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Presman DM, Benítez B, Lafuente AL, Vázquez Lareu A. Chromatin structure and dynamics: one nucleosome at a time. Histochem Cell Biol 2024; 162:79-90. [PMID: 38607419 DOI: 10.1007/s00418-024-02281-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2024] [Indexed: 04/13/2024]
Abstract
Eukaryotic genomes store information on many levels, including their linear DNA sequence, the posttranslational modifications of its constituents (epigenetic modifications), and its three-dimensional folding. Understanding how this information is stored and read requires multidisciplinary collaborations from many branches of science beyond biology, including physics, chemistry, and computer science. Concurrent recent developments in all these areas have enabled researchers to image the genome with unprecedented spatial and temporal resolution. In this review, we focus on what single-molecule imaging and tracking of individual proteins in live cells have taught us about chromatin structure and dynamics. Starting with the basics of single-molecule tracking (SMT), we describe some advantages over in situ imaging techniques and its current limitations. Next, we focus on single-nucleosome studies and what they have added to our current understanding of the relationship between chromatin dynamics and transcription. In celebration of Robert Feulgen's ground-breaking discovery that allowed us to start seeing the genome, we discuss current models of chromatin structure and future challenges ahead.
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Affiliation(s)
- Diego M Presman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina.
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina.
| | - Belén Benítez
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Agustina L Lafuente
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Alejo Vázquez Lareu
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
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Mierke CT. Extracellular Matrix Cues Regulate Mechanosensing and Mechanotransduction of Cancer Cells. Cells 2024; 13:96. [PMID: 38201302 PMCID: PMC10777970 DOI: 10.3390/cells13010096] [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: 11/12/2023] [Revised: 12/29/2023] [Accepted: 01/01/2024] [Indexed: 01/12/2024] Open
Abstract
Extracellular biophysical properties have particular implications for a wide spectrum of cellular behaviors and functions, including growth, motility, differentiation, apoptosis, gene expression, cell-matrix and cell-cell adhesion, and signal transduction including mechanotransduction. Cells not only react to unambiguously mechanical cues from the extracellular matrix (ECM), but can occasionally manipulate the mechanical features of the matrix in parallel with biological characteristics, thus interfering with downstream matrix-based cues in both physiological and pathological processes. Bidirectional interactions between cells and (bio)materials in vitro can alter cell phenotype and mechanotransduction, as well as ECM structure, intentionally or unintentionally. Interactions between cell and matrix mechanics in vivo are of particular importance in a variety of diseases, including primarily cancer. Stiffness values between normal and cancerous tissue can range between 500 Pa (soft) and 48 kPa (stiff), respectively. Even the shear flow can increase from 0.1-1 dyn/cm2 (normal tissue) to 1-10 dyn/cm2 (cancerous tissue). There are currently many new areas of activity in tumor research on various biological length scales, which are highlighted in this review. Moreover, the complexity of interactions between ECM and cancer cells is reduced to common features of different tumors and the characteristics are highlighted to identify the main pathways of interaction. This all contributes to the standardization of mechanotransduction models and approaches, which, ultimately, increases the understanding of the complex interaction. Finally, both the in vitro and in vivo effects of this mechanics-biology pairing have key insights and implications for clinical practice in tumor treatment and, consequently, clinical translation.
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Affiliation(s)
- Claudia Tanja Mierke
- Biological Physics Division, Peter Debye Institute of Soft Matter Physics, Faculty of Physics and Earth Science, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
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Weinmann R, Frank L, Rippe K. Approaches to characterize chromatin subcompartment organization in the cell nucleus. Curr Opin Struct Biol 2023; 83:102695. [PMID: 37722292 DOI: 10.1016/j.sbi.2023.102695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/05/2023] [Accepted: 08/07/2023] [Indexed: 09/20/2023]
Abstract
The mechanism of self-organization of chromatin subcompartments on the 0.1-1 μm scale and their impact on genome-associated activities has long been a key aspect of research on nuclear organization. Understanding the underlying structure-function relationship, however, remains challenging due to the complex hierarchical structure of chromatin and the polymorphic organization of subcompartments that assemble around it. Towards this goal, approaches to measure local properties and compositional dynamics of chromatin in its endogenous cellular environment are instrumental. Here, we discuss recent advancements in studying these features and their functional implications in protein and RNA enrichment and genome accessibility.
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Affiliation(s)
- Robin Weinmann
- German Cancer Research Center (DKFZ) Heidelberg, Division of Chromatin Networks, Germany; Center for Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), Heidelberg University, Germany; Faculty of Biosciences, Heidelberg University, Germany
| | - Lukas Frank
- German Cancer Research Center (DKFZ) Heidelberg, Division of Chromatin Networks, Germany; Center for Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), Heidelberg University, Germany
| | - Karsten Rippe
- German Cancer Research Center (DKFZ) Heidelberg, Division of Chromatin Networks, Germany; Center for Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), Heidelberg University, Germany.
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Melters DP, Neuman KC, Bentahar RS, Rakshit T, Dalal Y. Single molecule analysis of CENP-A chromatin by high-speed atomic force microscopy. eLife 2023; 12:e86709. [PMID: 37728600 PMCID: PMC10511241 DOI: 10.7554/elife.86709] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 09/01/2023] [Indexed: 09/21/2023] Open
Abstract
Chromatin accessibility is modulated in a variety of ways to create open and closed chromatin states, both of which are critical for eukaryotic gene regulation. At the single molecule level, how accessibility is regulated of the chromatin fiber composed of canonical or variant nucleosomes is a fundamental question in the field. Here, we developed a single-molecule tracking method where we could analyze thousands of canonical H3 and centromeric variant nucleosomes imaged by high-speed atomic force microscopy. This approach allowed us to investigate how changes in nucleosome dynamics in vitro inform us about transcriptional potential in vivo. By high-speed atomic force microscopy, we tracked chromatin dynamics in real time and determined the mean square displacement and diffusion constant for the variant centromeric CENP-A nucleosome. Furthermore, we found that an essential kinetochore protein CENP-C reduces the diffusion constant and mobility of centromeric nucleosomes along the chromatin fiber. We subsequently interrogated how CENP-C modulates CENP-A chromatin dynamics in vivo. Overexpressing CENP-C resulted in reduced centromeric transcription and impaired loading of new CENP-A molecules. From these data, we speculate that factors altering nucleosome mobility in vitro, also correspondingly alter transcription in vivo. Subsequently, we propose a model in which variant nucleosomes encode their own diffusion kinetics and mobility, and where binding partners can suppress or enhance nucleosome mobility.
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Affiliation(s)
- Daniël P Melters
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
| | - Keir C Neuman
- National Heart, Lung, and Blood Institute, Laboratory of Single Molecule BiophysicsBethesdaUnited States
| | - Reda S Bentahar
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
| | - Tatini Rakshit
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
- Department of Chemistry, Shiv Nadar UniversityDadriIndia
| | - Yamini Dalal
- National Cancer Institute, Center for Cancer Research, Laboratory Receptor Biology and Gene ExpressionBethesdaUnited States
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Liang Y, Willey S, Chung YC, Lo YM, Miao S, Rundell S, Tu LC, Bong D. Intracellular RNA and DNA tracking by uridine-rich internal loop tagging with fluorogenic bPNA. Nat Commun 2023; 14:2987. [PMID: 37225690 DOI: 10.1038/s41467-023-38579-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 05/05/2023] [Indexed: 05/26/2023] Open
Abstract
The most widely used method for intracellular RNA fluorescence labeling is MS2 labeling, which generally relies on the use of multiple protein labels targeted to multiple RNA (MS2) hairpin structures installed on the RNA of interest (ROI). While effective and conveniently applied in cell biology labs, the protein labels add significant mass to the bound RNA, which potentially impacts steric accessibility and native RNA biology. We have previously demonstrated that internal, genetically encoded, uridine-rich internal loops (URILs) comprised of four contiguous UU pairs (8 nt) in RNA may be targeted with minimal structural perturbation by triplex hybridization with 1 kD bifacial peptide nucleic acids (bPNAs). A URIL-targeting strategy for RNA and DNA tracking would avoid the use of cumbersome protein fusion labels and minimize structural alterations to the RNA of interest. Here we show that URIL-targeting fluorogenic bPNA probes in cell media can penetrate cell membranes and effectively label RNAs and RNPs in fixed and live cells. This method, which we call fluorogenic U-rich internal loop (FLURIL) tagging, was internally validated through the use of RNAs bearing both URIL and MS2 labeling sites. Notably, a direct comparison of CRISPR-dCas labeled genomic loci in live U2OS cells revealed that FLURIL-tagged gRNA yielded loci with signal to background up to 7X greater than loci targeted by guide RNA modified with an array of eight MS2 hairpins. Together, these data show that FLURIL tagging provides a versatile scope of intracellular RNA and DNA tracking while maintaining a light molecular footprint and compatibility with existing methods.
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Affiliation(s)
- Yufeng Liang
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Sydney Willey
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA
| | - Yu-Chieh Chung
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
| | - Yi-Meng Lo
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Shiqin Miao
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Sarah Rundell
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Li-Chun Tu
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA.
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.
| | - Dennis Bong
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH, USA.
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
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Thuma J, Chung YC, Tu LC. Advances and challenges in CRISPR-based real-time imaging of dynamic genome organization. Front Mol Biosci 2023; 10:1173545. [PMID: 37065447 PMCID: PMC10102487 DOI: 10.3389/fmolb.2023.1173545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/23/2023] [Indexed: 04/03/2023] Open
Abstract
Nuclear chromosome compaction is non-random and dynamic. The spatial distance among genomic elements instantly modulates transcription. Visualization of the genome organization in the cell nucleus is essential to understand nuclear function. In addition to cell type-dependent organization, high-resolution 3D imaging shows heterogeneous compaction of chromatin organization among the same cell type. Questions remain to be answered if these structural variations were the snapshots of dynamic organization at different time points and if they are functionally different. Live-cell imaging has provided unique insights into dynamic genome organization at short (milliseconds) and long (hours) time scales. The recent development of CRISPR-based imaging opened windows for studying dynamic chromatin organization in single cells in real time. Here we highlight these CRISPR-based imaging techniques and discuss their advances and challenges as a powerful live-cell imaging method that poses high potential to generate paradigm-shifting discoveries and reveal functional implications of dynamic chromatin organization.
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Affiliation(s)
- Jenna Thuma
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, United States
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH, United States
| | - Yu-Chieh Chung
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, United States
| | - Li-Chun Tu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, United States
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH, United States
- Center for RNA Biology, The Ohio State University, Columbus, OH, United States
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH, United States
- *Correspondence: Li-Chun Tu,
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