1
|
Yuan T, Yan H, Bailey MLP, Williams JF, Surovtsev I, King MC, Mochrie SGJ. Effect of loops on the mean-square displacement of Rouse-model chromatin. Phys Rev E 2024; 109:044502. [PMID: 38755928 DOI: 10.1103/physreve.109.044502] [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: 04/24/2023] [Accepted: 02/16/2024] [Indexed: 05/18/2024]
Abstract
Chromatin polymer dynamics are commonly described using the classical Rouse model. The subsequent discovery, however, of intermediate-scale chromatin organization known as topologically associating domains (TADs) in experimental Hi-C contact maps for chromosomes across the tree of life, together with the success of loop extrusion factor (LEF) model in explaining TAD formation, motivates efforts to understand the effect of loops and loop extrusion on chromatin dynamics. This paper seeks to fulfill this need by combining LEF-model simulations with extended Rouse-model polymer simulations to investigate the dynamics of chromatin with loops and dynamic loop extrusion. We show that loops significantly suppress the averaged mean-square displacement (MSD) of a gene locus, consistent with recent experiments that track fluorescently labeled chromatin loci. We also find that loops reduce the MSD's stretching exponent from the classical Rouse-model value of 1/2 to a loop-density-dependent value in the 0.45-0.40 range. Remarkably, stretching exponent values in this range have also been observed in recent experiments [Weber et al., Phys. Rev. Lett. 104, 238102 (2010)0031-900710.1103/PhysRevLett.104.238102; Bailey et al., Mol. Biol. Cell 34, ar78 (2023)1059-152410.1091/mbc.E23-04-0119]. We also show that the dynamics of loop extrusion itself negligibly affects chromatin mobility. By studying static "rosette" loop configurations, we also demonstrate that chromatin MSDs and stretching exponents depend on the location of the locus in question relative to the position of the loops and on the local friction environment.
Collapse
Affiliation(s)
- Tianyu Yuan
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Hao Yan
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Mary Lou P Bailey
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Jessica F Williams
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Ivan Surovtsev
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Megan C King
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520, USA
- Department of Molecular, Cell and Developmental Biology, Yale University, New Haven, Connecticut 06511, USA
| | - Simon G J Mochrie
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| |
Collapse
|
2
|
Carollo PS, Barra V. Chromatin epigenetics and nuclear lamina keep the nucleus in shape: Examples from natural and accelerated aging. Biol Cell 2023; 115:e2200023. [PMID: 36117150 DOI: 10.1111/boc.202200023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 09/11/2022] [Accepted: 09/12/2022] [Indexed: 01/07/2023]
Abstract
As the repository of genetic information, the cell nucleus must protect DNA integrity from mechanical stresses. The nuclear lamina, which resides within the nuclear envelope (NE), is made up of lamins, intermediate filaments bound to DNA. The nuclear lamina provides the nucleus with the ability to deal with inward as well as outward mechanical stimuli. Chromatin, in turn, through its degrees of compaction, shares this role with the nuclear lamina, thus, ensuring the plasticity of the nucleus. Perturbation of chromatin condensation or the nuclear lamina has been linked to a plethora of biological conditions, that range from cancer and genetic diseases (laminopathies) to aging, both natural and accelerated, such as the case of Hutchinson-Gilford Progeria Syndrome (HGPS). From the experimental results accumulated so far on the topic, a direct link between variations of the epigenetic pattern and nuclear lamina structure would be suggested, however, it has never been clarified thoroughly. This relationship, instead, has a downstream important implication on nucleus shape, genome preservation, force sensing, and, ultimately, aging-related disease onset. With this review, we aim to collect recent studies on the importance of both nuclear lamina components and chromatin status in nuclear mechanics. We also aim to bring to light evidence of the link between DNA methylation and nuclear lamina in natural and accelerated aging.
Collapse
Affiliation(s)
- Pietro Salvatore Carollo
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Palermo, Italy
| | - Viviana Barra
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Palermo, Italy
| |
Collapse
|
3
|
Disney-Hogg L, Kinnersley B, Houlston R. Algorithmic considerations when analysing capture Hi-C data. Wellcome Open Res 2022; 5:289. [DOI: 10.12688/wellcomeopenres.16394.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2022] [Indexed: 11/13/2022] Open
Abstract
Chromosome conformation capture methodologies have provided insight into the effect of 3D genomic architecture on gene regulation. Capture Hi-C (CHi-C) is a recent extension of Hi-C that improves the effective resolution of chromatin interactions by enriching for defined regions of biological relevance. The varying targeting efficiency between capture regions, however, introduces bias not present in conventional Hi-C, making analysis more complicated. Here we consider salient features of an algorithm that should be considered in evaluating the performance of a program used to analyse CHi-C data in order to infer meaningful interactions. We use the program CHICAGO to analyse promoter capture Hi-C data generated on 28 different cell lines as a case study.
Collapse
|
4
|
CTCF-CTCF loops and intra-TAD interactions show differential dependence on cohesin ring integrity. Nat Cell Biol 2022; 24:1516-1527. [PMID: 36202971 PMCID: PMC10174090 DOI: 10.1038/s41556-022-00992-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 08/11/2022] [Indexed: 11/08/2022]
Abstract
The ring-like cohesin complex mediates sister-chromatid cohesion by encircling pairs of sister chromatids. Cohesin also extrudes loops along chromatids. Whether the two activities involve similar mechanisms of DNA engagement is not known. We implemented an experimental approach based on isolated nuclei carrying engineered cleavable RAD21 proteins to precisely control cohesin ring integrity so that its role in chromatin looping could be studied under defined experimental conditions. This approach allowed us to identify cohesin complexes with distinct biochemical, and possibly structural, properties that mediate different sets of chromatin loops. When RAD21 is cleaved and the cohesin ring is opened, cohesin complexes at CTCF sites are released from DNA and loops at these elements are lost. In contrast, cohesin-dependent loops within chromatin domains that are not anchored at pairs of CTCF sites are more resistant to RAD21 cleavage. The results show that the cohesin complex mediates loops in different ways depending on the genomic context and suggests that it undergoes structural changes as it dynamically extrudes and encounters CTCF sites.
Collapse
|
5
|
Ide S, Tamura S, Maeshima K. Chromatin behavior in living cells: Lessons from single‐nucleosome imaging and tracking. Bioessays 2022; 44:e2200043. [DOI: 10.1002/bies.202200043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 04/24/2022] [Accepted: 04/26/2022] [Indexed: 11/05/2022]
Affiliation(s)
- Satoru Ide
- Genome Dynamics Laboratory National Institute of Genetics, ROIS Mishima Shizuoka Japan
- Department of Genetics School of Life Science SOKENDAI Mishima Shizuoka Japan
| | - Sachiko Tamura
- Genome Dynamics Laboratory National Institute of Genetics, ROIS Mishima Shizuoka Japan
| | - Kazuhiro Maeshima
- Genome Dynamics Laboratory National Institute of Genetics, ROIS Mishima Shizuoka Japan
- Department of Genetics School of Life Science SOKENDAI Mishima Shizuoka Japan
| |
Collapse
|
6
|
Navarro EJ, Marshall WF, Fung JC. Modeling cell biological features of meiotic chromosome pairing to study interlock resolution. PLoS Comput Biol 2022; 18:e1010252. [PMID: 35696428 PMCID: PMC9232156 DOI: 10.1371/journal.pcbi.1010252] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 06/24/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022] Open
Abstract
During meiosis, homologous chromosomes become associated side by side in a process known as homologous chromosome pairing. Pairing requires long range chromosome motion through a nucleus that is full of other chromosomes. It remains unclear how the cell manages to align each pair of chromosomes quickly while mitigating and resolving interlocks. Here, we use a coarse-grained molecular dynamics model to investigate how specific features of meiosis, including motor-driven telomere motion, nuclear envelope interactions, and increased nuclear size, affect the rate of pairing and the mitigation/resolution of interlocks. By creating in silico versions of three yeast strains and comparing the results of our model to experimental data, we find that a more distributed placement of pairing sites along the chromosome is necessary to replicate experimental findings. Active motion of the telomeric ends speeds up pairing only if binding sites are spread along the chromosome length. Adding a meiotic bouquet significantly speeds up pairing but does not significantly change the number of interlocks. An increase in nuclear size slows down pairing while greatly reducing the number of interlocks. Interestingly, active forces increase the number of interlocks, which raises the question: How do these interlocks resolve? Our model gives us detailed movies of interlock resolution events which we then analyze to build a step-by-step recipe for interlock resolution. In our model, interlocks must first translocate to the ends, where they are held in a quasi-stable state by a large number of paired sites on one side. To completely resolve an interlock, the telomeres of the involved chromosomes must come in close proximity so that the cooperativity of pairing coupled with random motion causes the telomeres to unwind. Together our results indicate that computational modeling of homolog pairing provides insight into the specific cell biological changes that occur during meiosis.
Collapse
Affiliation(s)
- Erik J. Navarro
- Department of Obstetrics, Gynecology and Reproductive Sciences and Center of Reproductive Sciences, University of California, San Francisco, California, United States of America
| | - Wallace F. Marshall
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
| | - Jennifer C. Fung
- Department of Obstetrics, Gynecology and Reproductive Sciences and Center of Reproductive Sciences, University of California, San Francisco, California, United States of America
| |
Collapse
|
7
|
Sanders JT, Golloshi R, Das P, Xu Y, Terry PH, Nash DG, Dekker J, McCord RP. Loops, topologically associating domains, compartments, and territories are elastic and robust to dramatic nuclear volume swelling. Sci Rep 2022; 12:4721. [PMID: 35304523 PMCID: PMC8933507 DOI: 10.1038/s41598-022-08602-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 03/09/2022] [Indexed: 11/09/2022] Open
Abstract
Layers of genome organization are becoming increasingly better characterized, but less is known about how these structures respond to perturbation or shape changes. Low-salt swelling of isolated chromatin fibers or nuclei has been used for decades to investigate the structural properties of chromatin. But, visible changes in chromatin appearance have not been linked to known building blocks of genome structure or features along the genome sequence. We combine low-salt swelling of isolated nuclei with genome-wide chromosome conformation capture (Hi-C) and imaging approaches to probe the effects of chromatin extension genome-wide. Photoconverted patterns on nuclei during expansion and contraction indicate that global genome structure is preserved after dramatic nuclear volume swelling, suggesting a highly elastic chromosome topology. Hi-C experiments before, during, and after nuclear swelling show changes in average contact probabilities at short length scales, reflecting the extension of the local chromatin fiber. But, surprisingly, during this large increase in nuclear volume, there is a striking maintenance of loops, TADs, active and inactive compartments, and chromosome territories. Subtle differences after expansion are observed, suggesting that the local chromatin state, protein interactions, and location in the nucleus can affect how strongly a given structure is maintained under stress. From these observations, we propose that genome topology is robust to extension of the chromatin fiber and isotropic shape change, and that this elasticity may be beneficial in physiological circumstances of changes in nuclear size and volume.
Collapse
Affiliation(s)
- Jacob T Sanders
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Rosela Golloshi
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Priyojit Das
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
| | - Yang Xu
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
| | - Peyton H Terry
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Darrian G Nash
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Rachel Patton McCord
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA.
| |
Collapse
|
8
|
Whole-genome methods to define DNA and histone accessibility and long-range interactions in chromatin. Biochem Soc Trans 2022; 50:199-212. [PMID: 35166326 PMCID: PMC9847230 DOI: 10.1042/bst20210959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/30/2021] [Accepted: 01/24/2022] [Indexed: 02/08/2023]
Abstract
Defining the genome-wide chromatin landscape has been a goal of experimentalists for decades. Here we review highlights of these efforts, from seminal experiments showing discontinuities in chromatin structure related to gene activation to extensions of these methods elucidating general features of chromatin related to gene states by exploiting deep sequencing methods. We also review chromatin conformational capture methods to identify patterns in long-range interactions between genomic loci.
Collapse
|
9
|
Swygert SG, Lin D, Portillo-Ledesma S, Lin PY, Hunt DR, Kao CF, Schlick T, Noble WS, Tsukiyama T. Local chromatin fiber folding represses transcription and loop extrusion in quiescent cells. eLife 2021; 10:e72062. [PMID: 34734806 PMCID: PMC8598167 DOI: 10.7554/elife.72062] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/03/2021] [Indexed: 12/16/2022] Open
Abstract
A longstanding hypothesis is that chromatin fiber folding mediated by interactions between nearby nucleosomes represses transcription. However, it has been difficult to determine the relationship between local chromatin fiber compaction and transcription in cells. Further, global changes in fiber diameters have not been observed, even between interphase and mitotic chromosomes. We show that an increase in the range of local inter-nucleosomal contacts in quiescent yeast drives the compaction of chromatin fibers genome-wide. Unlike actively dividing cells, inter-nucleosomal interactions in quiescent cells require a basic patch in the histone H4 tail. This quiescence-specific fiber folding globally represses transcription and inhibits chromatin loop extrusion by condensin. These results reveal that global changes in chromatin fiber compaction can occur during cell state transitions, and establish physiological roles for local chromatin fiber folding in regulating transcription and chromatin domain formation.
Collapse
Affiliation(s)
- Sarah G Swygert
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Dejun Lin
- Department of Genome Sciences, University of WashingtonSeattleUnited States
| | | | - Po-Yen Lin
- Institute of Cellular and Organismic Biology, Academia SinicaTaipeiTaiwan
| | - Dakota R Hunt
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Cheng-Fu Kao
- Institute of Cellular and Organismic Biology, Academia SinicaTaipeiTaiwan
| | - Tamar Schlick
- Department of Chemistry, New York UniversityNew YorkUnited States
- Courant Institute of Mathematical Sciences, New York UniversityNew YorkUnited States
- New York University-East China Normal University Center for Computational Chemistry at New York University ShanghaiShanghaiChina
| | - William S Noble
- Department of Genome Sciences, University of WashingtonSeattleUnited States
- Paul G. Allen School of Computer Science and Engineering, University of WashingtonSeattleUnited States
| | - Toshio Tsukiyama
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
| |
Collapse
|
10
|
Gil L, Niño SA, Guerrero C, Jiménez-Capdeville ME. Phospho-Tau and Chromatin Landscapes in Early and Late Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms221910283. [PMID: 34638632 PMCID: PMC8509045 DOI: 10.3390/ijms221910283] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/17/2021] [Accepted: 09/18/2021] [Indexed: 12/25/2022] Open
Abstract
Cellular identity is determined through complex patterns of gene expression. Chromatin, the dynamic structure containing genetic information, is regulated through epigenetic modulators, mainly by the histone code. One of the main challenges for the cell is maintaining functionality and identity, despite the accumulation of DNA damage throughout the aging process. Replicative cells can remain in a senescent state or develop a malign cancer phenotype. In contrast, post-mitotic cells such as pyramidal neurons maintain extraordinary functionality despite advanced age, but they lose their identity. This review focuses on tau, a protein that protects DNA, organizes chromatin, and plays a crucial role in genomic stability. In contrast, tau cytosolic aggregates are considered hallmarks of Alzheimer´s disease (AD) and other neurodegenerative disorders called tauopathies. Here, we explain AD as a phenomenon of chromatin dysregulation directly involving the epigenetic histone code and a progressive destabilization of the tau–chromatin interaction, leading to the consequent dysregulation of gene expression. Although this destabilization could be lethal for post-mitotic neurons, tau protein mediates profound cellular transformations that allow for their temporal survival.
Collapse
Affiliation(s)
- Laura Gil
- Departamento de Genética, Escuela de Medicina, Universidad “Alfonso X el Sabio”, 28691 Madrid, Spain;
| | - Sandra A. Niño
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma, de San Luis Potosí 78210, Mexico;
| | - Carmen Guerrero
- Banco de Cerebros (Biobanco), Hospital Universitario Fundación Alcorcón, Alcorcón, 28922 Madrid, Spain;
| | - María E. Jiménez-Capdeville
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma, de San Luis Potosí 78210, Mexico;
- Correspondence: ; Tel.: +52-444-826-2366
| |
Collapse
|
11
|
Itoh Y, Woods EJ, Minami K, Maeshima K, Collepardo-Guevara R. Liquid-like chromatin in the cell: What can we learn from imaging and computational modeling? Curr Opin Struct Biol 2021; 71:123-135. [PMID: 34303931 DOI: 10.1016/j.sbi.2021.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 06/08/2021] [Indexed: 12/23/2022]
Abstract
Chromatin in eukaryotic cells is a negatively charged long polymer consisting of DNA, histones, and various associated proteins. With its highly charged and heterogeneous nature, chromatin structure varies greatly depending on various factors (e.g. chemical modifications and protein enrichment) and the surrounding environment (e.g. cations): from a 10-nm fiber, a folded 30-nm fiber, to chromatin condensates/droplets. Recent advanced imaging has observed that chromatin exhibits a dynamic liquid-like behavior and undergoes structural variations within the cell. Current computational modeling has made it possible to reconstruct the liquid-like chromatin in the cell by dealing with a number of nucleosomes on multiscale levels and has become a powerful technique to inspect the molecular mechanisms giving rise to the observed behavior, which imaging methods cannot do on their own. Based on new findings from both imaging and modeling studies, we discuss the dynamic aspect of chromatin in living cells and its functional relevance.
Collapse
Affiliation(s)
- Yuji Itoh
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Esmae J Woods
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
| | - Katsuhiko Minami
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan; Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan; Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan.
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK; Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK.
| |
Collapse
|
12
|
Ohno M, Ando T, Priest DG, Taniguchi Y. Hi-CO: 3D genome structure analysis with nucleosome resolution. Nat Protoc 2021; 16:3439-3469. [PMID: 34050337 DOI: 10.1038/s41596-021-00543-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 03/23/2021] [Indexed: 01/03/2023]
Abstract
The nucleosome is the basic organizational unit of the genome. The folding structure of nucleosomes is closely related to genome functions, and has been reported to be in dynamic interplay with binding of various nuclear proteins to genomic loci. Here, we describe our high-throughput chromosome conformation capture with nucleosome orientation (Hi-CO) technology to derive 3D nucleosome positions with their orientations at every genomic locus in the nucleus. This technology consists of an experimental procedure for nucleosome proximity analysis and a computational procedure for 3D modeling. The experimental procedure is based on an improved method of high-throughput chromosome conformation capture (Hi-C) analysis. Whereas conventional Hi-C allows spatial proximity analysis among genomic loci with 1-10 kbp resolution, our Hi-CO allows proximity analysis among DNA entry or exit points at every nucleosome locus. This analysis is realized by carrying out ligations among the entry/exit points in every nucleosome in a micrococcal-nuclease-fragmented genome, and by quantifying frequencies of ligation products with next-generation sequencing. Our protocol has enabled this analysis by cleanly excluding unwanted non-ligation products that are abundant owing to the frequent genome fragmentation by micrococcal nuclease. The computational procedure is based on simulated annealing-molecular dynamics, which allows determination of optimized 3D positions and orientations of every nucleosome that satisfies the proximity ligation data sufficiently well. Typically, examination of the Saccharomyces cerevisiae genome with 130 million sequencing reads facilitates analysis of a total of 66,360 nucleosome loci with 6.8 nm resolution. The technique requires 2-3 weeks for sequencing library preparation and 2 weeks for simulation.
Collapse
Affiliation(s)
- Masae Ohno
- Laboratory for Cell Systems Control, RIKEN Center for Biosystems Dynamics Research, Osaka, Japan.,Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto, Japan
| | - Tadashi Ando
- Laboratory for Biomolecular Function Simulation, Quantitative Biology Center, RIKEN, Kobe, Japan.,Department of Applied Electronics, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, Japan
| | - David G Priest
- Laboratory for Cell Systems Control, RIKEN Center for Biosystems Dynamics Research, Osaka, Japan.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Yuichi Taniguchi
- Laboratory for Cell Systems Control, RIKEN Center for Biosystems Dynamics Research, Osaka, Japan. .,Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto, Japan. .,Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
| |
Collapse
|
13
|
Abstract
Genomic information is encoded on long strands of DNA, which are folded into chromatin and stored in a tiny nucleus. Nuclear chromatin is a negatively charged polymer composed of DNA, histones, and various nonhistone proteins. Because of its highly charged nature, chromatin structure varies greatly depending on the surrounding environment (e.g., cations, molecular crowding, etc.). New technologies to capture chromatin in living cells have been developed over the past 10 years. Our view on chromatin organization has drastically shifted from a regular and static one to a more variable and dynamic one. Chromatin forms numerous compact dynamic domains that act as functional units of the genome in higher eukaryotic cells and locally appear liquid-like. By changing DNA accessibility, these domains can govern various functions. Based on new evidences from versatile genomics and advanced imaging studies, we discuss the physical nature of chromatin in the crowded nuclear environment and how it is regulated.
Collapse
Affiliation(s)
- Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Shiori Iida
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Sachiko Tamura
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| |
Collapse
|
14
|
Di Stefano M, Nützmann HW, Marti-Renom M, Jost D. Polymer modelling unveils the roles of heterochromatin and nucleolar organizing regions in shaping 3D genome organization in Arabidopsis thaliana. Nucleic Acids Res 2021; 49:1840-1858. [PMID: 33444439 PMCID: PMC7913674 DOI: 10.1093/nar/gkaa1275] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 11/16/2020] [Accepted: 01/13/2021] [Indexed: 01/10/2023] Open
Abstract
The 3D genome is characterized by a complex organization made of genomic and epigenomic layers with profound implications on gene regulation and cell function. However, the understanding of the fundamental mechanisms driving the crosstalk between nuclear architecture and (epi)genomic information is still lacking. The plant Arabidopsis thaliana is a powerful model organism to address these questions owing to its compact genome for which we have a rich collection of microscopy, chromosome conformation capture (Hi-C) and ChIP-seq experiments. Using polymer modelling, we investigate the roles of nucleolus formation and epigenomics-driven interactions in shaping the 3D genome of A. thaliana. By validation of several predictions with published data, we demonstrate that self-attracting nucleolar organizing regions and repulsive constitutive heterochromatin are major mechanisms to regulate the organization of chromosomes. Simulations also suggest that interphase chromosomes maintain a partial structural memory of the V-shapes, typical of (sub)metacentric chromosomes in anaphase. Additionally, self-attraction between facultative heterochromatin regions facilitates the formation of Polycomb bodies hosting H3K27me3-enriched gene-clusters. Since nucleolus and heterochromatin are highly-conserved in eukaryotic cells, our findings pave the way for a comprehensive characterization of the generic principles that are likely to shape and regulate the 3D genome in many species.
Collapse
Affiliation(s)
- Marco Di Stefano
- CNAG-CRG, The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Hans-Wilhelm Nützmann
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Marc A Marti-Renom
- CNAG-CRG, The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
- CRG, The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- ICREA, Barcelona, Spain
| | - Daniel Jost
- Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS, Laboratoire de Biologie et Modélisation de la Cellule, Lyon, France
| |
Collapse
|
15
|
Marr LT, Ocampo J, Clark DJ, Hayes JJ. Global histone protein surface accessibility in yeast indicates a uniformly loosely packed genome with canonical nucleosomes. Epigenetics Chromatin 2021; 14:5. [PMID: 33430969 PMCID: PMC7802155 DOI: 10.1186/s13072-020-00381-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/28/2020] [Indexed: 01/09/2023] Open
Abstract
Background The vast majority of methods available to characterize genome-wide chromatin structure exploit differences in DNA accessibility to nucleases or chemical crosslinking. We developed a novel method to gauge genome-wide accessibility of histone protein surfaces within nucleosomes by assessing reactivity of engineered cysteine residues with a thiol-specific reagent, biotin-maleimide (BM). Results Yeast nuclei were obtained from cells expressing the histone mutant H2B S116C, in which a cysteine resides near the center of the external flat protein surface of the nucleosome. BM modification revealed that nucleosomes are generally equivalently accessible throughout the S. cerevisiae genome, including heterochromatic regions, suggesting limited, higher-order chromatin structures in which this surface is obstructed by tight nucleosome packing. However, we find that nucleosomes within 500 bp of transcription start sites exhibit the greatest range of accessibility, which correlates with the density of chromatin remodelers. Interestingly, accessibility is not well correlated with RNA polymerase density and thus the level of gene expression. We also investigated the accessibility of cysteine mutations designed to detect exposure of histone surfaces internal to the nucleosome thought to be accessible in actively transcribed genes: H3 102, is at the H2A–H2B dimer/H3–H4 tetramer interface, and H3 A110C, resides at the H3–H3 interface. However, in contrast to the external surface site, we find that neither of these internal sites were found to be appreciably exposed. Conclusions Overall, our finding that nucleosomes surfaces within S. cerevisiae chromatin are equivalently accessible genome-wide is consistent with a globally uncompacted chromatin structure lacking substantial higher-order organization. However, we find modest differences in accessibility that correlate with chromatin remodelers but not transcription, suggesting chromatin poised for transcription is more accessible than actively transcribed or intergenic regions. In contrast, we find that two internal sites remain inaccessible, suggesting that such non-canonical nucleosome species generated during transcription are rapidly and efficiently converted to canonical nucleosome structure and thus not widely present in native chromatin.
Collapse
Affiliation(s)
- Luke T Marr
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Josefina Ocampo
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI-CONICET), C1428ADN, Buenos Aires, Argentina
| | - David J Clark
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
| | - Jeffrey J Hayes
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, 14642, USA.
| |
Collapse
|
16
|
Nand A, Zhan Y, Salazar OR, Aranda M, Voolstra CR, Dekker J. Genetic and spatial organization of the unusual chromosomes of the dinoflagellate Symbiodinium microadriaticum. Nat Genet 2021; 53:618-629. [PMID: 33927399 PMCID: PMC8110479 DOI: 10.1038/s41588-021-00841-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 03/09/2021] [Indexed: 02/02/2023]
Abstract
Dinoflagellates are main primary producers in the oceans, the cause of algal blooms and endosymbionts of marine invertebrates. Much remains to be understood about their biology, including their peculiar crystalline chromosomes. We assembled 94 chromosome-scale scaffolds of the genome of the coral endosymbiont Symbiodinium microadriaticum and analyzed their organization. Genes are enriched towards the ends of chromosomes and are arranged in alternating unidirectional blocks. Some chromosomes are enriched for genes involved in specific biological processes. The chromosomes fold as linear rods and each is composed of a series of structural domains separated by boundaries. Domain boundaries are positioned at sites where transcription of two gene blocks converges and disappear when cells are treated with chemicals that block transcription, indicating correlations between gene orientation, transcription and chromosome folding. The description of the genetic and spatial organization of the S. microadriaticum genome provides a foundation for deeper exploration of the extraordinary biology of dinoflagellates and their chromosomes.
Collapse
Affiliation(s)
- Ankita Nand
- grid.168645.80000 0001 0742 0364Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA USA
| | - Ye Zhan
- grid.168645.80000 0001 0742 0364Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA USA
| | - Octavio R. Salazar
- grid.45672.320000 0001 1926 5090Biological and Environmental Sciences & Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Manuel Aranda
- grid.45672.320000 0001 1926 5090Biological and Environmental Sciences & Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Christian R. Voolstra
- grid.9811.10000 0001 0658 7699Department of Biology, University of Konstanz, Konstanz, Germany
| | - Job Dekker
- grid.168645.80000 0001 0742 0364Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA USA ,grid.413575.10000 0001 2167 1581Howard Hughes Medical Institute, Chevy Chase, MD USA
| |
Collapse
|
17
|
Disney-Hogg L, Kinnersley B, Houlston R. Algorithmic considerations when analysing capture Hi-C data. Wellcome Open Res 2020; 5:289. [DOI: 10.12688/wellcomeopenres.16394.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2020] [Indexed: 01/11/2023] Open
Abstract
Chromosome conformation capture methodologies have provided insight into the effect of 3D genomic architecture on gene regulation. Capture Hi-C (CHi-C) is a recent extension of Hi-C that improves the effective resolution of chromatin interactions by enriching for defined regions of biological relevance. The varying targeting efficiency between capture regions, however, introduces bias not present in conventional Hi-C, making analysis more complicated. Here we consider salient features of an algorithm that should be considered in evaluating the performance of a program used to analyse CHi-C data in order to infer meaningful interactions. We use the program CHICAGO to analyse promotor capture Hi-C data generated on 28 different cell lines as a case study.
Collapse
|
18
|
Multi-contact 3C reveals that the human genome during interphase is largely not entangled. Nat Struct Mol Biol 2020; 27:1105-1114. [PMID: 32929283 PMCID: PMC7718335 DOI: 10.1038/s41594-020-0506-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 08/13/2020] [Indexed: 11/08/2022]
Abstract
During interphase the eukaryotic genome is organized into chromosome territories that are spatially segregated into compartment domains. The extent to which interacting domains or chromosomes are entangled is not known. We analyze series of co-occurring chromatin interactions using multi-contact 3C (MC-3C) in human cells to provide insights into the topological entanglement of chromatin. Multi-contact interactions represent percolation paths (C-walks) through 3D chromatin space. We find that the order of interactions within C-walks that occur across interfaces where chromosomes or compartment domains interact is not random. Polymer simulations show that such C-walks are consistent with distal domains being topologically insulated, i.e. not catenated. Simulations show that even low levels of random strand passage, e.g. by topoisomerase II, would result in entanglements, increased mixing at domain interfaces and an order of interactions within C-walks not consistent with experimental MC-3C data. Our results indicate that during interphase entanglements between chromosomes and chromosomal domains are rare.
Collapse
|
19
|
Chiang M, Michieletto D, Brackley CA, Rattanavirotkul N, Mohammed H, Marenduzzo D, Chandra T. Polymer Modeling Predicts Chromosome Reorganization in Senescence. Cell Rep 2020; 28:3212-3223.e6. [PMID: 31533042 PMCID: PMC6859504 DOI: 10.1016/j.celrep.2019.08.045] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 05/10/2019] [Accepted: 08/13/2019] [Indexed: 12/13/2022] Open
Abstract
Lamina-associated domains (LADs) cover a large part of the human genome and are thought to play a major role in shaping the nuclear architectural landscape. Here, we perform polymer simulations, microscopy, and mass spectrometry to dissect the roles played by heterochromatin- and lamina-mediated interactions in nuclear organization. Our model explains the conventional organization of heterochromatin and euchromatin in growing cells and the pathological organization found in oncogene-induced senescence and progeria. We show that the experimentally observed changes in the locality of contacts in senescent and progeroid cells can be explained as arising due to phase transitions in the system. Within our simulations, LADs are highly stochastic, as in experiments. Our model suggests that, once established, the senescent phenotype should be metastable even if lamina-mediated interactions were reinstated. Overall, our simulations uncover a generic physical mechanism that can regulate heterochromatin segregation and LAD formation in a wide range of mammalian nuclei.
Collapse
Affiliation(s)
- Michael Chiang
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK.
| | - Davide Michieletto
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK; MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK; Centre for Mathematical Biology, and Department of Mathematical Sciences, University of Bath, North Road, Bath BA2 7AY, UK
| | - Chris A Brackley
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - Nattaphong Rattanavirotkul
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK
| | - Hisham Mohammed
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute, Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Davide Marenduzzo
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - Tamir Chandra
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK.
| |
Collapse
|
20
|
Yeast ATM and ATR kinases use different mechanisms to spread histone H2A phosphorylation around a DNA double-strand break. Proc Natl Acad Sci U S A 2020; 117:21354-21363. [PMID: 32817543 PMCID: PMC7474660 DOI: 10.1073/pnas.2002126117] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
One of the hallmarks of DNA damage is the rapid spreading of phosphorylated histone H2A (γ-H2AX) around a DNA double-strand break (DSB). In the budding yeast Saccharomyces cerevisiae, nearly all H2A isoforms can be phosphorylated, either by Mec1ATR or Tel1ATM checkpoint kinases. We induced a site-specific DSB with HO endonuclease at the MAT locus on chromosome III and monitored the formation of γ-H2AX by chromatin immunoprecipitation (ChIP)-qPCR in order to uncover the mechanisms by which Mec1ATR and Tel1ATM propagate histone modifications across chromatin. With either kinase, γ-H2AX spreads as far as ∼50 kb on both sides of the lesion within 1 h; but the kinetics and distribution of modification around the DSB are significantly different. The total accumulation of phosphorylation is reduced by about half when either of the two H2A genes is mutated to the nonphosphorylatable S129A allele. Mec1 activity is limited by the abundance of its ATRIP partner, Ddc2. Moreover, Mec1 is more efficient than Tel1 at phosphorylating chromatin in trans-at distant undamaged sites that are brought into physical proximity to the DSB. We compared experimental data to mathematical models of spreading mechanisms to determine whether the kinases search for target nucleosomes by primarily moving in three dimensions through the nucleoplasm or in one dimension along the chromatin. Bayesian model selection indicates that Mec1 primarily uses a three-dimensional diffusive mechanism, whereas Tel1 undergoes directed motion along the chromatin.
Collapse
|
21
|
Maeshima K, Tamura S, Hansen JC, Itoh Y. Fluid-like chromatin: Toward understanding the real chromatin organization present in the cell. Curr Opin Cell Biol 2020; 64:77-89. [PMID: 32283330 DOI: 10.1016/j.ceb.2020.02.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/16/2020] [Accepted: 02/22/2020] [Indexed: 12/23/2022]
Abstract
Eukaryotic chromatin is a negatively charged polymer consisting of genomic DNA, histones, and various nonhistone proteins. Because of its highly charged character, the structure of chromatin varies greatly depending on the surrounding environment (i.e. cations etc.): from an extended 10-nm fiber, to a folded 30-nm fiber, to chromatin condensates/liquid-droplets. Over the last ten years, newly developed technologies have drastically shifted our view on chromatin from a static regular structure to a more irregular and dynamic one, locally like a fluid. Since no single imaging (or genomics) method can tell us everything and beautiful images (or models) can fool our minds, comprehensive analyses based on many technical approaches are important to capture actual chromatin organization inside the cell. Here we critically discuss our current view on chromatin and methodology used to support the view.
Collapse
Affiliation(s)
- Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan; Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka, 411-8540, Japan.
| | - Sachiko Tamura
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| | - Jeffrey C Hansen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Yuji Itoh
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| |
Collapse
|
22
|
Heterogeneous fluid-like movements of chromatin and their implications to transcription. Biophys Rev 2020; 12:461-468. [PMID: 32206982 DOI: 10.1007/s12551-020-00675-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 03/02/2020] [Indexed: 01/10/2023] Open
Abstract
Eukaryotic chromatin is a complex of genome DNA and associated proteins, and its structure and dynamics play a crucial role in regulating DNA functions. Chromatin takes rather irregular structures in the nucleus and exhibits heterogeneous sub-diffusive movements as polymers fluctuating in a fluid state. Using genome-wide single-nucleosome tracking data, heterogeneity of movements was statistically analyzed, which categorized chromatin into two types: slow chromatin that moves under structurally constrained environments and fast chromatin that moves with less constraints. Interactions of chromatin to various protein factors determine the motional constraints. For example, loss of the cohesin complex that bundles the chromatin chains reduces the motional constraints and increases the population of fast chromatin. Another example is the transcriptional machinery. While it was previously thought that the transcriptional activity is associated with more open and dynamic chromatin structure, recent studies suggested a more nuanced role of transcription in chromatin dynamics: dynamic association/dissociation of active RNA polymerase II (RNAPII) and other transcription factors and Mediators (TF-Meds) transiently bridges transcriptionally active DNA regions, which forms a loose network of chromatin and constrains chromatin movement, enhancing the slow chromatin population. This new view on the dynamical effects of transcription urges a reflection on the traditional model of transcription factories and invites the more recent models of condensates/phase-separated liquid droplets of RNAPII, transcription factors, and Mediators. The combined procedure of genome-wide single-nucleosome tracking and its statistical analysis would unveil heterogeneity in the chromatin movement, which should provide a key to understanding the relations among chromatin dynamics, structure, and function.
Collapse
|
23
|
Di Stefano M, Di Giovanni F, Pozharskaia V, Gomar-Alba M, Baù D, Carey LB, Marti-Renom MA, Mendoza M. Impact of Chromosome Fusions on 3D Genome Organization and Gene Expression in Budding Yeast. Genetics 2020; 214:651-667. [PMID: 31907200 PMCID: PMC7054015 DOI: 10.1534/genetics.119.302978] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/01/2020] [Indexed: 12/03/2022] Open
Abstract
The three-dimensional (3D) organization of chromosomes can influence transcription. However, the frequency and magnitude of these effects remain debated. To determine how changes in chromosome positioning affect transcription across thousands of genes with minimal perturbation, we characterized nuclear organization and global gene expression in budding yeast containing chromosome fusions. We used computational modeling and single-cell imaging to determine chromosome positions, and integrated these data with genome-wide transcriptional profiles from RNA sequencing. We find that chromosome fusions dramatically alter 3D nuclear organization without leading to strong genome-wide changes in transcription. However, we observe a mild but significant and reproducible increase in the expression of genes displaced away from the periphery. The increase in transcription is inversely proportional to the propensity of a given locus to be at the nuclear periphery; for example, a 10% decrease in the propensity of a gene to reside at the nuclear envelope is accompanied by a 10% increase in gene expression. Modeling suggests that this is due to both deletion of telomeres and to displacement of genes relative to the nuclear periphery. These data suggest that basal transcriptional activity is sensitive to radial changes in gene position, and provide insight into the functional relevance of budding yeast chromosome-level 3D organization in gene expression.
Collapse
Affiliation(s)
- Marco Di Stefano
- CNAG-CRG, The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain
| | - Francesca Di Giovanni
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain
| | - Vasilisa Pozharskaia
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France
- Université de Strasbourg, 67000 Strasbourg, France
| | - Mercè Gomar-Alba
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France
- Université de Strasbourg, 67000 Strasbourg, France
| | - Davide Baù
- CNAG-CRG, The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain
| | - Lucas B Carey
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, 100871 Beijing, China
- Peking-Tsinghua Center for the Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, 100871 Beijing, China
| | - Marc A Marti-Renom
- CNAG-CRG, The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
- ICREA, 08010 Barcelona, Spain
| | - Manuel Mendoza
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France
- Université de Strasbourg, 67000 Strasbourg, France
- Universitat Pompeu Fabra (UPF), 08002 Barcelona, Spain
| |
Collapse
|
24
|
Babokhov M, Hibino K, Itoh Y, Maeshima K. Local Chromatin Motion and Transcription. J Mol Biol 2020; 432:694-700. [DOI: 10.1016/j.jmb.2019.10.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 10/07/2019] [Accepted: 10/24/2019] [Indexed: 12/17/2022]
|
25
|
|
26
|
Methods for mapping three-dimensional genome architecture. Methods 2020; 170:1-3. [PMID: 31669352 DOI: 10.1016/j.ymeth.2019.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
27
|
Kharerin H, Bhat PJ, Padinhateeri R. Role of nucleosome positioning in 3D chromatin organization and loop formation. J Biosci 2020; 45:14. [PMID: 31965992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We present a physics-based polymer model that can investigate 3D organization of chromatin accounting for DNA elasticity, DNA-bending due to nucleosomes, and 1D organization of nucleosomes along DNA. We find that the packing density of chromatin oscillates between densities corresponding to highly folded and extended configurations as we change the nucleosome organization (length of linker DNA). We compute the looping probability of chromatin and show that the presence of nucleosomes increases the looping probability of the chain compared to that of a bare DNA. We also show that looping probability has a large variability depending on the nature of nucleosome organization and density of linker histones.
Collapse
Affiliation(s)
- Hungyo Kharerin
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | | | | |
Collapse
|
28
|
Q-Nuc: a bioinformatics pipeline for the quantitative analysis of nucleosomal profiles. Interdiscip Sci 2019; 12:69-81. [PMID: 31845186 DOI: 10.1007/s12539-019-00354-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/20/2019] [Accepted: 11/22/2019] [Indexed: 12/26/2022]
Abstract
Nucleosomal profiling is an effective method to determine the positioning and occupancy of nucleosomes, which is essential to understand their roles in genomic processes. However, the positional randomness across the genome and its relationship with nucleosome occupancy remains poorly understood. Here we present a computational method that segments the profile into nucleosomal domains and quantifies their randomness and relative occupancy level. Applying this method to published data, we find on average ~ 3-fold differences in the degree of positional randomness between regions typically considered "well-ordered", as well as an unexpected predominance of only two types of domains of positional randomness in yeast cells. Further, we find that occupancy levels between domains actually differ maximally by ~ 2-3-fold in both cells, which has not been described before. We also developed a procedure by which one can estimate the sequencing depth that is required to identify nucleosomal positions even when regional positional randomness is high. Overall, we have developed a pipeline to quantitatively characterize domain-level features of nucleosome randomness and occupancy genome-wide, enabling the identification of otherwise unknown features in nucleosomal organization.
Collapse
|
29
|
Abstract
Maintaining the integrity of the genome in the face of DNA damage is crucial to ensure the survival of the cell and normal development. DNA lesions and repair occur in the context of the chromatin fiber, whose 3D organization and movements in the restricted volume of the nucleus are under intense scrutiny. Here, we highlight work from our and other labs that addresses how the dynamic organization of the chromatin fiber affects the repair of damaged DNA and how, conversely, DNA damage and repair affect the structure and dynamics of chromatin in the budding yeast nucleus.
Collapse
Affiliation(s)
- Emmanuelle Fabre
- a Equipe Biologie et Dynamique des Chromosomes , Institut Universitaire d'Hématologie, Hôpital St. Louis , Paris , France.,b CNRS, UMR 7212 INSERM U944, IUH, Université Paris Diderot Sorbonne Paris Cité , Paris , France
| | - Christophe Zimmer
- c Institut Pasteur, Unité Imagerie et Modélisation , 25 rue du Docteur Roux, 75015 , Paris , France.,d UMR 3691, CNRS; C3BI, USR 3756, IP CNRS , Paris , France
| |
Collapse
|
30
|
Walker B, Taylor D, Lawrimore J, Hult C, Adalsteinsson D, Bloom K, Forest MG. Transient crosslinking kinetics optimize gene cluster interactions. PLoS Comput Biol 2019; 15:e1007124. [PMID: 31433796 PMCID: PMC6730938 DOI: 10.1371/journal.pcbi.1007124] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/06/2019] [Accepted: 07/18/2019] [Indexed: 02/05/2023] Open
Abstract
Our understanding of how chromosomes structurally organize and dynamically interact has been revolutionized through the lens of long-chain polymer physics. Major protein contributors to chromosome structure and dynamics are condensin and cohesin that stochastically generate loops within and between chains, and entrap proximal strands of sister chromatids. In this paper, we explore the ability of transient, protein-mediated, gene-gene crosslinks to induce clusters of genes, thereby dynamic architecture, within the highly repeated ribosomal DNA that comprises the nucleolus of budding yeast. We implement three approaches: live cell microscopy; computational modeling of the full genome during G1 in budding yeast, exploring four decades of timescales for transient crosslinks between 5kbp domains (genes) in the nucleolus on Chromosome XII; and, temporal network models with automated community (cluster) detection algorithms applied to the full range of 4D modeling datasets. The data analysis tools detect and track gene clusters, their size, number, persistence time, and their plasticity (deformation). Of biological significance, our analysis reveals an optimal mean crosslink lifetime that promotes pairwise and cluster gene interactions through "flexible" clustering. In this state, large gene clusters self-assemble yet frequently interact (merge and separate), marked by gene exchanges between clusters, which in turn maximizes global gene interactions in the nucleolus. This regime stands between two limiting cases each with far less global gene interactions: with shorter crosslink lifetimes, "rigid" clustering emerges with clusters that interact infrequently; with longer crosslink lifetimes, there is a dissolution of clusters. These observations are compared with imaging experiments on a normal yeast strain and two condensin-modified mutant cell strains. We apply the same image analysis pipeline to the experimental and simulated datasets, providing support for the modeling predictions.
Collapse
Affiliation(s)
- Benjamin Walker
- Department of Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Dane Taylor
- Department of Mathematics, University at Buffalo, State University of New York, Buffalo, New York, United States of America
- Computational and Data Enabled Science and Engineering, University at Buffalo, State University of New York, Buffalo, New York, United States of America
| | - Josh Lawrimore
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Caitlin Hult
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - David Adalsteinsson
- Department of Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - M. Gregory Forest
- Department of Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Departments of Applied Physical Sciences and Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
31
|
Socol M, Wang R, Jost D, Carrivain P, Vaillant C, Le Cam E, Dahirel V, Normand C, Bystricky K, Victor JM, Gadal O, Bancaud A. Rouse model with transient intramolecular contacts on a timescale of seconds recapitulates folding and fluctuation of yeast chromosomes. Nucleic Acids Res 2019; 47:6195-6207. [PMID: 31114898 PMCID: PMC6614813 DOI: 10.1093/nar/gkz374] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/25/2019] [Accepted: 05/09/2019] [Indexed: 01/08/2023] Open
Abstract
DNA folding and dynamics along with major nuclear functions are determined by chromosome structural properties, which remain, thus far, elusive in vivo. Here, we combine polymer modeling and single particle tracking experiments to determine the physico-chemical parameters of chromatin in vitro and in living yeast. We find that the motion of reconstituted chromatin fibers can be recapitulated by the Rouse model using mechanical parameters of nucleosome arrays deduced from structural simulations. Conversely, we report that the Rouse model shows some inconsistencies to analyze the motion and structural properties inferred from yeast chromosomes determined with chromosome conformation capture techniques (specifically, Hi-C). We hence introduce the Rouse model with Transient Internal Contacts (RouseTIC), in which random association and dissociation occurs along the chromosome contour. The parametrization of this model by fitting motion and Hi-C data allows us to measure the kinetic parameters of the contact formation reaction. Chromosome contacts appear to be transient; associated to a lifetime of seconds and characterized by an attractive energy of -0.3 to -0.5 kBT. We suggest attributing this energy to the occurrence of histone tail-DNA contacts and notice that its amplitude sets chromosomes in 'theta' conditions, in which they are poised for compartmentalization and phase separation.
Collapse
Affiliation(s)
- Marius Socol
- LAAS-CNRS, Université de Toulouse, CNRS, F-31400 Toulouse, France
- IRIM, CNRS, University of Montpellier, France
| | - Renjie Wang
- Laboratoire de Biologie Moléculaire Eucaryote (LBME), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, F-31062 Toulouse, France
- Material Science & Engineering School, Henan University of Technology, 450001 Zhengzhou, P.R. China
| | - Daniel Jost
- Univ. Grenoble Alpes, CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, F-38000 Grenoble, France
| | - Pascal Carrivain
- Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS UMR 5672, Lyon 69007, France
| | - Cédric Vaillant
- Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS UMR 5672, Lyon 69007, France
| | - Eric Le Cam
- Genome Maintenance and Molecular Microscopy UMR8126, CNRS, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy, F-94805 Villejuif Cedex France
| | - Vincent Dahirel
- Sorbonne Université, CNRS, Physicochimie des Electrolytes et Nanosystèmes interfaciaux, laboratoire PHENIX, F-75005 Paris, France
| | - Christophe Normand
- Laboratoire de Biologie Moléculaire Eucaryote (LBME), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, F-31062 Toulouse, France
| | - Kerstin Bystricky
- Laboratoire de Biologie Moléculaire Eucaryote (LBME), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, F-31062 Toulouse, France
| | - Jean-Marc Victor
- Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensée, LPTMC, F-75005 Paris, France
| | - Olivier Gadal
- Laboratoire de Biologie Moléculaire Eucaryote (LBME), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, F-31062 Toulouse, France
| | - Aurélien Bancaud
- LAAS-CNRS, Université de Toulouse, CNRS, F-31400 Toulouse, France
| |
Collapse
|
32
|
Polymer coil-globule phase transition is a universal folding principle of Drosophila epigenetic domains. Epigenetics Chromatin 2019; 12:28. [PMID: 31084607 PMCID: PMC6515630 DOI: 10.1186/s13072-019-0269-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/06/2019] [Indexed: 01/02/2023] Open
Abstract
Background Localized functional domains within chromosomes, known as topologically associating domains (TADs), have been recently highlighted. In Drosophila, TADs are biochemically defined by epigenetic marks, this suggesting that the 3D arrangement may be the “missing link” between epigenetics and gene activity. Recent observations (Boettiger et al. in Nature 529(7586):418–422, 2016) provide access to structural features of these domains with unprecedented resolution thanks to super-resolution experiments. In particular, they give access to the distribution of the radii of gyration for domains of different linear length and associated with different transcriptional activity states: active, inactive or repressed. Intriguingly, the observed scaling laws lack consistent interpretation in polymer physics. Results We develop a new methodology conceived to extract the best information from such super-resolution data by exploiting the whole distribution of gyration radii, and to place these experimental results on a theoretical framework. We show that the experimental data are compatible with the finite-size behavior of a self-attracting polymer. The same generic polymer model leads to quantitative differences between active, inactive and repressed domains. Active domains behave as pure polymer coils, while inactive and repressed domains both lie at the coil–globule crossover. For the first time, the “color-specificity” of both the persistence length and the mean interaction energy are estimated, leading to important differences between epigenetic states. Conclusion These results point toward a crucial role of criticality to enhance the system responsivity, resulting in both energy transitions and structural rearrangements. We get strong indications that epigenetically induced changes in nucleosome–nucleosome interaction can cause chromatin to shift between different activity states. Electronic supplementary material The online version of this article (10.1186/s13072-019-0269-6) contains supplementary material, which is available to authorized users.
Collapse
|
33
|
Marshall WF, Fung JC. Modeling meiotic chromosome pairing: a tug of war between telomere forces and a pairing-based Brownian ratchet leads to increased pairing fidelity. Phys Biol 2019; 16:046005. [PMID: 30943453 DOI: 10.1088/1478-3975/ab15a7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Meiotic homolog pairing involves associations between homologous DNA regions scattered along the length of a chromosome. When homologs associate, they tend to do so by a processive zippering process, which apparently results from avidity effects. Using a computational model, we show that this avidity-driven processive zippering reduces the selectivity of pairing. When active random forces are applied to telomeres, this drop in selectivity is eliminated in a force-dependent manner. Further simulations suggest that active telomere forces are engaged in a tug-of-war against zippering, which can be interpreted as a Brownian ratchet with a stall force that depends on the dissociation constant of pairing. When perfectly homologous regions of high affinity compete with homeologous regions of lower affinity, the affinity difference can be amplified through this tug of war effect provided the telomere force acts in a range that is strong enough to oppose zippering of homeologs while still permitting zippering of correct homologs. The degree of unzippering depends on the radius of the nucleus, such that complete unzippering of homeologous regions can only take place if the nucleus is large enough to pull the two chromosomes completely apart. A picture of meiotic pairing thus emerges that is fundamentally mechanical in nature, possibly explaining the purpose of active telomere forces, increased nuclear diameter, and the presence of 'Maverick' chromosomes in meiosis.
Collapse
Affiliation(s)
- Wallace F Marshall
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, United States of America. Center for Cellular Construction, University of California San Francisco, San Francisco, CA, United States of America
| | | |
Collapse
|
34
|
Ohno M, Ando T, Priest DG, Kumar V, Yoshida Y, Taniguchi Y. Sub-nucleosomal Genome Structure Reveals Distinct Nucleosome Folding Motifs. Cell 2019; 176:520-534.e25. [DOI: 10.1016/j.cell.2018.12.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 10/16/2018] [Accepted: 12/09/2018] [Indexed: 12/11/2022]
|
35
|
Abstract
Predicting how epigenetic marks control the 3D organization of the genome is key to understanding how these marks regulate gene expression. We show that a physical model of a chromosome with experimentally measured local interactions segregates into euchromatin- and heterochromatin-like phases. The model reproduces many of the features of the large-scale organization of the chromosome as measured by Hi-C. Our work provides an estimate of the amount of epigenetic marking needed to segregate a gene into heterochromatin. We use a chromosome-scale simulation to show that the preferential binding of heterochromatin protein 1 (HP1) to regions high in histone methylation (specifically H3K9me3) results in phase segregation and reproduces features of the observed Hi-C contact map. Specifically, we perform Monte Carlo simulations with one computational bead per nucleosome and an H3K9me3 pattern based on published ChIP-seq signals. We implement a binding model in which HP1 preferentially binds to trimethylated histone tails and then oligomerizes to bridge together nucleosomes. We observe a phase reminiscent of heterochromatin—dense and high in H3K9me3—and another reminiscent of euchromatin—less dense and lacking H3K9me3. This segregation results in a plaid contact probability map that matches the general shape and position of published Hi-C data. Analysis suggests that a roughly 20-kb segment of H3K9me3 enrichment is required to drive segregation into the heterochromatic phase.
Collapse
|
36
|
Brown JM, Roberts NA, Graham B, Waithe D, Lagerholm C, Telenius JM, De Ornellas S, Oudelaar AM, Scott C, Szczerbal I, Babbs C, Kassouf MT, Hughes JR, Higgs DR, Buckle VJ. A tissue-specific self-interacting chromatin domain forms independently of enhancer-promoter interactions. Nat Commun 2018; 9:3849. [PMID: 30242161 PMCID: PMC6155075 DOI: 10.1038/s41467-018-06248-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 08/24/2018] [Indexed: 11/08/2022] Open
Abstract
Self-interacting chromatin domains encompass genes and their cis-regulatory elements; however, the three-dimensional form a domain takes, whether this relies on enhancer-promoter interactions, and the processes necessary to mediate the formation and maintenance of such domains, remain unclear. To examine these questions, here we use a combination of high-resolution chromosome conformation capture, a non-denaturing form of fluorescence in situ hybridisation and super-resolution imaging to study a 70 kb domain encompassing the mouse α-globin regulatory locus. We show that this region forms an erythroid-specific, decompacted, self-interacting domain, delimited by frequently apposed CTCF/cohesin binding sites early in terminal erythroid differentiation, and does not require transcriptional elongation for maintenance of the domain structure. Formation of this domain does not rely on interactions between the α-globin genes and their major enhancers, suggesting a transcription-independent mechanism for establishment of the domain. However, absence of the major enhancers does alter internal domain interactions. Formation of a loop domain therefore appears to be a mechanistic process that occurs irrespective of the specific interactions within.
Collapse
Affiliation(s)
- Jill M Brown
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Nigel A Roberts
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Bryony Graham
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Dominic Waithe
- Wolfson Imaging Centre Oxford, MRC Weatherall Institute of Molecular Medicine, Oxford, OX3 9DS, UK
| | - Christoffer Lagerholm
- Wolfson Imaging Centre Oxford, MRC Weatherall Institute of Molecular Medicine, Oxford, OX3 9DS, UK
| | - Jelena M Telenius
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Sara De Ornellas
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - A Marieke Oudelaar
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Caroline Scott
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Izabela Szczerbal
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
- Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637 Poznan, Poland
| | - Christian Babbs
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Mira T Kassouf
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Jim R Hughes
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Douglas R Higgs
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - Veronica J Buckle
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Oxford University, Oxford, OX3 9DS, UK.
| |
Collapse
|
37
|
Orlando G, Kinnersley B, Houlston RS. Capture Hi-C Library Generation and Analysis to Detect Chromatin Interactions. CURRENT PROTOCOLS IN HUMAN GENETICS 2018; 98:e63. [PMID: 29979818 DOI: 10.1002/cphg.63] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Chromosome conformation capture (3C), coupled with next-generation sequencing (Hi-C), provides a means for deciphering not only the principles underlying genome folding and architecture, but more broadly, the role 3D chromatin structure plays in gene regulation and the replication and repair of DNA. The recently implemented modification, in situ Hi-C, maintains nuclear integrity during digestion and ligation steps, reducing random ligation of Hi-C fragments. Although Hi-C allows for genome-wide characterization of chromatin contacts, it requires high-depth sequencing to discover significant contacts. To address this, Capture Hi-C (CHi-C) enriches standard Hi-C libraries for regions of biological interest, for example by specifically targeting gene promoters, aiding identification of biologically significant chromatin interactions compared to conventional Hi-C, for an equivalent number of sequence reads. Illustrating the application of CHi-C applied to genome-wide analysis of chromatin interactions with promoters, we detail the protocols for in situ Hi-C and CHi-C library generation for sequencing, as well as the bioinformatics tools for data analysis. © 2018 by John Wiley & Sons, Inc.
Collapse
Affiliation(s)
- Giulia Orlando
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London, United Kingdom
| | - Ben Kinnersley
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London, United Kingdom
| | - Richard S Houlston
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London, United Kingdom
| |
Collapse
|
38
|
Abstract
Chromatin is organized into higher-order structures that form subcompartments in interphase nuclei. Different categories of specialized enzymes act on chromatin and regulate its compaction and biophysical characteristics in response to physiological conditions. We present an overview of the function of chromatin structure and its dynamic changes in response to genotoxic stress, focusing on both subnuclear organization and the physical mobility of DNA. We review the requirements and mechanisms that cause chromatin relocation, enhanced mobility, and chromatin unfolding as a consequence of genotoxic lesions. An intriguing link has been established recently between enhanced chromatin dynamics and histone loss.
Collapse
Affiliation(s)
- Michael H Hauer
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| |
Collapse
|
39
|
Schalbetter SA, Goloborodko A, Fudenberg G, Belton JM, Miles C, Yu M, Dekker J, Mirny L, Baxter J. SMC complexes differentially compact mitotic chromosomes according to genomic context. Nat Cell Biol 2017; 19:1071-1080. [PMID: 28825700 PMCID: PMC5640152 DOI: 10.1038/ncb3594] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/19/2017] [Indexed: 12/26/2022]
Abstract
Structural maintenance of chromosomes (SMC) protein complexes are key determinants of chromosome conformation. Using Hi-C and polymer modelling, we study how cohesin and condensin, two deeply conserved SMC complexes, organize chromosomes in the budding yeast Saccharomyces cerevisiae. The canonical role of cohesin is to co-align sister chromatids, while condensin generally compacts mitotic chromosomes. We find strikingly different roles for the two complexes in budding yeast mitosis. First, cohesin is responsible for compacting mitotic chromosome arms, independently of sister chromatid cohesion. Polymer simulations demonstrate that this role can be fully accounted for through cis-looping of chromatin. Second, condensin is generally dispensable for compaction along chromosome arms. Instead, it plays a targeted role compacting the rDNA proximal regions and promoting resolution of peri-centromeric regions. Our results argue that the conserved mechanism of SMC complexes is to form chromatin loops and that distinct SMC-dependent looping activities are selectively deployed to appropriately compact chromosomes.
Collapse
MESH Headings
- Adenosine Triphosphatases/genetics
- Adenosine Triphosphatases/metabolism
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Chromatin/chemistry
- Chromatin/genetics
- Chromatin/metabolism
- Chromatin Assembly and Disassembly
- Chromosomal Proteins, Non-Histone/genetics
- Chromosomal Proteins, Non-Histone/metabolism
- Chromosome Structures
- Chromosomes, Fungal/chemistry
- Chromosomes, Fungal/genetics
- Chromosomes, Fungal/metabolism
- Computer Simulation
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Fungal/metabolism
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- DNA, Ribosomal/metabolism
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Mitosis
- Models, Genetic
- Models, Molecular
- Multiprotein Complexes/genetics
- Multiprotein Complexes/metabolism
- Nucleic Acid Conformation
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/growth & development
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Structure-Activity Relationship
- Cohesins
Collapse
Affiliation(s)
| | - Anton Goloborodko
- Institute for Medical Engineering and Sciences, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Geoffrey Fudenberg
- Institute for Medical Engineering and Sciences, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jon-Matthew Belton
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Catrina Miles
- Genome Damage and Stability Centre, Science Park Road, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Miao Yu
- Genome Damage and Stability Centre, Science Park Road, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Job Dekker
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Leonid Mirny
- Institute for Medical Engineering and Sciences, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jonathan Baxter
- Genome Damage and Stability Centre, Science Park Road, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| |
Collapse
|
40
|
Spichal M, Fabre E. The Emerging Role of the Cytoskeleton in Chromosome Dynamics. Front Genet 2017; 8:60. [PMID: 28580009 PMCID: PMC5437106 DOI: 10.3389/fgene.2017.00060] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 04/28/2017] [Indexed: 01/15/2023] Open
Abstract
Chromosomes underlie a dynamic organization that fulfills functional roles in processes like transcription, DNA repair, nuclear envelope stability, and cell division. Chromosome dynamics depend on chromosome structure and cannot freely diffuse. Furthermore, chromosomes interact closely with their surrounding nuclear environment, which further constrains chromosome dynamics. Recently, several studies enlighten that cytoskeletal proteins regulate dynamic chromosome organization. Cytoskeletal polymers that include actin filaments, microtubules and intermediate filaments can connect to the nuclear envelope via Linker of the Nucleoskeleton and Cytoskeleton (LINC) complexes and transfer forces onto chromosomes inside the nucleus. Monomers of these cytoplasmic polymers and related proteins can also enter the nucleus and play different roles in the interior of the nucleus than they do in the cytoplasm. Nuclear cytoskeletal proteins can act as chromatin remodelers alone or in complexes with other nuclear proteins. They can also act as transcription factors. Many of these mechanisms have been conserved during evolution, indicating that the cytoskeletal regulation of chromosome dynamics is an essential process. In this review, we discuss the different influences of cytoskeletal proteins on chromosome dynamics by focusing on the well-studied model organism budding yeast.
Collapse
Affiliation(s)
- Maya Spichal
- Department of Genetics, University of North Carolina, Chapel HillNC, United States
| | - Emmanuelle Fabre
- Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, CNRS UMR 7212, INSERM U944, Hôpital St. Louis 1Paris, France
| |
Collapse
|
41
|
Arbona JM, Herbert S, Fabre E, Zimmer C. Inferring the physical properties of yeast chromatin through Bayesian analysis of whole nucleus simulations. Genome Biol 2017; 18:81. [PMID: 28468672 PMCID: PMC5414205 DOI: 10.1186/s13059-017-1199-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 03/23/2017] [Indexed: 01/06/2023] Open
Abstract
Background The structure and mechanical properties of chromatin impact DNA functions and nuclear architecture but remain poorly understood. In budding yeast, a simple polymer model with minimal sequence-specific constraints and a small number of structural parameters can explain diverse experimental data on nuclear architecture. However, how assumed chromatin properties affect model predictions was not previously systematically investigated. Results We used hundreds of dynamic chromosome simulations and Bayesian inference to determine chromatin properties consistent with an extensive dataset that includes hundreds of measurements from imaging in fixed and live cells and two Hi-C studies. We place new constraints on average chromatin fiber properties, narrowing down the chromatin compaction to ~53–65 bp/nm and persistence length to ~52–85 nm. These constraints argue against a 20–30 nm fiber as the exclusive chromatin structure in the genome. Our best model provides a much better match to experimental measurements of nuclear architecture and also recapitulates chromatin dynamics measured on multiple loci over long timescales. Conclusion This work substantially improves our understanding of yeast chromatin mechanics and chromosome architecture and provides a new analytic framework to infer chromosome properties in other organisms. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1199-x) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jean-Michel Arbona
- Unité Imagerie et Modélisation, Institut Pasteur, 25 rue du Docteur Roux, 75015, Paris, France.,UMR 3691, CNRS; C3BI, USR 3756, IP CNRS, Paris, France
| | - Sébastien Herbert
- Unité Imagerie et Modélisation, Institut Pasteur, 25 rue du Docteur Roux, 75015, Paris, France.,UMR 3691, CNRS; C3BI, USR 3756, IP CNRS, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, 75015, Paris, France
| | - Emmanuelle Fabre
- Chromosome Biology and Dynamics, Hôpital Saint Louis, Paris, France
| | - Christophe Zimmer
- Unité Imagerie et Modélisation, Institut Pasteur, 25 rue du Docteur Roux, 75015, Paris, France. .,UMR 3691, CNRS; C3BI, USR 3756, IP CNRS, Paris, France.
| |
Collapse
|
42
|
du Preez LL, Patterton HG. The effect of epigenetic modifications on the secondary structures and possible binding positions of the N-terminal tail of histone H3 in the nucleosome: a computational study. J Mol Model 2017; 23:137. [PMID: 28353152 PMCID: PMC5391383 DOI: 10.1007/s00894-017-3308-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/06/2017] [Indexed: 11/05/2022]
Abstract
The roles of histone tails as substrates for reversible chemical modifications and dynamic cognate surfaces for the binding of regulatory proteins are well established. Despite these crucial roles, experimentally derived knowledge of the structure and possible binding sites of histone tails in chromatin is limited. In this study, we utilized molecular dynamics of isolated histone H3 N-terminal peptides to investigate its structure as a function of post-translational modifications that are known to be associated with defined chromatin states. We observed a structural preference for α-helices in isoforms associated with an inactive chromatin state, while isoforms associated with active chromatin states lacked α-helical content. The physicochemical effect of the post-translational modifications was highlighted by the interaction of arginine side-chains with the phosphorylated serine residues in the inactive isoform. We also showed that the isoforms exhibit different tail lengths, and, using molecular docking of the first 15 N-terminal residues of an H3 isoform, identified potential binding sites between the superhelical gyres on the octamer surface, close to the site of DNA entry/exit in the nucleosome. We discuss the possible functional role of the binding of the H3 tail within the nucleosome on both nucleosome and chromatin structure and stability.
Collapse
Affiliation(s)
- Louis L du Preez
- Department of Microbiological, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein, 9301, South Africa
| | - Hugh-G Patterton
- Division of Bioinformatics and Department of Biochemistry, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
| |
Collapse
|
43
|
Abstract
Chromosomes underlie a dynamic organization that fulfills functional roles in processes like transcription, DNA repair, nuclear envelope stability, and cell division. Chromosome dynamics depend on chromosome structure and cannot freely diffuse. Furthermore, chromosomes interact closely with their surrounding nuclear environment, which further constrains chromosome dynamics. Recently, several studies enlighten that cytoskeletal proteins regulate dynamic chromosome organization. Cytoskeletal polymers that include actin filaments, microtubules and intermediate filaments can connect to the nuclear envelope via Linker of the Nucleoskeleton and Cytoskeleton (LINC) complexes and transfer forces onto chromosomes inside the nucleus. Monomers of these cytoplasmic polymers and related proteins can also enter the nucleus and play different roles in the interior of the nucleus than they do in the cytoplasm. Nuclear cytoskeletal proteins can act as chromatin remodelers alone or in complexes with other nuclear proteins. They can also act as transcription factors. Many of these mechanisms have been conserved during evolution, indicating that the cytoskeletal regulation of chromosome dynamics is an essential process. In this review, we discuss the different influences of cytoskeletal proteins on chromosome dynamics by focusing on the well-studied model organism budding yeast.
Collapse
Affiliation(s)
- Maya Spichal
- Department of Genetics, University of North Carolina, Chapel HillNC, United States
| | - Emmanuelle Fabre
- Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, CNRS UMR 7212, INSERM U944, Hôpital St. Louis 1Paris, France
| |
Collapse
|
44
|
Tokuda N, Sasai M. Heterogeneous Spatial Distribution of Transcriptional Activity in Budding Yeast Nuclei. Biophys J 2016; 112:491-504. [PMID: 28040197 PMCID: PMC5300786 DOI: 10.1016/j.bpj.2016.11.3201] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/23/2016] [Accepted: 11/29/2016] [Indexed: 01/22/2023] Open
Abstract
Recent microscopic and simulation studies have shown that the genome structure fluctuates dynamically in the nuclei of budding yeast Saccharomyces cerevisiae. This genome-wide movement should lead to the fluctuations of individual genes in their territorial regions. This raises an intriguing question of whether the resulting distribution of genes is correlated to their transcriptional activity. An effective method for examining this correlation is to analyze how the spatial distribution of genes and their transcriptional activity are modified by mutation. In this study, we analyzed the modification observed in a budding yeast mutant in which genes necessary for anchoring telomeres to the nuclear envelope, yku70 and esc1, are silenced. Taddei et al. reported that 60 genes are clearly misregulated by this mutation, with 28 and 32 genes downregulated and upregulated, respectively. We calculated the probability density maps of the misregulated genes using a model of dynamical movement of the yeast genome in both wild-type (WT) and yku70 esc1 mutant and showed that the density of downregulated genes is larger near the nucleolus, whereas the density of upregulated genes is larger at the opposite side of the nucleus. By comparing these genes with those highly (top 200 of transcriptome) and lowly (bottom 200) expressed, we showed that the simulated distribution of 28 downregulated (12 out of 32 upregulated) genes has a distinctly larger overlap with the distribution of lowly (highly) expressed genes in the mutant than in the WT. The remaining 20 upregulated genes are localized near the nuclear envelope both in the WT and in the mutant. These results showed that the transcriptional level of genes is affected by their spatial distribution, thus highlighting the importance of the structural regulation in the yeast genome.
Collapse
Affiliation(s)
- Naoko Tokuda
- Department of Computational Science and Engineering, Nagoya University, Nagoya, Japan
| | - Masaki Sasai
- Department of Computational Science and Engineering, Nagoya University, Nagoya, Japan; Department of Applied Physics, Nagoya University, Nagoya, Japan.
| |
Collapse
|
45
|
Abstract
Chromosomes are folded into cells in a nonrandom fashion, with particular genetic loci occupying distinct spatial regions. This observation raises the question of whether the spatial organization of a chromosome governs its functions, such as recombination or transcription. We consider this general question in the specific context of mating-type switching in budding yeast, which is a model system for homologous recombination. Mating-type switching is induced by a DNA double-strand break (DSB) at the MAT locus on chromosome III, followed by homologous recombination between the cut MAT locus and one of two donor loci (HMLα and HMRa), located on the same chromosome. Previous studies have suggested that in MATa cells after the DSB is induced chromosome III undergoes refolding, which directs the MAT locus to recombine with HMLα. Here, we propose a quantitative model of mating-type switching predicated on the assumption of DSB-induced chromosome refolding, which also takes into account the previously measured stochastic dynamics and polymer nature of yeast chromosomes. Using quantitative fluorescence microscopy, we measure changes in the distance between the donor (HMLα) and MAT loci after the DSB and find agreement with the theory. Predictions of the theory also agree with measurements of changes in the use of HMLα as the donor, when we perturb the refolding of chromosome III. These results establish refolding of yeast chromosome III as a key driving force in MAT switching and provide an example of a cell regulating the spatial organization of its chromosome so as to direct homology search during recombination.
Collapse
|
46
|
Kuznetsova MA, Sheval EV. Chromatin fibers: from classical descriptions to modern interpretation. Cell Biol Int 2016; 40:1140-1151. [PMID: 27569720 DOI: 10.1002/cbin.10672] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 08/20/2016] [Indexed: 12/14/2022]
Abstract
The first description of intrachromosomal fibers was made by Baranetzky in 1880. Since that time, a plethora of fibrillar substructures have been described inside the mitotic chromosomes, and published data indicate that chromosomes may be formed as a result of the hierarchical folding of chromatin fibers. In this review, we examine the evolution and the current state of research on the morphological organization of mitotic chromosomes.
Collapse
Affiliation(s)
- Maria A Kuznetsova
- Faculty of Bioengineering and Bioinformatics, M.V. Lomonosov Moscow State University, 119992, Moscow, Russia.,A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119992, Moscow, Russia
| | - Eugene V Sheval
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119992, Moscow, Russia. .,LIA1066 French-Russian Joint Cancer Research Laboratory, 119334, Moscow, Russia.
| |
Collapse
|
47
|
Chen C, Lim HH, Shi J, Tamura S, Maeshima K, Surana U, Gan L. Budding yeast chromatin is dispersed in a crowded nucleoplasm in vivo. Mol Biol Cell 2016; 27:3357-3368. [PMID: 27605704 PMCID: PMC5170867 DOI: 10.1091/mbc.e16-07-0506] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/01/2016] [Indexed: 11/11/2022] Open
Abstract
Chromatin organization has an important role in the regulation of eukaryotic systems. Although recent studies have refined the three-dimensional models of chromatin organization with high resolution at the genome sequence level, little is known about how the most fundamental units of chromatin-nucleosomes-are positioned in three dimensions in vivo. Here we use electron cryotomography to study chromatin organization in the budding yeast Saccharomyces cerevisiae Direct visualization of yeast nuclear densities shows no evidence of 30-nm fibers. Aside from preribosomes and spindle microtubules, few nuclear structures are larger than a tetranucleosome. Yeast chromatin does not form compact structures in interphase or mitosis and is consistent with being in an "open" configuration that is conducive to high levels of transcription. From our study and those of others, we propose that yeast can regulate its transcription using local nucleosome-nucleosome associations.
Collapse
Affiliation(s)
- Chen Chen
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Hong Hwa Lim
- Institute of Molecular and Cell Biology, Agency for Science Technology and Research, Proteos, Singapore 138673, Singapore.,Bioprocessing Technology Institute, Singapore 138668, Singapore
| | - Jian Shi
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Sachiko Tamura
- National Institute of Genetics and Sokendai, Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan
| | - Kazuhiro Maeshima
- National Institute of Genetics and Sokendai, Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan
| | - Uttam Surana
- Institute of Molecular and Cell Biology, Agency for Science Technology and Research, Proteos, Singapore 138673, Singapore.,Bioprocessing Technology Institute, Singapore 138668, Singapore.,Department of Pharmacology, National University of Singapore, Singapore 117543, Singapore
| | - Lu Gan
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore
| |
Collapse
|
48
|
Zhan Y, Giorgetti L, Tiana G. Looping probability of random heteropolymers helps to understand the scaling properties of biopolymers. Phys Rev E 2016; 94:032402. [PMID: 27739813 DOI: 10.1103/physreve.94.032402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 06/06/2023]
Abstract
Random heteropolymers are a minimal description of biopolymers and can provide a theoretical framework to the investigate the formation of loops in biophysical experiments. The looping probability as a function of polymer length was observed to display in some biopolymers, like chromosomes in cell nuclei or long RNA chains, anomalous scaling exponents. Combining a two-state model with self-adjusting simulated-tempering calculations, we calculate numerically the looping properties of several realizations of the random interactions within the chain. We find a continuous set of exponents upon varying the temperature, which arises from finite-size effects and is amplified by the disorder of the interactions. We suggest that this could provide a simple explanation for the anomalous scaling exponents found in experiments. In addition, our results have important implications notably for the study of chromosome folding as they show that scaling exponents cannot be the sole criteria for testing hypothesis-driven models of chromosome architecture.
Collapse
Affiliation(s)
- Y Zhan
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | - L Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | - G Tiana
- Center for Complexity and Biosystems and Department of Physics, Università degli Studi di Milano and INFN, via Celoria 16, 20133 Milano, Italy
| |
Collapse
|
49
|
Pueschel R, Coraggio F, Meister P. From single genes to entire genomes: the search for a function of nuclear organization. Development 2016; 143:910-23. [PMID: 26980791 DOI: 10.1242/dev.129007] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The existence of different domains within the nucleus has been clear from the time, in the late 1920s, that heterochromatin and euchromatin were discovered. The observation that heterochromatin is less transcribed than euchromatin suggested that microscopically identifiable structures might correspond to functionally different domains of the nucleus. Until 15 years ago, studies linking gene expression and subnuclear localization were limited to a few genes. As we discuss in this Review, new genome-wide techniques have now radically changed the way nuclear organization is analyzed. These have provided a much more detailed view of functional nuclear architecture, leading to the emergence of a number of new paradigms of chromatin folding and how this folding evolves during development.
Collapse
Affiliation(s)
- Ringo Pueschel
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland Graduate School for Cellular and Biomedical Sciences, University of Bern, Switzerland
| | - Francesca Coraggio
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland Graduate School for Cellular and Biomedical Sciences, University of Bern, Switzerland
| | - Peter Meister
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
| |
Collapse
|
50
|
Vasquez PA, Hult C, Adalsteinsson D, Lawrimore J, Forest MG, Bloom K. Entropy gives rise to topologically associating domains. Nucleic Acids Res 2016; 44:5540-9. [PMID: 27257057 PMCID: PMC4937343 DOI: 10.1093/nar/gkw510] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 05/06/2016] [Accepted: 05/25/2016] [Indexed: 12/15/2022] Open
Abstract
We investigate chromosome organization within the nucleus using polymer models whose formulation is closely guided by experiments in live yeast cells. We employ bead-spring chromosome models together with loop formation within the chains and the presence of nuclear bodies to quantify the extent to which these mechanisms shape the topological landscape in the interphase nucleus. By investigating the genome as a dynamical system, we show that domains of high chromosomal interactions can arise solely from the polymeric nature of the chromosome arms due to entropic interactions and nuclear confinement. In this view, the role of bio-chemical related processes is to modulate and extend the duration of the interacting domains.
Collapse
Affiliation(s)
- Paula A Vasquez
- Department of Mathematics, University of South Carolina, Columbia, SC 29808, USA
| | - Caitlin Hult
- Department of Mathematics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - David Adalsteinsson
- Department of Mathematics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Josh Lawrimore
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Mark G Forest
- Department of Mathematics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kerry Bloom
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| |
Collapse
|