1
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Pessoa J, Carvalho C. Human RNA Polymerase II Segregates from Genes and Nascent RNA and Transcribes in the Presence of DNA-Bound dCas9. Int J Mol Sci 2024; 25:8411. [PMID: 39125980 PMCID: PMC11312690 DOI: 10.3390/ijms25158411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Revised: 07/21/2024] [Accepted: 07/27/2024] [Indexed: 08/12/2024] Open
Abstract
RNA polymerase II (Pol II) dysfunction is frequently implied in human disease. Understanding its functional mechanism is essential for designing innovative therapeutic strategies. To visualize its supra-molecular interactions with genes and nascent RNA, we generated a human cell line carrying ~335 consecutive copies of a recombinant β-globin gene. Confocal microscopy showed that Pol II was not homogeneously concentrated around these identical gene copies. Moreover, Pol II signals partially overlapped with the genes and their nascent RNA, revealing extensive compartmentalization. Using a cell line carrying a single copy of the β-globin gene, we also tested if the binding of catalytically dead CRISPR-associated system 9 (dCas9) to different gene regions affected Pol II transcriptional activity. We assessed Pol II localization and nascent RNA levels using chromatin immunoprecipitation and droplet digital reverse transcription PCR, respectively. Some enrichment of transcriptionally paused Pol II accumulated in the promoter region was detected in a strand-specific way of gRNA binding, and there was no decrease in nascent RNA levels. Pol II preserved its transcriptional activity in the presence of DNA-bound dCas9. Our findings contribute further insight into the complex mechanism of mRNA transcription in human cells.
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Affiliation(s)
- João Pessoa
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal;
- Department of Medical Sciences and Institute of Biomedicine—iBiMED, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Célia Carvalho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal;
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2
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Wang H, Ma B, Stevens T, Knapp J, Lu J, Prochownik EV. MYC Binding Near Transcriptional End Sites Regulates Basal Gene Expression, Read-Through Transcription and Intragenic Contacts. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.11.603118. [PMID: 39071289 PMCID: PMC11275772 DOI: 10.1101/2024.07.11.603118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The MYC oncoprotein regulates numerous genes involved in cellular processes such as cell cycle and mitochondrial and ribosomal structure and function. This requires heterodimerization with its partner, MAX, and binding to specific promoter and enhancer elements. Here, we show that MYC and MAX also bind near transcriptional end sites (TESs) of over one-sixth of all annotated genes. These interactions are dose-dependent, evolutionarily conserved, stabilize the normally short-lived MYC protein and regulate expression both in concert with and independent of MYC's binding elsewhere. MYC's TES binding occurs in association with other transcription factors, alters the chromatin landscape, increases nuclease susceptibility and can alter transcriptional read-through, particularly in response to certain stresses. MYC-bound TESs can directly contact promoters and may fine-tune gene expression in response to both physiologic and pathologic stimuli. Collectively, these findings support a previously unrecognized role for MYC in regulating transcription and its read-through via direct intragenic contacts between TESs and promoters.
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3
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Kindongo O, Lieb G, Skaggs B, Dusserre Y, Vincenzetti V, Pelet S. Implication of polymerase recycling for nascent transcript quantification by live cell imaging. Yeast 2024; 41:279-294. [PMID: 38389243 DOI: 10.1002/yea.3929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/29/2023] [Accepted: 01/18/2024] [Indexed: 02/24/2024] Open
Abstract
Transcription enables the production of RNA from a DNA template. Due to the highly dynamic nature of transcription, live-cell imaging methods play a crucial role in measuring the kinetics of this process. For instance, transcriptional bursts have been visualized using fluorescent phage-coat proteins that associate tightly with messenger RNA (mRNA) stem loops formed on nascent transcripts. To convert the signal emanating from a transcription site into meaningful estimates of transcription dynamics, the influence of various parameters on the measured signal must be evaluated. Here, the effect of gene length on the intensity of the transcription site focus was analyzed. Intuitively, a longer gene can support a larger number of transcribing polymerases, thus leading to an increase in the measured signal. However, measurements of transcription induced by hyper-osmotic stress responsive promoters display independence from gene length. A mathematical model of the stress-induced transcription process suggests that the formation of gene loops that favor the recycling of polymerase from the terminator to the promoter can explain the observed behavior. One experimentally validated prediction from this model is that the amount of mRNA produced from a short gene should be higher than for a long one as the density of active polymerase on the short gene will be increased by polymerase recycling. Our data suggest that this recycling contributes significantly to the expression output from a gene and that polymerase recycling is modulated by the promoter identity and the cellular state.
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Affiliation(s)
- Olivia Kindongo
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Guillaume Lieb
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Benjamin Skaggs
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Yves Dusserre
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Vincent Vincenzetti
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Serge Pelet
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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4
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Alfonso-Gonzalez C, Hilgers V. (Alternative) transcription start sites as regulators of RNA processing. Trends Cell Biol 2024:S0962-8924(24)00033-3. [PMID: 38531762 DOI: 10.1016/j.tcb.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/28/2024]
Abstract
Alternative transcription start site usage (ATSS) is a widespread regulatory strategy that enables genes to choose between multiple genomic loci for initiating transcription. This mechanism is tightly controlled during development and is often altered in disease states. In this review, we examine the growing evidence highlighting a role for transcription start sites (TSSs) in the regulation of mRNA isoform selection during and after transcription. We discuss how the choice of transcription initiation sites influences RNA processing and the importance of this crosstalk for cell identity and organism function. We also speculate on possible mechanisms underlying the integration of transcriptional and post-transcriptional processes.
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Affiliation(s)
- Carlos Alfonso-Gonzalez
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Faculty of Biology, Albert Ludwigs University, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology (IMPRS- MCB), 79108 Freiburg, Germany
| | - Valérie Hilgers
- Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany.
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5
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The sight of transcription. Nat Cell Biol 2022; 24:284-285. [DOI: 10.1038/s41556-022-00865-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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6
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Leidescher S, Ribisel J, Ullrich S, Feodorova Y, Hildebrand E, Galitsyna A, Bultmann S, Link S, Thanisch K, Mulholland C, Dekker J, Leonhardt H, Mirny L, Solovei I. Spatial organization of transcribed eukaryotic genes. Nat Cell Biol 2022; 24:327-339. [PMID: 35177821 DOI: 10.1038/s41556-022-00847-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 01/10/2022] [Indexed: 12/19/2022]
Abstract
Despite the well-established role of nuclear organization in the regulation of gene expression, little is known about the reverse: how transcription shapes the spatial organization of the genome. Owing to the small sizes of most previously studied genes and the limited resolution of microscopy, the structure and spatial arrangement of a single transcribed gene are still poorly understood. Here we study several long highly expressed genes and demonstrate that they form open-ended transcription loops with polymerases moving along the loops and carrying nascent RNAs. Transcription loops can span across micrometres, resembling lampbrush loops and polytene puffs. The extension and shape of transcription loops suggest their intrinsic stiffness, which we attribute to decoration with multiple voluminous nascent ribonucleoproteins. Our data contradict the model of transcription factories and suggest that although microscopically resolvable transcription loops are specific for long highly expressed genes, the mechanisms underlying their formation could represent a general aspect of eukaryotic transcription.
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Affiliation(s)
- Susanne Leidescher
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Johannes Ribisel
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Simon Ullrich
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Yana Feodorova
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.,Department of Medical Biology, Medical University of Plovdiv; Division of Molecular and Regenerative Medicine, Research Institute at Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Erica Hildebrand
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Sebastian Bultmann
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Stephanie Link
- BioMedizinisches Center, Ludwig-Maximilians University Munich, Planegg-Martinsried, Germany
| | - Katharina Thanisch
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.,Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Christopher Mulholland
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Heinrich Leonhardt
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Leonid Mirny
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Irina Solovei
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.
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7
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Razin SV, Gavrilov AA. Non-coding RNAs in chromatin folding and nuclear organization. Cell Mol Life Sci 2021; 78:5489-5504. [PMID: 34117518 PMCID: PMC11072467 DOI: 10.1007/s00018-021-03876-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/24/2021] [Accepted: 06/05/2021] [Indexed: 12/19/2022]
Abstract
One of the most intriguing questions facing modern biology concerns how the genome directs the construction of cells, tissues, and whole organisms. It is tempting to suggest that the part of the genome that does not encode proteins contains architectural plans. We are still far from understanding how these plans work at the level of building tissues and the body as a whole. However, the results of recent studies demonstrate that at the cellular level, special non-coding RNAs serve as scaffolds for the construction of various intracellular structures. The term "architectural RNAs" was proposed to designate this subset of non-coding RNAs. In this review, we discuss the role of architectural RNAs in the construction of the cell nucleus and maintenance of the three-dimensional organization of the genome.
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Affiliation(s)
- Sergey V Razin
- Institute of Gene Biology, Russian Academy of Sciences, 119334, Moscow, Russia.
- Faculty of Biology, M. V. Lomonosov Moscow State University, 119234, Moscow, Russia.
| | - Alexey A Gavrilov
- Institute of Gene Biology, Russian Academy of Sciences, 119334, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334, Moscow, Russia
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8
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Liu J, Hansen D, Eck E, Kim YJ, Turner M, Alamos S, Garcia HG. Real-time single-cell characterization of the eukaryotic transcription cycle reveals correlations between RNA initiation, elongation, and cleavage. PLoS Comput Biol 2021; 17:e1008999. [PMID: 34003867 PMCID: PMC8162642 DOI: 10.1371/journal.pcbi.1008999] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 05/28/2021] [Accepted: 04/23/2021] [Indexed: 12/23/2022] Open
Abstract
The eukaryotic transcription cycle consists of three main steps: initiation, elongation, and cleavage of the nascent RNA transcript. Although each of these steps can be regulated as well as coupled with each other, their in vivo dissection has remained challenging because available experimental readouts lack sufficient spatiotemporal resolution to separate the contributions from each of these steps. Here, we describe a novel application of Bayesian inference techniques to simultaneously infer the effective parameters of the transcription cycle in real time and at the single-cell level using a two-color MS2/PP7 reporter gene and the developing fruit fly embryo as a case study. Our method enables detailed investigations into cell-to-cell variability in transcription-cycle parameters as well as single-cell correlations between these parameters. These measurements, combined with theoretical modeling, suggest a substantial variability in the elongation rate of individual RNA polymerase molecules. We further illustrate the power of this technique by uncovering a novel mechanistic connection between RNA polymerase density and nascent RNA cleavage efficiency. Thus, our approach makes it possible to shed light on the regulatory mechanisms in play during each step of the transcription cycle in individual, living cells at high spatiotemporal resolution.
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Affiliation(s)
- Jonathan Liu
- Department of Physics, University of California at Berkeley, Berkeley, California, United States of America
| | - Donald Hansen
- Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, Heidelberg, Germany
| | - Elizabeth Eck
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, California, United States of America
| | - Yang Joon Kim
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, California, United States of America
| | - Meghan Turner
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, California, United States of America
| | - Simon Alamos
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, California, United States of America
| | - Hernan G. Garcia
- Department of Physics, University of California at Berkeley, Berkeley, California, United States of America
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, California, United States of America
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California, United States of America
- Institute for Quantitative Biosciences-QB3, University of California at Berkeley, Berkeley, California, United States of America
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9
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Gavrilov AA, Zharikova AA, Galitsyna AA, Luzhin A, Rubanova NM, Golov AK, Petrova NV, Logacheva M, Kantidze OL, Ulianov SV, Magnitov MD, Mironov AA, Razin SV. Studying RNA-DNA interactome by Red-C identifies noncoding RNAs associated with various chromatin types and reveals transcription dynamics. Nucleic Acids Res 2020; 48:6699-6714. [PMID: 32479626 PMCID: PMC7337940 DOI: 10.1093/nar/gkaa457] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 05/13/2020] [Accepted: 05/18/2020] [Indexed: 12/15/2022] Open
Abstract
Non-coding RNAs (ncRNAs) participate in various biological processes, including regulating transcription and sustaining genome 3D organization. Here, we present a method termed Red-C that exploits proximity ligation to identify contacts with the genome for all RNA molecules present in the nucleus. Using Red-C, we uncovered the RNA-DNA interactome of human K562 cells and identified hundreds of ncRNAs enriched in active or repressed chromatin, including previously undescribed RNAs. Analysis of the RNA-DNA interactome also allowed us to trace the kinetics of messenger RNA production. Our data support the model of co-transcriptional intron splicing, but not the hypothesis of the circularization of actively transcribed genes.
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Affiliation(s)
- Alexey A Gavrilov
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anastasiya A Zharikova
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia
- National Medical Research Center for Preventive Medicine, Ministry of Healthcare of the Russian Federation, Moscow, Russia
| | - Aleksandra A Galitsyna
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia
- Skolkovo Institute of Science and Technology, Skolkovo, Russia
| | - Artem V Luzhin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | | | - Arkadiy K Golov
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Mental Health Research Center, Moscow, Russia
| | | | | | - Omar L Kantidze
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Sergey V Ulianov
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Mikhail D Magnitov
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Andrey A Mironov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia
- Faculty of Computer Science, Higher School of Economics, Moscow, Russia
| | - Sergey V Razin
- To whom correspondence should be addressed. Tel: +7 499 135 3092; Fax: +7 499 135 4105;
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10
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Tamura K. Nuclear pore complex-mediated gene expression in Arabidopsis thaliana. JOURNAL OF PLANT RESEARCH 2020; 133:449-455. [PMID: 32170459 DOI: 10.1007/s10265-020-01177-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 03/08/2020] [Indexed: 05/20/2023]
Abstract
Nuclear pore complexes (NPCs) are large multi-protein complexes that control bidirectional trafficking of macromolecules between the nucleus and cytoplasm. This trafficking is highly regulated and participates in a considerably broader range of cellular activities, including defense responses against pathogens in plants. Recently, NPC is emerging as a platform to physically associate the underlying chromatin with the nuclear periphery, thus regulating chromatin structure and gene expression. For instance, NPC components have been shown to promote the formation of specific genomics loops, which is linked to transcriptional memory for rapid reactivation of genes. With newly developed techniques and tools, our insight in this area has been substantially advanced. This review summarizes recent works on the molecular function of NPC machinery as hubs for transcriptional regulation and compares systems between plant and non-plant organisms.
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Affiliation(s)
- Kentaro Tamura
- Department of Environmental and Life Sciences, University of Shizuoka, Shizuoka, 422-8526, Japan.
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11
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Calvo O. RNA polymerase II phosphorylation and gene looping: new roles for the Rpb4/7 heterodimer in regulating gene expression. Curr Genet 2020; 66:927-937. [PMID: 32508001 DOI: 10.1007/s00294-020-01084-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 12/22/2022]
Abstract
In eukaryotes, cellular RNAs are produced by three nuclear RNA polymerases (RNAPI, II, and III), which are multisubunit complexes. They share structural and functional features, although they are specialized in the synthesis of specific RNAs. RNAPII transcribes the vast majority of cellular RNAs, including mRNAs and a large number of noncoding RNAs. The structure of RNAPII is highly conserved in all eukaryotes, consisting of 12 subunits (Rpb1-12) organized into five structural modules, among which the Rpb4 and Rpb7 subunits form the stalk. Early studies suggested an accessory role for Rpb4, because is required for specific gene transcription pathways. Far from this initial hypothesis, it is now well established that the Rpb4/7 heterodimer plays much wider roles in gene expression regulation. It participates in nuclear and cytosolic processes ranging from transcription to translation and mRNA degradation in a cyclical process. For this reason, Rpb4/7 is considered a coordinator of gene expression. New functions have been added to the list of stalk functions during transcription, which will be reviewed herein: first, a role in the maintenance of proper RNAPII phosphorylation levels, and second, a role in the establishment of a looped gene architecture in actively transcribed genes.
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Affiliation(s)
- Olga Calvo
- Instituto de Biología Funcional y Genómica (IBFG), CSIC-USAL, C/ Zacarías González 2, Salamanca, 37007, España.
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12
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Chowdhary S, Kainth AS, Pincus D, Gross DS. Heat Shock Factor 1 Drives Intergenic Association of Its Target Gene Loci upon Heat Shock. Cell Rep 2020; 26:18-28.e5. [PMID: 30605674 PMCID: PMC6435272 DOI: 10.1016/j.celrep.2018.12.034] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 06/27/2018] [Accepted: 12/07/2018] [Indexed: 12/22/2022] Open
Abstract
Transcriptional induction of heat shock protein (HSP) genes is accompanied by dynamic changes in their 3D structure and spatial organization, yet the molecular basis for these phenomena remains unknown. Using chromosome conformation capture and single-cell imaging, we show that genes transcriptionally activated by Hsf1 specifically interact across chromosomes and coalesce into diffraction-limited intranuclear foci. Genes activated by the alternative stress regulators Msn2/Msn4, in contrast, do not interact among themselves nor with Hsf1 targets. Likewise, constitutively expressed genes, even those interposed between HSP genes, show no detectable interaction. Hsf1 forms discrete subnuclear puncta when stress activated, and these puncta dissolve in concert with transcriptional attenuation, paralleling the kinetics of HSP gene coalescence and dissolution. Nuclear Hsf1 and RNA Pol II are both necessary for intergenic HSP gene interactions, while DNA-bound Hsf1 is necessary and sufficient to drive heterologous gene coalescence. Our findings demonstrate that Hsf1 can dynamically restructure the yeast genome. While gene repositioning is thought to be a general feature of transcription, Chowdhary et al. provide evidence that argues against this concept. The authors demonstrate that Hsf1-regulated genes in Saccharomyces cerevisiae distinctively coalesce into intranuclear foci upon their transcriptional activation, while those activated by alternative transcription factors do not.
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Affiliation(s)
- Surabhi Chowdhary
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
| | - Amoldeep S Kainth
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
| | - David Pincus
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - David S Gross
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA.
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13
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Allepuz-Fuster P, O'Brien MJ, González-Polo N, Pereira B, Dhoondia Z, Ansari A, Calvo O. RNA polymerase II plays an active role in the formation of gene loops through the Rpb4 subunit. Nucleic Acids Res 2019; 47:8975-8987. [PMID: 31304538 PMCID: PMC6753479 DOI: 10.1093/nar/gkz597] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/27/2019] [Accepted: 06/29/2019] [Indexed: 01/19/2023] Open
Abstract
Gene loops are formed by the interaction of initiation and termination factors occupying the distal ends of a gene during transcription. RNAPII is believed to affect gene looping indirectly owing to its essential role in transcription. The results presented here, however, demonstrate a direct role of RNAPII in gene looping through the Rpb4 subunit. 3C analysis revealed that gene looping is abolished in the rpb4Δ mutant. In contrast to the other looping-defective mutants, rpb4Δ cells do not exhibit a transcription termination defect. RPB4 overexpression, however, rescued the transcription termination and gene looping defect of sua7-1, a mutant of TFIIB. Furthermore, RPB4 overexpression rescued the ssu72-2 gene looping defect, while SSU72 overexpression restored the formation of gene loops in rpb4Δ cells. Interestingly, the interaction of TFIIB with Ssu72 is compromised in rpb4Δ cells. These results suggest that the TFIIB-Ssu72 interaction, which is critical for gene loop formation, is facilitated by Rpb4. We propose that Rpb4 is promoting the transfer of RNAPII from the terminator to the promoter for reinitiation of transcription through TFIIB-Ssu72 mediated gene looping.
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Affiliation(s)
| | - Michael J O'Brien
- Department of Biological Science. Wayne State University. Detroit, MI 48202, USA
| | | | - Bianca Pereira
- Department of Biological Science. Wayne State University. Detroit, MI 48202, USA
| | - Zuzer Dhoondia
- Department of Biological Science. Wayne State University. Detroit, MI 48202, USA
| | - Athar Ansari
- Department of Biological Science. Wayne State University. Detroit, MI 48202, USA
| | - Olga Calvo
- Instituto de Biología Funcional y Genómica, CSIC-USAL, Salamanca, Spain
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14
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Wang HLV, Chekanova JA. Novel mRNAs 3' end-associated cis-regulatory elements with epigenomic signatures of mammalian enhancers in the Arabidopsis genome. RNA (NEW YORK, N.Y.) 2019; 25:1242-1258. [PMID: 31311821 PMCID: PMC6800480 DOI: 10.1261/rna.071209.119] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 07/04/2019] [Indexed: 06/10/2023]
Abstract
The precise spatial and temporal control of gene expression requires the coordinated action of genomic cis-regulatory elements (CREs), including transcriptional enhancers. However, our knowledge of enhancers in plants remains rudimentary and only a few plant enhancers have been experimentally defined. Here, we screened the Arabidopsis thaliana genome and identified >1900 unique candidate CREs that carry the genomic signatures of mammalian enhancers. These were termed putative enhancer-like elements (PEs). Nearly all PEs are intragenic and, unexpectedly, most associate with the 3' ends of protein-coding genes. PEs are hotspots for transcription factor binding and harbor motifs resembling cleavage/polyadenylation signals, potentially coupling 3' end processing to the transcriptional regulation of other genes. Hi-C data showed that 24% of PEs are located at regions that can interact intrachromosomally with other protein-coding genes and, surprisingly, many of these target genes interact with PEs through their 3' UTRs. Examination of the genomes of 1135 sequenced Arabidopsis accessions showed that PEs are conserved. Our findings suggest that the identified PEs may serve as transcriptional enhancers and sites for mRNA 3' end processing, and constitute a novel group of CREs in Arabidopsis.
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Affiliation(s)
- Hsiao-Lin V Wang
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Julia A Chekanova
- Mycological Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
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15
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Fernandez-Albert J, Lipinski M, Lopez-Cascales MT, Rowley MJ, Martin-Gonzalez AM, Del Blanco B, Corces VG, Barco A. Immediate and deferred epigenomic signatures of in vivo neuronal activation in mouse hippocampus. Nat Neurosci 2019; 22:1718-1730. [PMID: 31501571 PMCID: PMC6875776 DOI: 10.1038/s41593-019-0476-2] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 07/23/2019] [Indexed: 11/08/2022]
Abstract
Activity-driven transcription plays an important role in many brain processes, including those underlying memory and epilepsy. Here we combine genetic tagging of nuclei and ribosomes with RNA sequencing, chromatin immunoprecipitation with sequencing, assay for transposase-accessible chromatin using sequencing and Hi-C to investigate transcriptional and chromatin changes occurring in mouse hippocampal excitatory neurons at different time points after synchronous activation during seizure and sparse activation by novel context exploration. The transcriptional burst is associated with an increase in chromatin accessibility of activity-regulated genes and enhancers, de novo binding of activity-regulated transcription factors, augmented promoter-enhancer interactions and the formation of gene loops that bring together the transcription start site and transcription termination site of induced genes and may sustain the fast reloading of RNA polymerase complexes. Some chromatin occupancy changes and interactions, particularly those driven by AP1, remain long after neuronal activation and could underlie the changes in neuronal responsiveness and circuit connectivity observed in these neuroplasticity paradigms, perhaps thereby contributing to metaplasticity in the adult brain.
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Affiliation(s)
- Jordi Fernandez-Albert
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain
| | - Michal Lipinski
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain
| | - María T Lopez-Cascales
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain
| | - M Jordan Rowley
- Department of Biology, Emory University, Atlanta, GA, USA
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, USA
| | - Ana M Martin-Gonzalez
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain
- Nencki Institute of Experimental Biology PAS, Warsaw, Poland
| | - Beatriz Del Blanco
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain
| | | | - Angel Barco
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain.
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16
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Pascual-Garcia P, Capelson M. Nuclear pores in genome architecture and enhancer function. Curr Opin Cell Biol 2019; 58:126-133. [PMID: 31063899 DOI: 10.1016/j.ceb.2019.04.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/28/2019] [Accepted: 04/02/2019] [Indexed: 01/28/2023]
Abstract
Nuclear genome architecture relies on interactions between the genome and various nuclear scaffolds. One such a nuclear scaffold is the nuclear pore complex (NPC), which in addition to its nuclear transport function, can interact with underlying chromatin. In particular, NPCs have been recently reported to associate with a number of enhancers and superenhancers in metazoan genomes, and select NPC components have been shown to promote the formation of specific genomic loops. Here, we provide a brief overview of current models of enhancer function, and discuss recent evidence that NPCs bind enhancers and contribute to topological genome organization. We also examine possible models of how gene and enhancer targeting to NPCs may contribute to tissue-specific genome architecture and expression programs, including the possibility that NPCs may promote phase separation of transcriptional compartments.
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Affiliation(s)
- Pau Pascual-Garcia
- Department of Cell and Developmental Biology, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Maya Capelson
- Department of Cell and Developmental Biology, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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17
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Li Z, Jiang D, He Y. FRIGIDA establishes a local chromosomal environment for FLOWERING LOCUS C mRNA production. NATURE PLANTS 2018; 4:836-846. [PMID: 30224662 DOI: 10.1038/s41477-018-0250-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 08/13/2018] [Indexed: 05/08/2023]
Abstract
FRIGIDA (FRI) upregulates the expression of the potent floral repressor FLOWERING LOCUS C (FLC) to confer the winter-annual growth habit in Arabidopsis thaliana: accelerated transition to flowering after prolonged cold exposure (vernalization). Here, we show that FRI, histone acetyltransferases, the histone methyltransferase COMPASS-like and other chromatin modifiers are part of a FRI-containing supercomplex enriched in a region around the FLC transcription start site (TSS) to promote its expression. Several FRI partners are also enriched in a 3' region flanking FLC and, together with FRI, they function to increase the frequency of physical association of the region around TSS with the 3' region and promote the expression of both sense FLC and antisense non-coding RNAs. Our results show that the FRI supercomplex establishes a local chromosomal environment at FLC with active chromatin modifications and topology to promote transcriptional activation, fast elongation and efficient pre-messenger RNA splicing, leading to a high-level production of FLC mRNAs.
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Affiliation(s)
- Zicong Li
- Shanghai Center for Plant Stress Biology & National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Danhua Jiang
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yuehui He
- Shanghai Center for Plant Stress Biology & National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences (CAS), Shanghai, China.
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
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18
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Interferon stimulation creates chromatin marks and establishes transcriptional memory. Proc Natl Acad Sci U S A 2018; 115:E9162-E9171. [PMID: 30201712 DOI: 10.1073/pnas.1720930115] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Epigenetic memory for signal-dependent transcription has remained elusive. So far, the concept of epigenetic memory has been largely limited to cell-autonomous, preprogrammed processes such as development and metabolism. Here we show that IFNβ stimulation creates transcriptional memory in fibroblasts, conferring faster and greater transcription upon restimulation. The memory was inherited through multiple cell divisions and led to improved antiviral protection. Of ∼2,000 IFNβ-stimulated genes (ISGs), about half exhibited memory, which we define as memory ISGs. The rest, designated nonmemory ISGs, did not show memory. Surprisingly, mechanistic analysis showed that IFN memory was not due to enhanced IFN signaling or retention of transcription factors on the ISGs. We demonstrated that this memory was attributed to accelerated recruitment of RNA polymerase II and transcription/chromatin factors, which coincided with acquisition of the histone H3.3 and H3K36me3 chromatin marks on memory ISGs. Similar memory was observed in bone marrow macrophages after IFNγ stimulation, suggesting that IFN stimulation modifies the shape of the innate immune response. Together, external signals can establish epigenetic memory in mammalian cells that imparts lasting adaptive performance upon various somatic cells.
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19
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Ne E, Palstra RJ, Mahmoudi T. Transcription: Insights From the HIV-1 Promoter. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 335:191-243. [DOI: 10.1016/bs.ircmb.2017.07.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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20
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Bratkowski M, Unarta IC, Zhu L, Shubbar M, Huang X, Liu X. Structural dissection of an interaction between transcription initiation and termination factors implicated in promoter-terminator cross-talk. J Biol Chem 2017; 293:1651-1665. [PMID: 29158257 DOI: 10.1074/jbc.m117.811521] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/10/2017] [Indexed: 11/06/2022] Open
Abstract
Functional cross-talk between the promoter and terminator of a gene has long been noted. Promoters and terminators are juxtaposed to form gene loops in several organisms, and gene looping is thought to be involved in transcriptional regulation. The general transcription factor IIB (TFIIB) and the C-terminal domain phosphatase Ssu72, essential factors of the transcription preinitiation complex and the mRNA processing and polyadenylation complex, respectively, are important for gene loop formation. TFIIB and Ssu72 interact both genetically and physically, but the molecular basis of this interaction is not known. Here we present a crystal structure of the core domain of TFIIB in two new conformations that differ in the relative distance and orientation of the two cyclin-like domains. The observed extraordinary conformational plasticity may underlie the binding of TFIIB to multiple transcription factors and promoter DNAs that occurs in distinct stages of transcription, including initiation, reinitiation, and gene looping. We mapped the binding interface of the TFIIB-Ssu72 complex using a series of systematic, structure-guided in vitro binding and site-specific photocross-linking assays. Our results indicate that Ssu72 competes with acidic activators for TFIIB binding and that Ssu72 disrupts an intramolecular TFIIB complex known to impede transcription initiation. We also show that the TFIIB-binding site on Ssu72 overlaps with the binding site of symplekin, a component of the mRNA processing and polyadenylation complex. We propose a hand-off model in which Ssu72 mediates a conformational transition in TFIIB, accounting for the role of Ssu72 in transcription reinitiation, gene looping, and promoter-terminator cross-talk.
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Affiliation(s)
- Matthew Bratkowski
- From the Cecil H. and Ida Green Center for Reproductive Biology Sciences and Division of Basic Research, Department of Obstetrics and Gynecology, and.,the Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390 and
| | - Ilona Christy Unarta
- the Department of Chemistry and.,Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Lizhe Zhu
- the Department of Chemistry and.,Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Murtada Shubbar
- From the Cecil H. and Ida Green Center for Reproductive Biology Sciences and Division of Basic Research, Department of Obstetrics and Gynecology, and.,the Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390 and
| | - Xuhui Huang
- the Department of Chemistry and.,Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xin Liu
- From the Cecil H. and Ida Green Center for Reproductive Biology Sciences and Division of Basic Research, Department of Obstetrics and Gynecology, and .,the Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390 and
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21
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The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae. Genetics 2017; 203:1563-99. [PMID: 27516616 DOI: 10.1534/genetics.112.145243] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022] Open
Abstract
Transcriptional silencing in Saccharomyces cerevisiae occurs at several genomic sites including the silent mating-type loci, telomeres, and the ribosomal DNA (rDNA) tandem array. Epigenetic silencing at each of these domains is characterized by the absence of nearly all histone modifications, including most prominently the lack of histone H4 lysine 16 acetylation. In all cases, silencing requires Sir2, a highly-conserved NAD(+)-dependent histone deacetylase. At locations other than the rDNA, silencing also requires additional Sir proteins, Sir1, Sir3, and Sir4 that together form a repressive heterochromatin-like structure termed silent chromatin. The mechanisms of silent chromatin establishment, maintenance, and inheritance have been investigated extensively over the last 25 years, and these studies have revealed numerous paradigms for transcriptional repression, chromatin organization, and epigenetic gene regulation. Studies of Sir2-dependent silencing at the rDNA have also contributed to understanding the mechanisms for maintaining the stability of repetitive DNA and regulating replicative cell aging. The goal of this comprehensive review is to distill a wide array of biochemical, molecular genetic, cell biological, and genomics studies down to the "nuts and bolts" of silent chromatin and the processes that yield transcriptional silencing.
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22
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Pascual-Garcia P, Debo B, Aleman JR, Talamas JA, Lan Y, Nguyen NH, Won KJ, Capelson M. Metazoan Nuclear Pores Provide a Scaffold for Poised Genes and Mediate Induced Enhancer-Promoter Contacts. Mol Cell 2017; 66:63-76.e6. [PMID: 28366641 DOI: 10.1016/j.molcel.2017.02.020] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 01/19/2017] [Accepted: 02/17/2017] [Indexed: 01/09/2023]
Abstract
Nuclear pore complex components (Nups) have been implicated in transcriptional regulation, yet what regulatory steps are controlled by metazoan Nups remains unclear. We identified the presence of multiple Nups at promoters, enhancers, and insulators in the Drosophila genome. In line with this binding, we uncovered a functional role for Nup98 in mediating enhancer-promoter looping at ecdysone-inducible genes. These genes were found to be stably associated with nuclear pores before and after activation. Although changing levels of Nup98 disrupted enhancer-promoter contacts, it did not affect ongoing transcription but instead compromised subsequent transcriptional activation or transcriptional memory. In support of the enhancer-looping role, we found Nup98 to gain and retain physical interactions with architectural proteins upon stimulation with ecdysone. Together, our data identify Nups as a class of architectural proteins for enhancers and supports a model in which animal genomes use the nuclear pore as an organizing scaffold for inducible poised genes.
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Affiliation(s)
- Pau Pascual-Garcia
- Department of Cell and Developmental Biology, Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Brian Debo
- Department of Cell and Developmental Biology, Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jennifer R Aleman
- Department of Cell and Developmental Biology, Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jessica A Talamas
- Department of Cell and Developmental Biology, Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yemin Lan
- Department of Cell and Developmental Biology, Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nha H Nguyen
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kyoung J Won
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Maya Capelson
- Department of Cell and Developmental Biology, Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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23
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Abstract
RNA polymerase 2 (pol2) associates with enhancers and promoters, followed by transcription initiation and subsequent pausing. Upon release, pol2 proceeds into productive elongation. A wide spread view of transcription holds that during elongation, pol2 and associated factors clear the promoter proximal region to track along the chromatin fiber until a termination site is encountered. However, several studies are compatible with alternative models. One common feature among these models is that transcription elongation results from movement of the gene along a complex consisting of pol2 and associated factors. Such a scenario predicts that active enhancers and promoters that are bound by transcription complexes, including pol2 are in dynamic physical proximity with the gene body in a manner paralleling pol2 processivity. This has indeed been observed by chromosome conformation capture under conditions of synchronous transcription. Here we discuss these observations and their implication for architectural models of transcription elongation.
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Affiliation(s)
- Kiwon Lee
- a Division of Hematology , The Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Gerd A Blobel
- a Division of Hematology , The Children's Hospital of Philadelphia , Philadelphia , PA , USA.,b Perelman School of Medicine , University of Pennsylvania , Philadelphia , PA , USA
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24
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Al-Hadid Q, Yang Y. R-loop: an emerging regulator of chromatin dynamics. Acta Biochim Biophys Sin (Shanghai) 2016; 48:623-31. [PMID: 27252122 DOI: 10.1093/abbs/gmw052] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 04/29/2016] [Indexed: 12/27/2022] Open
Abstract
The dynamic structure of chromatin, which exists in two conformational states: heterochromatin and euchromatin, alters the accessibility of the DNA to regulatory factors during transcription, replication, recombination, and DNA damage repair. Chemical modifications of histones and DNA, as well as adenosine triphospahate-dependent nucleosome remodeling, have been the major focus of research on chromatin dynamics over the past two decades. However, recent studies using a DNA-RNA hybrid-specific antibody and next-generation sequencing approaches have revealed that the formation of R-loops, one of the most common non-canonical DNA structures, is an emerging regulator of chromatin states. This review focuses on recent insights into the interplay between R-loop formation and the epigenetic modifications of chromatin in normal and disease states.
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Affiliation(s)
- Qais Al-Hadid
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Cancer Center, Duarte, CA 91010, USA
| | - Yanzhong Yang
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Cancer Center, Duarte, CA 91010, USA
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25
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Lamas-Maceiras M, Singh BN, Hampsey M, Freire-Picos MA. Promoter-Terminator Gene Loops Affect Alternative 3'-End Processing in Yeast. J Biol Chem 2016; 291:8960-8. [PMID: 26929407 DOI: 10.1074/jbc.m115.687491] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Indexed: 11/06/2022] Open
Abstract
Many eukaryotic genes undergo alternative 3'-end poly(A)-site selection producing transcript isoforms with 3'-UTRs of different lengths and post-transcriptional fates. Gene loops are dynamic structures that juxtapose the 3'-ends of genes with their promoters. Several functions have been attributed to looping, including memory of recent transcriptional activity and polarity of transcription initiation. In this study, we investigated the relationship between gene loops and alternative poly(A)-site. Using the KlCYC1 gene of the yeast Kluyveromyces lactis, which includes a single promoter and two poly(A) sites separated by 394 nucleotides, we demonstrate in two yeast species the formation of alternative gene loops (L1 and L2) that juxtapose the KlCYC1 promoter with either proximal or distal 3'-end processing sites, resulting in the synthesis of short and long forms of KlCYC1 mRNA. Furthermore, synthesis of short and long mRNAs and formation of the L1 and L2 loops are growth phase-dependent. Chromatin immunoprecipitation experiments revealed that the Ssu72 RNA polymerase II carboxyl-terminal domain phosphatase, a critical determinant of looping, peaks in early log phase at the proximal poly(A) site, but as growth phase advances, it extends to the distal site. These results define a cause-and-effect relationship between gene loops and alternative poly(A) site selection that responds to different physiological signals manifested by RNA polymerase II carboxyl-terminal domain phosphorylation status.
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Affiliation(s)
- Mónica Lamas-Maceiras
- From the Departamento de Biología Celular e Molecular, Facultad de Ciencias, Universidade da Coruña, Campus de A Coruña, Rúa da Fraga 10, 15008 A Coruña, Spain and
| | - Badri Nath Singh
- the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - Michael Hampsey
- the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - María A Freire-Picos
- From the Departamento de Biología Celular e Molecular, Facultad de Ciencias, Universidade da Coruña, Campus de A Coruña, Rúa da Fraga 10, 15008 A Coruña, Spain and
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26
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Cloutier SC, Wang S, Ma WK, Al Husini N, Dhoondia Z, Ansari A, Pascuzzi PE, Tran EJ. Regulated Formation of lncRNA-DNA Hybrids Enables Faster Transcriptional Induction and Environmental Adaptation. Mol Cell 2016; 61:393-404. [PMID: 26833086 DOI: 10.1016/j.molcel.2015.12.024] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/23/2015] [Accepted: 12/18/2015] [Indexed: 10/22/2022]
Abstract
Long non-coding (lnc)RNAs, once thought to merely represent noise from imprecise transcription initiation, have now emerged as major regulatory entities in all eukaryotes. In contrast to the rapidly expanding identification of individual lncRNAs, mechanistic characterization has lagged behind. Here we provide evidence that the GAL lncRNAs in the budding yeast S. cerevisiae promote transcriptional induction in trans by formation of lncRNA-DNA hybrids or R-loops. The evolutionarily conserved RNA helicase Dbp2 regulates formation of these R-loops as genomic deletion or nuclear depletion results in accumulation of these structures across the GAL cluster gene promoters and coding regions. Enhanced transcriptional induction is manifested by lncRNA-dependent displacement of the Cyc8 co-repressor and subsequent gene looping, suggesting that these lncRNAs promote induction by altering chromatin architecture. Moreover, the GAL lncRNAs confer a competitive fitness advantage to yeast cells because expression of these non-coding molecules correlates with faster adaptation in response to an environmental switch.
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Affiliation(s)
- Sara C Cloutier
- Department of Biochemistry, Purdue University, BCHM 305, 175 S. University Street, West Lafayette, IN 47907, USA
| | - Siwen Wang
- Department of Biochemistry, Purdue University, BCHM 305, 175 S. University Street, West Lafayette, IN 47907, USA
| | - Wai Kit Ma
- Department of Biochemistry, Purdue University, BCHM 305, 175 S. University Street, West Lafayette, IN 47907, USA
| | - Nadra Al Husini
- Department of Biological Sciences, 5047 Gullen Mall, Wayne State University, Detroit, MI 48202, USA
| | - Zuzer Dhoondia
- Department of Biological Sciences, 5047 Gullen Mall, Wayne State University, Detroit, MI 48202, USA
| | - Athar Ansari
- Department of Biological Sciences, 5047 Gullen Mall, Wayne State University, Detroit, MI 48202, USA
| | - Pete E Pascuzzi
- Department of Biochemistry, Purdue University, BCHM 305, 175 S. University Street, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, Hansen Life Sciences Research Building, Room 141, 201 S. University Street, West Lafayette, IN 47907, USA; Purdue University Libraries, 504 W. State Street, West Lafayette, IN 47907, USA.
| | - Elizabeth J Tran
- Department of Biochemistry, Purdue University, BCHM 305, 175 S. University Street, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, Hansen Life Sciences Research Building, Room 141, 201 S. University Street, West Lafayette, IN 47907, USA.
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27
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Mayfield JE, Burkholder NT, Zhang YJ. Dephosphorylating eukaryotic RNA polymerase II. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:372-87. [PMID: 26779935 DOI: 10.1016/j.bbapap.2016.01.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/11/2016] [Accepted: 01/14/2016] [Indexed: 12/20/2022]
Abstract
The phosphorylation state of the C-terminal domain of RNA polymerase II is required for the temporal and spatial recruitment of various factors that mediate transcription and RNA processing throughout the transcriptional cycle. Therefore, changes in CTD phosphorylation by site-specific kinases/phosphatases are critical for the accurate transmission of information during transcription. Unlike kinases, CTD phosphatases have been traditionally neglected as they are thought to act as passive negative regulators that remove all phosphate marks at the conclusion of transcription. This over-simplified view has been disputed in recent years and new data assert the active and regulatory role phosphatases play in transcription. We now know that CTD phosphatases ensure the proper transition between different stages of transcription, balance the distribution of phosphorylation for accurate termination and re-initiation, and prevent inappropriate expression of certain genes. In this review, we focus on the specific roles of CTD phosphatases in regulating transcription. In particular, we emphasize how specificity and timing of dephosphorylation are achieved for these phosphatases and consider the various regulatory factors that affect these dynamics.
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Affiliation(s)
- Joshua E Mayfield
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Nathaniel T Burkholder
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
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28
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Vad-Nielsen J, Nielsen AL. Beyond the histone tale: HP1α deregulation in breast cancer epigenetics. Cancer Biol Ther 2015; 16:189-200. [PMID: 25588111 DOI: 10.1080/15384047.2014.1001277] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Heterochromatin protein 1α (HP1α) encoded from the CBX5-gene is an evolutionary conserved protein that binds histone H3 di- or tri-methylated at position lysine 9 (H3K9me2/3), a hallmark for heterochromatin, and has an essential role in forming higher order chromatin structures. HP1α has diverse functions in heterochromatin formation, gene regulation, and mitotic progression, and forms complex networks of gene, RNA, and protein interactions. Emerging evidence has shown that HP1α serves a unique biological role in breast cancer related processes and in particular for epigenetic control mechanisms involved in aberrant cell proliferation and metastasis. However, how HP1α deregulation plays dual mechanistic functions for cancer cell proliferation and metastasis suppression and the underlying cellular mechanisms are not yet comprehensively described. In this paper we provide an overview of the role of HP1α as a new sight of epigenetics in proliferation and metastasis of human breast cancer. This highlights the importance of addressing HP1α in breast cancer diagnostics and therapeutics.
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Key Words
- CBX, chromobox homolog
- CD, chromo domain
- CSC, cancer stem cells
- CSD, cromo shadow domain
- CTE, C-terminal extension
- DNMT, DNA-methyltransferase
- EMT, epithelial-to-mesenchymal transition
- HDMT, histone demethylase
- HMT, histone methyltransferase
- HP1, heterochromatin protein 1
- NTE, N-terminal extension
- PEV, position effect variegation
- SOMU, sumoylation
- TGS, transcriptional gene silencing
- TSS, transcriptional start site
- bp, base pair
- breast-cancer, metastasis
- chromatin
- epigenetics
- histone-modifications
- invasion
- mitosis
- proliferation
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29
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Dieci G, Fermi B, Bosio MC. Investigating transcription reinitiation through in vitro approaches. Transcription 2015; 5:e27704. [PMID: 25764113 DOI: 10.4161/trns.27704] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
By influencing the number of RNA molecules repeatedly synthesized from the same gene, the control of transcription reinitiation has the potential to shape the transcriptome. Transcription reinitiation mechanisms have been mainly addressed in vitro, through approaches based on both crude and reconstituted systems. These studies support the notion that transcription reinitiation and its regulation rely on dedicated networks of molecular interactions within transcription machineries. At the same time, comparison with in vivo transcription rates suggests that additional mechanisms, factors and conditions must exist in the nucleus, whose biochemical elucidation is a fascinating challenge for future in vitro transcription studies.
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Affiliation(s)
- Giorgio Dieci
- a Dipartimento di Bioscienze; Università degli Studi di Parma; Parma, Italy
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30
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Medler S, Ansari A. Gene looping facilitates TFIIH kinase-mediated termination of transcription. Sci Rep 2015; 5:12586. [PMID: 26286112 PMCID: PMC4541409 DOI: 10.1038/srep12586] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 06/08/2015] [Indexed: 12/14/2022] Open
Abstract
TFIIH is a general transcription factor with kinase and helicase activities. The kinase activity resides in the Kin28 subunit of TFIIH. The role of Kin28 kinase in the early steps of transcription is well established. Here we report a novel role of Kin28 in the termination of transcription. We show that RNAPII reads through a termination signal upon kinase inhibition. Furthermore, the recruitment of termination factors towards the 3′ end of a gene was compromised in the kinase mutant, thus confirming the termination defect. A concomitant decrease in crosslinking of termination factors near the 5′ end of genes was also observed in the kinase-defective mutant. Simultaneous presence of termination factors towards both the ends of a gene is indicative of gene looping; while the loss of termination factor occupancy from the distal ends suggest the abolition of a looped gene conformation. Accordingly, CCC analysis revealed that the looped architecture of genes was severely compromised in the Kin28 kinase mutant. In a looping defective sua7-1 mutant, even the enzymatically active Kin28 kinase could not rescue the termination defect. These results strongly suggest a crucial role of Kin28 kinase-dependent gene looping in the termination of transcription in budding yeast.
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Affiliation(s)
- Scott Medler
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall Detroit, MI 48202
| | - Athar Ansari
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall Detroit, MI 48202
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31
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Morris DP, Lei B, Longo LD, Bomsztyk K, Schwinn DA, Michelotti GA. Temporal Dissection of Rate Limiting Transcriptional Events Using Pol II ChIP and RNA Analysis of Adrenergic Stress Gene Activation. PLoS One 2015; 10:e0134442. [PMID: 26244980 PMCID: PMC4526373 DOI: 10.1371/journal.pone.0134442] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 07/10/2015] [Indexed: 12/13/2022] Open
Abstract
In mammals, increasing evidence supports mechanisms of co-transcriptional gene regulation and the generality of genetic control subsequent to RNA polymerase II (Pol II) recruitment. In this report, we use Pol II Chromatin Immunoprecipitation to investigate relationships between the mechanistic events controlling immediate early gene (IEG) activation following stimulation of the α1a-Adrenergic Receptor expressed in rat-1 fibroblasts. We validate our Pol II ChIP assay by comparison to major transcriptional events assessable by microarray and PCR analysis of precursor and mature mRNA. Temporal analysis of Pol II density suggests that reduced proximal pausing often enhances gene expression and was essential for Nr4a3 expression. Nevertheless, for Nr4a3 and several other genes, proximal pausing delayed the time required for initiation of productive elongation, consistent with a role in ensuring transcriptional fidelity. Arrival of Pol II at the 3’ cleavage site usually correlated with increased polyadenylated mRNA; however, for Nfil3 and probably Gprc5a expression was delayed and accompanied by apparent pre-mRNA degradation. Intragenic pausing not associated with polyadenylation was also found to regulate and delay Gprc5a expression. Temporal analysis of Nr4a3, Dusp5 and Nfil3 shows that transcription of native IEG genes can proceed at velocities of 3.5 to 4 kilobases/min immediately after activation. Of note, all of the genes studied here also used increased Pol II recruitment as an important regulator of expression. Nevertheless, the generality of co-transcriptional regulation during IEG activation suggests temporal and integrated analysis will often be necessary to distinguish causative from potential rate limiting mechanisms.
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Affiliation(s)
- Daniel P. Morris
- Center for Perinatal Biology, Loma Linda University, Loma Linda, California, United States of America
- * E-mail:
| | - Beilei Lei
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Lawrence D. Longo
- Center for Perinatal Biology, Loma Linda University, Loma Linda, California, United States of America
| | - Karol Bomsztyk
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Debra A. Schwinn
- Department of Anesthesiology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
- Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - Gregory A. Michelotti
- Department of Medicine, Division of Gastroenterology, Duke University Medical Center, Durham, North Carolina, United States of America
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32
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Morelle C, Sterkers Y, Crobu L, MBang-Benet DE, Kuk N, Portalès P, Bastien P, Pagès M, Lachaud L. The nucleoporin Mlp2 is involved in chromosomal distribution during mitosis in trypanosomatids. Nucleic Acids Res 2015; 43:4013-27. [PMID: 25690889 PMCID: PMC4417144 DOI: 10.1093/nar/gkv056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 01/15/2015] [Indexed: 12/31/2022] Open
Abstract
Nucleoporins are evolutionary conserved proteins mainly involved in the constitution of the nuclear pores and trafficking between the nucleus and cytoplasm, but are also increasingly viewed as main actors in chromatin dynamics and intra-nuclear mitotic events. Here, we determined the cellular localization of the nucleoporin Mlp2 in the 'divergent' eukaryotes Leishmania major and Trypanosoma brucei. In both protozoa, Mlp2 displayed an atypical localization for a nucleoporin, essentially intranuclear, and preferentially in the periphery of the nucleolus during interphase; moreover, it relocated at the mitotic spindle poles during mitosis. In T. brucei, where most centromeres have been identified, TbMlp2 was found adjacent to the centromeric sequences, as well as to a recently described unconventional kinetochore protein, in the periphery of the nucleolus, during interphase and from the end of anaphase onwards. TbMlp2 and the centromeres/kinetochores exhibited a differential migration towards the poles during mitosis. RNAi knockdown of TbMlp2 disrupted the mitotic distribution of chromosomes, leading to a surprisingly well-tolerated aneuploidy. In addition, diploidy was restored in a complementation assay where LmMlp2, the orthologue of TbMlp2 in Leishmania, was expressed in TbMlp2-RNAi-knockdown parasites. Taken together, our results demonstrate that Mlp2 is involved in the distribution of chromosomes during mitosis in trypanosomatids.
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Affiliation(s)
- Christelle Morelle
- Laboratory of Parasitology-Mycology, Faculty of Medicine, University Montpellier 1, Montpellier F34090, France CNRS 5290-IRD 224-University Montpellier 1&2 (UMR 'MiVEGEC'), Montpellier F34090, France Department of Parasitology-Mycology, University Hospital Centre (CHU), Montpellier F34090, France
| | - Yvon Sterkers
- Laboratory of Parasitology-Mycology, Faculty of Medicine, University Montpellier 1, Montpellier F34090, France CNRS 5290-IRD 224-University Montpellier 1&2 (UMR 'MiVEGEC'), Montpellier F34090, France Department of Parasitology-Mycology, University Hospital Centre (CHU), Montpellier F34090, France
| | - Lucien Crobu
- CNRS 5290-IRD 224-University Montpellier 1&2 (UMR 'MiVEGEC'), Montpellier F34090, France
| | - Diane-Ethna MBang-Benet
- Laboratory of Parasitology-Mycology, Faculty of Medicine, University Montpellier 1, Montpellier F34090, France
| | - Nada Kuk
- Laboratory of Parasitology-Mycology, Faculty of Medicine, University Montpellier 1, Montpellier F34090, France
| | - Pierre Portalès
- Department of Immunology, University Hospital Centre (CHU), Montpellier F34090, France
| | - Patrick Bastien
- Laboratory of Parasitology-Mycology, Faculty of Medicine, University Montpellier 1, Montpellier F34090, France CNRS 5290-IRD 224-University Montpellier 1&2 (UMR 'MiVEGEC'), Montpellier F34090, France Department of Parasitology-Mycology, University Hospital Centre (CHU), Montpellier F34090, France
| | - Michel Pagès
- CNRS 5290-IRD 224-University Montpellier 1&2 (UMR 'MiVEGEC'), Montpellier F34090, France
| | - Laurence Lachaud
- Laboratory of Parasitology-Mycology, Faculty of Medicine, University Montpellier 1, Montpellier F34090, France CNRS 5290-IRD 224-University Montpellier 1&2 (UMR 'MiVEGEC'), Montpellier F34090, France
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33
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Chen Y, Zhang L, Estarás C, Choi SH, Moreno L, Karn J, Moresco JJ, Yates JR, Jones KA. A gene-specific role for the Ssu72 RNAPII CTD phosphatase in HIV-1 Tat transactivation. Genes Dev 2014; 28:2261-75. [PMID: 25319827 PMCID: PMC4201287 DOI: 10.1101/gad.250449.114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
HIV-1 Tat stimulates transcription elongation by recruiting the P-TEFb (positive transcription elongation factor-b) (CycT1:CDK9) C-terminal domain (CTD) kinase to the HIV-1 promoter. Here we show that Tat transactivation also requires the Ssu72 CTD Ser5P (S5P)-specific phosphatase, which mediates transcription termination and intragenic looping at eukaryotic genes. Importantly, HIV-1 Tat interacts directly with Ssu72 and strongly stimulates its CTD phosphatase activity. We found that Ssu72 is essential for Tat:P-TEFb-mediated phosphorylation of the S5P-CTD in vitro. Interestingly, Ssu72 also stimulates nascent HIV-1 transcription in a phosphatase-dependent manner in vivo. Chromatin immunoprecipitation (ChIP) experiments reveal that Ssu72, like P-TEFb and AFF4, is recruited by Tat to the integrated HIV-1 proviral promoter in TNF-α signaling 2D10 T cells and leaves the elongation complex prior to the termination site. ChIP-seq (ChIP combined with deep sequencing) and GRO-seq (genome-wide nuclear run-on [GRO] combined with deep sequencing) analysis further reveals that Ssu72 predominantly colocalizes with S5P-RNAPII (RNA polymerase II) at promoters in human embryonic stem cells, with a minor peak in the terminator region. A few genes, like NANOG, also have high Ssu72 at the terminator. Ssu72 is not required for transcription at most cellular genes but has a modest effect on cotranscriptional termination. We conclude that Tat alters the cellular function of Ssu72 to stimulate viral gene expression and facilitate the early S5P-S2P transition at the integrated HIV-1 promoter.
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Affiliation(s)
- Yupeng Chen
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Lirong Zhang
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Conchi Estarás
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Seung H Choi
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Luis Moreno
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - James J Moresco
- Department of Chemical Physiology and Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - John R Yates
- Department of Chemical Physiology and Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Katherine A Jones
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
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34
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Olayanju B, Hampsey JJ, Hampsey M. Genetic analysis of the Warburg effect in yeast. Adv Biol Regul 2014; 57:185-92. [PMID: 25446884 DOI: 10.1016/j.jbior.2014.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 09/03/2014] [Indexed: 01/20/2023]
Abstract
We recently discovered that the Warburg effect, defined by the dramatically enhanced metabolism of glucose to pyruvate, even in well-oxygenated cancer cells, can occur as a consequence of mutations that enhance lipid biosynthesis at the expense of respiratory capacity. Specifically, mutations in the E1 subunit of either of two respiratory enzymes, pyruvate dehydrogenase (PDC) or α-ketoglutarate dehydrogenase (KGDC), change substrate specificity from the 3-carbon α-ketoacid pyruvate, or the 5-carbon α-ketoacid α-ketoglutarate, to the 4-carbon α-ketoacid oxaloacetate (OADC). These mutations result in OADC-catalyzed synthesis of malonyl-CoA (MaCoA), the essential precursor of all fatty acids. These mutants arose as spontaneous suppressors of a yeast acc1(cs) cold-sensitive mutation encoding an altered form of AcCoA carboxylase (Acc1) that fails to produce MaCoA at the restrictive temperature (16 °C). Notably, these suppressors are respiratory defective as a result of the same nuclear mutations that suppress acc1(cs). These mutants also suppress sensitivity to Soraphen A, a potent inhibitor of Acc1 activity, at normal temperature (30 °C). To our knowledge, OADC activity has never been identified in eukaryotic cells. Our results offer a novel perspective on the Warburg effect: the reprogramming of energy metabolism in cancer cells as a consequence of mutational impairment of respiration to meet the fatty acid requirements of rapidly proliferating cells. We suggest OADC activity is a common feature of cancer cells and represents a novel target for the development of chemotherapeutics.
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Affiliation(s)
- Bola Olayanju
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - James Jensen Hampsey
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Michael Hampsey
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA.
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35
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Zuchegna C, Aceto F, Bertoni A, Romano A, Perillo B, Laccetti P, Gottesman ME, Avvedimento EV, Porcellini A. Mechanism of retinoic acid-induced transcription: histone code, DNA oxidation and formation of chromatin loops. Nucleic Acids Res 2014; 42:11040-55. [PMID: 25217584 PMCID: PMC4176188 DOI: 10.1093/nar/gku823] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Histone methylation changes and formation of chromatin loops involving enhancers, promoters and 3′ end regions of genes have been variously associated with active transcription in eukaryotes. We have studied the effect of activation of the retinoic A receptor, at the RARE–promoter chromatin of CASP9 and CYP26A1 genes, 15 and 45 min following RA exposure, and we found that histone H3 lysines 4 and 9 are demethylated by the lysine-specific demethylase, LSD1 and by the JMJ-domain containing demethylase, D2A. The action of the oxidase (LSD1) and a dioxygenase (JMJD2A) in the presence of Fe++ elicits an oxidation wave that locally modifies the DNA and recruits the enzymes involved in base and nucleotide excision repair (BER and NER). These events are essential for the formation of chromatin loop(s) that juxtapose the RARE element with the 5′ transcription start site and the 3′ end of the genes. The RARE bound-receptor governs the 5′ and 3′ end selection and directs the productive transcription cycle of RNA polymerase. These data mechanistically link chromatin loops, histone methylation changes and localized DNA repair with transcription.
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Affiliation(s)
- Candida Zuchegna
- Dipartimento di Biologia, Università Federico II, 80126 Napoli, Italy
| | - Fabiana Aceto
- Dipartimento di Medicina e di Scienze della Salute, Università del Molise, 86100 Campobasso, Italy
| | - Alessandra Bertoni
- Dipartimento di Medicina Molecolare e Biotecnologie mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy
| | - Antonella Romano
- Dipartimento di Biologia, Università Federico II, 80126 Napoli, Italy
| | - Bruno Perillo
- Istituto di Scienze dell'Alimentazione, C.N.R., 83100 Avellino, Italy
| | - Paolo Laccetti
- Dipartimento di Biologia, Università Federico II, 80126 Napoli, Italy
| | - Max E Gottesman
- Institute of Cancer Research, Columbia University Medical Center, New York, NY 10032, USA
| | - Enrico V Avvedimento
- Dipartimento di Medicina Molecolare e Biotecnologie mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy
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36
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Chen M, Gartenberg MR. Coordination of tRNA transcription with export at nuclear pore complexes in budding yeast. Genes Dev 2014; 28:959-70. [PMID: 24788517 PMCID: PMC4018494 DOI: 10.1101/gad.236729.113] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
tRNAs are encoded by RNA polymerase III-transcribed genes that reside at seemingly random intervals along budding yeast chromosomes. Here, Chen and Gartenberg examined the spatial and temporal aspects of tRNA gene expression. Unexpectedly, they found that tRNA genes are transcribed in a periodic manner during cell cycle progression. Moreover, tRNA genes migrate to nuclear pore complexes when transcription peaks in M phase. This study demonstrates how RNA polymerase III-transcribed genes are gated to nuclear pore complexes in yeast. tRNAs are encoded by RNA polymerase III-transcribed genes that reside at seemingly random intervals along the chromosomes of budding yeast. Existing evidence suggests that the genes congregate together at the nucleolus and/or centromeres. In this study, we re-examined spatial and temporal aspects of tRNA gene (tDNA) expression. We show that tDNA transcription fluctuates during cell cycle progression. In M phase, when tRNA synthesis peaks, tDNAs localize at nuclear pore complexes (NPCs). Docking of a tDNA requires the DNA sequence of the contacted gene, nucleoporins Nup60 and Nup2, and cohesin. Characterization of mutants that block NPC localization revealed that docking is a consequence of elevated tDNA transcription. NPC–tDNA contact falters in the absence of the principal exportin of nascent tRNA, Los1, and genetic assays indicate that gating of tDNAs at NPCs favors cytoplasmic accumulation of functional tRNA. Collectively, the data suggest that tDNAs associate with NPCs to coordinate RNA polymerase III transcription with the nuclear export of pre-tRNA. The M-phase specificity of NPC contact reflects a regulatory mechanism that may have evolved, in part, to avoid collisions between DNA replication forks and transcribing RNA polymerase III machinery at NPCs.
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Affiliation(s)
- Miao Chen
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854, USA
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37
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Dissecting the cis and trans elements that regulate adjacent-gene coregulation in Saccharomyces cerevisiae. EUKARYOTIC CELL 2014; 13:738-48. [PMID: 24706020 DOI: 10.1128/ec.00317-13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The relative positions that genes occupy on their respective chromosomes can play a critical role in determining how they are regulated at the transcriptional level. For example, a significant fraction of the genes from a variety of coregulated gene sets, including the ribosomal protein (RP) and the rRNA and ribosome biogenesis (RRB) regulons, exist as immediate, adjacent gene pairs. These gene pairs occur in all possible divergent, tandem, and convergent orientations. Adjacent-gene pairing in these regulons is associated with a tighter transcriptional coregulation than is observed for nonpaired genes of the same regulons. In order to define the cis and trans factors that regulate adjacent-gene coregulation (AGC), we conducted a mutational analysis of the convergently oriented RRB gene pair MPP10-YJR003C. We observed that coupled corepression of the gene pair under heat shock was abrogated when the two genes were separated by an actively expressed RNA polymerase (Pol) II transcription unit (the LEU2 gene) but not when the inserted LEU2 gene was repressed. In contrast, the insertion of an RNA Pol III-transcribed tRNA (Thr) gene did not disrupt the coregulated repression of MPP10 and YJR003C. A targeted screen of mutants defective in regulating chromosome architecture revealed that the Spt20, Snf2, and Chd1 proteins were required for coupling the repression of YJR003C to that of MPP10. Nucleosome occupancy assays performed across the MPP10 and YJR003C promoter regions revealed that the mechanism of corepression of the gene pair was not related to the repositioning of nucleosomes across the respective gene promoters.
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38
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Jurado AR, Tan D, Jiao X, Kiledjian M, Tong L. Structure and function of pre-mRNA 5'-end capping quality control and 3'-end processing. Biochemistry 2014; 53:1882-98. [PMID: 24617759 PMCID: PMC3977584 DOI: 10.1021/bi401715v] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Messenger RNA precursors (pre-mRNAs)
are produced as the nascent
transcripts of RNA polymerase II (Pol II) in eukaryotes and must undergo
extensive maturational processing, including 5′-end capping,
splicing, and 3′-end cleavage and polyadenylation. This review
will summarize the structural and functional information reported
over the past few years on the large machinery required for the 3′-end
processing of most pre-mRNAs, as well as the distinct machinery for
the 3′-end processing of replication-dependent histone pre-mRNAs,
which have provided great insights into the proteins and their subcomplexes
in these machineries. Structural and biochemical studies have also
led to the identification of a new class of enzymes (the DXO family
enzymes) with activity toward intermediates of the 5′-end capping
pathway. Functional studies demonstrate that these enzymes are part
of a novel quality surveillance mechanism for pre-mRNA 5′-end
capping. Incompletely capped pre-mRNAs are produced in yeast and human
cells, in contrast to the general belief in the field that capping
always proceeds to completion, and incomplete capping leads to defects
in splicing and 3′-end cleavage in human cells. The DXO family
enzymes are required for the detection and degradation of these defective
RNAs.
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Affiliation(s)
- Ashley R Jurado
- Department of Biological Sciences, Columbia University , New York, New York 10027, United States
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Gaillard H, Aguilera A. Cleavage factor I links transcription termination to DNA damage response and genome integrity maintenance in Saccharomyces cerevisiae. PLoS Genet 2014; 10:e1004203. [PMID: 24603480 PMCID: PMC3945788 DOI: 10.1371/journal.pgen.1004203] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 01/10/2014] [Indexed: 12/18/2022] Open
Abstract
During transcription, the nascent pre-mRNA undergoes a series of processing steps before being exported to the cytoplasm. The 3'-end processing machinery involves different proteins, this function being crucial to cell growth and viability in eukaryotes. Here, we found that the rna14-1, rna15-1, and hrp1-5 alleles of the cleavage factor I (CFI) cause sensitivity to UV-light in the absence of global genome repair in Saccharomyces cerevisiae. Unexpectedly, CFI mutants were proficient in UV-lesion repair in a transcribed gene. DNA damage checkpoint activation and RNA polymerase II (RNAPII) degradation in response to UV were delayed in CFI-deficient cells, indicating that CFI participates in the DNA damage response (DDR). This is further sustained by the synthetic growth defects observed between rna14-1 and mutants of different repair pathways. Additionally, we found that rna14-1 suffers severe replication progression defects and that a functional G1/S checkpoint becomes essential in avoiding genetic instability in those cells. Thus, CFI function is required to maintain genome integrity and to prevent replication hindrance. These findings reveal a new function for CFI in the DDR and underscore the importance of coordinating transcription termination with replication in the maintenance of genomic stability.
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Affiliation(s)
- Hélène Gaillard
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, Sevilla, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, Sevilla, Spain
- * E-mail:
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40
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Lv YJ, Wang X, Ma Q, Bai X, Li BZ, Zhang W, Yuan YJ. Proteomic analysis reveals complex metabolic regulation in Saccharomyces cerevisiae cells against multiple inhibitors stress. Appl Microbiol Biotechnol 2014; 98:2207-21. [PMID: 24442506 DOI: 10.1007/s00253-014-5519-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 12/20/2013] [Accepted: 12/28/2013] [Indexed: 11/24/2022]
Abstract
Toxic compounds including acids, furans, and phenols (AFP) were generated from the pretreatment of lignocellulose. We cultivated Saccharomyces cerevisiae cells in a batch mode, besides the cell culture of original yeast strain in AFP-free medium which was referred as C0, three independent subcultures were cultivated under multiple inhibitors AFP and were referred as C1, C2, and C3 in time sequence. Comparing to C0, the cell density was lowered while the ethanol yield was maintained stably in the three yeast cultures under AFP stress, and the lag phase of C1 was extended while the lag phases of C2 and C3 were not extended. In proteomic analysis, 194 and 215 unique proteins were identified as differently expressed proteins at lag phase and exponential phase, respectively. Specifically, the yeast cells co-regulated protein folding and protein synthesis process to prevent the generation of misfolded proteins and to save cellular energy, they increased the activity of glycolysis, redirected metabolic flux towards phosphate pentose pathway and the biosynthesis of ethanol instead of the biosynthesis of glycerol and acetic acid, and they upregulated several oxidoreductases especially at lag phase and induced programmed cell death at exponential phase. When the yeast cells were cultivated under AFP stress, the new metabolism homeostasis in favor of cellular energy and redox homeostasis was generated in C1, then it was inherited and optimized in C2 and C3, enabling the yeast cells in C2 and C3 to enter the exponential phase in a short period after inoculation, which thus significantly shortened the fermentation time.
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Affiliation(s)
- Ya-Jin Lv
- Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin, 300072, People's Republic of China
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41
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Abstract
Gene looping, defined as the physical interaction between the promoter and terminator regions of a RNA polymerase II-transcribed gene, is widespread in yeast and mammalian cells. Gene looping has been shown to play important roles in transcription. Gene-loop formation is dependent on regulatory proteins localized at the 5' and 3' ends of genes, such as TFIIB. However, whether other factors contribute to gene looping remains to be elucidated. Here, we investigated the contribution of intrinsic DNA and chromatin structures to gene looping. We found that Saccharomyces cerevisiae looped genes show high DNA bendability around middle and 3/4 regions in open reading frames (ORFs). This bendability pattern is conserved between yeast species, whereas the position of bendability peak varies substantially among species. Looped genes in human cells also show high DNA bendability. Nucleosome positioning around looped ORF middle regions is unstable. We also present evidence indicating that this unstable nucleosome positioning is involved in gene looping. These results suggest a mechanism by which DNA bendability and unstable nucleosome positioning could assist in the formation of gene loops.
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Affiliation(s)
- Zhiming Dai
- Department of Electronics and Communication Engineering, School of Information Science and Technology, Sun Yat-Sen University, Guangzhou, China
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42
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Pearson EL, Moore CL. Dismantling promoter-driven RNA polymerase II transcription complexes in vitro by the termination factor Rat1. J Biol Chem 2013; 288:19750-9. [PMID: 23689372 DOI: 10.1074/jbc.m112.434985] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proper RNA polymerase II (Pol II) transcription termination is essential to generate stable transcripts, to prevent interference at downstream loci, and to recycle Pol II back to the promoter (1-3). As such, termination is an intricately controlled process that is tightly regulated by a variety of different cis- and trans-acting factors (4, 5). Although many eukaryotic termination factors have been identified to date, the details of the precise molecular mechanisms governing termination remain to be elucidated. We devised an in vitro transcription system to study specific Pol II termination. We show for the first time that the exonucleolytic Rat1·Rai1 complex can elicit the release of stalled Pol II in vitro and can do so in the absence of other factors. We also find that Rtt103, which interacts with the Pol II C-terminal domain (CTD) and with Rat1, can rescue termination activity of an exonucleolytically deficient Rat1 mutant. In light of our findings, we posit a model whereby functional nucleolytic activity is not the feature of Rat1 that ultimately promotes termination. Degradation of the nascent transcript allows Rat1 to pursue Pol II in a guided fashion and arrive at the site of RNA exit from Pol II. Upon this arrival, however, it is perhaps the specific and direct contact between Rat1 and Pol II that transmits the signal to terminate transcription.
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Affiliation(s)
- Erika L Pearson
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Hebenstreit D. Are gene loops the cause of transcriptional noise? Trends Genet 2013; 29:333-8. [PMID: 23663933 DOI: 10.1016/j.tig.2013.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/22/2013] [Accepted: 04/02/2013] [Indexed: 12/14/2022]
Abstract
Expression levels of the same mRNA or protein vary significantly among the cells of an otherwise identical population. Such biological noise has great functional implications and is largely due to transcriptional bursting, the episodic production of mRNAs in short, intense bursts, interspersed by periods of transcriptional inactivity. Bursting has been demonstrated in a wide range of pro- and eukaryotic species, attesting to its universal importance. However, the mechanistic origins of bursting remain elusive. A different type of phenomenon, which has also been suggested to be widespread, is the physical interaction between the promoter and 3' end of a gene. Several functional roles have been proposed for such gene loops, including the facilitation of transcriptional reinitiation. Here, I discuss the most recent findings related to these subjects and argue that gene loops are a likely cause of transcriptional bursting and, thus, biological noise.
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Affiliation(s)
- Daniel Hebenstreit
- School of Life Sciences, Gibbet Hill Campus, The University of Warwick, Coventry, CV4 7AL, UK.
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DNA looping facilitates targeting of a chromatin remodeling enzyme. Mol Cell 2013; 50:93-103. [PMID: 23478442 DOI: 10.1016/j.molcel.2013.02.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 01/15/2013] [Accepted: 01/30/2013] [Indexed: 12/14/2022]
Abstract
ATP-dependent chromatin remodeling enzymes are highly abundant and play pivotal roles regulating DNA-dependent processes. The mechanisms by which they are targeted to specific loci have not been well understood on a genome-wide scale. Here, we present evidence that a major targeting mechanism for the Isw2 chromatin remodeling enzyme to specific genomic loci is through sequence-specific transcription factor (TF)-dependent recruitment. Unexpectedly, Isw2 is recruited in a TF-dependent fashion to a large number of loci without TF binding sites. Using the 3C assay, we show that Isw2 can be targeted by Ume6- and TFIIB-dependent DNA looping. These results identify DNA looping as a mechanism for the recruitment of a chromatin remodeling enzyme and define a function for DNA looping. We also present evidence suggesting that Ume6-dependent DNA looping is involved in chromatin remodeling and transcriptional repression, revealing a mechanism by which the three-dimensional folding of chromatin affects DNA-dependent processes.
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Stress-Mediated Alterations in Chromatin Architecture Correlate with Down-Regulation of a Gene Encoding 60S rpL32 in Rice. ACTA ACUST UNITED AC 2013; 54:528-40. [DOI: 10.1093/pcp/pct012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Henriques T, Ji Z, Tan-Wong SM, Carmo AM, Tian B, Proudfoot NJ, Moreira A. Transcription termination between polo and snap, two closely spaced tandem genes of D. melanogaster. Transcription 2013; 3:198-212. [PMID: 22992452 PMCID: PMC3654770 DOI: 10.4161/trns.21967] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Transcription termination of RNA polymerase II between closely spaced genes is an important, though poorly understood, mechanism. This is true, in particular, in the Drosophila genome, where approximately 52% of tandem genes are separated by less than 1 kb. We show that a set of Drosophila tandem genes has a negative correlation of gene expression and display several molecular marks indicative of promoter pausing. We find that an intergenic spacing of 168 bp is sufficient for efficient transcription termination between the polo-snap tandem gene pair, by a mechanism that is independent of Pcf11 and Xrn2. In contrast, analysis of a tandem gene pair containing a longer intergenic region reveals that termination occurs farther downstream of the poly(A) signal and is, in this case, dependent on Pcf11 and Xrn2. For polo-snap, displacement of poised polymerase from the snap promoter by depletion of the initiation factor TFIIB results in an increase of polo transcriptional read-through. This suggests that poised polymerase is necessary for transcription termination. Interestingly, we observe that polo forms a TFIIB dependent gene loop between its promoter and terminator regions. Furthermore, in a plasmid containing the polo-snap locus, deletion of the polo promoter causes an increase in snap expression, as does deletion of polo poly(A) signals. Taken together, our results indicate that polo forms a gene loop and polo transcription termination occurs by an Xrn2 and Pcf11 independent mechanism that requires TFIIB.
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Affiliation(s)
- Telmo Henriques
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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Abstract
Upon binding to a promoter, RNA polymerase II can synthesize either a coding mRNA or a divergently transcribed noncoding RNA. In a recent issue of Science, Tan-Wong et al. (2012) find that intragenic looping increases the proper orientation of RNA polymerase II, reducing the production of divergent noncoding transcripts.
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Alzu A, Bermejo R, Begnis M, Lucca C, Piccini D, Carotenuto W, Saponaro M, Brambati A, Cocito A, Foiani M, Liberi G. Senataxin associates with replication forks to protect fork integrity across RNA-polymerase-II-transcribed genes. Cell 2013; 151:835-846. [PMID: 23141540 PMCID: PMC3494831 DOI: 10.1016/j.cell.2012.09.041] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 07/10/2012] [Accepted: 09/20/2012] [Indexed: 01/01/2023]
Abstract
Transcription hinders replication fork progression and stability. The ATR checkpoint and specialized DNA helicases assist DNA synthesis across transcription units to protect genome integrity. Combining genomic and genetic approaches together with the analysis of replication intermediates, we searched for factors coordinating replication with transcription. We show that the Sen1/Senataxin DNA/RNA helicase associates with forks, promoting their progression across RNA polymerase II (RNAPII)-transcribed genes. sen1 mutants accumulate aberrant DNA structures and DNA-RNA hybrids while forks clash head-on with RNAPII transcription units. These replication defects correlate with hyperrecombination and checkpoint activation in sen1 mutants. The Sen1 function at the forks is separable from its role in RNA processing. Our data, besides unmasking a key role for Senataxin in coordinating replication with transcription, provide a framework for understanding the pathological mechanisms caused by Senataxin deficiencies and leading to the severe neurodegenerative diseases ataxia with oculomotor apraxia type 2 and amyotrophic lateral sclerosis 4.
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Affiliation(s)
- Amaya Alzu
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Rodrigo Bermejo
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Martina Begnis
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Chiara Lucca
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Daniele Piccini
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Walter Carotenuto
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Marco Saponaro
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Alessandra Brambati
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy; Istituto di Genetica Molecolare del Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100 Pavia, Italy
| | - Andrea Cocito
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Marco Foiani
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy; DSBB-Università degli Studi di Milano, Via Celoria 26, 20139 Milan, Italy
| | - Giordano Liberi
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy; Istituto di Genetica Molecolare del Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100 Pavia, Italy.
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Nuclear pore complex composition: a new regulator of tissue-specific and developmental functions. Nat Rev Mol Cell Biol 2013; 13:687-99. [PMID: 23090414 DOI: 10.1038/nrm3461] [Citation(s) in RCA: 251] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Nuclear pore complexes (NPCs) are multiprotein aqueous channels that penetrate the nuclear envelope connecting the nucleus and the cytoplasm. NPCs consist of multiple copies of roughly 30 different proteins known as nucleoporins (NUPs). Due to their essential role in controlling nucleocytoplasmic transport, NPCs have traditionally been considered as structures of ubiquitous composition. The overall structure of the NPC is indeed conserved in all cells, but new evidence suggests that the protein composition of NPCs varies among cell types and tissues. Moreover, mutations in various nucleoporins result in tissue-specific diseases. These findings point towards a heterogeneity in NPC composition and function. This unexpected heterogeneity suggests that cells use a combination of different nucleoporins to assemble NPCs with distinct properties and specialized functions.
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Hsin JP, Manley JL. The RNA polymerase II CTD coordinates transcription and RNA processing. Genes Dev 2012; 26:2119-37. [PMID: 23028141 DOI: 10.1101/gad.200303.112] [Citation(s) in RCA: 463] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The C-terminal domain (CTD) of the RNA polymerase II largest subunit consists of multiple heptad repeats (consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), varying in number from 26 in yeast to 52 in vertebrates. The CTD functions to help couple transcription and processing of the nascent RNA and also plays roles in transcription elongation and termination. The CTD is subject to extensive post-translational modification, most notably phosphorylation, during the transcription cycle, which modulates its activities in the above processes. Therefore, understanding the nature of CTD modifications, including how they function and how they are regulated, is essential to understanding the mechanisms that control gene expression. While the significance of phosphorylation of Ser2 and Ser5 residues has been studied and appreciated for some time, several additional modifications have more recently been added to the CTD repertoire, and insight into their function has begun to emerge. Here, we review findings regarding modification and function of the CTD, highlighting the important role this unique domain plays in coordinating gene activity.
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Affiliation(s)
- Jing-Ping Hsin
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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