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Eckwahl MJ, Arnion H, Kharytonchyk S, Zang T, Bieniasz PD, Telesnitsky A, Wolin SL. Analysis of the human immunodeficiency virus-1 RNA packageome. RNA (NEW YORK, N.Y.) 2016; 22:1228-38. [PMID: 27247436 PMCID: PMC4931115 DOI: 10.1261/rna.057299.116] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 05/15/2016] [Indexed: 05/16/2023]
Abstract
All retroviruses package cellular RNAs into virions. Studies of murine leukemia virus (MLV) revealed that the major host cell RNAs encapsidated by this simple retrovirus were LTR retrotransposons and noncoding RNAs (ncRNAs). Several classes of ncRNAs appeared to be packaged by MLV shortly after synthesis, as precursors to tRNAs, small nuclear RNAs, and small nucleolar RNAs were all enriched in virions. To determine the extent to which the human immunodeficiency virus (HIV-1) packages similar RNAs, we used high-throughput sequencing to characterize the RNAs within infectious HIV-1 virions produced in CEM-SS T lymphoblastoid cells. We report that the most abundant cellular RNAs in HIV-1 virions are 7SL RNA and transcripts from numerous divergent and truncated members of the long interspersed element (LINE) and short interspersed element (SINE) families of retrotransposons. We also detected precursors to several tRNAs and small nuclear RNAs as well as transcripts derived from the ribosomal DNA (rDNA) intergenic spacers. We show that packaging of a pre-tRNA requires the nuclear export receptor Exportin 5, indicating that HIV-1 recruits at least some newly made ncRNAs in the cytoplasm. Together, our work identifies the set of RNAs packaged by HIV-1 and reveals that early steps in HIV-1 assembly intersect with host cell ncRNA biogenesis pathways.
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Affiliation(s)
- Matthew J Eckwahl
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06536, USA
| | - Helene Arnion
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06536, USA
| | - Siarhei Kharytonchyk
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Trinity Zang
- Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10016, USA Laboratory of Retrovirology, The Rockefeller University, New York, New York 10016, USA Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10016, USA
| | - Paul D Bieniasz
- Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10016, USA Laboratory of Retrovirology, The Rockefeller University, New York, New York 10016, USA Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10016, USA
| | - Alice Telesnitsky
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Sandra L Wolin
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06536, USA Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, Connecticut 06536, USA Yale Cancer Center, Yale School of Medicine, New Haven, Connecticut 06520, USA
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Tchurikov NA, Fedoseeva DM, Sosin DV, Snezhkina AV, Melnikova NV, Kudryavtseva AV, Kravatsky YV, Kretova OV. Hot spots of DNA double-strand breaks and genomic contacts of human rDNA units are involved in epigenetic regulation. J Mol Cell Biol 2014; 7:366-82. [PMID: 25280477 PMCID: PMC4524424 DOI: 10.1093/jmcb/mju038] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 08/23/2014] [Indexed: 12/25/2022] Open
Abstract
DNA double-strand breaks (DSBs) are involved in many cellular mechanisms, including replication, transcription, and genome rearrangements. The recent observation that hot spots of DSBs in human chromosomes delimit DNA domains that possess coordinately expressed genes suggests a strong relationship between the organization of transcription patterns and hot spots of DSBs. In this study, we performed mapping of hot spots of DSBs in a human 43-kb ribosomal DNA (rDNA) repeated unit. We observed that rDNA units corresponded to the most fragile sites in human chromosomes and that these units possessed at least nine specific regions containing clusters of extremely frequently occurring DSBs, which were located exclusively in non-coding intergenic spacer (IGS) regions. The hot spots of DSBs corresponded to only a specific subset of DNase-hypersensitive sites, and coincided with CTCF, PARP1, and HNRNPA2B1 binding sites, and H3K4me3 marks. Our rDNA-4C data indicate that the regions of IGS containing the hot spots of DSBs often form contacts with specific regions in different chromosomes, including the pericentromeric regions, as well as regions that are characterized by H3K27ac and H3K4me3 marks, CTCF binding sites, ChIA-PET and RIP signals, and high levels of DSBs. The data suggest a strong link between chromosome breakage and several different mechanisms of epigenetic regulation of gene expression.
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Affiliation(s)
- Nickolai A Tchurikov
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Daria M Fedoseeva
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Dmitri V Sosin
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Anastasia V Snezhkina
- Group of Postgenomic Studies, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Nataliya V Melnikova
- Group of Postgenomic Studies, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Anna V Kudryavtseva
- Group of Postgenomic Studies, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Yuri V Kravatsky
- Laboratory of DNA-Protein Interactions, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Olga V Kretova
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
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Popov A, Smirnov E, Kováčik L, Raška O, Hagen G, Stixová L, Raška I. Duration of the first steps of the human rRNA processing. Nucleus 2013; 4:134-41. [PMID: 23412654 DOI: 10.4161/nucl.23985] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Processing of rRNA in mammalian cells includes a series of cleavages of the primary 47S transcript and results in producing three rRNAs: 18S, 28S and 5.8S. The sequence of the main processing events in human cells has been established, but little is yet known about the dynamics of this process, especially the dynamics of its early stages. In the present study, we used real-time PCR to measure levels of pre-rRNA after inhibition of transcription with actinomycin D. Thus we could estimate the half-life time of rRNA transcripts in two human-derived cell lines, HeLa and LEP (human embryonic fibroblasts), as well as in mouse NIH 3T3 cells. The primary transcripts seemed to be more stable in the human than in the murine cells. Remarkably, the graphs in all cases showed more or less pronounced lag phase, which may reflect preparatory events preceding the first cleavage of the pre-rRNA. Additionally, we followed the dynamics of the decay of the 5'ETS fragment which is degraded only after the formation of 41S rRNA. According to our estimates, the corresponding three (or four) steps of the processing in human cells take five to eight minutes.
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Affiliation(s)
- Alexey Popov
- First Faculty of Medicine, Institute of Cellular Biology and Pathology, Charles University in Prague, Prague, Czech Republic
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Németh A, Perez-Fernandez J, Merkl P, Hamperl S, Gerber J, Griesenbeck J, Tschochner H. RNA polymerase I termination: Where is the end? BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:306-17. [PMID: 23092677 DOI: 10.1016/j.bbagrm.2012.10.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/10/2012] [Accepted: 10/17/2012] [Indexed: 01/01/2023]
Abstract
The synthesis of ribosomal RNA (rRNA) precursor molecules by RNA polymerase I (Pol I) terminates with the dissociation of the protein-DNA-RNA ternary complex. Based on in vitro results the mechanism of Pol I termination appeared initially to be rather conserved and simple until this process was more thoroughly re-investigated in vivo. A picture emerged that Pol I termination seems to be connected to co-transcriptional processing, re-initiation of transcription and, possibly, other processes downstream of Pol I transcription units. In this article, our current understanding of the mechanism of Pol I termination and how this process might be implicated in other biological processes in yeast and mammals is summarized and discussed. This article is part of a Special Issue entitled: Transcription by Odd Pols.
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Affiliation(s)
- Attila Németh
- Universität Regensburg, Biochemie-Zentrum Regensburg (BZR), Lehrstuhl Biochemie III, 93053 Regensburg, Germany.
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Auriemma LB, Shah S, Linden LM, Henriksen MA. Knockdown of menin affects pre-mRNA processing and promoter fidelity at the interferon-gamma inducible IRF1 gene. Epigenetics Chromatin 2012; 5:2. [PMID: 22240255 PMCID: PMC3271985 DOI: 10.1186/1756-8935-5-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 01/12/2012] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The tumor suppressor menin (MEN1) is mutated in the inherited disease multiple endocrine neoplasia type I, and has several documented cellular roles, including the activation and repression of transcription effected by several transcription factors. As an activator, MEN1 is a component of the Set1-like mixed lineage leukemia (MLL) MLL1/MLL2 methyltransferase complex that methylates histone H3 lysine 4 (H3K4). MEN1 is localized to the signal transducer and activator of transcription 1 (STAT1)-dependent gene, interferon regulatory factor 1 (IRF1), and is further recruited when IRF1 transcription is triggered by interferon-γ signaling. RESULTS RNAi-mediated knockdown of MEN1 alters the H3K4 dimethylation and H3 acetylation profiles, and the localization of histone deacetylase 3, at IRF1. While MEN1 knockdown does not impact the rate of transcription, IRF1 heteronuclear transcripts become enriched in MEN1-depleted cells. The processed mRNA and translated protein product are concomitantly reduced, and the antiviral state is attenuated. Additionally, the transcription start site at the IRF1 promoter is disrupted in the MEN1-depleted cells. The H3K4 demethylase, lysine specific demethylase 1, is also associated with IRF1, and its inhibition alters H3K4 methylation and disrupts the transcription start site as well. CONCLUSIONS Taken together, the data indicate that MEN1 contributes to STAT1-activated gene expression in a novel manner that includes defining the transcription start site and RNA processing.
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Affiliation(s)
- Lauren B Auriemma
- Department of Biology, The University of Virginia, 485 McCormick Road, Charlottesville, VA 22903, USA.
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Wang B, Gao C, Ponder KP. C/EBPbeta contributes to hepatocyte growth factor-induced replication of rodent hepatocytes. J Hepatol 2005; 43:294-302. [PMID: 15922473 DOI: 10.1016/j.jhep.2005.02.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 02/03/2005] [Accepted: 02/16/2005] [Indexed: 01/12/2023]
Abstract
BACKGROUND/AIMS Hepatocyte replication can be induced in vivo by hepatocyte growth factor (HGF), which might be used for gene therapy or to promote liver regeneration. However, the biochemical steps critical for this process are not clear. C/EBPbeta and C/EBPalpha are liver-enriched transcription factors that induce and inhibit hepatocyte replication, respectively. Because of their role in hepatocyte replication, this study examined the effect of HGF upon C/EBP proteins in vivo. METHODS Rats were treated with HGF, and the effect upon C/EBPs was evaluated in liver extracts. Normal or C/EBPbeta-deficient mice were treated with HGF, and the effect upon hepatocyte replication was determined. RESULTS HGF had no effect in rat liver upon C/EBPalpha or C/EBPbeta mRNA, nuclear protein, or nuclear DNA binding activity. However, HGF increased phosphorylated p90-RSK and ERK to 18- and 3-fold normal, respectively. These kinases phosphorylate C/EBPbeta and increase its transcriptional activity. The percentage of hepatocytes that replicated in C/EBPbeta-deficient mice after HGF administration was only 1.1%, which was lower than the value of 6.6% for hepatocytes from HGF-treated normal mice (P=0.005). CONCLUSIONS C/EBPbeta contributes to the induction of hepatocyte replication in response to HGF in rodents, which is likely due to post-translational modifications.
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Affiliation(s)
- Bin Wang
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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Hoeger H, Labudova O, Mosgoeller W, Herrera-Marschitz M, Fuerst G, Kitzmüller E, Lubec B. Deficient transcription of subunit RPA 40 of RNA polymerase I and III in heart of rats with neonatal asphyxia. Life Sci 1998; 62:275-82. [PMID: 9450498 DOI: 10.1016/s0024-3205(97)01108-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
RNA polymerases transcribe nuclear genes for ribosomal RNA thus representing ribosomal biogenesis. RNA polymerase I transcribes class I genes, coding for large ribosomal RNA and is located in the nucleolus. RNA polymerase III transcribes class III genes, those that encode a number of small ribosomal RNA molecules. Both RNA polymerases form ribosomal biogenesis in a concerted action and have a common subunit, RPA40, essential for function and integrity. The aim of our study was to study the influence of hypoxia/asphyxia on transcription of this subunit as deterioration of ribosomal biogenesis may not be compatible with life. To test this hypothesis we used a nonsophisticated model of neonatal asphyxia. Rat pups were exposed to various asphyctic periods up to twenty minutes and heart tissue was taken for the evaluation of mRNA RPA40 levels, pH measurements and histological evaluation of the nucleolus by silver staining. mRNA RPA40 levels gradually decreased with the length of the asphyctic period paralleling the decrease of pH. Silver staining was remarkably decreased at the asphyctic period of 20 minutes. Our findings of decreased transcription of this essential RNA polymerase subunit indicate impairment of the ribosomal RNA synthetizing machinery and the histological findings suggest its structural relevance. This is the first in vivo observation of deteriorated RNA polymerase in asphyxia/hypoxia.
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Affiliation(s)
- H Hoeger
- University of Vienna, Dpt of Pediatrics, Austria
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Ghoshal K, Jacob ST. Heat shock inhibits pre-rRNA processing at the primary site in vitro and alters the activity of some rRNA binding proteins. J Cell Biochem 1996; 62:506-15. [PMID: 8891896 DOI: 10.1002/(sici)1097-4644(19960915)62:4<506::aid-jcb8>3.0.co;2-q] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effect of heat shock on pre-rRNA processing at the primary site within external transcribed spacer region 1 (ETS1) was studied in S-100 extract derived from mouse lymphosarcoma cells. In vivo labeling with [32P]orthophosphate showed that the synthesis of the rRNA precursor and its processing to 28S and 18S rRNAs were inhibited significantly due to heat shock. The processing activity was reduced by 50% at 1 h and was completely blocked following 2-h exposure of cells at 42 degrees C. Mixing S-100 extracts from the control and heat-treated cells did not affect the processing activity in the control extract, which proves the absence of a nuclease or other inhibitor(s) of processing in the extract from the heat-shocked cells. Heat shock did not affect interaction between pre-rRNA and U3 snoRNA, a prerequisite for the processing at the primary site, but significantly altered RNA-protein interaction. Three polypeptides of 200, 110, and 52 kDa that specifically cross-link to pre-rRNA spanning the primary processing site were inactivated after heat shock. Hyperthermia did not alter 3' end processing of SV40L pre-mRNA.
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Affiliation(s)
- K Ghoshal
- Department of Pharmacology and Molecular Biology, Chicago Medical School, Illinois 60064, USA
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10
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Wu X, Holschen J, Kennedy SC, Ponder KP. Retroviral vector sequences may interact with some internal promoters and influence expression. Hum Gene Ther 1996; 7:159-71. [PMID: 8788167 DOI: 10.1089/hum.1996.7.2-159] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Although retroviral vectors show promise for gene therapy, their expression in animals has been low. An improved understanding of how promoters function from a retroviral vector should facilitate the design of improved vectors. In this study, liver-specific promoters were cloned into a retroviral vector and expression from the retroviral long terminal repeat (LTR) and the internal promoter was analyzed. In addition, oligomerized liver-specific transcription factor binding sites were placed upstream of each promoter in an attempt to increase expression further. Additional oligomerized binding sites only increased expression slightly or inhibited expression in hepatoma cells, suggesting that this is not an effective way to increase expression from a retroviral vector. Unexpectedly, the liver-specific albumin promoter was expressed at high levels from a retroviral vector in fibroblasts, suggesting that retroviral elements functioned as an enhancer. Furthermore, the addition of HNF-4 binding sites adjacent to the albumin promoter inhibited both the LTR and albumin promoter in fibroblasts, an effect that was probably mediated by inhibitory proteins present in nonhepatic cells that can bind to HNF-4 sites. These results suggest that both positive and negative influences can be transmitted between the LTR and the albumin promoter. In contrast, the liver-specific human alpha 1-antitrypsin promoter did not appear to interact with the LTR by either of these criteria. Retroviral vectors have sequences that may inhibit expression of the LTR and some internal promoters in vivo. We hypothesize that internal promoters that do not interact with the LTR in tissue culture will be resistant to inhibitory effects of retroviral sequences in vivo.
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Affiliation(s)
- X Wu
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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11
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Liu SM, Carpenter G. Differential heat stress stability of epidermal growth factor receptor and erbB-2 receptor tyrosine kinase activities. J Cell Physiol 1993; 157:237-42. [PMID: 7901224 DOI: 10.1002/jcp.1041570205] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The epidermal growth factor (EGF) and erbB-2 receptors are structurally related membrane-bound tyrosine kinases. While these proteins exhibit close sequence homology, 50% overall and 80% in the tyrosine kinase domains, they respond very differently to heat stress. In NIH-3T3 or NR6 cells transfected with wild-type EGF-R and incubated at 37 degrees C or heat shocked at 46 degrees C, EGF binds to its receptor and stimulates receptor autophosphorylation to equivalent extents. At 46 degrees C, however, the basal tyrosine kinase activity of the wild-type erbB-2 receptor is rapidly lost. When cells containing chimeric receptors composed of the EGF-R extracellular domain and intracellular domain of erbB-2 were heat stressed, 125I-EGF bound to the receptors, but did not stimulate receptor autophosphorylation. The decline in EGF-stimulated chimeric erbB-2 receptor autophosphorylation is dependent on the length of heat shock, with nearly 100% of the kinase activity lost after 60 min at 46 degrees C. The loss of chimeric receptor erbB-2 kinase activity is not due to degradation of receptor protein, nor is it attributable to a specific transmembrane domain from either the EGF or erbB-2 receptors. Sensitivity of erbB-2 to heat stress is also not a result of denaturation of this receptor's carboxy-terminal domain. Insertion of the erbB-2 tyrosine kinase domain into the EGF-R confers heat stress sensitivity to the resultant chimeric receptor. Thus, although the EGF-R and erbB-2 kinase domains show a high degree of homology, the secondary/tertiary structures of these domains would seem to be stabilized in distinct manners.
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Affiliation(s)
- S M Liu
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
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Glibetic M, Larson DE, Rothblum LI, Sells BH. Dexamethasone stimulates rRNA gene transcription in rat myoblasts. Mol Cell Endocrinol 1993; 94:243-52. [PMID: 8224527 DOI: 10.1016/0303-7207(93)90173-h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The glucocorticoid analogue, dexamethasone, stimulated RNA synthesis more than two-fold in rat L6 myoblasts, without affecting the rate of cell proliferation. Treatment of myoblasts for 24 h with 10(-7) M dexamethasone resulted in a 30% increase in the cellular RNA level. More than a two-fold stimulation of pre-rRNA gene transcription by dexamethasone, as measured in isolated nuclei and by cell-free transcription, was accompanied by a corresponding increase in pre-rRNA levels. Co-incubation of myoblasts with cycloheximide and dexamethasone did not affect the enhanced pre-rRNA gene transcription demonstrating that de novo protein synthesis was unnecessary to manifest the dexamethasone effect on rDNA transcription. Support for this conclusion is provided by the finding that the levels of UBF1 and UBF2, rDNA upstream binding transcription factors, remain unchanged. The glucocorticoid antagonist RU38486 [11 beta-(4-dimethylaminophenyl)17 beta-hydroxy-17 alpha-(prop-1-ynyl)estra- 4,9-dien-3-one] inhibited the dexamethasone-stimulated rRNA gene transcription suggesting that the glucocorticoid receptor is involved in the response mechanism.
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Affiliation(s)
- M Glibetic
- Department of Molecular Biology and Genetics, University of Guelph, Ontario, Canada
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Kalcheva ID, Karagyozov LK, Hadjiolov AA. Transcription of ribosomal DNA intergenic spacer sequences in normal and regenerating rat liver. Biochem Biophys Res Commun 1991; 176:1333-7. [PMID: 2039515 DOI: 10.1016/0006-291x(91)90432-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In regenerating rat liver both the transcriptional activity of the intergenic spacer rDNA promoter and the steady-state abundance of spacer transcripts are increased about 2-fold, as compared to normal liver. These changes are parallel to the observed 2.5-fold increase in regenerating liver of rRNA gene promotor activity and gene promotor transcripts abundance. These results suggest that both gene and spacer rDNA promotors are subject to common regulatory mechanisms. Our results indicate also that the stability of spacer transcripts in regenerating liver is not significantly altered.
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Affiliation(s)
- I D Kalcheva
- Institute of Cell Biology and Morphology, Bulgarian Academy of Sciences, Sofia
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Raué HA, Planta RJ. Ribosome biogenesis in yeast. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1991; 41:89-129. [PMID: 1882079 DOI: 10.1016/s0079-6603(08)60007-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- H A Raué
- Biochemisch Laboratorium Vrije Universiteit, Amsterdam, The Netherlands
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Ohmori H, Murakami T, Furutani A, Higashi K, Hirano H, Gotoh S, Kuroiwa A, Masui A, Nakamura T, Amalric F. Simultaneous activation of heat shock protein (hsp 70) and nucleolin genes during in vivo and in vitro prereplicative stages of rat hepatocytes. Exp Cell Res 1990; 189:227-32. [PMID: 1695156 DOI: 10.1016/0014-4827(90)90240-b] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Rapidly growing cells usually have high levels of ribosome biogenesis. The sequential expression of protooncogenes during the transition of quiescent hepatocytes to the replicative stage was assumed to be followed by activation of cellular genes related to cell growth such as ribosome biosynthesis. First, the expression of major nucleolar protein (nucleolin or C23) and major heat-shock protein (hsp 70) genes was examined during rat liver regeneration. hsp 70 may function in cell growth and has a characteristic nucleolar location after heat shock. Both nucleolin and hsp 70 mRNA began to increase simultaneously after peaks of c-fos and c-myc, showed a peak 6 h after partial hepatectomy, and declined to the control levels around 20 h. That is, the peaks of nucleolin and hsp 70 mRNA precede the peak of ribosome formation (12-20 h) and DNA replication (24 h). Second, the behavior of nucleolin and hsp 70 mRNA was examined in primary cultured hepatocytes during their G0-G1 transition. Although the amounts of c-myc mRNA reached a plateau around 20 h after the initiation of culture and remained at these levels, DNA synthesis has never been found to start without the addition of EGF and insulin to this system. Both nucleolin and hsp 70 mRNA began to increase at around 20 h (prereplicative stage) and simultaneously decreased in inverse proportion to DNA synthesis induced by these growth factors. Thus, it is possible that the simultaneous enhancement of nucleolin and hsp 70 genes as described above is not merely coincidental, but is important biologically during the transition of quiescent hepatocytes to proliferative cells.
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Affiliation(s)
- H Ohmori
- Department of Biochemistry, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
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