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Manning SA, Kroeger B, Deng Q, Brooks E, Fonseka Y, Hinde E, Harvey KF. The Drosophila Hippo pathway transcription factor Scalloped and its co-factors alter each other's chromatin binding dynamics and transcription in vivo. Dev Cell 2024; 59:1640-1654.e5. [PMID: 38670104 DOI: 10.1016/j.devcel.2024.04.006] [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: 09/12/2022] [Revised: 02/12/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024]
Abstract
The Hippo pathway is an important regulator of organ growth and cell fate. The major mechanism by which Hippo is known to control transcription is by dictating the nucleo-cytoplasmic shuttling rate of Yorkie, a transcription co-activator, which promotes transcription with the DNA binding protein Scalloped. The nuclear biophysical behavior of Yorkie and Scalloped, and whether this is regulated by the Hippo pathway, remains unexplored. Using multiple live-imaging modalities on Drosophila tissues, we found that Scalloped interacts with DNA on a broad range of timescales, and enrichment of Scalloped at sites of active transcription is mediated by longer DNA dwell times. Further, Yorkie increased Scalloped's DNA dwell time, whereas the repressors Nervous fingers 1 (Nerfin-1) and Tondu-domain-containing growth inhibitor (Tgi) decreased it. Therefore, the Hippo pathway influences transcription not only by controlling nuclear abundance of Yorkie but also by modifying the DNA binding kinetics of the transcription factor Scalloped.
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Affiliation(s)
- Samuel A Manning
- Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia; Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
| | - Benjamin Kroeger
- Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia; Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
| | - Qiji Deng
- Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
| | - Elliot Brooks
- Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia; Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
| | - Yoshana Fonseka
- Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia
| | - Elizabeth Hinde
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia; Department of Biochemistry and Pharmacology, Bio21 Institute, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Kieran F Harvey
- Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia; Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC 3010, Australia.
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2
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Shim AR, Frederick J, Pujadas EM, Kuo T, Ye IC, Pritchard JA, Dunton CL, Gonzalez PC, Acosta N, Jain S, Anthony NM, Almassalha LM, Szleifer I, Backman V. Formamide denaturation of double-stranded DNA for fluorescence in situ hybridization (FISH) distorts nanoscale chromatin structure. PLoS One 2024; 19:e0301000. [PMID: 38805476 PMCID: PMC11132451 DOI: 10.1371/journal.pone.0301000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 03/10/2024] [Indexed: 05/30/2024] Open
Abstract
As imaging techniques rapidly evolve to probe nanoscale genome organization at higher resolution, it is critical to consider how the reagents and procedures involved in sample preparation affect chromatin at the relevant length scales. Here, we investigate the effects of fluorescent labeling of DNA sequences within chromatin using the gold standard technique of three-dimensional fluorescence in situ hybridization (3D FISH). The chemical reagents involved in the 3D FISH protocol, specifically formamide, cause significant alterations to the sub-200 nm (sub-Mbp) chromatin structure. Alternatively, two labeling methods that do not rely on formamide denaturation, resolution after single-strand exonuclease resection (RASER)-FISH and clustered regularly interspaced short palindromic repeats (CRISPR)-Sirius, had minimal impact on the three-dimensional organization of chromatin. We present a polymer physics-based analysis of these protocols with guidelines for their interpretation when assessing chromatin structure using currently available techniques.
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Affiliation(s)
- Anne R. Shim
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Jane Frederick
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Emily M. Pujadas
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Tiffany Kuo
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - I. Chae Ye
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Joshua A. Pritchard
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Cody L. Dunton
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Paola Carrillo Gonzalez
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Nicolas Acosta
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Surbhi Jain
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Nicholas M. Anthony
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Luay M. Almassalha
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
- Department of Gastroenterology and Hepatology, Northwestern Memorial Hospital, Chicago, Illinois, United States of America
| | - Igal Szleifer
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Chemistry, Northwestern University, Evanston, Illinois, United States of America
| | - Vadim Backman
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
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3
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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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4
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Zülske T, Attou A, Groß L, Hörl D, Harz H, Wedemann G. Nucleosome spacing controls chromatin spatial structure and accessibility. Biophys J 2024; 123:847-857. [PMID: 38419332 PMCID: PMC10995425 DOI: 10.1016/j.bpj.2024.02.024] [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: 09/15/2023] [Revised: 01/31/2024] [Accepted: 02/26/2024] [Indexed: 03/02/2024] Open
Abstract
Recent research highlights the significance of the three-dimensional structure of chromatin in regulating various cellular processes, particularly transcription. This is achieved through dynamic chromatin structures that facilitate long-range contacts and control spatial accessibility. Chromatin consists of DNA and a variety of proteins, of which histones play an essential structural role by forming nucleosomes. Extensive experimental and theoretical research in recent decades has yielded conflicting results about key factors that regulate the spatial structure of chromatin, which remains enigmatic. By using a computer model that allows us to simulate chromatin volumes containing physiological nucleosome concentrations, we investigated whether nucleosome spacing or nucleosome density is fundamental for three-dimensional chromatin accessibility. Unexpectedly, the regularity of the nucleosome spacing is crucial for determining the accessibility of the chromatin network to diffusive processes, whereas variation in nucleosome concentrations has only minor effects. Using only the basic physical properties of DNA and nucleosomes was sufficient to generate chromatin structures consistent with published electron microscopy data. Contrary to other work, we found that nucleosome density did not substantially alter the properties of chromatin fibers or contact probabilities of genomic loci. No breakup of fiber-like structures was observed at high molar density. These findings challenge previous assumptions and highlight the importance of nucleosome spacing as a key driver of chromatin organization. These results identified changes in nucleosome spacing as a tentative mechanism for altering the spatial chromatin structure and thus genomic functions.
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Affiliation(s)
- Tilo Zülske
- Competence Center Bioinformatics, Institute for Applied Computer Science, Hochschule Stralsund, Stralsund, Germany
| | - Aymen Attou
- Competence Center Bioinformatics, Institute for Applied Computer Science, Hochschule Stralsund, Stralsund, Germany; Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Laurens Groß
- Competence Center Bioinformatics, Institute for Applied Computer Science, Hochschule Stralsund, Stralsund, Germany
| | - David Hörl
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Hartmann Harz
- Human Biology & BioImaging, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Gero Wedemann
- Competence Center Bioinformatics, Institute for Applied Computer Science, Hochschule Stralsund, Stralsund, Germany.
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5
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Seckler H, Metzler R, Kelty-Stephen DG, Mangalam M. Multifractal spectral features enhance classification of anomalous diffusion. Phys Rev E 2024; 109:044133. [PMID: 38755826 DOI: 10.1103/physreve.109.044133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 03/19/2024] [Indexed: 05/18/2024]
Abstract
Anomalous diffusion processes, characterized by their nonstandard scaling of the mean-squared displacement, pose a unique challenge in classification and characterization. In a previous study [Mangalam et al., Phys. Rev. Res. 5, 023144 (2023)2643-156410.1103/PhysRevResearch.5.023144], we established a comprehensive framework for understanding anomalous diffusion using multifractal formalism. The present study delves into the potential of multifractal spectral features for effectively distinguishing anomalous diffusion trajectories from five widely used models: fractional Brownian motion, scaled Brownian motion, continuous-time random walk, annealed transient time motion, and Lévy walk. We generate extensive datasets comprising 10^{6} trajectories from these five anomalous diffusion models and extract multiple multifractal spectra from each trajectory to accomplish this. Our investigation entails a thorough analysis of neural network performance, encompassing features derived from varying numbers of spectra. We also explore the integration of multifractal spectra into traditional feature datasets, enabling us to assess their impact comprehensively. To ensure a statistically meaningful comparison, we categorize features into concept groups and train neural networks using features from each designated group. Notably, several feature groups demonstrate similar levels of accuracy, with the highest performance observed in groups utilizing moving-window characteristics and p varation features. Multifractal spectral features, particularly those derived from three spectra involving different timescales and cutoffs, closely follow, highlighting their robust discriminatory potential. Remarkably, a neural network exclusively trained on features from a single multifractal spectrum exhibits commendable performance, surpassing other feature groups. In summary, our findings underscore the diverse and potent efficacy of multifractal spectral features in enhancing the predictive capacity of machine learning to classify anomalous diffusion processes.
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Affiliation(s)
- Henrik Seckler
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Ralf Metzler
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
- Asia Pacific Center for Theoretical Physics, Pohang 37673, Republic of Korea
| | - Damian G Kelty-Stephen
- Department of Psychology, State University of New York at New Paltz, New Paltz, New York 12561, USA
| | - Madhur Mangalam
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, Omaha, Nebraska 68182, USA
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6
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Guillaumin S, Gurdal M, Zeugolis DI. Gums as Macromolecular Crowding Agents in Human Skin Fibroblast Cultures. Life (Basel) 2024; 14:435. [PMID: 38672707 PMCID: PMC11051389 DOI: 10.3390/life14040435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/10/2024] [Accepted: 03/19/2024] [Indexed: 04/28/2024] Open
Abstract
Even though tissue-engineered medicines are under intense academic, clinical, and commercial investigation, only a handful of products have been commercialised, primarily due to the costs associated with their prolonged manufacturing. While macromolecular crowding has been shown to enhance and accelerate extracellular matrix deposition in eukaryotic cell culture, possibly offering a solution in this procrastinating tissue-engineered medicine development, there is still no widely accepted macromolecular crowding agent. With these in mind, we herein assessed the potential of gum Arabic, gum gellan, gum karaya, and gum xanthan as macromolecular crowding agents in WS1 skin fibroblast cultures (no macromolecular crowding and carrageenan were used as a control). Dynamic light scattering analysis revealed that all macromolecules had negative charge and were polydispersed. None of the macromolecules affected basic cellular function. At day 7 (the longest time point assessed), gel electrophoresis analysis revealed that all macromolecules significantly increased collagen type I deposition in comparison to the non-macromolecular crowding group. Also at day 7, immunofluorescence analysis revealed that carrageenan; the 50 µg/mL, 75 µg/mL, and 100 µg/mL gum gellan; and the 500 µg/mL and 1000 µg/mL gum xanthan significantly increased both collagen type I and collagen type III deposition and only carrageenan significantly increased collagen type V deposition, all in comparison to the non-macromolecular crowding group at the respective time point. This preliminary study demonstrates the potential of gums as macromolecular crowding agents, but more detailed biological studies are needed to fully exploit their potential in the development of tissue-engineered medicines.
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Affiliation(s)
- Salome Guillaumin
- Regenerative, Modular & Developmental Engineering Laboratory (REMODEL) and Science Foundation Ireland (SFI) Centre for Research in Medical Devices (CÚRAM), Biomedical Sciences Building, University of Galway, H91 TK33 Galway, Ireland; (S.G.); (M.G.)
| | - Mehmet Gurdal
- Regenerative, Modular & Developmental Engineering Laboratory (REMODEL) and Science Foundation Ireland (SFI) Centre for Research in Medical Devices (CÚRAM), Biomedical Sciences Building, University of Galway, H91 TK33 Galway, Ireland; (S.G.); (M.G.)
- Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Charles Institute of Dermatology, Conway Institute of Biomolecular & Biomedical Research and School of Mechanical & Materials Engineering, University College Dublin (UCD), D04 V1W8 Dublin, Ireland
| | - Dimitrios I. Zeugolis
- Regenerative, Modular & Developmental Engineering Laboratory (REMODEL) and Science Foundation Ireland (SFI) Centre for Research in Medical Devices (CÚRAM), Biomedical Sciences Building, University of Galway, H91 TK33 Galway, Ireland; (S.G.); (M.G.)
- Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Charles Institute of Dermatology, Conway Institute of Biomolecular & Biomedical Research and School of Mechanical & Materials Engineering, University College Dublin (UCD), D04 V1W8 Dublin, Ireland
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7
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Singh A, Chakrabarti S. Diffusion controls local versus dispersed inheritance of histones during replication and shapes epigenomic architecture. PLoS Comput Biol 2023; 19:e1011725. [PMID: 38109423 PMCID: PMC10760866 DOI: 10.1371/journal.pcbi.1011725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 01/02/2024] [Accepted: 12/01/2023] [Indexed: 12/20/2023] Open
Abstract
The dynamics of inheritance of histones and their associated modifications across cell divisions can have major consequences on maintenance of the cellular epigenomic state. Recent experiments contradict the long-held notion that histone inheritance during replication is always local, suggesting that active and repressed regions of the genome exhibit fundamentally different histone dynamics independent of transcription-coupled turnover. Here we develop a stochastic model of histone dynamics at the replication fork and demonstrate that differential diffusivity of histones in active versus repressed chromatin is sufficient to quantitatively explain these recent experiments. Further, we use the model to predict patterns in histone mark similarity between pairs of genomic loci that should be developed as a result of diffusion, but cannot originate from either PRC2 mediated mark spreading or transcriptional processes. Interestingly, using a combination of CHIP-seq, replication timing and Hi-C datasets we demonstrate that all the computationally predicted patterns are consistently observed for both active and repressive histone marks in two different cell lines. While direct evidence for histone diffusion remains controversial, our results suggest that dislodged histones in euchromatin and facultative heterochromatin may exhibit some level of diffusion within "Diffusion-Accessible-Domains" (DADs), leading to redistribution of epigenetic marks within and across chromosomes. Preservation of the epigenomic state across cell divisions therefore might be achieved not by passing on strict positional information of histone marks, but by maintaining the marks in somewhat larger DADs of the genome.
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Affiliation(s)
- Archit Singh
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Shaon Chakrabarti
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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8
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Smirnov E, Molínová P, Chmúrčiaková N, Vacík T, Cmarko D. Non-canonical DNA structures in the human ribosomal DNA. Histochem Cell Biol 2023; 160:499-515. [PMID: 37750997 DOI: 10.1007/s00418-023-02233-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2023] [Indexed: 09/27/2023]
Abstract
Non-canonical structures (NCS) refer to the various forms of DNA that differ from the B-conformation described by Watson and Crick. It has been found that these structures are usual components of the genome, actively participating in its essential functions. The present review is focused on the nine kinds of NCS appearing or likely to appear in human ribosomal DNA (rDNA): supercoiling structures, R-loops, G-quadruplexes, i-motifs, DNA triplexes, cruciform structures, DNA bubbles, and A and Z DNA conformations. We discuss the conditions of their generation, including their sequence specificity, distribution within the locus, dynamics, and beneficial and detrimental role in the cell.
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Affiliation(s)
- Evgeny Smirnov
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic.
| | - Pavla Molínová
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Nikola Chmúrčiaková
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Tomáš Vacík
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Dušan Cmarko
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
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9
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Owen JA, Osmanović D, Mirny L. Design principles of 3D epigenetic memory systems. Science 2023; 382:eadg3053. [PMID: 37972190 PMCID: PMC11075759 DOI: 10.1126/science.adg3053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 09/28/2023] [Indexed: 11/19/2023]
Abstract
Cells remember their identities, in part, by using epigenetic marks-chemical modifications placed along the genome. How can mark patterns remain stable over cell generations despite their constant erosion by replication and other processes? We developed a theoretical model that reveals that three-dimensional (3D) genome organization can stabilize epigenetic memory as long as (i) there is a large density difference between chromatin compartments, (ii) modifying "reader-writer" enzymes spread marks in three dimensions, and (iii) the enzymes are limited in abundance relative to their histone substrates. Analogous to an associative memory that encodes memory in neuronal connectivity, mark patterns are encoded in a 3D network of chromosomal contacts. Our model provides a unified account of diverse observations and reveals a key role of 3D genome organization in epigenetic memory.
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Affiliation(s)
- Jeremy A. Owen
- Department of Physics, Massachusetts Institute of Technology; Cambridge, USA
| | - Dino Osmanović
- Department of Mechanical and Aeronautical Engineering, UCLA; Los Angeles, USA
| | - Leonid Mirny
- Department of Physics, Massachusetts Institute of Technology; Cambridge, USA
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10
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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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11
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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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12
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Wu K, Dhillon N, Bajor A, Abrahamson S, Kamakaka RT. Yeast Heterochromatin Only Stably Silences Weak Regulatory Elements by Altering Burst Duration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.05.561072. [PMID: 37873261 PMCID: PMC10592971 DOI: 10.1101/2023.10.05.561072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The interplay between nucleosomes and transcription factors leads to programs of gene expression. Transcriptional silencing involves the generation of a chromatin state that represses transcription and is faithfully propagated through DNA replication and cell division. Using multiple reporter assays, including directly visualizing transcription in single cells, we investigated a diverse set of UAS enhancers and core promoters for their susceptibility to heterochromatic gene silencing. These results show that heterochromatin only stably silences weak and stress induced regulatory elements but is unable to stably repress housekeeping gene regulatory elements and the partial repression did not result in bistable expression states. Permutation analysis of different UAS enhancers and core promoters indicate that both elements function together to determine the susceptibility of regulatory sequences to repression. Specific histone modifiers and chromatin remodellers function in an enhancer specific manner to aid these elements to resist repression suggesting that Sir proteins likely function in part by reducing nucleosome mobility. We also show that the strong housekeeping regulatory elements can be repressed if silencer bound Sir1 is increased, suggesting that Sir1 is a limiting component in silencing. Together, our data suggest that the heterochromatic locus has been optimized to stably silence the weak mating type gene regulatory elements but not strong housekeeping gene regulatory sequences which could help explain why these genes are often found at the boundaries of silenced domains.
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Affiliation(s)
- Kenneth Wu
- Department of MCD Biology, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Namrita Dhillon
- Department of MCD Biology, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Antone Bajor
- Electrical Engineering Department, Baskin School of Engineering, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Sara Abrahamson
- Electrical Engineering Department, Baskin School of Engineering, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
| | - Rohinton T. Kamakaka
- Department of MCD Biology, 1156 High Street, University of California, Santa Cruz, CA 95064 USA
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13
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Fournier M, Leclerc P, Leray A, Champelovier D, Agbazahou F, Dahmani F, Bidaux G, Furlan A, Héliot L. Combined SPT and FCS methods reveal a mechanism of RNAP II oversampling in cell nuclei. Sci Rep 2023; 13:14633. [PMID: 37669988 PMCID: PMC10480184 DOI: 10.1038/s41598-023-38668-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 07/12/2023] [Indexed: 09/07/2023] Open
Abstract
Gene expression orchestration is a key question in fundamental and applied research. Different models for transcription regulation were proposed, yet the dynamic regulation of RNA polymerase II (RNAP II) activity remains a matter of debate. To improve our knowledge of this topic, we investigated RNAP II motility in eukaryotic cells by combining single particle tracking (SPT) and fluorescence correlation spectroscopy (FCS) techniques, to take advantage of their different sensitivities in order to analyze together slow and fast molecular movements. Thanks to calibrated samples, we developed a benchmark for quantitative analysis of molecular dynamics, to eliminate the main potential instrumental biases. We applied this workflow to study the diffusion of RPB1, the catalytic subunit of RNAP II. By a cross-analysis of FCS and SPT, we could highlight different RPB1 motility states and identifyed a stationary state, a slow diffusion state, and two different modes of subdiffusion. Interestingly, our analysis also unveiled the oversampling by RPB1 of nuclear subdomains. Based on these data, we propose a novel model of spatio-temporal transcription regulation. Altogether, our results highlight the importance of combining microscopy approaches at different time scales to get a full insight into the real complexity of molecular kinetics in cells.
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Affiliation(s)
- Marie Fournier
- Univ. Lille, CNRS, UMR 8523, PhLAM Laboratoire de Physique des Lasers, Atomes et Molécules, Lille, France
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France
| | - Pierre Leclerc
- Univ. Lille, CNRS, UMR 8523, PhLAM Laboratoire de Physique des Lasers, Atomes et Molécules, Lille, France
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France
| | - Aymeric Leray
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Université de Bourgogne Franche Comte, Dijon, France
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France
| | - Dorian Champelovier
- Univ. Lille, CNRS, UMR 8523, PhLAM Laboratoire de Physique des Lasers, Atomes et Molécules, Lille, France
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France
| | - Florence Agbazahou
- Univ. Lille, CNRS, UMR 8523, PhLAM Laboratoire de Physique des Lasers, Atomes et Molécules, Lille, France
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France
| | - Fatima Dahmani
- Univ. Lille, CNRS, UMR 8523, PhLAM Laboratoire de Physique des Lasers, Atomes et Molécules, Lille, France
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France
| | - Gabriel Bidaux
- INSERM UMR 1060, CarMeN Laboratory, IHU OPERA, Hôpital Louis Pradel, Hospices Civils de Lyon, Univ Lyon1, Lyon, France
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France
| | - Alessandro Furlan
- Univ. Lille, CNRS, UMR 8523, PhLAM Laboratoire de Physique des Lasers, Atomes et Molécules, Lille, France.
- Univ. Lille, CNRS, Inserm, CHU Lille, UMR9020-U1277 -CANTHER -Cancer Heterogeneity Plasticity and Resistance to Therapies, Lille, 59000, France.
- Unité Tumorigenèse et Résistance aux Traitements, Centre Oscar Lambret, 59000, Lille, France.
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France.
| | - Laurent Héliot
- Univ. Lille, CNRS, UMR 8523, PhLAM Laboratoire de Physique des Lasers, Atomes et Molécules, Lille, France.
- CNRS, Groupement de Recherche ImaBio, 59655, Villeneuve d'Ascq, France.
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14
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Hertzog M, Erdel F. The Material Properties of the Cell Nucleus: A Matter of Scale. Cells 2023; 12:1958. [PMID: 37566037 PMCID: PMC10416959 DOI: 10.3390/cells12151958] [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: 06/30/2023] [Revised: 07/26/2023] [Accepted: 07/26/2023] [Indexed: 08/12/2023] Open
Abstract
Chromatin regulatory processes physically take place in the environment of the cell nucleus, which is filled with the chromosomes and a plethora of smaller biomolecules. The nucleus contains macromolecular assemblies of different sizes, from nanometer-sized protein complexes to micrometer-sized biomolecular condensates, chromosome territories, and nuclear bodies. This multiscale organization impacts the transport processes within the nuclear interior, the global mechanical properties of the nucleus, and the way the nucleus senses and reacts to mechanical stimuli. Here, we discuss recent work on these aspects, including microrheology and micromanipulation experiments assessing the material properties of the nucleus and its subcomponents. We summarize how the properties of multiscale media depend on the time and length scales probed in the experiment, and we reconcile seemingly contradictory observations made on different scales. We also revisit the concept of liquid-like and solid-like material properties for complex media such as the nucleus. We propose that the nucleus can be considered a multiscale viscoelastic medium composed of three major components with distinct properties: the lamina, the chromatin network, and the nucleoplasmic fluid. This multicomponent organization enables the nucleus to serve its different functions as a reaction medium on the nanoscale and as a mechanosensor and structural scaffold on the microscale.
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Affiliation(s)
| | - Fabian Erdel
- MCD, Center for Integrative Biology (CBI), University of Toulouse, CNRS, 169 Avenue Marianne Grunberg-Manago, 31062 Toulouse, France
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15
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D’Augustin O, Gaudon V, Siberchicot C, Smith R, Chapuis C, Depagne J, Veaute X, Busso D, Di Guilmi AM, Castaing B, Radicella JP, Campalans A, Huet S. Identification of key residues of the DNA glycosylase OGG1 controlling efficient DNA sampling and recruitment to oxidized bases in living cells. Nucleic Acids Res 2023; 51:4942-4958. [PMID: 37021552 PMCID: PMC10250219 DOI: 10.1093/nar/gkad243] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 02/28/2023] [Accepted: 03/24/2023] [Indexed: 04/07/2023] Open
Abstract
The DNA-glycosylase OGG1 oversees the detection and clearance of the 7,8-dihydro-8-oxoguanine (8-oxoG), which is the most frequent form of oxidized base in the genome. This lesion is deeply buried within the double-helix and its detection requires careful inspection of the bases by OGG1 via a mechanism that remains only partially understood. By analyzing OGG1 dynamics in the nucleus of living human cells, we demonstrate that the glycosylase constantly samples the DNA by rapidly alternating between diffusion within the nucleoplasm and short transits on the DNA. This sampling process, that we find to be tightly regulated by the conserved residue G245, is crucial for the rapid recruitment of OGG1 at oxidative lesions induced by laser micro-irradiation. Furthermore, we show that residues Y203, N149 and N150, while being all involved in early stages of 8-oxoG probing by OGG1 based on previous structural data, differentially regulate the sampling of the DNA and recruitment to oxidative lesions.
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Affiliation(s)
- Ostiane D’Augustin
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, F-35000 Rennes, France
- Université de Paris-Cité, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
| | | | - Capucine Siberchicot
- Université de Paris-Cité, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
| | - Rebecca Smith
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, F-35000 Rennes, France
| | - Catherine Chapuis
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, F-35000 Rennes, France
| | - Jordane Depagne
- Université de Paris-Cité, Inserm, CEA/IBFJ/IRCM/CIGEx, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- Université Paris-Saclay, Inserm, CEA/IBFJ/IRCM/CIGEx, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
| | - Xavier Veaute
- Université de Paris-Cité, Inserm, CEA/IBFJ/IRCM/CIGEx, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- Université Paris-Saclay, Inserm, CEA/IBFJ/IRCM/CIGEx, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
| | - Didier Busso
- Université de Paris-Cité, Inserm, CEA/IBFJ/IRCM/CIGEx, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- Université Paris-Saclay, Inserm, CEA/IBFJ/IRCM/CIGEx, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
| | - Anne-Marie Di Guilmi
- Université de Paris-Cité, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
| | | | - J Pablo Radicella
- Université de Paris-Cité, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
| | - Anna Campalans
- Université de Paris-Cité, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, CEA/IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
| | - Sébastien Huet
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, F-35000 Rennes, France
- Institut Universitaire de France, Paris, France
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16
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Dai S, Liu S, Zhou C, Yu F, Zhu G, Zhang W, Deng H, Burlingame A, Yu W, Wang T, Li N. Capturing the hierarchically assorted modules of protein-protein interactions in the organized nucleome. MOLECULAR PLANT 2023; 16:930-961. [PMID: 36960533 DOI: 10.1016/j.molp.2023.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 02/16/2023] [Accepted: 03/21/2023] [Indexed: 05/04/2023]
Abstract
Nuclear proteins are major constituents and key regulators of nucleome topological organization and manipulators of nuclear events. To decipher the global connectivity of nuclear proteins and the hierarchically organized modules of their interactions, we conducted two rounds of cross-linking mass spectrometry (XL-MS) analysis, one of which followed a quantitative double chemical cross-linking mass spectrometry (in vivoqXL-MS) workflow, and identified 24,140 unique crosslinks in total from the nuclei of soybean seedlings. This in vivo quantitative interactomics enabled the identification of 5340 crosslinks that can be converted into 1297 nuclear protein-protein interactions (PPIs), 1220 (94%) of which were non-confirmative (or novel) nuclear PPIs compared with those in repositories. There were 250 and 26 novel interactors of histones and the nucleolar box C/D small nucleolar ribonucleoprotein complex, respectively. Modulomic analysis of orthologous Arabidopsis PPIs produced 27 and 24 master nuclear PPI modules (NPIMs) that contain the condensate-forming protein(s) and the intrinsically disordered region-containing proteins, respectively. These NPIMs successfully captured previously reported nuclear protein complexes and nuclear bodies in the nucleus. Surprisingly, these NPIMs were hierarchically assorted into four higher-order communities in a nucleomic graph, including genome and nucleolus communities. This combinatorial pipeline of 4C quantitative interactomics and PPI network modularization revealed 17 ethylene-specific module variants that participate in a broad range of nuclear events. The pipeline was able to capture both nuclear protein complexes and nuclear bodies, construct the topological architectures of PPI modules and module variants in the nucleome, and probably map the protein compositions of biomolecular condensates.
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Affiliation(s)
- Shuaijian Dai
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Shichang Liu
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Chen Zhou
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Fengchao Yu
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Guang Zhu
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Wenhao Zhang
- Tsinghua-Peking Joint Centre for Life Sciences, Centre for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Haiteng Deng
- Tsinghua-Peking Joint Centre for Life Sciences, Centre for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Al Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Weichuan Yu
- The HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute, Futian, Shenzhen, Guangdong 518057, China; Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
| | - Tingliang Wang
- Tsinghua-Peking Joint Centre for Life Sciences, Centre for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
| | - Ning Li
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China; Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong, China; The HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute, Futian, Shenzhen, Guangdong 518057, China.
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17
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Kim T, Yoo J, Do S, Hwang DS, Park Y, Shin Y. RNA-mediated demixing transition of low-density condensates. Nat Commun 2023; 14:2425. [PMID: 37105967 PMCID: PMC10140143 DOI: 10.1038/s41467-023-38118-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
Biomolecular condensates play a key role in organizing cellular reactions by concentrating a specific set of biomolecules. However, whether condensate formation is accompanied by an increase in the total mass concentration within condensates or by the demixing of already highly crowded intracellular components remains elusive. Here, using refractive index imaging, we quantify the mass density of several condensates, including nucleoli, heterochromatin, nuclear speckles, and stress granules. Surprisingly, the latter two condensates exhibit low densities with a total mass concentration similar to the surrounding cyto- or nucleoplasm. Low-density condensates display higher permeability to cellular protein probes. We find that RNA tunes the biomolecular density of condensates. Moreover, intracellular structures such as mitochondria heavily influence the way phase separation proceeds, impacting the localization, morphology, and growth of condensates. These findings favor a model where segregative phase separation driven by non-associative or repulsive molecular interactions together with RNA-mediated selective association of specific components can give rise to low-density condensates in the crowded cellular environment.
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Affiliation(s)
- Taehyun Kim
- Department of Mechanical Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jaeyoon Yoo
- Department of Mechanical Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sungho Do
- Department of Mechanical Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Dong Soo Hwang
- Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - YongKeun Park
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- KAIST Institute for Health Science and Technology, Daejeon, 34141, Republic of Korea
- Tomocube Inc, Daejeon, 34109, South Korea
| | - Yongdae Shin
- Department of Mechanical Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, 08826, Korea.
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18
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Dupont C, Chahar D, Trullo A, Gostan T, Surcis C, Grimaud C, Fisher D, Feil R, Llères D. Evidence for low nanocompaction of heterochromatin in living embryonic stem cells. EMBO J 2023:e110286. [PMID: 37082862 DOI: 10.15252/embj.2021110286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/22/2023] [Accepted: 03/29/2023] [Indexed: 04/22/2023] Open
Abstract
Despite advances in the identification of chromatin regulators and genome interactions, the principles of higher-order chromatin structure have remained elusive. Here, we applied FLIM-FRET microscopy to analyse, in living cells, the spatial organisation of nanometre range proximity between nucleosomes, which we called "nanocompaction." Both in naive embryonic stem cells (ESCs) and in ESC-derived epiblast-like cells (EpiLCs), we find that, contrary to expectations, constitutive heterochromatin is much less compacted than bulk chromatin. The opposite was observed in fixed cells. HP1α knockdown increased nanocompaction in living ESCs, but this was overridden by loss of HP1β, indicating the existence of a dynamic HP1-dependent low compaction state in pluripotent cells. Depletion of H4K20me2/3 abrogated nanocompaction, while increased H4K20me3 levels accompanied the nuclear reorganisation during EpiLCs induction. Finally, the knockout of the nuclear cellular-proliferation marker Ki-67 strongly reduced both interphase and mitotic heterochromatin nanocompaction in ESCs. Our data indicate that, contrary to prevailing models, heterochromatin is not highly compacted at the nanoscale but resides in a dynamic low nanocompaction state that depends on H4K20me2/3, the balance between HP1 isoforms, and Ki-67.
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Affiliation(s)
- Claire Dupont
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
| | - Dhanvantri Chahar
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
| | - Antonio Trullo
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
| | - Thierry Gostan
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
| | - Caroline Surcis
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
| | - Charlotte Grimaud
- Institute of Human Genetics (IGH), CNRS, University of Montpellier, Montpellier, France
| | - Daniel Fisher
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
| | - Robert Feil
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
| | - David Llères
- Institute of Molecular Genetics of Montpellier (IGMM), CNRS, University of Montpellier, Montpellier, France
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19
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Muromachi K, Nakano R, Fujita-Yoshigaki J, Sugiya H, Tani-Ishii N. BMP-1-induced GBA1 nuclear accumulation provokes CCN2 mRNA expression via importin-β-mediated nucleocytoplasmic pathway. J Cell Commun Signal 2023:10.1007/s12079-023-00740-3. [DOI: 10.1007/s12079-023-00740-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 03/13/2023] [Indexed: 03/29/2023] Open
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20
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Consistencies and contradictions in different polymer models of chromatin architecture. Comput Struct Biotechnol J 2023; 21:1084-1091. [PMID: 36789261 PMCID: PMC9900451 DOI: 10.1016/j.csbj.2023.01.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 01/26/2023] Open
Abstract
Genetic information is stored in very long DNA molecules, which are folded to form chromatin, a similarly long polymer fibre that is ultimately organised into chromosomes. The organisation of chromatin is fundamental to many cellular functions, from the expression of the genetic information to cell division. As a long polymer, chromatin is very flexible and may adopt a myriad of shapes. Globally, the polymer physics governing chromatin dynamics is very well understood. But chromatin is not uniform and regions of it, with chemical modifications and bound effectors, form domains and compartments through mechanisms not yet clear. Polymer models have been successfully used to investigate these mechanisms to explain cytological observations and build hypothesis for experimental validation. Many different approaches to conceptualise chromatin in polymer models can be envisioned and each reflects different aspects. Here, we compare recent approaches that aim at reproducing prominent features of interphase chromatin organisation: the compartmentalisation into eu- and heterochromatin compartments, the formation of a nucleolus, chromatin loops and the rosette and Rabl conformations of interphase chromosomes. We highlight commonalities and contradictions that point to a modulation of the mechanisms involved to fine degree. Consolidating models will require the inclusion of yet hidden or neglected parameters.
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21
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Chapman KB, Filipsky F, Peschke N, Gelléri M, Weinhardt V, Braun A, Hausmann M, Cremer C. A comprehensive method to study the DNA's association with lamin and chromatin compaction in intact cell nuclei at super resolution. NANOSCALE 2023; 15:742-756. [PMID: 36524744 PMCID: PMC9813922 DOI: 10.1039/d2nr02684h] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 10/14/2022] [Indexed: 06/17/2023]
Abstract
Super-resolution fluorescence microscopy has revolutionized multicolor imaging of nuclear structures due to the combination of high labeling specificity and high resolution. Here we expanded the recently developed fBALM (DNA structure fluctuation-assisted binding activated localization microscopy) method by developing a stable methodological sequence that enables dual-color imaging of high-resolution genomic DNA together with an immunofluorescently labeled intranuclear protein. Our measurements of the nuclear periphery, imaging DNA and LaminB1 in biologically relevant samples, show that this novel dual-color imaging method is feasible for further quantitative evaluations. We were able to study the relative spatial signal organization between DNA and LaminB1 by means of highly specific colocalization measurements at nanometer resolution. Measurements were performed with and without the antifade embedding medium ProLong Gold, which proved to be essential for imaging of LaminB1, but not for imaging of SytoxOrange labeled DNA. The localization precision was used to differentiate between localizations with higher and lower amounts of emitting photons. We interpret high intensity localizations to be renatured DNA sections in which a high amount of Sytox Orange molecules were bound. This could give insight into the denaturation kinetics of DNA during fBALM. These results were further complemented by measurements of γH2AX and H3K9me3 signal organization to demonstrate differences within the chromatin landscape, which were quantified with image processing methods such as Voronoi segmentation.
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Affiliation(s)
- Katarina B Chapman
- Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany.
- Institute of Molecular Biology, Ackermannweg 4, 55128 Mainz, Germany
| | - Filip Filipsky
- Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Nicolas Peschke
- Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany.
| | - Márton Gelléri
- Institute of Molecular Biology, Ackermannweg 4, 55128 Mainz, Germany
| | - Venera Weinhardt
- Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
| | - Andrejs Braun
- Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Michael Hausmann
- Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany.
| | - Christoph Cremer
- Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany.
- Institute of Molecular Biology, Ackermannweg 4, 55128 Mainz, Germany
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22
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Mansisidor AR, Risca VI. Chromatin accessibility: methods, mechanisms, and biological insights. Nucleus 2022; 13:236-276. [PMID: 36404679 PMCID: PMC9683059 DOI: 10.1080/19491034.2022.2143106] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/23/2022] [Accepted: 10/30/2022] [Indexed: 11/22/2022] Open
Abstract
Access to DNA is a prerequisite to the execution of essential cellular processes that include transcription, replication, chromosomal segregation, and DNA repair. How the proteins that regulate these processes function in the context of chromatin and its dynamic architectures is an intensive field of study. Over the past decade, genome-wide assays and new imaging approaches have enabled a greater understanding of how access to the genome is regulated by nucleosomes and associated proteins. Additional mechanisms that may control DNA accessibility in vivo include chromatin compaction and phase separation - processes that are beginning to be understood. Here, we review the ongoing development of accessibility measurements, we summarize the different molecular and structural mechanisms that shape the accessibility landscape, and we detail the many important biological functions that are linked to chromatin accessibility.
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Affiliation(s)
- Andrés R. Mansisidor
- Laboratory of Genome Architecture and Dynamics, The Rockefeller University, New York, NY
| | - Viviana I. Risca
- Laboratory of Genome Architecture and Dynamics, The Rockefeller University, New York, NY
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23
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Correa Tedesco FG, Aguilar PS, Estrada L. Correlation analyses reveal differential diffusion behavior of eisosomal proteins between mother and daughter cells. Methods Appl Fluoresc 2022; 10. [PMID: 36067776 DOI: 10.1088/2050-6120/ac8fe1] [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: 06/12/2022] [Accepted: 09/05/2022] [Indexed: 11/12/2022]
Abstract
Eisosomes are nanoscale plasma membrane domains shaped as furrow-like invaginations. In Saccharomyces cerevisiae these relatively immobile and uniform structures are mainly composed of two cytoplasmic proteins Pil1 and Lsp1. The present work uses fluctuation of fluorescence signals and analytical methods to determine Pil1 and Lsp1 dynamics at different subcellular locations. Using scanning techniques and autocorrelation analysis we determine that the cytoplasmic pools of Pil1 and Lsp1 behave mainly by passive diffusion. Single-point FCS experiments performed at several subcellular locations reveal that Pil1 mobility is faster in daughter cells. Furthermore, pair correlation function analysis indicates a rapid dynamic of Pil1 near the plasma membrane of growing yeast buds, where the membrane is expected to be actively assembling eisosomes.
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Affiliation(s)
- Francisco G Correa Tedesco
- Laboratorio de Biología Celular de Membranas, Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín, San Martín, Argentina, Campus Miguelete, Buenos Aires, 1650, ARGENTINA
| | - Pablo Sebastian Aguilar
- Laboratorio de Biología Celular de Membranas, Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín, San Martín, Argentina, Campus Miguelete, Buenos Aires, 1650, ARGENTINA
| | - Laura Estrada
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, UBA,, Intendente Guiraldes 2160, Pabellon 1, CABA, Buenos Aires, 1428, ARGENTINA
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24
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Roemer A, Mohammed L, Strickfaden H, Underhill DA, Hendzel MJ. Mechanisms governing the accessibility of DNA damage proteins to constitutive heterochromatin. Front Genet 2022; 13:876862. [PMID: 36092926 PMCID: PMC9458887 DOI: 10.3389/fgene.2022.876862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 07/18/2022] [Indexed: 12/05/2022] Open
Abstract
Chromatin is thought to regulate the accessibility of the underlying DNA sequence to machinery that transcribes and repairs the DNA. Heterochromatin is chromatin that maintains a sufficiently high density of DNA packing to be visible by light microscopy throughout the cell cycle and is thought to be most restrictive to transcription. Several studies have suggested that larger proteins and protein complexes are attenuated in their access to heterochromatin. In addition, heterochromatin domains may be associated with phase separated liquid condensates adding further complexity to the regulation of protein concentration within chromocenters. This provides a solvent environment distinct from the nucleoplasm, and proteins that are not size restricted in accessing this liquid environment may partition between the nucleoplasm and heterochromatin based on relative solubility. In this study, we assessed the accessibility of constitutive heterochromatin in mouse cells, which is organized into large and easily identifiable chromocenters, to fluorescently tagged DNA damage response proteins. We find that proteins larger than the expected 10 nm size limit can access the interior of heterochromatin. We find that the sensor proteins Ku70 and PARP1 enrich in mouse chromocenters. At the same time, MRE11 shows variability within an asynchronous population that ranges from depleted to enriched but is primarily homogeneously distribution between chromocenters and the nucleoplasm. While larger downstream proteins such as ATM, BRCA1, and 53BP1 are commonly depleted in chromocenters, they show a wide range of concentrations, with none being depleted beyond approximately 75%. Contradicting exclusively size-dependent accessibility, many smaller proteins, including EGFP, are also depleted in chromocenters. Our results are consistent with minimal size-dependent selectivity but a distinct solvent environment explaining reduced concentrations of diffusing nucleoplasmic proteins within the volume of the chromocenter.
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25
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Kim Y, Joo S, Kim WK, Jeon JH. Active Diffusion of Self-Propelled Particles in Flexible Polymer Networks. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Yeongjin Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang37673, Republic of Korea
| | - Sungmin Joo
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang37673, Republic of Korea
| | - Won Kyu Kim
- School of Computational Sciences, Korea Institute for Advanced Study (KIAS), Seoul02455, Republic of Korea
| | - Jae-Hyung Jeon
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang37673, Republic of Korea
- Asia Pacific Center for Theoretical Physics (APCTP), Pohang37673, Republic of Korea
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26
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Zhang M, Díaz-Celis C, Onoa B, Cañari-Chumpitaz C, Requejo KI, Liu J, Vien M, Nogales E, Ren G, Bustamante C. Molecular organization of the early stages of nucleosome phase separation visualized by cryo-electron tomography. Mol Cell 2022; 82:3000-3014.e9. [PMID: 35907400 DOI: 10.1016/j.molcel.2022.06.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 05/09/2022] [Accepted: 06/28/2022] [Indexed: 12/16/2022]
Abstract
It has been proposed that the intrinsic property of nucleosome arrays to undergo liquid-liquid phase separation (LLPS) in vitro is responsible for chromatin domain organization in vivo. However, understanding nucleosomal LLPS has been hindered by the challenge to characterize the structure of the resulting heterogeneous condensates. We used cryo-electron tomography and deep-learning-based 3D reconstruction/segmentation to determine the molecular organization of condensates at various stages of LLPS. We show that nucleosomal LLPS involves a two-step process: a spinodal decomposition process yielding irregular condensates, followed by their unfavorable conversion into more compact, spherical nuclei that grow into larger spherical aggregates through accretion of spinodal materials or by fusion with other spherical condensates. Histone H1 catalyzes more than 10-fold the spinodal-to-spherical conversion. We propose that this transition involves exposure of nucleosome hydrophobic surfaces causing modified inter-nucleosome interactions. These results suggest a physical mechanism by which chromatin may transition from interphase to metaphase structures.
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Affiliation(s)
- Meng Zhang
- Applied Science and Technology Graduate Group, University of California, Berkeley, CA, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - César Díaz-Celis
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Bibiana Onoa
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | | | - Katherinne I Requejo
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Michael Vien
- Department of Physics, University of California, Berkeley, CA, USA
| | - Eva Nogales
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA; Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Carlos Bustamante
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA; Department of Chemistry, University of California, Berkeley, CA, USA; Department of Physics, University of California, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA; Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; Kavli Energy Nanoscience Institute, University of California, Berkeley, CA, USA.
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27
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Dynamic Mode Decomposition of Fluorescence Loss in Photobleaching Microscopy Data for Model-Free Analysis of Protein Transport and Aggregation in Living Cells. SENSORS 2022; 22:s22134731. [PMID: 35808232 PMCID: PMC9269098 DOI: 10.3390/s22134731] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/16/2022] [Accepted: 06/20/2022] [Indexed: 02/05/2023]
Abstract
The phase separation and aggregation of proteins are hallmarks of many neurodegenerative diseases. These processes can be studied in living cells using fluorescent protein constructs and quantitative live-cell imaging techniques, such as fluorescence recovery after photobleaching (FRAP) or the related fluorescence loss in photobleaching (FLIP). While the acquisition of FLIP images is straightforward on most commercial confocal microscope systems, the analysis and computational modeling of such data is challenging. Here, a novel model-free method is presented, which resolves complex spatiotemporal fluorescence-loss kinetics based on dynamic-mode decomposition (DMD) of FLIP live-cell image sequences. It is shown that the DMD of synthetic and experimental FLIP image series (DMD-FLIP) allows for the unequivocal discrimination of subcellular compartments, such as nuclei, cytoplasm, and protein condensates based on their differing transport and therefore fluorescence loss kinetics. By decomposing fluorescence-loss kinetics into distinct dynamic modes, DMD-FLIP will enable researchers to study protein dynamics at each time scale individually. Furthermore, it is shown that DMD-FLIP is very efficient in denoising confocal time series data. Thus, DMD-FLIP is an easy-to-use method for the model-free detection of barriers to protein diffusion, of phase-separated protein assemblies, and of insoluble protein aggregates. It should, therefore, find wide application in the analysis of protein transport and aggregation, in particular in relation to neurodegenerative diseases and the formation of protein condensates in living cells.
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28
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Solano A, Lou J, Scipioni L, Gratton E, Hinde E. Radial pair correlation of molecular brightness fluctuations maps protein diffusion as a function of oligomeric state within live-cell nuclear architecture. Biophys J 2022; 121:2152-2167. [PMID: 35490296 PMCID: PMC9247470 DOI: 10.1016/j.bpj.2022.04.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 11/16/2021] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
Nuclear proteins can modulate their DNA binding activity and the exploration volume available during DNA target search by self-associating into higher-order oligomers. Directly tracking this process in the nucleoplasm of a living cell is, however, a complex task. Thus, here we present a microscopy method based on radial pair correlation of molecular brightness fluctuations (radial pCOMB) that can extract the mobility of a fluorescently tagged nuclear protein as a function of its oligomeric state and spatiotemporally map the anisotropy of this parameter with respect to nuclear architecture. By simply performing a rapid frame scan acquisition, radial pCOMB has the capacity to detect, within each pixel, protein oligomer formation and the size-dependent obstruction nuclear architecture imparts on this complex's transport across sub-micrometer distances. From application of radial pCOMB to an oligomeric transcription factor and DNA repair protein, we demonstrate that homo-oligomer formation differentially regulates chromatin accessibility and interaction with the DNA template.
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Affiliation(s)
- Ashleigh Solano
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Jieqiong Lou
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Lorenzo Scipioni
- Department of Biomedical Engineering, University of California, Irvine
| | - Enrico Gratton
- Department of Biomedical Engineering, University of California, Irvine.
| | - Elizabeth Hinde
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne.
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29
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Mitrentsi I, Lou J, Kerjouan A, Verigos J, Reina-San-Martin B, Hinde E, Soutoglou E. Heterochromatic repeat clustering imposes a physical barrier on homologous recombination to prevent chromosomal translocations. Mol Cell 2022; 82:2132-2147.e6. [PMID: 35447083 PMCID: PMC9616805 DOI: 10.1016/j.molcel.2022.03.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 12/15/2021] [Accepted: 03/28/2022] [Indexed: 01/01/2023]
Abstract
Mouse pericentromeric DNA is composed of tandem major satellite repeats, which are heterochromatinized and cluster together to form chromocenters. These clusters are refractory to DNA repair through homologous recombination (HR). The mechanisms by which pericentromeric heterochromatin imposes a barrier on HR and the implications of repeat clustering are unknown. Here, we compare the spatial recruitment of HR factors upon double-stranded DNA breaks (DSBs) induced in human and mouse pericentromeric heterochromatin, which differ in their capacity to form clusters. We show that while DSBs increase the accessibility of human pericentromeric heterochromatin by disrupting HP1α dimerization, mouse pericentromeric heterochromatin repeat clustering imposes a physical barrier that requires many layers of de-compaction to be accessed. Our results support a model in which the 3D organization of heterochromatin dictates the spatial activation of DNA repair pathways and is key to preventing the activation of HR within clustered repeats and the onset of chromosomal translocations. DSBs at human pericentric HC are positionally stable and recruit HR factors Repeat clustering restricts Rad51 at the periphery of heterochromatin Human pericentromeric HC is more accessible to HR factors than mouse HC Inhibition of DSB relocation at clustered repeats leads to translocations
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Affiliation(s)
- Ioanna Mitrentsi
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France; Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Jieqiong Lou
- School of Physics, University of Melbourne, Melbourne, VIC, Australia
| | - Adèle Kerjouan
- School of Physics, University of Melbourne, Melbourne, VIC, Australia
| | - John Verigos
- Genome Damage and Stability Centre, Sussex University, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK
| | - Bernardo Reina-San-Martin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France; Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Elizabeth Hinde
- School of Physics, University of Melbourne, Melbourne, VIC, Australia; Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, VIC, Australia
| | - Evi Soutoglou
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France; Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France; Université de Strasbourg, Illkirch, France; Genome Damage and Stability Centre, Sussex University, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK.
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30
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Lejart A, Zentout S, Chapuis C, D'Augustin O, Smith R, Salbert G, Huet S. The N-terminal domain of TET1 promotes the formation of dense chromatin regions refractory to transcription. Chromosoma 2022; 131:47-58. [PMID: 35235010 DOI: 10.1007/s00412-022-00769-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/24/2022] [Accepted: 01/31/2022] [Indexed: 11/03/2022]
Abstract
TET (ten-eleven translocation) enzymes initiate active cytosine demethylation via the oxidation of 5-methylcytosine. TET1 is composed of a C-terminal domain, which bears the catalytic activity of the enzyme, and a N-terminal region that is less well characterized except for the CXXC domain responsible for the targeting to CpG islands. While cytosine demethylation induced by TET1 promotes transcription, this protein also interacts with chromatin-regulating factors that rather silence this process, the coordination between these two opposite functions of TET1 being unclear. In the present work, we uncover a new function of the N-terminal part of the TET1 protein in the regulation of the chromatin architecture. This domain of the protein promotes the establishment of a compact chromatin architecture displaying reduced exchange rate of core histones and partial dissociation of the histone linker. This chromatin reorganization process, which does not rely on the CXXC domain, is associated with a global shutdown of transcription and an increase in heterochromatin-associated histone epigenetic marks. Based on these findings, we propose that the dense chromatin organization generated by the N-terminal domain of TET1 could contribute to restraining the transcription enhancement induced by the DNA demethylation activity of this enzyme.
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Affiliation(s)
- Audrey Lejart
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, 35000, Rennes, France
| | - Siham Zentout
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, 35000, Rennes, France
| | - Catherine Chapuis
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, 35000, Rennes, France
| | - Ostiane D'Augustin
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, 35000, Rennes, France
- Institut de Biologie François Jacob, Institute of Cellular and Molecular Radiobiology, Université Paris-Saclay, Université de Paris, CEA, 92265, Fontenay-aux-Roses, France
| | - Rebecca Smith
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, 35000, Rennes, France
| | - Gilles Salbert
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, 35000, Rennes, France.
| | - Sébastien Huet
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, Santé, Innovation Technologique de Rennes) - UMS 3480, US 018, 35000, Rennes, France.
- Institut Universitaire de France, Paris, France.
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31
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Kim Y, Lizana L, Jeon JH. Fractal and Knot-Free Chromosomes Facilitate Nucleoplasmic Transport. PHYSICAL REVIEW LETTERS 2022; 128:038101. [PMID: 35119884 DOI: 10.1103/physrevlett.128.038101] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 11/24/2021] [Indexed: 06/14/2023]
Abstract
Chromosomes in the nucleus assemble into hierarchies of 3D domains that, during interphase, share essential features with a knot-free condensed polymer known as the fractal globule (FG). The FG-like chromosome likely affects macromolecular transport, yet its characteristics remain poorly understood. Using computer simulations and scaling analysis, we show that the 3D folding and macromolecular size of the chromosomes determine their transport characteristics. Large-scale subdiffusion occurs at a critical particle size where the network of accessible volumes is critically connected. Condensed chromosomes have connectivity networks akin to simple Bernoulli bond percolation clusters, regardless of the polymer models. However, even if the network structures are similar, the tracer's walk dimension varies. It turns out that the walk dimension depends on the network topology of the accessible volume and dynamic heterogeneity of the tracer's hopping rate. We find that the FG structure has a smaller walk dimension than other random geometries, suggesting that the FG-like chromosome structure accelerates macromolecular diffusion and target-search.
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Affiliation(s)
- Yeonghoon Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Ludvig Lizana
- Integrated Science Lab, Department of Physics, Umeå University, Umeå 90187, Sweden
| | - Jae-Hyung Jeon
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Asia Pacific Center for Theoretical Physics, Pohang 37673, Republic of Korea
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32
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Zunke C, Bewerunge J, Platten F, Egelhaaf SU, Godec A. First-passage statistics of colloids on fractals: Theory and experimental realization. SCIENCE ADVANCES 2022; 8:eabk0627. [PMID: 35061533 PMCID: PMC8782457 DOI: 10.1126/sciadv.abk0627] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 11/29/2021] [Indexed: 05/30/2023]
Abstract
In nature and technology, particle dynamics frequently occur in complex environments, for example in restricted geometries or crowded media. These dynamics have often been modeled invoking a fractal structure of the medium although the fractal structure was only indirectly inferred through the dynamics. Moreover, systematic studies have not yet been performed. Here, colloidal particles moving in a laser speckle pattern are used as a model system. In this case, the experimental observations can be reliably traced to the fractal structure of the underlying medium with an adjustable fractal dimension. First-passage time statistics reveal that the particles explore the speckle in a self-similar, fractal manner at least over four decades in time and on length scales up to 20 times the particle radius. The requirements for fractal diffusion to be applicable are laid out, and methods to extract the fractal dimension are established.
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Affiliation(s)
- Christoph Zunke
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Jörg Bewerunge
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Florian Platten
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
- Institute of Biological Information Processing, Biomacromolecular Systems and Processes (IBI-4), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Stefan U. Egelhaaf
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Aljaž Godec
- Mathematical bioPhysics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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33
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Datta S, Patel M, Kashyap S, Patel D, Singh U. Chimeric chromosome landscapes of human somatic cell cultures show dependence on stress and regulation of genomic repeats by CGGBP1. Oncotarget 2022; 13:136-155. [PMID: 35070079 PMCID: PMC8765472 DOI: 10.18632/oncotarget.28174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/20/2021] [Indexed: 11/25/2022] Open
Abstract
Genomes of somatic cells in culture are prone to spontaneous mutations due to errors in replication and DNA repair. Some of these errors, such as chromosomal fusions, are not rectifiable and subject to selection or elimination in growing cultures. Somatic cell cultures are thus expected to generate background levels of potentially stable chromosomal chimeras. A description of the landscape of such spontaneously generated chromosomal chimeras in cultured cells will help understand the factors affecting somatic mosaicism. Here we show that short homology-associated non-homologous chromosomal chimeras occur in normal human fibroblasts and HEK293T cells at genomic repeats. The occurrence of chromosomal chimeras is enhanced by heat stress and depletion of a repeat regulatory protein CGGBP1. We also present evidence of homologous chromosomal chimeras between allelic copies in repeat-rich DNA obtained by methylcytosine immunoprecipitation. The formation of homologous chromosomal chimeras at Alu and L1 repeats increases upon depletion of CGGBP1. Our data are derived from de novo sequencing from three different cell lines under different experimental conditions and our chromosomal chimera detection pipeline is applicable to long as well as short read sequencing platforms. These findings present significant information about the generation, sensitivity and regulation of somatic mosaicism in human cell cultures.
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Affiliation(s)
- Subhamoy Datta
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Manthan Patel
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
- Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AD, UK
| | - Sukesh Kashyap
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Divyesh Patel
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
- Current address: Research Programs Unit, Applied Tumor Genomics Program, Faculty of Medicine, University of Helsinki, Biomedicum, Helsinki 00290, Finland
| | - Umashankar Singh
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
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34
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Sallaberry I, Luszczak A, Philipp N, Navarro GSC, Gabriel MV, Gratton E, Gamarnik AV, Estrada LC. In vivo pair correlation microscopy reveals dengue virus capsid protein nucleocytoplasmic bidirectional movement in mammalian infected cells. Sci Rep 2021; 11:24415. [PMID: 34952906 PMCID: PMC8709865 DOI: 10.1038/s41598-021-03854-z] [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: 09/24/2021] [Accepted: 12/09/2021] [Indexed: 12/22/2022] Open
Abstract
Flaviviruses are major human disease-causing pathogens, including dengue virus (DENV), Zika virus, yellow fever virus and others. DENV infects hundreds of millions of people per year around the world, causing a tremendous social and economic burden. DENV capsid (C) protein plays an essential role during genome encapsidation and viral particle formation. It has been previously shown that DENV C enters the nucleus in infected cells. However, whether DENV C protein exhibits nuclear export remains unclear. By spatially cross-correlating different regions of the cell, we investigated DENV C movement across the nuclear envelope during the infection cycle. We observed that transport takes place in both directions and with similar translocation times (in the ms time scale) suggesting a bidirectional movement of both C protein import and export.Furthermore, from the pair cross-correlation functions in cytoplasmic or nuclear regions we found two populations of C molecules in each compartment with fast and slow mobilities. While in the cytoplasm the correlation times were in the 2-6 and 40-110 ms range for the fast and slow mobility populations respectively, in the cell nucleus they were 1-10 and 25-140 ms range, respectively. The fast mobility of DENV C in cytoplasmic and nuclear regions agreed with the diffusion coefficients from Brownian motion previously reported from correlation analysis. These studies provide the first evidence of DENV C shuttling from and to the nucleus in infected cells, opening new venues for antiviral interventions.
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Affiliation(s)
- Ignacio Sallaberry
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-National Research Council for Science and Technology (CONICET), 1428, Buenos Aires, Argentina
| | - Alexis Luszczak
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-National Research Council for Science and Technology (CONICET), 1428, Buenos Aires, Argentina
| | - Natalia Philipp
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-National Research Council for Science and Technology (CONICET), 1428, Buenos Aires, Argentina
| | - Guadalupe S Costa Navarro
- Fundación Instituto Leloir-National Research Council for Science and Technology (CONICET), 1405, Buenos Aires, Argentina
| | - Manuela V Gabriel
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-National Research Council for Science and Technology (CONICET), 1428, Buenos Aires, Argentina
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics and Beckman Laser Institute and Medical Clinic, University of California, Irvine, CA, USA
| | - Andrea V Gamarnik
- Fundación Instituto Leloir-National Research Council for Science and Technology (CONICET), 1405, Buenos Aires, Argentina
| | - Laura C Estrada
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA-National Research Council for Science and Technology (CONICET), 1428, Buenos Aires, Argentina.
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35
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Aho V, Salminen S, Mattola S, Gupta A, Flomm F, Sodeik B, Bosse JB, Vihinen-Ranta M. Infection-induced chromatin modifications facilitate translocation of herpes simplex virus capsids to the inner nuclear membrane. PLoS Pathog 2021; 17:e1010132. [PMID: 34910768 PMCID: PMC8673650 DOI: 10.1371/journal.ppat.1010132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/19/2021] [Indexed: 01/04/2023] Open
Abstract
Herpes simplex virus capsids are assembled and packaged in the nucleus and move by diffusion through the nucleoplasm to the nuclear envelope for egress. Analyzing their motion provides conclusions not only on capsid transport but also on the properties of the nuclear environment during infection. We utilized live-cell imaging and single-particle tracking to characterize capsid motion relative to the host chromatin. The data indicate that as the chromatin was marginalized toward the nuclear envelope it presented a restrictive barrier to the capsids. However, later in infection this barrier became more permissive and the probability of capsids to enter the chromatin increased. Thus, although chromatin marginalization initially restricted capsid transport to the nuclear envelope, a structural reorganization of the chromatin counteracted that to promote capsid transport later. Analyses of capsid motion revealed that it was subdiffusive, and that the diffusion coefficients were lower in the chromatin than in regions lacking chromatin. In addition, the diffusion coefficient in both regions increased during infection. Throughout the infection, the capsids were never enriched at the nuclear envelope, which suggests that instead of nuclear export the transport through the chromatin is the rate-limiting step for the nuclear egress of capsids. This provides motivation for further studies by validating the importance of intranuclear transport to the life cycle of HSV-1.
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Affiliation(s)
- Vesa Aho
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Sami Salminen
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Salla Mattola
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Alka Gupta
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Felix Flomm
- HPI, Leibniz-Institute for Experimental Virology, Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- Hannover Medical School, Institute of Virology, Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Beate Sodeik
- Hannover Medical School, Institute of Virology, Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Jens B. Bosse
- HPI, Leibniz-Institute for Experimental Virology, Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- Hannover Medical School, Institute of Virology, Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Maija Vihinen-Ranta
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
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36
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Abstract
To predict transcription, one needs a mechanistic understanding of how the numerous required transcription factors (TFs) explore the nuclear space to find their target genes, assemble, cooperate, and compete with one another. Advances in fluorescence microscopy have made it possible to visualize real-time TF dynamics in living cells, leading to two intriguing observations: first, most TFs contact chromatin only transiently; and second, TFs can assemble into clusters through their intrinsically disordered regions. These findings suggest that highly dynamic events and spatially structured nuclear microenvironments might play key roles in transcription regulation that are not yet fully understood. The emerging model is that while some promoters directly convert TF-binding events into on/off cycles of transcription, many others apply complex regulatory layers that ultimately lead to diverse phenotypic outputs. Cracking this kinetic code is an ongoing and challenging task that is made possible by combining innovative imaging approaches with biophysical models.
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Affiliation(s)
- Feiyue Lu
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
| | - Timothée Lionnet
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
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37
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Mohanta TK, Mishra AK, Al-Harrasi A. The 3D Genome: From Structure to Function. Int J Mol Sci 2021; 22:11585. [PMID: 34769016 PMCID: PMC8584255 DOI: 10.3390/ijms222111585] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 01/09/2023] Open
Abstract
The genome is the most functional part of a cell, and genomic contents are organized in a compact three-dimensional (3D) structure. The genome contains millions of nucleotide bases organized in its proper frame. Rapid development in genome sequencing and advanced microscopy techniques have enabled us to understand the 3D spatial organization of the genome. Chromosome capture methods using a ligation approach and the visualization tool of a 3D genome browser have facilitated detailed exploration of the genome. Topologically associated domains (TADs), lamin-associated domains, CCCTC-binding factor domains, cohesin, and chromatin structures are the prominent identified components that encode the 3D structure of the genome. Although TADs are the major contributors to 3D genome organization, they are absent in Arabidopsis. However, a few research groups have reported the presence of TAD-like structures in the plant kingdom.
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Affiliation(s)
- Tapan Kumar Mohanta
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman
| | - Awdhesh Kumar Mishra
- Department of Biotechnology, Yeungnam University, Gyeongsan 38541, Gyeongsangbuk-do, Korea; or
| | - Ahmed Al-Harrasi
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman
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38
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Zentout S, Smith R, Jacquier M, Huet S. New Methodologies to Study DNA Repair Processes in Space and Time Within Living Cells. Front Cell Dev Biol 2021; 9:730998. [PMID: 34589495 PMCID: PMC8473836 DOI: 10.3389/fcell.2021.730998] [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: 06/25/2021] [Accepted: 08/25/2021] [Indexed: 01/02/2023] Open
Abstract
DNA repair requires a coordinated effort from an array of factors that play different roles in the DNA damage response from recognizing and signaling the presence of a break, creating a repair competent environment, and physically repairing the lesion. Due to the rapid nature of many of these events, live-cell microscopy has become an invaluable method to study this process. In this review we outline commonly used tools to induce DNA damage under the microscope and discuss spatio-temporal analysis tools that can bring added information regarding protein dynamics at sites of damage. In particular, we show how to go beyond the classical analysis of protein recruitment curves to be able to assess the dynamic association of the repair factors with the DNA lesions as well as the target-search strategies used to efficiently find these lesions. Finally, we discuss how the use of mathematical models, combined with experimental evidence, can be used to better interpret the complex dynamics of repair proteins at DNA lesions.
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Affiliation(s)
- Siham Zentout
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes)-UMR 6290, BIOSIT-UMS 3480, Rennes, France
| | - Rebecca Smith
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes)-UMR 6290, BIOSIT-UMS 3480, Rennes, France
| | - Marine Jacquier
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes)-UMR 6290, BIOSIT-UMS 3480, Rennes, France
| | - Sébastien Huet
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes)-UMR 6290, BIOSIT-UMS 3480, Rennes, France
- Institut Universitaire de France, Paris, France
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39
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Mazzocca M, Fillot T, Loffreda A, Gnani D, Mazza D. The needle and the haystack: single molecule tracking to probe the transcription factor search in eukaryotes. Biochem Soc Trans 2021; 49:1121-1132. [PMID: 34003257 PMCID: PMC8286828 DOI: 10.1042/bst20200709] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 12/13/2022]
Abstract
Transcription factors (TFs) regulate transcription of their target genes by identifying and binding to regulatory regions of the genome among billions of potential non-specific decoy sites, a task that is often presented as a 'needle in the haystack' challenge. The TF search process is now well understood in bacteria, but its characterization in eukaryotes needs to account for the complex organization of the nuclear environment. Here we review how live-cell single molecule tracking is starting to shed light on the TF search mechanism in the eukaryotic cell and we outline the future challenges to tackle in order to understand how nuclear organization modulates the TF search process in physiological and pathological conditions.
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Affiliation(s)
- Matteo Mazzocca
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Tom Fillot
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Alessia Loffreda
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Daniela Gnani
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Davide Mazza
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
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40
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Liu J, Xie D, Liu Z. Probing nucleus-enriched proteins in single living cells via a subcellular-resolved plasmonic immunosandwich assay. Analyst 2021; 146:2878-2885. [PMID: 33687045 DOI: 10.1039/d1an00003a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Nuclear proteins are crucial in cells and are greatly linked to various biological functions. Abnormal expression of nuclear proteins is associated with many diseases ranging from inflammation to cancer. However, it remains challenging to detect nuclear proteins in single cells because of their low abundance and complex subcellular environment. Herein, we report a subcellular-resolved plasmonic immunosandwich assay (srPISA), for probing nucleus-enriched proteins in single living cells with minimal disruption. We demonstrated the specific extraction and ultrasensitive detection capabilities of the srPISA by probing low-copy-number nuclear telomerase in single living cells and further compared the telomerase expression levels in these single cells. Additionally, we showed the subcellular resolving capability of the srPISA by probing the spatial distribution of smad2 in the nucleus and cytoplasm of single living cells. We found that smad2 was expressed both in the nucleus and the cytoplasm, but showed different expression levels. Moreover, smad2 distributed more homogeneously in the nucleus than in the cytoplasm. Finally, the srPISA of nuclear telomerase in cell division strongly verified that the subcellular analytical results obtained by the srPISA are reliable. Overall, the srPISA approach allowed specific extraction and ultrasensitive detection of target low-copy-number proteins at the subcellular level, providing a unique and powerful single cell analysis tool for cell biology studies.
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Affiliation(s)
- Jia Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, P. R. China.
| | - Dan Xie
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, P. R. China.
| | - Zhen Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, P. R. China.
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41
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Noa A, Kuan HS, Aschmann V, Zaburdaev V, Hilbert L. The hierarchical packing of euchromatin domains can be described as multiplicative cascades. PLoS Comput Biol 2021; 17:e1008974. [PMID: 33951053 PMCID: PMC8128263 DOI: 10.1371/journal.pcbi.1008974] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 05/17/2021] [Accepted: 04/16/2021] [Indexed: 01/24/2023] Open
Abstract
The genome is packed into the cell nucleus in the form of chromatin. Biochemical approaches have revealed that chromatin is packed within domains, which group into larger domains, and so forth. Such hierarchical packing is equally visible in super-resolution microscopy images of large-scale chromatin organization. While previous work has suggested that chromatin is partitioned into distinct domains via microphase separation, it is unclear how these domains organize into this hierarchical packing. A particular challenge is to find an image analysis approach that fully incorporates such hierarchical packing, so that hypothetical governing mechanisms of euchromatin packing can be compared against the results of such an analysis. Here, we obtain 3D STED super-resolution images from pluripotent zebrafish embryos labeled with improved DNA fluorescence stains, and demonstrate how the hierarchical packing of euchromatin in these images can be described as multiplicative cascades. Multiplicative cascades are an established theoretical concept to describe the placement of ever-smaller structures within bigger structures. Importantly, these cascades can generate artificial image data by applying a single rule again and again, and can be fully specified using only four parameters. Here, we show how the typical patterns of euchromatin organization are reflected in the values of these four parameters. Specifically, we can pinpoint the values required to mimic a microphase-separated state of euchromatin. We suggest that the concept of multiplicative cascades can also be applied to images of other types of chromatin. Here, cascade parameters could serve as test quantities to assess whether microphase separation or other theoretical models accurately reproduce the hierarchical packing of chromatin.
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Affiliation(s)
- Amra Noa
- Institute of Biological and Chemical Systems, Dept. Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Hui-Shun Kuan
- Chair of Mathematics in Life Sciences, Dept. Biology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Vera Aschmann
- Master’s Program Biology, Faculty for Chemistry and Biosciences, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Vasily Zaburdaev
- Chair of Mathematics in Life Sciences, Dept. Biology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Lennart Hilbert
- Institute of Biological and Chemical Systems, Dept. Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
- Zoological Institute, Dept. Systems Biology and Bioinformatics, Karlsruhe Institute of Technology, Karlsruhe, Germany
- * E-mail:
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42
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Fortuny A, Chansard A, Caron P, Chevallier O, Leroy O, Renaud O, Polo SE. Imaging the response to DNA damage in heterochromatin domains reveals core principles of heterochromatin maintenance. Nat Commun 2021; 12:2428. [PMID: 33893291 PMCID: PMC8065061 DOI: 10.1038/s41467-021-22575-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 03/17/2021] [Indexed: 02/02/2023] Open
Abstract
Heterochromatin is a critical chromatin compartment, whose integrity governs genome stability and cell fate transitions. How heterochromatin features, including higher-order chromatin folding and histone modifications associated with transcriptional silencing, are maintained following a genotoxic stress challenge is unknown. Here, we establish a system for targeting UV damage to pericentric heterochromatin in mammalian cells and for tracking the heterochromatin response to UV in real time. We uncover profound heterochromatin compaction changes during repair, orchestrated by the UV damage sensor DDB2, which stimulates linker histone displacement from chromatin. Despite massive heterochromatin unfolding, heterochromatin-specific histone modifications and transcriptional silencing are maintained. We unveil a central role for the methyltransferase SETDB1 in the maintenance of heterochromatic histone marks after UV. SETDB1 coordinates histone methylation with new histone deposition in damaged heterochromatin, thus protecting cells from genome instability. Our data shed light on fundamental molecular mechanisms safeguarding higher-order chromatin integrity following DNA damage.
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Affiliation(s)
- Anna Fortuny
- Epigenetics and Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France
| | - Audrey Chansard
- Epigenetics and Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France
| | - Pierre Caron
- Epigenetics and Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France
| | - Odile Chevallier
- Epigenetics and Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France
| | - Olivier Leroy
- Cell and Tissue Imaging Facility, UMR3215 PICT-IBiSA, Institut Curie, Paris, France
| | - Olivier Renaud
- Cell and Tissue Imaging Facility, UMR3215 PICT-IBiSA, Institut Curie, Paris, France
| | - Sophie E Polo
- Epigenetics and Cell Fate Centre, UMR7216 CNRS, Université de Paris, Paris, France.
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43
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Lebedev DV, Egorov VV, Shvetsov AV, Zabrodskaya YA, Isaev-Ivanov VV, Konevega AL. Neutron Scattering Techniques and Complementary Methods for Structural and Functional Studies of Biological Macromolecules and Large Macromolecular Complexes. CRYSTALLOGR REP+ 2021. [DOI: 10.1134/s1063774521020103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abstract
The review describes the application of small-angle scattering (SAS) of neutrons and complementary methods to study the structures of biomacromolecules. Here we cover SAS techniques, such as the contrast variation, the neutron spin-echo, and the solution of direct and inverse problems of three-dimensional reconstruction of the structures of macromolecules from SAS spectra by means of molecular modeling. A special section is devoted to specific objects of research, such as supramolecular complexes, influenza virus nucleoprotein, and chromatin.
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44
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Kienle DF, Schwartz DK. Single molecule characterization of anomalous transport in a thin, anisotropic film. Anal Chim Acta 2021; 1154:338331. [PMID: 33736806 DOI: 10.1016/j.aca.2021.338331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/01/2021] [Accepted: 02/14/2021] [Indexed: 01/07/2023]
Abstract
The diffusion of small, charged molecules incorporated in an anisotropic polyelectrolyte multilayer (PEM) was tracked in three dimensions by combining single-molecule fluorescence localization (to characterize lateral diffusion) with Förster resonance energy transfer (FRET) between diffusing molecules and the supporting surface (to measure diffusion in the surface-normal direction). Analysis of the surface-normal diffusion required model-based statistical analysis to account for the inherently noisy FRET signal. Combining these distinct single-molecule methods, which are inherently sensitive to different length-scales, permitted simultaneous characterization of severely anisotropic diffusion, which was more than three orders of magnitude slower in the surface-normal direction. We hypothesize that the anomalously slow surface-normal diffusion was related to the periodic distribution of charge in the PEM, which created electrostatic barriers. The motion was strongly subdiffusive, with anomalous temporal scaling exponents in lateral and normal directions, suggesting a connection to the transient, random fractal conformation of polymer chains in the film's matrix.
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Affiliation(s)
- Daniel F Kienle
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80309, USA.
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45
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Redding S. Dynamic asymmetry and why chromatin defies simple physical definitions. Curr Opin Cell Biol 2021; 70:116-122. [PMID: 33812325 DOI: 10.1016/j.ceb.2021.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/16/2021] [Accepted: 02/19/2021] [Indexed: 01/09/2023]
Abstract
Recent experiments have demonstrated a nucleus where chromatin is molded into stable, interwoven loops. Yet, many of the proteins, which shape chromatin structure, bind only transiently. In those brief encounters, these dynamic proteins temporarily crosslink chromatin loops. While, on the average, individual crosslinks do not persist, in the aggregate, they are sufficient to create and maintain stable chromatin domains. Owing to the asymmetry in size and speed of molecules involved, this type of organization imparts unique biophysical properties-the slow (chromatin) component can exhibit gel-like behaviors, whereas the fast (protein) component allows domains to respond with liquid-like characteristics.
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Affiliation(s)
- Sy Redding
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94143, USA.
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46
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Bubak G, Kwapiszewska K, Kalwarczyk T, Bielec K, Andryszewski T, Iwan M, Bubak S, Hołyst R. Quantifying Nanoscale Viscosity and Structures of Living Cells Nucleus from Mobility Measurements. J Phys Chem Lett 2021; 12:294-301. [PMID: 33346672 DOI: 10.1021/acs.jpclett.0c03052] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding the mobility of nano-objects in the eukaryotic cell nucleus, at multiple length-scales, is essential for dissecting nuclear structure-function relationships both in space and in time. Here, we demonstrate, using single-molecule fluorescent correlation spectroscopies, that motion of inert probes (proteins, polymers, or nanoparticles) with diameters ranging from 2.6 to 150 nm is mostly unobstructed in a nucleus. Supported by the analysis of electron tomography images, these results advocate the ∼150 nm-wide interchromosomal channels filled with the aqueous diluted protein solution. The nucleus is percolated by these channels to allow various cargos to migrate freely at the nanoscale. We determined the volume of interchromosomal channels in the HeLa cell nucleus to 237 ± 61 fL, which constitutes 34% of the cell nucleus volume. The volume fraction of mobile proteins in channels equals 16% ± 4%, and the concentration is 1 mM.
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Affiliation(s)
- Grzegorz Bubak
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Karina Kwapiszewska
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Tomasz Kalwarczyk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Krzysztof Bielec
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Tomasz Andryszewski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Michalina Iwan
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Szymon Bubak
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Robert Hołyst
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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47
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Perea Paizal J, Au SH, Bakal C. Squeezing through the microcirculation: survival adaptations of circulating tumour cells to seed metastasis. Br J Cancer 2021; 124:58-65. [PMID: 33257836 PMCID: PMC7782506 DOI: 10.1038/s41416-020-01176-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/20/2022] Open
Abstract
During metastasis, tumour cells navigating the vascular circulatory system-circulating tumour cells (CTCs)-encounter capillary beds, where they start the process of extravasation. Biomechanical constriction forces exerted by the microcirculation compromise the survival of tumour cells within capillaries, but a proportion of CTCs manage to successfully extravasate and colonise distant sites. Despite the profound importance of this step in the progression of metastatic cancers, the factors about this deadly minority of cells remain elusive. Growing evidence suggests that mechanical forces exerted by the capillaries might induce adaptive mechanisms in CTCs, enhancing their survival and metastatic potency. Advances in microfluidics have enabled a better understanding of the cell-survival capabilities adopted in capillary-mimicking constrictions. In this review, we will highlight adaptations developed by CTCs to endure mechanical constraints in the microvasculature and outline how these mechanical forces might trigger dynamic changes towards a more invasive phenotype. A better understanding of the dynamic mechanisms adopted by CTCs within the microcirculation that ultimately lead to metastasis could open up novel therapeutic avenues.
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Affiliation(s)
- Julia Perea Paizal
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK.
- Division of Cancer Biology, Chester Beatty Laboratories, Institute of Cancer Research, 237 Fulham Road, London, SW6 6JB, UK.
- Cancer Research UK Convergence Science Centre, Roderic Hill Building, Imperial College London, London, SW7 2BB, UK.
| | - Sam H Au
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK
- Cancer Research UK Convergence Science Centre, Roderic Hill Building, Imperial College London, London, SW7 2BB, UK
| | - Chris Bakal
- Division of Cancer Biology, Chester Beatty Laboratories, Institute of Cancer Research, 237 Fulham Road, London, SW6 6JB, UK.
- Cancer Research UK Convergence Science Centre, Roderic Hill Building, Imperial College London, London, SW7 2BB, UK.
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48
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Duarte-Filho GC, Santos FAN, Gaffney EA. Fock-space methods for diffusion: Capturing volume exclusion via fermionic statistics. Phys Rev E 2020; 102:052101. [PMID: 33327117 DOI: 10.1103/physreve.102.052101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 10/13/2020] [Indexed: 11/07/2022]
Abstract
Volume exclusion and single-file diffusion play an important role at very small scales, such as those associated with molecular machines, ion channels, and transport in zeolites, while introducing fundamental differences compared to Brownian motion, such as changes to the power-law relation between the mean square displacement and time. In this work we map the chemical master equation for excluded diffusion onto a Schrödinger equation via annihilation and creation ladder operators with fermionic statistics, together with linear and symbolic algebra with the resulting Fock-space representation to describe the effect of volume-exclusion processes in finite one-dimensional chains. We contrast the dynamics with the nonexclusive (bosonic) diffusion for crowded, intermediate, and dilute particle populations. Motivated by shuttling in molecular machines, we proceed to investigate differences in exit time distributions introduced by volume exclusion, incorporating the presence of transport bias. More generally, this study demonstrates how one can analyze volume-excluded transport for small stochastic systems, without the need for stochastic simulation and ensemble averaging, simply by considering anticommutation relations and fermionic statistics in a Fock-space representation of the stochastic dynamics.
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Affiliation(s)
- Gerson C Duarte-Filho
- Departamento de Física, Universidade Federal de Sergipe, 49100-000 São Cristóvão, Sergipe, Brazil
| | - Fernando A N Santos
- Departamento de Matemática Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil and Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Eamonn A Gaffney
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom
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49
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A biomimetic model of 3D fluid extracellular macromolecular crowding microenvironment fine-tunes ovarian cancer cells dissemination phenotype. Biomaterials 2020; 269:120610. [PMID: 33388691 DOI: 10.1016/j.biomaterials.2020.120610] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/21/2020] [Accepted: 12/14/2020] [Indexed: 12/15/2022]
Abstract
An early fundamental step in ovarian cancer progression is the dissemination of cancer cells through liquid environments, one of them being cancer ascites accumulated in the peritoneal cavity. These biological fluids are highly crowded with a high total macromolecule concentration. This biophysical property of fluids is widely used in tissue engineering for a few decades now, yet is largely underrated in cancer biomimetic models. To unravel the role of fluids extracellular macromolecular crowding (MMC), we exposed ovarian cancer cells (OCC) to high molecular weight inert polymer solutions. High macromolecular composition of extracellular liquid presented a differential effect: i) it impeded non-adherent OCC aggregation in suspension and, decreased their adhesion; ii) it promoted adherent OCC migration by decreasing extracellular matrix deposition. Besides, there seemed to be a direct link between the extracellular MMC and intracellular processes, especially the actin cytoskeleton organization and the nucleus morphology. In conclusion, extracellular fluid MMC orients OCC dissemination phenotype. Integrating MMC seems crucial to produce more relevant mimetic 3D in vitro fluid models to study ovarian dissemination but also to screen drugs.
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50
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Sapra KT, Qin Z, Dubrovsky-Gaupp A, Aebi U, Müller DJ, Buehler MJ, Medalia O. Nonlinear mechanics of lamin filaments and the meshwork topology build an emergent nuclear lamina. Nat Commun 2020; 11:6205. [PMID: 33277502 PMCID: PMC7718915 DOI: 10.1038/s41467-020-20049-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 11/11/2020] [Indexed: 01/16/2023] Open
Abstract
The nuclear lamina—a meshwork of intermediate filaments termed lamins—is primarily responsible for the mechanical stability of the nucleus in multicellular organisms. However, structural-mechanical characterization of lamin filaments assembled in situ remains elusive. Here, we apply an integrative approach combining atomic force microscopy, cryo-electron tomography, network analysis, and molecular dynamics simulations to directly measure the mechanical response of single lamin filaments in three-dimensional meshwork. Endogenous lamin filaments portray non-Hookean behavior – they deform reversibly at a few hundred picoNewtons and stiffen at nanoNewton forces. The filaments are extensible, strong and tough similar to natural silk and superior to the synthetic polymer Kevlar®. Graph theory analysis shows that the lamin meshwork is not a random arrangement of filaments but exhibits small-world properties. Our results suggest that lamin filaments arrange to form an emergent meshwork whose topology dictates the mechanical properties of individual filaments. The quantitative insights imply a role of meshwork topology in laminopathies. Mechanical strength of in situ assembled nuclear lamin filaments arranged in a 3D meshwork is unclear. Here, using mechanical, structural and simulation tools, the authors report the hierarchical organization of the lamin meshwork that imparts strength and toughness to lamin filaments at par with silk and Kevlar®
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Affiliation(s)
- K Tanuj Sapra
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland. .,Department of Biosystems Science and Bioengineering, ETH Zurich, Mattenstrasse 26, 4058, Basel, Switzerland.
| | - Zhao Qin
- Laboratory for Atomistic and Molecular Mechanics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - Anna Dubrovsky-Gaupp
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Ueli Aebi
- Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Bioengineering, ETH Zurich, Mattenstrasse 26, 4058, Basel, Switzerland
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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