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Salari H, Fourel G, Jost D. Transcription regulates the spatio-temporal dynamics of genes through micro-compartmentalization. Nat Commun 2024; 15:5393. [PMID: 38918438 PMCID: PMC11199603 DOI: 10.1038/s41467-024-49727-7] [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: 07/24/2023] [Accepted: 06/17/2024] [Indexed: 06/27/2024] Open
Abstract
Although our understanding of the involvement of heterochromatin architectural factors in shaping nuclear organization is improving, there is still ongoing debate regarding the role of active genes in this process. In this study, we utilize publicly-available Micro-C data from mouse embryonic stem cells to investigate the relationship between gene transcription and 3D gene folding. Our analysis uncovers a nonmonotonic - globally positive - correlation between intragenic contact density and Pol II occupancy, independent of cohesin-based loop extrusion. Through the development of a biophysical model integrating the role of transcription dynamics within a polymer model of chromosome organization, we demonstrate that Pol II-mediated attractive interactions with limited valency between transcribed regions yield quantitative predictions consistent with chromosome-conformation-capture and live-imaging experiments. Our work provides compelling evidence that transcriptional activity shapes the 4D genome through Pol II-mediated micro-compartmentalization.
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Affiliation(s)
- Hossein Salari
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69007, Lyon, France.
- École Normale Supérieure de Lyon, CNRS, Laboratoire de Physique, 46 Allée d'Italie, 69007, Lyon, France.
| | - Geneviève Fourel
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69007, Lyon, France
| | - Daniel Jost
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69007, Lyon, France.
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2
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Hajiabadi H, Mamontova I, Prizak R, Pancholi A, Koziolek A, Hilbert L. Deep-learning microscopy image reconstruction with quality control reveals second-scale rearrangements in RNA polymerase II clusters. PNAS NEXUS 2022; 1:pgac065. [PMID: 36741438 PMCID: PMC9896941 DOI: 10.1093/pnasnexus/pgac065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/17/2022] [Indexed: 02/07/2023]
Abstract
Fluorescence microscopy, a central tool of biological research, is subject to inherent trade-offs in experiment design. For instance, image acquisition speed can only be increased in exchange for a lowered signal quality, or for an increased rate of photo-damage to the specimen. Computational denoising can recover some loss of signal, extending the trade-off margin for high-speed imaging. Recently proposed denoising on the basis of neural networks shows exceptional performance but raises concerns of errors typical of neural networks. Here, we present a work-flow that supports an empirically optimized reduction of exposure times, as well as per-image quality control to exclude images with reconstruction errors. We implement this work-flow on the basis of the denoising tool Noise2Void and assess the molecular state and 3D shape of RNA polymerase II (Pol II) clusters in live zebrafish embryos. Image acquisition speed could be tripled, achieving 2-s time resolution and 350-nm lateral image resolution. The obtained data reveal stereotyped events of approximately 10 s duration: initially, the molecular mark for recruited Pol II increases, then the mark for active Pol II increases, and finally Pol II clusters take on a stretched and unfolded shape. An independent analysis based on fixed sample images reproduces this sequence of events, and suggests that they are related to the transient association of genes with Pol II clusters. Our work-flow consists of procedures that can be implemented on commercial fluorescence microscopes without any hardware or software modification, and should, therefore, be transferable to many other applications.
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Affiliation(s)
| | | | - Roshan Prizak
- Institute of Biological and Chemical Systems, Department of Biological Information Processing, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
| | - Agnieszka Pancholi
- Institute of Biological and Chemical Systems, Department of Biological Information Processing, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
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3
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Coordination of transcription, processing, and export of highly expressed RNAs by distinct biomolecular condensates. Emerg Top Life Sci 2021; 4:281-291. [PMID: 32338276 PMCID: PMC7733674 DOI: 10.1042/etls20190160] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 04/01/2020] [Accepted: 04/06/2020] [Indexed: 12/30/2022]
Abstract
Genes under control of super-enhancers are expressed at extremely high levels and are frequently associated with nuclear speckles. Recent data suggest that the high concentration of unphosphorylated RNA polymerase II (Pol II) and Mediator recruited to super-enhancers create phase-separated condensates. Transcription initiates within or at the surface of these phase-separated droplets and the phosphorylation of Pol II, associated with transcription initiation and elongation, dissociates Pol II from these domains leading to engagement with nuclear speckles, which are enriched with RNA processing factors. The transitioning of Pol II from transcription initiation domains to RNA processing domains effectively co-ordinates transcription and processing of highly expressed RNAs which are then rapidly exported into the cytoplasm.
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4
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Ibragimov AN, Bylino OV, Shidlovskii YV. Molecular Basis of the Function of Transcriptional Enhancers. Cells 2020; 9:E1620. [PMID: 32635644 PMCID: PMC7407508 DOI: 10.3390/cells9071620] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/03/2020] [Accepted: 07/03/2020] [Indexed: 02/06/2023] Open
Abstract
Transcriptional enhancers are major genomic elements that control gene activity in eukaryotes. Recent studies provided deeper insight into the temporal and spatial organization of transcription in the nucleus, the role of non-coding RNAs in the process, and the epigenetic control of gene expression. Thus, multiple molecular details of enhancer functioning were revealed. Here, we describe the recent data and models of molecular organization of enhancer-driven transcription.
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Affiliation(s)
- Airat N. Ibragimov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (A.N.I.); (O.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia
| | - Oleg V. Bylino
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (A.N.I.); (O.V.B.)
| | - Yulii V. Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (A.N.I.); (O.V.B.)
- I.M. Sechenov First Moscow State Medical University, 8, bldg. 2 Trubetskaya St., 119048 Moscow, Russia
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5
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Cook PR, Marenduzzo D. Transcription-driven genome organization: a model for chromosome structure and the regulation of gene expression tested through simulations. Nucleic Acids Res 2019; 46:9895-9906. [PMID: 30239812 PMCID: PMC6212781 DOI: 10.1093/nar/gky763] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 09/14/2018] [Indexed: 12/29/2022] Open
Abstract
Current models for the folding of the human genome see a hierarchy stretching down from chromosome territories, through A/B compartments and topologically-associating domains (TADs), to contact domains stabilized by cohesin and CTCF. However, molecular mechanisms underlying this folding, and the way folding affects transcriptional activity, remain obscure. Here we review physical principles driving proteins bound to long polymers into clusters surrounded by loops, and present a parsimonious yet comprehensive model for the way the organization determines function. We argue that clusters of active RNA polymerases and their transcription factors are major architectural features; then, contact domains, TADs and compartments just reflect one or more loops and clusters. We suggest tethering a gene close to a cluster containing appropriate factors—a transcription factory—increases the firing frequency, and offer solutions to many current puzzles concerning the actions of enhancers, super-enhancers, boundaries and eQTLs (expression quantitative trait loci). As a result, the activity of any gene is directly influenced by the activity of other transcription units around it in 3D space, and this is supported by Brownian-dynamics simulations of transcription factors binding to cognate sites on long polymers.
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Affiliation(s)
- Peter R Cook
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Davide Marenduzzo
- SUPA, School of Physics, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
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6
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Heist T, Fukaya T, Levine M. Large distances separate coregulated genes in living Drosophila embryos. Proc Natl Acad Sci U S A 2019; 116:15062-15067. [PMID: 31285341 PMCID: PMC6660726 DOI: 10.1073/pnas.1908962116] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Transcriptional enhancers are short segments of DNA that switch genes on and off in response to a variety of cellular signals. Many enhancers map quite far from their target genes, on the order of tens or even hundreds of kilobases. There is extensive evidence that remote enhancers are brought into proximity with their target promoters via long-range looping interactions. However, the exact physical distances of these enhancer-promoter interactions remain uncertain. Here, we employ high-resolution imaging of living Drosophila embryos to visualize the distances separating linked genes that are coregulated by a shared enhancer. Cotransvection assays (linked genes on separate homologs) suggest a surprisingly large distance during transcriptional activity: at least 100-200 nm. Similar distances were observed when a shared enhancer was placed into close proximity with linked reporter genes in cis. These observations are consistent with the occurrence of "transcription hubs," whereby clusters (or condensates) of multiple RNA polymerase II complexes and associated cofactors are periodically recruited to active promoters. The dynamics of this process might be responsible for rapid fluctuations in the distances separating the transcription of coregulated reporter genes during transvection. We propose that enhancer-promoter communication depends on a combination of classical looping and linking models.
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Affiliation(s)
- Tyler Heist
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544
| | - Takashi Fukaya
- Institute for Quantitative Biosciences, The University of Tokyo, 113-0032 Tokyo, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 113-0032 Tokyo, Japan
| | - Michael Levine
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544;
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
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7
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Abstract
Fluorescence in situ hybridization (FISH) coupled to high-resolution microscopy is a powerful method for analyzing the subcellular localization of RNA. However, the detection of circular RNAs (circRNAs) using microscopy is challenging because the only feature of a circRNA that can be used for the probe design is its junction. Circular RNAs are expressed at varying levels, and for their efficient monitoring by FISH, background fluorescence levels need to be kept low. Here, we describe a FISH protocol coupled to high-precision localizations using a single fluorescently labeled probe spanning the circRNA junction; this allows circRNA detection in mammalian cells with high signal-to-noise ratios.
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Affiliation(s)
- Anne Zirkel
- Chromatin Systems Biology Laboratory, Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Argyris Papantonis
- Chromatin Systems Biology Laboratory, Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
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8
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Ryabichko SS, Ibragimov AN, Lebedeva LA, Kozlov EN, Shidlovskii YV. Super-Resolution Microscopy in Studying the Structure and Function of the Cell Nucleus. Acta Naturae 2017; 9:42-51. [PMID: 29340216 PMCID: PMC5762827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Indexed: 11/21/2022] Open
Abstract
In recent decades, novel microscopic methods commonly referred to as super- resolution microscopy have been developed. These methods enable the visualization of a cell with a resolution of up to 10 nm. The application of these methods is of great interest in studying the structure and function of the cell nucleus. The review describes the main achievements in this field.
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Affiliation(s)
- S. S. Ryabichko
- Institute of Gene Biology RAS, Vavilova Str. 34/5, Moscow, 119334, Russia
| | - A. N. Ibragimov
- Institute of Gene Biology RAS, Vavilova Str. 34/5, Moscow, 119334, Russia
| | - L. A. Lebedeva
- Institute of Gene Biology RAS, Vavilova Str. 34/5, Moscow, 119334, Russia
| | - E. N. Kozlov
- Institute of Gene Biology RAS, Vavilova Str. 34/5, Moscow, 119334, Russia
| | - Y. V. Shidlovskii
- Institute of Gene Biology RAS, Vavilova Str. 34/5, Moscow, 119334, Russia
- I.M. Sechenov First Moscow State Medical University, Trubetskaya Str. 8, bldg. 2, Moscow, 119048 , Russia
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9
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Higher-Order Chromatin Regulation of Inflammatory Gene Expression. Mediators Inflamm 2017; 2017:7848591. [PMID: 28490839 PMCID: PMC5401750 DOI: 10.1155/2017/7848591] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 03/21/2017] [Indexed: 12/14/2022] Open
Abstract
Whether it is caused by viruses and bacteria infection, or low-grade chronic inflammation of atherosclerosis and cellular senescence, the transcription factor (TF) NF-κB plays a central role in the inducible expression of inflammatory genes. Accumulated evidence has indicated that the chromatin environment is the main determinant of TF binding in gene expression regulation, including the stimulus-responsive NF-κB. Dynamic changes in intra- and interchromosomes are the key regulatory mechanisms promoting the binding of TFs. When an inflammatory process is triggered, NF-κB binds to enhancers or superenhancers, triggering the transcription of enhancer RNA (eRNA), driving the chromatin of the NF-κB-binding gene locus to construct transcriptional factories, and forming intra- or interchromosomal contacts. These processes reveal a mechanism in which intrachromosomal contacts appear to be cis-control enhancer-promoter communications, whereas interchromosomal regulatory elements construct trans-form relationships with genes on other chromosomes. This article will review emerging evidence on the genome organization hierarchy underlying the inflammatory response.
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10
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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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11
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Larkin JD, Cook PR. Super-resolution measurement of distance between transcription sites using RNA FISH with intronic probes. Methods 2016; 98:150-157. [PMID: 26564237 PMCID: PMC4819770 DOI: 10.1016/j.ymeth.2015.11.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 11/05/2015] [Accepted: 11/08/2015] [Indexed: 11/06/2022] Open
Abstract
Label intronic RNA using FISH to identify sites of transcription by RNA polymerase II. Low-tech microscopes are used to acquire images for super-resolution measurements. Distances between sites of transcription are determined with precision near 20 nm. Spatial-temporal relationships between active genes are studied with this method.
Nascent transcripts being copied from specific human genes can be detected using RNA FISH (fluorescence in situ hybridization) with intronic probes, and the distance between two different nascent transcripts is often measured when studying structure–function relationships. Such distance measurements are limited by the resolution of the light microscope. Here we describe methods for measuring these distances in cultured cells with a precision of a few tens of nanometers, using equipment found in most laboratories (i.e., a wide-field fluorescence microscope equipped with a charged-coupled-device camera). Using images of pairs of transcripts that are often co-transcribed, we discuss how selection of cell type, design of FISH probes, image acquisition, and image processing affect the precision that can be achieved.
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Affiliation(s)
- Joshua D Larkin
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Peter R Cook
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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12
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Dekker J, Mirny L. The 3D Genome as Moderator of Chromosomal Communication. Cell 2016; 164:1110-1121. [PMID: 26967279 PMCID: PMC4788811 DOI: 10.1016/j.cell.2016.02.007] [Citation(s) in RCA: 592] [Impact Index Per Article: 74.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 01/22/2016] [Accepted: 02/01/2016] [Indexed: 02/07/2023]
Abstract
Proper expression of genes requires communication with their regulatory elements that can be located elsewhere along the chromosome. The physics of chromatin fibers imposes a range of constraints on such communication. The molecular and biophysical mechanisms by which chromosomal communication is established, or prevented, have become a topic of intense study, and important roles for the spatial organization of chromosomes are being discovered. Here we present a view of the interphase 3D genome characterized by extensive physical compartmentalization and insulation on the one hand and facilitated long-range interactions on the other. We propose the existence of topological machines dedicated to set up and to exploit a 3D genome organization to both promote and censor communication along and between chromosomes.
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Affiliation(s)
- Job Dekker
- Howard Hughes Medical Institute, Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605-0103, USA.
| | - Leonid Mirny
- Institute for Medical Engineering and Science and Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, E25-526C, Cambridge, MA 02139, USA.
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13
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Abstract
The role of genome architecture in transcription regulation has become the focus of an increasing number of studies over the past decade. Chromatin organization can have a significant impact on gene expression by promoting or restricting the physical proximity between regulatory DNA elements. Given that any change in chromatin state has the potential to alter DNA folding and the proximity between control elements, the spatial organization of chromatin is inherently linked to its molecular composition. In this review, we explore how modulators of chromatin state and organization might keep gene expression in check. We discuss recent findings and present some of the less well-studied aspects of spatial genome organization such as chromatin dynamics and regulation by non-coding RNAs.
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14
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Golov AK, Gavrilov AA, Razin SV. The Role of Crowding Forces in Juxtaposing β-Globin Gene Domain Remote Regulatory Elements in Mouse Erythroid Cells. PLoS One 2015; 10:e0139855. [PMID: 26436546 PMCID: PMC4593578 DOI: 10.1371/journal.pone.0139855] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/11/2015] [Indexed: 01/03/2023] Open
Abstract
The extremely high concentration of macromolecules in a eukaryotic cell nucleus indicates that the nucleoplasm is a crowded macromolecular solution in which large objects tend to gather together due to crowding forces. It has been shown experimentally that crowding forces support the integrity of various nuclear compartments. However, little is known about their role in control of chromatin dynamics in vivo. Here, we experimentally addressed the possible role of crowding forces in spatial organization of the eukaryotic genome. Using the mouse β-globin domain as a model, we demonstrated that spatial juxtaposition of the remote regulatory elements of this domain in globin-expressing cells may be lost and restored by manipulation of the level of macromolecular crowding. In addition to proving the role of crowding forces in shaping interphase chromatin, our results suggest that the folding of the chromatin fiber is a major determinant in juxtaposing remote genomic elements.
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Affiliation(s)
- Arkadiy K. Golov
- Institute of Gene Biology of the Russian Academy of Sciences, Vavilov Street 34/5, 119334, Moscow, Russia
| | - Alexey A. Gavrilov
- Institute of Gene Biology of the Russian Academy of Sciences, Vavilov Street 34/5, 119334, Moscow, Russia
| | - Sergey V. Razin
- Institute of Gene Biology of the Russian Academy of Sciences, Vavilov Street 34/5, 119334, Moscow, Russia
- Molecular Biology Department, Biological Faculty, Lomonosov Moscow State University, 119992, Moscow, Russia
- * E-mail:
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15
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Feuerborn A, Cook PR. Why the activity of a gene depends on its neighbors. Trends Genet 2015; 31:483-90. [PMID: 26259670 DOI: 10.1016/j.tig.2015.07.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 06/25/2015] [Accepted: 07/15/2015] [Indexed: 11/15/2022]
Abstract
Sixty years ago, the position of a gene on a chromosome was seen to be a major determinant of gene activity; however, position effects are rarely central to current discussions of gene expression. We describe a comprehensive and simplifying view of how position in 1D sequence and 3D nuclear space underlies expression. We suggest that apparently-different regulatory motifs including enhancers, silencers, insulators, barriers, and boundaries act similarly - they are active promoters that tether target genes close to, or distant from, appropriate transcription sites or 'factories'. We also suggest that any active transcription unit regulates the firing of its neighbors - and thus can be categorized as one or other type of motif; this is consistent with expression quantitative trait loci (eQTLs) being widely dispersed.
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Affiliation(s)
- Alexander Feuerborn
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Peter R Cook
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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16
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Kelly S, Georgomanolis T, Zirkel A, Diermeier S, O'Reilly D, Murphy S, Längst G, Cook PR, Papantonis A. Splicing of many human genes involves sites embedded within introns. Nucleic Acids Res 2015; 43:4721-32. [PMID: 25897131 PMCID: PMC4482092 DOI: 10.1093/nar/gkv386] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 04/12/2015] [Indexed: 02/03/2023] Open
Abstract
The conventional model for splicing involves excision of each intron in one piece; we demonstrate this inaccurately describes splicing in many human genes. First, after switching on transcription of SAMD4A, a gene with a 134 kb-long first intron, splicing joins the 3′ end of exon 1 to successive points within intron 1 well before the acceptor site at exon 2 is made. Second, genome-wide analysis shows that >60% of active genes yield products generated by such intermediate intron splicing. These products are present at ∼15% the levels of primary transcripts, are encoded by conserved sequences similar to those found at canonical acceptors, and marked by distinctive structural and epigenetic features. Finally, using targeted genome editing, we demonstrate that inhibiting the formation of these splicing intermediates affects efficient exon–exon splicing. These findings greatly expand the functional and regulatory complexity of the human transcriptome.
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Affiliation(s)
- Steven Kelly
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | | | - Anne Zirkel
- Centre for Molecular Medicine, University of Cologne, Cologne D-50931, Germany
| | - Sarah Diermeier
- Institut für Biochemie III, University of Regensburg, Regensburg D-93053, Germany
| | - Dawn O'Reilly
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Gernot Längst
- Institut für Biochemie III, University of Regensburg, Regensburg D-93053, Germany
| | - Peter R Cook
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Argyris Papantonis
- Centre for Molecular Medicine, University of Cologne, Cologne D-50931, Germany
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17
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Erdel F, Baum M, Rippe K. The viscoelastic properties of chromatin and the nucleoplasm revealed by scale-dependent protein mobility. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:064115. [PMID: 25563347 DOI: 10.1088/0953-8984/27/6/064115] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The eukaryotic cell nucleus harbours the DNA genome that is organized in a dynamic chromatin network and embedded in a viscous crowded fluid. This environment directly affects enzymatic reactions and target search processes that access the DNA sequence information. However, its physical properties as a reaction medium are poorly understood. Here, we exploit mobility measurements of differently sized inert green fluorescent tracer proteins to characterize the viscoelastic properties of the nuclear interior of a living human cell. We find that it resembles a viscous fluid on small and large scales but appears viscoelastic on intermediate scales that change with protein size. Our results are consistent with simulations of diffusion through polymers and suggest that chromatin forms a random obstacle network rather than a self-similar structure with fixed fractal dimensions. By calculating how long molecules remember their previous position in dependence on their size, we evaluate how the nuclear environment affects search processes of chromatin targets.
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Affiliation(s)
- Fabian Erdel
- Deutsches Krebsforschungszentrum (DKFZ) and BioQuant, Research Group Genome Organization & Function, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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18
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Ulianov SV, Gavrilov AA, Razin SV. Nuclear Compartments, Genome Folding, and Enhancer-Promoter Communication. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:183-244. [DOI: 10.1016/bs.ircmb.2014.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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19
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Habuchi S. Super-resolution molecular and functional imaging of nanoscale architectures in life and materials science. Front Bioeng Biotechnol 2014; 2:20. [PMID: 25152893 PMCID: PMC4126472 DOI: 10.3389/fbioe.2014.00020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 05/30/2014] [Indexed: 11/13/2022] Open
Abstract
Super-resolution (SR) fluorescence microscopy has been revolutionizing the way in which we investigate the structures, dynamics, and functions of a wide range of nanoscale systems. In this review, I describe the current state of various SR fluorescence microscopy techniques along with the latest developments of fluorophores and labeling for the SR microscopy. I discuss the applications of SR microscopy in the fields of life science and materials science with a special emphasis on quantitative molecular imaging and nanoscale functional imaging. These studies open new opportunities for unraveling the physical, chemical, and optical properties of a wide range of nanoscale architectures together with their nanostructures and will enable the development of new (bio-)nanotechnology.
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Affiliation(s)
- Satoshi Habuchi
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology , Jeddah , Saudi Arabia
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20
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Tai PWL, Zaidi SK, Wu H, Grandy RA, Montecino MM, van Wijnen AJ, Lian JB, Stein GS, Stein JL. The dynamic architectural and epigenetic nuclear landscape: developing the genomic almanac of biology and disease. J Cell Physiol 2014; 229:711-27. [PMID: 24242872 PMCID: PMC3996806 DOI: 10.1002/jcp.24508] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 11/11/2013] [Indexed: 12/31/2022]
Abstract
Compaction of the eukaryotic genome into the confined space of the cell nucleus must occur faithfully throughout each cell cycle to retain gene expression fidelity. For decades, experimental limitations to study the structural organization of the interphase nucleus restricted our understanding of its contributions towards gene regulation and disease. However, within the past few years, our capability to visualize chromosomes in vivo with sophisticated fluorescence microscopy, and to characterize chromosomal regulatory environments via massively parallel sequencing methodologies have drastically changed how we currently understand epigenetic gene control within the context of three-dimensional nuclear structure. The rapid rate at which information on nuclear structure is unfolding brings challenges to compare and contrast recent observations with historic findings. In this review, we discuss experimental breakthroughs that have influenced how we understand and explore the dynamic structure and function of the nucleus, and how we can incorporate historical perspectives with insights acquired from the ever-evolving advances in molecular biology and pathology.
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Affiliation(s)
- Phillip W. L. Tai
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Sayyed K. Zaidi
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Hai Wu
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Rodrigo A. Grandy
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Martin M. Montecino
- Center for Biomedical Research and FONDAP Center for Genome Regulation, Universidad Andres Bello, Santiago, Chile
| | - André J. van Wijnen
- Departments of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN
| | - Jane B. Lian
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Gary S. Stein
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
| | - Janet L. Stein
- Department of Biochemistry and Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT
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21
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Benedetti F, Dorier J, Burnier Y, Stasiak A. Models that include supercoiling of topological domains reproduce several known features of interphase chromosomes. Nucleic Acids Res 2013; 42:2848-55. [PMID: 24366878 PMCID: PMC3950722 DOI: 10.1093/nar/gkt1353] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Understanding the structure of interphase chromosomes is essential to elucidate regulatory mechanisms of gene expression. During recent years, high-throughput DNA sequencing expanded the power of chromosome conformation capture (3C) methods that provide information about reciprocal spatial proximity of chromosomal loci. Since 2012, it is known that entire chromatin in interphase chromosomes is organized into regions with strongly increased frequency of internal contacts. These regions, with the average size of ∼1 Mb, were named topological domains. More recent studies demonstrated presence of unconstrained supercoiling in interphase chromosomes. Using Brownian dynamics simulations, we show here that by including supercoiling into models of topological domains one can reproduce and thus provide possible explanations of several experimentally observed characteristics of interphase chromosomes, such as their complex contact maps.
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Affiliation(s)
- Fabrizio Benedetti
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland, Vital-IT Group, SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland and Laboratory of Particle Physics and Cosmology, Institute of Theoretical Physics, Ecole polytechnique fédérale de Lausanne EPFL, 1015 Lausanne, Switzerland
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22
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Papantonis A, Cook PR. Transcription factories: genome organization and gene regulation. Chem Rev 2013; 113:8683-705. [PMID: 23597155 DOI: 10.1021/cr300513p] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Argyris Papantonis
- Sir William Dunn School of Pathology, University of Oxford , South Parks Road, Oxford OX1 3RE, United Kingdom
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