1
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Meng L, Sheong FK, Luo Q. Linking DNA-packing density distribution and TAD boundary locations. Proc Natl Acad Sci U S A 2025; 122:e2418456122. [PMID: 39999165 PMCID: PMC11892626 DOI: 10.1073/pnas.2418456122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2024] [Accepted: 01/21/2025] [Indexed: 02/27/2025] Open
Abstract
DNA is heterogeneously packaged into chromatin, which is further organized into topologically associating domains (TADs) with sharp boundaries. These boundary locations are critical for genome regulation. Here, we explore how the distribution of DNA-packing density across chromatin affects the TAD boundary locations. We develop a polymer-physics-based model that utilizes DNA accessibility data to parameterize DNA-packing density along chromosomes, treating them as heteropolymers, and simulates the stochastic folding of these heteropolymers within a nucleus to yield a conformation ensemble. Such an ensemble reproduces a subset (over 60%) of TAD boundaries across the human genome, as confirmed by Hi-C data. Additionally, it reproduces the spatial distance matrices of 2-Mb genomic regions provided by FISH experiments. Furthermore, our model suggests that utilizing DNA accessibility data alone as input is sufficient to predict the emergence and disappearance of key TADs during early T cell differentiation. We show that stochastic folding of heteropolymers in a confined space can replicate both the prevalence of chromatin domain structures and the cell-to-cell variation in domain boundary positions observed in single-cell experiments. Furthermore, regions of lower DNA-packing density preferentially form domain boundaries, and this preference drives the emergence of TAD boundaries observed in ensemble-averaged Hi-C maps. The enrichment of TAD boundaries at CTCF binding sites can be attributed to the influence of CTCF binding on local DNA-packing density in our model. Collectively, our findings establish a strong link between TAD boundaries and regions of lower DNA-packing density, providing insights into the mechanisms underlying TAD formation.
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Affiliation(s)
- Luming Meng
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou510630, People’s Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou510630, People’s Republic of China
| | - Fu Kit Sheong
- Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong999077, People’s Republic of China
| | - Qiong Luo
- Center for Computational Quantum Chemistry, School of Chemistry, South China Normal University, Guangzhou510631, People’s Republic of China
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2
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Fontana A, Tafuri F, Abraham A, Bianco S, Esposito A, Conte M, Vercellone F, Pierno FD, Guha S, Carluccio CD, Chiariello AM. Polymer models of chromatin organization in virally infected cells. Biochem Soc Trans 2025; 53:BST20240598. [PMID: 39927819 DOI: 10.1042/bst20240598] [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: 01/28/2025] [Revised: 01/16/2025] [Accepted: 01/21/2025] [Indexed: 02/11/2025]
Abstract
Genome architecture is closely tied to essential biological functions, yet a complete understanding of the mechanisms governing DNA folding remains a significant challenge. Theoretical models based on polymer physics have been applied to decipher the complexity of chromatin architecture and uncover the physical processes shaping its structure. Importantly, recent findings suggest that certain viruses can alter the 3D organization of the host genome. In this review, we highlight recent advances in the development of polymer models used to study how chromatin 3D structure within a cell re-organizes following viral infection, with a particular emphasis on the SARS-CoV-2 virus, capable of altering genome organization of the host cell at different scales, including A/B compartments, TADs and gene-enhancer regulatory contacts.
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Affiliation(s)
- Andrea Fontana
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Fabrizio Tafuri
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Alex Abraham
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Simona Bianco
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Andrea Esposito
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Mattia Conte
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Francesca Vercellone
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale - DICMaPI, Università degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Naples, Italy
| | - Florinda Di Pierno
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale - DICMaPI, Università degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Naples, Italy
| | - Sougata Guha
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Ciro Di Carluccio
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale - DICMaPI, Università degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Naples, Italy
| | - Andrea M Chiariello
- Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
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3
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Conte M, Abraham A, Esposito A, Yang L, Gibcus JH, Parsi KM, Vercellone F, Fontana A, Di Pierno F, Dekker J, Nicodemi M. Polymer Physics Models Reveal Structural Folding Features of Single-Molecule Gene Chromatin Conformations. Int J Mol Sci 2024; 25:10215. [PMID: 39337699 PMCID: PMC11432541 DOI: 10.3390/ijms251810215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2024] [Revised: 09/17/2024] [Accepted: 09/22/2024] [Indexed: 09/30/2024] Open
Abstract
Here, we employ polymer physics models of chromatin to investigate the 3D folding of a 2 Mb wide genomic region encompassing the human LTN1 gene, a crucial DNA locus involved in key cellular functions. Through extensive Molecular Dynamics simulations, we reconstruct in silico the ensemble of single-molecule LTN1 3D structures, which we benchmark against recent in situ Hi-C 2.0 data. The model-derived single molecules are then used to predict structural folding features at the single-cell level, providing testable predictions for super-resolution microscopy experiments.
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Affiliation(s)
- Mattia Conte
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Alex Abraham
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Andrea Esposito
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Liyan Yang
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Johan H. Gibcus
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Krishna M. Parsi
- Diabetes Center of Excellence and Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
| | - Francesca Vercellone
- DIETI, Università di Napoli Federico II, Via Claudio 21, 80125 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Andrea Fontana
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Florinda Di Pierno
- DIETI, Università di Napoli Federico II, Via Claudio 21, 80125 Naples, Italy
- INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Job Dekker
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Mario Nicodemi
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
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4
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Conte M, Abraham A, Esposito A, Yang L, Gibcus JH, Parsi KM, Vercellone F, Fontana A, Pierno FD, Dekker J, Nicodemi M. Polymer physics models reveal structural folding features of single-molecule gene chromatin conformations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.16.603769. [PMID: 39071404 PMCID: PMC11275793 DOI: 10.1101/2024.07.16.603769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Here, we employ polymer physics models of chromatin to investigate the 3D folding of a 2Mb wide genomic region encompassing the human LTN1 gene, a crucial DNA locus involved in key cellular functions. Through extensive Molecular Dynamics simulations, we reconstruct in-silico the ensemble of single-molecule LTN1 3D structures, which we benchmark against recent in-situ Hi-C 2.0 data. The model-derived single molecules are then used to predict structural folding features at the single-cell level, providing testable predictions for super-resolution microscopy experiments.
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Affiliation(s)
- Mattia Conte
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Alex Abraham
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Andrea Esposito
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Liyan Yang
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Johan H. Gibcus
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Krishna M. Parsi
- Diabetes Center of Excellence and Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01655
| | - Francesca Vercellone
- DIETI, Università di Napoli Federico II, Via Claudio 21, 80125 Naples, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Andrea Fontana
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Florinda Di Pierno
- DIETI, Università di Napoli Federico II, Via Claudio 21, 80125 Naples, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
| | - Job Dekker
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Mario Nicodemi
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy
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5
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Wei J, Xue Y, Liu Y, Tian H, Shao Y, Gao YQ. Steric repulsion introduced by loop constraints modulates the microphase separation of chromatins. J Chem Phys 2024; 160:054904. [PMID: 38341710 DOI: 10.1063/5.0189692] [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: 11/30/2023] [Accepted: 01/15/2024] [Indexed: 02/13/2024] Open
Abstract
Within the confines of a densely populated cell nucleus, chromatin undergoes intricate folding, forming loops, domains, and compartments under the governance of topological constraints and phase separation. This coordinated process inevitably introduces interference between different folding strategies. In this study, we model interphase chromatins as block copolymers with hetero-hierarchical loops within a confined system. Employing dissipative particle dynamics simulations and scaling analysis, we aim to explain how the structure and distribution of loop domains modulate the microphase separation of chromatins. Our results highlight the correlation between the microphase separation of the copolymer and the length, heterogeneity, and hierarchically nested levels of the loop domains. This correlation arises from steric repulsion intrinsic to loop domains. The steric repulsion induces variations in chain stiffness (including local orientation correlations and the persistence length), thereby influencing the degree of phase separation. Through simulations of block copolymers with distinct groups of hetero-hierarchical loop anchors, we successfully reproduce changes in phase separation across diverse cell lines, under fixed interaction parameters. These findings, in qualitative alignment with Hi-C data, suggest that the variations of loop constraints alone possess the capacity to regulate higher-order structures and the gene expressions of interphase chromatins.
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Affiliation(s)
| | - Yue Xue
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China
| | - Yawei Liu
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Hao Tian
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China
| | - Yingfeng Shao
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yi Qin Gao
- Changping Laboratory, Beijing 102206, China
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China
- Shenzhen Bay Laboratory, 5F, No. 9 Duxue Rd., Nanshan District, Shenzhen 518055, Guangdong, China
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6
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Unveiling the Machinery behind Chromosome Folding by Polymer Physics Modeling. Int J Mol Sci 2023; 24:ijms24043660. [PMID: 36835064 PMCID: PMC9967178 DOI: 10.3390/ijms24043660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/06/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Understanding the mechanisms underlying the complex 3D architecture of mammalian genomes poses, at a more fundamental level, the problem of how two or multiple genomic sites can establish physical contacts in the nucleus of the cells. Beyond stochastic and fleeting encounters related to the polymeric nature of chromatin, experiments have revealed specific, privileged patterns of interactions that suggest the existence of basic organizing principles of folding. In this review, we focus on two major and recently proposed physical processes of chromatin organization: loop-extrusion and polymer phase-separation, both supported by increasing experimental evidence. We discuss their implementation into polymer physics models, which we test against available single-cell super-resolution imaging data, showing that both mechanisms can cooperate to shape chromatin structure at the single-molecule level. Next, by exploiting the comprehension of the underlying molecular mechanisms, we illustrate how such polymer models can be used as powerful tools to make predictions in silico that can complement experiments in understanding genome folding. To this aim, we focus on recent key applications, such as the prediction of chromatin structure rearrangements upon disease-associated mutations and the identification of the putative chromatin organizing factors that orchestrate the specificity of DNA regulatory contacts genome-wide.
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7
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Gong H, Li M, Ji M, Zhang X, Yuan Z, Zhang S, Yang Y, Li C, Chen Y. MINE is a method for detecting spatial density of regulatory chromatin interactions based on a multi-modal network. CELL REPORTS METHODS 2023; 3:100386. [PMID: 36814847 PMCID: PMC9939382 DOI: 10.1016/j.crmeth.2022.100386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/15/2022] [Accepted: 12/16/2022] [Indexed: 06/18/2023]
Abstract
Chromatin interactions play essential roles in chromatin conformation and gene expression. However, few tools exist to analyze the spatial density of regulatory chromatin interactions (SD-RCI). Here, we present the multi-modal network (MINE) toolkit, including MINE-Loop, MINE-Density, and MINE-Viewer. The MINE-Loop network aims to enhance the detection of RCIs, MINE-Density quantifies the SD--RCI, and MINE-Viewer facilitates 3D visualization of the density of chromatin interactions and participating regulatory factors (e.g., transcription factors). We applied MINE to investigate the relationship between the SD-RCI and chromatin volume change in HeLa cells before and after liquid-liquid phase separation. Changes in SD-RCI before and after treating the HeLa cells with 1,6-hexanediol suggest that changes in chromatin organization was related to the degree of activation or repression of genes. Together, the MINE toolkit enables quantitative studies on different aspects of chromatin conformation and regulatory activity.
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Affiliation(s)
- Haiyan Gong
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Minghong Li
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Mengdie Ji
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, School of Basic Medicine, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100005, China
| | - Xiaotong Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China
- Shunde Innovation School, University of Science and Technology Beijing, Foshan 528399, China
| | - Zan Yuan
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, School of Basic Medicine, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100005, China
| | - Sichen Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yi Yang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Chun Li
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yang Chen
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, School of Basic Medicine, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100005, China
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8
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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: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [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
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9
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Esposito A, Abraham A, Conte M, Vercellone F, Prisco A, Bianco S, Chiariello AM. The Physics of DNA Folding: Polymer Models and Phase-Separation. Polymers (Basel) 2022; 14:1918. [PMID: 35567087 PMCID: PMC9104579 DOI: 10.3390/polym14091918] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 04/23/2022] [Accepted: 04/27/2022] [Indexed: 02/04/2023] Open
Abstract
Within cell nuclei, several biophysical processes occur in order to allow the correct activities of the genome such as transcription and gene regulation. To quantitatively investigate such processes, polymer physics models have been developed to unveil the molecular mechanisms underlying genome functions. Among these, phase-separation plays a key role since it controls gene activity and shapes chromatin spatial structure. In this paper, we review some recent experimental and theoretical progress in the field and show that polymer physics in synergy with numerical simulations can be helpful for several purposes, including the study of molecular condensates, gene-enhancer dynamics, and the three-dimensional reconstruction of real genomic regions.
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Affiliation(s)
- Andrea Esposito
- Dipartimento di Fisica, Università di Napoli Federico II, INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy; (A.E.); (A.A.); (M.C.); (F.V.)
| | - Alex Abraham
- Dipartimento di Fisica, Università di Napoli Federico II, INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy; (A.E.); (A.A.); (M.C.); (F.V.)
| | - Mattia Conte
- Dipartimento di Fisica, Università di Napoli Federico II, INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy; (A.E.); (A.A.); (M.C.); (F.V.)
| | - Francesca Vercellone
- Dipartimento di Fisica, Università di Napoli Federico II, INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy; (A.E.); (A.A.); (M.C.); (F.V.)
| | | | - Simona Bianco
- Dipartimento di Fisica, Università di Napoli Federico II, INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy; (A.E.); (A.A.); (M.C.); (F.V.)
- Berlin Institute for Medical Systems Biology, Max-Delbrück Centre (MDC) for Molecular Medicine, 10115 Berlin, Germany
| | - Andrea M. Chiariello
- Dipartimento di Fisica, Università di Napoli Federico II, INFN Napoli, Complesso Universitario di Monte Sant’Angelo, 80126 Naples, Italy; (A.E.); (A.A.); (M.C.); (F.V.)
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10
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Laghmach R, Di Pierro M, Potoyan D. A Liquid State Perspective on Dynamics of Chromatin Compartments. Front Mol Biosci 2022; 8:781981. [PMID: 35096966 PMCID: PMC8793688 DOI: 10.3389/fmolb.2021.781981] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 12/22/2021] [Indexed: 12/11/2022] Open
Abstract
The interior of the eukaryotic cell nucleus has a crowded and heterogeneous environment packed with chromatin polymers, regulatory proteins, and RNA molecules. Chromatin polymer, assisted by epigenetic modifications, protein and RNA binders, forms multi-scale compartments which help regulate genes in response to cellular signals. Furthermore, chromatin compartments are dynamic and tend to evolve in size and composition in ways that are not fully understood. The latest super-resolution imaging experiments have revealed a much more dynamic and stochastic nature of chromatin compartments than was appreciated before. An emerging mechanism explaining chromatin compartmentalization dynamics is the phase separation of protein and nucleic acids into membraneless liquid condensates. Consequently, concepts and ideas from soft matter and polymer systems have been rapidly entering the lexicon of cell biology. In this respect, the role of computational models is crucial for establishing a rigorous and quantitative foundation for the new concepts and disentangling the complex interplay of forces that contribute to the emergent patterns of chromatin dynamics and organization. Several multi-scale models have emerged to address various aspects of chromatin dynamics, ranging from equilibrium polymer simulations, hybrid non-equilibrium simulations coupling protein binding and chromatin folding, and mesoscopic field-theoretic models. Here, we review these emerging theoretical paradigms and computational models with a particular focus on chromatin’s phase separation and liquid-like properties as a basis for nuclear organization and dynamics.
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Affiliation(s)
- Rabia Laghmach
- Department of Chemistry, Iowa State University, Ames, IA, United States
| | - Michele Di Pierro
- Department of Physics, Northeastern University, Boston, MA, United States
| | - Davit Potoyan
- Department of Chemistry, Iowa State University, Ames, IA, United States
- *Correspondence: Davit Potoyan,
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11
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Esposito A, Bianco S, Fiorillo L, Conte M, Abraham A, Musella F, Nicodemi M, Prisco A, Chiariello AM. Polymer models are a versatile tool to study chromatin 3D organization. Biochem Soc Trans 2021; 49:1675-1684. [PMID: 34282837 DOI: 10.1042/bst20201004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/21/2021] [Accepted: 06/25/2021] [Indexed: 11/17/2022]
Abstract
The development of new experimental technologies is opening the way to a deeper investigation of the three-dimensional organization of chromosomes inside the cell nucleus. Genome architecture is linked to vital functional purposes, yet a full comprehension of the mechanisms behind DNA folding is still far from being accomplished. Theoretical approaches based on polymer physics have been employed to understand the complexity of chromatin architecture data and to unveil the basic mechanisms shaping its structure. Here, we review some recent advances in the field to discuss how Polymer Physics, combined with numerical Molecular Dynamics simulation and Machine Learning based inference, can capture important aspects of genome organization, including the description of tissue-specific structural rearrangements, the detection of novel, regulatory-linked architectural elements and the structural variability of chromatin at the single-cell level.
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Affiliation(s)
- Andrea Esposito
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Simona Bianco
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- Berlin Institute for Medical Systems Biology, Max-Delbrück Centre (MDC) for Molecular Medicine, Berlin, Germany
| | - Luca Fiorillo
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Mattia Conte
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Alex Abraham
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Francesco Musella
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
| | - Mario Nicodemi
- Berlin Institute for Medical Systems Biology, Max-Delbrück Centre (MDC) for Molecular Medicine, Berlin, Germany
- Dipartimento di Fisica, Università di Napoli Federico II, INFN Napoli, CNR-SPIN, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
- Berlin Institute of Health (BIH), MDC-Berlin, Germany
| | | | - Andrea M Chiariello
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126 Naples, Italy
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Wei J, Tian H, Zhou R, Shao Y, Song F, Gao YQ. Topological Constraints with Optimal Length Promote the Formation of Chromosomal Territories at Weakened Degree of Phase Separation. J Phys Chem B 2021; 125:9092-9101. [PMID: 34351763 DOI: 10.1021/acs.jpcb.1c03523] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is generally agreed that the nuclei of eukaryotic cells at interphase are partitioned into disjointed territories, with distinct regions occupied by certain chromosomes. However, the underlying mechanism for such territorialization is still under debate. Here we model chromosomes as coarse-grained block copolymers and to investigate the effect of loop domains (LDs) on the formation of compartments and territories based on dissipative particle dynamics. A critical length of LDs, which depends sensitively on the length of polymeric blocks, is obtained to minimize the degree of phase separation. This also applies to the two-polymer system: The critical length not only maximizes the degree of territorialization but also minimizes the degree of phase separation. Interestingly, by comparing with experimental data, we find the critical length for LDs and the corresponding length of blocks to be respectively very close to the mean length of topologically associating domains (TADs) and chromosomal segments with different densities of CpG islands for human chromosomes. The results indicate that topological constraints with optimal length can contribute to the formation of territories by weakening the degree of phase separation, which likely promotes the chromosomal flexibility in response to genetic regulations.
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Affiliation(s)
- Jiachen Wei
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.,Shenzhen Bay Laboratory, 5F, No. 9 Duxue Road, Nanshan District, 518055 Shenzhen, Guangdong, China
| | - Hao Tian
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China.,Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing 100871, China
| | - Rui Zhou
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China.,Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing 100871, China
| | - Yingfeng Shao
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi Qin Gao
- Shenzhen Bay Laboratory, 5F, No. 9 Duxue Road, Nanshan District, 518055 Shenzhen, Guangdong, China.,Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China.,Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing 100871, China
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13
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Chiariello AM, Corberi F, Salerno M. The Interplay between Phase Separation and Gene-Enhancer Communication: A Theoretical Study. Biophys J 2020; 119:873-883. [PMID: 32738219 PMCID: PMC7451901 DOI: 10.1016/j.bpj.2020.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022] Open
Abstract
The phase separation occurring in a system of mutually interacting proteins that can bind on specific sites of a chromatin fiber is investigated here. This is achieved by means of extensive molecular dynamics simulations of a simple polymer model that includes regulatory proteins as interacting spherical particles. Our interest is particularly focused on the role played by phase separation in the formation of molecule aggregates that can join distant regulatory elements, such as gene promoters and enhancers, along the DNA. We find that the overall equilibrium state of the system resulting from the mutual interplay between binding molecules and chromatin can lead, under suitable conditions that depend on molecules concentration, molecule-molecule, and molecule-DNA interactions, to the formation of phase-separated molecular clusters, allowing robust contacts between regulatory sites. Vice versa, the presence of regulatory sites can promote the phase-separation process. Different dynamical regimes can generate the enhancer-promoter contact, either by cluster nucleation at binding sites or by bulk spontaneous formation of the mediating cluster to which binding sites are successively attracted. The possibility that such processes can explain experimental live-cell imaging data measuring distances between regulatory sites during time is also discussed.
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Affiliation(s)
- Andrea M Chiariello
- Dipartimento di Fisica "E.R. Caianiello" and INFN, Gruppo Collegato di Salerno, Università di Salerno, Fisciano, Italy; Dipartimento di Fisica "Ettore Pancini," Università degli Studi di Napoli Federico II, and INFN Sezione di Napoli, Complesso Universitario di Monte Sant'Angelo, Naples, Italy.
| | - Federico Corberi
- Dipartimento di Fisica "E.R. Caianiello" and INFN, Gruppo Collegato di Salerno, Università di Salerno, Fisciano, Italy
| | - Mario Salerno
- Dipartimento di Fisica "E.R. Caianiello" and INFN, Gruppo Collegato di Salerno, Università di Salerno, Fisciano, Italy
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