1
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Arroyo M, Casas-Delucchi CS, Pabba MK, Prorok P, Pradhan SK, Rausch C, Lehmkuhl A, Maiser A, Buschbeck M, Pasque V, Bernstein E, Luck K, Cardoso MC. Histone variant macroH2A1 regulates synchronous firing of replication origins in the inactive X chromosome. Nucleic Acids Res 2024:gkae734. [PMID: 39189450 DOI: 10.1093/nar/gkae734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 08/07/2024] [Accepted: 08/14/2024] [Indexed: 08/28/2024] Open
Abstract
MacroH2A has been linked to transcriptional silencing, cell identity, and is a hallmark of the inactive X chromosome (Xi). However, it remains unclear whether macroH2A plays a role in DNA replication. Using knockdown/knockout cells for each macroH2A isoform, we show that macroH2A-containing nucleosomes slow down replication progression rate in the Xi reflecting the higher nucleosome stability. Moreover, macroH2A1, but not macroH2A2, regulates the number of nano replication foci in the Xi, and macroH2A1 downregulation increases DNA loop sizes corresponding to replicons. This relates to macroH2A1 regulating replicative helicase loading during G1 by interacting with it. We mapped this interaction to a phenylalanine in macroH2A1 that is not conserved in macroH2A2 and the C-terminus of Mcm3 helicase subunit. We propose that macroH2A1 enhances the licensing of pre-replication complexes via DNA helicase interaction and loading onto the Xi.
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Affiliation(s)
- Maria Arroyo
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Corella S Casas-Delucchi
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Maruthi K Pabba
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Paulina Prorok
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Sunil K Pradhan
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Cathia Rausch
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Anne Lehmkuhl
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Andreas Maiser
- Faculty of Biology and Center for Molecular Biosystems (BioSysM), Human Biology and BioImaging, LMU Munich, Munich 81377, Germany
| | - Marcus Buschbeck
- Program of Myeloid Neoplasms, Program of Applied Epigenetics, Josep Carreras Leukaemia Research Institute (IJC), Germans Trias i Pujol Research Institute (IGTP), Campus Can Ruti, Camí de les Escoles, 08916 Badalona, Barcelona, Spain
| | - Vincent Pasque
- Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Institute for Single-Cell Omics (LISCO), KU Leuven-University of Leuven, 3000 Leuven, Belgium
| | - Emily Bernstein
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, Tisch Cancer Institute, NY, NY 10029, USA
| | - Katja Luck
- Institute of Molecular Biology (IMB) gGmbH, 55128 Mainz, Germany
| | - M Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
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2
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Wang Z, Tian W, Guo Y, Wang D, Zhang Y, Zhi Y, Li D, Li W, Li Z, Jiang R, Han R, Sun G, Li G, Tian Y, Li H, Kang X, Liu X. Dynamic alternations of three-dimensional chromatin architecture contribute to phenotypic characteristics of breast muscle in chicken. Commun Biol 2024; 7:910. [PMID: 39068219 PMCID: PMC11283561 DOI: 10.1038/s42003-024-06599-3] [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: 10/15/2023] [Accepted: 07/17/2024] [Indexed: 07/30/2024] Open
Abstract
Breast muscle growth rate and intramuscular fat (IMF) content show apparent differences between fast-growing broilers and slow-growing indigenous chickens. However, the underlying genetic basis of these phenotypic characteristics remains elusive. In this study, we investigate the dynamic alterations of three-dimensional genome architecture and chromatin accessibility in breast muscle across four key developmental stages from embryo to starter chick in Arbor Acres (AA) broilers and Yufen (YF) indigenous chickens. The limited breed-specifically up-regulated genes (Bup-DEGs) are embedded in breed-specific A compartment, while a majority of the Bup-DEGs involving myogenesis and adipogenesis are regulated by the breed-specific TAD reprogramming. Chromatin loops allow distal accessible regions to interact with myogenic genes, and those loops share an extremely low similarity between chicken with different growth rate. Moreover, AA-specific loop interactions promote the expression of 40 Bup-DEGs, such as IGF1, which contributes to myofiber hypertrophy. YF-specific loop interactions or distal accessible regions lead to increased expression of 5 Bup-DEGs, including PIGO, PEMT, DHCR7, TMEM38B, and DHDH, which contribute to IMF deposition. These results help elucidate the regulation of breast muscle growth and IMF deposition in chickens.
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Affiliation(s)
- Zhang Wang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
| | - Weihua Tian
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
| | - Yulong Guo
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
| | - Dandan Wang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
| | - Yanyan Zhang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
| | - Yihao Zhi
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
| | - Donghua Li
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Wenting Li
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Zhuanjian Li
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Ruirui Jiang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Ruili Han
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Guirong Sun
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Guoxi Li
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Yadong Tian
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China
| | - Hong Li
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China.
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China.
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China.
| | - Xiangtao Kang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China.
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China.
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China.
| | - Xiaojun Liu
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450002, China.
- Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, 450002, China.
- International Joint Research, Laboratory for Poultry Breeding of Henan, Zhengzhou, 450002, China.
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3
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Pabba MK, Meyer J, Celikay K, Schermelleh L, Rohr K, Cardoso MC. DNA choreography: correlating mobility and organization of DNA across different resolutions from loops to chromosomes. Histochem Cell Biol 2024; 162:109-131. [PMID: 38758428 PMCID: PMC11227476 DOI: 10.1007/s00418-024-02285-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2024] [Indexed: 05/18/2024]
Abstract
The dynamics of DNA in the cell nucleus plays a role in cellular processes and fates but the interplay of DNA mobility with the hierarchical levels of DNA organization is still underexplored. Here, we made use of DNA replication to directly label genomic DNA in an unbiased genome-wide manner. This was followed by live-cell time-lapse microscopy of the labeled DNA combining imaging at different resolutions levels simultaneously and allowing one to trace DNA motion across organization levels within the same cells. Quantification of the labeled DNA segments at different microscopic resolution levels revealed sizes comparable to the ones reported for DNA loops using 3D super-resolution microscopy, topologically associated domains (TAD) using 3D widefield microscopy, and also entire chromosomes. By employing advanced chromatin tracking and image registration, we discovered that DNA exhibited higher mobility at the individual loop level compared to the TAD level and even less at the chromosome level. Additionally, our findings indicate that chromatin movement, regardless of the resolution, slowed down during the S phase of the cell cycle compared to the G1/G2 phases. Furthermore, we found that a fraction of DNA loops and TADs exhibited directed movement with the majority depicting constrained movement. Our data also indicated spatial mobility differences with DNA loops and TADs at the nuclear periphery and the nuclear interior exhibiting lower velocity and radius of gyration than the intermediate locations. On the basis of these insights, we propose that there is a link between DNA mobility and its organizational structure including spatial distribution, which impacts cellular processes.
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Affiliation(s)
- Maruthi K Pabba
- Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Janis Meyer
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany
| | - Kerem Celikay
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany
| | | | - Karl Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany.
| | - M Cristina Cardoso
- Department of Biology, Technical University of Darmstadt, Darmstadt, Germany.
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4
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Chan B, Rubinstein M. Activity-driven chromatin organization during interphase: Compaction, segregation, and entanglement suppression. Proc Natl Acad Sci U S A 2024; 121:e2401494121. [PMID: 38753513 PMCID: PMC11127048 DOI: 10.1073/pnas.2401494121] [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: 01/26/2024] [Accepted: 04/17/2024] [Indexed: 05/18/2024] Open
Abstract
In mammalian cells, the cohesin protein complex is believed to translocate along chromatin during interphase to form dynamic loops through a process called active loop extrusion. Chromosome conformation capture and imaging experiments have suggested that chromatin adopts a compact structure with limited interpenetration between chromosomes and between chromosomal sections. We developed a theory demonstrating that active loop extrusion causes the apparent fractal dimension of chromatin to cross-over between two and four at contour lengths on the order of 30 kilo-base pairs. The anomalously high fractal dimension [Formula: see text] is due to the inability of extruded loops to fully relax during active extrusion. Compaction on longer contour length scales extends within topologically associated domains (TADs), facilitating gene regulation by distal elements. Extrusion-induced compaction segregates TADs such that overlaps between TADs are reduced to less than 35% and increases the entanglement strand of chromatin by up to a factor of 50 to several Mega-base pairs. Furthermore, active loop extrusion couples cohesin motion to chromatin conformations formed by previously extruding cohesins and causes the mean square displacement of chromatin loci during lag times ([Formula: see text]) longer than tens of minutes to be proportional to [Formula: see text]. We validate our results with hybrid molecular dynamics-Monte Carlo simulations and show that our theory is consistent with experimental data. This work provides a theoretical basis for the compact organization of interphase chromatin, explaining the physical reason for TAD segregation and suppression of chromatin entanglements which contribute to efficient gene regulation.
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Affiliation(s)
- Brian Chan
- Department of Biomedical Engineering, Duke University, Durham, NC27708
| | - Michael Rubinstein
- Department of Biomedical Engineering, Duke University, Durham, NC27708
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC27708
- Department of Physics, Duke University, Durham, NC27708
- Department of Chemistry, Duke University, Durham, NC27708
- World Premier International Research Center Initiative–Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo001-0021, Japan
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5
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Daugird TA, Shi Y, Holland KL, Rostamian H, Liu Z, Lavis LD, Rodriguez J, Strahl BD, Legant WR. Correlative single molecule lattice light sheet imaging reveals the dynamic relationship between nucleosomes and the local chromatin environment. Nat Commun 2024; 15:4178. [PMID: 38755200 PMCID: PMC11099156 DOI: 10.1038/s41467-024-48562-0] [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: 11/21/2023] [Accepted: 05/03/2024] [Indexed: 05/18/2024] Open
Abstract
In the nucleus, biological processes are driven by proteins that diffuse through and bind to a meshwork of nucleic acid polymers. To better understand this interplay, we present an imaging platform to simultaneously visualize single protein dynamics together with the local chromatin environment in live cells. Together with super-resolution imaging, new fluorescent probes, and biophysical modeling, we demonstrate that nucleosomes display differential diffusion and packing arrangements as chromatin density increases whereas the viscoelastic properties and accessibility of the interchromatin space remain constant. Perturbing nuclear functions impacts nucleosome diffusive properties in a manner that is dependent both on local chromatin density and on relative location within the nucleus. Our results support a model wherein transcription locally stabilizes nucleosomes while simultaneously allowing for the free exchange of nuclear proteins. Additionally, they reveal that nuclear heterogeneity arises from both active and passive processes and highlight the need to account for different organizational principles when modeling different chromatin environments.
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Affiliation(s)
- Timothy A Daugird
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Yu Shi
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, North Carolina State University, Chapel Hill, NC, USA
| | - Katie L Holland
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA
| | - Hosein Rostamian
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA
| | - Joseph Rodriguez
- National Institute of Environmental Health Sciences, Durham, NC, 27709, USA
| | - Brian D Strahl
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Wesley R Legant
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, North Carolina State University, Chapel Hill, NC, USA.
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6
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Shan L, Chen LL. Unveiling the mystery of nuclear RNA homeostasis. Cell Stem Cell 2024; 31:583-585. [PMID: 38701751 DOI: 10.1016/j.stem.2024.03.014] [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: 03/19/2024] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 05/05/2024]
Abstract
How nuclear RNA homeostasis impacts cellular functions remains elusive. In this issue of Cell Stem Cell, Han et al.1 utilized a controllable protein degradation system targeting EXOSC2 to perturb RNA homeostasis in mouse pluripotent embryonic stem cells, revealing its vital role in orchestrating crucial nuclear events for cellular fitness.
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Affiliation(s)
- Lin Shan
- Key Laboratory of RNA Innovation, Science and Engineering, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ling-Ling Chen
- Key Laboratory of RNA Innovation, Science and Engineering, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China; Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China; School of Life Science and Technology, ShanghaiTech University, Shanghai, China; New Cornerstone Science Laboratory, Shenzhen, China.
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7
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Daugird TA, Shi Y, Holland KL, Rostamian H, Liu Z, Lavis LD, Rodriguez J, Strahl BD, Legant WR. Correlative single molecule lattice light sheet imaging reveals the dynamic relationship between nucleosomes and the local chromatin environment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.09.566470. [PMID: 38014222 PMCID: PMC10680651 DOI: 10.1101/2023.11.09.566470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
In the nucleus, biological processes are driven by proteins that diffuse through and bind to a meshwork of nucleic acid polymers. To better understand this interplay, we developed an imaging platform to simultaneously visualize single protein dynamics together with the local chromatin environment in live cells. Together with super-resolution imaging, new fluorescent probes, and biophysical modeling, we demonstrated that nucleosomes display differential diffusion and packing arrangements as chromatin density increases whereas the viscoelastic properties and accessibility of the interchromatin space remain constant. Perturbing nuclear functions impacted nucleosome diffusive properties in a manner that was dependent on local chromatin density and supportive of a model wherein transcription locally stabilizes nucleosomes while simultaneously allowing for the free exchange of nuclear proteins. Our results reveal that nuclear heterogeneity arises from both active and passive process and highlights the need to account for different organizational principals when modeling different chromatin environments.
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8
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García Fernández F, Huet S, Miné-Hattab J. Multi-Scale Imaging of the Dynamic Organization of Chromatin. Int J Mol Sci 2023; 24:15975. [PMID: 37958958 PMCID: PMC10649806 DOI: 10.3390/ijms242115975] [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: 09/19/2023] [Revised: 10/27/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
Chromatin is now regarded as a heterogeneous and dynamic structure occupying a non-random position within the cell nucleus, where it plays a key role in regulating various functions of the genome. This current view of chromatin has emerged thanks to high spatiotemporal resolution imaging, among other new technologies developed in the last decade. In addition to challenging early assumptions of chromatin being regular and static, high spatiotemporal resolution imaging made it possible to visualize and characterize different chromatin structures such as clutches, domains and compartments. More specifically, super-resolution microscopy facilitates the study of different cellular processes at a nucleosome scale, providing a multi-scale view of chromatin behavior within the nucleus in different environments. In this review, we describe recent imaging techniques to study the dynamic organization of chromatin at high spatiotemporal resolution. We also discuss recent findings, elucidated by these techniques, on the chromatin landscape during different cellular processes, with an emphasis on the DNA damage response.
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Affiliation(s)
- Fabiola García Fernández
- Laboratory of Computational and Quantitative Biology, CNRS, Institut de Biologie Paris-Seine, Sorbonne Université, 75005 Paris, France;
| | - Sébastien Huet
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes)-UMR 6290, BIOSIT-UMS 3480, 35000 Rennes, France;
- Institut Universitaire de France, 75231 Paris, France
| | - Judith Miné-Hattab
- Laboratory of Computational and Quantitative Biology, CNRS, Institut de Biologie Paris-Seine, Sorbonne Université, 75005 Paris, France;
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9
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Pabba MK, Ritter C, Chagin VO, Meyer J, Celikay K, Stear JH, Loerke D, Kolobynina K, Prorok P, Schmid AK, Leonhardt H, Rohr K, Cardoso MC. Replisome loading reduces chromatin motion independent of DNA synthesis. eLife 2023; 12:RP87572. [PMID: 37906089 PMCID: PMC10617993 DOI: 10.7554/elife.87572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023] Open
Abstract
Chromatin has been shown to undergo diffusional motion, which is affected during gene transcription by RNA polymerase activity. However, the relationship between chromatin mobility and other genomic processes remains unclear. Hence, we set out to label the DNA directly in a sequence unbiased manner and followed labeled chromatin dynamics in interphase human cells expressing GFP-tagged proliferating cell nuclear antigen (PCNA), a cell cycle marker and core component of the DNA replication machinery. We detected decreased chromatin mobility during the S-phase compared to G1 and G2 phases in tumor as well as normal diploid cells using automated particle tracking. To gain insight into the dynamical organization of the genome during DNA replication, we determined labeled chromatin domain sizes and analyzed their motion in replicating cells. By correlating chromatin mobility proximal to the active sites of DNA synthesis, we showed that chromatin motion was locally constrained at the sites of DNA replication. Furthermore, inhibiting DNA synthesis led to increased loading of DNA polymerases. This was accompanied by accumulation of the single-stranded DNA binding protein on the chromatin and activation of DNA helicases further restricting local chromatin motion. We, therefore, propose that it is the loading of replisomes but not their catalytic activity that reduces the dynamics of replicating chromatin segments in the S-phase as well as their accessibility and probability of interactions with other genomic regions.
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Affiliation(s)
| | - Christian Ritter
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg UniversityHeidelbergGermany
| | - Vadim O Chagin
- Department of Biology, Technical University of DarmstadtDarmstadtGermany
- Institute of Cytology RASSt. PetersburgRussian Federation
| | - Janis Meyer
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg UniversityHeidelbergGermany
| | - Kerem Celikay
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg UniversityHeidelbergGermany
| | - Jeffrey H Stear
- EMBL Australia Node in Single Molecule Science, University of New South WalesSydneyAustralia
| | - Dinah Loerke
- Department of Physics & Astronomy, University of DenverDenverUnited States
| | - Ksenia Kolobynina
- Department of Biology, Technical University of DarmstadtDarmstadtGermany
| | - Paulina Prorok
- Department of Biology, Technical University of DarmstadtDarmstadtGermany
| | - Alice Kristin Schmid
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg UniversityHeidelbergGermany
| | | | - Karl Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg UniversityHeidelbergGermany
| | - M Cristina Cardoso
- Department of Biology, Technical University of DarmstadtDarmstadtGermany
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10
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Wu J, Liu Y, Zhangding Z, Liu X, Ai C, Gan T, Liang H, Guo Y, Chen M, Liu Y, Yin J, Zhang W, Hu J. Cohesin maintains replication timing to suppress DNA damage on cancer genes. Nat Genet 2023; 55:1347-1358. [PMID: 37500731 DOI: 10.1038/s41588-023-01458-z] [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: 09/29/2022] [Accepted: 06/26/2023] [Indexed: 07/29/2023]
Abstract
Cohesin loss-of-function mutations are frequently observed in tumors, but the mechanism underlying its role in tumorigenesis is unclear. Here, we found that depletion of RAD21, a core subunit of cohesin, leads to massive genome-wide DNA breaks and 147 translocation hotspot genes, co-mutated with cohesin in multiple cancers. Increased DNA damages are independent of RAD21-loss-induced transcription alteration and loop anchor disruption. However, damage-induced chromosomal translocations coincide with the asymmetrically distributed Okazaki fragments of DNA replication, suggesting that RAD21 depletion causes replication stresses evidenced by the slower replication speed and increased stalled forks. Mechanistically, approximately 30% of the human genome exhibits an earlier replication timing after RAD21 depletion, caused by the early initiation of >900 extra dormant origins. Correspondingly, most translocation hotspot genes lie in timing-altered regions. Therefore, we conclude that cohesin dysfunction causes replication stresses induced by excessive DNA replication initiation, resulting in gross DNA damages that may promote tumorigenesis.
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Affiliation(s)
- Jinchun Wu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Yang Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Zhengrong Zhangding
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Xuhao Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Chen Ai
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Tingting Gan
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Haoxin Liang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Yuefeng Guo
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Mohan Chen
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Yiyang Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Jianhang Yin
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Weiwei Zhang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Jiazhi Hu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China.
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11
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Gelléri M, Chen SY, Hübner B, Neumann J, Kröger O, Sadlo F, Imhoff J, Hendzel MJ, Cremer M, Cremer T, Strickfaden H, Cremer C. True-to-scale DNA-density maps correlate with major accessibility differences between active and inactive chromatin. Cell Rep 2023; 42:112567. [PMID: 37243597 DOI: 10.1016/j.celrep.2023.112567] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 03/02/2023] [Accepted: 05/10/2023] [Indexed: 05/29/2023] Open
Abstract
Chromatin compaction differences may have a strong impact on accessibility of individual macromolecules and macromolecular assemblies to their DNA target sites. Estimates based on fluorescence microscopy with conventional resolution, however, suggest only modest compaction differences (∼2-10×) between the active nuclear compartment (ANC) and inactive nuclear compartment (INC). Here, we present maps of nuclear landscapes with true-to-scale DNA densities, ranging from <5 to >300 Mbp/μm3. Maps are generated from individual human and mouse cell nuclei with single-molecule localization microscopy at ∼20 nm lateral and ∼100 nm axial optical resolution and are supplemented by electron spectroscopic imaging. Microinjection of fluorescent nanobeads with sizes corresponding to macromolecular assemblies for transcription into nuclei of living cells demonstrates their localization and movements within the ANC and exclusion from the INC.
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Affiliation(s)
- Márton Gelléri
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany.
| | - Shih-Ya Chen
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Barbara Hübner
- Biocenter, Department Biology II, Ludwig Maximilian University (LMU), 82152 Martinsried, Germany
| | - Jan Neumann
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany; Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - Ole Kröger
- Interdisciplinary Center for Scientific Computing (IWR), University Heidelberg, 69120 Heidelberg, Germany
| | - Filip Sadlo
- Interdisciplinary Center for Scientific Computing (IWR), University Heidelberg, 69120 Heidelberg, Germany
| | - Jorg Imhoff
- Neuroconsult GmbH, 69120 Heidelberg, Germany
| | - Michael J Hendzel
- Departments of Cell Biology and Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 1Z2, Canada
| | - Marion Cremer
- Biocenter, Department Biology II, Ludwig Maximilian University (LMU), 82152 Martinsried, Germany
| | - Thomas Cremer
- Biocenter, Department Biology II, Ludwig Maximilian University (LMU), 82152 Martinsried, Germany
| | - Hilmar Strickfaden
- Departments of Cell Biology and Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 1Z2, Canada.
| | - Christoph Cremer
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany; Max Planck Institute for Chemistry, 55128 Mainz, Germany; Interdisciplinary Center for Scientific Computing (IWR), University Heidelberg, 69120 Heidelberg, Germany; Kirchhoff Institute for Physics, University Heidelberg, 69120 Heidelberg, Germany.
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12
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Wang J, Nakato R. Comprehensive multiomics analyses reveal pervasive involvement of aberrant cohesin binding in transcriptional and chromosomal disorder of cancer cells. iScience 2023; 26:106908. [PMID: 37283809 PMCID: PMC10239702 DOI: 10.1016/j.isci.2023.106908] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 02/27/2023] [Accepted: 05/12/2023] [Indexed: 06/08/2023] Open
Abstract
Chromatin organization, whose malfunction causes various diseases including cancer, is fundamentally controlled by cohesin. While cancer cells have been found with mutated or misexpressed cohesin genes, there is no comprehensive survey about the presence and role of abnormal cohesin binding in cancer cells. Here, we systematically identified ∼1% of cohesin-binding sites (701-2,633) as cancer-aberrant binding sites of cohesin (CASs). We integrated CASs with large-scale transcriptomics, epigenomics, 3D genomics, and clinical information. CASs represent tissue-specific epigenomic signatures enriched for cancer-dysregulated genes with functional and clinical significance. CASs exhibited alterations in chromatin compartments, loops within topologically associated domains, and cis-regulatory elements, indicating that CASs induce dysregulated genes through misguided chromatin structure. Cohesin depletion data suggested that cohesin binding at CASs actively regulates cancer-dysregulated genes. Overall, our comprehensive investigation suggests that aberrant cohesin binding is an essential epigenomic signature responsible for dysregulated chromatin structure and transcription in cancer cells.
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Affiliation(s)
- Jiankang Wang
- School of Biomedical Sciences, Hunan University, Changsha, China
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Ryuichiro Nakato
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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13
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Chan B, Rubinstein M. Theory of chromatin organization maintained by active loop extrusion. Proc Natl Acad Sci U S A 2023; 120:e2222078120. [PMID: 37253009 PMCID: PMC10266055 DOI: 10.1073/pnas.2222078120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 04/13/2023] [Indexed: 06/01/2023] Open
Abstract
The active loop extrusion hypothesis proposes that chromatin threads through the cohesin protein complex into progressively larger loops until reaching specific boundary elements. We build upon this hypothesis and develop an analytical theory for active loop extrusion which predicts that loop formation probability is a nonmonotonic function of loop length and describes chromatin contact probabilities. We validate our model with Monte Carlo and hybrid Molecular Dynamics-Monte Carlo simulations and demonstrate that our theory recapitulates experimental chromatin conformation capture data. Our results support active loop extrusion as a mechanism for chromatin organization and provide an analytical description of chromatin organization that may be used to specifically modify chromatin contact probabilities.
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Affiliation(s)
- Brian Chan
- Department of Biomedical Engineering, Duke University, Durham, NC27708
| | - Michael Rubinstein
- Department of Biomedical Engineering, Duke University, Durham, NC27708
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC27708
- Department of Chemistry, Duke University, Durham, NC27708
- Department of Physics, Duke University, Durham, NC27708
- Institute for Chemical Reaction Design and Discovery (World Premier International Research Center Initiative-ICReDD), Hokkaido University, Sapporo001-0021, Japan
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14
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Zhou XL, Wei Y, Chen P, Yang X, Lu C, Pan MH. A novel transcription factor, BmZFP67, regulates endomitosis switch by controlling the expression of cyclin B in silk glands. Int J Biol Macromol 2023:124931. [PMID: 37263320 DOI: 10.1016/j.ijbiomac.2023.124931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 04/25/2023] [Accepted: 05/06/2023] [Indexed: 06/03/2023]
Abstract
Endomitosis is involved in developmental processes associated with an increase in metabolic cell activity, which is characterized by repeated rounds of DNA replication without cytokinesis. Endomitosis cells are widespread in protozoa, plants, animals and humans. Endomitosis cell cycle is currently viewed as a variation of the canonical cell cycle and transformed from mitotic cell cycle. However, the meaningful question about how endomitosis transformed from mitosis is still unclear. Herein, we identified a novel transcription factor in silk glands, ZFP67, which is gradually reduced in silk glands during the transition of mitosis to endomitosis. In addition, over-expressed ZFP67 in silk glands led to the transition delayed. And, knock-out of ZFP67 led to abnormal chromatin division and unsuccessful cell division. These data reveled that ZFP67 played an important role in transition of mitosis to endomitosis. Furthermore, ZFP67 can regulate the transcription of cyclin B, a key cyclin related to cell division and G2/M phase, which is demonstrated by chromatin immunoprecipitation and dual luciferase reporter system in this article. In conclusion, it can be speculated that the decreasing expression of ZFP67 in silk glands during the transition stage of mitosis-to-endomitosis resulted in the lack of cyclin B, which further led to unsuccessful cytokinesis and then promoted the transition from mitosis to endomitosis of silk gland cells.
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Affiliation(s)
- Xiao-Lin Zhou
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325001, China
| | - Yi Wei
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325001, China
| | - Peng Chen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China
| | - Xi Yang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Cheng Lu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China.
| | - Min-Hui Pan
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China.
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15
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Kabirova E, Nurislamov A, Shadskiy A, Smirnov A, Popov A, Salnikov P, Battulin N, Fishman V. Function and Evolution of the Loop Extrusion Machinery in Animals. Int J Mol Sci 2023; 24:5017. [PMID: 36902449 PMCID: PMC10003631 DOI: 10.3390/ijms24055017] [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: 02/07/2023] [Revised: 02/25/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Structural maintenance of chromosomes (SMC) complexes are essential proteins found in genomes of all cellular organisms. Essential functions of these proteins, such as mitotic chromosome formation and sister chromatid cohesion, were discovered a long time ago. Recent advances in chromatin biology showed that SMC proteins are involved in many other genomic processes, acting as active motors extruding DNA, which leads to the formation of chromatin loops. Some loops formed by SMC proteins are highly cell type and developmental stage specific, such as SMC-mediated DNA loops required for VDJ recombination in B-cell progenitors, or dosage compensation in Caenorhabditis elegans and X-chromosome inactivation in mice. In this review, we focus on the extrusion-based mechanisms that are common for multiple cell types and species. We will first describe an anatomy of SMC complexes and their accessory proteins. Next, we provide biochemical details of the extrusion process. We follow this by the sections describing the role of SMC complexes in gene regulation, DNA repair, and chromatin topology.
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Affiliation(s)
- Evelyn Kabirova
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Artem Nurislamov
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Artem Shadskiy
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Alexander Smirnov
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Andrey Popov
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Pavel Salnikov
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Nariman Battulin
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Veniamin Fishman
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
- Artificial Intelligence Research Institute (AIRI), 121108 Moscow, Russia
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16
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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: 1.0] [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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17
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Regulation associated modules reflect 3D genome modularity associated with chromatin activity. Nat Commun 2022; 13:5281. [PMID: 36075900 PMCID: PMC9458634 DOI: 10.1038/s41467-022-32911-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 08/19/2022] [Indexed: 12/02/2022] Open
Abstract
The 3D genome has been shown to be organized into modules including topologically associating domains (TADs) and compartments that are primarily defined by spatial contacts from Hi-C. There exists a gap to investigate whether and how the spatial modularity of the chromatin is related to the functional modularity resulting from chromatin activity. Despite histone modifications reflecting chromatin activity, inferring spatial modularity of the genome directly from the histone modification patterns has not been well explored. Here, we report that histone modifications show a modular pattern (referred to as regulation associated modules, RAMs) that reflects spatial chromatin modularity. Enhancer-promoter interactions, loop anchors, super-enhancer clusters and extrachromosomal DNAs (ecDNAs) are found to occur more often within the same RAMs than within the same TADs. Consistently, compared to the TAD boundaries, deletions of RAM boundaries perturb the chromatin structure more severely (may even cause cell death) and somatic variants in cancer samples are more enriched in RAM boundaries. These observations suggest that RAMs reflect a modular organization of the 3D genome at a scale better aligned with chromatin activity, providing a bridge connecting the structural and functional modularity of the genome.
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18
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Comparison of the somatic TADs and lampbrush chromomere-loop complexes in transcriptionally active prophase I oocytes. Chromosoma 2022; 131:207-223. [PMID: 36031655 DOI: 10.1007/s00412-022-00780-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 07/26/2022] [Accepted: 08/01/2022] [Indexed: 11/03/2022]
Abstract
In diplotene oocyte nuclei of all vertebrate species, except mammals, chromosomes lack interchromosomal contacts and chromatin is linearly compartmentalized into distinct chromomere-loop complexes forming lampbrush chromosomes. However, the mechanisms underlying the formation of chromomere-loop complexes remain unexplored. Here we aimed to compare somatic topologically associating domains (TADs), recently identified in chicken embryonic fibroblasts, with chromomere-loop complexes in lampbrush meiotic chromosomes. By measuring 3D-distances and colocalization between linear equidistantly located genomic loci, positioned within one TAD or separated by a TAD border, we confirmed the presence of predicted TADs in chicken embryonic fibroblast nuclei. Using three-colored FISH with BAC probes, we mapped equidistant genomic regions included in several sequential somatic TADs on isolated chicken lampbrush chromosomes. Eight genomic regions, each comprising two or three somatic TADs, were mapped to non-overlapping neighboring lampbrush chromatin domains - lateral loops, chromomeres, or chromomere-loop complexes. Genomic loci from the neighboring somatic TADs could localize in one lampbrush chromomere-loop complex, while genomic loci belonging to the same somatic TAD could be localized in neighboring lampbrush chromomere-loop domains. In addition, FISH-mapping of BAC probes to the nascent transcripts on the lateral loops indicates transcription of at least 17 protein-coding genes and 2 non-coding RNA genes during the lampbrush stage of chicken oogenesis, including genes involved in oocyte maturation and early embryo development.
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19
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Conte M, Irani E, Chiariello AM, Abraham A, Bianco S, Esposito A, Nicodemi M. Loop-extrusion and polymer phase-separation can co-exist at the single-molecule level to shape chromatin folding. Nat Commun 2022; 13:4070. [PMID: 35831310 PMCID: PMC9279381 DOI: 10.1038/s41467-022-31856-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 07/06/2022] [Indexed: 11/09/2022] Open
Abstract
Loop-extrusion and phase-separation have been proposed as mechanisms that shape chromosome spatial organization. It is unclear, however, how they perform relative to each other in explaining chromatin architecture data and whether they compete or co-exist at the single-molecule level. Here, we compare models of polymer physics based on loop-extrusion and phase-separation, as well as models where both mechanisms act simultaneously in a single molecule, against multiplexed FISH data available in human loci in IMR90 and HCT116 cells. We find that the different models recapitulate bulk Hi-C and average multiplexed microscopy data. Single-molecule chromatin conformations are also well captured, especially by phase-separation based models that better reflect the experimentally reported segregation in globules of the considered genomic loci and their cell-to-cell structural variability. Such a variability is consistent with two main concurrent causes: single-cell epigenetic heterogeneity and an intrinsic thermodynamic conformational degeneracy of folding. Overall, the model combining loop-extrusion and polymer phase-separation provides a very good description of the data, particularly higher-order contacts, showing that the two mechanisms can co-exist in shaping chromatin architecture in single cells.
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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
| | - Ehsan Irani
- Berlin Institute for Medical Systems Biology, Max-Delbrück Centre (MDC) for Molecular Medicine, Berlin, Germany
- Berlin Institute of Health (BIH), MDC-Berlin, 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
| | - Alex Abraham
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126, Naples, Italy
| | - Simona Bianco
- Berlin Institute for Medical Systems Biology, Max-Delbrück Centre (MDC) for Molecular Medicine, Berlin, Germany
| | - Andrea Esposito
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, Complesso Universitario di Monte Sant'Angelo, 80126, Naples, Italy
| | - Mario Nicodemi
- 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.
- Berlin Institute of Health (BIH), MDC-Berlin, Berlin, Germany.
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20
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Lamberti WF, Zang C. Extracting physical characteristics of higher-order chromatin structures from 3D image data. Comput Struct Biotechnol J 2022; 20:3387-3398. [PMID: 35832633 PMCID: PMC9260447 DOI: 10.1016/j.csbj.2022.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/09/2022] [Accepted: 06/09/2022] [Indexed: 11/25/2022] Open
Abstract
Higher-order chromatin structures have functional impacts on gene regulation and cell identity determination. Using high-throughput sequencing (HTS)-based methods like Hi-C, active or inactive compartments and open or closed topologically associating domain (TAD) structures can be identified on a cell population level. Recently developed high-resolution three-dimensional (3D) molecular imaging techniques such as 3D electron microscopy with in situ hybridization (3D-EMSIH) and 3D structured illumination microscopy (3D-SIM) enable direct detection of physical representations of chromatin structures in a single cell. However, computational analysis of 3D image data with explainability and interpretability on functional characteristics of chromatin structures is still challenging. We developed Extracting Physical-Characteristics from Images of Chromatin Structures (EPICS), a machine-learning based computational method for processing high-resolution chromatin 3D image data. Using EPICS on images produced by 3D-EMISH or 3D-SIM techniques, we generated more direct 3D representations of higher-order chromatin structures, identified major chromatin domains, and determined the open or closed status of each domain. We identified several high-contributing features from the model as the major physical characteristics that define the open or closed chromatin domains, demonstrating the explainability and interpretability of EPICS. EPICS can be applied to the analysis of other high-resolution 3D molecular imaging data for spatial genomics studies. The R and Python codes of EPICS are available at https://github.com/zang-lab/epics.
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Affiliation(s)
- William Franz Lamberti
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA 22908, USA
| | - Chongzhi Zang
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA 22908, USA
- Department of Public Health Sciences, University of Virginia, Charlottesville, VA 22908, USA
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21
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Emerson DJ, Zhao PA, Cook AL, Barnett RJ, Klein KN, Saulebekova D, Ge C, Zhou L, Simandi Z, Minsk MK, Titus KR, Wang W, Gong W, Zhang D, Yang L, Venev SV, Gibcus JH, Yang H, Sasaki T, Kanemaki MT, Yue F, Dekker J, Chen CL, Gilbert DM, Phillips-Cremins JE. Cohesin-mediated loop anchors confine the locations of human replication origins. Nature 2022; 606:812-819. [PMID: 35676475 PMCID: PMC9217744 DOI: 10.1038/s41586-022-04803-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 04/26/2022] [Indexed: 12/18/2022]
Abstract
DNA replication occurs through an intricately regulated series of molecular events and is fundamental for genome stability1,2. At present, it is unknown how the locations of replication origins are determined in the human genome. Here we dissect the role of topologically associating domains (TADs)3-6, subTADs7 and loops8 in the positioning of replication initiation zones (IZs). We stratify TADs and subTADs by the presence of corner-dots indicative of loops and the orientation of CTCF motifs. We find that high-efficiency, early replicating IZs localize to boundaries between adjacent corner-dot TADs anchored by high-density arrays of divergently and convergently oriented CTCF motifs. By contrast, low-efficiency IZs localize to weaker dotless boundaries. Following ablation of cohesin-mediated loop extrusion during G1, high-efficiency IZs become diffuse and delocalized at boundaries with complex CTCF motif orientations. Moreover, G1 knockdown of the cohesin unloading factor WAPL results in gained long-range loops and narrowed localization of IZs at the same boundaries. Finally, targeted deletion or insertion of specific boundaries causes local replication timing shifts consistent with IZ loss or gain, respectively. Our data support a model in which cohesin-mediated loop extrusion and stalling at a subset of genetically encoded TAD and subTAD boundaries is an essential determinant of the locations of replication origins in human S phase.
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Affiliation(s)
- Daniel J Emerson
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Peiyao A Zhao
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Ashley L Cook
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - R Jordan Barnett
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kyle N Klein
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Dalila Saulebekova
- Institut Curie, PSL Research University, CNRS UMR3244, Dynamics of Genetic Information, Sorbonne Université, Paris, France
| | - Chunmin Ge
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Linda Zhou
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Zoltan Simandi
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Miriam K Minsk
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Katelyn R Titus
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Weitao Wang
- Institut Curie, PSL Research University, CNRS UMR3244, Dynamics of Genetic Information, Sorbonne Université, Paris, France
| | - Wanfeng Gong
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Di Zhang
- Children's Hospital of Pennsylvania, Philadelphia, PA, USA
| | - Liyan Yang
- University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Sergey V Venev
- University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Johan H Gibcus
- University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Hongbo Yang
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Takayo Sasaki
- San Diego Biomedical Research Institute, San Diego, CA, USA
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Japan
- Department of Genetics, The Graduate University for Advanced Studies (Sokendai), Mishima, Japan
| | - Feng Yue
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Job Dekker
- University of Massachusetts Chan Medical School, Worcester, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Chun-Long Chen
- Institut Curie, PSL Research University, CNRS UMR3244, Dynamics of Genetic Information, Sorbonne Université, Paris, France
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
- San Diego Biomedical Research Institute, San Diego, CA, USA
| | - Jennifer E Phillips-Cremins
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA.
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- New York Stem Cell Foundation Robertson Investigator, New York, NY, USA.
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22
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Super-resolution visualization of chromatin loop folding in human lymphoblastoid cells using interferometric photoactivated localization microscopy. Sci Rep 2022; 12:8582. [PMID: 35595799 PMCID: PMC9122977 DOI: 10.1038/s41598-022-12568-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/10/2022] [Indexed: 11/18/2022] Open
Abstract
The three-dimensional (3D) genome structure plays a fundamental role in gene regulation and cellular functions. Recent studies in 3D genomics inferred the very basic functional chromatin folding structures known as chromatin loops, the long-range chromatin interactions that are mediated by protein factors and dynamically extruded by cohesin. We combined the use of FISH staining of a very short (33 kb) chromatin fragment, interferometric photoactivated localization microscopy (iPALM), and traveling salesman problem-based heuristic loop reconstruction algorithm from an image of the one of the strongest CTCF-mediated chromatin loops in human lymphoblastoid cells. In total, we have generated thirteen good quality images of the target chromatin region with 2–22 nm oligo probe localization precision. We visualized the shape of the single chromatin loops with unprecedented genomic resolution which allowed us to study the structural heterogeneity of chromatin looping. We were able to compare the physical distance maps from all reconstructed image-driven computational models with contact frequencies observed by ChIA-PET and Hi-C genomic-driven methods to examine the concordance between single cell imaging and population based genomic data.
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23
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The Chromatin Architectural Protein CTCF Is Critical for Cell Survival upon Irradiation-Induced DNA Damage. Int J Mol Sci 2022; 23:ijms23073896. [PMID: 35409255 PMCID: PMC8999573 DOI: 10.3390/ijms23073896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/26/2022] [Accepted: 03/29/2022] [Indexed: 02/05/2023] Open
Abstract
CTCF is a nuclear protein initially discovered for its role in enhancer-promoter insulation. It has been shown to play a role in genome architecture and in fact, its DNA binding sites are enriched at the borders of chromatin domains. Recently, we showed that depletion of CTCF impairs the DNA damage response to ionizing radiation. To investigate the relationship between chromatin domains and DNA damage repair, we present here clonogenic survival assays in different cell lines upon CTCF knockdown and ionizing irradiation. The application of a wide range of ionizing irradiation doses (0–10 Gy) allowed us to investigate the survival response through a biophysical model that accounts for the double-strand breaks’ probability distribution onto chromatin domains. We demonstrate that the radiosensitivity of different cell lines is increased upon lowering the amount of the architectural protein. Our model shows that the deficiency in the DNA repair ability is related to the changes in the size of chromatin domains that occur when different amounts of CTCF are present in the nucleus.
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24
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Autophagy in mesenchymal progenitors protects mice against bone marrow failure after severe intermittent stress. Blood 2022; 139:690-703. [PMID: 34657154 PMCID: PMC8814682 DOI: 10.1182/blood.2021011775] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 10/01/2021] [Indexed: 11/26/2022] Open
Abstract
The cellular mechanisms required to ensure homeostasis of the hematopoietic niche and the ability of this niche to support hematopoiesis upon stress remain elusive. We here identify Wnt5a in Osterix+ mesenchymal progenitor and stem cells (MSPCs) as a critical factor for niche-dependent hematopoiesis. Mice lacking Wnt5a in MSPCs suffer from stress-related bone marrow (BM) failure and increased mortality. Niche cells devoid of Wnt5a show defective actin stress fiber orientation due to an elevated activity of the small GTPase CDC42. This results in incorrect positioning of autophagosomes and lysosomes, thus reducing autophagy and increasing oxidative stress. In MSPCs from patients from BM failure states which share features of peripheral cytopenia and hypocellular BM, we find similar defects in actin stress fiber orientation, reduced and incorrect colocalization of autophagosomes and lysosomes, and CDC42 activation. Strikingly, a short pharmacological intervention to attenuate elevated CDC42 activation in vivo in mice prevents defective actin-anchored autophagy in MSPCs, salvages hematopoiesis and protects against lethal cytopenia upon stress. In summary, our study identifies Wnt5a as a restriction factor for niche homeostasis by affecting CDC42-regulated actin stress-fiber orientation and autophagy upon stress. Our data further imply a critical role for autophagy in MSPCs for adequate support of hematopoiesis by the niche upon stress and in human diseases characterized by peripheral cytopenias and hypocellular BM.
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25
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Miura H, Hiratani I. Cell cycle dynamics and developmental dynamics of the 3D genome: toward linking the two timescales. Curr Opin Genet Dev 2022; 73:101898. [PMID: 35026526 DOI: 10.1016/j.gde.2021.101898] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/11/2021] [Accepted: 12/15/2021] [Indexed: 11/03/2022]
Abstract
In the mammalian cell nucleus, chromosomes are folded differently in interphase and mitosis. Interphase chromosomes are relatively decondensed and display at least two unique layers of higher-order organization: topologically associating domains (TADs) and cell-type-specific A/B compartments, which correlate well with early/late DNA replication timing (RT). In mitosis, these structures rapidly disappear but are gradually reconstructed during G1 phase, coincident with the establishment of the RT program. However, these structures also change dynamically during cell differentiation and reprogramming, and yet we are surprisingly ignorant about the relationship between their cell cycle dynamics and developmental dynamics. In this review, we summarize the recent findings on this topic, discuss how these two processes might be coordinated with each other and its potential significance.
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Affiliation(s)
- Hisashi Miura
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047 Japan
| | - Ichiro Hiratani
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047 Japan.
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26
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Boltsis I, Grosveld F, Giraud G, Kolovos P. Chromatin Conformation in Development and Disease. Front Cell Dev Biol 2021; 9:723859. [PMID: 34422840 PMCID: PMC8371409 DOI: 10.3389/fcell.2021.723859] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 07/16/2021] [Indexed: 01/23/2023] Open
Abstract
Chromatin domains and loops are important elements of chromatin structure and dynamics, but much remains to be learned about their exact biological role and nature. Topological associated domains and functional loops are key to gene expression and hold the answer to many questions regarding developmental decisions and diseases. Here, we discuss new findings, which have linked chromatin conformation with development, differentiation and diseases and hypothesized on various models while integrating all recent findings on how chromatin architecture affects gene expression during development, evolution and disease.
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Affiliation(s)
- Ilias Boltsis
- Department of Cell Biology, Erasmus Medical Centre, Rotterdam, Netherlands
| | - Frank Grosveld
- Department of Cell Biology, Erasmus Medical Centre, Rotterdam, Netherlands
| | - Guillaume Giraud
- Department of Cell Biology, Erasmus Medical Centre, Rotterdam, Netherlands
- Cancer Research Center of Lyon – INSERM U1052, Lyon, France
| | - Petros Kolovos
- Department of Molecular Biology and Genetics, Democritus University of Thrace, Alexandroupolis, Greece
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27
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Tallan A, Stanton BZ. Inducible Protein Degradation to Understand Genome Architecture. Biochemistry 2021; 60:2387-2396. [PMID: 34292716 DOI: 10.1021/acs.biochem.1c00306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We review exciting recent advances in protein degradation, with a focus on chromatin structure. In our analysis of the literature, we highlight studies of kinetic control of protein stability for cohesin, condensin, ATP-dependent chromatin remodeling, and pioneer transcription factors. With new connections emerging between chromatin remodeling and genome structure, we anticipate exciting developments at the intersection of these topics to be revealed in the coming years. Moreover, we pay special attention to the 20-year anniversary of PROTACs, with an overview of E3 ligase/target pairings and central questions that might lead to the next generation of PROTACs with an expanded scope and generality. While steady-state experimental measurements with constitutive genome editing are impactful, we highlight complementary approaches for rapid kinetic protein degradation to uncover early targeting functions and to understand the central determinants of genome structure-function relationships.
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Affiliation(s)
- Alexi Tallan
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Center for Childhood Cancer and Blood Diseases, 700 Children's Drive, Columbus, Ohio 43205, United States.,Molecular, Cellular, and Developmental Biology Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210, United States
| | - Benjamin Z Stanton
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Center for Childhood Cancer and Blood Diseases, 700 Children's Drive, Columbus, Ohio 43205, United States.,Molecular, Cellular, and Developmental Biology Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210, United States.,Department of Pediatrics, The Ohio State University College of Medicine, 370 West 9th Avenue, Columbus, Ohio 43210, United States.,Department of Biological Chemistry and Pharmacology, The Ohio State University College of Medicine, 370 West 9th Avenue, Columbus, Ohio 43210, United States
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28
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Abstract
Immediately following the discovery of the structure of DNA and the semi-conservative replication of the parental DNA sequence into two new DNA strands, it became apparent that DNA replication is organized in a temporal and spatial fashion during the S phase of the cell cycle, correlated with the large-scale organization of chromatin in the nucleus. After many decades of limited progress, technological advances in genomics, genome engineering, and imaging have finally positioned the field to tackle mechanisms underpinning the temporal and spatial regulation of DNA replication and the causal relationships between DNA replication and other features of large-scale chromosome structure and function. In this review, we discuss these major recent discoveries as well as expectations for the coming decade.
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Affiliation(s)
- Athanasios E Vouzas
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306, USA
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29
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Hao X, Parmar JJ, Lelandais B, Aristov A, Ouyang W, Weber C, Zimmer C. Super-resolution visualization and modeling of human chromosomal regions reveals cohesin-dependent loop structures. Genome Biol 2021; 22:150. [PMID: 33975635 PMCID: PMC8111965 DOI: 10.1186/s13059-021-02343-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 04/08/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The 3D organization of the chromatin fiber in cell nuclei plays a key role in the regulation of gene expression. Genome-wide techniques to score DNA-DNA contacts, such as Hi-C, reveal the partitioning of chromosomes into epigenetically defined active and repressed compartments and smaller "topologically associated" domains. These domains are often associated with chromatin loops, which largely disappear upon removal of cohesin. Because most Hi-C implementations average contact frequencies over millions of cells and do not provide direct spatial information, it remains unclear whether and how frequently chromatin domains and loops exist in single cells. RESULTS We combine 3D single-molecule localization microscopy with a low-cost fluorescence labeling strategy that does not denature the DNA, to visualize large portions of single human chromosomes in situ at high resolution. In parallel, we develop multi-scale, whole nucleus polymer simulations, that predict chromatin structures at scales ranging from 5 kb up to entire chromosomes. We image chromosomes in G1 and M phase and examine the effect of cohesin on interphase chromatin structure. Depletion of cohesin leads to increased prevalence of loose chromatin stretches, increased gyration radii, and reduced smoothness of imaged chromatin regions. By comparison to model predictions, we estimate that 6-25 or more purely cohesin-dependent chromatin loops coexist per megabase of DNA in single cells, suggesting that the vast majority of the genome is enclosed in loops. CONCLUSION Our results provide new constraints on chromatin structure and showcase an affordable non-invasive approach to study genome organization in single cells.
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Affiliation(s)
- Xian Hao
- Institut Pasteur, Imaging and Modeling Unit, UMR 3691, CNRS, Paris, France
- School of Public Health & Jiangxi Provincial Key Laboratory of Preventive Medicine, Nanchang University, Nanchang, 330006, China
| | - Jyotsana J Parmar
- Institut Pasteur, Imaging and Modeling Unit, UMR 3691, CNRS, Paris, France
- Simons Center for the Study of Living Machines, National Center for Biological Sciences (TIFR), Bangalore, Karnataka, 560065, India
| | - Benoît Lelandais
- Institut Pasteur, Imaging and Modeling Unit, UMR 3691, CNRS, Paris, France
| | - Andrey Aristov
- Institut Pasteur, Imaging and Modeling Unit, UMR 3691, CNRS, Paris, France
| | - Wei Ouyang
- Institut Pasteur, Imaging and Modeling Unit, UMR 3691, CNRS, Paris, France
- Université de Paris, F-75013, Paris, France
| | - Christian Weber
- Institut Pasteur, Imaging and Modeling Unit, UMR 3691, CNRS, Paris, France
| | - Christophe Zimmer
- Institut Pasteur, Imaging and Modeling Unit, UMR 3691, CNRS, Paris, France.
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30
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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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