1
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Manivannan V, Inamdar MM, Padinhateeri R. Role of diffusion and reaction of the constituents in spreading of histone modification marks. PLoS Comput Biol 2024; 20:e1012235. [PMID: 38991050 DOI: 10.1371/journal.pcbi.1012235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 06/06/2024] [Indexed: 07/13/2024] Open
Abstract
Cells switch genes ON or OFF by altering the state of chromatin via histone modifications at specific regulatory locations along the chromatin polymer. These gene regulation processes are carried out by a network of reactions in which the histone marks spread to neighboring regions with the help of enzymes. In the literature, this spreading has been studied as a purely kinetic, non-diffusive process considering the interactions between neighboring nucleosomes. In this work, we go beyond this framework and study the spreading of modifications using a reaction-diffusion (RD) model accounting for the diffusion of the constituents. We quantitatively segregate the modification profiles generated from kinetic and RD models. The diffusion and degradation of enzymes set a natural length scale for limiting the domain size of modification spreading, and the resulting enzyme limitation is inherent in our model. We also demonstrate the emergence of confined modification domains without the explicit requirement of a nucleation site. We explore polymer compaction effects on spreading and show that single-cell domains may differ from averaged profiles. We find that the modification profiles from our model are comparable with existing H3K9me3 data of S. pombe.
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Affiliation(s)
- Vinoth Manivannan
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Mandar M Inamdar
- Department of Civil Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
- Sunita Sanghi Centre of Aging and Neurodegenerative Diseases, Indian Institute of Technology Bombay, Mumbai, India
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2
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Sahoo S, Kadam S, Padinhateeri R, Kumar PBS. Nonequilibrium switching of segmental states can influence compaction of chromatin. SOFT MATTER 2024; 20:4621-4632. [PMID: 38819321 DOI: 10.1039/d4sm00274a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Knowledge about the dynamic nature of chromatin organization is essential to understand the regulation of processes like DNA transcription and repair. The existing models of chromatin assume that protein organization and chemical states along chromatin are static and the 3D organization is purely a result of protein-mediated intra-chromatin interactions. Here we present a new hypothesis that certain nonequilibrium processes, such as switching of chemical and physical states due to nucleosome assembly/disassembly or gene repression/activation, can also simultaneously influence chromatin configurations. To understand the implications of this inherent nonequilibrium switching, we present a block copolymer model of chromatin, with switching of its segmental states between two states, mimicking active/repressed or protein unbound/bound states. We show that competition between switching timescale Tt, polymer relaxation timescale τp, and segmental relaxation timescale τs can lead to non-trivial changes in chromatin organization, leading to changes in local compaction and contact probabilities. As a function of the switching timescale, the radius of gyration of chromatin shows a non-monotonic behavior with a prominent minimum when Tt ≈ τp and a maximum when Tt ≈ τs. We find that polymers with a small segment length exhibit a more compact structure than those with larger segment lengths. We also find that the switching can lead to higher contact probability and better mixing of far-away segments. Our study also shows that the nature of the distribution of chromatin clusters varies widely as we change the switching rate.
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Affiliation(s)
- Soudamini Sahoo
- Department of Physics, Indian Institute of Technology Palakkad, Palakkad, 678623, India
- Department of Physics and Astronomy, National Institute of Technology Rourkela, Rourkela, 769008, India
| | - Sangram Kadam
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
| | - P B Sunil Kumar
- Department of Physics, Indian Institute of Technology Palakkad, Palakkad, 678623, India
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
- Center for Soft and Biological Matter, Indian Institute of Technology Madras, Chennai, 600036, India
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3
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Kant A, Guo Z, Vinayak V, Neguembor MV, Li WS, Agrawal V, Pujadas E, Almassalha L, Backman V, Lakadamyali M, Cosma MP, Shenoy VB. Active transcription and epigenetic reactions synergistically regulate meso-scale genomic organization. Nat Commun 2024; 15:4338. [PMID: 38773126 PMCID: PMC11109243 DOI: 10.1038/s41467-024-48698-z] [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: 04/24/2023] [Accepted: 05/06/2024] [Indexed: 05/23/2024] Open
Abstract
In interphase nuclei, chromatin forms dense domains of characteristic sizes, but the influence of transcription and histone modifications on domain size is not understood. We present a theoretical model exploring this relationship, considering chromatin-chromatin interactions, histone modifications, and chromatin extrusion. We predict that the size of heterochromatic domains is governed by a balance among the diffusive flux of methylated histones sustaining them and the acetylation reactions in the domains and the process of loop extrusion via supercoiling by RNAPII at their periphery, which contributes to size reduction. Super-resolution and nano-imaging of five distinct cell lines confirm the predictions indicating that the absence of transcription leads to larger heterochromatin domains. Furthermore, the model accurately reproduces the findings regarding how transcription-mediated supercoiling loss can mitigate the impacts of excessive cohesin loading. Our findings shed light on the role of transcription in genome organization, offering insights into chromatin dynamics and potential therapeutic targets.
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Affiliation(s)
- Aayush Kant
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Zixian Guo
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Vinayak Vinayak
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Maria Victoria Neguembor
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003, Barcelona, Spain
| | - Wing Shun Li
- Department of Applied Physics, Northwestern University, Evanston, IL, 60208, USA
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, IL, 60202, USA
| | - Vasundhara Agrawal
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, IL, 60202, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Emily Pujadas
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, IL, 60202, USA
| | - Luay Almassalha
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, IL, 60202, USA
- Department of Gastroenterology and Hepatology, Northwestern Memorial Hospital, Chicago, IL, 60611, USA
| | - Vadim Backman
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, IL, 60202, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Melike Lakadamyali
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Maria Pia Cosma
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003, Barcelona, Spain
- ICREA, Barcelona, 08010, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, 08003, Spain
| | - Vivek B Shenoy
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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4
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Sood A, Schuette G, Zhang B. Dynamical phase transition in models that couple chromatin folding with histone modifications. Phys Rev E 2024; 109:054411. [PMID: 38907407 DOI: 10.1103/physreve.109.054411] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 04/25/2024] [Indexed: 06/24/2024]
Abstract
Genomic regions can acquire heritable epigenetic states through unique histone modifications, which lead to stable gene expression patterns without altering the underlying DNA sequence. However, the relationship between chromatin conformational dynamics and epigenetic stability is poorly understood. In this paper, we propose kinetic models to investigate the dynamic fluctuations of histone modifications and the spatial interactions between nucleosomes. Our model explicitly incorporates the influence of chemical modifications on the structural stability of chromatin and the contribution of chromatin contacts to the cooperative nature of chemical reactions. Through stochastic simulations and analytical theory, we have discovered distinct steady-state outcomes in different kinetic regimes, resembling a dynamical phase transition. Importantly, we have validated that the emergence of this transition, which occurs on biologically relevant timescales, is robust against variations in model design and parameters. Our findings suggest that the viscoelastic properties of chromatin and the timescale at which it transitions from a gel-like to a liquidlike state significantly impact dynamic processes that occur along the one-dimensional DNA sequence.
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Movilla Miangolarra A, Saxton DS, Yan Z, Rine J, Howard M. Two-way feedback between chromatin compaction and histone modification state explains Saccharomyces cerevisiae heterochromatin bistability. Proc Natl Acad Sci U S A 2024; 121:e2403316121. [PMID: 38593082 PMCID: PMC11032488 DOI: 10.1073/pnas.2403316121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 03/02/2024] [Indexed: 04/11/2024] Open
Abstract
Compact chromatin is closely linked with gene silencing in part by sterically masking access to promoters, inhibiting transcription factor binding and preventing polymerase from efficiently transcribing a gene. However, a broader hypothesis suggests that chromatin compaction can be both a cause and a consequence of the locus histone modification state, with a tight bidirectional interaction underpinning bistable transcriptional states. To rigorously test this hypothesis, we developed a mathematical model for the dynamics of the HMR locus in Saccharomyces cerevisiae, that incorporates activating histone modifications, silencing proteins, and a dynamic, acetylation-dependent, three-dimensional locus size. Chromatin compaction enhances silencer protein binding, which in turn feeds back to remove activating histone modifications, leading to further compaction. The bistable output of the model was in good agreement with prior quantitative data, including switching rates from expressed to silent states (and vice versa), and protein binding/histone modification levels within the locus. We then tested the model by predicting changes in switching rates as the genetic length of the locus was increased, which were then experimentally verified. Such bidirectional feedback between chromatin compaction and the histone modification state may be a widespread and important regulatory mechanism given the hallmarks of many heterochromatic regions: physical chromatin compaction and dimerizing (or multivalent) silencing proteins.
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Affiliation(s)
| | - Daniel S. Saxton
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Zhi Yan
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Jasper Rine
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Martin Howard
- Department of Computational and Systems Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
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6
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Murphy SE, Boettiger AN. Polycomb repression of Hox genes involves spatial feedback but not domain compaction or phase transition. Nat Genet 2024; 56:493-504. [PMID: 38361032 DOI: 10.1038/s41588-024-01661-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 01/10/2024] [Indexed: 02/17/2024]
Abstract
Polycomb group proteins have a critical role in silencing transcription during development. It is commonly proposed that Polycomb-dependent changes in genome folding, which compact chromatin, contribute directly to repression by blocking the binding of activating complexes. Recently, it has also been argued that liquid-liquid demixing of Polycomb proteins facilitates this compaction and repression by phase-separating target genes into a membraneless compartment. To test these models, we used Optical Reconstruction of Chromatin Architecture to trace the Hoxa gene cluster, a canonical Polycomb target, in thousands of single cells. Across multiple cell types, we find that Polycomb-bound chromatin frequently explores decompact states and partial mixing with neighboring chromatin, while remaining uniformly repressed, challenging the repression-by-compaction or phase-separation models. Using polymer simulations, we show that these observed flexible ensembles can be explained by 'spatial feedback'-transient contacts that contribute to the propagation of the epigenetic state (epigenetic memory), without inducing a globular organization.
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Affiliation(s)
- Sedona Eve Murphy
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
- Department of Cell Biology, Yale University, New Haven, CT, USA
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7
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Nakanishi R, Hukushima K. Emergence of compact disordered phase in a polymer Potts model. Phys Rev E 2024; 109:014405. [PMID: 38366473 DOI: 10.1103/physreve.109.014405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 01/02/2024] [Indexed: 02/18/2024]
Abstract
One of the central problems in epigenetics is how epigenetic modification patterns and chromatin structure are regulated in the cell nucleus. The polymer Potts model, a recently studied model of chromatins, is introduced with an offset in the interaction energy as a parameter, and the equilibrium properties are investigated using the mean-field analysis of the lattice model and molecular dynamics simulations of the off-lattice model. The results show that in common with both models, a phase emerges, which could be called the compact-disordered phase, in which the polymer conformation is compact and the epigenetic modification pattern is disordered, depending on the offset in the interaction energy and the fraction of the modified nucleosomes.
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Affiliation(s)
- Ryo Nakanishi
- Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Koji Hukushima
- Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
- Komaba Institute for Science, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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8
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Owen JA, Osmanović D, Mirny L. Design principles of 3D epigenetic memory systems. Science 2023; 382:eadg3053. [PMID: 37972190 PMCID: PMC11075759 DOI: 10.1126/science.adg3053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 09/28/2023] [Indexed: 11/19/2023]
Abstract
Cells remember their identities, in part, by using epigenetic marks-chemical modifications placed along the genome. How can mark patterns remain stable over cell generations despite their constant erosion by replication and other processes? We developed a theoretical model that reveals that three-dimensional (3D) genome organization can stabilize epigenetic memory as long as (i) there is a large density difference between chromatin compartments, (ii) modifying "reader-writer" enzymes spread marks in three dimensions, and (iii) the enzymes are limited in abundance relative to their histone substrates. Analogous to an associative memory that encodes memory in neuronal connectivity, mark patterns are encoded in a 3D network of chromosomal contacts. Our model provides a unified account of diverse observations and reveals a key role of 3D genome organization in epigenetic memory.
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Affiliation(s)
- Jeremy A. Owen
- Department of Physics, Massachusetts Institute of Technology; Cambridge, USA
| | - Dino Osmanović
- Department of Mechanical and Aeronautical Engineering, UCLA; Los Angeles, USA
| | - Leonid Mirny
- Department of Physics, Massachusetts Institute of Technology; Cambridge, USA
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9
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Hamali B, Amine AAA, Al-Sady B. Regulation of the heterochromatin spreading reaction by trans-acting factors. Open Biol 2023; 13:230271. [PMID: 37935357 PMCID: PMC10645111 DOI: 10.1098/rsob.230271] [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: 08/10/2023] [Accepted: 10/03/2023] [Indexed: 11/09/2023] Open
Abstract
Heterochromatin is a gene-repressive protein-nucleic acid ultrastructure that is initially nucleated by DNA sequences. However, following nucleation, heterochromatin can then propagate along the chromatin template in a sequence-independent manner in a reaction termed spreading. At the heart of this process are enzymes that deposit chemical information on chromatin, which attracts the factors that execute chromatin compaction and transcriptional or co/post-transcriptional gene silencing. Given that these enzymes deposit guiding chemical information on chromatin they are commonly termed 'writers'. While the processes of nucleation and central actions of writers have been extensively studied and reviewed, less is understood about how the spreading process is regulated. We discuss how the chromatin substrate is prepared for heterochromatic spreading, and how trans-acting factors beyond writer enzymes regulate it. We examine mechanisms by which trans-acting factors in Suv39, PRC2, SETDB1 and SIR writer systems regulate spreading of the respective heterochromatic marks across chromatin. While these systems are in some cases evolutionarily and mechanistically quite distant, common mechanisms emerge which these trans-acting factors exploit to tune the spreading reaction.
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Affiliation(s)
- Bulut Hamali
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143, USA
- The G. W. Hooper Foundation, San Francisco, CA 94143, USA
- College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Ahmed A A Amine
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143, USA
- The G. W. Hooper Foundation, San Francisco, CA 94143, USA
| | - Bassem Al-Sady
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143, USA
- The G. W. Hooper Foundation, San Francisco, CA 94143, USA
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10
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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: 4] [Impact Index Per Article: 4.0] [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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11
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Abdulla AZ, Vaillant C, Jost D. Painters in chromatin: a unified quantitative framework to systematically characterize epigenome regulation and memory. Nucleic Acids Res 2022; 50:9083-9104. [PMID: 36018799 PMCID: PMC9458448 DOI: 10.1093/nar/gkac702] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/03/2022] [Indexed: 12/24/2022] Open
Abstract
In eukaryotes, many stable and heritable phenotypes arise from the same DNA sequence, owing to epigenetic regulatory mechanisms relying on the molecular cooperativity of 'reader-writer' enzymes. In this work, we focus on the fundamental, generic mechanisms behind the epigenome memory encoded by post-translational modifications of histone tails. Based on experimental knowledge, we introduce a unified modeling framework, the painter model, describing the mechanistic interplay between sequence-specific recruitment of chromatin regulators, chromatin-state-specific reader-writer processes and long-range spreading mechanisms. A systematic analysis of the model building blocks highlights the crucial impact of tridimensional chromatin organization and state-specific recruitment of enzymes on the stability of epigenomic domains and on gene expression. In particular, we show that enhanced 3D compaction of the genome and enzyme limitation facilitate the formation of ultra-stable, confined chromatin domains. The model also captures how chromatin state dynamics impact the intrinsic transcriptional properties of the region, slower kinetics leading to noisier expression. We finally apply our framework to analyze experimental data, from the propagation of γH2AX around DNA breaks in human cells to the maintenance of heterochromatin in fission yeast, illustrating how the painter model can be used to extract quantitative information on epigenomic molecular processes.
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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
| | - Cédric Vaillant
- Correspondence may also be addressed to Cédric Vaillant. Tel: +33 4 72 72 81 54; Fax: +33 4 72 72 80 00;
| | - Daniel Jost
- To whom correspondence should be addressed. Tel: +33 4 72 72 86 30; Fax: +33 4 72 72 80 00;
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12
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Kadam S, Bameta T, Padinhateeri R. Nucleosome sliding can influence the spreading of histone modifications. Phys Rev E 2022; 106:024408. [PMID: 36110002 DOI: 10.1103/physreve.106.024408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Nucleosomes are the fundamental building blocks of chromatin that not only help in the folding of chromatin, but also in carrying epigenetic information. It is known that nucleosome sliding is responsible for dynamically organizing chromatin structure and the resulting gene regulation. Since sliding can move two neighboring nucleosomes physically close or away, can it play a role in the spreading of histone modifications? We investigate this by simulating a stochastic model that couples nucleosome dynamics with the kinetics of histone modifications. We show that the sliding of nucleosomes can affect the modification pattern as well as the time it takes to modify a given region of chromatin. Exploring different nucleosome densities and modification kinetic parameters, we show that nucleosome sliding can be important for creating histone modification domains. Our model predicts that nucleosome density coupled with sliding dynamics can create an asymmetric histone modification profile around regulatory regions. We also compute the probability distribution of modified nucleosomes and relaxation kinetics of modifications. Our predictions are comparable with known experimental results.
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Affiliation(s)
- Shantanu Kadam
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Tripti Bameta
- Department of Medical Oncology, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai 410210, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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