Single-nucleosome imaging unveils that condensins and nucleosome–nucleosome interactions differentially constrain chromatin to organize mitotic chromosomes

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Aug. 21, 2024

For accurate mitotic cell division, replicated chromatin must be assembled into chromosomes and faithfully segregated daughter cells. While protein factors like condensin play key roles in this process, it is unclear how chromosome assembly proceeds as molecular events of nucleosomes living cells condensins act on to organize chromosomes. To approach these questions, we investigate nucleosome behavior during mitosis human using single-nucleosome tracking, combined with rapid-protein depletion technology computational modeling. Our results show that local motion becomes increasingly constrained assembly, which functionally distinct from condensed apoptotic chromatin. Condensins crosslinkers, locally constraining Additionally, nucleosome-nucleosome interactions via histone tails constrain compact whole findings elucidate the physical nature process mitosis.

Language: Английский

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Replication-dependent histone labeling dissects the physical properties of euchromatin/heterochromatin in living human cells

Science Advances, Journal Year: 2025, Volume and Issue: 11(13)

Published: March 28, 2025

A string of nucleosomes, where genomic DNA is wrapped around histones, organized in the cell as chromatin, ranging from euchromatin to heterochromatin, with distinct genome functions. Understanding physical differences between and heterochromatin crucial, yet specific labeling methods living cells remain limited. Here, we have developed replication-dependent histone (Repli-Histo) mark nucleosomes based on replication timing. Using this approach, investigated local nucleosome motion four known chromatin classes, human mouse cells. The more euchromatic (earlier-replicated) heterochromatic (later-replicated) regions exhibit greater lesser motions, respectively. Notably, profile each class persists throughout interphase. Genome essentially replicated although timing perturbed. Our findings, combined computational modeling, suggest that earlier-replicated accessibility, can be a major determinant genome-wide

Language: Английский

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Chromatin domains in the cell: Phase separation and condensation

Current Opinion in Structural Biology, Journal Year: 2025, Volume and Issue: 91, P. 103006 - 103006

Published: Feb. 20, 2025

Language: Английский

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Lipids Are Involved in Heterochromatin Condensation: A Quantitative Raman and Brillouin Microscopy Study

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown

Published: March 2, 2025

Abstract Chromatin, a fundamental component of eukaryotic genomes, is categorized into euchromatin and heterochromatin, which play distinct roles in gene regulation. Although these two chromatin states are distinguished by their degree condensation, quantitatively measuring the as well physical properties living cells, remains challenging. In this study, label-free situ quantitative imaging was performed using Raman-Brillouin microscope to visualize spatial distribution molecular concentration viscoelasticity within nuclear environment cell. A image each intracellular biomolecule obtained combining Raman with multivariate curve resolution analysis, water band an internal standard. Simultaneous enables visualization Using approach, we found that, addition DNA, heterochromatin enriched lipids that critical role formation, determining its mechanical properties. These findings provide new insights mechanism formation chemical properties, leading comprehensive understanding regulation organization.

Language: Английский

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Mechanical Forces, Nucleus, Chromosomes, and Chromatin

Biomolecules, Journal Year: 2025, Volume and Issue: 15(3), P. 354 - 354

Published: March 1, 2025

Individual cells and within the tissues organs constantly face mechanical challenges, such as tension, compression, strain, shear stress, rigidity of cellular extracellular surroundings. Besides external forces, their components are also subjected to intracellular pulling, pushing, stretching, created by sophisticated force-generation machinery cytoskeleton molecular motors. All these stressors switch on mechanotransduction pathways, allowing respond adapt. Mechanical force-induced changes at cell membrane transmitted nucleus its nucleoskeleton, affecting nucleocytoplasmic transport, chromatin conformation, transcriptional activity, replication, genome, which, in turn, orchestrate behavior. The memory mechanoresponses is stored epigenetic structure modifications. state response acellular environment determines identity, fate, immune invading pathogens. Here, we give a short overview latest developments understanding processes, emphasizing effects nuclei, chromosomes, chromatin.

Language: Английский

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The shifting paradigm of chromatin structure: from the 30-nm chromatin fiber to liquid-like organization

Proceedings of the Japan Academy Series B, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

The organization and dynamics of chromatin are critical for genome functions such as transcription DNA replication/repair. Historically, was assumed to fold into the 30-nm fiber progressively arrange larger helical structures, described in textbook model. However, over past 15 years, extensive evidence including our studies has dramatically transformed view from a static, regular structure one that is more variable dynamic. In higher eukaryotic cells, forms condensed yet liquid-like domains, which appear be basic unit structure, replacing fiber. These domains maintain proper accessibility, ensuring regulation reaction processes. During mitosis, these assemble form gel-like mitotic chromosomes, further constrained by condensins other factors. Based on available evidence, I discuss physical properties live emphasizing its viscoelastic nature-balancing local fluidity with global stability support functions.

Language: Английский

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Toward decoding the mechanisms that shape sub-megabase-scale genome organization

Current Opinion in Structural Biology, Journal Year: 2025, Volume and Issue: 92, P. 103062 - 103062

Published: May 8, 2025

Language: Английский

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Replication-dependent histone (Repli-Histo) labeling dissects the physical properties of euchromatin/heterochromatin in living human cells.

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 21, 2024

Abstract A string of nucleosomes, where genomic DNA is wrapped around histones, organized in the cell as chromatin. Chromatin varies greatly, from euchromatin to heterochromatin, its genome functions. It important understand how heterochromatin physically different euchromatin. However, their specific labeling methods living cells are limited. To address this, we have developed replication-dependent histone (Repli-Histo labeling) label nucleosomes and based on replication timing. We investigated local nucleosome motion four chromatin classes human mouse cells. found that more euchromatic regions (earlier replicated regions) show greater motion. Notably, profile each class persists throughout interphase. Genome essentially with motions, even though timing program perturbed. Our findings, combined computational modeling, suggest earlier accessibility can be a major determinant genome-wide

Language: Английский

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Live-cell imaging under centrifugation characterized the cellular force for nuclear centration in the Caenorhabditis elegans embryo

Proceedings of the National Academy of Sciences, Journal Year: 2024, Volume and Issue: 121(43)

Published: Oct. 16, 2024

Organelles in cells are appropriately positioned, despite crowding the cytoplasm. However, our understanding of force required to move large organelles, such as nucleus, inside cytoplasm is limited, part owing a lack accurate methods for measurement. We devised method apply forces nucleus living Caenorhabditis elegans embryos measure generated cell. used centrifuge polarizing microscope centrifugal and orientation-independent differential interference contrast microscopy characterize mass density The cellular moving toward cell center increased linearly at ~12 pN/μm depending on distance from center. frictional coefficient was ~980 pN s/μm. measured values were smaller than previously reported estimates sea urchin embryos. consistent with centrosome-organelle mutual pulling model nuclear centration. reduced when microtubules shorter or detached nuclei mutant embryos, demonstrating contribution astral microtubules. Finally, higher theoretical estimate, indicating uncharacterized properties

Language: Английский

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How condensed are mitotic chromosomes?

The Journal of Cell Biology, Journal Year: 2024, Volume and Issue: 223(11)

Published: Oct. 14, 2024

Chromosomes undergo dramatic compaction during mitosis, but accurately measuring their volume has been challenging. Employing serial block face scanning electron microscopy, Cisneros-Soberanis et al. (https://doi.org/10.1083/jcb.202403165) report that mitotic chromosomes compact to a nucleosome concentration of ∼760 µM.

Language: Английский

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