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McDonald A, Murre C, Sedat J. Helical Coiled Nucleosome Chromosome Architectures during Cell Cycle Progression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.25.595892. [PMID: 38826250 PMCID: PMC11142257 DOI: 10.1101/2024.05.25.595892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Recent studies showed an interphase chromosome architecture, --- a specific coiled nucleosome structure, --- derived from cryo-preserved EM tomograms, and dispersed throughout the nucleus. The images were computationally processed to fill in the missing wedges of data caused by incomplete tomographic tilts. The resulting structures increased z-resolution enabling an extension of the proposed architecture to that of mitotic chromosomes. Here we provide additional insights and details into the coiled nucleosome chromosome architectures. We build on the defined chromosomes time-dependent structures in an effort to probe their dynamics. Variants of the coiled chromosome structures, possibly further defining specific regions, are discussed. We propose, based on generalized specific uncoiling of mitotic chromosomes in telophase, large-scale re-organization of interphase chromosomes. Chromosome territories, organized as micron-sized small patches, are constructed, satisfying complex volume considerations. Finally, we unveiled the structures of replicated coiled chromosomes, still attached to centromeres, as part of chromosome architecture. Significance Statement This study places all 46 sequenced human chromosomes, --- correctly filled with nucleosomes and in micron sized chromosome territories - into 10micron (average sized) nuclei. The chromosome architecture used a helical nucleosome coiled structure discerned from cryo-EM tomography, as was recently published ( https://doi.org/10.1073/pnas.2119101119 ). This chromosome architecture was further modeled to dynamic structures, structure variations and chromosome replication centromere complications. Finally, this chromosome architecture was modified to allow seamless transition through the cell cycle.
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2
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Shin S, Shi G, Cho HW, Thirumalai D. Transcription-induced active forces suppress chromatin motion. Proc Natl Acad Sci U S A 2024; 121:e2307309121. [PMID: 38489381 PMCID: PMC10963020 DOI: 10.1073/pnas.2307309121] [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: 05/02/2023] [Accepted: 02/06/2024] [Indexed: 03/17/2024] Open
Abstract
The organization of interphase chromosomes in a number of species is starting to emerge thanks to advances in a variety of experimental techniques. However, much less is known about the dynamics, especially in the functional states of chromatin. Some experiments have shown that the motility of individual loci in human interphase chromosome decreases during transcription and increases upon inhibiting transcription. This is a counterintuitive finding because it is thought that the active mechanical force (F) on the order of ten piconewtons, generated by RNA polymerase II (RNAPII) that is presumably transmitted to the gene-rich region of the chromatin, would render it more open, thus enhancing the mobility. We developed a minimal active copolymer model for interphase chromosomes to investigate how F affects the dynamical properties of chromatin. The movements of the loci in the gene-rich region are suppressed in an intermediate range of F and are enhanced at small F values, which has also been observed in experiments. In the intermediate F, the bond length between consecutive loci increases, becoming commensurate with the distance at the minimum of the attractive interaction between nonbonded loci. This results in a transient disorder-to-order transition, leading to a decreased mobility during transcription. Strikingly, the F-dependent change in the locus dynamics preserves the organization of the chromosome at [Formula: see text]. Transient ordering of the loci, which is not found in the polymers with random epigenetic profiles, in the gene-rich region might be a plausible mechanism for nucleating a dynamic network involving transcription factors, RNAPII, and chromatin.
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Affiliation(s)
- Sucheol Shin
- Department of Chemistry, The University of Texas at Austin, Austin, TX78712
| | - Guang Shi
- Department of Chemistry, The University of Texas at Austin, Austin, TX78712
- Department of Materials Science, University of Illinois, Urbana, IL61801
| | - Hyun Woo Cho
- Department of Fine Chemistry and Center for Functional Biomaterials, Seoul National University of Science and Technology, Seoul01811, Republic of Korea
| | - D. Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, TX78712
- Department of Physics, The University of Texas at Austin, Austin, TX78712
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3
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Bialek W, Shaevitz JW. Long Timescales, Individual Differences, and Scale Invariance in Animal Behavior. PHYSICAL REVIEW LETTERS 2024; 132:048401. [PMID: 38335334 DOI: 10.1103/physrevlett.132.048401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 11/27/2023] [Indexed: 02/12/2024]
Abstract
The explosion of data on animal behavior in more natural contexts highlights the fact that these behaviors exhibit correlations across many timescales. However, there are major challenges in analyzing these data: records of behavior in single animals have fewer independent samples than one might expect. In pooling data from multiple animals, individual differences can mimic long-ranged temporal correlations; conversely, long-ranged correlations can lead to an overestimate of individual differences. We suggest an analysis scheme that addresses these problems directly, apply this approach to data on the spontaneous behavior of walking flies, and find evidence for scale-invariant correlations over nearly three decades in time, from seconds to one hour. Three different measures of correlation are consistent with a single underlying scaling field of dimension Δ=0.180±0.005.
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Affiliation(s)
- William Bialek
- Joseph Henry Laboratories of Physics and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
- Center for Studies in Physics and Biology, Rockefeller University, New York, New York 10065, USA
| | - Joshua W Shaevitz
- Joseph Henry Laboratories of Physics and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
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4
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Papale A, Holcman D. Chromatin phase separated nanoregions explored by polymer cross-linker models and reconstructed from single particle trajectories. PLoS Comput Biol 2024; 20:e1011794. [PMID: 38266036 PMCID: PMC10843633 DOI: 10.1371/journal.pcbi.1011794] [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: 03/25/2023] [Revised: 02/05/2024] [Accepted: 01/01/2024] [Indexed: 01/26/2024] Open
Abstract
Phase separated domains (PSDs) are ubiquitous in cell biology, representing nanoregions of high molecular concentration. PSDs appear at diverse cellular domains, such as neuronal synapses but also in eukaryotic cell nucleus, limiting the access of transcription factors and thus preventing gene expression. We develop a generalized cross-linker polymer model, to study PSDs: we show that increasing the number of cross-linkers induces a polymer condensation, preventing access of diffusing molecules. To investigate how the PSDs restrict the motion of diffusing molecules, we compute the mean residence and first escaping times. Finally, we develop a method based on mean-square-displacement of single particle trajectories to reconstruct the properties of PSDs from the continuum range of anomalous exponents. We also show here that PSD generated by polymers do not induces a long-range attracting field (potential well), in contrast with nanodomains at neuronal synapses. To conclude, PSDs can result from condensed chromatin organization, where the number of cross-linkers controls molecular access.
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Affiliation(s)
- Andrea Papale
- Group of Computational Biology and Applied Mathemathics, Ecole Normale Supérieure, IBENS, Université PSL, Paris, France
| | - David Holcman
- Group of Computational Biology and Applied Mathemathics, Ecole Normale Supérieure, IBENS, Université PSL, Paris, France
- Churchill College, University of Cambridge, United Kingdom
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5
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Mielczarek O, Rogers CH, Zhan Y, Matheson LS, Stubbington MJT, Schoenfelder S, Bolland DJ, Javierre BM, Wingett SW, Várnai C, Segonds-Pichon A, Conn SJ, Krueger F, Andrews S, Fraser P, Giorgetti L, Corcoran AE. Intra- and interchromosomal contact mapping reveals the Igh locus has extensive conformational heterogeneity and interacts with B-lineage genes. Cell Rep 2023; 42:113074. [PMID: 37676766 PMCID: PMC10548092 DOI: 10.1016/j.celrep.2023.113074] [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: 02/27/2023] [Revised: 06/28/2023] [Accepted: 08/18/2023] [Indexed: 09/09/2023] Open
Abstract
To produce a diverse antibody repertoire, immunoglobulin heavy-chain (Igh) loci undergo large-scale alterations in structure to facilitate juxtaposition and recombination of spatially separated variable (VH), diversity (DH), and joining (JH) genes. These chromosomal alterations are poorly understood. Uncovering their patterns shows how chromosome dynamics underpins antibody diversity. Using tiled Capture Hi-C, we produce a comprehensive map of chromatin interactions throughout the 2.8-Mb Igh locus in progenitor B cells. We find that the Igh locus folds into semi-rigid subdomains and undergoes flexible looping of the VH genes to its 3' end, reconciling two views of locus organization. Deconvolution of single Igh locus conformations using polymer simulations identifies thousands of different structures. This heterogeneity may underpin the diversity of V(D)J recombination events. All three immunoglobulin loci also participate in a highly specific, developmentally regulated network of interchromosomal interactions with genes encoding B cell-lineage factors. This suggests a model of interchromosomal coordination of B cell development.
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Affiliation(s)
- Olga Mielczarek
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Carolyn H Rogers
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Yinxiu Zhan
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Louise S Matheson
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Michael J T Stubbington
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Stefan Schoenfelder
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Daniel J Bolland
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Biola M Javierre
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Steven W Wingett
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Csilla Várnai
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Anne Segonds-Pichon
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Simon J Conn
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Felix Krueger
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Simon Andrews
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Peter Fraser
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Anne E Corcoran
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
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6
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Melters DP, Neuman KC, Bentahar RS, Rakshit T, Dalal Y. Single molecule analysis of CENP-A chromatin by high-speed atomic force microscopy. eLife 2023; 12:e86709. [PMID: 37728600 PMCID: PMC10511241 DOI: 10.7554/elife.86709] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 09/01/2023] [Indexed: 09/21/2023] Open
Abstract
Chromatin accessibility is modulated in a variety of ways to create open and closed chromatin states, both of which are critical for eukaryotic gene regulation. At the single molecule level, how accessibility is regulated of the chromatin fiber composed of canonical or variant nucleosomes is a fundamental question in the field. Here, we developed a single-molecule tracking method where we could analyze thousands of canonical H3 and centromeric variant nucleosomes imaged by high-speed atomic force microscopy. This approach allowed us to investigate how changes in nucleosome dynamics in vitro inform us about transcriptional potential in vivo. By high-speed atomic force microscopy, we tracked chromatin dynamics in real time and determined the mean square displacement and diffusion constant for the variant centromeric CENP-A nucleosome. Furthermore, we found that an essential kinetochore protein CENP-C reduces the diffusion constant and mobility of centromeric nucleosomes along the chromatin fiber. We subsequently interrogated how CENP-C modulates CENP-A chromatin dynamics in vivo. Overexpressing CENP-C resulted in reduced centromeric transcription and impaired loading of new CENP-A molecules. From these data, we speculate that factors altering nucleosome mobility in vitro, also correspondingly alter transcription in vivo. Subsequently, we propose a model in which variant nucleosomes encode their own diffusion kinetics and mobility, and where binding partners can suppress or enhance nucleosome mobility.
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Affiliation(s)
- Daniël P Melters
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
| | - Keir C Neuman
- National Heart, Lung, and Blood Institute, Laboratory of Single Molecule BiophysicsBethesdaUnited States
| | - Reda S Bentahar
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
| | - Tatini Rakshit
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
- Department of Chemistry, Shiv Nadar UniversityDadriIndia
| | - Yamini Dalal
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
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7
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Brückner DB, Chen H, Barinov L, Zoller B, Gregor T. Stochastic motion and transcriptional dynamics of pairs of distal DNA loci on a compacted chromosome. Science 2023; 380:1357-1362. [PMID: 37384691 PMCID: PMC10439308 DOI: 10.1126/science.adf5568] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 05/31/2023] [Indexed: 07/01/2023]
Abstract
Chromosomes in the eukaryotic nucleus are highly compacted. However, for many functional processes, including transcription initiation, the pairwise motion of distal chromosomal elements such as enhancers and promoters is essential and necessitates dynamic fluidity. Here, we used a live-imaging assay to simultaneously measure the positions of pairs of enhancers and promoters and their transcriptional output while systematically varying the genomic separation between these two DNA loci. Our analysis reveals the coexistence of a compact globular organization and fast subdiffusive dynamics. These combined features cause an anomalous scaling of polymer relaxation times with genomic separation leading to long-ranged correlations. Thus, encounter times of DNA loci are much less dependent on genomic distance than predicted by existing polymer models, with potential consequences for eukaryotic gene expression.
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Affiliation(s)
- David B. Brückner
- Institute of Science and Technology, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Hongtao Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Lev Barinov
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Benjamin Zoller
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA
- Department of Developmental and Stem Cell Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, Paris, France
| | - Thomas Gregor
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA
- Department of Developmental and Stem Cell Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, Paris, France
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8
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Liang Z, Zhao L, Ye AY, Lin SG, Zhang Y, Guo C, Dai HQ, Ba Z, Alt FW. Contribution of the IGCR1 regulatory element and the 3' Igh CTCF-binding elements to regulation of Igh V(D)J recombination. Proc Natl Acad Sci U S A 2023; 120:e2306564120. [PMID: 37339228 PMCID: PMC10293834 DOI: 10.1073/pnas.2306564120] [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: 04/21/2023] [Accepted: 05/12/2023] [Indexed: 06/22/2023] Open
Abstract
Immunoglobulin heavy chain variable region exons are assembled in progenitor-B cells, from VH, D, and JH gene segments located in separate clusters across the Igh locus. RAG endonuclease initiates V(D)J recombination from a JH-based recombination center (RC). Cohesin-mediated extrusion of upstream chromatin past RC-bound RAG presents Ds for joining to JHs to form a DJH-RC. Igh has a provocative number and organization of CTCF-binding elements (CBEs) that can impede loop extrusion. Thus, Igh has two divergently oriented CBEs (CBE1 and CBE2) in the IGCR1 element between the VH and D/JH domains, over 100 CBEs across the VH domain convergent to CBE1, and 10 clustered 3'Igh-CBEs convergent to CBE2 and VH CBEs. IGCR1 CBEs segregate D/JH and VH domains by impeding loop extrusion-mediated RAG-scanning. Downregulation of WAPL, a cohesin unloader, in progenitor-B cells neutralizes CBEs, allowing DJH-RC-bound RAG to scan the VH domain and perform VH-to-DJH rearrangements. To elucidate potential roles of IGCR1-based CBEs and 3'Igh-CBEs in regulating RAG-scanning and elucidate the mechanism of the ordered transition from D-to-JH to VH-to-DJH recombination, we tested effects of inverting and/or deleting IGCR1 or 3'Igh-CBEs in mice and/or progenitor-B cell lines. These studies revealed that normal IGCR1 CBE orientation augments RAG-scanning impediment activity and suggest that 3'Igh-CBEs reinforce ability of the RC to function as a dynamic loop extrusion impediment to promote optimal RAG scanning activity. Finally, our findings indicate that ordered V(D)J recombination can be explained by a gradual WAPL downregulation mechanism in progenitor-B cells as opposed to a strict developmental switch.
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Affiliation(s)
- Zhuoyi Liang
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Lijuan Zhao
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Adam Yongxin Ye
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Sherry G. Lin
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Yiwen Zhang
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Chunguang Guo
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Hai-Qiang Dai
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Zhaoqing Ba
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
| | - Frederick W. Alt
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA02115
- Department of Genetics, Harvard Medical School, Boston, MA02115
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9
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van Staalduinen J, van Staveren T, Grosveld F, Wendt KS. Live-cell imaging of chromatin contacts opens a new window into chromatin dynamics. Epigenetics Chromatin 2023; 16:27. [PMID: 37349773 PMCID: PMC10288748 DOI: 10.1186/s13072-023-00503-9] [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: 04/13/2023] [Accepted: 06/15/2023] [Indexed: 06/24/2023] Open
Abstract
Our understanding of the organization of the chromatin fiber within the cell nucleus has made great progress in the last few years. High-resolution techniques based on next-generation sequencing as well as optical imaging that can investigate chromatin conformations down to the single cell level have revealed that chromatin structure is highly heterogeneous at the level of the individual allele. While TAD boundaries and enhancer-promoter pairs emerge as hotspots of 3D proximity, the spatiotemporal dynamics of these different types of chromatin contacts remain largely unexplored. Investigation of chromatin contacts in live single cells is necessary to close this knowledge gap and further enhance the current models of 3D genome organization and enhancer-promoter communication. In this review, we first discuss the potential of single locus labeling to study architectural and enhancer-promoter contacts and provide an overview of the available single locus labeling techniques such as FROS, TALE, CRISPR-dCas9 and ANCHOR, and discuss the latest developments and applications of these systems.
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Affiliation(s)
- Jente van Staalduinen
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Thomas van Staveren
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Frank Grosveld
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Kerstin S Wendt
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands.
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10
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Qiu Y, Feng D, Jiang W, Zhang T, Lu Q, Zhao M. 3D genome organization and epigenetic regulation in autoimmune diseases. Front Immunol 2023; 14:1196123. [PMID: 37346038 PMCID: PMC10279977 DOI: 10.3389/fimmu.2023.1196123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/17/2023] [Indexed: 06/23/2023] Open
Abstract
Three-dimensional (3D) genomics is an emerging field of research that investigates the relationship between gene regulatory function and the spatial structure of chromatin. Chromatin folding can be studied using chromosome conformation capture (3C) technology and 3C-based derivative sequencing technologies, including chromosome conformation capture-on-chip (4C), chromosome conformation capture carbon copy (5C), and high-throughput chromosome conformation capture (Hi-C), which allow scientists to capture 3D conformations from a single site to the entire genome. A comprehensive analysis of the relationships between various regulatory components and gene function also requires the integration of multi-omics data such as genomics, transcriptomics, and epigenomics. 3D genome folding is involved in immune cell differentiation, activation, and dysfunction and participates in a wide range of diseases, including autoimmune diseases. We describe hierarchical 3D chromatin organization in this review and conclude with characteristics of C-techniques and multi-omics applications of the 3D genome. In addition, we describe the relationship between 3D genome structure and the differentiation and maturation of immune cells and address how changes in chromosome folding contribute to autoimmune diseases.
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Affiliation(s)
- Yueqi Qiu
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, China
- Key Laboratory of Basic and Translational Research on Immune-Mediated Skin Diseases, Institute of Dermatology, Chinese Academy of Medical Sciences, Nanjing, China
| | - Delong Feng
- Department of Dermatology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Wenjuan Jiang
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, China
- Key Laboratory of Basic and Translational Research on Immune-Mediated Skin Diseases, Institute of Dermatology, Chinese Academy of Medical Sciences, Nanjing, China
| | - Tingting Zhang
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, China
- Key Laboratory of Basic and Translational Research on Immune-Mediated Skin Diseases, Institute of Dermatology, Chinese Academy of Medical Sciences, Nanjing, China
- State Key Laboratory of Natural Medicines, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Qianjin Lu
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, China
- Key Laboratory of Basic and Translational Research on Immune-Mediated Skin Diseases, Institute of Dermatology, Chinese Academy of Medical Sciences, Nanjing, China
- Department of Dermatology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Ming Zhao
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, China
- Key Laboratory of Basic and Translational Research on Immune-Mediated Skin Diseases, Institute of Dermatology, Chinese Academy of Medical Sciences, Nanjing, China
- Department of Dermatology, The Second Xiangya Hospital of Central South University, Changsha, China
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11
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Lu S, Hou Y, Zhang XE, Gao Y. Live cell imaging of DNA and RNA with fluorescent signal amplification and background reduction techniques. Front Cell Dev Biol 2023; 11:1216232. [PMID: 37342234 PMCID: PMC10277805 DOI: 10.3389/fcell.2023.1216232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 05/24/2023] [Indexed: 06/22/2023] Open
Abstract
Illuminating DNA and RNA dynamics in live cell can elucidate their life cycle and related biochemical activities. Various protocols have been developed for labeling the regions of interest in DNA and RNA molecules with different types of fluorescent probes. For example, CRISPR-based techniques have been extensively used for imaging genomic loci. However, some DNA and RNA molecules can still be difficult to tag and observe dynamically, such as genomic loci in non-repetitive regions. In this review, we will discuss the toolbox of techniques and methodologies that have been developed for imaging DNA and RNA. We will also introduce optimized systems that provide enhanced signal intensity or low background fluorescence for those difficult-to-tag molecules. These strategies can provide new insights for researchers when designing and using techniques to visualize DNA or RNA molecules.
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Affiliation(s)
- Song Lu
- Center for Advanced Measurement Science, National Institute of Metrology, Beijing, China
| | - Yu Hou
- Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Xian-En Zhang
- Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yunhua Gao
- Center for Advanced Measurement Science, National Institute of Metrology, Beijing, China
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12
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Liang Z, Zhao L, Yongxin Ye A, Lin SG, Zhang Y, Guo C, Dai HQ, Ba Z, Alt FW. Contribution of the IGCR1 regulatory element and the 3 'Igh CBEs to Regulation of Igh V(D)J Recombination. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.21.537836. [PMID: 37163018 PMCID: PMC10168220 DOI: 10.1101/2023.04.21.537836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Immunoglobulin heavy chain variable region exons are assembled in progenitor-B cells, from V H , D, and J H gene segments located in separate clusters across the Igh locus. RAG endonuclease initiates V(D)J recombination from a J H -based recombination center (RC). Cohesin-mediated extrusion of upstream chromatin past RC-bound RAG presents Ds for joining to J H s to form a DJ H -RC. Igh has a provocative number and organization of CTCF-binding-elements (CBEs) that can impede loop extrusion. Thus, Igh has two divergently oriented CBEs (CBE1 and CBE2) in the IGCR1 element between the V H and D/J H domains, over 100 CBEs across the V H domain convergent to CBE1, and 10 clustered 3' Igh -CBEs convergent to CBE2 and V H CBEs. IGCR1 CBEs segregate D/J H and V H domains by impeding loop extrusion-mediated RAG-scanning. Down-regulation of WAPL, a cohesin unloader, in progenitor-B cells neutralizes CBEs, allowing DJ H -RC-bound RAG to scan the VH domain and perform VH-to-DJH rearrangements. To elucidate potential roles of IGCR1-based CBEs and 3' Igh -CBEs in regulating RAG-scanning and elucidate the mechanism of the "ordered" transition from D-to-J H to V H -to-DJ H recombination, we tested effects of deleting or inverting IGCR1 or 3' Igh -CBEs in mice and/or progenitor-B cell lines. These studies revealed that normal IGCR1 CBE orientation augments RAG-scanning impediment activity and suggest that 3' Igh -CBEs reinforce ability of the RC to function as a dynamic loop extrusion impediment to promote optimal RAG scanning activity. Finally, our findings indicate that ordered V(D)J recombination can be explained by a gradual WAPL down-regulation mechanism in progenitor B cells as opposed to a strict developmental switch. SIGNIFICANCE STATEMENT To counteract diverse pathogens, vertebrates evolved adaptive immunity to generate diverse antibody repertoires through a B lymphocyte-specific somatic gene rearrangement process termed V(D)J recombination. Tight regulation of the V(D)J recombination process is vital to generating antibody diversity and preventing off-target activities that can predispose the oncogenic translocations. Recent studies have demonstrated V(D)J rearrangement is driven by cohesin-mediated chromatin loop extrusion, a process that establishes genomic loop domains by extruding chromatin, predominantly, between convergently-oriented CTCF looping factor-binding elements (CBEs). By deleting and inverting CBEs within a critical antibody heavy chain gene locus developmental control region and a loop extrusion chromatin-anchor at the downstream end of this locus, we reveal how these elements developmentally contribute to generation of diverse antibody repertoires.
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13
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Yang JH, Brandão HB, Hansen AS. DNA double-strand break end synapsis by DNA loop extrusion. Nat Commun 2023; 14:1913. [PMID: 37024496 PMCID: PMC10079674 DOI: 10.1038/s41467-023-37583-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 03/23/2023] [Indexed: 04/08/2023] Open
Abstract
DNA double-strand breaks (DSBs) occur every cell cycle and must be efficiently repaired. Non-homologous end joining (NHEJ) is the dominant pathway for DSB repair in G1-phase. The first step of NHEJ is to bring the two DSB ends back into proximity (synapsis). Although synapsis is generally assumed to occur through passive diffusion, we show that passive diffusion is unlikely to produce the synapsis speed observed in cells. Instead, we hypothesize that DNA loop extrusion facilitates synapsis. By combining experimentally constrained simulations and theory, we show that a simple loop extrusion model constrained by previous live-cell imaging data only modestly accelerates synapsis. Instead, an expanded loop extrusion model with targeted loading of loop extruding factors (LEFs), a small portion of long-lived LEFs, and LEF stabilization by boundary elements and DSB ends achieves fast synapsis with near 100% efficiency. We propose that loop extrusion contributes to DSB repair by mediating fast synapsis.
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Affiliation(s)
- Jin H Yang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
- Koch Institute for Integrative Cancer Research, Cambridge, MA, 02142, USA
| | - Hugo B Brandão
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
- Koch Institute for Integrative Cancer Research, Cambridge, MA, 02142, USA.
- Illumina Inc., San Diego, CA, 92122, USA.
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
- Koch Institute for Integrative Cancer Research, Cambridge, MA, 02142, USA.
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14
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An Igh distal enhancer modulates antigen receptor diversity by determining locus conformation. Nat Commun 2023; 14:1225. [PMID: 36869028 PMCID: PMC9984487 DOI: 10.1038/s41467-023-36414-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 01/31/2023] [Indexed: 03/05/2023] Open
Abstract
The mouse Igh locus is organized into a developmentally regulated topologically associated domain (TAD) that is divided into subTADs. Here we identify a series of distal VH enhancers (EVHs) that collaborate to configure the locus. EVHs engage in a network of long-range interactions that interconnect the subTADs and the recombination center at the DHJH gene cluster. Deletion of EVH1 reduces V gene rearrangement in its vicinity and alters discrete chromatin loops and higher order locus conformation. Reduction in the rearrangement of the VH11 gene used in anti-PtC responses is a likely cause of the observed reduced splenic B1 B cell compartment. EVH1 appears to block long-range loop extrusion that in turn contributes to locus contraction and determines the proximity of distant VH genes to the recombination center. EVH1 is a critical architectural and regulatory element that coordinates chromatin conformational states that favor V(D)J rearrangement.
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15
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Pecori F, Torres-Padilla ME. Dynamics of nuclear architecture during early embryonic development and lessons from liveimaging. Dev Cell 2023; 58:435-449. [PMID: 36977375 PMCID: PMC10062924 DOI: 10.1016/j.devcel.2023.02.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 11/29/2022] [Accepted: 02/27/2023] [Indexed: 03/29/2023]
Abstract
Nuclear organization has emerged as a potential key regulator of genome function. During development, the deployment of transcriptional programs must be tightly coordinated with cell division and is often accompanied by major changes in the repertoire of expressed genes. These transcriptional and developmental events are paralleled by changes in the chromatin landscape. Numerous studies have revealed the dynamics of nuclear organization underlying them. In addition, advances in live-imaging-based methodologies enable the study of nuclear organization with high spatial and temporal resolution. In this Review, we summarize the current knowledge of the changes in nuclear architecture in the early embryogenesis of various model systems. Furthermore, to highlight the importance of integrating fixed-cell and live approaches, we discuss how different live-imaging techniques can be applied to examine nuclear processes and their contribution to our understanding of transcription and chromatin dynamics in early development. Finally, we provide future avenues for outstanding questions in this field.
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16
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Chung YC, Bisht M, Thuma J, Tu LC. Single-chromosome dynamics reveals locus-dependent dynamics and chromosome territory orientation. J Cell Sci 2023; 136:289470. [PMID: 36718642 PMCID: PMC10022681 DOI: 10.1242/jcs.260137] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 01/19/2023] [Indexed: 02/01/2023] Open
Abstract
Dynamic chromatin organization instantly influences DNA accessibility through modulating local macromolecular density and interactions, driving changes in transcription activities. Chromatin dynamics have been reported to be locally confined but contribute to coherent chromatin motion across the entire nucleus. However, the regulation of dynamics, nuclear orientation and compaction of subregions along a single chromosome are not well-understood. We used CRISPR-based real-time single-particle tracking and polymer models to characterize the dynamics of specific genomic loci and determine compaction levels of large human chromosomal domains. Our studies showed that chromosome compaction changed during interphase and that compactions of two arms on chromosome 19 were different. The dynamics of genomic loci were subdiffusive and dependent on chromosome regions and transcription states. Surprisingly, the correlation between locus-dependent nuclear localization and mobility was negligible. Strong tethering interactions detected at the pericentromeric region implies local condensation or associations with organelles within local nuclear microenvironments, such as chromatin-nuclear body association. Based on our findings, we propose a 'guided radial model' for the nuclear orientation of the long arm of chromosome 19.
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Affiliation(s)
- Yu-Chieh Chung
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Madhoolika Bisht
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Jenna Thuma
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Li-Chun Tu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
- Author for correspondence ()
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17
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Brückner DB, Chen H, Barinov L, Zoller B, Gregor T. Stochastic motion and transcriptional dynamics of pairs of distal DNA loci on a compacted chromosome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.18.524527. [PMID: 36711618 PMCID: PMC9882297 DOI: 10.1101/2023.01.18.524527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Chromosomes in the eukaryotic nucleus are highly compacted. However, for many functional processes, including transcription initiation, the 3D pair-wise motion of distal chromosomal elements, such as enhancers and promoters, is essential and necessitates dynamic fluidity. Therefore, the interplay of chromosome organization and dynamics is crucial for gene regulation. Here, we use a live imaging assay to simultaneously measure the positions of pairs of enhancers and promoters and their transcriptional output in the developing fly embryo while systematically varying the genomic separation between these two DNA loci. Our analysis reveals a combination of a compact globular organization and fast subdiffusive dynamics. These combined features cause an anomalous scaling of polymer relaxation times with genomic separation and lead to long-ranged correlations compared to existing polymer models. This scaling implies that encounter times of DNA loci are much less dependent on genomic separation than predicted by existing polymer models, with potentially significant consequences for eukaryotic gene expression.
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Affiliation(s)
- David B. Brückner
- Institute of Science and Technology, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Hongtao Chen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Lev Barinov
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Benjamin Zoller
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA
- Department of Developmental and Stem Cell Biology, CNRS UMR3738, Institut Pasteur, Paris, France
| | - Thomas Gregor
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA
- Department of Developmental and Stem Cell Biology, CNRS UMR3738, Institut Pasteur, Paris, France
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18
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Nair SJ, Suter T, Wang S, Yang L, Yang F, Rosenfeld MG. Transcriptional enhancers at 40: evolution of a viral DNA element to nuclear architectural structures. Trends Genet 2022; 38:1019-1047. [PMID: 35811173 PMCID: PMC9474616 DOI: 10.1016/j.tig.2022.05.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/05/2022] [Accepted: 05/31/2022] [Indexed: 02/08/2023]
Abstract
Gene regulation by transcriptional enhancers is the dominant mechanism driving cell type- and signal-specific transcriptional diversity in metazoans. However, over four decades since the original discovery, how enhancers operate in the nuclear space remains largely enigmatic. Recent multidisciplinary efforts combining real-time imaging, genome sequencing, and biophysical strategies provide insightful but conflicting models of enhancer-mediated gene control. Here, we review the discovery and progress in enhancer biology, emphasizing the recent findings that acutely activated enhancers assemble regulatory machinery as mesoscale architectural structures with distinct physical properties. These findings help formulate novel models that explain several mysterious features of the assembly of transcriptional enhancers and the mechanisms of spatial control of gene expression.
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Affiliation(s)
- Sreejith J Nair
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
| | - Tom Suter
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Susan Wang
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Cellular and Molecular Medicine Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lu Yang
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Feng Yang
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael G Rosenfeld
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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19
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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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20
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A proposed unified interphase nucleus chromosome structure: Preliminary preponderance of evidence. Proc Natl Acad Sci U S A 2022; 119:e2119101119. [PMID: 35749363 PMCID: PMC9245672 DOI: 10.1073/pnas.2119101119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cryopreservation of the nuclear interior allows a large-scale interphase chromosome structure—present throughout the nucleus—to be seen in its native state by electron tomography. This structure appears as a coiled chain of nucleosomes, wrapped like a Slinky toy. This coiled structure can be further used to explain the enigmatic architectures of polytene and lampbrush chromosomes. In addition, this new structure can further be organized as chromosome territories: for example, all 46 human interphase chromosomes easily fit into a 10-μm-diameter nucleus. Thus, interphase chromosomes can be unified into a flexibly defined structure. Cryoelectron tomography of the cell nucleus using scanning transmission electron microscopy and deconvolution processing technology has highlighted a large-scale, 100- to 300-nm interphase chromosome structure, which is present throughout the nucleus. This study further documents and analyzes these chromosome structures. The paper is divided into four parts: 1) evidence (preliminary) for a unified interphase chromosome structure; 2) a proposed unified interphase chromosome architecture; 3) organization as chromosome territories (e.g., fitting the 46 human chromosomes into a 10-μm-diameter nucleus); and 4) structure unification into a polytene chromosome architecture and lampbrush chromosomes. Finally, the paper concludes with a living light microscopy cell study showing that the G1 nucleus contains very similar structures throughout. The main finding is that this chromosome structure appears to coil the 11-nm nucleosome fiber into a defined hollow structure, analogous to a Slinky helical spring [https://en.wikipedia.org/wiki/Slinky; motif used in Bowerman et al., eLife 10, e65587 (2021)]. This Slinky architecture can be used to build chromosome territories, extended to the polytene chromosome structure, as well as to the structure of lampbrush chromosomes.
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21
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Popay TM, Dixon JR. Coming full circle: on the origin and evolution of the looping model for enhancer-promoter communication. J Biol Chem 2022; 298:102117. [PMID: 35691341 PMCID: PMC9283939 DOI: 10.1016/j.jbc.2022.102117] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/05/2022] Open
Abstract
In mammalian organisms, enhancers can regulate transcription from great genomic distances. How enhancers affect distal gene expression has been a major question in the field of gene regulation. One model to explain how enhancers communicate with their target promoters, the chromatin looping model, posits that enhancers and promoters come in close spatial proximity to mediate communication. Chromatin looping has been broadly accepted as a means for enhancer–promoter communication, driven by accumulating in vitro and in vivo evidence. The genome is now known to be folded into a complex 3D arrangement, created and maintained in part by the interplay of the Cohesin complex and the DNA-binding protein CTCF. In the last few years, however, doubt over the relationship between looping and transcriptional activation has emerged, driven by studies finding that only a modest number of genes are perturbed with acute degradation of looping machinery components. In parallel, newer models describing distal enhancer action have also come to prominence. In this article, we explore the emergence and development of the looping model as a means for enhancer–promoter communication and review the contrasting evidence between historical gene-specific and current global data for the role of chromatin looping in transcriptional regulation. We also discuss evidence for alternative models to chromatin looping and their support in the literature. We suggest that, while there is abundant evidence for chromatin looping as a major mechanism for enhancer function, enhancer–promoter communication is likely mediated by more than one mechanism in an enhancer- and context-dependent manner.
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Affiliation(s)
- Tessa M Popay
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Jesse R Dixon
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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22
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Nollmann M, Bennabi I, Götz M, Gregor T. The Impact of Space and Time on the Functional Output of the Genome. Cold Spring Harb Perspect Biol 2022; 14:a040378. [PMID: 34230036 PMCID: PMC8733053 DOI: 10.1101/cshperspect.a040378] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Over the past two decades, it has become clear that the multiscale spatial and temporal organization of the genome has important implications for nuclear function. This review centers on insights gained from recent advances in light microscopy on our understanding of transcription. We discuss spatial and temporal aspects that shape nuclear order and their consequences on regulatory components, focusing on genomic scales most relevant to function. The emerging picture is that spatiotemporal constraints increase the complexity in transcriptional regulation, highlighting new challenges, such as uncertainty about how information travels from molecular factors through the genome and space to generate a functional output.
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Affiliation(s)
- Marcelo Nollmann
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Isma Bennabi
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
| | - Markus Götz
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Thomas Gregor
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
- Joseph Henry Laboratory of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
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23
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Yesbolatova AK, Arai R, Sakaue T, Kimura A. Formulation of Chromatin Mobility as a Function of Nuclear Size during C. elegans Embryogenesis Using Polymer Physics Theories. PHYSICAL REVIEW LETTERS 2022; 128:178101. [PMID: 35570447 DOI: 10.1103/physrevlett.128.178101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 03/21/2022] [Indexed: 06/15/2023]
Abstract
During early embryogenesis of the nematode, Caenorhabditis elegans, the chromatin motion markedly decreases. Despite its biological implications, the underlying mechanism for this transition was unclear. By combining theory and experiment, we analyze the mean-square displacement (MSD) of the chromatin loci, and demonstrate that MSD-vs-time relationships in various nuclei collapse into a single master curve by normalizing them with the mesh size and the corresponding time scale. This enables us to identify the onset of the entangled dynamics with the size of tube diameter of chromatin polymer in the C. elegans embryo. Our dynamical scaling analysis predicts the transition between unentangled and entangled dynamics of chromatin polymers, the quantitative formula for MSD as a function of nuclear size and timescale, and provides testable hypotheses on chromatin mobility in other cell types and species.
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Affiliation(s)
- Aiya K Yesbolatova
- Department of Genetics, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, Mishima 411-8540, Japan
- Cell Architecture Laboratory, Department of Chromosome Science, National Institute of Genetics, Mishima 411-8540, Japan
| | - Ritsuko Arai
- Cell Architecture Laboratory, Department of Chromosome Science, National Institute of Genetics, Mishima 411-8540, Japan
| | - Takahiro Sakaue
- Department of Physical Sciences, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
| | - Akatsuki Kimura
- Department of Genetics, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, Mishima 411-8540, Japan
- Cell Architecture Laboratory, Department of Chromosome Science, National Institute of Genetics, Mishima 411-8540, Japan
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24
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Sensale S, Sharma P, Arya G. Binding kinetics of harmonically confined random walkers. Phys Rev E 2022; 105:044136. [PMID: 35590574 DOI: 10.1103/physreve.105.044136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 04/06/2022] [Indexed: 06/15/2023]
Abstract
Diffusion-mediated binding of molecules under the influence of discrete spatially confining potentials is a commonly encountered scenario in systems subjected to explicit fields or implicit fields arising from tethering restraints. Here, we derive analytical expressions for the mean binding time of two random walkers geometrically confined by means of two harmonic potentials in one- and two-dimensional systems, which show excellent agreement with Brownian dynamics simulations. As a demonstration of its utility, we use this theory to maximize the communication speed in existing DNA walkers, obtaining quantitative agreement with previously reported experimental findings. The analytical expressions derived in this paper are broadly applicable to diverse systems, providing ways to characterize communication processes and optimize the rate of signal propagation for sensing and computing applications at the nanoscale.
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Affiliation(s)
- Sebastian Sensale
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
| | - Pranav Sharma
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
| | - Gaurav Arya
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
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25
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Delker RK, Munce RH, Hu M, Mann RS. Fluorescent labeling of genomic loci in Drosophila imaginal discs with heterologous DNA-binding proteins. CELL REPORTS METHODS 2022; 2:100175. [PMID: 35475221 PMCID: PMC9017127 DOI: 10.1016/j.crmeth.2022.100175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/02/2021] [Accepted: 02/11/2022] [Indexed: 11/25/2022]
Abstract
Using the Drosophila melanogaster Hox gene Ultrabithorax (Ubx) as an example, we demonstrate the use of three heterologous DNA-binding protein systems-LacI/LacO, ParB1/ParS1, and ParB2/ParS2-to label genomic loci in imaginal discs with the insertion of a small DNA tag. We compare each system, considering the impact of labeling in genomic regions (1) inside versus outside of a transcribed gene body and (2) with varying chromatin accessibility. We demonstrate the value of this system by interrogating the relationship between gene expression level and enhancer-promoter distance, as well as inter-allelic distance at the Ubx locus. We find that the distance between an essential intronic cis-regulatory element, anterobithorax (abx), and the promoter does not vary with expression level. In contrast, inter-allelic distance correlates with Ubx expression level.
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Affiliation(s)
- Rebecca K. Delker
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Ross H. Munce
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Michelle Hu
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Richard S. Mann
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- Department of Neuroscience, Columbia University Irving Medical Center, New York, NY, USA
- Department of Systems Biology, Columbia University Irving Medical Center, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
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26
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Brandstetter K, Zülske T, Ragoczy T, Hörl D, Guirao-Ortiz M, Steinek C, Barnes T, Stumberger G, Schwach J, Haugen E, Rynes E, Korber P, Stamatoyannopoulos JA, Leonhardt H, Wedemann G, Harz H. Differences in nanoscale organization of regulatory active and inactive human chromatin. Biophys J 2022; 121:977-990. [PMID: 35150617 PMCID: PMC8943813 DOI: 10.1016/j.bpj.2022.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 12/11/2021] [Accepted: 02/07/2022] [Indexed: 11/25/2022] Open
Abstract
Methodological advances in conformation capture techniques have fundamentally changed our understanding of chromatin architecture. However, the nanoscale organization of chromatin and its cell-to-cell variance are less studied. Analyzing genome-wide data from 733 human cell and tissue samples, we identified 2 prototypical regions that exhibit high or absent hypersensitivity to deoxyribonuclease I, respectively. These regulatory active or inactive regions were examined in the lymphoblast cell line K562 by using high-throughput super-resolution microscopy. In both regions, we systematically measured the physical distance of 2 fluorescence in situ hybridization spots spaced by only 5 kb of DNA. Unexpectedly, the resulting distance distributions range from very compact to almost elongated configurations of more than 200-nm length for both the active and inactive regions. Monte Carlo simulations of a coarse-grained model of these chromatin regions based on published data of nucleosome occupancy in K562 cells were performed to understand the underlying mechanisms. There was no parameter set for the simulation model that can explain the microscopically measured distance distributions. Obviously, the chromatin state given by the strength of internucleosomal interaction, nucleosome occupancy, or amount of histone H1 differs from cell to cell, which results in the observed broad distance distributions. This large variability was not expected, especially in inactive regions. The results for the mechanisms for different distance distributions on this scale are important for understanding the contacts that mediate gene regulation. Microscopic measurements show that the inactive region investigated here is expected to be embedded in a more compact chromatin environment. The simulation results of this region require an increase in the strength of internucleosomal interactions. It may be speculated that the higher density of chromatin is caused by the increased internucleosomal interaction strength.
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Affiliation(s)
- Katharina Brandstetter
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Tilo Zülske
- Competence Center Bioinformatics, Institute for Applied Computer Science, Hochschule Stralsund, Stralsund, Germany
| | - Tobias Ragoczy
- Altius Institute for Biomedical Sciences, Seattle, Washington
| | - David Hörl
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Miguel Guirao-Ortiz
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Clemens Steinek
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Toby Barnes
- Biomedical Center (BMC), Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Gabriela Stumberger
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jonathan Schwach
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Eric Haugen
- Altius Institute for Biomedical Sciences, Seattle, Washington
| | - Eric Rynes
- Altius Institute for Biomedical Sciences, Seattle, Washington
| | - Philipp Korber
- Biomedical Center (BMC), Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - John A Stamatoyannopoulos
- Altius Institute for Biomedical Sciences, Seattle, Washington; Department of Genome Sciences, University of Washington, Seattle, Washington; Department of Medicine, Division of Oncology, University of Washington, Seattle, Washington
| | - Heinrich Leonhardt
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Gero Wedemann
- Competence Center Bioinformatics, Institute for Applied Computer Science, Hochschule Stralsund, Stralsund, Germany.
| | - Hartmann Harz
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany.
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27
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Leidescher S, Ribisel J, Ullrich S, Feodorova Y, Hildebrand E, Galitsyna A, Bultmann S, Link S, Thanisch K, Mulholland C, Dekker J, Leonhardt H, Mirny L, Solovei I. Spatial organization of transcribed eukaryotic genes. Nat Cell Biol 2022; 24:327-339. [PMID: 35177821 DOI: 10.1038/s41556-022-00847-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 01/10/2022] [Indexed: 12/19/2022]
Abstract
Despite the well-established role of nuclear organization in the regulation of gene expression, little is known about the reverse: how transcription shapes the spatial organization of the genome. Owing to the small sizes of most previously studied genes and the limited resolution of microscopy, the structure and spatial arrangement of a single transcribed gene are still poorly understood. Here we study several long highly expressed genes and demonstrate that they form open-ended transcription loops with polymerases moving along the loops and carrying nascent RNAs. Transcription loops can span across micrometres, resembling lampbrush loops and polytene puffs. The extension and shape of transcription loops suggest their intrinsic stiffness, which we attribute to decoration with multiple voluminous nascent ribonucleoproteins. Our data contradict the model of transcription factories and suggest that although microscopically resolvable transcription loops are specific for long highly expressed genes, the mechanisms underlying their formation could represent a general aspect of eukaryotic transcription.
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Affiliation(s)
- Susanne Leidescher
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Johannes Ribisel
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Simon Ullrich
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Yana Feodorova
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.,Department of Medical Biology, Medical University of Plovdiv; Division of Molecular and Regenerative Medicine, Research Institute at Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Erica Hildebrand
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Sebastian Bultmann
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Stephanie Link
- BioMedizinisches Center, Ludwig-Maximilians University Munich, Planegg-Martinsried, Germany
| | - Katharina Thanisch
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.,Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Christopher Mulholland
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Heinrich Leonhardt
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Leonid Mirny
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Irina Solovei
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.
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28
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Uchino S, Ito Y, Sato Y, Handa T, Ohkawa Y, Tokunaga M, Kimura H. Live imaging of transcription sites using an elongating RNA polymerase II-specific probe. J Cell Biol 2022; 221:212888. [PMID: 34854870 PMCID: PMC8647360 DOI: 10.1083/jcb.202104134] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 10/12/2021] [Accepted: 11/10/2021] [Indexed: 12/15/2022] Open
Abstract
In eukaryotic nuclei, most genes are transcribed by RNA polymerase II (RNAP2), whose regulation is a key to understanding the genome and cell function. RNAP2 has a long heptapeptide repeat (Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), and Ser2 is phosphorylated on an elongation form. To detect RNAP2 Ser2 phosphorylation (RNAP2 Ser2ph) in living cells, we developed a genetically encoded modification-specific intracellular antibody (mintbody) probe. The RNAP2 Ser2ph-mintbody exhibited numerous foci, possibly representing transcription “factories,” and foci were diminished during mitosis and in a Ser2 kinase inhibitor. An in vitro binding assay using phosphopeptides confirmed the mintbody’s specificity. RNAP2 Ser2ph-mintbody foci were colocalized with proteins associated with elongating RNAP2 compared with factors involved in the initiation. These results support the view that mintbody localization represents the sites of RNAP2 Ser2ph in living cells. RNAP2 Ser2ph-mintbody foci showed constrained diffusional motion like chromatin, but they were more mobile than DNA replication domains and p300-enriched foci, suggesting that the elongating RNAP2 complexes are separated from more confined chromatin domains.
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Affiliation(s)
- Satoshi Uchino
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Yuma Ito
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Yuko Sato
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.,Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Tetsuya Handa
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Yasuyuki Ohkawa
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Makio Tokunaga
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Hiroshi Kimura
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.,Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
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29
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Laghmach R, Di Pierro M, Potoyan D. A Liquid State Perspective on Dynamics of Chromatin Compartments. Front Mol Biosci 2022; 8:781981. [PMID: 35096966 PMCID: PMC8793688 DOI: 10.3389/fmolb.2021.781981] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 12/22/2021] [Indexed: 12/11/2022] Open
Abstract
The interior of the eukaryotic cell nucleus has a crowded and heterogeneous environment packed with chromatin polymers, regulatory proteins, and RNA molecules. Chromatin polymer, assisted by epigenetic modifications, protein and RNA binders, forms multi-scale compartments which help regulate genes in response to cellular signals. Furthermore, chromatin compartments are dynamic and tend to evolve in size and composition in ways that are not fully understood. The latest super-resolution imaging experiments have revealed a much more dynamic and stochastic nature of chromatin compartments than was appreciated before. An emerging mechanism explaining chromatin compartmentalization dynamics is the phase separation of protein and nucleic acids into membraneless liquid condensates. Consequently, concepts and ideas from soft matter and polymer systems have been rapidly entering the lexicon of cell biology. In this respect, the role of computational models is crucial for establishing a rigorous and quantitative foundation for the new concepts and disentangling the complex interplay of forces that contribute to the emergent patterns of chromatin dynamics and organization. Several multi-scale models have emerged to address various aspects of chromatin dynamics, ranging from equilibrium polymer simulations, hybrid non-equilibrium simulations coupling protein binding and chromatin folding, and mesoscopic field-theoretic models. Here, we review these emerging theoretical paradigms and computational models with a particular focus on chromatin’s phase separation and liquid-like properties as a basis for nuclear organization and dynamics.
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Affiliation(s)
- Rabia Laghmach
- Department of Chemistry, Iowa State University, Ames, IA, United States
| | - Michele Di Pierro
- Department of Physics, Northeastern University, Boston, MA, United States
| | - Davit Potoyan
- Department of Chemistry, Iowa State University, Ames, IA, United States
- *Correspondence: Davit Potoyan,
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30
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Johanson TM, Keenan CR, Allan RS. Shedding Structured Light on Molecular Immunity: The Past, Present and Future of Immune Cell Super Resolution Microscopy. Front Immunol 2021; 12:754200. [PMID: 34975842 PMCID: PMC8715013 DOI: 10.3389/fimmu.2021.754200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/23/2021] [Indexed: 12/16/2022] Open
Abstract
In the two decades since the invention of laser-based super resolution microscopy this family of technologies has revolutionised the way life is viewed and understood. Its unparalleled resolution, speed, and accessibility makes super resolution imaging particularly useful in examining the highly complex and dynamic immune system. Here we introduce the super resolution technologies and studies that have already fundamentally changed our understanding of a number of central immunological processes and highlight other immunological puzzles only addressable in super resolution.
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Affiliation(s)
- Timothy M. Johanson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Christine R. Keenan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Rhys S. Allan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
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31
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Abstract
Nuclear bodies are membraneless condensates that may form via liquid-liquid phase separation. The viscoelastic chromatin network could impact their stability and may hold the key for understanding experimental observations that defy predictions of classical theories. However, quantitative studies on the role of the chromatin network in phase separation have remained challenging. Using a diploid human genome model parameterized with chromosome conformation capture (Hi-C) data, we study the thermodynamics and kinetics of nucleoli formation. Dynamical simulations predict the formation of multiple droplets for nucleolar particles that experience specific interactions with nucleolus-associated domains (NADs). Coarsening dynamics, surface tension, and coalescence kinetics of the simulated droplets are all in quantitative agreement with experimental measurements for nucleoli. Free energy calculations further support that a two-droplet state, often observed for nucleoli in somatic cells, is metastable and separated from the single-droplet state with an entropic barrier. Our study suggests that nucleoli-chromatin interactions facilitate droplets' nucleation but hinder their coarsening due to the coupled motion between droplets and the chromatin network: as droplets coalesce, the chromatin network becomes increasingly constrained. Therefore, the chromatin network supports a nucleation and arrest mechanism to stabilize the multi-droplet state for nucleoli and possibly for other nuclear bodies.
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32
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Laghmach R, Di Pierro M, Potoyan DA. The interplay of chromatin phase separation and lamina interactions in nuclear organization. Biophys J 2021; 120:5005-5017. [PMID: 34653387 DOI: 10.1016/j.bpj.2021.10.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/28/2021] [Accepted: 10/08/2021] [Indexed: 12/12/2022] Open
Abstract
The genetic material of eukaryotes is segregated into transcriptionally active euchromatin and silent heterochromatin compartments. The spatial arrangement of chromatin compartments evolves over the course of cellular life in a process that remains poorly understood. The latest nuclear imaging experiments reveal a number of dynamical signatures of chromatin that are reminiscent of active multiphase liquids. This includes the observations of viscoelastic response, coherent motions, Ostwald ripening, and coalescence of chromatin compartments. There is also growing evidence that liquid-liquid phase separation of protein and nucleic acid components is the underlying mechanism for the dynamical behavior of chromatin. To dissect the organizational and dynamical implications of chromatin's liquid behavior, we have devised a phenomenological field-theoretic model of the nucleus as a multiphase condensate of liquid chromatin types. Employing the liquid chromatin model of the Drosophila nucleus, we have carried out an extensive set of simulations with an objective to shed light on the dynamics and chromatin patterning observed in the latest nuclear imaging experiments. Our simulations reveal the emergence of experimentally detected mesoscale chromatin channels and spheroidal droplets which arise from the dynamic interplay of chromatin type to type interactions and intermingling of chromosomal territories. We also quantitatively reproduce coherent motions of chromatin domains observed in displacement correlation spectroscopy measurements which are explained within the framework of our model by phase separation of chromatin types operating within constrained intrachromosomal and interchromosomal boundaries. Finally, we illuminate the role of heterochromatin-lamina interactions in the nuclear organization by showing that these interactions enhance the mobility of euchromatin and indirectly introduce correlated motions of heterochromatin droplets.
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Affiliation(s)
- Rabia Laghmach
- Department of Chemistry, Iowa State University, Ames, Iowa.
| | - Michele Di Pierro
- Department of Physics, Northeastern University, Boston, Massachusetts
| | - Davit A Potoyan
- Department of Chemistry, Iowa State University, Ames, Iowa; Department of Biochemistry and Molecular Biology, Ames, Iowa; Bioinformatics and Computational Biology Program, Iowa State University, Ames, Iowa.
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33
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Frock RL, Sadeghi C, Meng J, Wang JL. DNA End Joining: G0-ing to the Core. Biomolecules 2021; 11:biom11101487. [PMID: 34680120 PMCID: PMC8533500 DOI: 10.3390/biom11101487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 12/28/2022] Open
Abstract
Humans have evolved a series of DNA double-strand break (DSB) repair pathways to efficiently and accurately rejoin nascently formed pairs of double-stranded DNA ends (DSEs). In G0/G1-phase cells, non-homologous end joining (NHEJ) and alternative end joining (A-EJ) operate to support covalent rejoining of DSEs. While NHEJ is predominantly utilized and collaborates extensively with the DNA damage response (DDR) to support pairing of DSEs, much less is known about A-EJ collaboration with DDR factors when NHEJ is absent. Non-cycling lymphocyte progenitor cells use NHEJ to complete V(D)J recombination of antigen receptor genes, initiated by the RAG1/2 endonuclease which holds its pair of targeted DSBs in a synapse until each specified pair of DSEs is handed off to the NHEJ DSB sensor complex, Ku. Similar to designer endonuclease DSBs, the absence of Ku allows for A-EJ to access RAG1/2 DSEs but with random pairing to complete their repair. Here, we describe recent insights into the major phases of DSB end joining, with an emphasis on synapsis and tethering mechanisms, and bring together new and old concepts of NHEJ vs. A-EJ and on RAG2-mediated repair pathway choice.
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34
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Jerkovic I, Cavalli G. Understanding 3D genome organization by multidisciplinary methods. Nat Rev Mol Cell Biol 2021; 22:511-528. [PMID: 33953379 DOI: 10.1038/s41580-021-00362-w] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2021] [Indexed: 02/03/2023]
Abstract
Understanding how chromatin is folded in the nucleus is fundamental to understanding its function. Although 3D genome organization has been historically difficult to study owing to a lack of relevant methodologies, major technological breakthroughs in genome-wide mapping of chromatin contacts and advances in imaging technologies in the twenty-first century considerably improved our understanding of chromosome conformation and nuclear architecture. In this Review, we discuss methods of 3D genome organization analysis, including sequencing-based techniques, such as Hi-C and its derivatives, Micro-C, DamID and others; microscopy-based techniques, such as super-resolution imaging coupled with fluorescence in situ hybridization (FISH), multiplex FISH, in situ genome sequencing and live microscopy methods; and computational and modelling approaches. We describe the most commonly used techniques and their contribution to our current knowledge of nuclear architecture and, finally, we provide a perspective on up-and-coming methods that open possibilities for future major discoveries.
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Affiliation(s)
- Ivana Jerkovic
- Institute of Human Genetics, CNRS, University of Montpellier, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, CNRS, University of Montpellier, Montpellier, France.
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35
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Lin X, Qi Y, Latham AP, Zhang B. Multiscale modeling of genome organization with maximum entropy optimization. J Chem Phys 2021; 155:010901. [PMID: 34241389 PMCID: PMC8253599 DOI: 10.1063/5.0044150] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 04/28/2021] [Indexed: 12/15/2022] Open
Abstract
Three-dimensional (3D) organization of the human genome plays an essential role in all DNA-templated processes, including gene transcription, gene regulation, and DNA replication. Computational modeling can be an effective way of building high-resolution genome structures and improving our understanding of these molecular processes. However, it faces significant challenges as the human genome consists of over 6 × 109 base pairs, a system size that exceeds the capacity of traditional modeling approaches. In this perspective, we review the progress that has been made in modeling the human genome. Coarse-grained models parameterized to reproduce experimental data via the maximum entropy optimization algorithm serve as effective means to study genome organization at various length scales. They have provided insight into the principles of whole-genome organization and enabled de novo predictions of chromosome structures from epigenetic modifications. Applications of these models at a near-atomistic resolution further revealed physicochemical interactions that drive the phase separation of disordered proteins and dictate chromatin stability in situ. We conclude with an outlook on the opportunities and challenges in studying chromosome dynamics.
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Affiliation(s)
- Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yifeng Qi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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36
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Xie L, Liu Z. Single-cell imaging of genome organization and dynamics. Mol Syst Biol 2021; 17:e9653. [PMID: 34232558 PMCID: PMC8262488 DOI: 10.15252/msb.20209653] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/13/2021] [Accepted: 04/23/2021] [Indexed: 12/28/2022] Open
Abstract
Probing the architecture, mechanism, and dynamics of genome folding is fundamental to our understanding of genome function in homeostasis and disease. Most chromosome conformation capture studies dissect the genome architecture with population- and time-averaged snapshots and thus have limited capabilities to reveal 3D nuclear organization and dynamics at the single-cell level. Here, we discuss emerging imaging techniques ranging from light microscopy to electron microscopy that enable investigation of genome folding and dynamics at high spatial and temporal resolution. Results from these studies complement genomic data, unveiling principles underlying the spatial arrangement of the genome and its potential functional links to diverse biological activities in the nucleus.
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Affiliation(s)
- Liangqi Xie
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
| | - Zhe Liu
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
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37
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Oh S, Shao J, Mitra J, Xiong F, D'Antonio M, Wang R, Garcia-Bassets I, Ma Q, Zhu X, Lee JH, Nair SJ, Yang F, Ohgi K, Frazer KA, Zhang ZD, Li W, Rosenfeld MG. Enhancer release and retargeting activates disease-susceptibility genes. Nature 2021; 595:735-740. [PMID: 34040254 PMCID: PMC11171441 DOI: 10.1038/s41586-021-03577-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 04/23/2021] [Indexed: 02/04/2023]
Abstract
The functional engagement between an enhancer and its target promoter ensures precise gene transcription1. Understanding the basis of promoter choice by enhancers has important implications for health and disease. Here we report that functional loss of a preferred promoter can release its partner enhancer to loop to and activate an alternative promoter (or alternative promoters) in the neighbourhood. We refer to this target-switching process as 'enhancer release and retargeting'. Genetic deletion, motif perturbation or mutation, and dCas9-mediated CTCF tethering reveal that promoter choice by an enhancer can be determined by the binding of CTCF at promoters, in a cohesin-dependent manner-consistent with a model of 'enhancer scanning' inside the contact domain. Promoter-associated CTCF shows a lower affinity than that at chromatin domain boundaries and often lacks a preferred motif orientation or a partnering CTCF at the cognate enhancer, suggesting properties distinct from boundary CTCF. Analyses of cancer mutations, data from the GTEx project and risk loci from genome-wide association studies, together with a focused CRISPR interference screen, reveal that enhancer release and retargeting represents an overlooked mechanism that underlies the activation of disease-susceptibility genes, as exemplified by a risk locus for Parkinson's disease (NUCKS1-RAB7L1) and three loci associated with cancer (CLPTM1L-TERT, ZCCHC7-PAX5 and PVT1-MYC).
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Affiliation(s)
- Soohwan Oh
- Howard Hughes Medical Institute, Department and School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Jiaofang Shao
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Joydeep Mitra
- Department of Genetics, Albert Einstein College of Medicine, New York, NY, USA
| | - Feng Xiong
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Matteo D'Antonio
- Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Ruoyu Wang
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
- Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and UTHealth, Houston, TX, USA
| | - Ivan Garcia-Bassets
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Qi Ma
- Howard Hughes Medical Institute, Department and School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Xiaoyu Zhu
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Joo-Hyung Lee
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Sreejith J Nair
- Howard Hughes Medical Institute, Department and School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Feng Yang
- Howard Hughes Medical Institute, Department and School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Kenneth Ohgi
- Howard Hughes Medical Institute, Department and School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Kelly A Frazer
- Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA, USA
- Institute for Genomic Medicine, University of California San Diego, La Jolla, CA, USA
| | - Zhengdong D Zhang
- Department of Genetics, Albert Einstein College of Medicine, New York, NY, USA
| | - Wenbo Li
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA.
- Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and UTHealth, Houston, TX, USA.
| | - Michael G Rosenfeld
- Howard Hughes Medical Institute, Department and School of Medicine, University of California San Diego, La Jolla, CA, USA.
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38
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Geng Y, Pertsinidis A. Simple and versatile imaging of genomic loci in live mammalian cells and early pre-implantation embryos using CAS-LiveFISH. Sci Rep 2021; 11:12220. [PMID: 34108610 PMCID: PMC8190065 DOI: 10.1038/s41598-021-91787-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/01/2021] [Indexed: 11/14/2022] Open
Abstract
Visualizing the 4D genome in live cells is essential for understanding its regulation. Programmable DNA-binding probes, such as fluorescent clustered regularly interspaced short palindromic repeats (CRISPR) and transcription activator-like effector (TALE) proteins have recently emerged as powerful tools for imaging specific genomic loci in live cells. However, many such systems rely on genetically-encoded components, often requiring multiple constructs that each must be separately optimized, thus limiting their use. Here we develop efficient and versatile systems, based on in vitro transcribed single-guide-RNAs (sgRNAs) and fluorescently-tagged recombinant, catalytically-inactivated Cas9 (dCas9) proteins. Controlled cell delivery of pre-assembled dCas9-sgRNA ribonucleoprotein (RNP) complexes enables robust genomic imaging in live cells and in early mouse embryos. We further demonstrate multiplex tagging of up to 3 genes, tracking detailed movements of chromatin segments and imaging spatial relationships between a distal enhancer and a target gene, with nanometer resolution in live cells. This simple and effective approach should facilitate visualizing chromatin dynamics and nuclear architecture in various living systems.
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Affiliation(s)
- Yongtao Geng
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Alexandros Pertsinidis
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.
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39
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Kenter AL, Watson CT, Spille JH. Igh Locus Polymorphism May Dictate Topological Chromatin Conformation and V Gene Usage in the Ig Repertoire. Front Immunol 2021; 12:682589. [PMID: 34084176 PMCID: PMC8167033 DOI: 10.3389/fimmu.2021.682589] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 04/26/2021] [Indexed: 01/08/2023] Open
Abstract
Vast repertoires of unique antigen receptors are created in developing B and T lymphocytes. The antigen receptor loci contain many variable (V), diversity (D) and joining (J) gene segments that are arrayed across very large genomic expanses and are joined to form variable-region exons of expressed immunoglobulins and T cell receptors. This process creates the potential for an organism to respond to large numbers of different pathogens. Here, we consider the possibility that genetic polymorphisms with alterations in a vast array of regulatory elements in the immunoglobulin heavy chain (IgH) locus lead to changes in locus topology and impact immune-repertoire formation.
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Affiliation(s)
- Amy L. Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL, United States
| | - Corey T. Watson
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY, United States
| | - Jan-Hendrik Spille
- Department of Physics, University of Illinois at Chicago, Chicago, IL, United States
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40
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Sumner MC, Torrisi SB, Brickner DG, Brickner JH. Random sub-diffusion and capture of genes by the nuclear pore reduces dynamics and coordinates inter-chromosomal movement. eLife 2021; 10:66238. [PMID: 34002694 PMCID: PMC8195609 DOI: 10.7554/elife.66238] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/17/2021] [Indexed: 11/13/2022] Open
Abstract
Hundreds of genes interact with the yeast nuclear pore complex (NPC), localizing at the nuclear periphery and clustering with co-regulated genes. Dynamic tracking of peripheral genes shows that they cycle on and off the NPC and that interaction with the NPC slows their sub-diffusive movement. Furthermore, NPC-dependent inter-chromosomal clustering leads to coordinated movement of pairs of loci separated by hundreds of nanometers. We developed fractional Brownian motion simulations for chromosomal loci in the nucleoplasm and interacting with NPCs. These simulations predict the rate and nature of random sub-diffusion during repositioning from nucleoplasm to periphery and match measurements from two different experimental models, arguing that recruitment to the nuclear periphery is due to random sub-diffusion and transient capture by NPCs. Finally, the simulations do not lead to inter-chromosomal clustering or coordinated movement, suggesting that interaction with the NPC is necessary, but not sufficient, to cause clustering.
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Affiliation(s)
- Michael Chas Sumner
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Steven B Torrisi
- Department of Physics, Harvard University, Cambridge, United States
| | - Donna G Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Jason H Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
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41
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Qi Y, Warmenhoven JW, Henthorn NT, Ingram SP, Xu XG, Kirkby KJ, Merchant MJ. Mechanistic Modelling of Slow and Fast NHEJ DNA Repair Pathways Following Radiation for G0/G1 Normal Tissue Cells. Cancers (Basel) 2021; 13:2202. [PMID: 34063683 PMCID: PMC8124137 DOI: 10.3390/cancers13092202] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/23/2021] [Accepted: 04/29/2021] [Indexed: 01/12/2023] Open
Abstract
Mechanistic in silico models can provide insight into biological mechanisms and highlight uncertainties for experimental investigation. Radiation-induced double-strand breaks (DSBs) are known to be toxic lesions if not repaired correctly. Non-homologous end joining (NHEJ) is the major DSB-repair pathway available throughout the cell cycle and, recently, has been hypothesised to consist of a fast and slow component in G0/G1. The slow component has been shown to be resection-dependent, requiring the nuclease Artemis to function. However, the pathway is not yet fully understood. This study compares two hypothesised models, simulating the action of individual repair proteins on DSB ends in a step-by-step manner, enabling the modelling of both wild-type and protein-deficient cell systems. Performance is benchmarked against experimental data from 21 cell lines and 18 radiation qualities. A model where resection-dependent and independent pathways are entirely separated can only reproduce experimental repair kinetics with additional restraints on end motion and protein recruitment. However, a model where the pathways are entwined was found to effectively fit without needing additional mechanisms. It has been shown that DaMaRiS is a useful tool when analysing the connections between resection-dependent and independent NHEJ repair pathways and robustly matches with experimental results from several sources.
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Affiliation(s)
- Yaping Qi
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China;
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
| | - John William Warmenhoven
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| | - Nicholas Thomas Henthorn
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| | - Samuel Peter Ingram
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester M13 9PL, UK
| | - Xie George Xu
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China;
| | - Karen Joy Kirkby
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| | - Michael John Merchant
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (J.W.W.); (N.T.H.); (S.P.I.); (K.J.K.); (M.J.M.)
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
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42
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Liu S, Zhao K. The Toolbox for Untangling Chromosome Architecture in Immune Cells. Front Immunol 2021; 12:670884. [PMID: 33995409 PMCID: PMC8120992 DOI: 10.3389/fimmu.2021.670884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/06/2021] [Indexed: 12/19/2022] Open
Abstract
The code of life is not only encrypted in the sequence of DNA but also in the way it is organized into chromosomes. Chromosome architecture is gradually being recognized as an important player in regulating cell activities (e.g., controlling spatiotemporal gene expression). In the past decade, the toolbox for elucidating genome structure has been expanding, providing an opportunity to explore this under charted territory. In this review, we will introduce the recent advancements in approaches for mapping spatial organization of the genome, emphasizing applications of these techniques to immune cells, and trying to bridge chromosome structure with immune cell activities.
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Affiliation(s)
- Shuai Liu
- Laboratory of Epigenome Biology, Systems Biology Center, NHLBI, NIH, Bethesda, MD, United States
| | - Keji Zhao
- Laboratory of Epigenome Biology, Systems Biology Center, NHLBI, NIH, Bethesda, MD, United States
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43
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Pongubala JMR, Murre C. Spatial Organization of Chromatin: Transcriptional Control of Adaptive Immune Cell Development. Front Immunol 2021; 12:633825. [PMID: 33854505 PMCID: PMC8039525 DOI: 10.3389/fimmu.2021.633825] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/03/2021] [Indexed: 12/11/2022] Open
Abstract
Higher-order spatial organization of the genome into chromatin compartments (permissive and repressive), self-associating domains (TADs), and regulatory loops provides structural integrity and offers diverse gene regulatory controls. In particular, chromatin regulatory loops, which bring enhancer and associated transcription factors in close spatial proximity to target gene promoters, play essential roles in regulating gene expression. The establishment and maintenance of such chromatin loops are predominantly mediated involving CTCF and the cohesin machinery. In recent years, significant progress has been made in revealing how loops are assembled and how they modulate patterns of gene expression. Here we will discuss the mechanistic principles that underpin the establishment of three-dimensional (3D) chromatin structure and how changes in chromatin structure relate to alterations in gene programs that establish immune cell fate.
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Affiliation(s)
| | - Cornelis Murre
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States
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44
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Martínez de Paz A, Josefowicz SZ. Signaling-to-chromatin pathways in the immune system. Immunol Rev 2021; 300:37-53. [PMID: 33644906 PMCID: PMC8548991 DOI: 10.1111/imr.12955] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 02/01/2023]
Abstract
Complex organisms are able to respond to diverse environmental cues by rapidly inducing specific transcriptional programs comprising a few dozen genes among thousands. The highly complex environment within the nucleus-a crowded milieu containing large genomes tightly condensed with histone proteins in the form of chromatin-makes inducible transcription a challenge for the cell, akin to the proverbial needle in a haystack. The different signaling pathways and transcription factors involved in the transmission of information from the cell surface to the nucleus have been readily explored, but not so much the specific mechanisms employed by the cell to ultimately instruct the chromatin changes necessary for a fast and robust transcription activation. Signaling pathways rely on cascades of protein kinases that, in addition to activating transcription factors can also activate the chromatin template by phosphorylating histone proteins, what we refer to as "signaling-to-chromatin." These pathways appear to be selectively employed and especially critical for driving inducible transcription in macrophages and likely in diverse other immune cell populations. Here, we discuss signaling-to-chromatin pathways with potential relevance in diverse immune cell populations together with chromatin related mechanisms that help to "solve" the needle in a haystack challenge of robust chromatin activation and inducible transcription.
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Affiliation(s)
- Alexia Martínez de Paz
- Laboratory of Epigenetics and Immunity, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Steven Zvi Josefowicz
- Laboratory of Epigenetics and Immunity, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
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45
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Shim SH. Super-resolution microscopy of genome organization. Genes Genomics 2021; 43:281-287. [PMID: 33630271 DOI: 10.1007/s13258-021-01044-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 01/06/2021] [Indexed: 12/31/2022]
Abstract
Recent advancements in sequencing and imaging technologies are providing new perspectives in solving the mystery of three-dimensional folding of genome in a nucleus. Chromosome conformation capture sequencing has discovered new chromatin structures such as topologically associated domains and loops in hundreds of kilobases. Super-resolution fluorescence microscopy with nanometer resolutions, in particular multiplexed approaches with sequence-specificity, has visualized chromatin structures from the rough folds of whole chromosomes to the fine loops of cis-regulatory elements in intact individual nuclei. Here, recent advancements in genome visualization tools with highly multiplexed labeling and reading are introduced. These imaging technologies have found ensemble behavior consistent to sequencing results, while unveiling single-cell variations. But, they also generated contradictory results on the roles of architectural proteins (like cohesion and CTCF) and enhancer-promoter interactions. Live-cell labeling methods for imaging specific genomic loci, especially the CRISPR/dCas9 system, are reviewed in order to give perspectives in the emergence of tools for visualizing genome structural dynamics.
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Affiliation(s)
- Sang-Hee Shim
- Department of Chemistry, Korea University, Seoul, 02481, Korea.
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46
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Liu X, Sun Q, Wang Q, Hu C, Chen X, Li H, Czajkowsky DM, Shao Z. Epithelial Cells in 2D and 3D Cultures Exhibit Large Differences in Higher-order Genomic Interactions. GENOMICS PROTEOMICS & BIOINFORMATICS 2021; 20:101-109. [PMID: 33631432 PMCID: PMC9510857 DOI: 10.1016/j.gpb.2020.06.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 03/09/2020] [Accepted: 08/09/2020] [Indexed: 02/07/2023]
Abstract
Recent studies have characterized the genomic structures of many eukaryotic cells, often focusing on their relation to gene expression. However, these studies have largely investigated cells grown in 2D cultures, although the transcriptomes of 3D-cultured cells are generally closer to their in vivo phenotypes. To examine the effects of spatial constraints on chromosome conformation, we investigated the genomic architecture of mouse hepatocytes grown in 2D and 3D cultures using in situ Hi-C. Our results reveal significant differences in higher-order genomic interactions, notably in compartment identity and strength as well as in topologically associating domain (TAD)–TAD interactions, but only minor differences are found at the TAD level. Our RNA-seq analysis reveals an up-regulated expression of genes involved in physiological hepatocyte functions in the 3D-cultured cells. These genes are associated with a subset of structural changes, suggesting that differences in genomic structure are critically important for transcriptional regulation. However, there are also many structural differences that are not directly associated with changes in gene expression, whose cause remains to be determined. Overall, our results indicate that growth in 3D significantly alters higher-order genomic interactions, which may be consequential for a subset of genes that are important for the physiological functioning of the cell.
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Affiliation(s)
- Xin Liu
- State Key Laboratory for Oncogenes and Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qiu Sun
- Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qi Wang
- Translational Medical Center for Stem Cell Therapy & Institute for Regenerative Medicine, Shanghai East Hospital, School of Life Science and Technology, Shanghai Key Laboratory of Signaling and Disease Research, Tongji University, Shanghai 200092, China
| | - Chuansheng Hu
- State Key Laboratory for Oncogenes and Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xuecheng Chen
- Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hua Li
- State Key Laboratory for Oncogenes and Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Daniel M Czajkowsky
- State Key Laboratory for Oncogenes and Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Zhifeng Shao
- State Key Laboratory for Oncogenes and Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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47
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Rogers CH, Mielczarek O, Corcoran AE. Dynamic 3D Locus Organization and Its Drivers Underpin Immunoglobulin Recombination. Front Immunol 2021; 11:633705. [PMID: 33679727 PMCID: PMC7930373 DOI: 10.3389/fimmu.2020.633705] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 12/30/2020] [Indexed: 01/10/2023] Open
Abstract
A functional adaptive immune system must generate enormously diverse antigen receptor (AgR) repertoires from a limited number of AgR genes, using a common mechanism, V(D)J recombination. The AgR loci are among the largest in the genome, and individual genes must overcome huge spatial and temporal challenges to co-localize with optimum variability. Our understanding of the complex mechanisms involved has increased enormously, due in part to new technologies for high resolution mapping of AgR structure and dynamic movement, underpinning mechanisms, and resulting repertoires. This review will examine these advances using the paradigm of the mouse immunoglobulin heavy chain (Igh) locus. We will discuss the key regulatory elements implicated in Igh locus structure. Recent next generation repertoire sequencing methods have shown that local chromatin state at V genes contribute to recombination efficiency. Next on the multidimensional scale, we will describe imaging studies that provided the first picture of the large-scale dynamic looping and contraction the Igh locus undergoes during recombination. We will discuss chromosome conformation capture (3C)-based technologies that have provided higher resolution pictures of Igh locus structure, including the different models that have evolved. We will consider the key transcription factors (PAX5, YY1, E2A, Ikaros), and architectural factors, CTCF and cohesin, that regulate these processes. Lastly, we will discuss a plethora of recent exciting mechanistic findings. These include Rag recombinase scanning for convergent RSS sequences within DNA loops; identification of Igh loop extrusion, and its putative role in Rag scanning; the roles of CTCF, cohesin and cohesin loading factor, WAPL therein; a new phase separation model for Igh locus compartmentalization. We will draw these together and conclude with some horizon-scanning and unresolved questions.
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Affiliation(s)
- Carolyn H Rogers
- Lymphocyte Signalling and Development Programme, Babraham Institute, Cambridge, United Kingdom
| | - Olga Mielczarek
- Nuclear Dynamics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Anne E Corcoran
- Lymphocyte Signalling and Development Programme, Babraham Institute, Cambridge, United Kingdom
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48
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Dai HQ, Hu H, Lou J, Ye AY, Ba Z, Zhang X, Zhang Y, Zhao L, Yoon HS, Chapdelaine-Williams AM, Kyritsis N, Chen H, Johnson K, Lin S, Conte A, Casellas R, Lee CS, Alt FW. Loop extrusion mediates physiological Igh locus contraction for RAG scanning. Nature 2021; 590:338-343. [PMID: 33442057 PMCID: PMC9037962 DOI: 10.1038/s41586-020-03121-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 11/25/2020] [Indexed: 01/29/2023]
Abstract
RAG endonuclease initiates Igh V(D)J recombination in progenitor B cells by binding a JH-recombination signal sequence (RSS) within a recombination centre (RC) and then linearly scanning upstream chromatin, presented by loop extrusion mediated by cohesin, for convergent D-RSSs1,2. The utilization of convergently oriented RSSs and cryptic RSSs is intrinsic to long-range RAG scanning3. Scanning of RAG from the DJH-RC-RSS to upstream convergent VH-RSSs is impeded by D-proximal CTCF-binding elements (CBEs)2-5. Primary progenitor B cells undergo a mechanistically undefined contraction of the VH locus that is proposed to provide distal VHs access to the DJH-RC6-9. Here we report that an inversion of the entire 2.4-Mb VH locus in mouse primary progenitor B cells abrogates rearrangement of both VH-RSSs and normally convergent cryptic RSSs, even though locus contraction still occurs. In addition, this inversion activated both the utilization of cryptic VH-RSSs that are normally in opposite orientation and RAG scanning beyond the VH locus through several convergent CBE domains to the telomere. Together, these findings imply that broad deregulation of CBE impediments in primary progenitor B cells promotes RAG scanning of the VH locus mediated by loop extrusion. We further found that the expression of wings apart-like protein homologue (WAPL)10, a cohesin-unloading factor, was low in primary progenitor B cells compared with v-Abl-transformed progenitor B cell lines that lacked contraction and RAG scanning of the VH locus. Correspondingly, depletion of WAPL in v-Abl-transformed lines activated both processes, further implicating loop extrusion in the locus contraction mechanism.
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Affiliation(s)
- Hai-Qiang Dai
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.,Correspondence: ; ; . Correspondence and requests for materials should be addressed to F.W.A
| | - Hongli Hu
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Jiangman Lou
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Adam Yongxin Ye
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Zhaoqing Ba
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Xuefei Zhang
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Yiwen Zhang
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Lijuan Zhao
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Hye Suk Yoon
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Aimee M. Chapdelaine-Williams
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Nia Kyritsis
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Huan Chen
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Kerstin Johnson
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Sherry Lin
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Andrea Conte
- Lymphocyte Nuclear Biology, NIAMS, NIH, and Center of Cancer Research, NCI, NIH, Bethesda, MD 20892, USA
| | - Rafael Casellas
- Lymphocyte Nuclear Biology, NIAMS, NIH, and Center of Cancer Research, NCI, NIH, Bethesda, MD 20892, USA
| | - Cheng-Sheng Lee
- Institute of Molecular and Cellular Biology, Department of Life Sciences, Hsinchu, Taiwan, 30013, R.O.C.,Correspondence: ; ; . Correspondence and requests for materials should be addressed to F.W.A
| | - Frederick W. Alt
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.,Correspondence: ; ; . Correspondence and requests for materials should be addressed to F.W.A
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49
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Contessoto VG, Cheng RR, Hajitaheri A, Dodero-Rojas E, Mello MF, Lieberman-Aiden E, Wolynes P, Di Pierro M, Onuchic JN. The Nucleome Data Bank: web-based resources to simulate and analyze the three-dimensional genome. Nucleic Acids Res 2021; 49:D172-D182. [PMID: 33021634 PMCID: PMC7778995 DOI: 10.1093/nar/gkaa818] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/05/2020] [Accepted: 10/02/2020] [Indexed: 11/30/2022] Open
Abstract
We introduce the Nucleome Data Bank (NDB), a web-based platform to simulate and analyze the three-dimensional (3D) organization of genomes. The NDB enables physics-based simulation of chromosomal structural dynamics through the MEGABASE + MiChroM computational pipeline. The input of the pipeline consists of epigenetic information sourced from the Encode database; the output consists of the trajectories of chromosomal motions that accurately predict Hi-C and fluorescence insitu hybridization data, as well as multiple observations of chromosomal dynamics in vivo. As an intermediate step, users can also generate chromosomal sub-compartment annotations directly from the same epigenetic input, without the use of any DNA-DNA proximity ligation data. Additionally, the NDB freely hosts both experimental and computational structural genomics data. Besides being able to perform their own genome simulations and download the hosted data, users can also analyze and visualize the same data through custom-designed web-based tools. In particular, the one-dimensional genetic and epigenetic data can be overlaid onto accurate 3D structures of chromosomes, to study the spatial distribution of genetic and epigenetic features. The NDB aims to be a shared resource to biologists, biophysicists and all genome scientists. The NDB is available at https://ndb.rice.edu.
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Affiliation(s)
- Vinícius G Contessoto
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Brazilian Biorenewables National Laboratory-LNBR, Brazilian Center for Research in Energy and Materials-CNPEM, Campinas, SP 13083-100, Brazil
- Department of Physics, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences, São José do Rio Preto, SP 15054-000, Brazil
| | - Ryan R Cheng
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
| | - Arya Hajitaheri
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Department of Computer Science, University of Houston, Houston, TX 77204, USA
| | - Esteban Dodero-Rojas
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Theoretical and Computational Physics Laboratory, University of Costa Rica, San José 5 11501, Costa Rica
| | - Matheus F Mello
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Chemical Engineering Department, Military Institute of Engineering, Rio de Janeiro, RJ 22290-270, Brazil
| | - Erez Lieberman-Aiden
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Peter G Wolynes
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Department of Physics & Astronomy, Rice University, Houston, TX 77005, USA
- Department of Chemistry, Rice University, Houston, TX 77005, USA
- Department of Biosciences, Rice University, Houston, TX 77005, USA
| | - Michele Di Pierro
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - José N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Department of Physics & Astronomy, Rice University, Houston, TX 77005, USA
- Department of Chemistry, Rice University, Houston, TX 77005, USA
- Department of Biosciences, Rice University, Houston, TX 77005, USA
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Ingram SP, Henthorn NT, Warmenhoven JW, Kirkby NF, Mackay RI, Kirkby KJ, Merchant MJ. Hi-C implementation of genome structure for in silico models of radiation-induced DNA damage. PLoS Comput Biol 2020; 16:e1008476. [PMID: 33326415 PMCID: PMC7773326 DOI: 10.1371/journal.pcbi.1008476] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 12/30/2020] [Accepted: 10/28/2020] [Indexed: 02/06/2023] Open
Abstract
Developments in the genome organisation field has resulted in the recent methodology to infer spatial conformations of the genome directly from experimentally measured genome contacts (Hi-C data). This provides a detailed description of both intra- and inter-chromosomal arrangements. Chromosomal intermingling is an important driver for radiation-induced DNA mis-repair. Which is a key biological endpoint of relevance to the fields of cancer therapy (radiotherapy), public health (biodosimetry) and space travel. For the first time, we leverage these methods of inferring genome organisation and couple them to nano-dosimetric radiation track structure modelling to predict quantities and distribution of DNA damage within cell-type specific geometries. These nano-dosimetric simulations are highly dependent on geometry and are benefited from the inclusion of experimentally driven chromosome conformations. We show how the changes in Hi-C contract maps impact the inferred geometries resulting in significant differences in chromosomal intermingling. We demonstrate how these differences propagate through to significant changes in the distribution of DNA damage throughout the cell nucleus, suggesting implications for DNA repair fidelity and subsequent cell fate. We suggest that differences in the geometric clustering for the chromosomes between the cell-types are a plausible factor leading to changes in cellular radiosensitivity. Furthermore, we investigate changes in cell shape, such as flattening, and show that this greatly impacts the distribution of DNA damage. This should be considered when comparing in vitro results to in vivo systems. The effect may be especially important when attempting to translate radiosensitivity measurements at the experimental in vitro level to the patient or human level.
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Affiliation(s)
- Samuel P. Ingram
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Nicholas T. Henthorn
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - John W. Warmenhoven
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Norman F. Kirkby
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Ranald I. Mackay
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Karen J. Kirkby
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Michael J. Merchant
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
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