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Sala A, Labrador M, Buitrago D, De Jorge P, Battistini F, Heath I, Orozco M. An integrated machine-learning model to predict nucleosome architecture. Nucleic Acids Res 2024; 52:10132-10143. [PMID: 39162225 PMCID: PMC11417389 DOI: 10.1093/nar/gkae689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 07/17/2024] [Accepted: 07/29/2024] [Indexed: 08/21/2024] Open
Abstract
We demonstrate that nucleosomes placed in the gene body can be accurately located from signal decay theory assuming two emitters located at the beginning and at the end of genes. These generated wave signals can be in phase (leading to well defined nucleosome arrays) or in antiphase (leading to fuzzy nucleosome architectures). We found that the first (+1) and the last (-last) nucleosomes are contiguous to regions signaled by transcription factor binding sites and unusual DNA physical properties that hinder nucleosome wrapping. Based on these analyses, we developed a method that combines Machine Learning and signal transmission theory able to predict the basal locations of the nucleosomes with an accuracy similar to that of experimental MNase-seq based methods.
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Affiliation(s)
- Alba Sala
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Mireia Labrador
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Diana Buitrago
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Pau De Jorge
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Federica Battistini
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Departament de Bioquímica i Biomedicina, Universitat de Barcelona, Barcelona, Spain
| | - Isabelle Brun Heath
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Departament de Bioquímica i Biomedicina, Universitat de Barcelona, Barcelona, Spain
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2
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Zeitler L, André K, Alberti A, Denby Wilkes C, Soutourina J, Goldar A. A genome-wide comprehensive analysis of nucleosome positioning in yeast. PLoS Comput Biol 2024; 20:e1011799. [PMID: 38266035 PMCID: PMC10843174 DOI: 10.1371/journal.pcbi.1011799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 02/05/2024] [Accepted: 01/03/2024] [Indexed: 01/26/2024] Open
Abstract
In eukaryotic cells, the one-dimensional DNA molecules need to be tightly packaged into the spatially constraining nucleus. Folding is achieved on its lowest level by wrapping the DNA around nucleosomes. Their arrangement regulates other nuclear processes, such as transcription and DNA repair. Despite strong efforts to study nucleosome positioning using Next Generation Sequencing (NGS) data, the mechanism of their collective arrangement along the gene body remains poorly understood. Here, we classify nucleosome distributions of protein-coding genes in Saccharomyces cerevisiae according to their profile similarity and analyse their differences using functional Principal Component Analysis. By decomposing the NGS signals into their main descriptive functions, we compared wild type and chromatin remodeler-deficient strains, keeping position-specific details preserved whilst considering the nucleosome arrangement as a whole. A correlation analysis with other genomic properties, such as gene size and length of the upstream Nucleosome Depleted Region (NDR), identified key factors that influence the nucleosome distribution. We reveal that the RSC chromatin remodeler-which is responsible for NDR maintenance-is indispensable for decoupling nucleosome arrangement within the gene from positioning outside, which interfere in rsc8-depleted conditions. Moreover, nucleosome profiles in chd1Δ strains displayed a clear correlation with RNA polymerase II presence, whereas wild type cells did not indicate a noticeable interdependence. We propose that RSC is pivotal for global nucleosome organisation, whilst Chd1 plays a key role for maintaining local arrangement.
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Affiliation(s)
- Leo Zeitler
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC),Gif-sur-Yvette, France
| | - Kévin André
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC),Gif-sur-Yvette, France
| | - Adriana Alberti
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC),Gif-sur-Yvette, France
| | - Cyril Denby Wilkes
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC),Gif-sur-Yvette, France
| | - Julie Soutourina
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC),Gif-sur-Yvette, France
| | - Arach Goldar
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC),Gif-sur-Yvette, France
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3
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Proestou DA, Sullivan ME, Lundgren KM, Ben-Horin T, Witkop EM, Hart KM. Understanding Crassostrea virginica tolerance of Perkinsus marinus through global gene expression analysis. Front Genet 2023; 14:1054558. [PMID: 36741318 PMCID: PMC9892467 DOI: 10.3389/fgene.2023.1054558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 01/09/2023] [Indexed: 01/20/2023] Open
Abstract
Disease tolerance, a host's ability to limit damage from a given parasite burden, is quantified by the relationship between pathogen load and host survival or reproduction. Dermo disease, caused by the protozoan parasite P. marinus, negatively impacts survival in both wild and cultured eastern oyster (C. virginica) populations. Resistance to P. marinus has been the focus of previous studies, but tolerance also has important consequences for disease management in cultured and wild populations. In this study we measured dermo tolerance and evaluated global expression patterns of two sensitive and two tolerant eastern oyster families experimentally challenged with distinct doses of P. marinus (0, 106, 107, and 108 parasite spores per gram wet weight, n = 3-5 individuals per family per dose). Weighted Gene Correlation Network Analysis (WGCNA) identified several modules correlated with increasing parasite dose/infection intensity, as well as phenotype. Modules positively correlated with dose included transcripts and enriched GO terms related to hemocyte activation and cell cycle activity. Additionally, these modules included G-protein coupled receptor, toll-like receptor, and tumor necrosis factor pathways, which are important for immune effector molecule and apoptosis activation. Increased metabolic activity was also positively correlated with treatment. The module negatively correlated with infection intensity was enriched with GO terms associated with normal cellular activity and growth, indicating a trade-off with increased immune response. The module positively correlated with the tolerant phenotype was enriched for transcripts associated with "programmed cell death" and contained a large number of tripartite motif-containing proteins. Differential expression analysis was also performed on the 108 dosed group using the most sensitive family as the comparison reference. Results were consistent with the network analysis, but signals for "programmed cell death" and serine protease inhibitors were stronger in one tolerant family than the other, suggesting that there are multiple avenues for disease tolerance. These results provide new insight for defining dermo response traits and have important implications for applying selective breeding for disease management.
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Affiliation(s)
- Dina A. Proestou
- National Cold Water Marine Aquaculture Center, USDA Agricultural Research Service, Kingston, RI, United States
| | - Mary E. Sullivan
- National Cold Water Marine Aquaculture Center, USDA Agricultural Research Service, Kingston, RI, United States
| | - Kathryn Markey Lundgren
- National Cold Water Marine Aquaculture Center, USDA Agricultural Research Service, Kingston, RI, United States
| | - Tal Ben-Horin
- Department of Fisheries, Animal and Veterinary Science, University of Rhode Island, Kingston, RI, United States
| | - Erin M. Witkop
- Department of Fisheries, Animal and Veterinary Science, University of Rhode Island, Kingston, RI, United States
| | - Keegan M. Hart
- National Cold Water Marine Aquaculture Center, USDA Agricultural Research Service, Kingston, RI, United States
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4
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Barissi S, Sala A, Wieczór M, Battistini F, Orozco M. DNAffinity: a machine-learning approach to predict DNA binding affinities of transcription factors. Nucleic Acids Res 2022; 50:9105-9114. [PMID: 36018808 PMCID: PMC9458447 DOI: 10.1093/nar/gkac708] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 07/21/2022] [Accepted: 08/08/2022] [Indexed: 12/24/2022] Open
Abstract
We present a physics-based machine learning approach to predict in vitro transcription factor binding affinities from structural and mechanical DNA properties directly derived from atomistic molecular dynamics simulations. The method is able to predict affinities obtained with techniques as different as uPBM, gcPBM and HT-SELEX with an excellent performance, much better than existing algorithms. Due to its nature, the method can be extended to epigenetic variants, mismatches, mutations, or any non-coding nucleobases. When complemented with chromatin structure information, our in vitro trained method provides also good estimates of in vivo binding sites in yeast.
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Affiliation(s)
| | | | - Miłosz Wieczór
- Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology. Baldiri Reixac 10–12, 08028 Barcelona, Spain,Department of Physical Chemistry. Gdansk University of Technology, 80-233 Gdańsk, Poland
| | | | - Modesto Orozco
- Correspondence may also be addressed to Modesto Orozco. Tel: +34 934 037 156;
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5
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Aberrant nucleosome organization in mouse SCNT embryos revealed by ULI-MNase-seq. Stem Cell Reports 2022; 17:1730-1742. [PMID: 35750045 PMCID: PMC9287678 DOI: 10.1016/j.stemcr.2022.05.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/25/2022] [Accepted: 05/26/2022] [Indexed: 11/23/2022] Open
Abstract
Somatic cell nuclear transfer (SCNT) can reprogram terminally differentiated somatic cells into totipotent embryos, but with multiple defects. The nucleosome positioning, as an important epigenetic regulator for gene expression, is largely unexplored during SCNT embryonic development. Here, we mapped genome-wide nucleosome profiles in mouse SCNT embryos using ultra-low-input MNase-seq (ULI-MNase-seq). We found that the nucleosome-depleted regions (NDRs) around promoters underwent dramatic reestablishment, which is consistent with the cell cycle. Dynamics of nucleosome position in SCNT embryos were delayed compared to fertilized embryos. Subsequently, we found that the aberrant gene expression levels in inner cell mass (ICM) were positively correlated with promoter NDRs in donor cells, which indicated that the memory of nucleosome occupancy in donor cells was a potential barrier for SCNT-mediated reprogramming. We further confirmed that the histone acetylation level of donor cells was associated with the memory of promoter NDRs. Our study provides insight into nucleosome reconfiguration during SCNT preimplantation embryonic development.
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Singh AK, Schauer T, Pfaller L, Straub T, Mueller-Planitz F. The biogenesis and function of nucleosome arrays. Nat Commun 2021; 12:7011. [PMID: 34853297 PMCID: PMC8636622 DOI: 10.1038/s41467-021-27285-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 11/09/2021] [Indexed: 11/24/2022] Open
Abstract
Numerous chromatin remodeling enzymes position nucleosomes in eukaryotic cells. Aside from these factors, transcription, DNA sequence, and statistical positioning of nucleosomes also shape the nucleosome landscape. The precise contributions of these processes remain unclear due to their functional redundancy in vivo. By incisive genome engineering, we radically decreased their redundancy in Saccharomyces cerevisiae. The transcriptional machinery strongly disrupts evenly spaced nucleosomes. Proper nucleosome density and DNA sequence are critical for their biogenesis. The INO80 remodeling complex helps space nucleosomes in vivo and positions the first nucleosome over genes in an H2A.Z-independent fashion. INO80 requires its Arp8 subunit but unexpectedly not the Nhp10 module for spacing. Cells with irregularly spaced nucleosomes suffer from genotoxic stress including DNA damage, recombination and transpositions. We derive a model of the biogenesis of the nucleosome landscape and suggest that it evolved not only to regulate but also to protect the genome.
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Affiliation(s)
- Ashish Kumar Singh
- grid.5252.00000 0004 1936 973XMolecular Biology, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, München, Germany
| | - Tamás Schauer
- grid.5252.00000 0004 1936 973XBioinformatics Unit, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, München, Germany
| | - Lena Pfaller
- grid.5252.00000 0004 1936 973XMolecular Biology, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, München, Germany ,grid.419481.10000 0001 1515 9979Present Address: Novartis Institutes for BioMedical Research, 4056 Basel, Switzerland
| | - Tobias Straub
- grid.5252.00000 0004 1936 973XBioinformatics Unit, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, München, Germany
| | - Felix Mueller-Planitz
- Molecular Biology, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, München, Germany. .,Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307, Dresden, Germany.
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7
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Lima ARJ, de Araujo CB, Bispo S, Patané J, Silber AM, Elias MC, da Cunha JPC. Nucleosome landscape reflects phenotypic differences in Trypanosoma cruzi life forms. PLoS Pathog 2021; 17:e1009272. [PMID: 33497423 PMCID: PMC7864430 DOI: 10.1371/journal.ppat.1009272] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 02/05/2021] [Accepted: 01/04/2021] [Indexed: 11/25/2022] Open
Abstract
Trypanosoma cruzi alternates between replicative and nonreplicative life forms, accompanied by a shift in global transcription levels and by changes in the nuclear architecture, the chromatin proteome and histone posttranslational modifications. To gain further insights into the epigenetic regulation that accompanies life form changes, we performed genome-wide high-resolution nucleosome mapping using two T. cruzi life forms (epimastigotes and cellular trypomastigotes). By combining a powerful pipeline that allowed us to faithfully compare nucleosome positioning and occupancy, more than 125 thousand nucleosomes were mapped, and approximately 20% of them differed between replicative and nonreplicative forms. The nonreplicative forms have less dynamic nucleosomes, possibly reflecting their lower global transcription levels and DNA replication arrest. However, dynamic nucleosomes are enriched at nonreplicative regulatory transcription initiation regions and at multigenic family members, which are associated with infective-stage and virulence factors. Strikingly, dynamic nucleosome regions are associated with GO terms related to nuclear division, translation, gene regulation and metabolism and, notably, associated with transcripts with different expression levels among life forms. Finally, the nucleosome landscape reflects the steady-state transcription expression: more abundant genes have a more deeply nucleosome-depleted region at putative 5' splice sites, likely associated with trans-splicing efficiency. Taken together, our results indicate that chromatin architecture, defined primarily by nucleosome positioning and occupancy, reflects the phenotypic differences found among T. cruzi life forms despite the lack of a canonical transcriptional control context.
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Affiliation(s)
- Alex R. J. Lima
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Christiane B. de Araujo
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Saloe Bispo
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - José Patané
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Ariel M. Silber
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, Universidade de São Paulo, São Paulo, Brazil
| | - M. Carolina Elias
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
- * E-mail: (MCE); (JPCC)
| | - Julia P. C. da Cunha
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
- * E-mail: (MCE); (JPCC)
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8
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Maji A, Padinhateeri R, Mitra MK. The Accidental Ally: Nucleosome Barriers Can Accelerate Cohesin-Mediated Loop Formation in Chromatin. Biophys J 2020; 119:2316-2325. [PMID: 33181117 PMCID: PMC7732762 DOI: 10.1016/j.bpj.2020.10.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/21/2020] [Accepted: 10/13/2020] [Indexed: 01/26/2023] Open
Abstract
An important question in the context of the three-dimensional organization of chromosomes is the mechanism of formation of large loops between distant basepairs. Recent experiments suggest that the formation of loops might be mediated by loop extrusion factor proteins such as cohesin. Experiments on cohesin have shown that cohesins walk diffusively on the DNA and that nucleosomes act as obstacles to the diffusion, lowering the permeability and hence reducing the effective diffusion constant. An estimation of the times required to form the loops of typical sizes seen in Hi-C experiments using these low-effective-diffusion constants leads to times that are unphysically large. The puzzle then is the following: how does a cohesin molecule diffusing on the DNA backbone achieve speeds necessary to form the large loops seen in experiments? We propose a simple answer to this puzzle and show that although at low densities, nucleosomes act as barriers to cohesin diffusion, beyond a certain concentration they can reduce loop formation times because of a subtle interplay between the nucleosome size and the mean linker length. This effect is further enhanced on considering stochastic binding kinetics of nucleosomes on the DNA backbone and leads to predictions of lower loop formation times than might be expected from a naive obstacle picture of nucleosomes.
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Affiliation(s)
- Ajoy Maji
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Mithun K Mitra
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India.
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9
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Portillo-Ledesma S, Tsao LH, Wagley M, Lakadamyali M, Cosma MP, Schlick T. Nucleosome Clutches are Regulated by Chromatin Internal Parameters. J Mol Biol 2020; 433:166701. [PMID: 33181171 DOI: 10.1016/j.jmb.2020.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/27/2020] [Accepted: 11/02/2020] [Indexed: 01/17/2023]
Abstract
Nucleosomes cluster together when chromatin folds in the cell to form heterogeneous groups termed "clutches". These structural units add another level of chromatin regulation, for example during cell differentiation. Yet, the mechanisms that regulate their size and compaction remain obscure. Here, using our chromatin mesoscale model, we dissect clutch patterns in fibers with different combinations of nucleosome positions, linker histone density, and acetylation levels to investigate their role in clutch regulation. First, we isolate the effect of each chromatin parameter by studying systems with regular nucleosome spacing; second, we design systems with naturally-occurring linker lengths that fold onto specific clutch patterns; third, we model gene-encoding fibers to understand how these combined factors contribute to gene structure. Our results show how these chromatin parameters act together to produce different-sized nucleosome clutches. The length of nucleosome free regions (NFRs) profoundly affects clutch size, while the length of linker DNA has a moderate effect. In general, higher linker histone densities produce larger clutches by a chromatin compaction mechanism, while higher acetylation levels produce smaller clutches by a chromatin unfolding mechanism. We also show that it is possible to design fibers with naturally-occurring DNA linkers and NFRs that fold onto specific clutch patterns. Finally, in gene-encoding systems, a complex combination of variables dictates a gene-specific clutch pattern. Together, these results shed light into the mechanisms that regulate nucleosome clutches and suggest a new epigenetic mechanism by which chromatin parameters regulate transcriptional activity via the three-dimensional folded state of the genome at a nucleosome level.
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Affiliation(s)
- Stephanie Portillo-Ledesma
- Department of Chemistry, New York University, 1021 Silver, 100 Washington Square East, New York, NY, 10003, USA
| | - Lucille H Tsao
- Department of Chemistry, New York University, 1021 Silver, 100 Washington Square East, New York, NY, 10003, USA
| | - Meghna Wagley
- Department of Chemistry, New York University, 1021 Silver, 100 Washington Square East, New York, NY, 10003, USA
| | - Melike Lakadamyali
- Perelman School of Medicine, Department of Physiology, University of Pennsylvania, Clinical Research Building, 415 Curie Boulevard, Philadelphia, PA 19104, USA; Perelman School of Medicine, Department of Cell and Developmental Biology, University of Pennsylvania, Clinical Research Building, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Maria Pia Cosma
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Dr Aiguader 88, 08003 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, 08010 Barcelona, Spain; Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou 510005, China; CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Tamar Schlick
- Department of Chemistry, New York University, 1021 Silver, 100 Washington Square East, New York, NY, 10003, USA; New York University-East China Normal University Center for Computational Chemistry at New York University Shanghai, Room 340, Geography Building, 3663 North Zhongshan Road, Shanghai, 200062, China; Courant Institute of Mathematical Sciences, New York University, 251 Mercer St, New York, NY, 10012, USA.
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10
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Sural S, Liang CY, Wang FY, Ching TT, Hsu AL. HSB-1/HSF-1 pathway modulates histone H4 in mitochondria to control mtDNA transcription and longevity. SCIENCE ADVANCES 2020; 6:eaaz4452. [PMID: 33087356 PMCID: PMC7577724 DOI: 10.1126/sciadv.aaz4452] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 09/08/2020] [Indexed: 06/02/2023]
Abstract
Heat shock factor-1 (HSF-1) is a master regulator of stress responses across taxa. Overexpression of HSF-1 or genetic ablation of its conserved negative regulator, heat shock factor binding protein 1 (HSB-1), results in robust life-span extension in Caenorhabditis elegans Here, we found that increased HSF-1 activity elevates histone H4 levels in somatic tissues during development, while knockdown of H4 completely suppresses HSF-1-mediated longevity. Moreover, overexpression of H4 is sufficient to extend life span. Ablation of HSB-1 induces an H4-dependent increase in micrococcal nuclease protection of both nuclear chromatin and mitochondrial DNA (mtDNA), which consequently results in reduced transcription of mtDNA-encoded complex IV genes, decreased respiratory capacity, and a mitochondrial unfolded protein response-dependent life-span extension. Collectively, our findings reveal a previously unknown role of HSB-1/HSF-1 signaling in modulation of mitochondrial function via mediating histone H4-dependent regulation of mtDNA gene expression and concomitantly acting as a determinant of organismal longevity.
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Affiliation(s)
- Surojit Sural
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Chung-Yi Liang
- Research Center for Healthy Aging, China Medical University, Taichung, 404, Taiwan
| | - Feng-Yung Wang
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan
| | - Tsui-Ting Ching
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei 112, Taiwan.
| | - Ao-Lin Hsu
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
- Research Center for Healthy Aging, China Medical University, Taichung, 404, Taiwan
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan
- Division of Geriatric and Palliative Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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11
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Epigenetic Mechanisms Contribute to Evolutionary Adaptation of Gene Network Activity under Environmental Selection. Cell Rep 2020; 33:108306. [PMID: 33113358 PMCID: PMC7656290 DOI: 10.1016/j.celrep.2020.108306] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/17/2019] [Accepted: 10/02/2020] [Indexed: 11/30/2022] Open
Abstract
How evolution can be facilitated by epigenetic mechanisms has received refreshed attention recently. To explore the role epigenetic inheritance plays in evolution, we subject isogenic wild-type yeast cells expressing PGAL1-YFP (yellow fluorescent protein) to selection by daily sorting based on reporter expression. We observe expression-level reductions in multiple replicates sorted for the lowest expression that persist for several days, even after lifting the selection pressure. Reduced expression is due to factors in the galactose (GAL) network rather than global factors. Results using a constitutively active GAL network are in overall agreement with findings with the wild-type network. We find that the local chromatin environment of the reporter has a significant effect on the observed phenotype. Genome sequencing, chromatin immunoprecipitation (ChIP)-qPCR, and sporulation analysis provide further insights into the epigenetic and genetic contributors to the expression changes observed. Our work provides a comprehensive example of the role played by epigenetic mechanisms on gene network evolution. Luo et al. demonstrate how epigenetic mechanisms contribute to the evolution of gene network activity. Subjecting yeast cells to repeated environmental selection based on the activity of the galactose network, they observe sustained changes in reporter expression level. They characterize the epigenetic and genetic factors contributing to the observed phenotypes.
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12
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Buitrago D, Codó L, Illa R, de Jorge P, Battistini F, Flores O, Bayarri G, Royo R, Del Pino M, Heath S, Hospital A, Gelpí JL, Heath IB, Orozco M. Nucleosome Dynamics: a new tool for the dynamic analysis of nucleosome positioning. Nucleic Acids Res 2019; 47:9511-9523. [PMID: 31504766 PMCID: PMC6765203 DOI: 10.1093/nar/gkz759] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/23/2019] [Accepted: 08/22/2019] [Indexed: 02/03/2023] Open
Abstract
We present Nucleosome Dynamics, a suite of programs integrated into a virtual research environment and created to define nucleosome architecture and dynamics from noisy experimental data. The package allows both the definition of nucleosome architectures and the detection of changes in nucleosomal organization due to changes in cellular conditions. Results are displayed in the context of genomic information thanks to different visualizers and browsers, allowing the user a holistic, multidimensional view of the genome/transcriptome. The package shows good performance for both locating equilibrium nucleosome architecture and nucleosome dynamics and provides abundant useful information in several test cases, where experimental data on nucleosome position (and for some cases expression level) have been collected for cells under different external conditions (cell cycle phase, yeast metabolic cycle progression, changes in nutrients or difference in MNase digestion level). Nucleosome Dynamics is a free software and is provided under several distribution models.
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Affiliation(s)
- Diana Buitrago
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Laia Codó
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain
| | - Ricard Illa
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Pau de Jorge
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Federica Battistini
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Oscar Flores
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Genis Bayarri
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Romina Royo
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain
| | - Marc Del Pino
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain
| | - Simon Heath
- Centro Nacional de Análisis Genómico (CNAG-CRG), Centre de Regulacio Genómico (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Adam Hospital
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Josep Lluís Gelpí
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain.,Departament de Bioquímica i Biomedicina. Facultat de Biologia, Universitat de Barcelona, Avgda Diagonal 647, Barcelona 08028, Spain
| | - Isabelle Brun Heath
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain.,Departament de Bioquímica i Biomedicina. Facultat de Biologia, Universitat de Barcelona, Avgda Diagonal 647, Barcelona 08028, Spain
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13
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Chanda PK, Meng S, Lee J, Leung HE, Chen K, Cooke JP. Nuclear S-Nitrosylation Defines an Optimal Zone for Inducing Pluripotency. Circulation 2019; 140:1081-1099. [PMID: 31412725 DOI: 10.1161/circulationaha.119.042371] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND We found that cell-autonomous innate immune signaling causes global changes in the expression of epigenetic modifiers to facilitate nuclear reprogramming to pluripotency. A role of S-nitrosylation by inducible nitric oxide (NO) synthase, an important effector of innate immunity, has been previously described in the transdifferentiation of fibroblasts to endothelial cells. Accordingly, we hypothesized that S-nitrosylation might also have a role in nuclear reprogramming to pluripotency. METHODS We used murine embryonic fibroblasts containing a doxycycline-inducible cassette encoding the Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc), and genetic or pharmacological inhibition of inducible NO synthase together with the Tandem Mass Tag approach, chromatin immunoprecipitation-quantitative polymerase chain reaction, site-directed mutagenesis, and micrococcal nuclease assay to determine the role of S-nitrosylation during nuclear reprogramming to pluripotency. RESULTS We show that an optimal zone of innate immune activation, as defined by maximal yield of induced pluripotent stem cells, is determined by the degree of activation of nuclear factor κ-light-chain-enhancer of activated B cells; NO generation; S-nitrosylation of nuclear proteins; and DNA accessibility as reflected by histone markings and increased mononucleosome generation in a micrococcal nuclease assay. Genetic or pharmacological inhibition of inducible NO synthase reduces DNA accessibility and suppresses induced pluripotent stem cell generation. The effect of NO on DNA accessibility is mediated in part by S-nitrosylation of nuclear proteins, including MTA3 (Metastasis Associated 1 Family Member 3), a subunit of NuRD (Nucleosome Remodeling Deacetylase) complex. S-Nitrosylation of MTA3 is associated with decreased NuRD activity. Overexpression of mutant MTA3, in which the 2 cysteine residues are replaced by alanine residues, impairs the generation of induced pluripotent stem cells. CONCLUSIONS This is the first report showing that DNA accessibility and induced pluripotent stem cell yield depend on the extent of cell-autonomous innate immune activation and NO generation. This "Goldilocks zone" for inflammatory signaling and epigenetic plasticity may have broader implications for cell fate and phenotypic fluidity.
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Affiliation(s)
- Palas K Chanda
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, TX (P.K.C., S.M., K.C., J.P.C.)
| | - Shu Meng
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, TX (P.K.C., S.M., K.C., J.P.C.)
| | - Jieun Lee
- AgeX Therapeutics Inc, Alameda, CA (J.L.)
| | - Honchiu E Leung
- Department of Medicine, Baylor College of Medicine, Houston, TX (H.E.L.)
| | - Kaifu Chen
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, TX (P.K.C., S.M., K.C., J.P.C.)
| | - John P Cooke
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, TX (P.K.C., S.M., K.C., J.P.C.)
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14
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Foss EJ, Gatbonton-Schwager T, Thiesen AH, Taylor E, Soriano R, Lao U, MacAlpine DM, Bedalov A. Sir2 suppresses transcription-mediated displacement of Mcm2-7 replicative helicases at the ribosomal DNA repeats. PLoS Genet 2019; 15:e1008138. [PMID: 31083663 PMCID: PMC6532929 DOI: 10.1371/journal.pgen.1008138] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/23/2019] [Accepted: 04/15/2019] [Indexed: 11/23/2022] Open
Abstract
Repetitive DNA sequences within eukaryotic heterochromatin are poorly transcribed and replicate late in S-phase. In Saccharomyces cerevisiae, the histone deacetylase Sir2 is required for both transcriptional silencing and late replication at the repetitive ribosomal DNA arrays (rDNA). Despite the widespread association between transcription and replication timing, it remains unclear how transcription might impinge on replication, or vice versa. Here we show that, when silencing of an RNA polymerase II (RNA Pol II)-transcribed non-coding RNA at the rDNA is disrupted by SIR2 deletion, RNA polymerase pushes and thereby relocalizes replicative Mcm2-7 helicases away from their loading sites to an adjacent region with low nucleosome occupancy, and this relocalization is associated with increased rDNA origin efficiency. Our results suggest a model in which two of the major defining features of heterochromatin, transcriptional silencing and late replication, are mechanistically linked through suppression of polymerase-mediated displacement of replication initiation complexes. Eukaryotic genomes typically contain large regions of repetitive DNA, referred to as heterochromatin, that are both transcriptionally silent and late replicating. We provide a possible explanation for the association between transcriptional silencing and late replication. Budding yeast contains a histone deacetylase called SIR2 that was originally identified as a transcriptional repressor, but was later also found to ensure late replication of repetitive ribosomal DNA (rDNA) sequences. We show that the transcription that occurs in the absence of SIR2 directly displaces the helicase required for replication initiation at the rDNA. This work represents an important advance in understanding the interplay between transcription and replication at repetitive sequences by directly linking transcription with replication machinery in heterochromatin.
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Affiliation(s)
- Eric J Foss
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | | | - Adam H Thiesen
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Erin Taylor
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Rafael Soriano
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Uyen Lao
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - David M MacAlpine
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, United States of America
| | - Antonio Bedalov
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America.,Department of Medicine, University of Washington, Seattle, WA, United States of America.,Department of Biochemistry, University of Washington, Seattle, WA, United States of America
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15
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Dronamraju R, Hepperla AJ, Shibata Y, Adams AT, Magnuson T, Davis IJ, Strahl BD. Spt6 Association with RNA Polymerase II Directs mRNA Turnover During Transcription. Mol Cell 2019; 70:1054-1066.e4. [PMID: 29932900 DOI: 10.1016/j.molcel.2018.05.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/23/2018] [Accepted: 05/17/2018] [Indexed: 10/28/2022]
Abstract
Spt6 is an essential histone chaperone that mediates nucleosome reassembly during gene transcription. Spt6 also associates with RNA polymerase II (RNAPII) via a tandem Src2 homology domain. However, the significance of Spt6-RNAPII interaction is not well understood. Here, we show that Spt6 recruitment to genes and the nucleosome reassembly functions of Spt6 can still occur in the absence of its association with RNAPII. Surprisingly, we found that Spt6-RNAPII association is required for efficient recruitment of the Ccr4-Not de-adenylation complex to transcribed genes for essential degradation of a range of mRNAs, including mRNAs required for cell-cycle progression. These findings reveal an unexpected control mechanism for mRNA turnover during transcription facilitated by a histone chaperone.
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Affiliation(s)
- Raghuvar Dronamraju
- Department of Biochemistry & Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Austin J Hepperla
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yoichiro Shibata
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Alexander T Adams
- Department of Biochemistry & Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Terry Magnuson
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Genetics, The Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Ian J Davis
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Genetics, The Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA; Departments of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Brian D Strahl
- Department of Biochemistry & Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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16
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Williamson AK, Zhu Z, Yuan ZM. Epigenetic mechanisms behind cellular sensitivity to DNA damage. Cell Stress 2018; 2:176-180. [PMID: 31225484 PMCID: PMC6551799 DOI: 10.15698/cst2018.07.145] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Epigenetic regulation of gene expression in cells is a complex and dynamic process that remains incompletely understood. The architecture of the chromatin itself and its level of condensation can greatly impact the expression of genes as well as the sensitivity of the DNA to damage. The compact nature of heterochromatin typically results in gene silencing and resistance to DNA-damaging agents, while less compact euchromatin results in gene expression and increased sensitivity to injury. There are diverse ways in which the chromatin structure, and therefore the sensitivity of cells to damage, can be regulated, including post-translational modifications to both the histones within the chromatin and the DNA itself. These modifications are tightly controlled and correspond to various factors such as metabolism and cell cycle. When these processes are dysregulated, as in cancer cells, the chromatin structure is also altered, ultimately changing the gene expression profile as well as the susceptibility of cells to DNA-damaging agents commonly used for cancer treatments. Recent studies have shown that manipulating the various players involved in regulating post-translational modifications to chromatin and exploiting differences in metabolism may prove to be effective methods for modifying cancer and normal cell sensitivity to damaging agents. In this review we discuss various ways of regulating chromatin structure and how these changes can influence cellular sensitivity to damage as well as the implications of these relationships for improving the efficacy and safety of cancer treatments.
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Affiliation(s)
- Amanda K Williamson
- Department of Environmental Health, John B. Little Center for Radiation Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Zijing Zhu
- Department of Environmental Health, John B. Little Center for Radiation Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Zhi-Min Yuan
- Department of Environmental Health, John B. Little Center for Radiation Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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17
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Soufi A, Dalton S. Cycling through developmental decisions: how cell cycle dynamics control pluripotency, differentiation and reprogramming. Development 2017; 143:4301-4311. [PMID: 27899507 DOI: 10.1242/dev.142075] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A strong connection exists between the cell cycle and mechanisms required for executing cell fate decisions in a wide-range of developmental contexts. Terminal differentiation is often associated with cell cycle exit, whereas cell fate switches are frequently linked to cell cycle transitions in dividing cells. These phenomena have been investigated in the context of reprogramming, differentiation and trans-differentiation but the underpinning molecular mechanisms remain unclear. Most progress to address the connection between cell fate and the cell cycle has been made in pluripotent stem cells, in which the transition through mitosis and G1 phase is crucial for establishing a window of opportunity for pluripotency exit and the initiation of differentiation. This Review will summarize recent developments in this area and place them in a broader context that has implications for a wide range of developmental scenarios.
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Affiliation(s)
- Abdenour Soufi
- Institute of Stem Cell Research, MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - Stephen Dalton
- Center for Molecular Medicine and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
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18
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Luo H, Xi Y, Li W, Li J, Li Y, Dong S, Peng L, Liu Y, Yu W. Cell identity bookmarking through heterogeneous chromatin landscape maintenance during the cell cycle. Hum Mol Genet 2017; 26:4231-4243. [DOI: 10.1093/hmg/ddx312] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 08/02/2017] [Indexed: 12/29/2022] Open
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19
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Wang Y, van Merwyk L, Tönsing K, Walhorn V, Anselmetti D, Fernàndez-Busquets X. Biophysical characterization of the association of histones with single-stranded DNA. Biochim Biophys Acta Gen Subj 2017; 1861:2739-2749. [PMID: 28756274 DOI: 10.1016/j.bbagen.2017.07.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 07/19/2017] [Accepted: 07/24/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Despite the profound current knowledge of the architecture and dynamics of nucleosomes, little is known about the structures generated by the interaction of histones with single-stranded DNA (ssDNA), which is widely present during replication and transcription. METHODS Non-denaturing gel electrophoresis, transmission electron microscopy, atomic force microscopy, magnetic tweezers. RESULTS Histones have a high affinity for ssDNA in 0.15M NaCl ionic strength, with an apparent binding constant similar to that calculated for their association with double-stranded DNA (dsDNA). The length of DNA (number of nucleotides in ssDNA or base pairs in dsDNA) associated with a fixed core histone mass is the same for both ssDNA and dsDNA. Although histone-ssDNA complexes show a high tendency to aggregate, nucleosome-like structures are formed at physiological salt concentrations. Core histones are able to protect ssDNA from digestion by micrococcal nuclease, and a shortening of ssDNA occurs upon its interaction with histones. The purified (+) strand of a cloned DNA fragment of nucleosomal origin has a higher affinity for histones than the purified complementary (-) strand. CONCLUSIONS At physiological ionic strength histones have high affinity for ssDNA, possibly associating with it into nucleosome-like structures. GENERAL SIGNIFICANCE In the cell nucleus histones may spontaneously interact with ssDNA to facilitate their participation in the replication and transcription of chromatin.
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Affiliation(s)
- Ying Wang
- Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Bielefeld 33615, Germany
| | - Luis van Merwyk
- Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Bielefeld 33615, Germany
| | - Katja Tönsing
- Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Bielefeld 33615, Germany
| | - Volker Walhorn
- Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Bielefeld 33615, Germany
| | - Dario Anselmetti
- Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Bielefeld 33615, Germany
| | - Xavier Fernàndez-Busquets
- Nanomalaria Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain; Barcelona Institute for Global Health (ISGlobal), Barcelona Center for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Rosselló 149-153, Barcelona 08036, Spain; Nanoscience and Nanotechnology Institute (IN2UB), University of Barcelona, Martí i Franquès 1, Barcelona 08028, Spain.
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20
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Understanding nucleosome dynamics and their links to gene expression and DNA replication. Nat Rev Mol Cell Biol 2017; 18:548-562. [PMID: 28537572 DOI: 10.1038/nrm.2017.47] [Citation(s) in RCA: 309] [Impact Index Per Article: 44.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Advances in genomics technology have provided the means to probe myriad chromatin interactions at unprecedented spatial and temporal resolution. This has led to a profound understanding of nucleosome organization within the genome, revealing that nucleosomes are highly dynamic. Nucleosome dynamics are governed by a complex interplay of histone composition, histone post-translational modifications, nucleosome occupancy and positioning within chromatin, which are influenced by numerous regulatory factors, including general regulatory factors, chromatin remodellers, chaperones and polymerases. It is now known that these dynamics regulate diverse cellular processes ranging from gene transcription to DNA replication and repair.
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21
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Bascom GD, Kim T, Schlick T. Kilobase Pair Chromatin Fiber Contacts Promoted by Living-System-Like DNA Linker Length Distributions and Nucleosome Depletion. J Phys Chem B 2017; 121:3882-3894. [PMID: 28299939 DOI: 10.1021/acs.jpcb.7b00998] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Nucleosome placement, or DNA linker length patterns, are believed to yield specific spatial features in chromatin fibers, but details are unknown. Here we examine by mesoscale modeling how kilobase (kb) range contacts and fiber looping depend on linker lengths ranging from 18 to 45 bp, with values modeled after living systems, including nucleosome free regions (NFRs) and gene encoding segments. We also compare artificial constructs with alternating versus randomly distributed linker lengths in the range of 18-72 bp. We show that nonuniform distributions with NFRs enhance flexibility and encourage kb-range contacts. NFRs between neighboring gene segments diminish short-range contacts between flanking nucleosomes, while enhancing kb-range contacts via hierarchical looping. We also demonstrate that variances in linker lengths enhance such contacts. In particular, moderate sized variations in fiber linker lengths (∼27 bp) encourage long-range contacts in randomly distributed linker length fibers. Our work underscores the importance of linker length patterns, alongside bound proteins, in biological regulation. Contacts formed by kb-range chromatin folding are crucial to gene activity. Because we find that special linker length distributions in living systems promote kb contacts, our work suggests ways to manipulate these patterns for regulation of gene activity.
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Affiliation(s)
- Gavin D Bascom
- Department of Chemistry, New York University , 100 Washington Square E, New York, New York 10003, United States
| | - Taejin Kim
- Department of Chemistry, New York University , 100 Washington Square E, New York, New York 10003, United States
| | - Tamar Schlick
- Department of Chemistry, New York University , 100 Washington Square E, New York, New York 10003, United States.,Courant Institute of Mathematical Sciences, New York University , 251 Mercer St, New York, New York 10012, United States.,New York University-East China Normal University Center for Computational Chemistry at New York University Shanghai , Room 340, Geography Building, North Zhongshan Road, 3663 Shanghai, China
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22
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Bowman GD, McKnight JN. Sequence-specific targeting of chromatin remodelers organizes precisely positioned nucleosomes throughout the genome. Bioessays 2016; 39:1-8. [PMID: 27862071 DOI: 10.1002/bies.201600183] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Eukaryotic genomes are functionally organized into chromatin, a compact packaging of nucleoproteins with the basic repeating unit known as the nucleosome. A major focus for the chromatin field has been understanding what rules govern nucleosome positioning throughout the genome, and here we review recent findings using a novel, sequence-targeted remodeling enzyme. Nucleosomes are often packed into evenly spaced arrays that are reproducibly positioned, but how such organization is established and maintained through dramatic events such as DNA replication is poorly understood. We hypothesize that a major fraction of positioned nucleosomes arises from sequence-specific targeting of chromatin remodelers to generate "founding" nucleosomes, providing reproducible, predictable, and condition-specific nucleation sites against which neighboring nucleosomes are packed into evenly spaced arrays.
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Affiliation(s)
- Gregory D Bowman
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
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23
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Ball DA, Mehta GD, Salomon-Kent R, Mazza D, Morisaki T, Mueller F, McNally JG, Karpova TS. Single molecule tracking of Ace1p in Saccharomyces cerevisiae defines a characteristic residence time for non-specific interactions of transcription factors with chromatin. Nucleic Acids Res 2016; 44:e160. [PMID: 27566148 PMCID: PMC5137432 DOI: 10.1093/nar/gkw744] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 08/05/2016] [Accepted: 08/15/2016] [Indexed: 12/26/2022] Open
Abstract
In vivo single molecule tracking has recently developed into a powerful technique for measuring and understanding the transient interactions of transcription factors (TF) with their chromatin response elements. However, this method still lacks a solid foundation for distinguishing between specific and non-specific interactions. To address this issue, we took advantage of the power of molecular genetics of yeast. Yeast TF Ace1p has only five specific sites in the genome and thus serves as a benchmark to distinguish specific from non-specific binding. Here, we show that the estimated residence time of the short-residence molecules is essentially the same for Hht1p, Ace1p and Hsf1p, equaling 0.12-0.32 s. These three DNA-binding proteins are very different in their structure, function and intracellular concentration. This suggests that (i) short-residence molecules are bound to DNA non-specifically, and (ii) that non-specific binding shares common characteristics between vastly different DNA-bound proteins and thus may have a common underlying mechanism. We develop new and robust procedure for evaluation of adverse effects of labeling, and new quantitative analysis procedures that significantly improve residence time measurements by accounting for fluorophore blinking. Our results provide a framework for the reliable performance and analysis of single molecule TF experiments in yeast.
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Affiliation(s)
- David A Ball
- CCR/LRBGE Optical Microscopy Core, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gunjan D Mehta
- CCR/LRBGE Optical Microscopy Core, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ronit Salomon-Kent
- CCR/LRBGE Optical Microscopy Core, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Davide Mazza
- Istituto Scientifico Ospedale San Raffaele, Centro di Imaging Sperimentale e Università Vita-Salute San Raffaele, Milan 20132, Italy
| | - Tatsuya Morisaki
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Florian Mueller
- Institut Pasteur, Computation Imaging and Modeling Unit, CNRS, URA 2582, Paris 75015, France
| | - James G McNally
- Institute for Soft Matter and Functional Materials, Helmholtz Center Berlin, Berlin 12489, Germany
| | - Tatiana S Karpova
- CCR/LRBGE Optical Microscopy Core, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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24
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Pasi M, Lavery R. Structure and dynamics of DNA loops on nucleosomes studied with atomistic, microsecond-scale molecular dynamics. Nucleic Acids Res 2016; 44:5450-6. [PMID: 27098037 PMCID: PMC4914111 DOI: 10.1093/nar/gkw293] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 04/08/2016] [Accepted: 04/08/2016] [Indexed: 01/25/2023] Open
Abstract
DNA loop formation on nucleosomes is strongly implicated in chromatin remodeling and occurs spontaneously in nucleosomes subjected to superhelical stress. The nature of such loops depends crucially on the balance between DNA deformation and DNA interaction with the nucleosome core. Currently, no high-resolution structural data on these loops exist. Although uniform rod models have been used to study loop size and shape, these models make assumptions concerning DNA mechanics and DNA-core binding. We present here atomic-scale molecular dynamics simulations for two different loop sizes. The results point to the key role of localized DNA kinking within the loops. Kinks enable the relaxation of DNA bending strain to be coupled with improved DNA-core interactions. Kinks lead to small, irregularly shaped loops that are asymmetrically positioned with respect to the nucleosome core. We also find that loop position can influence the dynamics of the DNA segments at the extremities of the nucleosome.
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Affiliation(s)
- Marco Pasi
- MMSB, University Lyon I/CNRS UMR 5086, Institut de Biologie et Chimie des Protéines, 7 passage du Vercors, 69367 Lyon, France
| | - Richard Lavery
- MMSB, University Lyon I/CNRS UMR 5086, Institut de Biologie et Chimie des Protéines, 7 passage du Vercors, 69367 Lyon, France
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25
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Fennessy RT, Owen-Hughes T. Establishment of a promoter-based chromatin architecture on recently replicated DNA can accommodate variable inter-nucleosome spacing. Nucleic Acids Res 2016; 44:7189-203. [PMID: 27106059 PMCID: PMC5009725 DOI: 10.1093/nar/gkw331] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/15/2016] [Indexed: 12/18/2022] Open
Abstract
Nucleosomes, the fundamental subunits of eukaryotic chromatin, are organized with respect to transcriptional start sites. A major challenge to the persistence of this organization is the disassembly of nucleosomes during DNA replication. Here, we use complimentary approaches to map the locations of nucleosomes on recently replicated DNA. We find that nucleosomes are substantially realigned with promoters during the minutes following DNA replication. As a result, the nucleosomal landscape is largely re-established before newly replicated chromosomes are partitioned into daughter cells and can serve as a platform for the re-establishment of gene expression programmes. When the supply of histones is disrupted through mutation of the chaperone Caf1, a promoter-based architecture is generated, but with increased inter-nucleosomal spacing. This indicates that the chromatin remodelling enzymes responsible for spacing nucleosomes are capable of organizing nucleosomes with a range of different linker DNA lengths.
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Affiliation(s)
- Ross T Fennessy
- Centre for Gene Regulation and Expression, School of Life Sceinces, University of Dundee, Dundee, DD1 5EH, UK
| | - Tom Owen-Hughes
- Centre for Gene Regulation and Expression, School of Life Sceinces, University of Dundee, Dundee, DD1 5EH, UK
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