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Zhang J, Liang J, Ji D, Shu B, Huang ZS, Li D. Development of a Fluorescent Probe for Specific Visualization of Intracellular DNA i-Motif Participating in Key Biological Function. ACS Sens 2025; 10:3692-3703. [PMID: 40289913 DOI: 10.1021/acssensors.5c00617] [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] [Indexed: 04/30/2025]
Abstract
The i-motif structure has received increasing interest due to its significant biological function discovered in recent years. However, the absence of a handy and efficient method for visualizing the i-motif limited its intracellular study. Herein, we report an innovative coumarin-carbazole-based fluorescent probe, IMCC-6, for intracellular detection of i-motif. IMCC-6 exhibited excellent i-motif recognition ability and selectivity. By using IMCC-6, we successfully visualized the ribosome DNA (rDNA) i-motif within the nucleoli. Our results revealed the colocalization of rDNA i-motif with RNA polymerase I, and their separation under drug-induced nucleolar stress, suggesting that rDNA i-motif could play a regulatory role in rDNA transcription. IMCC-6 was also well applied for the detection of the i-motif in live cells and zebrafish juveniles, which could become an important tool for studying its biological function. As we know, this is the first discovery and development of a small-molecule fluorescent probe for specific visualization of i-motif in cells and in vivo, providing its direct evidence of participating in key biological function.
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Affiliation(s)
- Jiahui Zhang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Wai Huan East Road, Guangzhou 510006, P. R. China
| | - Jihai Liang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Wai Huan East Road, Guangzhou 510006, P. R. China
| | - Dongsheng Ji
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Wai Huan East Road, Guangzhou 510006, P. R. China
| | - Bing Shu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Wai Huan East Road, Guangzhou 510006, P. R. China
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006, P. R. China
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Wai Huan East Road, Guangzhou 510006, P. R. China
| | - Ding Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Wai Huan East Road, Guangzhou 510006, P. R. China
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2
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Lopes-Paciencia S, Ferbeyre G. Increased chromatin accessibility underpins senescence. FEBS J 2025. [PMID: 40387486 DOI: 10.1111/febs.70136] [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: 08/06/2024] [Revised: 01/27/2025] [Accepted: 05/07/2025] [Indexed: 05/20/2025]
Abstract
Senescence is a cellular state induced by various stressors or extracellular signals, but a universal pathway that triggers this process irrespective of the initial stressor has yet to be identified. Recent data indicate that chromatin opening, particularly in the noncoding genome, is a hallmark of cellular senescence. We propose a model in which this increased chromatin accessibility mediated by transcription factors downstream of the senescence-inducing stressors acts as a decisive factor to commit cells toward the senescence fate. Engagement toward senescence is then determined by the balance between mechanisms that increase or decrease chromatin accessibility and can be influenced by modulating the activity of specific histone-modifying complexes. Traits of senescent cells, such as increased nuclear and nucleolar size, the secretion of pro-inflammatory cytokines, reduced rRNA biogenesis, telomere dysfunction, expression of retrotransposons and endogenous retroviruses, as well as DNA damage, can all be attributed to increased chromatin accessibility. This concept suggests potential targets to tilt the balance toward the senescence response in the context of future therapies against cancer and age-related diseases.
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Affiliation(s)
- Stéphane Lopes-Paciencia
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Canada
| | - Gerardo Ferbeyre
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Canada
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3
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do Nascimento Santos TA, da Silva AKF, Cunha KSG, da Costa CBP, da Silva AR, Castro HC, Oliveira NSC. Current advances in cancer immunohistochemistry: a new perspective for the Ki-67 biomarker. Ecancermedicalscience 2025; 19:1863. [PMID: 40492213 PMCID: PMC12146573 DOI: 10.3332/ecancer.2025.1863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2024] [Indexed: 06/11/2025] Open
Abstract
Ki-67 is a cell proliferation biomarker used to evaluate the proliferative activity of neoplasia cells. However, considering its functions on the cell cycle, the standard method seems to be an underused way of evaluating expression, since so far, its analytical validity of Ki-67 remains questionable for its use in personalised therapy. Improvements in the assessment of Ki-67 expression continue to be explored, and recently, a new approach that considers the heterogeneity or variability in staining intensity has emerged as a more improved way than the traditional method. In this review, we bring together what is available in the literature on the biological properties of the protein and highlight how this potential association is promising in the field of personalised medicine.
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Affiliation(s)
- Talita Alves do Nascimento Santos
- Programa de Pós-Graduação em Patologia, Faculdade de Medicina, Hospital Universitário Antônio Pedro, Universidade Federal Fluminense, Niteroi, RJ 24033-900, Brazil
| | - Anna Karoline Fausto da Silva
- Serviço de Anatomia Patológica, Hospital Universitário Antônio Pedro, Universidade Federal Fluminense, Niteroi, RJ 24033-900, Brazil
| | - Karin Soares Gonçalves Cunha
- Departamento de Patologia, Faculdade de Medicina, Hospital Universitário Antônio Pedro, Universidade Federal Fluminense, Niteroi, RJ 24033-900, Brazil
| | - Camila Braz Pereira da Costa
- Diretoria Industrial, Instituto Vital Brazil, Niteroi, RJ 24230-410, Brazil
- LABiEMOL - PPBI - Departamento de Biologia Molecular e Celular, Instituto de Biologia, Universidade Federal Fluminense, Niteroi, RJ 24210-201, Brazil
| | - Aldo Rodrigues da Silva
- Programa de Pós-Graduação em Patologia, Faculdade de Medicina, Hospital Universitário Antônio Pedro, Universidade Federal Fluminense, Niteroi, RJ 24033-900, Brazil
- LABiEMOL - PPBI - Departamento de Biologia Molecular e Celular, Instituto de Biologia, Universidade Federal Fluminense, Niteroi, RJ 24210-201, Brazil
| | - Helena Carla Castro
- Programa de Pós-Graduação em Patologia, Faculdade de Medicina, Hospital Universitário Antônio Pedro, Universidade Federal Fluminense, Niteroi, RJ 24033-900, Brazil
- LABiEMOL - PPBI - Departamento de Biologia Molecular e Celular, Instituto de Biologia, Universidade Federal Fluminense, Niteroi, RJ 24210-201, Brazil
| | - Nathália Silva Carlos Oliveira
- Departamento de Patologia, Faculdade de Medicina, Hospital Universitário Antônio Pedro, Universidade Federal Fluminense, Niteroi, RJ 24033-900, Brazil
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4
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Ataei L, Zhang J, Monis S, Giemza K, Mittal K, Yang J, Shimomura M, McStay B, Wilson MD, Ramalho-Santos M. LINE1 elements at distal junctions of rDNA repeats regulate nucleolar organization in human embryonic stem cells. Genes Dev 2025; 39:280-298. [PMID: 39797762 PMCID: PMC11795452 DOI: 10.1101/gad.351979.124] [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: 06/06/2024] [Accepted: 11/11/2024] [Indexed: 01/13/2025]
Abstract
The nucleolus is a major subnuclear compartment where ribosomal DNA (rDNA) is transcribed and ribosomes are assembled. In addition, recent studies have shown that the nucleolus is a dynamic organizer of chromatin architecture that modulates developmental gene expression. rDNA gene units are assembled into arrays located in the p-arms of five human acrocentric chromosomes. Distal junctions (DJs) are ∼400 kb sequences adjacent to rDNA arrays that are thought to anchor them at the nucleolus, although the underlying regulatory elements remain unclear. Here we show that DJs display a dynamic chromosome conformation profile in human embryonic stem cells (hESCs). We identified a primate-specific, full-length insertion of the retrotransposon long interspersed nuclear element 1 (LINE1) in a conserved position across all human DJs. This DJ-LINE1 locus interacts with specific regions of the DJ and is upregulated in naïve hESCs. CRISPR-based deletion and interference approaches revealed that DJ-LINE1 contributes to nucleolar positioning of the DJs. Moreover, we found that the expression of DJ-LINE1 is required for maintenance of the structure and transcriptional output of the nucleolus in hESCs. Silencing of DJ-LINE1 leads to loss of self-renewal, disruption of the landscape of chromatin accessibility, and derepression of earlier developmental programs in naïve hESCs. This work uncovers specific LINE1 elements with a fundamental role in nucleolar organization in hESCs and provides new insights into how the nucleolus functions as a key genome-organizing hub.
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Affiliation(s)
- Lamisa Ataei
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5T 3H7, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Juan Zhang
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5T 3H7, Canada
| | - Simon Monis
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Genetics and Genome Biology Program, the Hospital for Sick Children (SickKids) Research Institute, Toronto, Ontario M5G 0A4, Canada
| | - Krystyna Giemza
- Centre for Chromosome Biology, College of Science and Engineering, University of Galway, Galway H91 W2TY, Ireland
| | - Kirti Mittal
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5T 3H7, Canada
| | - Joshua Yang
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Mayu Shimomura
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Brian McStay
- Centre for Chromosome Biology, College of Science and Engineering, University of Galway, Galway H91 W2TY, Ireland
| | - Michael D Wilson
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Genetics and Genome Biology Program, the Hospital for Sick Children (SickKids) Research Institute, Toronto, Ontario M5G 0A4, Canada
| | - Miguel Ramalho-Santos
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5T 3H7, Canada;
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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5
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Coulon A. Interphase chromatin biophysics and mechanics: new perspectives and open questions. Curr Opin Genet Dev 2025; 90:102296. [PMID: 39724779 DOI: 10.1016/j.gde.2024.102296] [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: 08/29/2024] [Revised: 11/01/2024] [Accepted: 11/26/2024] [Indexed: 12/28/2024]
Abstract
The physical organization and properties of chromatin within the interphase nucleus are intimately linked to a wide range of functional DNA-based processes. In this context, interphase chromatin mechanics - that is, how chromatin, physically, responds to forces - is gaining increasing attention. Recent methodological advances for probing the force-response of chromatin in cellulo open new avenues for research, as well as new questions. This review discusses emerging views from these approaches and others, including recent in vitro single-molecule studies of cohesin and condensin motor activities, providing insights into physical and material aspects of chromatin, its plasticity in the context of functional processes, its nonequilibrium or 'active matter' properties, and the importance of factors such as chromatin fiber tension and stiffness. This growing field offers exciting opportunities to better understand the interplay between interphase chromosome structure, dynamics, mechanics, and functions.
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Affiliation(s)
- Antoine Coulon
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664 Laboratoire Dynamique du Noyau, CNRS UMR168 Laboratoire Physique des Cellules et Cancer, 75005 Paris, France.
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6
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Soggia G, ElMaghloob Y, Boromangnaeva AK, Al Jord A. Mechanical Remodeling of Nuclear Biomolecular Condensates. Physiology (Bethesda) 2025; 40:0. [PMID: 39109673 DOI: 10.1152/physiol.00027.2024] [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: 06/03/2024] [Revised: 08/05/2024] [Accepted: 08/06/2024] [Indexed: 08/15/2024] Open
Abstract
Organism health relies on cell proliferation, migration, and differentiation. These universal processes depend on cytoplasmic reorganization driven notably by the cytoskeleton and its force-generating motors. Their activity generates forces that mechanically agitate the cell nucleus and its interior. New evidence from reproductive cell biology revealed that these cytoskeletal forces can be tuned to remodel nuclear membraneless compartments, known as biomolecular condensates, and regulate their RNA processing function for the success of subsequent cell division that is critical for fertility. Both cytoskeletal and nuclear condensate reorganization are common to numerous physiological and pathological contexts, raising the possibility that mechanical remodeling of nuclear condensates may be a much broader mechanism regulating their function. Here, we review this newfound mechanism of condensate remodeling and venture into the contexts of health and disease where it may be relevant, with a focus on reproduction, cancer, and premature aging.
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Affiliation(s)
- Giulia Soggia
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
| | - Yasmin ElMaghloob
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain
- Systems Biology and Immunology Lab, Children's Cancer Hospital Egypt, Cairo, Egypt
| | | | - Adel Al Jord
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
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7
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Chawla R, Tom JKA, Boyd T, Tu NH, Bai T, Grotjahn DA, Park D, Deniz AA, Racki LR. Reentrant DNA shells tune polyphosphate condensate size. Nat Commun 2024; 15:9258. [PMID: 39462120 PMCID: PMC11513989 DOI: 10.1038/s41467-024-53469-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 10/11/2024] [Indexed: 10/28/2024] Open
Abstract
The inorganic biopolymer polyphosphate (polyP) occurs in all domains of life and affects myriad cellular processes. A longstanding observation is polyP's frequent proximity to chromatin, and, in many bacteria, its occurrence as magnesium (Mg2+)-enriched condensates embedded in the nucleoid region, particularly in response to stress. The physical basis of the interaction between polyP, DNA and Mg2+, and the resulting effects on the organization of the nucleoid and polyP condensates, remain poorly understood. Here, using a minimal system of polyP, Mg2+, and DNA, we find that DNA can form shells around polyP-Mg2+ condensates. These shells show reentrant behavior, that is, they form within a window of Mg2+ concentrations, representing a tunable architecture with potential relevance in other multicomponent condensates. This surface association tunes condensate size and DNA morphology in a manner dependent on DNA length and concentration, even at DNA concentrations orders of magnitude lower than found in the cell. Our work also highlights the remarkable capacity of two primordial inorganic species to organize DNA.
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Affiliation(s)
- Ravi Chawla
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
- Chakra Techworks Inc., San Diego, CA, USA
| | - Jenna K A Tom
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Tumara Boyd
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Nicholas H Tu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Tanxi Bai
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Danielle A Grotjahn
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Donghyun Park
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Ashok A Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA.
| | - Lisa R Racki
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA.
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8
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Sheu-Gruttadauria J, Yan X, Stuurman N, Vale RD, Floor SN. Nucleolar dynamics are determined by the ordered assembly of the ribosome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.26.559432. [PMID: 37808656 PMCID: PMC10557630 DOI: 10.1101/2023.09.26.559432] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Ribosome biogenesis occurs in the nucleolus, a nuclear biomolecular condensate that exhibits dynamic biophysical properties thought to be important for function. However, the relationship between ribosome assembly and nucleolar dynamics is incompletely understood. Here, we present a platform for high-throughput fluorescence recovery after photobleaching (HiT-FRAP), which we use to screen hundreds of genes for their impact on dynamics of the nucleolar scaffold nucleophosmin (NPM1). We find that scaffold dynamics and nucleolar morphology respond to disruptions in key stages of ribosome biogenesis. Accumulation of early ribosomal intermediates leads to nucleolar rigidification while late intermediates lead to increased fluidity. We map these biophysical changes to specific ribosomal intermediates and their affinity for NPM1. We also discover that disrupting mRNA processing impacts nucleolar dynamics and ribosome biogenesis. This work mechanistically ties ribosome assembly to the biophysical features of the nucleolus and enables study of how dynamics relate to function across other biomolecular condensates.
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Affiliation(s)
- Jessica Sheu-Gruttadauria
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
- Department of Cell and Tissue Biology, University of California, San Francisco, CA, USA
| | - Xiaowei Yan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
- Present address: Department of Dermatology, Stanford, CA, USA
| | - Nico Stuurman
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
- Present address: Altos Labs, Redwood City, CA, USA
| | - Ronald D. Vale
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Stephen N. Floor
- Department of Cell and Tissue Biology, University of California, San Francisco, CA, USA
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
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9
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Strom AR, Kim Y, Zhao H, Chang YC, Orlovsky ND, Košmrlj A, Storm C, Brangwynne CP. Condensate interfacial forces reposition DNA loci and probe chromatin viscoelasticity. Cell 2024; 187:5282-5297.e20. [PMID: 39168125 DOI: 10.1016/j.cell.2024.07.034] [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: 02/27/2023] [Revised: 04/22/2024] [Accepted: 07/19/2024] [Indexed: 08/23/2024]
Abstract
Biomolecular condensates assemble in living cells through phase separation and related phase transitions. An underappreciated feature of these dynamic molecular assemblies is that they form interfaces with other cellular structures, including membranes, cytoskeleton, DNA and RNA, and other membraneless compartments. These interfaces are expected to give rise to capillary forces, but there are few ways of quantifying and harnessing these forces in living cells. Here, we introduce viscoelastic chromatin tethering and organization (VECTOR), which uses light-inducible biomolecular condensates to generate capillary forces at targeted DNA loci. VECTOR can be utilized to programmably reposition genomic loci on a timescale of seconds to minutes, quantitatively revealing local heterogeneity in the viscoelastic material properties of chromatin. These synthetic condensates are built from components that naturally form liquid-like structures in living cells, highlighting the potential role for native condensates to generate forces and do work to reorganize the genome and impact chromatin architecture.
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Affiliation(s)
- Amy R Strom
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Yoonji Kim
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Hongbo Zhao
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Department of Mechanical and Aerospace Engineering, Princeton, NJ 08544, USA; Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ 08544, USA
| | - Yi-Che Chang
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Natalia D Orlovsky
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Andrej Košmrlj
- Department of Mechanical and Aerospace Engineering, Princeton, NJ 08544, USA; Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ 08544, USA; Princeton Materials Institute, Princeton University, Princeton, NJ 08544, USA
| | - Cornelis Storm
- Eindhoven University of Technology, Department of Applied Physics and Science Education, Eindhoven, the Netherlands
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ 08544, USA; Princeton Materials Institute, Princeton University, Princeton, NJ 08544, USA; Howard Hughes Medical Institute, Chevy Chase, MD 21044, USA.
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10
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Deng T, Shao J, Xie Z, Wang Q, Huang X, Zhou Z, Guo J, Li L, Liu F. Triphenylphosphine-bonded coumaranone dyes realize dual color imaging of mitochondria and nucleoli. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 317:124434. [PMID: 38735113 DOI: 10.1016/j.saa.2024.124434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 04/16/2024] [Accepted: 05/07/2024] [Indexed: 05/14/2024]
Abstract
Probing intracellular organelles with fluorescent dyes offers opportunities to understand the structures and functions of these cellular compartments, which is attracting increasing interests. Normally, the design principle varies for different organelle targets as they possess distinct structural and functional profiles against each other. Therefore, developing a probe with dual intracellular targets is of great challenge. In this work, a new sort of donor-π-bridge-acceptor (D-π-A) type coumaranone dyes (CMO-1/2/3/4) have been prepared. Four fluorescent probes (TPP@CMO-1/2/3/4) were then synthesized by linking these coumaranone dyes with an amphiphilic cation triphenylphosphonium (TPP). Interestingly, both TPP@CMO-1 and TPP@CMO-2 exhibited dual color emission upon targeting to two different organelles, respectively. The green emission is well localized in mitochondria, while, the red emission realizes nucleoli imaging. RNA is the target of TPP@CMOs, which was confirmed by spectroscopic analysis and computational calculation. More importantly, the number and morphology changes of nucleoli under drug stress have been successfully evaluated using TPP@CMO-1.
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Affiliation(s)
- Tao Deng
- Artemisinin Research Center, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, China; School of Medicine, Foshan University, Foshan 528000, China
| | - Jinjin Shao
- Artemisinin Research Center, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Zhongguo Xie
- Artemisinin Research Center, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Qiling Wang
- Artemisinin Research Center, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Xinxin Huang
- Artemisinin Research Center, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Zhichao Zhou
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital, Guangzhou Medical University, Guangzhou, 510120, China
| | - Jialiang Guo
- School of Medicine, Foshan University, Foshan 528000, China
| | - Lei Li
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, China.
| | - Fang Liu
- Artemisinin Research Center, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, China.
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11
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Lao Z, Kamat KD, Jiang Z, Zhang B. OpenNucleome for high-resolution nuclear structural and dynamical modeling. eLife 2024; 13:RP93223. [PMID: 39146200 PMCID: PMC11326778 DOI: 10.7554/elife.93223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2024] Open
Abstract
The intricate structural organization of the human nucleus is fundamental to cellular function and gene regulation. Recent advancements in experimental techniques, including high-throughput sequencing and microscopy, have provided valuable insights into nuclear organization. Computational modeling has played significant roles in interpreting experimental observations by reconstructing high-resolution structural ensembles and uncovering organization principles. However, the absence of standardized modeling tools poses challenges for furthering nuclear investigations. We present OpenNucleome-an open-source software designed for conducting GPU-accelerated molecular dynamics simulations of the human nucleus. OpenNucleome offers particle-based representations of chromosomes at a resolution of 100 KB, encompassing nuclear lamina, nucleoli, and speckles. This software furnishes highly accurate structural models of nuclear architecture, affording the means for dynamic simulations of condensate formation, fusion, and exploration of non-equilibrium effects. We applied OpenNucleome to uncover the mechanisms driving the emergence of 'fixed points' within the nucleus-signifying genomic loci robustly anchored in proximity to specific nuclear bodies for functional purposes. This anchoring remains resilient even amidst significant fluctuations in chromosome radial positions and nuclear shapes within individual cells. Our findings lend support to a nuclear zoning model that elucidates genome functionality. We anticipate OpenNucleome to serve as a valuable tool for nuclear investigations, streamlining mechanistic explorations and enhancing the interpretation of experimental observations.
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Affiliation(s)
- Zhuohan Lao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, United States
| | - Kartik D Kamat
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, United States
| | - Zhongling Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, United States
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, United States
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12
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Arsenadze G, Caragine CM, Coakley T, Eshghi I, Yang Y, Wofford A, Zidovska A. Anomalous coarsening of coalescing nucleoli in human cells. Biophys J 2024; 123:1467-1480. [PMID: 38192101 PMCID: PMC11163295 DOI: 10.1016/j.bpj.2024.01.005] [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: 05/31/2023] [Revised: 09/20/2023] [Accepted: 01/03/2024] [Indexed: 01/10/2024] Open
Abstract
Coarsening is a ubiquitous phenomenon in droplet systems near thermodynamic equilibrium-as an increase in droplet size lowers the system's free energy-however, coarsening of droplets in nonequilibrium systems, such as the cell nucleus, is far from understood. Liquid condensates in the cell nucleus, like nucleoli, form by liquid-liquid phase separation and play a key role in the nuclear organization. In human cells, nucleolar droplets are nucleated at the beginning of the cell cycle and coarsen with time by coalescing with each other. Upon coarsening, human nucleoli exhibit an anomalous volume distribution P(V)∼V-1, which cannot be explained by any existing theory. In this work, we investigate physical mechanisms behind the anomalous coarsening of human nucleoli. Using spinning disk confocal microscopy, we simultaneously record dynamic behavior of nucleoli and their surrounding chromatin before their coalescence in live human cells. We find that nucleolar anomalous coarsening persists during the entire cell cycle. We measure chromatin flows and density between and around nucleoli, as well as relative motion of two nucleoli before they coalesce. We find that, before nucleolar coalescence, chromatin concentration decreases in the space between nucleoli and the nucleoli move faster toward each other, resembling an effective depletion attraction between the coalescing nucleoli. Indeed, our computational simulations of nucleolar dynamics show that short-ranged attraction is sufficient to explain the observed anomalous volume distribution of human nucleoli. Overall, our results reveal a potential physical mechanism contributing to coarsening of human nucleoli. Such knowledge expands our picture of the physical behavior of liquid condensates inside the cell nucleus and our understanding of the dynamic nuclear organization.
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Affiliation(s)
- Giorgi Arsenadze
- Center for Soft Matter Research, Department of Physics, New York University, New York, New York
| | - Christina M Caragine
- Center for Soft Matter Research, Department of Physics, New York University, New York, New York
| | - Taylor Coakley
- Center for Soft Matter Research, Department of Physics, New York University, New York, New York
| | - Iraj Eshghi
- Center for Soft Matter Research, Department of Physics, New York University, New York, New York
| | - Yuwei Yang
- Center for Soft Matter Research, Department of Physics, New York University, New York, New York
| | - Alex Wofford
- Center for Soft Matter Research, Department of Physics, New York University, New York, New York
| | - Alexandra Zidovska
- Center for Soft Matter Research, Department of Physics, New York University, New York, New York.
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13
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Zorbas C, Soenmez A, Léger J, De Vleeschouwer C, Lafontaine DL. Detecting material state changes in the nucleolus by label-free digital holographic microscopy. EMBO Rep 2024; 25:2786-2811. [PMID: 38654122 PMCID: PMC11169520 DOI: 10.1038/s44319-024-00134-5] [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: 03/15/2023] [Revised: 03/04/2024] [Accepted: 03/20/2024] [Indexed: 04/25/2024] Open
Abstract
Ribosome biogenesis is initiated in the nucleolus, a multiphase biomolecular condensate formed by liquid-liquid phase separation. The nucleolus is a powerful disease biomarker and stress biosensor whose morphology reflects function. Here we have used digital holographic microscopy (DHM), a label-free quantitative phase contrast microscopy technique, to detect nucleoli in adherent and suspension human cells. We trained convolutional neural networks to detect and quantify nucleoli automatically on DHM images. Holograms containing cell optical thickness information allowed us to define a novel index which we used to distinguish nucleoli whose material state had been modulated optogenetically by blue-light-induced protein aggregation. Nucleoli whose function had been impacted by drug treatment or depletion of ribosomal proteins could also be distinguished. We explored the potential of the technology to detect other natural and pathological condensates, such as those formed upon overexpression of a mutant form of huntingtin, ataxin-3, or TDP-43, and also other cell assemblies (lipid droplets). We conclude that DHM is a powerful tool for quantitatively characterizing nucleoli and other cell assemblies, including their material state, without any staining.
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Affiliation(s)
- Christiane Zorbas
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S./FNRS), Université libre de Bruxelles (ULB), Biopark campus, B-6041, Gosselies, Belgium
| | - Aynur Soenmez
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S./FNRS), Université libre de Bruxelles (ULB), Biopark campus, B-6041, Gosselies, Belgium
| | - Jean Léger
- ICTEAM-ELEN, Fonds de la Recherche Scientifique (F.R.S./FNRS), UCLouvain, B-1348, Louvain-la-Neuve, Belgium
| | - Christophe De Vleeschouwer
- ICTEAM-ELEN, Fonds de la Recherche Scientifique (F.R.S./FNRS), UCLouvain, B-1348, Louvain-la-Neuve, Belgium
| | - Denis Lj Lafontaine
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S./FNRS), Université libre de Bruxelles (ULB), Biopark campus, B-6041, Gosselies, Belgium.
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14
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Ibáñez de Opakua A, Pantoja CF, Cima-Omori MS, Dienemann C, Zweckstetter M. Impact of distinct FG nucleoporin repeats on Nup98 self-association. Nat Commun 2024; 15:3797. [PMID: 38714656 PMCID: PMC11076500 DOI: 10.1038/s41467-024-48194-4] [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: 06/15/2023] [Accepted: 04/24/2024] [Indexed: 05/10/2024] Open
Abstract
Nucleoporins rich in phenylalanine/glycine (FG) residues form the permeability barrier within the nuclear pore complex and are implicated in several pathological cellular processes, including oncogenic fusion condensates. The self-association of FG-repeat proteins and interactions between FG-repeats play a critical role in these activities by forming hydrogel-like structures. Here we show that mutation of specific FG repeats of Nup98 can strongly decrease the protein's self-association capabilities. We further present a cryo-electron microscopy structure of a Nup98 peptide fibril with higher stability per residue compared with previous Nup98 fibril structures. The high-resolution structure reveals zipper-like hydrophobic patches which contain a GLFG motif and are less compatible for binding to nuclear transport receptors. The identified distinct molecular properties of different regions of the nucleoporin may contribute to spatial variations in the self-association of FG-repeats, potentially influencing transport processes through the nuclear pore.
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Affiliation(s)
- Alain Ibáñez de Opakua
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, Göttingen, Germany
| | - Christian F Pantoja
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, Göttingen, Germany
| | - Maria-Sol Cima-Omori
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, Göttingen, Germany
| | - Christian Dienemann
- Max Planck Institute for Multidisciplinary Sciences, Department of Molecular Biology, Am Fassberg 11, Göttingen, Germany
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, Göttingen, Germany.
- Max Planck Institute for Multidisciplinary Sciences, Department of NMR-based Structural Biology, Am Fassberg 11, Göttingen, Germany.
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15
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Lopes-Paciencia S, Bourdeau V, Rowell MC, Amirimehr D, Guillon J, Kalegari P, Barua A, Quoc-Huy Trinh V, Azzi F, Turcotte S, Serohijos A, Ferbeyre G. A senescence restriction point acting on chromatin integrates oncogenic signals. Cell Rep 2024; 43:114044. [PMID: 38568812 DOI: 10.1016/j.celrep.2024.114044] [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: 12/14/2022] [Revised: 02/12/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024] Open
Abstract
We identify a senescence restriction point (SeRP) as a critical event for cells to commit to senescence. The SeRP integrates the intensity and duration of oncogenic stress, keeps a memory of previous stresses, and combines oncogenic signals acting on different pathways by modulating chromatin accessibility. Chromatin regions opened upon commitment to senescence are enriched in nucleolar-associated domains, which are gene-poor regions enriched in repeated sequences. Once committed to senescence, cells no longer depend on the initial stress signal and exhibit a characteristic transcriptome regulated by a transcription factor network that includes ETV4, RUNX1, OCT1, and MAFB. Consistent with a tumor suppressor role for this network, the levels of ETV4 and RUNX1 are very high in benign lesions of the pancreas but decrease dramatically in pancreatic ductal adenocarcinomas. The discovery of senescence commitment and its chromatin-linked regulation suggests potential strategies for reinstating tumor suppression in human cancers.
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Affiliation(s)
- Stéphane Lopes-Paciencia
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada
| | - Véronique Bourdeau
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Marie-Camille Rowell
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada
| | - Davoud Amirimehr
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Jordan Guillon
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada
| | - Paloma Kalegari
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada
| | - Arnab Barua
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Vincent Quoc-Huy Trinh
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada; Institut de recherche en immunologie et en cancérologie (IRIC), Université de Montréal, Montréal, QC H3C 3J7, Canada; Département de pathologie, Centre hospitalier de l'Université de Montréal, Montréal, QC, Canada
| | - Feryel Azzi
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada
| | - Simon Turcotte
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada; Département de chirurgie, Service de chirurgie hépatopancréatobiliaire, Centre hospitalier de l'Université de Montréal, Montréal, QC, Canada
| | - Adrian Serohijos
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Gerardo Ferbeyre
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC H2X 0A9, Canada; Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3C 3J7, Canada.
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16
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Wu ZP, Bloom KS, Forest MG, Cao XZ. Transient crosslinking controls the condensate formation pathway within chromatin networks. Phys Rev E 2024; 109:L042401. [PMID: 38755828 PMCID: PMC11137846 DOI: 10.1103/physreve.109.l042401] [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: 09/10/2023] [Accepted: 02/26/2024] [Indexed: 05/18/2024]
Abstract
The network structure of densely packed chromatin within the nucleus of eukaryotic cells acts in concert with nonequilibrium processes. Using statistical physics simulations, we explore the control provided by transient crosslinking of the chromatin network by structural-maintenance-of-chromosome (SMC) proteins over (i) the physical properties of the chromatin network and (ii) condensate formation of embedded molecular species. We find that the density and lifetime of transient SMC crosslinks regulate structural relaxation modes and tune the sol-vs-gel state of the chromatin network, which imparts control over the kinetic pathway to condensate formation. Specifically, lower density, shorter-lived crosslinks induce sollike networks and a droplet-fusion pathway, whereas higher density, longer-lived crosslinks induce gellike networks and an Ostwald-ripening pathway.
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Affiliation(s)
- Zong-Pei Wu
- Department of Physics at Xiamen University, Xiamen 361005, P.R. China
| | - Kerry S. Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - M. Gregory Forest
- Departments of Mathematics, Applied Physical Sciences and Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Xue-Zheng Cao
- Department of Physics at Xiamen University, Xiamen 361005, P.R. China
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17
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Jiang W, Qiao Q, Chen J, Bao P, Tao Y, Zhang Y, Xu Z. Rna Buffering Fluorogenic Probe for Nucleolar Morphology Stable Imaging And Nucleolar Stress-Generating Agents Screening. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2309743. [PMID: 38326089 PMCID: PMC11022735 DOI: 10.1002/advs.202309743] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/22/2024] [Indexed: 02/09/2024]
Abstract
In the realm of cell research, membraneless organelles have become a subject of increasing interest. However, their ever-changing and amorphous morphological characteristics have long presented a formidable challenge when it comes to studying their structure and function. In this paper, a fluorescent probe Nu-AN is reported, which exhibits the remarkable capability to selectively bind to and visualize the nucleolus morphology, the largest membraneless organelle within the nucleus. Nu-AN demonstrates a significant enhancement in fluorescence upon its selective binding to nucleolar RNA, due to the inhibited twisted intramolecular charge-transfer (TICT) and reduced hydrogen bonding with water. What sets Nu-AN apart is its neutral charge and weak interaction with nucleolus RNA, enabling it to label the nucleolus selectively and reversibly. This not only reduces interference but also permits the replacement of photobleached probes with fresh ones outside the nucleolus, thereby preserving imaging photostability. By closely monitoring morphology-specific changes in the nucleolus with this buffering fluorogenic probe, screenings for agents are conducted that induce nucleolar stress within living cells.
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Affiliation(s)
- Wenchao Jiang
- CAS Key Laboratory of Separation Science for Analytical ChemistryDalian Institute of Chemical PhysicsChinese Academy of Sciences457 Zhongshan RoadDalian116023China
- University of Chinese Academy of SciencesBeijing100049China
| | - Qinglong Qiao
- CAS Key Laboratory of Separation Science for Analytical ChemistryDalian Institute of Chemical PhysicsChinese Academy of Sciences457 Zhongshan RoadDalian116023China
| | - Jie Chen
- CAS Key Laboratory of Separation Science for Analytical ChemistryDalian Institute of Chemical PhysicsChinese Academy of Sciences457 Zhongshan RoadDalian116023China
- University of Chinese Academy of SciencesBeijing100049China
| | - Pengjun Bao
- CAS Key Laboratory of Separation Science for Analytical ChemistryDalian Institute of Chemical PhysicsChinese Academy of Sciences457 Zhongshan RoadDalian116023China
- University of Chinese Academy of SciencesBeijing100049China
| | - Yi Tao
- CAS Key Laboratory of Separation Science for Analytical ChemistryDalian Institute of Chemical PhysicsChinese Academy of Sciences457 Zhongshan RoadDalian116023China
- University of Chinese Academy of SciencesBeijing100049China
| | - Yinchan Zhang
- CAS Key Laboratory of Separation Science for Analytical ChemistryDalian Institute of Chemical PhysicsChinese Academy of Sciences457 Zhongshan RoadDalian116023China
- University of Chinese Academy of SciencesBeijing100049China
| | - Zhaochao Xu
- CAS Key Laboratory of Separation Science for Analytical ChemistryDalian Institute of Chemical PhysicsChinese Academy of Sciences457 Zhongshan RoadDalian116023China
- University of Chinese Academy of SciencesBeijing100049China
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18
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Lao Z, Kamat K, Jiang Z, Zhang B. OpenNucleome for high resolution nuclear structural and dynamical modeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.16.562451. [PMID: 37905090 PMCID: PMC10614770 DOI: 10.1101/2023.10.16.562451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
The intricate structural organization of the human nucleus is fundamental to cellular function and gene regulation. Recent advancements in experimental techniques, including high-throughput sequencing and microscopy, have provided valuable insights into nuclear organization. Computational modeling has played significant roles in interpreting experimental observations by reconstructing high-resolution structural ensembles and uncovering organization principles. However, the absence of standardized modeling tools poses challenges for furthering nuclear investigations. We present OpenNucleome-an open-source software designed for conducting GPU-accelerated molecular dynamics simulations of the human nucleus. OpenNucleome offers particle-based representations of chromosomes at a resolution of 100 KB, encompassing nuclear lamina, nucleoli, and speckles. This software furnishes highly accurate structural models of nuclear architecture, affording the means for dynamic simulations of condensate formation, fusion, and exploration of non-equilibrium effects. We applied OpenNucleome to uncover the mechanisms driving the emergence of "fixed points" within the nucleus-signifying genomic loci robustly anchored in proximity to specific nuclear bodies for functional purposes. This anchoring remains resilient even amidst significant fluctuations in chromosome radial positions and nuclear shapes within individual cells. Our findings lend support to a nuclear zoning model that elucidates genome functionality. We anticipate OpenNucleome to serve as a valuable tool for nuclear investigations, streamlining mechanistic explorations and enhancing the interpretation of experimental observations.
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Affiliation(s)
- Zhuohan Lao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kartik Kamat
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Zhongling Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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19
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Meng L, Mao S, Lin J. Heterogeneous elasticity drives ripening and controls bursting kinetics of transcriptional condensates. Proc Natl Acad Sci U S A 2024; 121:e2316610121. [PMID: 38489385 PMCID: PMC10962985 DOI: 10.1073/pnas.2316610121] [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: 09/24/2023] [Accepted: 02/10/2024] [Indexed: 03/17/2024] Open
Abstract
Many biomolecular condensates, including transcriptional condensates, are formed in elastic mediums. In this work, we study the nonequilibrium condensate dynamics in a chromatin-like environment modeled as a heterogeneous elastic medium. We demonstrate that the ripening process in such an elastic medium exhibits a temporal power-law scaling of the average condensate radius, depending on the local stiffness distribution and different from Ostwald ripening. Moreover, we incorporate an active process to model the dissolution of transcriptional condensates upon RNA accumulation. Intriguingly, three types of kinetics of condensate growth emerge, corresponding to constitutively expressed, transcriptional-bursting, and silenced genes. Furthermore, the simulated burst frequency decreases exponentially with the local stiffness, through which we infer a lognormal distribution of local stiffness in living cells using the transcriptome-wide distribution of burst frequency. Under the inferred stiffness distribution, the simulated distributions of bursting kinetic parameters agree reasonably well with the experimental data. Our findings reveal the interplay between biomolecular condensates and elastic mediums, yielding far-reaching implications for gene expression.
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Affiliation(s)
- Lingyu Meng
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Sheng Mao
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing100871, China
| | - Jie Lin
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
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20
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Pham AT, Mani M, Wang X, Vafabakhsh R. Multiscale biophysical analysis of nucleolus disassembly during mitosis. Proc Natl Acad Sci U S A 2024; 121:e2312250121. [PMID: 38285946 PMCID: PMC10861868 DOI: 10.1073/pnas.2312250121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 01/01/2024] [Indexed: 01/31/2024] Open
Abstract
During cell division, precise and regulated distribution of cellular material between daughter cells is a critical step and is governed by complex biochemical and biophysical mechanisms. To achieve this, membraneless organelles and condensates often require complete disassembly during mitosis. The biophysical principles governing the disassembly of condensates remain poorly understood. Here, we used a physical biology approach to study how physical and material properties of the nucleolus, a prominent nuclear membraneless organelle in eukaryotic cells, change during mitosis and across different scales. We found that nucleolus disassembly proceeds continuously through two distinct phases with a slow and reversible preparatory phase followed by a rapid irreversible phase that was concurrent with the nuclear envelope breakdown. We measured microscopic properties of nucleolar material including effective diffusion rates and binding affinities as well as key macroscopic properties of surface tension and bending rigidity. By incorporating these measurements into the framework of critical phenomena, we found evidence that near mitosis surface tension displays a power-law behavior as a function of biochemically modulated interaction strength. This two-step disassembly mechanism maintains structural and functional stability of nucleolus while enabling its rapid and efficient disassembly in response to cell cycle cues.
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Affiliation(s)
- An T. Pham
- Department of Molecular Biosciences, Northwestern University, Evanston, IL60208
| | - Madhav Mani
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL60208
- NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL60208
| | - Xiaozhong Wang
- Department of Molecular Biosciences, Northwestern University, Evanston, IL60208
- NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL60208
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL60208
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21
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Bonucci M, Shu T, Holt LJ. How it feels in a cell. Trends Cell Biol 2023; 33:924-938. [PMID: 37286396 PMCID: PMC10592589 DOI: 10.1016/j.tcb.2023.05.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/01/2023] [Accepted: 05/02/2023] [Indexed: 06/09/2023]
Abstract
Life emerges from thousands of biochemical processes occurring within a shared intracellular environment. We have gained deep insights from in vitro reconstitution of isolated biochemical reactions. However, the reaction medium in test tubes is typically simple and diluted. The cell interior is far more complex: macromolecules occupy more than a third of the space, and energy-consuming processes agitate the cell interior. Here, we review how this crowded, active environment impacts the motion and assembly of macromolecules, with an emphasis on mesoscale particles (10-1000 nm diameter). We describe methods to probe and analyze the biophysical properties of cells and highlight how changes in these properties can impact physiology and signaling, and potentially contribute to aging, and diseases, including cancer and neurodegeneration.
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Affiliation(s)
- Martina Bonucci
- Institute for Systems Genetics, New York University Langone Medical Center, 435 E 30th Street, New York, NY 10016, USA
| | - Tong Shu
- Institute for Systems Genetics, New York University Langone Medical Center, 435 E 30th Street, New York, NY 10016, USA
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Medical Center, 435 E 30th Street, New York, NY 10016, USA.
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22
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Pham AT, Mani M, Wang XA, Vafabakhsh R. The Physical Biology of Nucleolus Disassembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.27.559731. [PMID: 37808669 PMCID: PMC10557732 DOI: 10.1101/2023.09.27.559731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
During cell division, precise and regulated distribution of cellular material between daughter cells is a critical step and is governed by complex biochemical and biophysical mechanisms. To achieve this, membraneless organelles and condensates often require complete disassembly during mitosis. The biophysical principles governing the disassembly of condensates remain poorly understood. Here, we used a physical biology approach to study how physical and material properties of the nucleolus, a prominent nuclear membraneless organelle in eukaryotic cells, change during mitosis and across different scales. We found that nucleolus disassembly proceeds continuously through two distinct phases with a slow and reversible preparatory phase followed by a rapid irreversible phase that was concurrent with the nuclear envelope breakdown. We measured microscopic properties of nucleolar material including effective diffusion rates and binding affinities as well as key macroscopic properties of surface tension and bending rigidity. By incorporating these measurements into the framework of critical phenomena, we found evidence that near mitosis surface tension displays a power-law behavior as a function of biochemically modulated interaction strength. This two-step disassembly mechanism, which maintains structural and functional stability of nucleolus while allowing for its rapid and efficient disassembly in response to cell cycle cues, may be a universal design principle for the disassembly of other biomolecular condensates.
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Affiliation(s)
- An T. Pham
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Madhav Mani
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA
- NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL 60208, USA
| | - Xiaozhong A. Wang
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
- NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL 60208, USA
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
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23
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Chawla R, Tom JKA, Boyd T, Grotjahn DA, Park D, Deniz AA, Racki LR. Reentrant DNA shells tune polyphosphate condensate size. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.13.557044. [PMID: 37745474 PMCID: PMC10515899 DOI: 10.1101/2023.09.13.557044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The ancient, inorganic biopolymer polyphosphate (polyP) occurs in all three domains of life and affects myriad cellular processes. An intriguing feature of polyP is its frequent proximity to chromatin, and in the case of many bacteria, its occurrence in the form of magnesium-enriched condensates embedded in the nucleoid, particularly in response to stress. The physical basis of the interaction between polyP and DNA, two fundamental anionic biopolymers, and the resulting effects on the organization of both the nucleoid and polyP condensates remain poorly understood. Given the essential role of magnesium ions in the coordination of polymeric phosphate species, we hypothesized that a minimal system of polyP, magnesium ions, and DNA (polyP-Mg2+-DNA) would capture key features of the interplay between the condensates and bacterial chromatin. We find that DNA can profoundly affect polyP-Mg2+ coacervation even at concentrations several orders of magnitude lower than found in the cell. The DNA forms shells around polyP-Mg2+ condensates and these shells show reentrant behavior, primarily forming in the concentration range close to polyP-Mg2+ charge neutralization. This surface association tunes both condensate size and DNA morphology in a manner dependent on DNA properties, including length and concentration. Our work identifies three components that could form the basis of a central and tunable interaction hub that interfaces with cellular interactors. These studies will inform future efforts to understand the basis of polyP granule composition and consolidation, as well as the potential capacity of these mesoscale assemblies to remodel chromatin in response to diverse stressors at different length and time scales.
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Affiliation(s)
| | | | - Tumara Boyd
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Danielle A. Grotjahn
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Donghyun Park
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Ashok A. Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Lisa R. Racki
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
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24
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Riback JA, Eeftens JM, Lee DSW, Quinodoz SA, Donlic A, Orlovsky N, Wiesner L, Beckers L, Becker LA, Strom AR, Rana U, Tolbert M, Purse BW, Kleiner R, Kriwacki R, Brangwynne CP. Viscoelasticity and advective flow of RNA underlies nucleolar form and function. Mol Cell 2023; 83:3095-3107.e9. [PMID: 37683610 PMCID: PMC11089468 DOI: 10.1016/j.molcel.2023.08.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 04/20/2023] [Accepted: 08/08/2023] [Indexed: 09/10/2023]
Abstract
The nucleolus is the largest biomolecular condensate and facilitates transcription, processing, and assembly of ribosomal RNA (rRNA). Although nucleolar function is thought to require multiphase liquid-like properties, nucleolar fluidity and its connection to the highly coordinated transport and biogenesis of ribosomal subunits are poorly understood. Here, we use quantitative imaging, mathematical modeling, and pulse-chase nucleotide labeling to examine nucleolar material properties and rRNA dynamics. The mobility of rRNA is several orders of magnitude slower than that of nucleolar proteins, with rRNA steadily moving away from the transcriptional sites in a slow (∼1 Å/s), radially directed fashion. This constrained but directional mobility, together with polymer physics-based calculations, suggests that nascent rRNA forms an entangled gel, whose constant production drives outward flow. We propose a model in which progressive maturation of nascent rRNA reduces its initial entanglement, fluidizing the nucleolar periphery to facilitate the release of assembled pre-ribosomal particles.
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Affiliation(s)
- Joshua A Riback
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Jorine M Eeftens
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Daniel S W Lee
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, Princeton, NJ 08544, USA
| | - Sofia A Quinodoz
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Anita Donlic
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Natalia Orlovsky
- Department of Molecular Biology, Princeton University, Princeton, Princeton, NJ 08544, USA
| | - Lennard Wiesner
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Lien Beckers
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Howard Hughes Medical Institute, Princeton University, Princeton, Princeton, NJ 08544, USA
| | - Lindsay A Becker
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Howard Hughes Medical Institute, Princeton University, Princeton, Princeton, NJ 08544, USA
| | - Amy R Strom
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Ushnish Rana
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Michele Tolbert
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38103, USA
| | - Byron W Purse
- Department of Chemistry and Biochemistry and the Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Ralph Kleiner
- Department of Chemistry, Princeton University, Princeton, Princeton, NJ 08544, USA
| | - Richard Kriwacki
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38103, USA
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, Princeton, NJ 08544, USA; Howard Hughes Medical Institute, Princeton University, Princeton, Princeton, NJ 08544, USA; Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ 08544, USA.
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25
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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: 6] [Impact Index Per Article: 3.0] [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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26
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Hernández‐Carralero E, Cabrera E, Rodríguez-Torres G, Hernández-Reyes Y, Singh A, Santa-María C, Fernández-Justel J, Janssens R, Marteijn J, Evert B, Mailand N, Gómez M, Ramadan K, Smits VJ, Freire R. ATXN3 controls DNA replication and transcription by regulating chromatin structure. Nucleic Acids Res 2023; 51:5396-5413. [PMID: 36971114 PMCID: PMC10287915 DOI: 10.1093/nar/gkad212] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 02/10/2023] [Accepted: 03/14/2023] [Indexed: 11/18/2023] Open
Abstract
The deubiquitinating enzyme Ataxin-3 (ATXN3) contains a polyglutamine (PolyQ) region, the expansion of which causes spinocerebellar ataxia type-3 (SCA3). ATXN3 has multiple functions, such as regulating transcription or controlling genomic stability after DNA damage. Here we report the role of ATXN3 in chromatin organization during unperturbed conditions, in a catalytic-independent manner. The lack of ATXN3 leads to abnormalities in nuclear and nucleolar morphology, alters DNA replication timing and increases transcription. Additionally, indicators of more open chromatin, such as increased mobility of histone H1, changes in epigenetic marks and higher sensitivity to micrococcal nuclease digestion were detected in the absence of ATXN3. Interestingly, the effects observed in cells lacking ATXN3 are epistatic to the inhibition or lack of the histone deacetylase 3 (HDAC3), an interaction partner of ATXN3. The absence of ATXN3 decreases the recruitment of endogenous HDAC3 to the chromatin, as well as the HDAC3 nuclear/cytoplasm ratio after HDAC3 overexpression, suggesting that ATXN3 controls the subcellular localization of HDAC3. Importantly, the overexpression of a PolyQ-expanded version of ATXN3 behaves as a null mutant, altering DNA replication parameters, epigenetic marks and the subcellular distribution of HDAC3, giving new insights into the molecular basis of the disease.
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Affiliation(s)
- Esperanza Hernández‐Carralero
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Elisa Cabrera
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
| | - Gara Rodríguez-Torres
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Yeray Hernández-Reyes
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Abhay N Singh
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Cristina Santa-María
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - José Miguel Fernández-Justel
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - Roel C Janssens
- Department of Molecular Genetics, Oncode Institute, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Jurgen A Marteijn
- Department of Molecular Genetics, Oncode Institute, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Bernd O Evert
- Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Niels Mailand
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - María Gómez
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - Kristijan Ramadan
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Veronique A J Smits
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
- Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
| | - Raimundo Freire
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
- Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
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27
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Ma Q, Huang F, Guo W, Feng K, Huang T, Cai Y. Identification of Phase-Separation-Protein-Related Function Based on Gene Ontology by Using Machine Learning Methods. Life (Basel) 2023; 13:1306. [PMID: 37374089 DOI: 10.3390/life13061306] [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: 03/23/2023] [Revised: 05/06/2023] [Accepted: 05/30/2023] [Indexed: 06/29/2023] Open
Abstract
Phase-separation proteins (PSPs) are a class of proteins that play a role in the process of liquid-liquid phase separation, which is a mechanism that mediates the formation of membranelle compartments in cells. Identifying phase separation proteins and their associated function could provide insights into cellular biology and the development of diseases, such as neurodegenerative diseases and cancer. Here, PSPs and non-PSPs that have been experimentally validated in earlier studies were gathered as positive and negative samples. Each protein's corresponding Gene Ontology (GO) terms were extracted and used to create a 24,907-dimensional binary vector. The purpose was to extract essential GO terms that can describe essential functions of PSPs and build efficient classifiers to identify PSPs with these GO terms at the same time. To this end, the incremental feature selection computational framework and an integrated feature analysis scheme, containing categorical boosting, least absolute shrinkage and selection operator, light gradient-boosting machine, extreme gradient boosting, and permutation feature importance, were used to build efficient classifiers and identify GO terms with classification-related importance. A set of random forest (RF) classifiers with F1 scores over 0.960 were established to distinguish PSPs from non-PSPs. A number of GO terms that are crucial for distinguishing between PSPs and non-PSPs were found, including GO:0003723, which is related to a biological process involving RNA binding; GO:0016020, which is related to membrane formation; and GO:0045202, which is related to the function of synapses. This study offered recommendations for future research aimed at determining the functional roles of PSPs in cellular processes by developing efficient RF classifiers and identifying the representative GO terms related to PSPs.
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Affiliation(s)
- Qinglan Ma
- School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - FeiMing Huang
- School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Wei Guo
- Key Laboratory of Stem Cell Biology, Shanghai Jiao Tong University School of Medicine (SJTUSM) & Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS), Shanghai 200030, China
| | - KaiYan Feng
- Department of Computer Science, Guangdong AIB Polytechnic College, Guangzhou 510507, China
| | - Tao Huang
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yudong Cai
- School of Life Sciences, Shanghai University, Shanghai 200444, China
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28
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Pham DQH, Chwastyk M, Cieplak M. The coexistence region in the Van der Waals fluid and the liquid-liquid phase transitions. Front Chem 2023; 10:1106599. [PMID: 36760519 PMCID: PMC9905123 DOI: 10.3389/fchem.2022.1106599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/29/2022] [Indexed: 01/26/2023] Open
Abstract
Cellular membraneless organelles are thought to be droplets formed within the two-phase region corresponding to proteinaceous systems endowed with the liquid-liquid transition. However, their metastability requires an additional constraint-they arise in a certain region of density and temperature between the spinodal and binodal lines. Here, we consider the well-studied van der Waals fluid as a test model to work out criteria to determine the location of the spinodal line for situations in which the equation of state is not known. Our molecular dynamics studies indicate that this task can be accomplished by considering the specific heat, the surface tension and characteristics of the molecular clusters, such as the number of component chains and radius of gyration.
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Affiliation(s)
| | - Mateusz Chwastyk
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
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29
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Chen P, Levy DL. Regulation of organelle size and organization during development. Semin Cell Dev Biol 2023; 133:53-64. [PMID: 35148938 PMCID: PMC9357868 DOI: 10.1016/j.semcdb.2022.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/20/2022] [Accepted: 02/01/2022] [Indexed: 12/11/2022]
Abstract
During early embryogenesis, as cells divide in the developing embryo, the size of intracellular organelles generally decreases to scale with the decrease in overall cell size. Organelle size scaling is thought to be important to establish and maintain proper cellular function, and defective scaling may lead to impaired development and disease. However, how the cell regulates organelle size and organization are largely unanswered questions. In this review, we summarize the process of size scaling at both the cell and organelle levels and discuss recently discovered mechanisms that regulate this process during early embryogenesis. In addition, we describe how some recently developed techniques and Xenopus as an animal model can be used to investigate the underlying mechanisms of size regulation and to uncover the significance of proper organelle size scaling and organization.
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Affiliation(s)
- Pan Chen
- Institute of Biochemistry and Molecular Biology, School of Medicine, Ningbo University, Ningbo, Zhejiang 315211, China.
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA.
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30
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Jin X, Tanaka H, Jin M, Fujita K, Homma H, Inotsume M, Yong H, Umeda K, Kodera N, Ando T, Okazawa H. PQBP5/NOL10 maintains and anchors the nucleolus under physiological and osmotic stress conditions. Nat Commun 2023; 14:9. [PMID: 36599853 PMCID: PMC9813255 DOI: 10.1038/s41467-022-35602-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Polyglutamine binding protein 5 (PQBP5), also called nucleolar protein 10 (NOL10), binds to polyglutamine tract sequences and is expressed in the nucleolus. Using dynamic imaging of high-speed atomic force microscopy, we show that PQBP5/NOL10 is an intrinsically disordered protein. Super-resolution microscopy and correlative light and electron microscopy method show that PQBP5/NOL10 makes up the skeletal structure of the nucleolus, constituting the granule meshwork in the granular component area, which is distinct from other nucleolar substructures, such as the fibrillar center and dense fibrillar component. In contrast to other nucleolar proteins, which disperse to the nucleoplasm under osmotic stress conditions, PQBP5/NOL10 remains in the nucleolus and functions as an anchor for reassembly of other nucleolar proteins. Droplet and thermal shift assays show that the biophysical features of PQBP5/NOL10 remain stable under stress conditions, explaining the spatial role of this protein. PQBP5/NOL10 can be functionally depleted by sequestration with polyglutamine disease proteins in vitro and in vivo, leading to the pathological deformity or disappearance of the nucleolus. Taken together, these findings indicate that PQBP5/NOL10 is an essential protein needed to maintain the structure of the nucleolus.
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Affiliation(s)
- Xiaocen Jin
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Hikari Tanaka
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Meihua Jin
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Kyota Fujita
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Hidenori Homma
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Maiko Inotsume
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Huang Yong
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Kenichi Umeda
- Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Noriyuki Kodera
- Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Toshio Ando
- Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Hitoshi Okazawa
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
- Center for Brain Integration Research, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
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31
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Lee DSW, Choi CH, Sanders DW, Beckers L, Riback JA, Brangwynne CP, Wingreen NS. Size distributions of intracellular condensates reflect competition between coalescence and nucleation. NATURE PHYSICS 2023; 19:586-596. [PMID: 37073403 PMCID: PMC10104779 DOI: 10.1038/s41567-022-01917-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 12/12/2022] [Indexed: 05/03/2023]
Abstract
Phase separation of biomolecules into condensates has emerged as a mechanism for intracellular organization and affects many intracellular processes, including reaction pathways through the clustering of enzymes and pathway intermediates. Precise and rapid spatiotemporal control of reactions by condensates requires tuning of their sizes. However, the physical processes that govern the distribution of condensate sizes remain unclear. Here we show that both native and synthetic condensates display an exponential size distribution, which is captured by Monte Carlo simulations of fast nucleation followed by coalescence. In contrast, pathological aggregates exhibit a power-law size distribution. These distinct behaviours reflect the relative importance of nucleation and coalescence kinetics. We demonstrate this by utilizing a combination of synthetic and native condensates to probe the underlying physical mechanisms determining condensate size. The appearance of exponential distributions for abrupt nucleation versus power-law distributions under continuous nucleation may reflect a general principle that determines condensate size distributions.
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Affiliation(s)
- Daniel S. W. Lee
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ USA
- Present Address: Department of Bioengineering, University of California, Berkeley, CA USA
| | - Chang-Hyun Choi
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
| | - David W. Sanders
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
| | - Lien Beckers
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
- Howard Hughes Medical Institute, Princeton, NJ USA
| | - Joshua A. Riback
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
- Present Address: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX USA
| | - Clifford P. Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
- Howard Hughes Medical Institute, Princeton, NJ USA
| | - Ned S. Wingreen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ USA
- Department of Molecular Biology, Princeton University, Princeton, NJ USA
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32
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Dutta T, Das S, Gupta I, Koner AL. Construing the metaxin-2 mediated simultaneous localization between mitochondria and nucleolus using molecular viscometry. Chem Sci 2022; 13:12987-12995. [PMID: 36425508 PMCID: PMC9668072 DOI: 10.1039/d2sc03587a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/06/2022] [Indexed: 11/02/2023] Open
Abstract
Fluorescent probes for specific inter-organelle communication are of massive significance as such communication is essential for a diverse range of cellular events. Here, we present the microviscosity-sensitive fluorescence marker, Quinaldine Red (QR), and its dual organelle targeting light-up response in live cells. This biocompatible probe was able to localize in mitochondria and nucleolus simultaneously. While QR was able to sense the viscosity change inside these compartments under the induced effect of an ionophore and ROS-rich microenvironment, the probe's ability to stain mitochondria remained unperturbed even after protonophore-induced depolarization. Consequently, a systematic quantification was performed to understand the alteration of microviscosity. Similar behavior in two distinct organelles implied that QR binds to metaxin-2 protein, common to mitochondrial and nucleolar proteomes. We believe this is the first of its kind investigation that identifies the inter-organelle communications marker and opens up a new dimension in this field.
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Affiliation(s)
- Tanoy Dutta
- Bionanotechnology Lab, Department of Chemistry, Indian Institute of Science Education and Research Bhopal Bhopal Bypass Road, Bhauri Bhopal Madhya Pradesh-462066 India
| | - Sreeparna Das
- Bionanotechnology Lab, Department of Chemistry, Indian Institute of Science Education and Research Bhopal Bhopal Bypass Road, Bhauri Bhopal Madhya Pradesh-462066 India
| | - Ishaan Gupta
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi Hauz Khas New Delhi-110016 India
| | - Apurba Lal Koner
- Bionanotechnology Lab, Department of Chemistry, Indian Institute of Science Education and Research Bhopal Bhopal Bypass Road, Bhauri Bhopal Madhya Pradesh-462066 India
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33
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Yewdall NA, André AAM, van Haren MHI, Nelissen FHT, Jonker A, Spruijt E. ATP:Mg 2+ shapes material properties of protein-RNA condensates and their partitioning of clients. Biophys J 2022; 121:3962-3974. [PMID: 36004782 PMCID: PMC9674983 DOI: 10.1016/j.bpj.2022.08.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/29/2022] [Accepted: 08/19/2022] [Indexed: 11/26/2022] Open
Abstract
Many cellular condensates are heterotypic mixtures of proteins and RNA formed in complex environments. Magnesium ions (Mg2+) and ATP can impact RNA folding, and local intracellular levels of these factors can vary significantly. However, the effect of ATP:Mg2+ on the material properties of protein-RNA condensates is largely unknown. Here, we use an in vitro condensate model of nucleoli, made from nucleophosmin 1 (NPM1) proteins and ribosomal RNA (rRNA), to study the effect of ATP:Mg2+. While NPM1 dynamics remain unchanged at increasing Mg2+ concentrations, the internal RNA dynamics dramatically slowed until a critical point, where gel-like states appeared, suggesting the RNA component alone forms a viscoelastic network that undergoes maturation driven by weak multivalent interactions. ATP reverses this arrest and liquefies the gel-like structures. ATP:Mg2+ also influenced the NPM1-rRNA composition of condensates and enhanced the partitioning of two clients: an arginine-rich peptide and a small nuclear RNA. By contrast, larger ribosome partitioning shows dependence on ATP:Mg2+ and can become reversibly trapped around NPM1-rRNA condensates. Lastly, we show that dissipative enzymatic reactions that deplete ATP can be used to control the shape, composition, and function of condensates. Our results illustrate how intracellular environments may regulate the state and client partitioning of RNA-containing condensates.
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Affiliation(s)
- N Amy Yewdall
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands.
| | - Alain A M André
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands
| | - Merlijn H I van Haren
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands
| | - Frank H T Nelissen
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands
| | - Aafke Jonker
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands
| | - Evan Spruijt
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands.
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34
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Adkins R, Kolvin I, You Z, Witthaus S, Marchetti MC, Dogic Z. Dynamics of active liquid interfaces. Science 2022; 377:768-772. [PMID: 35951710 DOI: 10.1126/science.abo5423] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Controlling interfaces of phase-separating fluid mixtures is key to the creation of diverse functional soft materials. Traditionally, this is accomplished with surface-modifying chemical agents. Using experiment and theory, we studied how mechanical activity shapes soft interfaces that separate an active and a passive fluid. Chaotic flows in the active fluid give rise to giant interfacial fluctuations and noninertial propagating active waves. At high activities, stresses disrupt interface continuity and drive droplet generation, producing an emulsion-like active state composed of finite-sized droplets. When in contact with a solid boundary, active interfaces exhibit nonequilibrium wetting transitions, in which the fluid climbs the wall against gravity. These results demonstrate the promise of mechanically driven interfaces for creating a new class of soft active matter.
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Affiliation(s)
- Raymond Adkins
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Itamar Kolvin
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Zhihong You
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Sven Witthaus
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - M Cristina Marchetti
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.,Graduate program in Biomolecular Science and Engineering, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Zvonimir Dogic
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.,Graduate program in Biomolecular Science and Engineering, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
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35
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Keizer VIP, Grosse-Holz S, Woringer M, Zambon L, Aizel K, Bongaerts M, Delille F, Kolar-Znika L, Scolari VF, Hoffmann S, Banigan EJ, Mirny LA, Dahan M, Fachinetti D, Coulon A. Live-cell micromanipulation of a genomic locus reveals interphase chromatin mechanics. Science 2022; 377:489-495. [PMID: 35901134 DOI: 10.1126/science.abi9810] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Our understanding of the physical principles organizing the genome in the nucleus is limited by the lack of tools to directly exert and measure forces on interphase chromosomes in vivo and probe their material nature. Here, we introduce an approach to actively manipulate a genomic locus using controlled magnetic forces inside the nucleus of a living human cell. We observed viscoelastic displacements over micrometers within minutes in response to near-piconewton forces, which are consistent with a Rouse polymer model. Our results highlight the fluidity of chromatin, with a moderate contribution of the surrounding material, revealing minor roles for cross-links and topological effects and challenging the view that interphase chromatin is a gel-like material. Our technology opens avenues for future research in areas from chromosome mechanics to genome functions.
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Affiliation(s)
- Veer I P Keizer
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France.,Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Simon Grosse-Holz
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France.,Department of Physics and Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maxime Woringer
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Laura Zambon
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France.,Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Koceila Aizel
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Maud Bongaerts
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Fanny Delille
- ESPCI Paris, PSL Research University, Sorbonne Université, CNRS UMR8213, Laboratoire de Physique et d'Étude des Matériaux, 75005 Paris, France
| | - Lorena Kolar-Znika
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Vittore F Scolari
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Sebastian Hoffmann
- Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Edward J Banigan
- Department of Physics and Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Leonid A Mirny
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Department of Physics and Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maxime Dahan
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Daniele Fachinetti
- Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Antoine Coulon
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
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36
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Lin S, Rajan S, Lemberg S, Altawil M, Anderson K, Bryant R, Cappeta S, Chin B, Hamdan I, Hamer A, Hyzny R, Karp A, Lee D, Lim A, Nayak M, Palaniappan V, Park S, Satishkumar S, Seth A, Sri Dasari U, Toppari E, Vyas A, Walker J, Weston E, Zafar A, Zielke C, Mahabeleshwar GH, Tartakoff AM. Production of nascent ribosome precursors within the nucleolar microenvironment of Saccharomyces cerevisiae. Genetics 2022; 221:iyac070. [PMID: 35657327 PMCID: PMC9252279 DOI: 10.1093/genetics/iyac070] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
35S rRNA transcripts include a 5'-external transcribed spacer followed by rRNAs of the small and large ribosomal subunits. Their processing yields massive precursors that include dozens of assembly factor proteins. In Saccharomyces cerevisiae, nucleolar assembly factors form 2 coaxial layers/volumes around ribosomal DNA. Most of these factors are cyclically recruited from a latent state to an operative state, and are extensively conserved. The layers match, at least approximately, known subcompartments found in higher eukaryotic cells. ∼80% of assembly factors are essential. The number of copies of these assembly factors is comparable to the number of nascent transcripts. Moreover, they exhibit "isoelectric balance," with RNA-binding candidate "nucleator" assembly factors being notably basic. The physical properties of pre-small subunit and pre-large subunit assembly factors are similar, as are their 19 motif signatures detected by hierarchical clustering, unlike motif signatures of the 5'-external transcribed spacer rRNP. Additionally, many assembly factors lack shared motifs. Taken together with the progression of rRNP composition during subunit maturation, and the realization that the ribosomal DNA cable is initially bathed in a subunit-nonspecific assembly factor reservoir/microenvironment, we propose a "3-step subdomain assembly model": Step (1): predominantly basic assembly factors sequentially nucleate sites along nascent rRNA; Step (2): the resulting rRNPs recruit numerous less basic assembly factors along with notably basic ribosomal proteins; Step (3): rRNPs in nearby subdomains consolidate. Cleavages of rRNA then promote release of rRNPs to the nucleoplasm, likely facilitated by the persistence of assembly factors that were already associated with nucleolar precursors.
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Affiliation(s)
- Samantha Lin
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Suchita Rajan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sofia Lemberg
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mark Altawil
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Katherine Anderson
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ruth Bryant
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sebastian Cappeta
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Brandon Chin
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Isabella Hamdan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Annelise Hamer
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Rachel Hyzny
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Andrew Karp
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Daniel Lee
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Alexandria Lim
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Medha Nayak
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Vishnu Palaniappan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Soomin Park
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sarika Satishkumar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Anika Seth
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Uva Sri Dasari
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Emili Toppari
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ayush Vyas
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Julianne Walker
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Evan Weston
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Atif Zafar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Cecelia Zielke
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ganapati H Mahabeleshwar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Alan M Tartakoff
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
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37
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Abstract
It has long been proposed that nuclear RNAs might play an important role in organizing the structure of the nucleus. Initial experiments performed more than 30 years ago found that global disruption of RNA led to visible rearrangements of nuclear organization. Yet, this idea remained controversial for many years, in large part because it was unclear what specific RNAs might be involved, and which specific nuclear structures might be dependent on RNA. Over the past few years, the contributions of RNA to organizing nuclear structures have become clearer with the discovery that many nuclear bodies are enriched for specific noncoding RNAs (ncRNAs); in specific cases, ncRNAs have been shown to be essential for establishment and maintenance of these nuclear structures. More recently, many different ncRNAs have been shown to play critical roles in initiating the three-dimensional (3D) spatial organization of DNA, RNA, and protein molecules in the nucleus. These examples, combined with global imaging and genomic experiments, have begun to paint a picture of a broader role for RNA in nuclear organization and to uncover a unifying mechanism that may explain why RNA is a uniquely suited molecule for this role. In this review, we provide an overview of the history of RNA and nuclear structure and discuss key examples of RNA-mediated bodies, the global roles of ncRNAs in shaping nuclear structure, and emerging insights into mechanisms of RNA-mediated nuclear organization.
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Affiliation(s)
- Sofia A Quinodoz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
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38
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Characterization of RNA content in individual phase-separated coacervate microdroplets. Nat Commun 2022; 13:2626. [PMID: 35551426 PMCID: PMC9098875 DOI: 10.1038/s41467-022-30158-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 04/05/2022] [Indexed: 11/08/2022] Open
Abstract
Condensates formed by complex coacervation are hypothesized to have played a crucial part during the origin-of-life. In living cells, condensation organizes biomolecules into a wide range of membraneless compartments. Although RNA is a key component of biological condensates and the central component of the RNA world hypothesis, little is known about what determines RNA accumulation in condensates and to which extend single condensates differ in their RNA composition. To address this, we developed an approach to read the RNA content from single synthetic and protein-based condensates using high-throughput sequencing. We find that certain RNAs efficiently accumulate in condensates. These RNAs are strongly enriched in sequence motifs which show high sequence similarity to short interspersed elements (SINEs). We observe similar results for protein-derived condensates, demonstrating applicability across different in vitro reconstituted membraneless organelles. Thus, our results provide a new inroad to explore the RNA content of phase-separated droplets at single condensate resolution.
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39
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Böddeker TJ, Rosowski KA, Berchtold D, Emmanouilidis L, Han Y, Allain FHT, Style RW, Pelkmans L, Dufresne ER. Non-specific adhesive forces between filaments and membraneless organelles. NATURE PHYSICS 2022; 18:571-578. [PMID: 35582428 PMCID: PMC9106579 DOI: 10.1038/s41567-022-01537-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 02/04/2022] [Indexed: 05/07/2023]
Abstract
Many membraneless organelles are liquid-like domains that form inside the active, viscoelastic environment of living cells through phase separation. To investigate the potential coupling of phase separation with the cytoskeleton, we quantify the structural correlations of membraneless organelles (stress granules) and cytoskeletal filaments (microtubules) in a human-derived epithelial cell line. We find that microtubule networks are substantially denser in the vicinity of stress granules. When microtubules are depolymerized, the sub-units localize near the surface of the stress granules. We interpret these data using a thermodynamic model of partitioning of particles to the surface and bulk of the droplets. In this framework, our data are consistent with a weak (≲k B T) affinity of the microtubule sub-units for stress granule interfaces. As microtubules polymerize, their interfacial affinity increases, providing sufficient adhesion to deform droplets and/or the network. Our work suggests that proteins and other objects in the cell have a non-specific affinity for droplet interfaces that increases with the contact area and becomes most apparent when they have no preference for the interior of a droplet over the rest of the cytoplasm. We validate this basic physical phenomenon in vitro through the interaction of a simple protein-RNA condensate with microtubules.
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Affiliation(s)
| | | | - Doris Berchtold
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | | | - Yaning Han
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | | | | | - Lucas Pelkmans
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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40
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Garaizar A, Espinosa JR, Joseph JA, Collepardo-Guevara R. Kinetic interplay between droplet maturation and coalescence modulates shape of aged protein condensates. Sci Rep 2022; 12:4390. [PMID: 35293386 PMCID: PMC8924231 DOI: 10.1038/s41598-022-08130-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 02/07/2022] [Indexed: 12/29/2022] Open
Abstract
Biomolecular condensates formed by the process of liquid-liquid phase separation (LLPS) play diverse roles inside cells, from spatiotemporal compartmentalisation to speeding up chemical reactions. Upon maturation, the liquid-like properties of condensates, which underpin their functions, are gradually lost, eventually giving rise to solid-like states with potential pathological implications. Enhancement of inter-protein interactions is one of the main mechanisms suggested to trigger the formation of solid-like condensates. To gain a molecular-level understanding of how the accumulation of stronger interactions among proteins inside condensates affect the kinetic and thermodynamic properties of biomolecular condensates, and their shapes over time, we develop a tailored coarse-grained model of proteins that transition from establishing weak to stronger inter-protein interactions inside condensates. Our simulations reveal that the fast accumulation of strongly binding proteins during the nucleation and growth stages of condensate formation results in aspherical solid-like condensates. In contrast, when strong inter-protein interactions appear only after the equilibrium condensate has been formed, or when they accumulate slowly over time with respect to the time needed for droplets to fuse and grow, spherical solid-like droplets emerge. By conducting atomistic potential-of-mean-force simulations of NUP-98 peptides-prone to forming inter-protein [Formula: see text]-sheets-we observe that formation of inter-peptide [Formula: see text]-sheets increases the strength of the interactions consistently with the loss of liquid-like condensate properties we observe at the coarse-grained level. Overall, our work aids in elucidating fundamental molecular, kinetic, and thermodynamic mechanisms linking the rate of change in protein interaction strength to condensate shape and maturation during ageing.
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Affiliation(s)
- Adiran Garaizar
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Jerelle A Joseph
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Department of Genetics, University of Cambridge, Downing Site, Cambridge, CB2 3EH, UK
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
- Department of Genetics, University of Cambridge, Downing Site, Cambridge, CB2 3EH, UK.
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41
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Abstract
In eukaryotic cells, protein and RNA factors involved in genome activities like transcription, RNA processing, DNA replication, and repair accumulate in self-organizing membraneless chromatin subcompartments. These structures contribute to efficiently conduct chromatin-mediated reactions and to establish specific cellular programs. However, the underlying mechanisms for their formation are only partly understood. Recent studies invoke liquid-liquid phase separation (LLPS) of proteins and RNAs in the establishment of chromatin activity patterns. At the same time, the folding of chromatin in the nucleus can drive genome partitioning into spatially distinct domains. Here, the interplay between chromatin organization, chromatin binding, and LLPS is discussed by comparing and contrasting three prototypical chromatin subcompartments: the nucleolus, clusters of active RNA polymerase II, and pericentric heterochromatin domains. It is discussed how the different ways of chromatin compartmentalization are linked to transcription regulation, the targeting of soluble factors to certain parts of the genome, and to disease-causing genetic aberrations.
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Affiliation(s)
- Karsten Rippe
- Division of Chromatin Networks, German Cancer Research Center (DKFZ) and Bioquant, 69120 Heidelberg, Germany
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42
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Schlüßler R, Kim K, Nötzel M, Taubenberger A, Abuhattum S, Beck T, Müller P, Maharana S, Cojoc G, Girardo S, Hermann A, Alberti S, Guck J. Correlative all-optical quantification of mass density and mechanics of subcellular compartments with fluorescence specificity. eLife 2022; 11:e68490. [PMID: 35001870 PMCID: PMC8816383 DOI: 10.7554/elife.68490] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 01/08/2022] [Indexed: 01/06/2023] Open
Abstract
Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples - so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical diffraction tomography and epifluorescence imaging for explicitly measuring the Brillouin shift, RI, and absolute density with specificity to fluorescently labeled structures. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the nucleoplasm of wild-type HeLa cells, we find that it has lower density but higher longitudinal modulus than the cytoplasm. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample - a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.
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Affiliation(s)
- Raimund Schlüßler
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Kyoohyun Kim
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Martin Nötzel
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Anna Taubenberger
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Shada Abuhattum
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Timon Beck
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Paul Müller
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Shovamaye Maharana
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Department of Microbiology and Cell Biology, Indian Institute of ScienceBengaluruIndia
| | - Gheorghe Cojoc
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
| | - Salvatore Girardo
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
| | - Andreas Hermann
- Translational Neurodegeneration Section "Albrecht Kossel", University Rostock, and German Center for Neurodegenerative Diseases (DZNE)Rostock/GreifswaldGermany
| | - Simon Alberti
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Physics of Life, Technische Universität DresdenDresdenGermany
| | - Jochen Guck
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische UniversitätDresdenGermany
- Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und MedizinErlangenGermany
- Physics of Life, Technische Universität DresdenDresdenGermany
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43
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Kasselimi E, Pefani DE, Taraviras S, Lygerou Z. Ribosomal DNA and the nucleolus at the heart of aging. Trends Biochem Sci 2022; 47:328-341. [DOI: 10.1016/j.tibs.2021.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/15/2022]
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44
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Natesan R, Gowrishankar K, Kuttippurathu L, Kumar PBS, Rao M. Active Remodeling of Chromatin and Implications for In Vivo Folding. J Phys Chem B 2021; 126:100-109. [DOI: 10.1021/acs.jpcb.1c08655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ramakrishnan Natesan
- Department of Cancer Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | | | - Lakshmi Kuttippurathu
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Daniel Baugh Institute for Functional Genomics and Computational Biology, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, United States
| | - P. B. Sunil Kumar
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Department of Physics, Indian Institute of Technology Palakkad, Palakkad 668557, Kerala, India
| | - Madan Rao
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences (TIFR), Bengaluru 560065, India
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45
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Caragine CM, Kanellakopoulos N, Zidovska A. Mechanical stress affects dynamics and rheology of the human genome. SOFT MATTER 2021; 18:107-116. [PMID: 34874386 DOI: 10.1039/d1sm00983d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Material properties of the genome are critical for proper cellular function - they directly affect timescales and length scales of DNA transactions such as transcription, replication and DNA repair, which in turn impact all cellular processes via the central dogma of molecular biology. Hence, elucidating the genome's rheology in vivo may help reveal physical principles underlying the genome's organization and function. Here, we present a novel noninvasive approach to study the genome's rheology and its response to mechanical stress in form of nuclear injection in live human cells. Specifically, we use Displacement Correlation Spectroscopy to map nucleus-wide genomic motions pre/post injection, during which we deposit rheological probes inside the cell nucleus. While the genomic motions inform on the bulk rheology of the genome pre/post injection, the probe's motion informs on the local rheology of its surroundings. Our results reveal that mechanical stress of injection leads to local as well as nucleus-wide changes in the genome's compaction, dynamics and rheology. We find that the genome pre-injection exhibits subdiffusive motions, which are coherent over several micrometers. In contrast, genomic motions post-injection become faster and uncorrelated, moreover, the genome becomes less compact and more viscous across the entire nucleus. In addition, we use the injected particles as rheological probes and find the genome to condense locally around them, mounting a local elastic response. Taken together, our results show that mechanical stress alters both dynamics and material properties of the genome. These changes are consistent with those observed upon DNA damage, suggesting that the genome experiences similar effects during the injection process.
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Affiliation(s)
- Christina M Caragine
- Center for Soft Matter Research, Department of Physics, New York University, New York, NY 10003, USA.
| | - Nikitas Kanellakopoulos
- Center for Soft Matter Research, Department of Physics, New York University, New York, NY 10003, USA.
| | - Alexandra Zidovska
- Center for Soft Matter Research, Department of Physics, New York University, New York, NY 10003, USA.
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Abstract
Nuclear bodies are membraneless condensates that may form via liquid-liquid phase separation. The viscoelastic chromatin network could impact their stability and may hold the key for understanding experimental observations that defy predictions of classical theories. However, quantitative studies on the role of the chromatin network in phase separation have remained challenging. Using a diploid human genome model parameterized with chromosome conformation capture (Hi-C) data, we study the thermodynamics and kinetics of nucleoli formation. Dynamical simulations predict the formation of multiple droplets for nucleolar particles that experience specific interactions with nucleolus-associated domains (NADs). Coarsening dynamics, surface tension, and coalescence kinetics of the simulated droplets are all in quantitative agreement with experimental measurements for nucleoli. Free energy calculations further support that a two-droplet state, often observed for nucleoli in somatic cells, is metastable and separated from the single-droplet state with an entropic barrier. Our study suggests that nucleoli-chromatin interactions facilitate droplets' nucleation but hinder their coarsening due to the coupled motion between droplets and the chromatin network: as droplets coalesce, the chromatin network becomes increasingly constrained. Therefore, the chromatin network supports a nucleation and arrest mechanism to stabilize the multi-droplet state for nucleoli and possibly for other nuclear bodies.
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Zhu Y, Cheng C, Chen L, Zhang L, Pan H, Hou L, Sun Z, Zhang L, Fu X, Chan KY, Zhang J. Cell cycle heterogeneity directs spontaneous 2C state entry and exit in mouse embryonic stem cells. Stem Cell Reports 2021; 16:2659-2673. [PMID: 34624246 PMCID: PMC8580870 DOI: 10.1016/j.stemcr.2021.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/01/2022] Open
Abstract
Mouse embryonic stem cells (ESCs) show cell-to-cell heterogeneity. A small number of two-cell-like cells (2CLCs) marked by endogenous retrovirus activation emerge spontaneously. The 2CLCs are unstable and they are prone to transiting back to the pluripotent state without extrinsic stimulus. To understand how this bidirectional transition takes place, we performed single-cell RNA sequencing on isolated 2CLCs that underwent 2C-like state exit and re-entry, and revealed a step-by-step transitional process between 2C-like and pluripotent states. Mechanistically, we found that cell cycle played an important role in mediating these transitions by regulating assembly of the nucleolus and peri-nucleolar heterochromatin to influence 2C gene Dux expression. Collectively, our findings provide a roadmap of the 2C-like state entry and exit in ESCs and also a causal role of the cell cycle in promoting these transitions. The entry to and exit from the 2C-like state showed a step-by-step roadmap Cell cycle participates in mediating dynamic transitions between ESCs and 2CLCs G1/S phase arrest facilitates the Dux locus escape from heterochromatin Nucleolus-heterochromatin remodeling is involved in 2C activation
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Affiliation(s)
- Yuqing Zhu
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China; Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Haining, Zhejiang, China
| | - Chen Cheng
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Lang Chen
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Li Zhang
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Hongru Pan
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Linxiao Hou
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Zhen Sun
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Ling Zhang
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China; Zhejiang Laboratory for Systems and Precision Medicine, Zhejiang University Medical Center, Hangzhou, Zhejiang, China
| | - Xudong Fu
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China; Zhejiang Laboratory for Systems and Precision Medicine, Zhejiang University Medical Center, Hangzhou, Zhejiang, China; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kuan Yoow Chan
- Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Haining, Zhejiang, China
| | - Jin Zhang
- Center for Stem Cell and Regenerative Medicine, Department of Basic Medical Sciences, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Hangzhou, Zhejiang, China; Zhejiang Laboratory for Systems and Precision Medicine, Zhejiang University Medical Center, Hangzhou, Zhejiang, China; Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, China; Center of Gene/Cell Engineering and Genome Medicine, Hangzhou, Zhejiang, China.
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Wang M, Zinga K, Zidovska A, Grosberg AY. Tethered tracer in a mixture of hot and cold Brownian particles: can activity pacify fluctuations? SOFT MATTER 2021; 17:9528-9539. [PMID: 34617946 DOI: 10.1039/d1sm01163d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We study how an interacting mixture of components with differing levels of activity can affect the fluctuations of an embedded object such as a tracer. In particular, we consider a simple model of a tracer that is harmonically bound within a mixture of hot and cold Brownian particles, which, like a mixture of active and passive particles, can phase separate. By measuring the fluctuations of the tracer, we find that this collective behavior gives rise to an effective temperature for the tracer. Additionally, we find that there is an increased tendency for cold particles to accumulate on the surface of the tracer due to the hot particles, potentially dampening its fluctuations and decreasing its effective temperature. These results suggest that the phase separation of a mixture of hot/cold or active/passive particles may have strong effects on the fluctuations of an embedded object. We discuss potential implications of these results for experiments on fluctuations of nuclear envelope affected by the activity in the chromatin.
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Affiliation(s)
- Michael Wang
- Department of Physics and Center for Soft Matter Research, New York University, 726 Broadway, New York, NY 10003, USA.
| | - Ketsia Zinga
- Department of Physics and Center for Soft Matter Research, New York University, 726 Broadway, New York, NY 10003, USA.
| | - Alexandra Zidovska
- Department of Physics and Center for Soft Matter Research, New York University, 726 Broadway, New York, NY 10003, USA.
| | - Alexander Y Grosberg
- Department of Physics and Center for Soft Matter Research, New York University, 726 Broadway, New York, NY 10003, USA.
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49
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Dissecting the complexity of biomolecular condensates. Biochem Soc Trans 2021; 48:2591-2602. [PMID: 33300985 DOI: 10.1042/bst20200351] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 11/17/2022]
Abstract
Biomolecular condensates comprise a diverse and ubiquitous class of membraneless organelles. Condensate assembly is often described by liquid-liquid phase separation. While this process explains many key features, it cannot account for the compositional or architectural complexity that condensates display in cells. Recent work has begun to dissect the rich network of intermolecular interactions that give rise to biomolecular condensates. Here, we review the latest results from theory, simulations and experiments, and discuss what they reveal about the structure-function relationship of condensates.
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Erenpreisa J, Krigerts J, Salmina K, Gerashchenko BI, Freivalds T, Kurg R, Winter R, Krufczik M, Zayakin P, Hausmann M, Giuliani A. Heterochromatin Networks: Topology, Dynamics, and Function (a Working Hypothesis). Cells 2021; 10:1582. [PMID: 34201566 PMCID: PMC8304199 DOI: 10.3390/cells10071582] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/21/2022] Open
Abstract
Open systems can only exist by self-organization as pulsing structures exchanging matter and energy with the outer world. This review is an attempt to reveal the organizational principles of the heterochromatin supra-intra-chromosomal network in terms of nonlinear thermodynamics. The accessibility of the linear information of the genetic code is regulated by constitutive heterochromatin (CHR) creating the positional information in a system of coordinates. These features include scale-free splitting-fusing of CHR with the boundary constraints of the nucleolus and nuclear envelope. The analysis of both the literature and our own data suggests a radial-concentric network as the main structural organization principle of CHR regulating transcriptional pulsing. The dynamic CHR network is likely created together with nucleolus-associated chromatin domains, while the alveoli of this network, including springy splicing speckles, are the pulsing transcription hubs. CHR contributes to this regulation due to the silencing position variegation effect, stickiness, and flexible rigidity determined by the positioning of nucleosomes. The whole system acts in concert with the elastic nuclear actomyosin network which also emerges by self-organization during the transcriptional pulsing process. We hypothesize that the the transcriptional pulsing, in turn, adjusts its frequency/amplitudes specified by topologically associating domains to the replication timing code that determines epigenetic differentiation memory.
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Affiliation(s)
- Jekaterina Erenpreisa
- Latvian Biomedicine Research and Study Centre, LV-1067 Riga, Latvia; (J.K.); (K.S.); (P.Z.)
| | - Jekabs Krigerts
- Latvian Biomedicine Research and Study Centre, LV-1067 Riga, Latvia; (J.K.); (K.S.); (P.Z.)
| | - Kristine Salmina
- Latvian Biomedicine Research and Study Centre, LV-1067 Riga, Latvia; (J.K.); (K.S.); (P.Z.)
| | - Bogdan I. Gerashchenko
- R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, National Academy of Sciences of Ukraine, 03022 Kyiv, Ukraine;
| | - Talivaldis Freivalds
- Institute of Cardiology and Regenerative Medicine, University of Latvia, LV-1004 Riga, Latvia;
| | - Reet Kurg
- Institute of Technology, University of Tartu, 50411 Tartu, Estonia;
| | - Ruth Winter
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (R.W.); (M.K.); (M.H.)
| | - Matthias Krufczik
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (R.W.); (M.K.); (M.H.)
| | - Pawel Zayakin
- Latvian Biomedicine Research and Study Centre, LV-1067 Riga, Latvia; (J.K.); (K.S.); (P.Z.)
| | - Michael Hausmann
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (R.W.); (M.K.); (M.H.)
| | - Alessandro Giuliani
- Istituto Superiore di Sanita Environment and Health Department, 00161 Roma, Italy
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