting that this enzyme may be responsible for processing this precursor. we also showed the presence of vasopressin mRNA and arginine-vasopressin peptide in these cells using in situ hybridization and immunocytochemistry, respectively. Thus, the Neuro-2a cells are a multiple neuropeptide-producing cell line and an excellent model for studying the mechanisms involved in the synthesis, intracellular targeting and processing of endogenous pro-enkephalin and pro-vasopressin, as well as other transfected neuropeptide precursors.
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PMID:The Neuro-2a neuroblastoma cell line expresses [Met]-enkephalin and vasopressin mRNA and peptide. 867 23


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