1
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Bonato A, Chiang M, Corbett D, Kitaev S, Marenduzzo D, Morozov A, Orlandini E. Combinatorics and topological weights of chromatin loop networks. Phys Rev E 2024; 109:064405. [PMID: 39020930 DOI: 10.1103/physreve.109.064405] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 05/15/2024] [Indexed: 07/20/2024]
Abstract
Polymer physics models suggest that chromatin spontaneously folds into loop networks with transcription units (TUs), such as enhancers and promoters, as anchors. Here we use combinatoric arguments to enumerate the emergent chromatin loop networks, both in the case where TUs are labeled and where they are unlabeled. We then combine these mathematical results with those of computer simulations aimed at finding the inter-TU energy required to form a target loop network. We show that different topologies are vastly different in terms of both their combinatorial weight and energy of formation. We explain the latter result qualitatively by computing the topological weight of a given network-i.e., its partition function in statistical mechanics language-in the approximation where excluded volume interactions are neglected. Our results show that networks featuring local loops are statistically more likely with respect to networks including more nonlocal contacts. We suggest our classification of loop networks, together with our estimate of the combinatorial and topological weight of each network, will be relevant to catalog three-dimensional structures of chromatin fibers around eukaryotic genes, and to estimate their relative frequency in both simulations and experiments.
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2
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Keuper K, Bartek J, Maya-Mendoza A. The nexus of nuclear envelope dynamics, circular economy and cancer cell pathophysiology. Eur J Cell Biol 2024; 103:151394. [PMID: 38340500 DOI: 10.1016/j.ejcb.2024.151394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 02/01/2024] [Accepted: 02/02/2024] [Indexed: 02/12/2024] Open
Abstract
The nuclear envelope (NE) is a critical component in maintaining the function and structure of the eukaryotic nucleus. The NE and lamina are disassembled during each cell cycle to enable an open mitosis. Nuclear architecture construction and deconstruction is a prime example of a circular economy, as it fulfills a highly efficient recycling program bound to continuous assessment of the quality and functionality of the building blocks. Alterations in the nuclear dynamics and lamina structure have emerged as important contributors to both oncogenic transformation and cancer progression. However, the knowledge of the NE breakdown and reassembly is still limited to a fraction of participating proteins and complexes. As cancer cells contain highly diverse nuclei in terms of DNA content, but also in terms of nuclear number, size, and shape, it is of great interest to understand the intricate relationship between these nuclear features in cancer cell pathophysiology. In this review, we provide insights into how those NE dynamics are regulated, and how lamina destabilization processes may alter the NE circular economy. Moreover, we expand the knowledge of the lamina-associated domain region by using strategic algorithms, including Artificial Intelligence, to infer protein associations, assess their function and location, and predict cancer-type specificity with implications for the future of cancer diagnosis, prognosis and treatment. Using this approach we identified NUP98 and MECP2 as potential proteins that exhibit upregulation in Acute Myeloid Leukemia (LAML) patients with implications for early diagnosis.
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Affiliation(s)
- Kristina Keuper
- DNA Replication and Cancer Group, Danish Cancer Institute, Copenhagen, Denmark; Genome Integrity Group, Danish Cancer Institute, Copenhagen, Denmark
| | - Jiri Bartek
- Genome Integrity Group, Danish Cancer Institute, Copenhagen, Denmark; Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SciLifeLab, Stockholm, Sweden
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3
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Park J, Kim JJ, Ryu JK. Mechanism of phase condensation for chromosome architecture and function. Exp Mol Med 2024; 56:809-819. [PMID: 38658703 PMCID: PMC11059216 DOI: 10.1038/s12276-024-01226-x] [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: 11/09/2023] [Revised: 02/23/2024] [Accepted: 02/28/2024] [Indexed: 04/26/2024] Open
Abstract
Chromosomal phase separation is involved in a broad spectrum of chromosome organization and functional processes. Nonetheless, the intricacy of this process has left its molecular mechanism unclear. Here, we introduce the principles governing phase separation and its connections to physiological roles in this context. Our primary focus is contrasting two phase separation mechanisms: self-association-induced phase separation (SIPS) and bridging-induced phase separation (BIPS). We provide a comprehensive discussion of the distinct features characterizing these mechanisms and offer illustrative examples that suggest their broad applicability. With a detailed understanding of these mechanisms, we explore their associations with nucleosomes and chromosomal biological functions. This comprehensive review contributes to the exploration of uncharted territory in the intricate interplay between chromosome architecture and function.
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Affiliation(s)
- Jeongveen Park
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Jeong-Jun Kim
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Je-Kyung Ryu
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea.
- Institute of Applied Physics of Seoul National University, Seoul, 08826, South Korea.
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, 08826, South Korea.
- Department of Biological Sciences, Seoul National University, Seoul, 08826, South Korea.
- Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, 08826, South Korea.
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4
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Alagna NS, Thomas TI, Wilson KL, Reddy KL. Choreography of lamina-associated domains: structure meets dynamics. FEBS Lett 2023; 597:2806-2822. [PMID: 37953467 PMCID: PMC10858991 DOI: 10.1002/1873-3468.14771] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/13/2023] [Accepted: 09/17/2023] [Indexed: 11/14/2023]
Abstract
Lamina-associated domains are large regions of heterochromatin positioned at the nuclear periphery. These domains have been implicated in gene repression, especially in the context of development. In mammals, LAD organization is dependent on nuclear lamins, inner nuclear membrane proteins, and chromatin state. In addition, chromatin readers and modifier proteins have been implicated in this organization, potentially serving as molecular tethers that interact with both nuclear envelope proteins and chromatin. More recent studies have focused on teasing apart the rules that govern dynamic LAD organization and how LAD organization, in turn, relates to gene regulation and overall 3D genome organization. This review highlights recent studies in mammalian cells uncovering factors that instruct the choreography of LAD organization, re-organization, and dynamics at the nuclear lamina, including LAD dynamics in interphase and through mitotic exit, when LAD organization is re-established, as well as intra-LAD subdomain variations.
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Affiliation(s)
- Nicholas S. Alagna
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Tiera I. Thomas
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Katherine L. Wilson
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Karen L. Reddy
- Department of Biological Chemistry, Center for Epigenetics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
- Sidney Kimmel Comprehensive Cancer Center, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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5
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Forte G, Buckle A, Boyle S, Marenduzzo D, Gilbert N, Brackley CA. Transcription modulates chromatin dynamics and locus configuration sampling. Nat Struct Mol Biol 2023; 30:1275-1285. [PMID: 37537334 PMCID: PMC10497412 DOI: 10.1038/s41594-023-01059-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 07/07/2023] [Indexed: 08/05/2023]
Abstract
In living cells, the 3D structure of gene loci is dynamic, but this is not revealed by 3C and FISH experiments in fixed samples, leaving a notable gap in our understanding. To overcome these limitations, we applied the highly predictive heteromorphic polymer (HiP-HoP) model to determine chromatin fiber mobility at the Pax6 locus in three mouse cell lines with different transcription states. While transcriptional activity minimally affects movement of 40-kbp regions, we observed that motion of smaller 1-kbp regions depends strongly on local disruption to chromatin fiber structure marked by H3K27 acetylation. This also substantially influenced locus configuration dynamics by modulating protein-mediated promoter-enhancer loops. Importantly, these simulations indicate that chromatin dynamics are sufficiently fast to sample all possible locus conformations within minutes, generating wide dynamic variability within single cells. This combination of simulation and experimental validation provides insight into how transcriptional activity influences chromatin structure and gene dynamics.
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Affiliation(s)
- Giada Forte
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - Adam Buckle
- MRC Human Genetics Unit, Institute of Genetics & Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Shelagh Boyle
- MRC Human Genetics Unit, Institute of Genetics & Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Davide Marenduzzo
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - Nick Gilbert
- MRC Human Genetics Unit, Institute of Genetics & Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK.
| | - Chris A Brackley
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.
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6
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Shaban HA, Gasser SM. Dynamic 3D genome reorganization during senescence: defining cell states through chromatin. Cell Death Differ 2023:10.1038/s41418-023-01197-y. [PMID: 37596440 DOI: 10.1038/s41418-023-01197-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/20/2023] Open
Abstract
Cellular senescence, a cell state characterized by growth arrest and insensitivity to growth stimulatory hormones, is accompanied by a massive change in chromatin organization. Senescence can be induced by a range of physiological signals and pathological stresses and was originally thought to be an irreversible state, implicated in normal development, wound healing, tumor suppression and aging. Recently cellular senescence was shown to be reversible in some cases, with exit being triggered by the modulation of the cell's transcriptional program by the four Yamanaka factors, the suppression of p53 or H3K9me3, PDK1, and/or depletion of AP-1. Coincident with senescence reversal are changes in chromatin organization, most notably the loss of senescence-associated heterochromatin foci (SAHF) found in oncogene-induced senescence. In addition to fixed-cell imaging, chromatin conformation capture and multi-omics have been used to examine chromatin reorganization at different spatial resolutions during senescence. They identify determinants of SAHF formation and other key features that differentiate distinct types of senescence. Not surprisingly, multiple factors, including the time of induction, the type of stress experienced, and the type of cell involved, influence the global reorganization of chromatin in senescence. Here we discuss how changes in the three-dimensional organization of the genome contribute to the regulation of transcription at different stages of senescence. In particular, the distinct contributions of heterochromatin- and lamina-mediated interactions, changes in gene expression, and other cellular control mechanisms are discussed. We propose that high-resolution temporal and spatial analyses of the chromatin landscape during senescence will identify early markers of the different senescence states to help guide clinical diagnosis.
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Affiliation(s)
- Haitham A Shaban
- Precision Oncology Center, Department of Oncology, Lausanne University Hospital, 1005, Lausanne, Switzerland.
- Agora Cancer Research Center Lausanne, Rue du Bugnon 25A, 1005, Lausanne, Switzerland.
- Spectroscopy Department, Institute of Physics Research National Research Centre, Cairo, 33 El-Behouth St., Dokki, Giza, 12311, Egypt.
| | - Susan M Gasser
- Fondation ISREC, Rue du Bugnon 25A, 1005, Lausanne, Switzerland
- Department of Fundamental Microbiology, University of Lausanne, 1015, Lausanne, Switzerland
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Olan I, Handa T, Narita M. Beyond SAHF: An integrative view of chromatin compartmentalization during senescence. Curr Opin Cell Biol 2023; 83:102206. [PMID: 37451177 DOI: 10.1016/j.ceb.2023.102206] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 05/27/2023] [Accepted: 05/30/2023] [Indexed: 07/18/2023]
Abstract
Cellular senescence, a persistent form of cell cycle arrest, has been linked to the formation of heterochromatic foci, accompanied by additional concentric epigenetic layers. However, senescence is a highly heterogeneous phenotype, and the formation of these structures is context dependent. Recent developments in the understanding of the high-order chromatin organization have opened new avenues for contextualizing the nuclear and chromatin phenotypes of senescence. Oncogene-induced senescence displays prominent foci and typically exhibits increased chromatin compartmentalization, based on the chromosome conformation assays, as marked by increased transcompaction and segregation of the heterochromatin and euchromatin. However, other types of senescence (e.g., replicative senescence) exhibit comparatively lower levels of compartmentalization. Thus, a more integrative view of the global rearrangement of the chromatin architecture that occurs during senescence is emerging, with potential functional implications for the heterogeneity of the senescence phenotype.
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Affiliation(s)
- Ioana Olan
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, CB2 0RE, UK.
| | - Tetsuya Handa
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, CB2 0RE, UK
| | - Masashi Narita
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, CB2 0RE, UK.
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8
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Tolokh IS, Kinney NA, Sharakhov IV, Onufriev AV. Strong interactions between highly dynamic lamina-associated domains and the nuclear envelope stabilize the 3D architecture of Drosophila interphase chromatin. Epigenetics Chromatin 2023; 16:21. [PMID: 37254161 PMCID: PMC10228000 DOI: 10.1186/s13072-023-00492-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/04/2023] [Indexed: 06/01/2023] Open
Abstract
BACKGROUND Interactions among topologically associating domains (TADs), and between the nuclear envelope (NE) and lamina-associated domains (LADs) are expected to shape various aspects of three-dimensional (3D) chromatin structure and dynamics; however, relevant genome-wide experiments that may provide statistically significant conclusions remain difficult. RESULTS We have developed a coarse-grained dynamical model of D. melanogaster nuclei at TAD resolution that explicitly accounts for four distinct epigenetic classes of TADs and LAD-NE interactions. The model is parameterized to reproduce the experimental Hi-C map of the wild type (WT) nuclei; it describes time evolution of the chromatin over the G1 phase of the interphase. The simulations include an ensemble of nuclei, corresponding to the experimentally observed set of several possible mutual arrangements of chromosomal arms. The model is validated against multiple structural features of chromatin from several different experiments not used in model development. Predicted positioning of all LADs at the NE is highly dynamic-the same LAD can attach, detach and move far away from the NE multiple times during interphase. The probabilities of LADs to be in contact with the NE vary by an order of magnitude, despite all having the same affinity to the NE in the model. These probabilities are mostly determined by a highly variable local linear density of LADs along the genome, which also has the same strong effect on the predicted positioning of individual TADs -- higher probability of a TAD to be near NE is largely determined by a higher linear density of LADs surrounding this TAD. The distribution of LADs along the chromosome chains plays a notable role in maintaining a non-random average global structure of chromatin. Relatively high affinity of LADs to the NE in the WT nuclei substantially reduces sensitivity of the global radial chromatin distribution to variations in the strength of TAD-TAD interactions compared to the lamin depleted nuclei, where a small (0.5 kT) increase of cross-type TAD-TAD interactions doubles the chromatin density in the central nucleus region. CONCLUSIONS A dynamical model of the entire fruit fly genome makes multiple genome-wide predictions of biological interest. The distribution of LADs along the chromatin chains affects their probabilities to be in contact with the NE and radial positioning of highly mobile TADs, playing a notable role in creating a non-random average global structure of the chromatin. We conjecture that an important role of attractive LAD-NE interactions is to stabilize global chromatin structure against inevitable cell-to-cell variations in TAD-TAD interactions.
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Affiliation(s)
- Igor S. Tolokh
- Department of Computer Science, Virginia Tech, Blacksburg, VA 24061 USA
| | - Nicholas Allen Kinney
- Department of Computer Science, Virginia Tech, Blacksburg, VA 24061 USA
- Department of Entomology, Virginia Tech, Blacksburg, VA 24061 USA
- Edward Via College of Osteopathic Medicine, 2265 Kraft Drive, Blacksburg, VA 24060 USA
| | | | - Alexey V. Onufriev
- Department of Computer Science, Virginia Tech, Blacksburg, VA 24061 USA
- Department of Physics, Virginia Tech, Blacksburg, VA 24061 USA
- Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061 USA
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9
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Bajpai G, Safran S. Mesoscale, long-time mixing of chromosomes and its connection to polymer dynamics. PLoS Comput Biol 2023; 19:e1011142. [PMID: 37228178 DOI: 10.1371/journal.pcbi.1011142] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 05/01/2023] [Indexed: 05/27/2023] Open
Abstract
Chromosomes are arranged in distinct territories within the nucleus of animal cells. Recent experiments have shown that these territories overlap at their edges, suggesting partial mixing during interphase. Experiments that knock-down of condensin II proteins during interphase indicate increased chromosome mixing, which demonstrates control of the mixing. In this study, we use a generic polymer simulation to quantify the dynamics of chromosome mixing over time. We introduce the chromosome mixing index, which quantifies the mixing of distinct chromosomes in the nucleus. We find that the chromosome mixing index in a small confinement volume (as a model of the nucleus), increases as a power-law of the time, with the scaling exponent varying non-monotonically with self-interaction and volume fraction. By comparing the chromosome mixing index with both monomer subdiffusion due to (non-topological) intermingling of chromosomes as well as even slower reptation, we show that for relatively large volume fractions, the scaling exponent of the chromosome mixing index is related to Rouse dynamics for relatively weak chromosome attractions and to reptation for strong attractions. In addition, we extend our model to more realistically account for the situation of the Drosophila chromosome by including the heterogeneity of the polymers and their lengths to account for microphase separation of euchromatin and heterochromatin and their interactions with the nuclear lamina. We find that the interaction with the lamina further impedes chromosome mixing.
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Affiliation(s)
- Gaurav Bajpai
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Samuel Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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10
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Erdel F. Phase transitions in heterochromatin organization. Curr Opin Struct Biol 2023; 80:102597. [PMID: 37087823 DOI: 10.1016/j.sbi.2023.102597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/13/2023] [Accepted: 03/20/2023] [Indexed: 04/25/2023]
Abstract
Heterochromatin formation has been proposed to involve phase transitions on the level of the three-dimensional folding of heterochromatin regions and the liquid-liquid demixing of heterochromatin proteins. Here, I outline the hallmarks of such transitions and the current challenges to detect them in living cells. I further discuss the abundance and properties of prominent heterochromatin proteins and relate them to their potential role in driving phase transitions. Recent data from mouse fibroblasts indicate that pericentric heterochromatin is organized via a reordering transition on the level of heterochromatin regions that does not necessarily involve liquid-liquid demixing of heterochromatin proteins. Evaluating key hallmarks of the different candidate phase transition mechanisms across cell types and species will be needed to complete the current picture.
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Affiliation(s)
- Fabian Erdel
- MCD, Center for Integrative Biology (CBI), CNRS, UPS, Toulouse, France.
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11
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Kamat K, Lao Z, Qi Y, Wang Y, Ma J, Zhang B. Compartmentalization with nuclear landmarks yields random, yet precise, genome organization. Biophys J 2023; 122:1376-1389. [PMID: 36871158 PMCID: PMC10111368 DOI: 10.1016/j.bpj.2023.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 02/19/2023] [Accepted: 03/01/2023] [Indexed: 03/06/2023] Open
Abstract
The 3D organization of eukaryotic genomes plays an important role in genome function. While significant progress has been made in deciphering the folding mechanisms of individual chromosomes, the principles of the dynamic large-scale spatial arrangement of all chromosomes inside the nucleus are poorly understood. We use polymer simulations to model the diploid human genome compartmentalization relative to nuclear bodies such as nuclear lamina, nucleoli, and speckles. We show that a self-organization process based on a cophase separation between chromosomes and nuclear bodies can capture various features of genome organization, including the formation of chromosome territories, phase separation of A/B compartments, and the liquid property of nuclear bodies. The simulated 3D structures quantitatively reproduce both sequencing-based genomic mapping and imaging assays that probe chromatin interaction with nuclear bodies. Importantly, our model captures the heterogeneous distribution of chromosome positioning across cells while simultaneously producing well-defined distances between active chromatin and nuclear speckles. Such heterogeneity and preciseness of genome organization can coexist due to the nonspecificity of phase separation and the slow chromosome dynamics. Together, our work reveals that the cophase separation provides a robust mechanism for us to produce functionally important 3D contacts without requiring thermodynamic equilibration that can be difficult to achieve.
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Affiliation(s)
- Kartik Kamat
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Zhuohan Lao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Yifeng Qi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Yuchuan Wang
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Jian Ma
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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12
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Abdulla AZ, Salari H, Tortora MMC, Vaillant C, Jost D. 4D epigenomics: deciphering the coupling between genome folding and epigenomic regulation with biophysical modeling. Curr Opin Genet Dev 2023; 79:102033. [PMID: 36893485 DOI: 10.1016/j.gde.2023.102033] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/25/2023] [Accepted: 02/20/2023] [Indexed: 03/09/2023]
Abstract
Recent experimental observations suggest a strong coupling between the 3D nuclear chromosome organization and epigenomics. However, the mechanistic and functional bases of such interplay remain elusive. In this review, we describe how biophysical modeling has been instrumental in characterizing how genome folding may impact the formation of epigenomic domains and, conversely, how epigenomic marks may affect chromosome conformation. Finally, we discuss how this mutual feedback loop between chromatin organization and epigenome regulation, via the formation of physicochemical nanoreactors, may represent a key functional role of 3D compartmentalization in the assembly and maintenance of stable - but yet plastic - epigenomic landscapes.
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Affiliation(s)
- Amith Z Abdulla
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69007 Lyon, France; École Normale Supérieure de Lyon, CNRS, Laboratoire de Physique, 46 Allée d'Italie, 69007 Lyon, France. https://twitter.com/@AmithZafal
| | - Hossein Salari
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69007 Lyon, France; École Normale Supérieure de Lyon, CNRS, Laboratoire de Physique, 46 Allée d'Italie, 69007 Lyon, France. https://twitter.com/@hosseinsalari65
| | - Maxime M C Tortora
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69007 Lyon, France
| | - Cédric Vaillant
- École Normale Supérieure de Lyon, CNRS, Laboratoire de Physique, 46 Allée d'Italie, 69007 Lyon, France.
| | - Daniel Jost
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 46 Allée d'Italie, 69007 Lyon, France.
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13
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Shi J, Quevillon MJ, Amorim Valença PH, Whitmer JK. Predicting Adhesive Free Energies of Polymer-Surface Interactions with Machine Learning. ACS APPLIED MATERIALS & INTERFACES 2022; 14:37161-37169. [PMID: 35917495 DOI: 10.1021/acsami.2c08891] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Polymer-surface interactions are crucial to many biological processes and industrial applications. Here we propose a machine learning method to connect a model polymer's sequence with its adhesion to decorated surfaces. We simulate the adhesive free energies of 20000 unique coarse-grained one-dimensional polymer sequences interacting with functionalized surfaces and build support vector regression models that demonstrate inexpensive and reliable prediction of the adhesive free energy as a function of sequence. Our work highlights the promising integration of coarse-grained simulation with data-driven machine learning methods for the design of functional polymers and represents an important step toward linking polymer compositions with polymer-surface interactions.
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Affiliation(s)
- Jiale Shi
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Michael J Quevillon
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Pedro H Amorim Valença
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jonathan K Whitmer
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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14
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Das P, Shen T, McCord RP. Characterizing the variation in chromosome structure ensembles in the context of the nuclear microenvironment. PLoS Comput Biol 2022; 18:e1010392. [PMID: 35969616 PMCID: PMC9410561 DOI: 10.1371/journal.pcbi.1010392] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 08/25/2022] [Accepted: 07/15/2022] [Indexed: 11/23/2022] Open
Abstract
Inside the nucleus, chromosomes are subjected to direct physical interaction between different components, active forces, and thermal noise, leading to the formation of an ensemble of three-dimensional structures. However, it is still not well understood to what extent and how the structural ensemble varies from one chromosome region or cell-type to another. We designed a statistical analysis technique and applied it to single-cell chromosome imaging data to reveal the heterogeneity of individual chromosome structures. By analyzing the resulting structural landscape, we find that the largest dynamic variation is the overall radius of gyration of the chromatin region, followed by domain reorganization within the region. By comparing different human cell-lines and experimental perturbation data using this statistical analysis technique and a network-based similarity quantification approach, we identify both cell-type and condition-specific features of the structural landscapes. We identify a relationship between epigenetic state and the properties of chromosome structure fluctuation and validate this relationship through polymer simulations. Overall, our study suggests that the types of variation in a chromosome structure ensemble are cell-type as well as region-specific and can be attributed to constraints placed on the structure by factors such as variation in epigenetic state. Recent work has revealed principles of how chromosomes are folded and structured inside the human nucleus. It is now even possible to microscopically trace the path of chromosomes in 3D in individual cells. With this data, we can start to examine how much variation exists in chromosome structure and what biological factors may restrict or enhance this variation. Are chromosomes stuck in just a few possible positions or do they move around more freely, sampling many configurations? Here, we use a mathematical approach to compare chromosome structure variation in different cell types, at different locations along the genome, and when key structural proteins are removed. Through these comparisons and dynamic simulations of chromosome behavior, we identify factors that may constrain or promote variation in chromosome structure.
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Affiliation(s)
- Priyojit Das
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Tongye Shen
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee, United States of America
- Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Rachel Patton McCord
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee, United States of America
- Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
- * E-mail:
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15
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Jiang Z, Qi Y, Kamat K, Zhang B. Phase Separation and Correlated Motions in Motorized Genome. J Phys Chem B 2022; 126:5619-5628. [PMID: 35858189 PMCID: PMC9899348 DOI: 10.1021/acs.jpcb.2c03238] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human genome is arranged in the cell nucleus nonrandomly, and phase separation has been proposed as an important driving force for genome organization. However, the cell nucleus is an active system, and the contribution of nonequilibrium activities to phase separation and genome structure and dynamics remains to be explored. We simulated the genome using an energy function parametrized with chromosome conformation capture (Hi-C) data with the presence of active, nondirectional forces that break the detailed balance. We found that active forces that may arise from transcription and chromatin remodeling can dramatically impact the spatial localization of heterochromatin. When applied to euchromatin, active forces can drive heterochromatin to the nuclear envelope and compete with passive interactions among heterochromatin that tend to pull them in opposite directions. Furthermore, active forces induce long-range spatial correlations among genomic loci beyond single chromosome territories. We further showed that the impact of active forces could be understood from the effective temperature defined as the fluctuation-dissipation ratio. Our study suggests that nonequilibrium activities can significantly impact genome structure and dynamics, producing unexpected collective phenomena.
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Affiliation(s)
- Zhongling Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Yifeng Qi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Kartik Kamat
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
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16
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Bellanger A, Madsen-Østerbye J, Galigniana NM, Collas P. Restructuring of Lamina-Associated Domains in Senescence and Cancer. Cells 2022; 11:cells11111846. [PMID: 35681541 PMCID: PMC9180887 DOI: 10.3390/cells11111846] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/02/2022] [Accepted: 06/04/2022] [Indexed: 01/01/2023] Open
Abstract
Induction of cellular senescence or cancer is associated with a reshaping of the nuclear envelope and a broad reorganization of heterochromatin. At the periphery of mammalian nuclei, heterochromatin is stabilized at the nuclear lamina via lamina-associated domains (LADs). Alterations in the composition of the nuclear lamina during senescence lead to a loss of peripheral heterochromatin, repositioning of LADs, and changes in epigenetic states of LADs. Cancer initiation and progression are also accompanied by a massive reprogramming of the epigenome, particularly in domains coinciding with LADs. Here, we review recent knowledge on alterations in chromatin organization and in the epigenome that affect LADs and related genomic domains in senescence and cancer.
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Affiliation(s)
- Aurélie Bellanger
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0372 Oslo, Norway; (A.B.); (J.M.-Ø.); (N.M.G.)
| | - Julia Madsen-Østerbye
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0372 Oslo, Norway; (A.B.); (J.M.-Ø.); (N.M.G.)
| | - Natalia M. Galigniana
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0372 Oslo, Norway; (A.B.); (J.M.-Ø.); (N.M.G.)
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0372 Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0372 Oslo, Norway; (A.B.); (J.M.-Ø.); (N.M.G.)
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0372 Oslo, Norway
- Correspondence:
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17
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Liu Z, Belmonte JCI, Zhang W, Qu J, Liu GH. Deciphering aging at three-dimensional genomic resolution. CELL INSIGHT 2022; 1:100034. [PMID: 37193050 PMCID: PMC10120299 DOI: 10.1016/j.cellin.2022.100034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/19/2022] [Accepted: 05/19/2022] [Indexed: 05/18/2023]
Abstract
Aging is characterized by progressive functional declines at the organismal, organic, and cellular levels and increased susceptibility to aging-related diseases. Epigenetic alteration is a hallmark of aging, senescent cells show epigenomic changes at multiple scales, such as 3D genome reorganization, alterations of histone modifications and chromatin accessibility, and DNA hypomethylation. Chromosome conformation capture (3C)-based technologies have enabled the generation of key information on genomic reorganizations during senescence. A comprehensive understanding of epigenomic alterations during aging will yield important insights into the underlying epigenetic mechanism for aging regulation, the identification of aging-related biomarkers, and the development of potential aging intervention targets.
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Affiliation(s)
- Zunpeng Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | | | - Weiqi Zhang
- University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
- China National Center for Bioinformation, Beijing, 100101, China
| | - Jing Qu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Guang-Hui Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Advanced Innovation Center for Human Brain Protection, and National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China
- Aging Translational Medicine Center, International Center for Aging and Cancer, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China
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18
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Madsen-Østerbye J, Bellanger A, Galigniana NM, Collas P. Biology and Model Predictions of the Dynamics and Heterogeneity of Chromatin-Nuclear Lamina Interactions. Front Cell Dev Biol 2022; 10:913458. [PMID: 35693945 PMCID: PMC9178083 DOI: 10.3389/fcell.2022.913458] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
Associations of chromatin with the nuclear lamina, at the nuclear periphery, help shape the genome in 3 dimensions. The genomic landscape of lamina-associated domains (LADs) is well characterized, but much remains unknown on the physical and mechanistic properties of chromatin conformation at the nuclear lamina. Computational models of chromatin folding at, and interactions with, a surface representing the nuclear lamina are emerging in attempts to characterize these properties and predict chromatin behavior at the lamina in health and disease. Here, we highlight the heterogeneous nature of the nuclear lamina and LADs, outline the main 3-dimensional chromatin structural modeling methods, review applications of modeling chromatin-lamina interactions and discuss biological insights inferred from these models in normal and disease states. Lastly, we address perspectives on future developments in modeling chromatin interactions with the nuclear lamina.
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Affiliation(s)
- Julia Madsen-Østerbye
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Aurélie Bellanger
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Natalia M. Galigniana
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway
- *Correspondence: Philippe Collas,
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19
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Liu Z, Ji Q, Ren J, Yan P, Wu Z, Wang S, Sun L, Wang Z, Li J, Sun G, Liang C, Sun R, Jiang X, Hu J, Ding Y, Wang Q, Bi S, Wei G, Cao G, Zhao G, Wang H, Zhou Q, Belmonte JCI, Qu J, Zhang W, Liu GH. Large-scale chromatin reorganization reactivates placenta-specific genes that drive cellular aging. Dev Cell 2022; 57:1347-1368.e12. [PMID: 35613614 DOI: 10.1016/j.devcel.2022.05.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/24/2022] [Accepted: 05/02/2022] [Indexed: 01/10/2023]
Abstract
Nuclear deformation, a hallmark frequently observed in senescent cells, is presumed to be associated with the erosion of chromatin organization at the nuclear periphery. However, how such gradual changes in higher-order genome organization impinge on local epigenetic modifications to drive cellular mechanisms of aging has remained enigmatic. Here, through large-scale epigenomic analyses of isogenic young, senescent, and progeroid human mesenchymal progenitor cells (hMPCs), we delineate a hierarchy of integrated structural state changes that manifest as heterochromatin loss in repressive compartments, euchromatin weakening in active compartments, switching in interfacing topological compartments, and increasing epigenetic entropy. We found that the epigenetic de-repression unlocks the expression of pregnancy-specific beta-1 glycoprotein (PSG) genes that exacerbate hMPC aging and serve as potential aging biomarkers. Our analyses provide a rich resource for uncovering the principles of epigenomic landscape organization and its changes in cellular aging and for identifying aging drivers and intervention targets with a genome-topology-based mechanism.
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Affiliation(s)
- Zunpeng Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qianzhao Ji
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jie Ren
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pengze Yan
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zeming Wu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Si Wang
- Advanced Innovation Center for Human Brain Protection, National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital, Capital Medical University, Beijing 100053, China; Aging Translational Medicine Center, International Center for Aging and Cancer, Beijing Municipal Geriatric Medical Research Center, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Liang Sun
- NHC Beijing Institute of Geriatrics, NHC Key Laboratory of Geriatrics, Institute of Geriatric Medicine of Chinese Academy of Medical Sciences, National Center of Gerontology/ Beijing Hospital, Beijing 100730, China; Department of Clinical Laboratory, the First Affiliated Hospital of Kunming Medical University, Kunming 650032, China
| | - Zehua Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiaming Li
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guoqiang Sun
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chuqian Liang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Run Sun
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoyu Jiang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jianli Hu
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yingjie Ding
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiaoran Wang
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shijia Bi
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gang Wei
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai 200031, China
| | - Gang Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Bio-Medical Center, Huazhong Agricultural University, Wuhan 430070, China
| | - Guoguang Zhao
- Advanced Innovation Center for Human Brain Protection, National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital, Capital Medical University, Beijing 100053, China; Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Hongmei Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China
| | - Qi Zhou
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China
| | | | - Jing Qu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China.
| | - Weiqi Zhang
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Guang-Hui Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Advanced Innovation Center for Human Brain Protection, National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital, Capital Medical University, Beijing 100053, China; Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China.
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20
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Lamina-associated domains: Tethers and looseners. Curr Opin Cell Biol 2022; 74:80-87. [DOI: 10.1016/j.ceb.2022.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/10/2022] [Accepted: 01/15/2022] [Indexed: 02/07/2023]
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21
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Abstract
The three-dimensional (3D) organization of the genome is shaped by interactions with multiple structures within the nucleus, affecting gene expression outcomes. Technological breakthroughs in recent years have generated vast data reflecting various aspects of nuclear genome architecture in space and time. Integrating these datasets into comprehensive 3D genome models can reveal new insights into genome structure and regulation in normal and disease states. In this chapter, we provide a step-by-step guide on how to generate publication-ready integrated 3D genome models from (raw) Hi-C data and from lamin-genome (LAD) contacts.
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Affiliation(s)
- Jonas Paulsen
- EVOGENE, Department of Biosciences, Faculty of Natural Sciences, University of Oslo, Oslo, Norway.
| | - Philippe Collas
- Department of Molecular Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway
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22
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The Physical Behavior of Interphase Chromosomes: Polymer Theory and Coarse-Grain Computer Simulations. Methods Mol Biol 2022; 2301:235-258. [PMID: 34415539 DOI: 10.1007/978-1-0716-1390-0_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Fluorescence in situ hybridization and chromosome conformation capture methods point to the same conclusion: that chromosomes appear to the external observer as compact structures with a highly nonrandom three-dimensional organization. In this work, we recapitulate the efforts made by us and other groups to rationalize this behavior in terms of the mathematical language and tools of polymer physics. After a brief introduction dedicated to some crucial experiments dissecting the structure of interphase chromosomes, we discuss at a nonspecialistic level some fundamental aspects of theoretical and numerical polymer physics. Then, we inglobe biological and polymer aspects into a polymer model for interphase chromosomes which moves from the observation that mutual topological constraints, such as those typically present between polymer chains in ordinary melts, induce slow chain dynamics and "constraint" chromosomes to resemble double-folded randomly branched polymer conformations. By explicitly turning these ideas into a multi-scale numerical algorithm which is described here in full details, we can design accurate model polymer conformations for interphase chromosomes and offer them for systematic comparison to experiments. The review is concluded by discussing the limitations of our approach and pointing to promising perspectives for future work.
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23
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Chiang M, Brackley CA, Marenduzzo D, Gilbert N. Predicting genome organisation and function with mechanistic modelling. Trends Genet 2021; 38:364-378. [PMID: 34857425 DOI: 10.1016/j.tig.2021.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 10/11/2021] [Accepted: 11/01/2021] [Indexed: 12/14/2022]
Abstract
Fitting-free mechanistic models based on polymer simulations predict chromatin folding in 3D by focussing on the underlying biophysical mechanisms. This class of models has been increasingly used in conjunction with experiments to study the spatial organisation of eukaryotic chromosomes. Feedback from experiments to models leads to successive model refinement and has previously led to the discovery of new principles for genome organisation. Here, we review the basis of mechanistic polymer simulations, explain some of the more recent approaches and the contexts in which they have been useful to explain chromosome biology, and speculate on how they might be used in the future.
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Affiliation(s)
- Michael Chiang
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Chris A Brackley
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Davide Marenduzzo
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Nick Gilbert
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Crewe Road South, Edinburgh, EH4 2XU, UK.
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24
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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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25
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Papantonis A. HMGs as rheostats of chromosomal structure and cell proliferation. Trends Genet 2021; 37:986-994. [PMID: 34311989 DOI: 10.1016/j.tig.2021.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/30/2021] [Accepted: 07/03/2021] [Indexed: 11/18/2022]
Abstract
High mobility group proteins (HMGs) are the most abundant nuclear proteins next to histones and are robustly expressed across tissues and organs. HMGs can uniquely bend or bind distorted DNA, and are central to such processes as transcription, recombination, and DNA repair. However, their dynamic association with chromatin renders capturing HMGs on chromosomes challenging. Recent work has changed this and now implicates these factors in spatial genome organization. Here, I revisit older and review recent literature to describe how HMGs rewire spatial chromatin interactions to sustain homeostasis or promote cellular aging. I propose a 'rheostat' model to explain how HMG-box proteins (HMGBs), and to some extent HMG A proteins (HMGAs), may control cellular aging and, likely, cancer progression.
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Affiliation(s)
- Argyris Papantonis
- Institute of Pathology, University Medical Center Göttingen, 37075 Göttingen, Germany.
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26
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Herman AB, Anerillas C, Harris SC, Munk R, Martindale J, Yang X, Mazan-Mamczarz K, Zhang Y, Heckenbach I, Scheibye-Knudsen M, De S, Sen P, Abdelmohsen K, Gorospe M. Reduction of lamin B receptor levels by miR-340-5p disrupts chromatin, promotes cell senescence and enhances senolysis. Nucleic Acids Res 2021; 49:7389-7405. [PMID: 34181735 PMCID: PMC8287953 DOI: 10.1093/nar/gkab538] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/06/2021] [Accepted: 06/10/2021] [Indexed: 01/10/2023] Open
Abstract
A major stress response influenced by microRNAs (miRNAs) is senescence, a state of indefinite growth arrest triggered by sublethal cell damage. Here, through bioinformatic analysis and experimental validation, we identified miR-340-5p as a novel miRNA that foments cellular senescence. miR-340-5p was highly abundant in diverse senescence models, and miR-340-5p overexpression in proliferating cells rendered them senescent. Among the target mRNAs, miR-340-5p prominently reduced the levels of LBR mRNA, encoding lamin B receptor (LBR). Loss of LBR by ectopic overexpression of miR-340-5p derepressed heterochromatin in lamina-associated domains, promoting the expression of DNA repetitive elements characteristic of senescence. Importantly, overexpressing miR-340-5p enhanced cellular sensitivity to senolytic compounds, while antagonization of miR-340-5p reduced senescent cell markers and engendered resistance to senolytic-induced cell death. We propose that miR-340-5p can be exploited for removing senescent cells to restore tissue homeostasis and mitigate damage by senescent cells in pathologies of human aging.
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Affiliation(s)
- Allison B Herman
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Carlos Anerillas
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Sophia C Harris
- Confocal Imaging Facility, Laboratory of Cardiovascular Sciences, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Rachel Munk
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Jennifer L Martindale
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Xiaoling Yang
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Krystyna Mazan-Mamczarz
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Yongqing Zhang
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Indra J Heckenbach
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, DK-2200, Denmark
| | - Morten Scheibye-Knudsen
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, DK-2200, Denmark
| | - Supriyo De
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Payel Sen
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Kotb Abdelmohsen
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Myriam Gorospe
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
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27
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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: 30] [Impact Index Per Article: 10.0] [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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28
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Zhang X, Liu X, Du Z, Wei L, Fang H, Dong Q, Niu J, Li Y, Gao J, Zhang MQ, Xie W, Wang X. The loss of heterochromatin is associated with multiscale three-dimensional genome reorganization and aberrant transcription during cellular senescence. Genome Res 2021; 31:1121-1135. [PMID: 34140314 PMCID: PMC8256869 DOI: 10.1101/gr.275235.121] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/27/2021] [Indexed: 01/10/2023]
Abstract
Heterochromatin remodeling is critical for various cell processes. In particular, the "loss of heterochromatin" phenotype in cellular senescence is associated with the process of aging and age-related disorders. Although biological processes of senescent cells, including senescence-associated heterochromatin foci (SAHF) formation, chromosome compaction, and redistribution of key proteins, have been closely associated with high-order chromatin structure, the relationship between the high-order chromatin reorganization and the loss of heterochromatin phenotype during senescence has not been fully understood. By using senescent and deep senescent fibroblasts induced by DNA damage harboring the "loss of heterochromatin" phenotype, we observed progressive 3D reorganization of heterochromatin during senescence. Facultative and constitutive heterochromatin marked by H3K27me3 and H3K9me3, respectively, show different alterations. Facultative heterochromatin tends to switch from the repressive B-compartment to the active A-compartment, whereas constitutive heterochromatin shows no significant changes at the compartment level but enhanced interactions between themselves. Both types of heterochromatin show increased chromatin accessibility and gene expression leakage during senescence. Furthermore, increased chromatin accessibility in potential CTCF binding sites accompanies the establishment of novel loops in constitutive heterochromatin. Finally, we also observed aberrant expression of repetitive elements, including LTR (long terminal repeat) and satellite classes. Overall, facultative and constitutive heterochromatin show both similar and distinct multiscale alterations in the 3D map, chromatin accessibility, and gene expression leakage. This study provides an epigenomic map of heterochromatin reorganization during senescence.
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Affiliation(s)
- Xianglin Zhang
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
| | - Xuehui Liu
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
- State Key Laboratory of Medical Molecular Biology, Department of Pathophysiology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
| | - Zhenhai Du
- Center for Stem Cell Biology and Regenerative Medicine, MOE Key Laboratory of Bioinformatics, Tsinghua University, Beijing 100084, China
- THU-PKU Center for Life Sciences, Beijing 100084, China
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lei Wei
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
| | - Huan Fang
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
| | - Qiongye Dong
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
| | - Jing Niu
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Yanda Li
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
| | - Juntao Gao
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
| | - Michael Q Zhang
- Department of Molecular and Cell Biology, Center for Systems Biology, The University of Texas, Richardson, Texas 75080-3021, USA
| | - Wei Xie
- Center for Stem Cell Biology and Regenerative Medicine, MOE Key Laboratory of Bioinformatics, Tsinghua University, Beijing 100084, China
- THU-PKU Center for Life Sciences, Beijing 100084, China
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaowo Wang
- MOE Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; Department of Automation, Tsinghua University, Beijing 100084, China
- Bioinformatics Division, Beijing National Research Center for Information Science and Technology, Beijing 100084, China
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29
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Nichols MH, Corces VG. Principles of 3D compartmentalization of the human genome. Cell Rep 2021; 35:109330. [PMID: 34192544 PMCID: PMC8265014 DOI: 10.1016/j.celrep.2021.109330] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 04/01/2021] [Accepted: 06/09/2021] [Indexed: 11/21/2022] Open
Abstract
Chromatin is organized in the nucleus via CTCF loops and compartmental domains. Here, we compare different cell types to identify distinct paradigms of compartmental domain formation in human tissues. We identify and quantify compartmental forces correlated with histone modifications characteristic of transcriptional activity and previously underappreciated roles for distinct compartmental domains correlated with the presence of H3K27me3 and H3K9me3, respectively. We present a computer simulation model capable of predicting compartmental organization based on the biochemical characteristics of independent chromatin features. Using this model, we show that the underlying forces responsible for compartmental domain formation in human cells are conserved and that the diverse compartmentalization patterns seen across cell types are due to differences in chromatin features. We extend these findings to Drosophila to suggest that the same principles are at work beyond humans. These results offer mechanistic insights into the fundamental forces driving the 3D organization of the genome. Using high-resolution Hi-C data and computer simulations, Nichols and Corces show that compartments arise as a consequence of interactions among proteins that correlate with the presence of H3K27ac, H3K27me3, and H3K9me3, suggesting that human cells contain at least three distinct compartments. The same principles apply to other organisms.
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Affiliation(s)
- Michael H Nichols
- Department of Human Genetics, Emory University School of Medicine, 615 Michael St., Atlanta, GA 30322, USA
| | - Victor G Corces
- Department of Human Genetics, Emory University School of Medicine, 615 Michael St., Atlanta, GA 30322, USA.
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30
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Mehta IS, Riyahi K, Pereira RT, Meaburn KJ, Figgitt M, Kill IR, Eskiw CH, Bridger JM. Interphase Chromosomes in Replicative Senescence: Chromosome Positioning as a Senescence Biomarker and the Lack of Nuclear Motor-Driven Chromosome Repositioning in Senescent Cells. Front Cell Dev Biol 2021; 9:640200. [PMID: 34113611 PMCID: PMC8185894 DOI: 10.3389/fcell.2021.640200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/25/2021] [Indexed: 01/10/2023] Open
Abstract
This study demonstrates, and confirms, that chromosome territory positioning is altered in primary senescent human dermal fibroblasts (HDFs). The chromosome territory positioning pattern is very similar to that found in HDFs made quiescent either by serum starvation or confluence; but not completely. A few chromosomes are found in different locations. One chromosome in particular stands out, chromosome 10, which is located in an intermediate location in young proliferating HDFs, but is found at the nuclear periphery in quiescent cells and in an opposing location of the nuclear interior in senescent HDFs. We have previously demonstrated that individual chromosome territories can be actively and rapidly relocated, with 15 min, after removal of serum from the culture media. These chromosome relocations require nuclear motor activity through the presence of nuclear myosin 1β (NM1β). We now also demonstrate rapid chromosome movement in HDFs after heat-shock at 42°C. Others have shown that heat shock genes are actively relocated using nuclear motor protein activity via actin or NM1β (Khanna et al., 2014; Pradhan et al., 2020). However, this current study reveals, that in senescent HDFs, chromosomes can no longer be relocated to expected nuclear locations upon these two types of stimuli. This coincides with a entirely different organisation and distribution of NM1β within senescent HDFs.
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Affiliation(s)
- Ishita S Mehta
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom.,Tata Institute of Fundamental Research, Mumbai, India
| | - Kumars Riyahi
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Rita Torres Pereira
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Karen J Meaburn
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Martin Figgitt
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom.,Department of Life Sciences, Birmingham City University, Birmingham, United Kingdom
| | - Ian R Kill
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
| | - Christopher H Eskiw
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK, Canada
| | - Joanna M Bridger
- Centre for Genome Engineering and Maintenance, Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Kingston Lane, Brunel University London, Uxbridge, United Kingdom
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31
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Bajpai G, Amiad Pavlov D, Lorber D, Volk T, Safran S. Mesoscale phase separation of chromatin in the nucleus. eLife 2021; 10:e63976. [PMID: 33942717 PMCID: PMC8139833 DOI: 10.7554/elife.63976] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/30/2021] [Indexed: 12/22/2022] Open
Abstract
Intact-organism imaging of Drosophila larvae reveals and quantifies chromatin-aqueous phase separation. The chromatin can be organized near the lamina layer of the nuclear envelope, conventionally fill the nucleus, be organized centrally, or as a wetting droplet. These transitions are controlled by changes in nuclear volume and the interaction of chromatin with the lamina (part of the nuclear envelope) at the nuclear periphery. Using a simple polymeric model that includes the key features of chromatin self-attraction and its binding to the lamina, we demonstrate theoretically that it is the competition of these two effects that determines the mode of chromatin distribution. The qualitative trends as well as the composition profiles obtained in our simulations compare well with the observed intact-organism imaging and quantification. Since the simulations contain only a small number of physical variables we can identify the generic mechanisms underlying the changes in the observed phase separations.
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32
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Rocha A, Dalgarno A, Neretti N. The functional impact of nuclear reorganization in cellular senescence. Brief Funct Genomics 2021; 21:24-34. [PMID: 33755107 PMCID: PMC8789270 DOI: 10.1093/bfgp/elab012] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/12/2021] [Accepted: 02/17/2021] [Indexed: 01/10/2023] Open
Abstract
Cellular senescence is the irreversible cell cycle arrest in response to DNA damage. Because senescent cells accumulate with age and contribute to chronic inflammation, they are promising therapeutic targets for healthspan extension. The senescent phenotype can vary depending on cell type and on the specific insults that induce senescence. This variability is also reflected in the extensive remodeling of the genome organization within the nucleus of senescent cells. Here, we give an overview of the nuclear changes that occur in different forms of senescence, including changes to chromatin state and composition and to the three-dimensional organization of the genome, as well as alterations to the nuclear envelope and to the accessibility of repetitive genomic regions. Many of these changes are shared across all forms of senescence, implicating nuclear organization as a fundamental driver of the senescent state and of how senescent cells interact with the surrounding tissue.
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Affiliation(s)
- Azucena Rocha
- Molecular Biology, Cell Biology and Biochemistry program at Brown University
| | - Audrey Dalgarno
- Molecular Biology, Cell Biology and Biochemistry program at Brown University
| | - Nicola Neretti
- Associate Professor in the Department of Molecular Biology, Cell Biology and Biochemistry at Brown University
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33
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Zhou R, Gao YQ. A DNA Sequence Based Polymer Model for Chromatin Folding. Int J Mol Sci 2021; 22:1328. [PMID: 33572740 PMCID: PMC7865792 DOI: 10.3390/ijms22031328] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/16/2021] [Accepted: 01/25/2021] [Indexed: 11/17/2022] Open
Abstract
The recent development of sequencing technology and imaging methods has provided an unprecedented understanding of the inter-phase chromatin folding in mammalian nuclei. It was found that chromatin folds into topological-associated domains (TADs) of hundreds of kilo base pairs (kbps), and is further divided into spatially segregated compartments (A and B). The compartment B tends to be located near to the periphery or the nuclear center and interacts with other domains of compartments B, while compartment A tends to be located between compartment B and interacts inside the domains. These spatial domains are found to highly correlate with the mosaic CpG island (CGI) density. High CGI density corresponds to compartments A and small TADs, and vice versa. The variation of contact probability as a function of sequential distance roughly follows a power-law decay. Different chromosomes tend to segregate to occupy different chromosome territories. A model that can integrate these properties at multiple length scales and match many aspects is highly desired. Here, we report a DNA-sequence based coarse-grained block copolymer model that considers different interactions between blocks of different CGI density, interactions of TAD formation, as well as interactions between chromatin and the nuclear envelope. This model captures the various single-chromosome properties and partially reproduces the formation of chromosome territories.
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Affiliation(s)
- Rui Zhou
- Biomedical Pioneering Innovation Center, Peking University, Beijing 100871, China;
| | - Yi Qin Gao
- Biomedical Pioneering Innovation Center, Peking University, Beijing 100871, China;
- Beijing Advanced Innovation Center for Genomics, Peking University, Beijing 100871, China
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
- Shenzhen Bay Laboratory, 5F, No.9 Duxue Rd., Nanshan District, Shenzhen 518055, China
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34
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Belokopytova P, Fishman V. Predicting Genome Architecture: Challenges and Solutions. Front Genet 2021; 11:617202. [PMID: 33552135 PMCID: PMC7862721 DOI: 10.3389/fgene.2020.617202] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/15/2020] [Indexed: 12/22/2022] Open
Abstract
Genome architecture plays a pivotal role in gene regulation. The use of high-throughput methods for chromatin profiling and 3-D interaction mapping provide rich experimental data sets describing genome organization and dynamics. These data challenge development of new models and algorithms connecting genome architecture with epigenetic marks. In this review, we describe how chromatin architecture could be reconstructed from epigenetic data using biophysical or statistical approaches. We discuss the applicability and limitations of these methods for understanding the mechanisms of chromatin organization. We also highlight the emergence of new predictive approaches for scoring effects of structural variations in human cells.
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Affiliation(s)
- Polina Belokopytova
- Natural Sciences Department, Novosibirsk State University, Novosibirsk, Russia
- Institute of Cytology and Genetics Siberian Branch of Russian Academy of Sciences (SB RAS), Novosibirsk, Russia
| | - Veniamin Fishman
- Natural Sciences Department, Novosibirsk State University, Novosibirsk, Russia
- Institute of Cytology and Genetics Siberian Branch of Russian Academy of Sciences (SB RAS), Novosibirsk, Russia
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35
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Brunet A, Destainville N, Collas P. Physical constraints in polymer modeling of chromatin associations with the nuclear periphery at kilobase scale. Nucleus 2021; 12:6-20. [PMID: 33435761 PMCID: PMC7808377 DOI: 10.1080/19491034.2020.1868105] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Interactions of chromatin with the nuclear lamina imposes a radial genome distribution important for nuclear functions. How physical properties of chromatin affect these interactions is unclear. We used polymer simulations to model how physical parameters of chromatin affect its interaction with the lamina. Impact of polymer stiffness is greater than stretching on its configurations at the lamina; these are manifested as trains describing extended interactions, and loops describing desorbed regions . Conferring an attraction potential leads to persistent interaction and adsorption-desorption regimes manifested by fluctuations between trains and loops. These are modulated by polymer stiffness and stretching, with a dominant impact of stiffness on resulting structural configurations. We infer that flexible euchromatin is more prone to stochastic interactions with lamins than rigid heterochromatin characterizing constitutive LADs. Our models provide insights on the physical properties of chromatin as a polymer which affect the dynamics and patterns of interactions with the nuclear lamina.
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Affiliation(s)
- Annaël Brunet
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo , Oslo, Norway
| | - Nicolas Destainville
- Laboratoire De Physique Théorique, IRSAMC, Université De Toulouse (UPS) , CNRS, Toulouse, France
| | - Philippe Collas
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo , Oslo, Norway.,Department of Immunology and Transfusion Medicine, Oslo University Hospital , Oslo, Norway
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36
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Strickfaden H. Reflections on the organization and the physical state of chromatin in eukaryotic cells. Genome 2020; 64:311-325. [PMID: 33306433 DOI: 10.1139/gen-2020-0132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In recent years, our perception of chromatin structure and organization in the cell nucleus has changed in fundamental ways. The 30 nm chromatin fiber has lost its status as an essential in vivo structure. Hi-C and related biochemical methods, advanced electron and super-resolved fluorescence microscopy, together with concepts from soft matter physics, have revolutionized the field. A comprehensive understanding of the structural and functional interactions that regulate cell cycle and cell type specific nuclear functions appears within reach, but it requires the integration of top-down and bottom-up approachs. In this review, I present an update on nuclear architecture studies with an emphasis on organization and the controversy regarding the physical state of chromatin in cells.
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Affiliation(s)
- Hilmar Strickfaden
- Departments of Cell Biology and Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Departments of Cell Biology and Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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37
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Penagos-Puig A, Furlan-Magaril M. Heterochromatin as an Important Driver of Genome Organization. Front Cell Dev Biol 2020; 8:579137. [PMID: 33072761 PMCID: PMC7530337 DOI: 10.3389/fcell.2020.579137] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/31/2020] [Indexed: 12/14/2022] Open
Abstract
Heterochromatin is a constituent of eukaryotic genomes with functions spanning from gene expression silencing to constraining DNA replication and repair. Inside the nucleus, heterochromatin segregates spatially from euchromatin and is localized preferentially toward the nuclear periphery and surrounding the nucleolus. Despite being an abundant nuclear compartment, little is known about how heterochromatin regulates and participates in the mechanisms driving genome organization. Here, we review pioneer and recent evidence that explores the functional role of heterochromatin in the formation of distinct chromatin compartments and how failure of the molecular mechanisms forming heterochromatin leads to disarray of genome conformation and disease.
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Affiliation(s)
- Andrés Penagos-Puig
- Department of Molecular Genetics, Institute of Cellular Physiology, National Autonomous University of Mexico, Mexico City, Mexico
| | - Mayra Furlan-Magaril
- Department of Molecular Genetics, Institute of Cellular Physiology, National Autonomous University of Mexico, Mexico City, Mexico
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38
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Mizi A, Zhang S, Papantonis A. Genome folding and refolding in differentiation and cellular senescence. Curr Opin Cell Biol 2020; 67:56-63. [PMID: 32911122 DOI: 10.1016/j.ceb.2020.08.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/02/2020] [Accepted: 08/03/2020] [Indexed: 12/11/2022]
Abstract
The spatial conformation of chromatin within the confines of eukaryotic cell nuclei is now acknowledged as a decisive epigenetic mechanism for the modulation of such cellular functions as gene expression regulation, DNA replication or DNA damage repair. Of course, these processes are tightly regulated during organismal development and markedly affected by cellular ageing. Thus, the question that arises is to what extent does folding or refolding of the genome in three-dimensional space underlie the progression of development or ageing? Herein, we discuss recent experimental and modelling evidence to address this question and revisit how these seemingly different processed might represent two sides of the same coin.
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Affiliation(s)
- Athanasia Mizi
- Institute of Pathology, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Shu Zhang
- Institute of Pathology, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Argyris Papantonis
- Institute of Pathology, University Medical Center Göttingen, 37075, Göttingen, Germany.
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39
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Liu M, Lu Y, Yang B, Chen Y, Radda JSD, Hu M, Katz SG, Wang S. Multiplexed imaging of nucleome architectures in single cells of mammalian tissue. Nat Commun 2020; 11:2907. [PMID: 32518300 PMCID: PMC7283333 DOI: 10.1038/s41467-020-16732-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 05/19/2020] [Indexed: 01/13/2023] Open
Abstract
The three-dimensional architecture of the genome affects genomic functions. Multiple genome architectures at different length scales, including chromatin loops, domains, compartments, and lamina- and nucleolus-associated regions, have been discovered. However, how these structures are arranged in the same cell and how they are mutually correlated in different cell types in mammalian tissue are largely unknown. Here, we develop Multiplexed Imaging of Nucleome Architectures that measures multiscale chromatin folding, copy numbers of numerous RNA species, and associations of numerous genomic regions with nuclear lamina, nucleoli and surface of chromosomes in the same, single cells. We apply this method in mouse fetal liver, and identify de novo cell-type-specific chromatin architectures associated with gene expression, as well as cell-type-independent principles of chromatin organization. Polymer simulation shows that both intra-chromosomal self-associating interactions and extra-chromosomal interactions are necessary to establish the observed organization. Our results illustrate a multi-faceted picture and physical principles of chromatin organization. The three-dimensional architecture of the genome affects genomic functions. Here, the authors developed Multiplexed Imaging of Nucleome Architectures to measure multiscale chromatin folding, RNA profiles, and associations of numerous genomic regions with nuclear lamina and nucleoli in the same, single cells in heterogeneous tissue.
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Affiliation(s)
- Miao Liu
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA
| | - Yanfang Lu
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA
| | - Bing Yang
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA
| | - Yanbo Chen
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA
| | - Jonathan S D Radda
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA
| | - Mengwei Hu
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA
| | - Samuel G Katz
- Department of Pathology, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA
| | - Siyuan Wang
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA. .,Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT, 06510, USA.
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40
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Brackey CA, Marenduzzo D, Gilbert N. Mechanistic modeling of chromatin folding to understand function. Nat Methods 2020; 17:767-775. [PMID: 32514111 DOI: 10.1038/s41592-020-0852-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 04/29/2020] [Indexed: 01/06/2023]
Abstract
Experimental approaches have been applied to address questions in understanding three-dimensional chromatin organization and function. As datasets increase in size and complexity, it becomes a challenge to reach a mechanistic interpretation of experimental results. Polymer simulations and mechanistic modeling have been applied to explain experimental observations and their links to different aspects of genome function. Here we provide a guide for biologists, explaining different simulation approaches and the contexts in which they have been used.
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Affiliation(s)
- Chris A Brackey
- SUPA School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - Davide Marenduzzo
- SUPA School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.
| | - Nick Gilbert
- MRC Human Genetics Unit, Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, UK.
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Maji A, Ahmed JA, Roy S, Chakrabarti B, Mitra MK. A Lamin-Associated Chromatin Model for Chromosome Organization. Biophys J 2020; 118:3041-3050. [PMID: 32492372 DOI: 10.1016/j.bpj.2020.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/09/2020] [Accepted: 05/12/2020] [Indexed: 12/22/2022] Open
Abstract
We propose a simple model for chromatin organization based on the interaction of the chromatin fibers with lamin proteins along the nuclear membrane. Lamin proteins are known to be a major factor that influences chromatin organization and hence gene expression in the cells. We provide a quantitative understanding of lamin-associated chromatin organization in a crowded macromolecular environment by systematically varying the heteropolymer segment distribution and the strength of the lamin-chromatin attractive interaction. Our minimal polymer model reproduces the formation of lamin-associated-domains and provides an in silico tool for quantifying domain length distributions for different distributions of heteropolymer segments. We show that a Gaussian distribution of heteropolymer segments, coupled with strong lamin-chromatin interactions, can qualitatively reproduce observed length distributions of lamin-associated-domains. Further, lamin-mediated interaction can enhance the formation of chromosome territories as well as the organization of chromatin into tightly packed heterochromatin and the loosely packed gene-rich euchromatin regions.
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Affiliation(s)
- Ajoy Maji
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India
| | - Jahir A Ahmed
- AKI's Poona College of Arts, Science and Commerce, Camp, Pune, India
| | - Subhankar Roy
- Saha Institute of Nuclear Physics, HBNI, Kolkata, India
| | | | - Mithun K Mitra
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India.
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Abstract
At the nuclear periphery, associations of chromatin with the nuclear lamina through lamina-associated domains (LADs) aid functional organization of the genome. We review the organization of LADs and provide evidence of LAD heterogeneity from cell ensemble and single-cell data. LADs are typically repressive environments in the genome; nonetheless, we discuss findings of lamin interactions with regulatory elements of active genes, and the role lamins may play in genome regulation. We address the relationship between LADs and other genome organizers, and the involvement of LADs in laminopathies. The current data lay the basis for future studies on the significance of lamin-chromatin interactions in health and disease.
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Affiliation(s)
- Nolwenn Briand
- Department of Molecular Medicine, Faculty of Medicine, University of Oslo, PO Box 1112 Blindern, 0317, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0424, Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Faculty of Medicine, University of Oslo, PO Box 1112 Blindern, 0317, Oslo, Norway.
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0424, Oslo, Norway.
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4D Genome Rewiring during Oncogene-Induced and Replicative Senescence. Mol Cell 2020; 78:522-538.e9. [PMID: 32220303 PMCID: PMC7208559 DOI: 10.1016/j.molcel.2020.03.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 12/20/2019] [Accepted: 03/04/2020] [Indexed: 12/26/2022]
Abstract
To understand the role of the extensive senescence-associated 3D genome reorganization, we generated genome-wide chromatin interaction maps, epigenome, replication-timing, whole-genome bisulfite sequencing, and gene expression profiles from cells entering replicative senescence (RS) or upon oncogene-induced senescence (OIS). We identify senescence-associated heterochromatin domains (SAHDs). Differential intra- versus inter-SAHD interactions lead to the formation of senescence-associated heterochromatin foci (SAHFs) in OIS but not in RS. This OIS-specific configuration brings active genes located in genomic regions adjacent to SAHDs in close spatial proximity and favors their expression. We also identify DNMT1 as a factor that induces SAHFs by promoting HMGA2 expression. Upon DNMT1 depletion, OIS cells transition to a 3D genome conformation akin to that of cells in replicative senescence. These data show how multi-omics and imaging can identify critical features of RS and OIS and discover determinants of acute senescence and SAHF formation. Deep multi-omics characterization of replicative and oncogene-induced senescence Senescence-associated heterochromatin domains (SAHDs) form SAHFs via 3D changes DNMT1 is required for SAHF formation via regulation of HMGA2 expression SAHF formation leads to expression of SAHF-adjacent genes via 3D chromatin contacts
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Abstract
Chromosome organisation is increasingly recognised as an essential component of genome regulation, cell fate and cell health. Within the realm of transposable elements (TEs) however, the spatial information of how genomes are folded is still only rarely integrated in experimental studies or accounted for in modelling. Whilst polymer physics is recognised as an important tool to understand the mechanisms of genome folding, in this commentary we discuss its potential applicability to aspects of TE biology. Based on recent works on the relationship between genome organisation and TE integration, we argue that existing polymer models may be extended to create a predictive framework for the study of TE integration patterns. We suggest that these models may offer orthogonal and generic insights into the integration profiles (or "topography") of TEs across organisms. In addition, we provide simple polymer physics arguments and preliminary molecular dynamics simulations of TEs inserting into heterogeneously flexible polymers. By considering this simple model, we show how polymer folding and local flexibility may generically affect TE integration patterns. The preliminary discussion reported in this commentary is aimed to lay the foundations for a large-scale analysis of TE integration dynamics and topography as a function of the three-dimensional host genome.
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Zhou R, Gao YQ. Polymer models for the mechanisms of chromatin 3D folding: review and perspective. Phys Chem Chem Phys 2020; 22:20189-20201. [DOI: 10.1039/d0cp01877e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this perspective paper, classical physical models for mammalian interphase chromatin folding are reviewed.
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Affiliation(s)
- Rui Zhou
- Biomedical Pioneering Innovation Center
- Peking University
- 100871 Beijing
- China
| | - Yi Qin Gao
- Biomedical Pioneering Innovation Center
- Peking University
- 100871 Beijing
- China
- Beijing Advanced Innovation Center for Genomics
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Michieletto D, Colì D, Marenduzzo D, Orlandini E. Nonequilibrium Theory of Epigenomic Microphase Separation in the Cell Nucleus. PHYSICAL REVIEW LETTERS 2019; 123:228101. [PMID: 31868408 DOI: 10.1103/physrevlett.123.228101] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/05/2019] [Indexed: 06/10/2023]
Abstract
Understanding the spatial organization of the genome in the cell nucleus is one of the current grand challenges in biophysics. Certain biochemical-or epigenetic-marks that are deposited along the genome are thought to play an important, yet poorly understood, role in determining genome organization and cell identity. The physical principles underlying the interplay between epigenetic dynamics and genome folding remain elusive. Here we propose and study a theory that assumes a coupling between epigenetic mark and genome densities, and which can be applied at the scale of the whole nucleus. We show that equilibrium models are not compatible with experiments and a qualitative agreement is recovered by accounting for nonequilibrium processes that can stabilize microphase separated epigenomic domains. We finally discuss the potential biophysical origin of these terms.
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Affiliation(s)
- Davide Michieletto
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
- Centre for Mathematical Biology, and Department of Mathematical Sciences, University of Bath, North Rd, Bath BA2 7AY, United Kingdom
| | - Davide Colì
- Dipartimento di Fisica e Astronomia and Sezione INFN, Università degli Studi di Padova, I-35131 Padova, Italy
| | - Davide Marenduzzo
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - Enzo Orlandini
- Dipartimento di Fisica e Astronomia and Sezione INFN, Università degli Studi di Padova, I-35131 Padova, Italy
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