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)

A disease with the characteristics of an erythroblastic leukemia was induced by X-ray irradiation of 300 Rads in C3H mice. The leukemia is transplantable in syngeneic mice by i.v. injection of the spleen cells. The mice show almost pure erythroid cells of various differentiation stages in peripheral blood. The number of total nucleated cells in the peripheral blood increased, but hematocrit and platelet number decreased. Reverse transcriptase activities were measured in spleen and liver of the mice and the data suggested that the leukemia was not induced by retrovirus infection. This leukemia is distinguishable, in this respect, from diseases reported by Friend or Rauscher. The leukemia will offer a good animal model for the studies on non-viral leukemogenesis and disorders of erythropoiesis.
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PMID:Establishment and characterization of a transplantable erythroblastic leukemia in C3H mice. 245 36

Specific roles of manganese (Mn) and magnesium (Mg) on the activities of DNA-dependent RNA polymerases I and II isolated from rabbit bone marrow erythroid cell nuclei were investigated. Three main polymerases were separated from the cell nuclei. When RNA polymerase I and Mg were added to the RNA synthesis assay mixture containing erythroid cell DNA as template, RNA transcription activity was highest, but when Mg was replaced with Mn, denatured calf thymus DNA formed a better template than erythroid cell DNA. In contrast, nucleoplasmic DNA from erythroid cell and liver DNA were the best templates to stimulate RNA transcription when RNA polymerase II and Mn were added to the assay mixture. However, if Mn was replaced with Mg, RNA synthesis activity was drastically reduced when the template was nucleoplasmic DNA of erythroid cell. RNA polymerase I and Mg synthesized GC rich RNA, whereas RNA polymerase II and Mn synthesized AU rich RNA. Sedimentation analysis showed that the molecular weights of the RNA produced by polymerase I were larger when the enzyme was activated with Mg than with Mn, whereas those of the RNA produced by polymerase II were larger with Mn than with Mg. Furthermore, RNA produced by polymerase I and Mg using chromatin as a template hybridized better with nucleolar DNA than with nucleoplasmic DNA, whereas that produced by polymerase II and Mn hybridized better with nucleoplasmic DNA than with nucleolar DNA. These results suggest that RNA synthesis is dependent on the activity of specific RNA polymerases and the presence of specific divalent cations and templates, and that the cofactor and template for RNA polymerase I are, respectively, Mg and the nucleolar DNA of cell nuclei, whereas those for RNA polymerase II are Mn and nucleoplasmic DNA.
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PMID:Specific role of manganese and magnesium on RNA synthesis in rabbit bone marrow erythroid cell nuclei. 248 49

The complete nucleotide sequence of the coding region of the chicken carbonic anhydrase II (CA II) gene has been determined from clones isolated from a chicken genomic library. The sequence of a nearly full length chicken CA II cDNA clone has also been obtained. The gene is approximately 17 kilobase pairs (kb) in size and codes for a protein that is comprised of 259 amino acid residues. The 5' flanking region contains consensus sequences commonly associated with eucaryotic genes transcribed by RNA polymerase II. Six introns ranging in size from 0.3 to 10.2 kb interrupt the gene. The number of introns as well as five of the six intron locations are conserved between the chicken and mouse CA II genes. The site of the fourth intron is shifted by 14 base pairs further 3' in the chicken and thus falls between codons 147 and 148 rather than within codon 143 as in the mouse gene. Measurements of CA II RNA levels in various cell types suggest that CA II RNA increases in parallel with globin RNA during erythropoiesis and exists only at low levels, if at all, in non-erythroid cells.
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PMID:The chicken carbonic anhydrase II gene: evidence for a recent shift in intron position. 302 91

The production of tRNA(iMet) during Friend cell erythroid differentiation has been studied. In vitro measurements of total nuclear RNA synthesis in nuclei isolated from Friend cells at different stages of differentiation show the total RNA synthesis increases 1.5-fold at day 1 of induction and then decreases through days 2 and 3 to approximately 75% of its rate of synthesis in the nuclei of uninduced cells. The synthesis of RNA polymerase III transcripts undergoes a similar fluctuation through day 2 of induction, but increases again at day 3. The specific synthesis of tRNA(iMet) was measured by hybridization of labelled nuclear RNA to a tRNA(iMet) gene probe. During erythroid differentiation the percentage of nuclear RNA represented by tRNA(iMet) remains constant (0.065%), so that the absolute synthesis of tRNA(iMet) fluctuates during differentiation, in the fluctuations in the synthesis of total nuclear RNA. The relative synthesis of tRNA(iMet) in vivo was studied by labelling cells with 32Pi, isolating the resulting radioactive tRNA--5S RNA population, and hybridizing this population to a tRNA(iMet) gene probe. The ratio of tRNA(iMet)/total tRNA--5S RNA in newly synthesized cytoplasmic RNA remains similar throughout differentiation (averaging 0.0171), implying that the fluctuations observed in the nuclear synthesis of tRNA(iMet) during differentiation probably also occur for the nuclear synthesis of most tRNA and 5S RNA species. Attempts were made to measure the relative steady-state concentration of tRNA(iMet) using both aminoacylation and in vitro end labelling of tRNA followed by hybridization to a tRNA(iMet) gene probe. These two methods gave different results and we discuss the possible pitfalls of using enzymatic methods for quantitating tRNA concentrations in the cell.
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PMID:The measurement of the production of tRNA(iMet) during erythroid differentiation of the Friend erythroleukemia cell. 347 29

We have used affinity chromatography on columns containing immobilized calf thymus RNA polymerase II to isolate three phosphoproteins (RAP72, RAP38, and RAP30) that bind directly to RNA polymerase II. All could be isolated from cell nuclei, and all three could be detected in mouse and human tissue culture cell lines, but only RAP38 and RAP30 have so far been isolated from calf thymus. RAP38 stimulates nonspecific transcription of native DNA templates by RNA polymerase II in the presence of Mn2+; it appears to be similar or identical to SII, a previously identified RNA polymerase II stimulatory factor (Nakanishi, Y., Mitsuhashi, Y., Sekimizu, K., Yokoi, H., Tanaka, Y., Horikoshi, M., and Natori, S. (1981) FEBS Lett. 130, 69-72). Unlike RAP38, RAP72 and RAP30 do not affect nonspecific transcription by RNA polymerase II. However, RAP30 may have a role in regulating some alterations of transcription that accompany cellular differentiation; RAP30 is partially dephosphorylated when murine erythroleukemia cells are induced with dimethyl sulfoxide to undergo terminal erythroid differentiation. We suggest that phosphate groups in RNA polymerase II-binding proteins may regulate transcription by modulating the interaction of RNA polymerase II with other regulatory proteins that possess sequence recognition specificity.
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PMID:Isolation of three proteins that bind to mammalian RNA polymerase II. 386 May 4

We have investigated low abundance RNAs transcribed in vitro and in vivo from the human beta-globin gene. These RNAs contain globin mRNA sequences covalently linked to sequences transcribed from the 5' flanking region between -235 and the mRNA cap site (+1). Their synthesis in vitro is sensitive to high (100 micrograms/ml) levels of alpha-amanitin but not to low (2 micrograms/ml) levels, and one region of the DNA template bordering their 5' termini is similar to a small segment of Alu repetitive DNA and to the RNA polymerase III promoter consensus sequence. Therefore, these RNAs are transcribed by RNA polymerase III but extend into the mRNA-coding region that is usually transcribed by polymerase II. The polymerase III transcripts are polyadenylated and are probably spliced. Their presence in bone marrow cells and peripheral blood reticulocytes implies that they play some role in the erythroid cell.
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PMID:Human beta-globin promoter and coding sequences transcribed by RNA polymerase III. 619 93

Accurate initiation of transcription in vitro requires, in addition to RNA polymerase II, factors present in soluble extracts of cultured cells. We have developed transcription system in vitro, which permits us to visualize the transcription-initiation complexes on a mouse beta globin restricted fragment from a recombinant beta globin bacteriophage DNA. Using the lambda fragments as internal controls this system has allowed us to assess the specificity of transcription with RNA polymerase II. Comparing extracts from cells and tissues expressing the globin genes (Friend cells, spleen and blood from phenylhydrazine-induced anemic mice) with those which do not (thymus, liver, PCC3 cells), we observed that specific initiation of transcription on the beta globin gene occurs only with soluble extracts from erythroid tissues. This tissue-specific transcription is partially sensitive to alpha-amanitin and occurs at the 5' end of the globin gene.
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PMID:Tissue-specific formation of transcription-initiation complexes at the 5' end of the mouse beta major globin gene. 688 56

Hematopoietic acetylcholinesterase (ACHE) gene expression and its implication for development were studied by in vivo administration to mice of an antisense phosphorothioate oligonucleotide targetted toward ACHE (AS-ACHE). Hematopoietic alterations were observed by differential cell counts and ACHE mRNA levels determined by quantified RNA polymerase chain reaction (RNA-PCR) and in situ hybridization analyses. In control mice, injected with phosphate-buffered saline and untreated, ACHE mRNA labeling with ACHE [35S]cRNA was about 10-fold higher on megakaryocytes (MK) compared with all other bone marrow cells and increased by 20-fold during MK development, similar to reports for MK actin mRNA. Drastic reductions occurred in the bone marrow lymphocyte and erythroid fractions 12 days following intraperitoneal injection of AS-ACHE (5 micrograms/g weight) into groups of four mice. RNA-PCR revealed over 1000-fold decreases in ACHE mRNA levels in lymph nodes and bone marrow at this time, while actin mRNA levels dropped by 10 and 100-fold in lymph nodes and bone marrow of AS-ACHE treated mice compared with controls. In view of the developmental increase in MK actin, this suggested arrest in MK development as well. By 20 days postinjection, bone marrow actin mRNA was fully restored and the sensitive in situ hybridization technique revealed that ACHE mRNA levels were also restored and reached levels only 2-3-fold lower than in controls in all bone marrow cells of AS-ACHE treated mice. Moreover, lymphocytes and erythroid cells repopulated to levels 25% above normal, and promegakaryocyte and mature MK fractions of the total MK were 3 and 2-fold higher, respectively, than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Antisense inhibition of acetylcholinesterase gene expression causes transient hematopoietic alterations in vivo. 758 68

Four variant AE1 anion exchangers with predicted molecular masses of approximately 99, approximately 102, approximately 104, and approximately 108 kDa are expressed in chicken erythroid cells. These variant polypeptides differ in sequence only at the N terminus of their cytoplasmic domains. Molecular analyses have shown that transcripts derived from both of the erythroid-specific promoters, P1 and P2, encode all four of these AE1 anion exchanger variants. However, quantitative RNase protection analyses have shown that the transcripts derived from the P1 promoter are much more prevalent than those derived from the P2 promoter. Reverse transcriptase polymerase chain reaction studies have indicated that the extensive diversity in the transcripts derived from the AE1 gene occurs both in primitive and definitive lineage erythroid cells. Transient transfection analyses using human erythroleukemia cells have investigated the functional significance of the alternative sequences at the N terminus of these variant exchangers. These studies have shown that the erythroid AE1 variants are sorted to different membrane compartments in these cells. The approximately 99- and approximately 102-kDa variants are primarily sorted to the plasma membrane, whereas the approximately 108-kDa variant is retained in a perinuclear compartment. These results suggest that the alternative N-terminal cytoplasmic sequences of these polypeptides may serve as signals to direct these variant transporters to different membrane compartments within cells.
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PMID:Four variant chicken erythroid AE1 anion exchangers. Role of the alternative N-terminal sequences in intracellular targeting in transfected human erythroleukemia cells. 764 85

A receptor tyrosine kinase (RTK), TIE (tyrosine kinase that contains immunoglobulin-like loops and epidermal growth factor [EGF] homology domains), is expressed in vascular endothelial and hematopoietic cells. We generated monoclonal antibodies (MoAbs) against the extracellular domain of TIE and a polyclonal antibody against the TIE carboxyterminus and used them to analyze expression of TIE in hematopoietic cells. Western blotting detected two forms of TIE protein with a molecular mass of 135 and 130 kD in hematopoietic and endothelial cells. Northern blotting analysis revealed that TIE was expressed preferentially in undifferentiated cell lines, especially when megakaryocytic, but not erythroid differentiation was induced. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that TIE was predominantly expressed in the human hematopoietic progenitor fraction, CD34+ cells. Fluorescence-activated cell sorting (FACS) showed that 42% of CD34+ and 17% of KIT-positive (KIT+) cells were TIE-positive (TIE+). The majority (81%) of the primitive hematopoietic stem cells, CD34+CD38- cells, were TIE+. Assays of progenitor cells and long-term culture-initiating cells (LTC-IC) showed that the TIE+ fraction contained more primitive cells than the TIE- fraction. Some TIE+ cells were in the CD34- fraction, which were CD19+ and CD20+ (B cells). These findings indicate that TIE has a unique spectrum of expression in primitive hematopoietic stem cells and B cells. Although its ligand has not been identified, TIE and its ligand may establish a novel regulatory pathway not only in early hematopoiesis, but also in the differentiation and/or proliferation of B cells.
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PMID:Predominant expression of a receptor tyrosine kinase, TIE, in hematopoietic stem cells and B cells. 854 81


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