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 set of four RNA hairpin helices has been prepared by in vitro transcription with T7 RNA polymerase. The hairpins all contain the same nine base pair helix, but with an extra A, C, or U residue forming a bulge at one position; the fourth hairpin is a perfect helix with no bulge. The helix with a bulged A duplicates six base pairs of a helix in the 16S rRNA known to have an unusually high affinity for ethidium bromide [J. M. Kean, S. A. White, and D. E. Draper, Biochemistry 24, 5062 (1985)]. Binding and chemical cleavage studies with ethidium or the reagent methidiumpropylEDTA-Fe(II) [MPE-Fe(II)] showed that the sequence CpG is a preferred intercalation site whether or not a bulge is present; all three bulged bases enhance intercalation at the CpG sequence by an order of magnitude; and intercalation in a bulged helix results in a concerted conformational change involving the entire helix backbone, again dependent on the presence of a bulge but independent of the particular base. These results suggest that an extra sugar-phosphate residue in an RNA helix backbone has a dramatic effect on the ability of the RNA to adopt new conformations. This effect could be an important reason for the conservation of bulges at certain positions in ribosomal and other RNAs.
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PMID:Single base bulges in small RNA hairpins enhance ethidium binding and promote an allosteric transition. 243 51

We have mapped the distribution of glucocorticoid receptor (GR) mRNA in the male adult rat brain using T7 RNA polymerase transcripts of a 1155 base pair rat GR cDNA clone comprising the coding region for amino acids 140-525. Strong expression of GR mRNA was found in the neurons of the CA1 and CA2 fields of the hippocampus and in the paraventricular and periventricular hypothalamic nuclei. Moderate to strong hybridization was found in the dorsal thalamic nuclei, layers II and VI of the cerebral cortex, the anterior olfactory nucleus and primary olfactory cortex, the hypothalamic mammillary nuclei, the subthalamus, and the granule and mitral cells of the olfactory bulb. Weak to moderate hybridization was found in many other regions of the tel- and diencephalon. Mes- and rhomboencephalic neurons displayed very low levels of GR mRNA relative to the levels observed in the tel- and diencephalon. In the cerebellum, moderate to strong levels of mRNA were detected in the granule and Purkinje cell layers with very low levels elsewhere. Nonneuronal brain elements, such as glial cells, the pia mater, and the choroid plexus, were found to express low to moderate amounts of GR mRNA. These results confirm and extend mapping studies of steroid receptors in the brain using radiolabeled steroids or monoclonal antibodies against rat liver GR and demonstrate that the relative distribution of GR protein in different brain nuclei reflects differences in GR mRNA levels. The rat GR cDNA clone is also shown to provide suitable probes for mapping GR gene expression in the mouse brain.
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PMID:In situ hybridization mapping of glucocorticoid receptor messenger ribonucleic acid in rat brain. 274 54

The interactions of T7 RNA polymerase with T7 late promoters were studied by using quantitative footprinting with methidiumpropyl-EDTA X Fe(II) [MPE-Fe(II)] as the DNA cleaving agent. Class II and class III T7 promoters have a highly conserved 23 base pair sequence from -17 to +6. Among class III promoters the -22 to -18 region is also highly conserved. For a class II promoter, T7 RNA polymerase protects the -17 to -4 region from MPE-Fe(II) cleavage; when GTP is present, protection extends from -17 to +5 (noncoding strand). For a class III promoter, protection extends from -20 to -4 and in the presence of GTP from -20 to +5 (noncoding strand). The protected regions for the coding strands of both promoters were nearly identical with that seen for the noncoding strands. The binding constant for the class III promoter is (4 +/- 1.5) X 10(7) M-1 and in the presence of GTP increases to (10 +/- 1.7) X 10(7) M-1. These binding constants are about 1000 and 200 times greater, respectively, than values reported previously [Ikeda, R. A., & Richardson, C. C. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 3614-3618]. The differences in binding constants are probably due to tRNA and high salt used in those earlier experiments. Both tRNA and high salt (greater than 50 mM NaCl and greater than 10 mM MgCl2) inhibit the binding of the polymerase to the promoter. Optimal binding conditions occur at 2-5 mM MgCl2 and 0-10 mM NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interactions of T7 RNA polymerase with T7 late promoters measured by footprinting with methidiumpropyl-EDTA-iron(II). 303 3

Karyotypic detection of chromosomal 16 abnormalities classically associated with AML M4Eo can be difficult. Characterization of the two genes involved in the inv(16)(p13q22), CBF beta and MYH11, has allowed the detection of fusion transcripts by reverse-transcriptase polymerase chain reaction (RT-PCR). We have analyzed CBF beta-MYH11 fusion transcripts by RT-PCR in myelomonocytic leukemias, with or without eosinophilia, to determine whether their presence correlates with morphology. Fifty-three cases (11 AML M4Eo; 1 AML M4 with atypical abnormal eosinophils (AML M4 "Eo"); 29 AML M4; 8 AML M5; 3 CMML; and 1 AML M2 with eosinophilia) were analyzed. All 11 typical AML M4Eo were CBF beta-MYH11 positive. The single case of AML M4 with distinctive eosinophil abnormalities was negative by karyotype, RT-PCR and fluorescent in situ hybridization (FISH). Three of 29 (10%) AML M4 without abnormal eosinophils were CBF beta-MYH11 positive, 1 of which did not show any apparent chromosome 16 abnormalities by classical metaphase analysis (2 not tested). Both cases tested also showed MYH11 genomic rearrangement. None of the other leukemias were RT-PCR positive. Follow-up of three patient showed residual positivity in apparent complete remission. These data show that CBF beta-MYH11 fusion transcripts occur not only in the vast majority of typical AML M4Eo, but also in approximately 10% of AML M4 without eosinophilic abnormalities, a much higher incidence than the sporadic reports of chromosome 16 abnormalities in AML M4 would suggest. Taken together with the detection of CBF beta-MYH11 transcripts in the absence of apparent chromosome 16 abnormalities by classical banding techniques, these data show that additional screening by either RT-PCR or FISH should be performed in all AML M4, regardless of morphologic features, to allow accurate evaluation of the prognostic importance of this fusion transcript.
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PMID:Detection of the chromosome 16 CBF beta-MYH11 fusion transcript in myelomonocytic leukemias. 785 61

Acute myelomonocytic leukemia with bone marrow eosinophilia (AML-M4Eo in the French-American-British FAB] classification) is frequently associated with pericentric inversion of chromosome 16, inv(16)(p13q22). Recently, the molecular cloning of teh breakpoints has led to the identification of the two fused genes, CBFB on 16q and MYH11 on 16p. We have analyzed 24 patients with AML-M4Eo at diagnosis and 47 patients with AML of other FAB subtypes, by a reverse-transcriptase polymerase chain reaction (RT-PCR) assay for the CBFB/MYH11 fusion mRNAs. Three types of fusion mRNAs were detected in 22 samples of AML-M4Eo (type A, n = 20; type C, n = 1; and type D, n = 1). Among these 22 positive samples, inv(16) was found in the 20 cytogenetically studied cases. No fusion transcript was detected in two patients with AML-M4Eo and in patients with other types of AML. These results confirm that CBFB/MYH11 transcripts (with a predominant type A form) are present in most cases of inv(16) AML. Moreover, detection of the hybrid transcript is closely associated with the finding of abnormal bone marrow (BM) eosinophils in AML-M4Eo as it is not found in other, FAB subtypes of AML, including AML-M4. To assess the presence of type A CBFB/MYH11 fusion transcripts in five AML-M4Eo patients in remission, we designed a sensitive assay combining nested PCR and allele-specific amplification (NPASA). Residual leukemia cells were detected in four patients who were in remission from 4 to 22 months, but not in one patient in long-term remission (5 years). The clinical relevance of persistent CBFB/MYH11 fusion transcripts in remission remains to be established by studying a large prospective series of patients. NPASA provides a useful and sensitive tool for the detection of minimal residual disease in inv(16) AML and, potentially, in other leukemias associated with translocations that result in a predominant fusion transcript.
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PMID:Detection of minimal residual disease in acute myelomonocytic leukemia with abnormal marrow eosinophils by nested polymerase chain reaction with allele specific amplification. 791 48

This report describes a patient presenting with acute myeloid leukaemia (AML-FAB classification M2). Phenotypic markers were positive for cells of the myeloid lineage, but negative for monocyte/macrophage, megakaryocyte, and T-cell lineages. The occasional blast was positive for CALLA. All blasts carried the Philadelphia chromosome (Ph+), with 20% also harbouring a monosomy 7 (a cytogenetic marker for AML). Reverse transcriptase polymerase chain reaction (RT-PCR) analysis revealed the presence of two BCR/Abl mRNA transcripts; b2a2, the CML-type and E1a2, the ALL-type. Immunoglobulin (Ig) gene analysis demonstrated the presence of a small population of cells containing rearranged Ig genes. After a short remission, the patient relapsed. At relapse the leukaemia had undergone a major phenotypic switch from AML to ALL, with blasts bearing B-cell markers. Ig gene analysis confirmed a monoclonal population of B-cells. The Ph+ persisted, but the monosomy 7 had disappeared. The same two BCR/Abl mRNA transcripts were found at relapse as at presentation. To our knowledge, this is the first report of an AML simultaneously expressing BCR/Abl transcripts from both the minor and major BCR. The possible mechanisms of this dual expression are discussed.
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PMID:A Ph+ acute myeloid leukaemia expressing both CML-type and ALL-type BCR/ABL mRNA transcripts. 795 Sep 25

Interleukin-11 is a stromal cells derived cytokine which stimulates the proliferation of primitive haemopoietic progenitor cells. For this paper we have studied the constitutive expression of IL-11 mRNA in a panel of wellknown leukaemic cell lines and samples from AML patients at diagnosis. Moreover, the same cellular populations were evaluated for their proliferative response to recombinant-human-(r-hu). IL-11 alone and combined with r-hu-IL-3, granulocyte-macrophage colony stimulating factor (GM-CSF) and stem cell factor (SCF, c-kit ligand). The colony-forming ability of HL60, K562, KG1 cells and eight fresh AML cell populations was assessed by a clonogenic assay in methylcellulose. In eight additional AML cases the number of S-phase leukaemic cells induced by IL-11 was determined by the bromodeoxyuridine (BRDU) incorporation assay after 3d of liquid culture. IL-11, as single cytokine, did not stimulate the colony formation of the three myeloid cell lines under serum-containing and serum-free conditions. In contrast, the proliferation of the leukaemic cells in response to IL-3, GM-CSF and SCF was enhanced by co-incubation with IL-11, and this effect was reversed in blocking experiments by the anti-IL-11 Moab. When tested on primary AML samples, IL-11 alone showed little, if any, proliferative activity. However, it increased the IL-3-dependent blast colony formation in eight out of eight cases and GM-CSF in seven cases. IL-11 also augmented synergistically the number of CFU-L stimulated by SCF in seven cases. A combination of three factors (IL-11, SCF and IL-3) yielded optimal colony formation. The BRDU studies showed the significant increase of AML cells in S-phase when IL-11 was combined with SCF, whereas the two CSF had no activity on their own. Positive interaction was also observed when IL-11 was added to IL-3 supplemented cultures in five out of eight cases tested. Reverse transcriptase-polymerase chain reaction amplification (RT-PCR) demonstrated the constitutive expression of IL-11 mRNA in all the cell lines and 11/12 AML samples studied at diagnosis. These results indicate that IL-11 is expressed in leukaemic myeloid cells and that their proliferation is regulated by the cytokine which acts as a synergistic factor.
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PMID:Interleukin-11 (IL-11) acts as a synergistic factor for the proliferation of human myeloid leukaemic cells. 854 68

Pericentric inversion of chromosome 16 [inv(16)(p13q22)] is seen in patients with acute myelomonocytic leukemia with bone marrow eosinophilia. This inversion juxtaposes the MYH11 gene on p13 and the CBFB gene on q22, resulting in the formation of a chimeric mRNA transcript. We describe a patient with acute myelogenous leukemia (M1), with del(16)(q22), who expressed the chimeric transcript. Reverse transcriptase polymerase chain reaction and the sequencing of its product showed fusion of 5'CBFB at position 495 to 3'MYH11 at position 1201. To our knowledge, this is the first report of an AML (M1) case with del(16) and CBFB/MYH11 rearrangement.
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PMID:CBFB/MYH11 fusion transcripts in a case of acute myelogenous leukemia (M1) with partial deletion of the long arm of chromosome 16. 873 92

Receptor tyrosine kinases (RTK) play an important role in the signal transduction of normal and malignant cells. There are different families of RTKs which are mainly characterized by differences in the ligang-binding extracellular domains. Axl (or UFO/Ark) is the first member of a new class of RTK with two fibronectin type III domains and two immunoglobulin-like domains present at the extracellular domain. The axl-gene has been isolated by means of gene transfection studies using DNA of patients with chronic myelogeneous leukemia. For a previous and the present study, we used a sensitive reverse-transcriptase polymerase chain reaction assay to detect axl's mRNA in cells from normal and malignant hematopoietic tissue. Axl's mRNA expression was mainly detected in myelo-monocytic cells, whereas much weaker transcription was seen in lymphatic cells and in lymphatic leukemias. In normal bone marrow, axl was heavily transcribed in marrow stromal cells. Further, we analysed Axl protein expression using monoclonal antibody M50 in peripheral stem cell harvests; in most harvests, no co-expression of CD34 and Axl was detected. However, in one patient with AML in complete remission, Axl was co-expressed on 80% of the CD34-positive population. These data show that axl is preferentially expressed in monocytes and stromal cells. Furthermore, a fraction of CD34-positive progenitor cells may express Axl. The exact mechanism for transformation of myeloid progenitor cells through Axl, however, remains to be determined.
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PMID:Recent progress on the role of Axl, a receptor tyrosine kinase, in malignant transformation of myeloid leukemias. 913 Jun 17

The AML/CBFalpha runt transcription factors are key regulators of hematopoietic and bone tissue-specific gene expression. These factors contain a 31-amino acid nuclear matrix targeting signal that supports association with the nuclear matrix. We determined that the AML/CBFalpha factors must bind to the nuclear matrix to exert control of transcription. Fusing the nuclear matrix targeting signal to the GAL4 DNA binding domain transactivates a genomically integrated GAL4 responsive reporter gene. These data suggest that AML/CBFalpha must associate with the nuclear matrix to effect transcription. We used fluorescence labeling of epitope-tagged AML-1B (CBFA2) to show it colocalizes with a subset of hyperphosphorylated RNA polymerase II molecules concentrated in foci and linked to the nuclear matrix. This association of AML-1B with RNA polymerase II requires active transcription and a functional DNA binding domain. The nuclear matrix domains that contain AML-1B are distinct from SC35 RNA processing domains. Our results suggest two of the requirements for AML-dependent transcription initiation by RNA polymerase II are association of AML-1B with the nuclear matrix together with specific binding of AML to gene promoters.
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PMID:Intranuclear targeting of AML/CBFalpha regulatory factors to nuclear matrix-associated transcriptional domains. 946 59


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