1
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Lando D, Ma X, Cao Y, Jartseva A, Stevens TJ, Boucher W, Reynolds N, Montibus B, Hall D, Lackner A, Ragheb R, Leeb M, Hendrich BD, Laue ED. Enhancer-promoter interactions are reconfigured through the formation of long-range multiway hubs as mouse ES cells exit pluripotency. Mol Cell 2024; 84:1406-1421.e8. [PMID: 38490199 PMCID: PMC7616059 DOI: 10.1016/j.molcel.2024.02.015] [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: 02/02/2023] [Revised: 12/19/2023] [Accepted: 02/14/2024] [Indexed: 03/17/2024]
Abstract
Enhancers bind transcription factors, chromatin regulators, and non-coding transcripts to modulate the expression of target genes. Here, we report 3D genome structures of single mouse ES cells as they are induced to exit pluripotency and transition through a formative stage prior to undergoing neuroectodermal differentiation. We find that there is a remarkable reorganization of 3D genome structure where inter-chromosomal intermingling increases dramatically in the formative state. This intermingling is associated with the formation of a large number of multiway hubs that bring together enhancers and promoters with similar chromatin states from typically 5-8 distant chromosomal sites that are often separated by many Mb from each other. In the formative state, genes important for pluripotency exit establish contacts with emerging enhancers within these multiway hubs, suggesting that the structural changes we have observed may play an important role in modulating transcription and establishing new cell identities.
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Affiliation(s)
- David Lando
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Xiaoyan Ma
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Yang Cao
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | | | - Tim J Stevens
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Wayne Boucher
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Nicola Reynolds
- Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, UK
| | - Bertille Montibus
- Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, UK
| | - Dominic Hall
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK; Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, UK
| | - Andreas Lackner
- Max Perutz Laboratories Vienna, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Ramy Ragheb
- Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, UK
| | - Martin Leeb
- Max Perutz Laboratories Vienna, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Brian D Hendrich
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK; Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, UK.
| | - Ernest D Laue
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK; Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, UK.
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2
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Oberbeckmann E, Quililan K, Cramer P, Oudelaar AM. In vitro reconstitution of chromatin domains shows a role for nucleosome positioning in 3D genome organization. Nat Genet 2024; 56:483-492. [PMID: 38291333 PMCID: PMC10937381 DOI: 10.1038/s41588-023-01649-8] [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: 03/30/2023] [Accepted: 12/15/2023] [Indexed: 02/01/2024]
Abstract
Eukaryotic genomes are organized into chromatin domains. The molecular mechanisms driving the formation of these domains are difficult to dissect in vivo and remain poorly understood. Here we reconstitute Saccharomyces cerevisiae chromatin in vitro and determine its 3D organization at subnucleosome resolution by micrococcal nuclease-based chromosome conformation capture and molecular dynamics simulations. We show that regularly spaced and phased nucleosome arrays form chromatin domains in vitro that resemble domains in vivo. This demonstrates that neither loop extrusion nor transcription is required for basic domain formation in yeast. In addition, we find that the boundaries of reconstituted domains correspond to nucleosome-free regions and that insulation strength scales with their width. Finally, we show that domain compaction depends on nucleosome linker length, with longer linkers forming more compact structures. Together, our results demonstrate that regular nucleosome positioning is important for the formation of chromatin domains and provide a proof-of-principle for bottom-up 3D genome studies.
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Affiliation(s)
- Elisa Oberbeckmann
- Max Planck Institute for Multidisciplinary Sciences, Department of Molecular Biology, Göttingen, Germany.
| | - Kimberly Quililan
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany
- The Francis Crick Institute, London, UK
| | - Patrick Cramer
- Max Planck Institute for Multidisciplinary Sciences, Department of Molecular Biology, Göttingen, Germany
| | - A Marieke Oudelaar
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany.
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3
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Iida S, Ide S, Tamura S, Tani T, Goto T, Shribak M, Maeshima K. Orientation-Independent-DIC imaging reveals that a transient rise in depletion force contributes to mitotic chromosome condensation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.11.566679. [PMID: 37986866 PMCID: PMC10659371 DOI: 10.1101/2023.11.11.566679] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Genomic information must be faithfully transmitted into two daughter cells during mitosis. To ensure the transmission process, interphase chromatin is further condensed into mitotic chromosomes. Although protein factors like condensins and topoisomerase IIα are involved in the assembly of mitotic chromosomes, the physical bases of the condensation process remain unclear. Depletion force/macromolecular crowding, an effective attractive force that arises between large structures in crowded environments around chromosomes, may contribute to the condensation process. To approach this issue, we investigated the "chromosome milieu" during mitosis of living human cells using orientation-independent-differential interference contrast (OI-DIC) module combined with a confocal laser scanning microscope, which is capable of precisely mapping optical path differences and estimating molecular densities. We found that the molecular density surrounding chromosomes increased with the progression from prometaphase to anaphase, concurring with chromosome condensation. However, the molecular density went down in telophase, when chromosome decondensation began. Changes in the molecular density around chromosomes by hypotonic or hypertonic treatment consistently altered the condensation levels of chromosomes. In vitro, native chromatin was converted into liquid droplets of chromatin in the presence of cations and a macromolecular crowder. Additional crowder made the chromatin droplets stiffer and more solid-like, with further condensation. These results suggest that a transient rise in depletion force, likely triggered by the relocation of macromolecules (proteins, RNAs and others) via nuclear envelope breakdown and also by a subsequent decrease in cell-volumes, contributes to mitotic chromosome condensation, shedding light on a new aspect of the condensation mechanism in living human cells.
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Affiliation(s)
- Shiori Iida
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
| | - Satoru Ide
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
| | - Sachiko Tamura
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Tomomi Tani
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan
| | - Tatsuhiko Goto
- Research Center for Global Agromedicine and Department of Life and Food Sciences, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Michael Shribak
- Marine Biological Laboratory, 7 MBL St, Woods Hole, MA 02543, USA
| | - Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
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4
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Serizay J, Matthey-Doret C, Bignaud A, Baudry L, Koszul R. Orchestrating chromosome conformation capture analysis with Bioconductor. Nat Commun 2024; 15:1072. [PMID: 38316789 PMCID: PMC10844600 DOI: 10.1038/s41467-024-44761-x] [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: 09/02/2023] [Accepted: 12/28/2023] [Indexed: 02/07/2024] Open
Abstract
Genome-wide chromatin conformation capture assays provide formidable insights into the spatial organization of genomes. However, due to the complexity of the data structure, their integration in multi-omics workflows remains challenging. We present data structures, computational methods and visualization tools available in Bioconductor to investigate Hi-C, micro-C and other 3C-related data, in R. An online book ( https://bioconductor.org/books/OHCA/ ) further provides prospective end users with a number of workflows to process, import, analyze and visualize any type of chromosome conformation capture data.
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Affiliation(s)
- Jacques Serizay
- Institut Pasteur, CNRS UMR3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France.
| | - Cyril Matthey-Doret
- Institut Pasteur, CNRS UMR3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
- Sorbonne Université, Collège Doctoral, Paris, France
- Swiss Data Science Center, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - Amaury Bignaud
- Institut Pasteur, CNRS UMR3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
- Sorbonne Université, Collège Doctoral, Paris, France
| | - Lyam Baudry
- Institut Pasteur, CNRS UMR3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
- Sorbonne Université, Collège Doctoral, Paris, France
- Université de Lausanne, Center for Integrative Genomics, Quartier Sorge, 1015, Lausanne, Switzerland
| | - Romain Koszul
- Institut Pasteur, CNRS UMR3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
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5
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Hung TC, Kingsley DM, Boettiger AN. Boundary stacking interactions enable cross-TAD enhancer-promoter communication during limb development. Nat Genet 2024; 56:306-314. [PMID: 38238628 DOI: 10.1038/s41588-023-01641-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 12/06/2023] [Indexed: 02/15/2024]
Abstract
Although promoters and their enhancers are frequently contained within a topologically associating domain (TAD), some developmentally important genes have their promoter and enhancers within different TADs. Hypotheses about molecular mechanisms enabling cross-TAD interactions remain to be assessed. To test these hypotheses, we used optical reconstruction of chromatin architecture to characterize the conformations of the Pitx1 locus on single chromosomes in developing mouse limbs. Our data support a model in which neighboring boundaries are stacked as a result of loop extrusion, bringing boundary-proximal cis-elements into contact. This stacking interaction also contributes to the appearance of architectural stripes in the population average maps. Through molecular dynamics simulations, we found that increasing boundary strengths facilitates the formation of the stacked boundary conformation, counter-intuitively facilitating border bypass. This work provides a revised view of the TAD borders' function, both facilitating and preventing cis-regulatory interactions, and introduces a framework to distinguish border-crossing from border-respecting enhancer-promoter pairs.
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Affiliation(s)
- Tzu-Chiao Hung
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - David M Kingsley
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Alistair N Boettiger
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.
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6
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Lin X, Zhang B. Explicit ion modeling predicts physicochemical interactions for chromatin organization. eLife 2024; 12:RP90073. [PMID: 38289342 PMCID: PMC10945522 DOI: 10.7554/elife.90073] [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] [Indexed: 09/01/2023] Open
Abstract
Molecular mechanisms that dictate chromatin organization in vivo are under active investigation, and the extent to which intrinsic interactions contribute to this process remains debatable. A central quantity for evaluating their contribution is the strength of nucleosome-nucleosome binding, which previous experiments have estimated to range from 2 to 14 kBT. We introduce an explicit ion model to dramatically enhance the accuracy of residue-level coarse-grained modeling approaches across a wide range of ionic concentrations. This model allows for de novo predictions of chromatin organization and remains computationally efficient, enabling large-scale conformational sampling for free energy calculations. It reproduces the energetics of protein-DNA binding and unwinding of single nucleosomal DNA, and resolves the differential impact of mono- and divalent ions on chromatin conformations. Moreover, we showed that the model can reconcile various experiments on quantifying nucleosomal interactions, providing an explanation for the large discrepancy between existing estimations. We predict the interaction strength at physiological conditions to be 9 kBT, a value that is nonetheless sensitive to DNA linker length and the presence of linker histones. Our study strongly supports the contribution of physicochemical interactions to the phase behavior of chromatin aggregates and chromatin organization inside the nucleus.
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Affiliation(s)
- Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
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7
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Du M, Stitzinger SH, Spille JH, Cho WK, Lee C, Hijaz M, Quintana A, Cissé II. Direct observation of a condensate effect on super-enhancer controlled gene bursting. Cell 2024; 187:331-344.e17. [PMID: 38194964 DOI: 10.1016/j.cell.2023.12.005] [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: 05/09/2023] [Revised: 10/29/2023] [Accepted: 12/04/2023] [Indexed: 01/11/2024]
Abstract
Enhancers are distal DNA elements believed to loop and contact promoters to control gene expression. Recently, we found diffraction-sized transcriptional condensates at genes controlled by clusters of enhancers (super-enhancers). However, a direct function of endogenous condensates in controlling gene expression remains elusive. Here, we develop live-cell super-resolution and multi-color 3D-imaging approaches to investigate putative roles of endogenous condensates in the regulation of super-enhancer controlled gene Sox2. In contrast to enhancer distance, we find instead that the condensate's positional dynamics are a better predictor of gene expression. A basal gene bursting occurs when the condensate is far (>1 μm), but burst size and frequency are enhanced when the condensate moves in proximity (<1 μm). Perturbations of cohesin and local DNA elements do not prevent basal bursting but affect the condensate and its burst enhancement. We propose a three-way kissing model whereby the condensate interacts transiently with gene locus and regulatory DNA elements to control gene bursting.
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Affiliation(s)
- Manyu Du
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Simon Hendrik Stitzinger
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Jan-Hendrik Spille
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Won-Ki Cho
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Choongman Lee
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Mohammed Hijaz
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Andrea Quintana
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Ibrahim I Cissé
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany.
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8
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Seelbinder B, Wagner S, Jain M, Erben E, Klykov S, Stoev ID, Krishnaswamy VR, Kreysing M. Probe-free optical chromatin deformation and measurement of differential mechanical properties in the nucleus. eLife 2024; 13:e76421. [PMID: 38214505 PMCID: PMC10786458 DOI: 10.7554/elife.76421] [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: 12/15/2021] [Accepted: 11/29/2023] [Indexed: 01/13/2024] Open
Abstract
The nucleus is highly organized to facilitate coordinated gene transcription. Measuring the rheological properties of the nucleus and its sub-compartments will be crucial to understand the principles underlying nuclear organization. Here, we show that strongly localized temperature gradients (approaching 1°C/µm) can lead to substantial intra-nuclear chromatin displacements (>1 µm), while nuclear area and lamina shape remain unaffected. Using particle image velocimetry (PIV), intra-nuclear displacement fields can be calculated and converted into spatio-temporally resolved maps of various strain components. Using this approach, we show that chromatin displacements are highly reversible, indicating that elastic contributions are dominant in maintaining nuclear organization on the time scale of seconds. In genetically inverted nuclei, centrally compacted heterochromatin displays high resistance to deformation, giving a rigid, solid-like appearance. Correlating spatially resolved strain maps with fluorescent reporters in conventional interphase nuclei reveals that various nuclear compartments possess distinct mechanical identities. Surprisingly, both densely and loosely packed chromatin showed high resistance to deformation, compared to medium dense chromatin. Equally, nucleoli display particularly high resistance and strong local anchoring to heterochromatin. Our results establish how localized temperature gradients can be used to drive nuclear compartments out of mechanical equilibrium to obtain spatial maps of their material responses.
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Affiliation(s)
- Benjamin Seelbinder
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Centre for Systems BiologyDresdenGermany
| | - Susan Wagner
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Institute of Biological and Chemical Systems-Biological Information Processing, Karlsruhe Institute of TechnologyEggenstein-LeopoldshafenGermany
| | - Manavi Jain
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Centre for Systems BiologyDresdenGermany
| | - Elena Erben
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Centre for Systems BiologyDresdenGermany
| | - Sergei Klykov
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Centre for Systems BiologyDresdenGermany
| | - Iliya Dimitrov Stoev
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Centre for Systems BiologyDresdenGermany
| | | | - Moritz Kreysing
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Centre for Systems BiologyDresdenGermany
- Institute of Biological and Chemical Systems-Biological Information Processing, Karlsruhe Institute of TechnologyEggenstein-LeopoldshafenGermany
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9
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Laghmach R, Di Pierro M, Potoyan DA. Four-Dimensional Mesoscale Liquid Model of Nucleus Resolves Chromatin's Radial Organization. PRX LIFE 2024; 2:013006. [PMID: 38601142 PMCID: PMC11005002 DOI: 10.1103/prxlife.2.013006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Recent advances chromatin capture, imaging techniques, and polymer modeling have dramatically enhanced quantitative understanding of chromosomal folding. However, the dynamism inherent in genome architectures due to physical and biochemical forces and their impact on nuclear architecture and cellular functions remains elusive. While imaging of chromatin in four dimensions is becoming more common, there is a conspicuous lack of physics-based computational tools appropriate for revealing the forces that shape nuclear architecture and dynamics. To this end, we have developed a multiphase liquid model of the nucleus, which can resolve chromosomal territories, compartments, and nuclear lamina using a physics-based and data-informed free-energy function. The model enables rapid hypothesis-driven prototyping of nuclear dynamics in four dimensions, thereby facilitating comparison with whole nucleus imaging experiments. As an application, we model the Drosophila nucleus and map phase diagram of various possible nuclear morphologies. We shed light on the interplay of adhesive and cohesive interactions which give rise to distinct radial organization seen in conventional, inverted, and senescent nuclear architectures. The results also show the highly dynamic nature of the radial organization, the disruption of which leads to significant variability in domain coarsening dynamics and consequently variability of chromatin architecture. The model also highlights the impact of oblate nuclear geometry and heterochromatin-subtype interactions on the global chromatin architecture and local asymmetry of chromatin compartments.
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Affiliation(s)
- Rabia Laghmach
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | - Michele Di Pierro
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Davit A. Potoyan
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA and Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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10
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Ge X, Huang H, Han K, Xu W, Wang Z, Wu Q. Outward-oriented sites within clustered CTCF boundaries are key for intra-TAD chromatin interactions and gene regulation. Nat Commun 2023; 14:8101. [PMID: 38062010 PMCID: PMC10703910 DOI: 10.1038/s41467-023-43849-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
CTCF plays an important role in 3D genome organization by adjusting the strength of chromatin insulation at TAD boundaries, where clustered CBS (CTCF-binding site) elements are often arranged in a tandem array with a complex divergent or convergent orientation. Here, using Pcdh and HOXD loci as a paradigm, we look into the clustered CTCF TAD boundaries and find that, counterintuitively, outward-oriented CBS elements are crucial for inward enhancer-promoter interactions as well as for gene regulation. Specifically, by combinatorial deletions of a series of putative enhancer elements in mice in vivo or CBS elements in cultured cells in vitro, in conjunction with chromosome conformation capture and RNA-seq analyses, we show that deletions of outward-oriented CBS elements weaken the strength of long-distance intra-TAD promoter-enhancer interactions and enhancer activation of target genes. Our data highlight the crucial role of outward-oriented CBS elements within the clustered CTCF TAD boundaries in developmental gene regulation and have interesting implications on the organization principles of clustered CTCF sites within TAD boundaries.
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Affiliation(s)
- Xiao Ge
- Center for Comparative Biomedicine, Ministry of Education Key Laboratory of Systems Biomedicine, State Key Laboratory of Systems Medicine for Cancer, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Institute of Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
- WLA Laboratories, Shanghai, 201203, China
| | - Haiyan Huang
- Center for Comparative Biomedicine, Ministry of Education Key Laboratory of Systems Biomedicine, State Key Laboratory of Systems Medicine for Cancer, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Institute of Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
- WLA Laboratories, Shanghai, 201203, China
| | - Keqi Han
- Center for Comparative Biomedicine, Ministry of Education Key Laboratory of Systems Biomedicine, State Key Laboratory of Systems Medicine for Cancer, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Institute of Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
- WLA Laboratories, Shanghai, 201203, China
| | - Wangjie Xu
- Laboratory Animal Center, Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhaoxia Wang
- Laboratory Animal Center, Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Qiang Wu
- Center for Comparative Biomedicine, Ministry of Education Key Laboratory of Systems Biomedicine, State Key Laboratory of Systems Medicine for Cancer, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Institute of Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China.
- WLA Laboratories, Shanghai, 201203, China.
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11
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Lin X, Zhang B. Explicit Ion Modeling Predicts Physicochemical Interactions for Chromatin Organization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.16.541030. [PMID: 37293007 PMCID: PMC10245791 DOI: 10.1101/2023.05.16.541030] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Molecular mechanisms that dictate chromatin organization in vivo are under active investigation, and the extent to which intrinsic interactions contribute to this process remains debatable. A central quantity for evaluating their contribution is the strength of nucleosome-nucleosome binding, which previous experiments have estimated to range from 2 to 14 kBT. We introduce an explicit ion model to dramatically enhance the accuracy of residue-level coarse-grained modeling approaches across a wide range of ionic concentrations. This model allows for de novo predictions of chromatin organization and remains computationally efficient, enabling large-scale conformational sampling for free energy calculations. It reproduces the energetics of protein-DNA binding and unwinding of single nucleosomal DNA, and resolves the differential impact of mono and divalent ions on chromatin conformations. Moreover, we showed that the model can reconcile various experiments on quantifying nucleosomal interactions, providing an explanation for the large discrepancy between existing estimations. We predict the interaction strength at physiological conditions to be 9 kBT, a value that is nonetheless sensitive to DNA linker length and the presence of linker histones. Our study strongly supports the contribution of physicochemical interactions to the phase behavior of chromatin aggregates and chromatin organization inside the nucleus.
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Affiliation(s)
- Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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12
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Capelson M. You are who your friends are-nuclear pore proteins as components of chromatin-binding complexes. FEBS Lett 2023; 597:2769-2781. [PMID: 37652464 PMCID: PMC11081553 DOI: 10.1002/1873-3468.14728] [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: 07/31/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 09/02/2023]
Abstract
Nuclear pore complexes are large multicomponent protein complexes that are embedded in the nuclear envelope, where they mediate nucleocytoplasmic transport. In addition to supporting transport, nuclear pore components, termed nucleoporins (Nups), can interact with chromatin and influence genome function. A subset of Nups can also localize to the nuclear interior and bind chromatin intranuclearly, providing an opportunity to investigate chromatin-associated functions of Nups outside of the transport context. This review focuses on the gene regulatory functions of such intranuclear Nups, with a particular emphasis on their identity as components of several chromatin regulatory complexes. Recent proteomic screens have identified Nups as interacting partners of active and repressive epigenetic machinery, architectural proteins, and DNA replication complexes, providing insight into molecular mechanisms via which Nups regulate gene expression programs. This review summarizes these interactions and discusses their potential functions in the broader framework of nuclear genome organization.
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Affiliation(s)
- Maya Capelson
- Cell and Molecular Biology Program, Department of Biology, San Diego State University, CA, USA
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13
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Yáñez-Cuna FO, Koszul R. Insights in bacterial genome folding. Curr Opin Struct Biol 2023; 82:102679. [PMID: 37604045 DOI: 10.1016/j.sbi.2023.102679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 08/23/2023]
Abstract
Chromosomes in all domains of life are well-defined structural entities with complex hierarchical organization. The regulation of this hierarchical organization and its functional interplay with gene expression or other chromosome metabolic processes such as repair, replication, or segregation is actively investigated in a variety of species, including prokaryotes. Bacterial chromosomes are typically gene-dense with few non-coding sequences and are organized into the nucleoid, a membrane-less compartment composed of DNA, RNA, and proteins (nucleoid-associated proteins or NAPs). The continuous improvement of imaging and genomic methods has put the organization of these Mb-long molecules at reach, allowing to disambiguate some of their highly dynamic properties and intertwined structural features. Here we review and discuss some of the recent advances in the field of bacterial chromosome organization.
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Affiliation(s)
- Fares Osam Yáñez-Cuna
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, 75015, Paris, France
| | - Romain Koszul
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, 75015, Paris, France.
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14
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Polovnikov KE, Slavov B, Belan S, Imakaev M, Brandão HB, Mirny LA. Crumpled polymer with loops recapitulates key features of chromosome organization. PHYSICAL REVIEW. X 2023; 13:041029. [PMID: 38774252 PMCID: PMC11108028 DOI: 10.1103/physrevx.13.041029] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/24/2024]
Abstract
Chromosomes are exceedingly long topologically-constrained polymers compacted in a cell nucleus. We recently suggested that chromosomes are organized into loops by an active process of loop extrusion. Yet loops remain elusive to direct observations in living cells; detection and characterization of myriads of such loops is a major challenge. The lack of a tractable physical model of a polymer folded into loops limits our ability to interpret experimental data and detect loops. Here, we introduce a new physical model - a polymer folded into a sequence of loops, and solve it analytically. Our model and a simple geometrical argument show how loops affect statistics of contacts in a polymer across different scales, explaining universally observed shapes of the contact probability. Moreover, we reveal that folding into loops reduces the density of topological entanglements, a novel phenomenon we refer as "the dilution of entanglements". Supported by simulations this finding suggests that up to ~ 1 - 2Mb chromosomes with loops are not topologically constrained, yet become crumpled at larger scales. Our theoretical framework allows inference of loop characteristics, draws a new picture of chromosome organization, and shows how folding into loops affects topological properties of crumpled polymers.
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Affiliation(s)
- Kirill E. Polovnikov
- Current address: Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Paris, France
- Institute of Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139
| | | | - Sergey Belan
- Landau Institute for Theoretical Physics, Russian Academy of Sciences, Chernogolovka, Russia
- National Research University Higher School of Economics, Faculty of Physics, Moscow, Russia
| | - Maxim Imakaev
- Institute of Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Hugo B. Brandão
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Leonid A. Mirny
- Institute of Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
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15
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Gil J, Rosin LF, Navarrete E, Chowdhury N, Abraham S, Cornilleau G, Lei EP, Mozziconacci J, Mirny LA, Muller H, Drinnenberg IA. Unique territorial and sub-chromosomal organization revealed in the holocentric moth Bombyx mori. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.14.557757. [PMID: 37745315 PMCID: PMC10515926 DOI: 10.1101/2023.09.14.557757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The hallmarks of chromosome organization in multicellular eukaryotes are chromosome territories (CT), chromatin compartments, and different types of domains, including topologically associated domains (TADs). Yet, most of these concepts derive from analyses of organisms with monocentric chromosomes. Here we describe the 3D genome architecture of an organism with holocentric chromosomes, the silkworm Bombyx mori . At the genome-wide scale, B. mori chromosomes form highly separated territories and lack substantial trans contacts. As described in other eukaryotes, B. mori chromosomes segregate into an active A and an inactive B compartment. Remarkably, we also identify a third compartment, Secluded "S", with a unique contact pattern. Compartment S shows strong enrichment of short-range contacts and depletion of long-range contacts. It hosts a unique combination of genetic and epigenetic features, localizes at the periphery of CTs and shows developmental plasticity. Biophysical modeling shows that formation of such secluded domains requires a new mechanism - a high density of extruded loops within them along with low level of extrusion and compartmentalization of A and B. Together with other evidence of loop extrusion in interphase, this suggests SMC-mediated loop extrusion in this insect. Overall, our analyses highlight the evolutionary plasticity of 3D genome organization driven by a new combination of known processes.
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16
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Batty P, Langer CCH, Takács Z, Tang W, Blaukopf C, Peters J, Gerlich DW. Cohesin-mediated DNA loop extrusion resolves sister chromatids in G2 phase. EMBO J 2023; 42:e113475. [PMID: 37357575 PMCID: PMC10425840 DOI: 10.15252/embj.2023113475] [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: 01/10/2023] [Revised: 05/26/2023] [Accepted: 06/14/2023] [Indexed: 06/27/2023] Open
Abstract
Genetic information is stored in linear DNA molecules, which are highly folded inside cells. DNA replication along the folded template path yields two sister chromatids that initially occupy the same nuclear region in an intertwined arrangement. Dividing cells must disentangle and condense the sister chromatids into separate bodies such that a microtubule-based spindle can move them to opposite poles. While the spindle-mediated transport of sister chromatids has been studied in detail, the chromosome-intrinsic mechanics presegregating sister chromatids have remained elusive. Here, we show that human sister chromatids resolve extensively already during interphase, in a process dependent on the loop-extruding activity of cohesin, but not that of condensins. Increasing cohesin's looping capability increases sister DNA resolution in interphase nuclei to an extent normally seen only during mitosis, despite the presence of abundant arm cohesion. That cohesin can resolve sister chromatids so extensively in the absence of mitosis-specific activities indicates that DNA loop extrusion is a generic mechanism for segregating replicated genomes, shared across different Structural Maintenance of Chromosomes (SMC) protein complexes in all kingdoms of life.
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Affiliation(s)
- Paul Batty
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
- Vienna BioCenter PhD ProgramDoctoral School of the University of Vienna and Medical University of ViennaViennaAustria
| | - Christoph CH Langer
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
| | - Zsuzsanna Takács
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
| | - Wen Tang
- Research Institute of Molecular Pathology (IMP)Vienna BioCenter (VBC)ViennaAustria
| | - Claudia Blaukopf
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
| | - Jan‐Michael Peters
- Research Institute of Molecular Pathology (IMP)Vienna BioCenter (VBC)ViennaAustria
| | - Daniel W Gerlich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
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17
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Eshghi I, Zidovska A, Grosberg AY. Model chromatin flows: numerical analysis of linear and nonlinear hydrodynamics inside a sphere. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:69. [PMID: 37540478 DOI: 10.1140/epje/s10189-023-00327-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/25/2023] [Indexed: 08/05/2023]
Abstract
We solve a hydrodynamic model of active chromatin dynamics, within a confined geometry simulating the cell nucleus. Using both analytical and numerical methods, we describe the behavior of the chromatin polymer driven by the activity of motors having polar symmetry, both in the linear response regime as well as in the long-term, fully nonlinear regime of the flows. The introduction of a boundary induces a particular geometry in the flows of chromatin, which we describe using vector spherical harmonics, a tool which greatly simplifies both our analytical and numerical approaches. We find that the long-term behavior of this model in confinement is dominated by steady, transverse flows of chromatin which circulate around the spherical domain. These circulating flows are found to be robust to perturbations, and their characteristic size is set by the size of the domain. This gives us further insight into active chromatin dynamics in the cell nucleus, and provides a foundation for development of further, more complex models of active chromatin dynamics.
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Affiliation(s)
- Iraj Eshghi
- Center for Soft Matter Research, Department of Physics, New York University, New York, NY, 10003, USA
| | - Alexandra Zidovska
- Center for Soft Matter Research, Department of Physics, New York University, New York, NY, 10003, USA
| | - Alexander Y Grosberg
- Center for Soft Matter Research, Department of Physics, New York University, New York, NY, 10003, USA.
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18
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Braceros AK, Schertzer MD, Omer A, Trotman JB, Davis ES, Dowen JM, Phanstiel DH, Aiden EL, Calabrese JM. Proximity-dependent recruitment of Polycomb repressive complexes by the lncRNA Airn. Cell Rep 2023; 42:112803. [PMID: 37436897 PMCID: PMC10441531 DOI: 10.1016/j.celrep.2023.112803] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 05/10/2023] [Accepted: 06/26/2023] [Indexed: 07/14/2023] Open
Abstract
During mouse embryogenesis, expression of the long non-coding RNA (lncRNA) Airn leads to gene repression and recruitment of Polycomb repressive complexes (PRCs) to varying extents over a 15-Mb domain. The mechanisms remain unclear. Using high-resolution approaches, we show in mouse trophoblast stem cells that Airn expression induces long-range changes to chromatin architecture that coincide with PRC-directed modifications and center around CpG island promoters that contact the Airn locus even in the absence of Airn expression. Intensity of contact between the Airn lncRNA and chromatin correlated with underlying intensity of PRC recruitment and PRC-directed modifications. Deletion of CpG islands that contact the Airn locus altered long-distance repression and PRC activity in a manner that correlated with changes in chromatin architecture. Our data imply that the extent to which Airn expression recruits PRCs to chromatin is controlled by DNA regulatory elements that modulate proximity of the Airn lncRNA product to its target DNA.
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Affiliation(s)
- Aki K Braceros
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; RNA Discovery Center, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Mechanistic, Interdisciplinary Studies of Biological Systems, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Megan D Schertzer
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Arina Omer
- Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jackson B Trotman
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; RNA Discovery Center, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Eric S Davis
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jill M Dowen
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Douglas H Phanstiel
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA; Thurston Arthritis Research Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Erez Lieberman Aiden
- Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - J Mauro Calabrese
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; RNA Discovery Center, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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19
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Schede HH, Natarajan P, Chakraborty AK, Shrinivas K. A model for organization and regulation of nuclear condensates by gene activity. Nat Commun 2023; 14:4152. [PMID: 37438363 DOI: 10.1038/s41467-023-39878-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 07/03/2023] [Indexed: 07/14/2023] Open
Abstract
Condensation by phase separation has recently emerged as a mechanism underlying many nuclear compartments essential for cellular functions. Nuclear condensates enrich nucleic acids and proteins, localize to specific genomic regions, and often promote gene expression. How diverse properties of nuclear condensates are shaped by gene organization and activity is poorly understood. Here, we develop a physics-based model to interrogate how spatially-varying transcription activity impacts condensate properties and dynamics. Our model predicts that spatial clustering of active genes can enable precise localization and de novo nucleation of condensates. Strong clustering and high activity results in aspherical condensate morphologies. Condensates can flow towards distant gene clusters and competition between multiple clusters lead to stretched morphologies and activity-dependent repositioning. Overall, our model predicts and recapitulates morphological and dynamical features of diverse nuclear condensates and offers a unified mechanistic framework to study the interplay between non-equilibrium processes, spatially-varying transcription, and multicomponent condensates in cell biology.
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Affiliation(s)
- Halima H Schede
- School of Life Sciences, École Polytechnique Fédérale Lausanne, CH-1015, Lausanne, Switzerland
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Pradeep Natarajan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Arup K Chakraborty
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Krishna Shrinivas
- NSF-Simons Center for Mathematical & Statistical Analysis of Biology, Harvard University, Cambridge, MA, USA.
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20
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Ramasamy S, Aljahani A, Karpinska MA, Cao TBN, Velychko T, Cruz JN, Lidschreiber M, Oudelaar AM. The Mediator complex regulates enhancer-promoter interactions. Nat Struct Mol Biol 2023:10.1038/s41594-023-01027-2. [PMID: 37430065 DOI: 10.1038/s41594-023-01027-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 05/30/2023] [Indexed: 07/12/2023]
Abstract
Enhancer-mediated gene activation generally requires physical proximity between enhancers and their target gene promoters. However, the molecular mechanisms by which interactions between enhancers and promoters are formed are not well understood. Here, we investigate the function of the Mediator complex in the regulation of enhancer-promoter interactions, by combining rapid protein depletion and high-resolution MNase-based chromosome conformation capture approaches. We show that depletion of Mediator leads to reduced enhancer-promoter interaction frequencies, which are associated with a strong decrease in gene expression. In addition, we find increased interactions between CTCF-binding sites upon Mediator depletion. These changes in chromatin architecture are associated with a redistribution of the Cohesin complex on chromatin and a reduction in Cohesin occupancy at enhancers. Together, our results indicate that the Mediator and Cohesin complexes contribute to enhancer-promoter interactions and provide insights into the molecular mechanisms by which communication between enhancers and promoters is regulated.
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Affiliation(s)
- Shyam Ramasamy
- Genome Organization and Regulation, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Abrar Aljahani
- Genome Organization and Regulation, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Magdalena A Karpinska
- Genome Organization and Regulation, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - T B Ngoc Cao
- Genome Organization and Regulation, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Taras Velychko
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - J Neos Cruz
- Genome Organization and Regulation, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Michael Lidschreiber
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - A Marieke Oudelaar
- Genome Organization and Regulation, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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21
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Botchkarev VA, Fessing MY, Sharov AA. Deciphering a Message from the Nucleus: How Transcription Factors and Spatial Chromatin Interactions Orchestrate Epidermal Differentiation. J Invest Dermatol 2023; 143:1117-1120. [PMID: 37045617 PMCID: PMC10715816 DOI: 10.1016/j.jid.2023.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 04/14/2023]
Affiliation(s)
- Vladimir A Botchkarev
- Department of Dermatology, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Michael Y Fessing
- Centre for Skin Sciences, School of Chemistry and Biosciences, University of Bradford, West Yorkshire, United Kingdom
| | - Andrey A Sharov
- Department of Dermatology, Boston University School of Medicine, Boston, Massachusetts, USA
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22
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Hafner A, Park M, Berger SE, Murphy SE, Nora EP, Boettiger AN. Loop stacking organizes genome folding from TADs to chromosomes. Mol Cell 2023; 83:1377-1392.e6. [PMID: 37146570 PMCID: PMC10167645 DOI: 10.1016/j.molcel.2023.04.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 02/17/2023] [Accepted: 04/06/2023] [Indexed: 05/07/2023]
Abstract
Although population-level analyses revealed significant roles for CTCF and cohesin in mammalian genome organization, their contributions at the single-cell level remain incompletely understood. Here, we used a super-resolution microscopy approach to measure the effects of removal of CTCF or cohesin in mouse embryonic stem cells. Single-chromosome traces revealed cohesin-dependent loops, frequently stacked at their loop anchors forming multi-way contacts (hubs), bridging across TAD boundaries. Despite these bridging interactions, chromatin in intervening TADs was not intermixed, remaining separated in distinct loops around the hub. At the multi-TAD scale, steric effects from loop stacking insulated local chromatin from ultra-long range (>4 Mb) contacts. Upon cohesin removal, the chromosomes were more disordered and increased cell-cell variability in gene expression. Our data revise the TAD-centric understanding of CTCF and cohesin and provide a multi-scale, structural picture of how they organize the genome on the single-cell level through distinct contributions to loop stacking.
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Affiliation(s)
- Antonina Hafner
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Minhee Park
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Scott E Berger
- Biophysics Program, Stanford University, Stanford, CA, USA
| | - Sedona E Murphy
- Department of Developmental Biology, Stanford University, Stanford, CA, USA; Department of Genetics, Stanford University, Stanford, CA, USA
| | - Elphège P Nora
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
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23
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Karpinska MA, Oudelaar AM. The role of loop extrusion in enhancer-mediated gene activation. Curr Opin Genet Dev 2023; 79:102022. [PMID: 36842325 DOI: 10.1016/j.gde.2023.102022] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/13/2023] [Accepted: 01/25/2023] [Indexed: 02/28/2023]
Abstract
Gene expression patterns in complex multicellular organisms are regulated by enhancers, which communicate with their target gene promoters in three-dimensional (3D) chromatin structures. Despite advances in our understanding of the mechanisms that organize mammalian genomes into compartments and topologically associating domains (TADs), it is not well understood how specific interactions between enhancers and promoters are controlled in this 3D context. In this review, we give an overview of recent evidence that shows that a process of loop extrusion plays an important role in the regulation of enhancer-promoter communication and discuss recent insights into the molecular mechanism by which loop extrusion contributes to enhancer-mediated gene activation.
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Affiliation(s)
- Magdalena A Karpinska
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany. https://twitter.com/@MagdalenaKarp
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24
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Chakraborty S, Kopitchinski N, Zuo Z, Eraso A, Awasthi P, Chari R, Mitra A, Tobias IC, Moorthy SD, Dale RK, Mitchell JA, Petros TJ, Rocha PP. Enhancer-promoter interactions can bypass CTCF-mediated boundaries and contribute to phenotypic robustness. Nat Genet 2023; 55:280-290. [PMID: 36717694 PMCID: PMC10758292 DOI: 10.1038/s41588-022-01295-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 12/20/2022] [Indexed: 01/31/2023]
Abstract
How enhancers activate their distal target promoters remains incompletely understood. Here we dissect how CTCF-mediated loops facilitate and restrict such regulatory interactions. Using an allelic series of mouse mutants, we show that CTCF is neither required for the interaction of the Sox2 gene with distal enhancers, nor for its expression. Insertion of various combinations of CTCF motifs, between Sox2 and its distal enhancers, generated boundaries with varying degrees of insulation that directly correlated with reduced transcriptional output. However, in both epiblast and neural tissues, enhancer contacts and transcriptional induction could not be fully abolished, and insertions failed to disrupt implantation and neurogenesis. In contrast, Sox2 expression was undetectable in the anterior foregut of mutants carrying the strongest boundaries, and these animals fully phenocopied loss of SOX2 in this tissue. We propose that enhancer clusters with a high density of regulatory activity can better overcome physical barriers to maintain faithful gene expression and phenotypic robustness.
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Affiliation(s)
- Shreeta Chakraborty
- Unit on Genome Structure and Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Nina Kopitchinski
- Unit on Genome Structure and Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Zhenyu Zuo
- Unit on Genome Structure and Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Ariel Eraso
- Unit on Genome Structure and Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Parirokh Awasthi
- Laboratory Animal Sciences Program, Frederick National Lab for Cancer Research, Frederick, MD, USA
| | - Raj Chari
- Laboratory Animal Sciences Program, Frederick National Lab for Cancer Research, Frederick, MD, USA
| | - Apratim Mitra
- Bioinformatics and Scientific Programming Core, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Ian C Tobias
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Sakthi D Moorthy
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Ryan K Dale
- Bioinformatics and Scientific Programming Core, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Jennifer A Mitchell
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Timothy J Petros
- Unit on Cellular and Molecular Neurodevelopment, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Pedro P Rocha
- Unit on Genome Structure and Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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25
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Abstract
In animals, the sequences for controlling gene expression do not concentrate just at the transcription start site of genes, but are frequently thousands to millions of base pairs distal to it. The interaction of these sequences with one another and their transcription start sites is regulated by factors that shape the three-dimensional (3D) organization of the genome within the nucleus. Over the past decade, indirect tools exploiting high-throughput DNA sequencing have helped to map this 3D organization, have identified multiple key regulators of its structure and, in the process, have substantially reshaped our view of how 3D genome architecture regulates transcription. Now, new tools for high-throughput super-resolution imaging of chromatin have directly visualized the 3D chromatin organization, settling some debates left unresolved by earlier indirect methods, challenging some earlier models of regulatory specificity and creating hypotheses about the role of chromatin structure in transcriptional regulation.
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26
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Gitchev T, Zala G, Meister P, Jost D. 3DPolyS-LE: an accessible simulation framework to model the interplay between chromatin and loop extrusion. Bioinformatics 2022; 38:5454-5456. [PMID: 36355469 PMCID: PMC9750120 DOI: 10.1093/bioinformatics/btac705] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 10/05/2022] [Indexed: 11/12/2022] Open
Abstract
SUMMARY Recent studies suggest that the loop extrusion activity of Structural Maintenance of Chromosomes complexes is central to proper organization of genomes in vivo. Polymer physics-based modeling of chromosome structure has been instrumental to assess which structures such extrusion can create. Only few laboratories however have the technical and computational expertise to create in silico models combining dynamic features of chromatin and loop extruders. Here, we present 3DPolyS-LE, a self-contained, easy to use modeling and simulation framework allowing non-specialists to ask how specific properties of loop extruders and boundary elements impact on 3D chromosome structure. 3DPolyS-LE also provides algorithms to compare predictions with experimental Hi-C data. AVAILABILITY AND IMPLEMENTATION Software available at https://gitlab.com/togop/3DPolyS-LE; implemented in Python and Fortran 2003 and supported on any Unix-based operating system (Linux and Mac OS). SUPPLEMENTARY INFORMATION Supplementary information are available at Bioinformatics online.
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Affiliation(s)
| | - Gabriel Zala
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern 3012, Switzerland
| | | | - Daniel Jost
- To whom correspondence should be addressed. or
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27
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Chi Y, Shi J, Xing D, Tan L. Every gene everywhere all at once: High-precision measurement of 3D chromosome architecture with single-cell Hi-C. Front Mol Biosci 2022; 9:959688. [PMID: 36275628 PMCID: PMC9583135 DOI: 10.3389/fmolb.2022.959688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 09/06/2022] [Indexed: 11/13/2022] Open
Abstract
The three-dimensional (3D) structure of chromosomes influences essential biological processes such as gene expression, genome replication, and DNA damage repair and has been implicated in many developmental and degenerative diseases. In the past two centuries, two complementary genres of technology-microscopy, such as fluorescence in situ hybridization (FISH), and biochemistry, such as chromosome conformation capture (3C or Hi-C)-have revealed general principles of chromosome folding in the cell nucleus. However, the extraordinary complexity and cell-to-cell variability of the chromosome structure necessitate new tools with genome-wide coverage and single-cell precision. In the past decade, single-cell Hi-C emerges as a new approach that builds upon yet conceptually differs from bulk Hi-C assays. Instead of measuring population-averaged statistical properties of chromosome folding, single-cell Hi-C works as a proximity-based "biochemical microscope" that measures actual 3D structures of individual genomes, revealing features hidden in bulk Hi-C such as radial organization, multi-way interactions, and chromosome intermingling. Single-cell Hi-C has been used to study highly dynamic processes such as the cell cycle, cell-type-specific chromosome architecture ("structure types"), and structure-expression interplay, deepening our understanding of DNA organization and function.
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Affiliation(s)
- Yi Chi
- Biomedical Pioneering Innovation Center, Peking University, Beijing, China,Innovation Center for Genomics, Peking University, Beijing, China
| | - Jenny Shi
- Department of Neurobiology, Stanford University, Stanford, CA, United States,Department of Chemistry, Stanford University, Stanford, CA, United States,Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Dong Xing
- Biomedical Pioneering Innovation Center, Peking University, Beijing, China,Innovation Center for Genomics, Peking University, Beijing, China,*Correspondence: Longzhi Tan, ; Dong Xing,
| | - Longzhi Tan
- Department of Neurobiology, Stanford University, Stanford, CA, United States,Department of Bioengineering, Stanford University, Stanford, CA, United States,*Correspondence: Longzhi Tan, ; Dong Xing,
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Abstract
Genomic DNA is organized three-dimensionally in the nucleus as chromatin. Recent accumulating evidence has demonstrated that chromatin organizes into numerous dynamic domains in higher eukaryotic cells, which act as functional units of the genome. These compacted domains facilitate DNA replication and gene regulation. Undamaged chromatin is critical for healthy cells to function and divide. However, the cellular genome is constantly threatened by many sources of DNA damage (e.g., radiation). How do cells maintain their genome integrity when subjected to DNA damage? This chapter describes how the compact state of chromatin safeguards the genome from radiation damage and chemical attacks. Together with recent genomics data, our finding suggests that DNA compaction, such as chromatin domain formation, plays a critical role in maintaining genome integrity. But does the formation of such domains limit DNA accessibility inside the domain and hinder the recruitment of repair machinery to the damaged site(s) during DNA repair? To approach this issue, we first describe a sensitive imaging method to detect changes in chromatin states in living cells (single-nucleosome imaging/tracking). We then use this method to explain how cells can overcome potential recruiting difficulties; cells can decompact chromatin domains following DNA damage and temporarily increase chromatin motion (∼DNA accessibility) to perform efficient DNA repair. We also speculate on how chromatin compaction affects DNA damage-resistance in the clinical setting.
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Affiliation(s)
- Katsuhiko Minami
- Genome Dynamics Laboratory, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Shizuoka, Japan; Department of Genetics, School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Shizuoka, Japan
| | - Shiori Iida
- Genome Dynamics Laboratory, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Shizuoka, Japan; Department of Genetics, School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Shizuoka, Japan
| | - Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Shizuoka, Japan; Department of Genetics, School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Shizuoka, Japan.
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29
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García Fernández F, Almayrac E, Carré Simon À, Batrin R, Khalil Y, Boissac M, Fabre E. Global chromatin mobility induced by a DSB is dictated by chromosomal conformation and defines the HR outcome. eLife 2022; 11:78015. [PMID: 36125964 PMCID: PMC9489209 DOI: 10.7554/elife.78015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 09/08/2022] [Indexed: 12/16/2022] Open
Abstract
Repair of DNA double-strand breaks (DSBs) is crucial for genome integrity. A conserved response to DSBs is an increase in chromatin mobility that can be local, at the site of the DSB, or global, at undamaged regions of the genome. Here, we address the function of global chromatin mobility during homologous recombination (HR) of a single, targeted, controlled DSB. We set up a system that tracks HR in vivo over time and show that two types of DSB-induced global chromatin mobility are involved in HR, depending on the position of the DSB. Close to the centromere, a DSB induces global mobility that depends solely on H2A(X) phosphorylation and accelerates repair kinetics, but is not essential. In contrast, the global mobility induced by a DSB away from the centromere becomes essential for HR repair and is triggered by homology search through a mechanism that depends on H2A(X) phosphorylation, checkpoint progression, and Rad51. Our data demonstrate that global mobility is governed by chromosomal conformation and differentially coordinates repair by HR.
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Affiliation(s)
| | - Etienne Almayrac
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Ànnia Carré Simon
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Renaud Batrin
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Yasmine Khalil
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Michel Boissac
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Emmanuelle Fabre
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
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30
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The role of chromatin loop extrusion in antibody diversification. Nat Rev Immunol 2022; 22:550-566. [PMID: 35169260 PMCID: PMC9376198 DOI: 10.1038/s41577-022-00679-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2022] [Indexed: 12/15/2022]
Abstract
Cohesin mediates chromatin loop formation across the genome by extruding chromatin between convergently oriented CTCF-binding elements. Recent studies indicate that cohesin-mediated loop extrusion in developing B cells presents immunoglobulin heavy chain (Igh) variable (V), diversity (D) and joining (J) gene segments to RAG endonuclease through a process referred to as RAG chromatin scanning. RAG initiates V(D)J recombinational joining of these gene segments to generate the large number of different Igh variable region exons that are required for immune responses to diverse pathogens. Antigen-activated mature B cells also use chromatin loop extrusion to mediate the synapsis, breakage and end joining of switch regions flanking Igh constant region exons during class-switch recombination, which allows for the expression of different antibody constant region isotypes that optimize the functions of antigen-specific antibodies to eliminate pathogens. Here, we review recent advances in our understanding of chromatin loop extrusion during V(D)J recombination and class-switch recombination at the Igh locus.
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31
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Bauer M, Payer B, Filion GJ. Causality in transcription and genome folding: Insights from X inactivation. Bioessays 2022; 44:e2200105. [PMID: 36028473 DOI: 10.1002/bies.202200105] [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: 06/01/2022] [Revised: 08/11/2022] [Accepted: 08/14/2022] [Indexed: 11/10/2022]
Abstract
The spatial organization of genomes is becoming increasingly understood. In mammals, where it is most investigated, this organization ties in with transcription, so an important research objective is to understand whether gene activity is a cause or a consequence of genome folding in space. In this regard, the phenomena of X-chromosome inactivation and reactivation open a unique window of investigation because of the singularities of the inactive X chromosome. Here we focus on the cause-consequence nexus between genome conformation and transcription and explain how recent results about the structural changes associated with inactivation and reactivation of the X chromosome shed light on this problem.
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Affiliation(s)
- Moritz Bauer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bernhard Payer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Guillaume J Filion
- Dept. Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
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32
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Deciphering the regulatory logic of a chromatin domain boundary. Nat Genet 2022; 54:914-915. [PMID: 35817980 DOI: 10.1038/s41588-022-01086-z] [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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33
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Quiroga IY, Ahn JH, Wang GG, Phanstiel D. Oncogenic fusion proteins and their role in three-dimensional chromatin structure, phase separation, and cancer. Curr Opin Genet Dev 2022; 74:101901. [PMID: 35427897 PMCID: PMC9156545 DOI: 10.1016/j.gde.2022.101901] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/17/2022] [Accepted: 03/05/2022] [Indexed: 11/27/2022]
Abstract
Three-dimensional (3D) chromatin structure plays a critical role in development, gene regulation, and cellular identity. Alterations to this structure can have profound effects on cellular phenotypes and have been associated with a variety of diseases including multiple types of cancer. One of several forces that help shape 3D chromatin structure is liquid-liquid phase separation, a form of self-association between biomolecules that can sequester regions of chromatin into subnuclear droplets or even membraneless organelles like nucleoli. This review focuses on a class of oncogenic fusion proteins that appear to exert their oncogenic function via phase-separation-driven alterations to 3D chromatin structure. Here, we review what is known about the mechanisms by which these oncogenic fusion proteins phase separate in the nucleus and their role in shaping the 3D chromatin structure. We discuss the potential for this phenomenon to be a more widespread mechanism of oncogenesis.
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Affiliation(s)
- Ivana Y Quiroga
- Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jeong Hyun Ahn
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Gang Greg Wang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
| | - Douglas Phanstiel
- Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
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34
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Team architecture in 3D genomic interactions revealed through nanopore sequencing. Nat Biotechnol 2022; 40:1437-1438. [PMID: 35650289 DOI: 10.1038/s41587-022-01290-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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35
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Deshpande AS, Ulahannan N, Pendleton M, Dai X, Ly L, Behr JM, Schwenk S, Liao W, Augello MA, Tyer C, Rughani P, Kudman S, Tian H, Otis HG, Adney E, Wilkes D, Mosquera JM, Barbieri CE, Melnick A, Stoddart D, Turner DJ, Juul S, Harrington E, Imieliński M. Identifying synergistic high-order 3D chromatin conformations from genome-scale nanopore concatemer sequencing. Nat Biotechnol 2022; 40:1488-1499. [DOI: 10.1038/s41587-022-01289-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 03/16/2022] [Indexed: 12/28/2022]
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36
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Aljahani A, Hua P, Karpinska MA, Quililan K, Davies JOJ, Oudelaar AM. Analysis of sub-kilobase chromatin topology reveals nano-scale regulatory interactions with variable dependence on cohesin and CTCF. Nat Commun 2022; 13:2139. [PMID: 35440598 PMCID: PMC9019034 DOI: 10.1038/s41467-022-29696-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 03/28/2022] [Indexed: 01/01/2023] Open
Abstract
Enhancers and promoters predominantly interact within large-scale topologically associating domains (TADs), which are formed by loop extrusion mediated by cohesin and CTCF. However, it is unclear whether complex chromatin structures exist at sub-kilobase-scale and to what extent fine-scale regulatory interactions depend on loop extrusion. To address these questions, we present an MNase-based chromosome conformation capture (3C) approach, which has enabled us to generate the most detailed local interaction data to date (20 bp resolution) and precisely investigate the effects of cohesin and CTCF depletion on chromatin architecture. Our data reveal that cis-regulatory elements have distinct internal nano-scale structures, within which local insulation is dependent on CTCF, but which are independent of cohesin. In contrast, we find that depletion of cohesin causes a subtle reduction in longer-range enhancer-promoter interactions and that CTCF depletion can cause rewiring of regulatory contacts. Together, our data show that loop extrusion is not essential for enhancer-promoter interactions, but contributes to their robustness and specificity and to precise regulation of gene expression.
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Affiliation(s)
- Abrar Aljahani
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Peng Hua
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | | | - Kimberly Quililan
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - James O J Davies
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.
| | - A Marieke Oudelaar
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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37
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BET proteins loop and compartmentalize the 3D genome. Nat Genet 2022; 54:370-371. [DOI: 10.1038/s41588-022-01031-0] [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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38
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Abstract
In eukaryotic cells, protein and RNA factors involved in genome activities like transcription, RNA processing, DNA replication, and repair accumulate in self-organizing membraneless chromatin subcompartments. These structures contribute to efficiently conduct chromatin-mediated reactions and to establish specific cellular programs. However, the underlying mechanisms for their formation are only partly understood. Recent studies invoke liquid-liquid phase separation (LLPS) of proteins and RNAs in the establishment of chromatin activity patterns. At the same time, the folding of chromatin in the nucleus can drive genome partitioning into spatially distinct domains. Here, the interplay between chromatin organization, chromatin binding, and LLPS is discussed by comparing and contrasting three prototypical chromatin subcompartments: the nucleolus, clusters of active RNA polymerase II, and pericentric heterochromatin domains. It is discussed how the different ways of chromatin compartmentalization are linked to transcription regulation, the targeting of soluble factors to certain parts of the genome, and to disease-causing genetic aberrations.
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Affiliation(s)
- Karsten Rippe
- Division of Chromatin Networks, German Cancer Research Center (DKFZ) and Bioquant, 69120 Heidelberg, Germany
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39
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Transcriptional Regulation and Implications for Controlling Hox Gene Expression. J Dev Biol 2022; 10:jdb10010004. [PMID: 35076545 PMCID: PMC8788451 DOI: 10.3390/jdb10010004] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 02/06/2023] Open
Abstract
Hox genes play key roles in axial patterning and regulating the regional identity of cells and tissues in a wide variety of animals from invertebrates to vertebrates. Nested domains of Hox expression generate a combinatorial code that provides a molecular framework for specifying the properties of tissues along the A–P axis. Hence, it is important to understand the regulatory mechanisms that coordinately control the precise patterns of the transcription of clustered Hox genes required for their roles in development. New insights are emerging about the dynamics and molecular mechanisms governing transcriptional regulation, and there is interest in understanding how these may play a role in contributing to the regulation of the expression of the clustered Hox genes. In this review, we summarize some of the recent findings, ideas and emerging mechanisms underlying the regulation of transcription in general and consider how they may be relevant to understanding the transcriptional regulation of Hox genes.
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40
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3D Genome Organization: Causes and Consequences for DNA Damage and Repair. Genes (Basel) 2021; 13:genes13010007. [PMID: 35052348 PMCID: PMC8775012 DOI: 10.3390/genes13010007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 01/02/2023] Open
Abstract
The inability to repair damaged DNA severely compromises the integrity of any organism. In eukaryotes, the DNA damage response (DDR) operates within chromatin, a tightly organized DNA–histone complex in a non-random manner within the nucleus. Chromatin thus orchestrates various cellular processes, including repair. Here, we examine the chromatin landscape before, during, and after the DNA damage, focusing on double strand breaks (DSBs). We study how chromatin is modified during the repair process, not only around the damaged region (in cis), but also genome-wide (in trans). Recent evidence has highlighted a complex landscape in which different chromatin parameters (stiffness, compaction, loops) are transiently modified, defining “codes” for each specific stage of the DDR. We illustrate a novel aspect of DDR where chromatin modifications contribute to the movement of DSB-damaged chromatin, as well as undamaged chromatin, ensuring the mobilization of DSBs, their clustering, and their repair processes.
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41
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Abstract
Genomic information is encoded on long strands of DNA, which are folded into chromatin and stored in a tiny nucleus. Nuclear chromatin is a negatively charged polymer composed of DNA, histones, and various nonhistone proteins. Because of its highly charged nature, chromatin structure varies greatly depending on the surrounding environment (e.g., cations, molecular crowding, etc.). New technologies to capture chromatin in living cells have been developed over the past 10 years. Our view on chromatin organization has drastically shifted from a regular and static one to a more variable and dynamic one. Chromatin forms numerous compact dynamic domains that act as functional units of the genome in higher eukaryotic cells and locally appear liquid-like. By changing DNA accessibility, these domains can govern various functions. Based on new evidences from versatile genomics and advanced imaging studies, we discuss the physical nature of chromatin in the crowded nuclear environment and how it is regulated.
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Affiliation(s)
- Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Shiori Iida
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Sachiko Tamura
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
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