1
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Pal S, Dhar R. Living in a noisy world-origins of gene expression noise and its impact on cellular decision-making. FEBS Lett 2024; 598:1673-1691. [PMID: 38724715 DOI: 10.1002/1873-3468.14898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 03/23/2024] [Accepted: 03/27/2024] [Indexed: 07/23/2024]
Abstract
The expression level of a gene can vary between genetically identical cells under the same environmental condition-a phenomenon referred to as gene expression noise. Several studies have now elucidated a central role of transcription factors in the generation of expression noise. Transcription factors, as the key components of gene regulatory networks, drive many important cellular decisions in response to cellular and environmental signals. Therefore, a very relevant question is how expression noise impacts gene regulation and influences cellular decision-making. In this Review, we summarize the current understanding of the molecular origins of expression noise, highlighting the role of transcription factors in this process, and discuss the ways in which noise can influence cellular decision-making. As advances in single-cell technologies open new avenues for studying expression noise as well as gene regulatory circuits, a better understanding of the influence of noise on cellular decisions will have important implications for many biological processes.
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Affiliation(s)
- Sampriti Pal
- Department of Bioscience and Biotechnology, IIT Kharagpur, India
| | - Riddhiman Dhar
- Department of Bioscience and Biotechnology, IIT Kharagpur, India
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2
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Dennis AF, Xu Z, Clark DJ. Examining chromatin heterogeneity through PacBio long-read sequencing of M.EcoGII methylated genomes: an m6A detection efficiency and calling bias correcting pipeline. Nucleic Acids Res 2024; 52:e45. [PMID: 38634798 PMCID: PMC11109960 DOI: 10.1093/nar/gkae288] [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: 01/22/2024] [Revised: 03/23/2024] [Accepted: 04/04/2024] [Indexed: 04/19/2024] Open
Abstract
Recent studies have combined DNA methyltransferase footprinting of genomic DNA in nuclei with long-read sequencing, resulting in detailed chromatin maps for multi-kilobase stretches of genomic DNA from one cell. Theoretically, nucleosome footprints and nucleosome-depleted regions can be identified using M.EcoGII, which methylates adenines in any sequence context, providing a high-resolution map of accessible regions in each DNA molecule. Here, we report PacBio long-read sequence data for budding yeast nuclei treated with M.EcoGII and a bioinformatic pipeline which corrects for three key challenges undermining this promising method. First, detection of m6A in individual DNA molecules by the PacBio software is inefficient, resulting in false footprints predicted by random gaps of seemingly unmethylated adenines. Second, there is a strong bias against m6A base calling as AT content increases. Third, occasional methylation occurs within nucleosomes, breaking up their footprints. After correcting for these issues, our pipeline calculates a correlation coefficient-based score indicating the extent of chromatin heterogeneity within the cell population for every gene. Although the population average is consistent with that derived using other techniques, we observe a wide range of heterogeneity in nucleosome positions at the single-molecule level, probably reflecting cellular chromatin dynamics.
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Affiliation(s)
- Allison F Dennis
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhuwei Xu
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - David J Clark
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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3
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Dennis AF, Xu Z, Clark DJ. Examining chromatin heterogeneity through PacBio long-read sequencing of M.EcoGII methylated genomes: an m 6A detection efficiency and calling bias correcting pipeline. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569045. [PMID: 38076871 PMCID: PMC10705563 DOI: 10.1101/2023.11.28.569045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Recent studies have combined DNA methyltransferase footprinting of genomic DNA in nuclei with long-read sequencing, resulting in detailed chromatin maps for multi-kilobase stretches of genomic DNA from one cell. Theoretically, nucleosome footprints and nucleosome-depleted regions can be identified using M.EcoGII, which methylates adenines in any sequence context, providing a high-resolution map of accessible regions in each DNA molecule. Here we report PacBio long-read sequence data for budding yeast nuclei treated with M.EcoGII and a bioinformatic pipeline which corrects for three key challenges undermining this promising method. First, detection of m6A in individual DNA molecules by the PacBio software is inefficient, resulting in false footprints predicted by random gaps of seemingly unmethylated adenines. Second, there is a strong bias against m6A base calling as AT content increases. Third, occasional methylation occurs within nucleosomes, breaking up their footprints. After correcting for these issues, our pipeline calculates a correlation coefficient-based score indicating the extent of chromatin heterogeneity within the cell population for every gene. Although the population average is consistent with that derived using other techniques, we observe a wide range of heterogeneity in nucleosome positions at the single-molecule level, probably reflecting cellular chromatin dynamics.
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Affiliation(s)
| | | | - David J. Clark
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
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4
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Kleinschmidt H, Xu C, Bai L. Using Synthetic DNA Libraries to Investigate Chromatin and Gene Regulation. Chromosoma 2023; 132:167-189. [PMID: 37184694 PMCID: PMC10542970 DOI: 10.1007/s00412-023-00796-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/16/2023]
Abstract
Despite the recent explosion in genome-wide studies in chromatin and gene regulation, we are still far from extracting a set of genetic rules that can predict the function of the regulatory genome. One major reason for this deficiency is that gene regulation is a multi-layered process that involves an enormous variable space, which cannot be fully explored using native genomes. This problem can be partially solved by introducing synthetic DNA libraries into cells, a method that can test the regulatory roles of thousands to millions of sequences with limited variables. Here, we review recent applications of this method to study transcription factor (TF) binding, nucleosome positioning, and transcriptional activity. We discuss the design principles, experimental procedures, and major findings from these studies and compare the pros and cons of different approaches.
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Affiliation(s)
- Holly Kleinschmidt
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Cheng Xu
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Lu Bai
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA.
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5
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Zion EH, Ringwalt D, Rinaldi K, Kahney EW, Li Y, Chen X. Old and newly synthesized histones are asymmetrically distributed in Drosophila intestinal stem cell divisions. EMBO Rep 2023; 24:e56404. [PMID: 37255015 PMCID: PMC10328082 DOI: 10.15252/embr.202256404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 04/30/2023] [Accepted: 05/16/2023] [Indexed: 06/01/2023] Open
Abstract
We report that preexisting (old) and newly synthesized (new) histones H3 and H4 are asymmetrically partitioned during the division of Drosophila intestinal stem cells (ISCs). Furthermore, the inheritance patterns of old and new H3 and H4 in postmitotic cell pairs correlate with distinct expression patterns of Delta, an important cell fate gene. To understand the biological significance of this phenomenon, we expressed a mutant H3T3A to compromise asymmetric histone inheritance. Under this condition, we observe an increase in Delta-symmetric cell pairs and overpopulated ISC-like, Delta-positive cells. Single-cell RNA-seq assays further indicate that H3T3A expression compromises ISC differentiation. Together, our results indicate that asymmetric histone inheritance potentially contributes to establishing distinct cell identities in a somatic stem cell lineage, consistent with previous findings in Drosophila male germline stem cells.
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Affiliation(s)
- Emily H Zion
- Department of BiologyThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Daniel Ringwalt
- Department of BiologyThe Johns Hopkins UniversityBaltimoreMDUSA
| | | | | | - Yingying Li
- Department of BiologyThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Xin Chen
- Department of BiologyThe Johns Hopkins UniversityBaltimoreMDUSA
- Howard Hughes Medical InstituteBaltimoreMDUSA
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6
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Brouwer I, Kerklingh E, van Leeuwen F, Lenstra TL. Dynamic epistasis analysis reveals how chromatin remodeling regulates transcriptional bursting. Nat Struct Mol Biol 2023; 30:692-702. [PMID: 37127821 DOI: 10.1038/s41594-023-00981-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/30/2023] [Indexed: 05/03/2023]
Abstract
Transcriptional bursting has been linked to the stochastic positioning of nucleosomes. However, how bursting is regulated by the remodeling of promoter nucleosomes is unknown. Here, we use single-molecule live-cell imaging of GAL10 transcription in Saccharomyces cerevisiae to measure how bursting changes upon combined perturbations of chromatin remodelers, the transcription factor Gal4 and preinitiation complex components. Using dynamic epistasis analysis, we reveal how the remodeling of different nucleosomes regulates transcriptional bursting parameters. At the nucleosome covering the Gal4 binding sites, RSC and Gal4 binding synergistically facilitate each burst. Conversely, nucleosome remodeling at the TATA box controls only the first burst upon galactose induction. At canonical TATA boxes, the nucleosomes are displaced by TBP binding to allow for transcription activation even in the absence of remodelers. Overall, our results reveal how promoter nucleosome remodeling together with Gal4 and preinitiation complex binding regulates transcriptional bursting.
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Affiliation(s)
- Ineke Brouwer
- Division of Gene Regulation, the Netherlands Cancer Institute, Oncode Institute, Amsterdam, the Netherlands
| | - Emma Kerklingh
- Division of Gene Regulation, the Netherlands Cancer Institute, Oncode Institute, Amsterdam, the Netherlands
| | - Fred van Leeuwen
- Division of Gene Regulation, the Netherlands Cancer Institute, Amsterdam, the Netherlands
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, the Netherlands Cancer Institute, Oncode Institute, Amsterdam, the Netherlands.
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7
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Parab L, Pal S, Dhar R. Transcription factor binding process is the primary driver of noise in gene expression. PLoS Genet 2022; 18:e1010535. [PMID: 36508455 PMCID: PMC9779669 DOI: 10.1371/journal.pgen.1010535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 12/22/2022] [Accepted: 11/16/2022] [Indexed: 12/14/2022] Open
Abstract
Noise in expression of individual genes gives rise to variations in activity of cellular pathways and generates heterogeneity in cellular phenotypes. Phenotypic heterogeneity has important implications for antibiotic persistence, mutation penetrance, cancer growth and therapy resistance. Specific molecular features such as the presence of the TATA box sequence and the promoter nucleosome occupancy have been associated with noise. However, the relative importance of these features in noise regulation is unclear and how well these features can predict noise has not yet been assessed. Here through an integrated statistical model of gene expression noise in yeast we found that the number of regulating transcription factors (TFs) of a gene was a key predictor of noise, whereas presence of the TATA box and the promoter nucleosome occupancy had poor predictive power. With an increase in the number of regulatory TFs, there was a rise in the number of cooperatively binding TFs. In addition, an increased number of regulatory TFs meant more overlaps in TF binding sites, resulting in competition between TFs for binding to the same region of the promoter. Through modeling of TF binding to promoter and application of stochastic simulations, we demonstrated that competition and cooperation among TFs could increase noise. Thus, our work uncovers a process of noise regulation that arises out of the dynamics of gene regulation and is not dependent on any specific transcription factor or specific promoter sequence.
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Affiliation(s)
- Lavisha Parab
- Department of Biotechnology, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, West Bengal, India
- Max-Planck-Institute for Evolutionary Biology, Plön, Germany
| | - Sampriti Pal
- Department of Biotechnology, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, West Bengal, India
| | - Riddhiman Dhar
- Department of Biotechnology, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, West Bengal, India
- * E-mail:
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8
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Li S, Peng Y, Landsman D, Panchenko AR. DNA methylation cues in nucleosome geometry, stability and unwrapping. Nucleic Acids Res 2022; 50:1864-1874. [PMID: 35166834 DOI: 10.1093/nar/gkac097] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 01/29/2022] [Accepted: 02/01/2022] [Indexed: 01/04/2023] Open
Abstract
Cytosine methylation at the 5-carbon position is an essential DNA epigenetic mark in many eukaryotic organisms. Although countless structural and functional studies of cytosine methylation have been reported, our understanding of how it influences the nucleosome assembly, structure, and dynamics remains obscure. Here, we investigate the effects of cytosine methylation at CpG sites on nucleosome dynamics and stability. By applying long molecular dynamics simulations on several microsecond time scale, we generate extensive atomistic conformational ensembles of full nucleosomes. Our results reveal that methylation induces pronounced changes in geometry for both linker and nucleosomal DNA, leading to a more curved, under-twisted DNA, narrowing the adjacent minor grooves, and shifting the population equilibrium of sugar-phosphate backbone geometry. These DNA conformational changes are associated with a considerable enhancement of interactions between methylated DNA and the histone octamer, doubling the number of contacts at some key arginines. H2A and H3 tails play important roles in these interactions, especially for DNA methylated nucleosomes. This, in turn, prevents a spontaneous DNA unwrapping of 3-4 helical turns for the methylated nucleosome with truncated histone tails, otherwise observed in the unmethylated system on several microseconds time scale.
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Affiliation(s)
- Shuxiang Li
- Department of Pathology and Molecular Medicine, School of Medicine, Queen's University, ON, Canada
| | - Yunhui Peng
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD, USA
| | - David Landsman
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD, USA
| | - Anna R Panchenko
- Department of Pathology and Molecular Medicine, School of Medicine, Queen's University, ON, Canada
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9
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Brandani GB, Tan C, Takada S. The kinetic landscape of nucleosome assembly: A coarse-grained molecular dynamics study. PLoS Comput Biol 2021; 17:e1009253. [PMID: 34314440 PMCID: PMC8345847 DOI: 10.1371/journal.pcbi.1009253] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 08/06/2021] [Accepted: 07/06/2021] [Indexed: 11/23/2022] Open
Abstract
The organization of nucleosomes along the Eukaryotic genome is maintained over time despite disruptive events such as replication. During this complex process, histones and DNA can form a variety of non-canonical nucleosome conformations, but their precise molecular details and roles during nucleosome assembly remain unclear. In this study, employing coarse-grained molecular dynamics simulations and Markov state modeling, we characterized the complete kinetics of nucleosome assembly. On the nucleosome-positioning 601 DNA sequence, we observe a rich transition network among various canonical and non-canonical tetrasome, hexasome, and nucleosome conformations. A low salt environment makes nucleosomes stable, but the kinetic landscape becomes more rugged, so that the system is more likely to be trapped in off-pathway partially assembled intermediates. Finally, we find that the co-operativity between DNA bending and histone association enables positioning sequence motifs to direct the assembly process, with potential implications for the dynamic organization of nucleosomes on real genomic sequences. Nucleosomes are biomolecular complexes formed by DNA wrapped around histone proteins. They represent the basic units of Eukaryotic chromosomes, compacting the genome so that it fits into the small nucleus, and regulating important biological processes such as gene expression. Nucleosomes are disassembled during disruptive events such as DNA replication, and re-assembled afterwards to preserve the correct organization of chromatin. However, the molecular details of nucleosome assembly are still not well understood. In particular, experiments found that histones and DNA may associate into a variety of non-canonical complexes, but their precise conformation and role during assembly remain unclear. In this study, we addressed these problems by performing extensive molecular dynamics simulations of nucleosomes undergoing assembly and disassembly. The simulations reveal many insights into the kinetics of assembly, the structure of non-canonical nucleosome intermediates, and the influence of salt concentration and DNA sequence on the assembly process.
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Affiliation(s)
- Giovanni B. Brandani
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
- * E-mail: (GBB); (ST)
| | - Cheng Tan
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
- * E-mail: (GBB); (ST)
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10
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Mehrmohamadi M, Sepehri MH, Nazer N, Norouzi MR. A Comparative Overview of Epigenomic Profiling Methods. Front Cell Dev Biol 2021; 9:714687. [PMID: 34368164 PMCID: PMC8340004 DOI: 10.3389/fcell.2021.714687] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/30/2021] [Indexed: 11/13/2022] Open
Abstract
In the past decade, assays that profile different aspects of the epigenome have grown exponentially in number and variation. However, standard guidelines for researchers to choose between available tools depending on their needs are lacking. Here, we introduce a comprehensive collection of the most commonly used bulk and single-cell epigenomic assays and compare and contrast their strengths and weaknesses. We summarize some of the most important technical and experimental parameters that should be considered for making an appropriate decision when designing epigenomic experiments.
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Affiliation(s)
- Mahya Mehrmohamadi
- Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran
| | | | - Naghme Nazer
- Department of Electrical Engineering, Sharif University of Technology, Tehran, Iran
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11
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Ishihara S, Sasagawa Y, Kameda T, Yamashita H, Umeda M, Kotomura N, Abe M, Shimono Y, Nikaido I. Local states of chromatin compaction at transcription start sites control transcription levels. Nucleic Acids Res 2021; 49:8007-8023. [PMID: 34233004 PMCID: PMC8373074 DOI: 10.1093/nar/gkab587] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 06/12/2021] [Accepted: 06/30/2021] [Indexed: 11/16/2022] Open
Abstract
The ‘open’ and ‘compact’ regions of chromatin are considered to be regions of active and silent transcription, respectively. However, individual genes produce transcripts at different levels, suggesting that transcription output does not depend on the simple open-compact conversion of chromatin, but on structural variations in chromatin itself, which so far have remained elusive. In this study, weakly crosslinked chromatin was subjected to sedimentation velocity centrifugation, which fractionated the chromatin according to its degree of compaction. Open chromatin remained in upper fractions, while compact chromatin sedimented to lower fractions depending on the level of nucleosome assembly. Although nucleosomes were evenly detected in all fractions, histone H1 was more highly enriched in the lower fractions. H1 was found to self-associate and crosslinked to histone H3, suggesting that H1 bound to H3 interacts with another H1 in an adjacent nucleosome to form compact chromatin. Genome-wide analyses revealed that nearly the entire genome consists of compact chromatin without differences in compaction between repeat and non-repeat sequences; however, active transcription start sites (TSSs) were rarely found in compact chromatin. Considering the inverse correlation between chromatin compaction and RNA polymerase binding at TSSs, it appears that local states of chromatin compaction determine transcription levels.
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Affiliation(s)
- Satoru Ishihara
- Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan
| | - Yohei Sasagawa
- Laboratory for Bioinformatics Research, RIKEN Center for Biosystems Dynamics Research, Wako, Saitama 351-0198, Japan.,Functional Genome Informatics, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Takeru Kameda
- Laboratory for Bioinformatics Research, RIKEN Center for Biosystems Dynamics Research, Wako, Saitama 351-0198, Japan.,Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Hayato Yamashita
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Mana Umeda
- Laboratory for Bioinformatics Research, RIKEN Center for Biosystems Dynamics Research, Wako, Saitama 351-0198, Japan
| | - Naoe Kotomura
- Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan
| | - Masayuki Abe
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yohei Shimono
- Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan
| | - Itoshi Nikaido
- Laboratory for Bioinformatics Research, RIKEN Center for Biosystems Dynamics Research, Wako, Saitama 351-0198, Japan.,Functional Genome Informatics, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan.,Master's/Doctoral Program in Life Science Innovation (Bioinformatics), Degree Programs in Systems and Information Engineering, Graduate School of Science and Technology, University of Tsukuba, Wako, Saitama 351-0198, Japan
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12
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Devenish LP, Mhlanga MM, Negishi Y. Immune Regulation in Time and Space: The Role of Local- and Long-Range Genomic Interactions in Regulating Immune Responses. Front Immunol 2021; 12:662565. [PMID: 34046034 PMCID: PMC8144502 DOI: 10.3389/fimmu.2021.662565] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/26/2021] [Indexed: 12/27/2022] Open
Abstract
Mammals face and overcome an onslaught of endogenous and exogenous challenges in order to survive. Typical immune cells and barrier cells, such as epithelia, must respond rapidly and effectively to encountered pathogens and aberrant cells to prevent invasion and eliminate pathogenic species before they become overgrown and cause harm. On the other hand, inappropriate initiation and failed termination of immune cell effector function in the absence of pathogens or aberrant tissue gives rise to a number of chronic, auto-immune, and neoplastic diseases. Therefore, the fine control of immune effector functions to provide for a rapid, robust response to challenge is essential. Importantly, immune cells are heterogeneous due to various factors relating to cytokine exposure and cell-cell interaction. For instance, tissue-resident macrophages and T cells are phenotypically, transcriptionally, and functionally distinct from their circulating counterparts. Indeed, even the same cell types in the same environment show distinct transcription patterns at the single cell level due to cellular noise, despite being robust in concert. Additionally, immune cells must remain quiescent in a naive state to avoid autoimmunity or chronic inflammatory states but must respond robustly upon activation regardless of their microenvironment or cellular noise. In recent years, accruing evidence from next-generation sequencing, chromatin capture techniques, and high-resolution imaging has shown that local- and long-range genome architecture plays an important role in coordinating rapid and robust transcriptional responses. Here, we discuss the local- and long-range genome architecture of immune cells and the resultant changes upon pathogen or antigen exposure. Furthermore, we argue that genome structures contribute functionally to rapid and robust responses under noisy and distinct cellular environments and propose a model to explain this phenomenon.
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Affiliation(s)
- Liam P Devenish
- Division of Chemical, Systems, and Synthetic Biology, Department of Integrative Biomedical Sciences, Institute of Infectious Disease & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Musa M Mhlanga
- Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University Medical Center, Nijmegen, Netherlands.,Epigenomics & Single Cell Biophysics Group, Department of Cell Biology, Radboud University, Nijmegen, Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
| | - Yutaka Negishi
- Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University Medical Center, Nijmegen, Netherlands.,Epigenomics & Single Cell Biophysics Group, Department of Cell Biology, Radboud University, Nijmegen, Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
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13
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Capp J. Interplay between genetic, epigenetic, and gene expression variability: Considering complexity in evolvability. Evol Appl 2021; 14:893-901. [PMID: 33897810 PMCID: PMC8061278 DOI: 10.1111/eva.13204] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/27/2021] [Accepted: 01/30/2021] [Indexed: 12/11/2022] Open
Abstract
Genetic variability, epigenetic variability, and gene expression variability (noise) are generally considered independently in their relationship with phenotypic variation. However, they appear to be intrinsically interconnected and influence it in combination. The study of the interplay between genetic and epigenetic variability has the longest history. This article rather considers the introduction of gene expression variability in its relationships with the two others and reviews for the first time experimental evidences over the four relationships connected to gene expression noise. They show how introducing this third source of variability complicates the way of thinking evolvability and the emergence of biological novelty. Finally, cancer cells are proposed to be an ideal model to decipher the dynamic interplay between genetic, epigenetic, and gene expression variability when one of them is either experimentally increased or therapeutically targeted. This interplay is also discussed in an evolutionary perspective in the context of cancer cell drug resistance.
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Affiliation(s)
- Jean‐Pascal Capp
- Toulouse Biotechnology InstituteINSACNRSINRAEUniversity of ToulouseToulouseFrance
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14
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Wolff MR, Schmid A, Korber P, Gerland U. Effective dynamics of nucleosome configurations at the yeast PHO5 promoter. eLife 2021; 10:58394. [PMID: 33666171 PMCID: PMC8004102 DOI: 10.7554/elife.58394] [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: 04/29/2020] [Accepted: 03/04/2021] [Indexed: 12/11/2022] Open
Abstract
Chromatin dynamics are mediated by remodeling enzymes and play crucial roles in gene regulation, as established in a paradigmatic model, the Saccharomyces cerevisiae PHO5 promoter. However, effective nucleosome dynamics, that is, trajectories of promoter nucleosome configurations, remain elusive. Here, we infer such dynamics from the integration of published single-molecule data capturing multi-nucleosome configurations for repressed to fully active PHO5 promoter states with other existing histone turnover and new chromatin accessibility data. We devised and systematically investigated a new class of 'regulated on-off-slide' models simulating global and local nucleosome (dis)assembly and sliding. Only seven of 68,145 models agreed well with all data. All seven models involve sliding and the known central role of the N-2 nucleosome, but regulate promoter state transitions by modulating just one assembly rather than disassembly process. This is consistent with but challenges common interpretations of previous observations at the PHO5 promoter and suggests chromatin opening by binding competition.
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Affiliation(s)
| | - Andrea Schmid
- Molecular Biology Division, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Philipp Korber
- Molecular Biology Division, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Ulrich Gerland
- Department of Physics, Technical University of Munich, Garching, Germany
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15
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Hou J, Li X, Xie KP. Coupled liquid biopsy and bioinformatics for pancreatic cancer early detection and precision prognostication. Mol Cancer 2021; 20:34. [PMID: 33593396 PMCID: PMC7888169 DOI: 10.1186/s12943-021-01309-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/06/2021] [Indexed: 02/08/2023] Open
Abstract
Early detection and diagnosis are the key to successful clinical management of pancreatic cancer and improve the patient outcome. However, due to the absence of early symptoms and the aggressiveness of pancreatic cancer, its 5-year survival rate remains below 5 %. Compared to tissue samples, liquid biopsies are of particular interest in clinical settings with respect to minimal invasiveness, repeated sampling, complete representation of the entire or multi-site tumor bulks. The potential of liquid biopsies in pancreatic cancer has been demonstrated by many studies which prove that liquid biopsies are able to detect early emergency of pancreatic cancer cells, residual disease, and recurrence. More interestingly, they show potential to delineate the heterogeneity, spatial and temporal, of pancreatic cancer. However, the performance of liquid biopsies for the diagnosis varies largely across different studies depending of the technique employed and also the type and stage of the tumor. One approach to improve the detect performance of liquid biopsies is to intensively inspect circulome and to define integrated biomarkers which simultaneously profile circulating tumor cells and DNA, extracellular vesicles, and circulating DNA, or cell free DNA and proteins. Moreover, the diagnostic validity and accuracy of liquid biopsies still need to be comprehensively demonstrated and validated.
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Affiliation(s)
- Jun Hou
- The South China University of Technology School of Medicine, 510006, Guangzhou, China
| | - XueTao Li
- The South China University of Technology School of Medicine, 510006, Guangzhou, China
| | - Ke-Ping Xie
- The University of Texas MD Anderson Cancer Center Houston , Texas, USA.
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16
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Nucleosome Positioning and Spacing: From Mechanism to Function. J Mol Biol 2021; 433:166847. [PMID: 33539878 DOI: 10.1016/j.jmb.2021.166847] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 01/16/2021] [Accepted: 01/22/2021] [Indexed: 02/08/2023]
Abstract
Eukaryotes associate their genomes with histone proteins, forming nucleosome particles. Nucleosomes regulate and protect the genetic information. They often assemble into evenly spaced arrays of nucleosomes. These regular nucleosome arrays cover significant portions of the genome, in particular over genes. The presence of these evenly spaced nucleosome arrays is highly conserved throughout the entire eukaryotic domain. Here, we review the mechanisms behind the establishment of this primary structure of chromatin with special emphasis on the biogenesis of evenly spaced nucleosome arrays. We highlight the roles that transcription, nucleosome remodelers, DNA sequence, and histone density play towards the formation of evenly spaced nucleosome arrays and summarize our current understanding of their cellular functions. We end with key unanswered questions that remain to be explored to obtain an in-depth understanding of the biogenesis and function of the nucleosome landscape.
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17
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Zhu L, Marjani SL, Jiang Z. The Epigenetics of Gametes and Early Embryos and Potential Long-Range Consequences in Livestock Species-Filling in the Picture With Epigenomic Analyses. Front Genet 2021; 12:557934. [PMID: 33747031 PMCID: PMC7966815 DOI: 10.3389/fgene.2021.557934] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 02/04/2021] [Indexed: 12/31/2022] Open
Abstract
The epigenome is dynamic and forged by epigenetic mechanisms, such as DNA methylation, histone modifications, chromatin remodeling, and non-coding RNA species. Increasing lines of evidence support the concept that certain acquired traits are derived from environmental exposure during early embryonic and fetal development, i.e., fetal programming, and can even be "memorized" in the germline as epigenetic information and transmitted to future generations. Advances in technology are now driving the global profiling and precise editing of germline and embryonic epigenomes, thereby improving our understanding of epigenetic regulation and inheritance. These achievements open new avenues for the development of technologies or potential management interventions to counteract adverse conditions or improve performance in livestock species. In this article, we review the epigenetic analyses (DNA methylation, histone modification, chromatin remodeling, and non-coding RNAs) of germ cells and embryos in mammalian livestock species (cattle, sheep, goats, and pigs) and the epigenetic determinants of gamete and embryo viability. We also discuss the effects of parental environmental exposures on the epigenetics of gametes and the early embryo, and evidence for transgenerational inheritance in livestock.
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Affiliation(s)
- Linkai Zhu
- AgCenter, School of Animal Sciences, Louisiana State University, Baton Rouge, LA, United States
| | - Sadie L Marjani
- Department of Biology, Central Connecticut State University, New Britain, CT, United States
| | - Zongliang Jiang
- AgCenter, School of Animal Sciences, Louisiana State University, Baton Rouge, LA, United States
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18
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Vasdekis AE, Singh A. Microbial metabolic noise. WIREs Mech Dis 2020; 13:e1512. [PMID: 33225608 DOI: 10.1002/wsbm.1512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 09/23/2020] [Accepted: 10/26/2020] [Indexed: 11/06/2022]
Abstract
From the time a cell was first placed under the microscope, it became apparent that identifying two clonal cells that "look" identical is extremely challenging. Since then, cell-to-cell differences in shape, size, and protein content have been carefully examined, informing us of the ultimate limits that hinder two cells from occupying an identical phenotypic state. Here, we present recent experimental and computational evidence that similar limits emerge also in cellular metabolism. These limits pertain to stochastic metabolic dynamics and, thus, cell-to-cell metabolic variability, including the resulting adapting benefits. We review these phenomena with a focus on microbial metabolism and conclude with a brief outlook on the potential relationship between metabolic noise and adaptive evolution. This article is categorized under: Metabolic Diseases > Computational Models Metabolic Diseases > Biomedical Engineering.
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Affiliation(s)
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, USA
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19
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SIR2 Expression Noise Can Generate Heterogeneity in Viability but Does Not Affect Cell-to-Cell Epigenetic Silencing of Subtelomeric URA3 in Yeast. G3-GENES GENOMES GENETICS 2020; 10:3435-3443. [PMID: 32727919 PMCID: PMC7466964 DOI: 10.1534/g3.120.401589] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Chromatin structure clearly modulates gene expression noise, but the reverse influence has never been investigated, namely how the cell-to-cell expression heterogeneity of chromatin modifiers may generate variable rates of epigenetic modification. Sir2 is a well-characterized histone deacetylase of the Sirtuin family. It strongly influences chromatin silencing, especially at telomeres, subtelomeres and rDNA. This ability to influence epigenetic landscapes makes it a good model to study the largely unexplored interplay between gene expression noise and other epigenetic processes leading to phenotypic diversification. Here, we addressed this question by investigating whether noise in the expression of SIR2 was associated with cell-to-cell heterogeneity in the frequency of epigenetic silencing at subtelomeres in Saccharomyces cerevisiae Using cell sorting to isolate subpopulations with various expression levels, we found that heterogeneity in the cellular concentration of Sir2 does not lead to heterogeneity in the epigenetic silencing of subtelomeric URA3 between these subpopulations. We also noticed that SIR2 expression noise can generate cell-to-cell variability in viability, with lower levels being associated with better viability. This work shows that SIR2 expression fluctuations are not sufficient to generate cell-to-cell heterogeneity in the epigenetic silencing of URA3 at subtelomeres in Saccharomyces cerevisiae but can strongly affect cellular viability.
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20
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Parmar JJ, Padinhateeri R. Nucleosome positioning and chromatin organization. Curr Opin Struct Biol 2020; 64:111-118. [PMID: 32731156 DOI: 10.1016/j.sbi.2020.06.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 05/31/2020] [Accepted: 06/23/2020] [Indexed: 11/24/2022]
Abstract
In our cells, DNA is folded and packed with the help of many proteins into chromatin whose basic unit is a nucleosome-DNA wrapped around octamer of histone proteins. The chain of nucleosomes is further folded and arranged into many layers and has a dynamic organization. How does the complex chromatin organization emerge from interactions among DNA, histones, and non-histone proteins have been a question of great interest. Here we review recent literature that investigated how nucleosome positioning and nucleosome-mediated interactions drive chromatin organization. Unlike our earlier understanding, chromatin is organized into 3D domains of various sizes having irregularly organized nucleosomes. These domains emerge due to heterogeneous nucleosome positioning and diverse inter-nucleosome interactions that vary in space and time.
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Affiliation(s)
- Jyotsana J Parmar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400 076, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400 076, India.
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21
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Pranckeviciene E, Hosid S, Liang N, Ioshikhes I. Nucleosome positioning sequence patterns as packing or regulatory. PLoS Comput Biol 2020; 16:e1007365. [PMID: 31986131 PMCID: PMC7004410 DOI: 10.1371/journal.pcbi.1007365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 02/06/2020] [Accepted: 12/06/2019] [Indexed: 11/19/2022] Open
Abstract
Nucleosome positioning DNA sequence patterns (NPS)-usually distributions of particular dinucleotides or other sequence elements in nucleosomal DNA-at least partially determine chromatin structure and arrangements of nucleosomes that in turn affect gene expression. Statistically, NPS are defined as oscillations of the dinucleotide periodicity of about 10 base pairs (bp) which reflects the double helix period. We compared the nucleosomal DNA patterns in mouse, human and yeast organisms and observed few distinctive patterns that can be termed as packing and regulatory referring to distinctive modes of chromatin function. For the first time the NPS patterns in nucleus accumbens cells (NAC) in mouse brain were characterized and compared to the patterns in human CD4+ and apoptotic lymphocyte cells and well studied patterns in yeast. The NPS patterns in human CD4+ cells and mouse brain cells had very high positive correlation. However, there was no correlation between them and patterns in human apoptotic lymphocyte cells and yeast, but the latter two were highly correlated with each other. By their dinucleotide arrangements the analyzed NPS patterns classified into stable canonical WW/SS (W = A or T and S = C or G dinucleotide) and less stable RR/YY (R = A or G and Y = C or T dinucleotide) patterns and anti-patterns. In the anti-patterns positioning of the dinucleotides is flipped compared to those in the regular patterns. Stable canonical WW/SS patterns and anti-patterns are ubiquitously observed in many organisms and they had high resemblance between yeast and human apoptotic cells. Less stable RR/YY patterns had higher positive correlation between mouse and normal human cells. Our analysis and evidence from scientific literature lead to idea that various distinct patterns in nucleosomal DNA can be related to the two roles of the chromatin: packing (WW/SS) and regulatory (RR/YY and "anti").
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Affiliation(s)
- Erinija Pranckeviciene
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Department of Human and Medical Genetics, Biomedical Science Institute, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
- * E-mail: (EP); (II)
| | - Sergey Hosid
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Nathan Liang
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Ilya Ioshikhes
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Ottawa Institute of Systems Biology (OISB), Ottawa, Ontario, Canada
- * E-mail: (EP); (II)
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22
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Abstract
Specificity in transcriptional regulation is imparted by transcriptional activators that bind to specific DNA sequences from which they stimulate transcription. Specificity may be increased by slowing down the kinetics of regulation: by increasing the energy for dissociation of the activator-DNA complex or decreasing activator concentration. In general, higher dissociation energies imply longer DNA dwell times of the activator; the activator-bound gene may not readily turn off again. Lower activator concentrations entail longer pauses between binding events; the activator-unbound gene is not easily turned on again and activated transcription occurs in stochastic bursts. We show that kinetic proofreading of activator-DNA recognition-insertion of an energy-dissipating delay step into the activation pathway for transcription-reconciles high specificity of transcriptional regulation with fast regulatory kinetics. We show that kinetic proofreading results from the stochastic removal and reformation of promoter nucleosomes, at a distance from equilibrium.
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23
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Takada S, Brandani GB, Tan C. Nucleosomes as allosteric scaffolds for genetic regulation. Curr Opin Struct Biol 2020; 62:93-101. [PMID: 31901887 DOI: 10.1016/j.sbi.2019.11.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 12/11/2022]
Abstract
Nucleosomes are stable yet highly dynamic complexes exhibiting diverse types of motions, such as sliding, DNA unwrapping, and disassembly, encoding a landscape with a large number of metastable states. In this review, describing recent studies on these nucleosome structure changes, we propose that the nucleosome can be viewed as an ideal allosteric scaffold: regulated by effector molecules such as transcription factors and chromatin remodelers, the nucleosome controls the downstream gene activity. Binding of transcription factors to the nucleosome can enhance DNA unwrapping or slide the DNA, altering either the binding or the unbinding of other transcription factors to nearby sites. ATP-dependent chromatin remodelers induce a series of DNA deformations, which allosterically propagate throughout the nucleosome to induce DNA sliding or histone exchange.
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Affiliation(s)
- Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo Kyoto, 606-8502, Japan.
| | - Giovanni B Brandani
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo Kyoto, 606-8502, Japan
| | - Cheng Tan
- RIKEN Center for Computational Science, 7-1-26 Minatojima-minamimachi, Chuo, Kobe, 650-0047 Japan
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24
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Oberbeckmann E, Wolff M, Krietenstein N, Heron M, Ellins JL, Schmid A, Krebs S, Blum H, Gerland U, Korber P. Absolute nucleosome occupancy map for the Saccharomyces cerevisiae genome. Genome Res 2019; 29:1996-2009. [PMID: 31694866 PMCID: PMC6886505 DOI: 10.1101/gr.253419.119] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 10/31/2019] [Indexed: 12/23/2022]
Abstract
Mapping of nucleosomes, the basic DNA packaging unit in eukaryotes, is fundamental for understanding genome regulation because nucleosomes modulate DNA access by their positioning along the genome. A cell-population nucleosome map requires two observables: nucleosome positions along the DNA ("Where?") and nucleosome occupancies across the population ("In how many cells?"). All available genome-wide nucleosome mapping techniques are yield methods because they score either nucleosomal (e.g., MNase-seq, chemical cleavage-seq) or nonnucleosomal (e.g., ATAC-seq) DNA but lose track of the total DNA population for each genomic region. Therefore, they only provide nucleosome positions and maybe compare relative occupancies between positions, but cannot measure absolute nucleosome occupancy, which is the fraction of all DNA molecules occupied at a given position and time by a nucleosome. Here, we established two orthogonal and thereby cross-validating approaches to measure absolute nucleosome occupancy across the Saccharomyces cerevisiae genome via restriction enzymes and DNA methyltransferases. The resulting high-resolution (9-bp) map shows uniform absolute occupancies. Most nucleosome positions are occupied in most cells: 97% of all nucleosomes called by chemical cleavage-seq have a mean absolute occupancy of 90 ± 6% (±SD). Depending on nucleosome position calling procedures, there are 57,000 to 60,000 nucleosomes per yeast cell. The few low absolute occupancy nucleosomes do not correlate with highly transcribed gene bodies, but correlate with increased presence of the nucleosome-evicting chromatin structure remodeling (RSC) complex, and are enriched upstream of highly transcribed or regulated genes. Our work provides a quantitative method and reference frame in absolute terms for future chromatin studies.
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Affiliation(s)
- Elisa Oberbeckmann
- Molecular Biology Division, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Michael Wolff
- Physik Department, Technische Universität München, 85748 Garching, Germany
| | - Nils Krietenstein
- Molecular Biology Division, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany.,Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Mark Heron
- Quantitative and Computational Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.,Gene Center, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Jessica L Ellins
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, United Kingdom
| | - Andrea Schmid
- Molecular Biology Division, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Stefan Krebs
- Laboratory of Functional Genome Analysis (LAFUGA), Gene Center, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Helmut Blum
- Laboratory of Functional Genome Analysis (LAFUGA), Gene Center, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Ulrich Gerland
- Physik Department, Technische Universität München, 85748 Garching, Germany
| | - Philipp Korber
- Molecular Biology Division, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
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25
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Mukiza TO, Protacio RU, Davidson MK, Steiner WW, Wahls WP. Diverse DNA Sequence Motifs Activate Meiotic Recombination Hotspots Through a Common Chromatin Remodeling Pathway. Genetics 2019; 213:789-803. [PMID: 31511300 PMCID: PMC6827382 DOI: 10.1534/genetics.119.302679] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 09/04/2019] [Indexed: 02/07/2023] Open
Abstract
In meiosis, multiple different DNA sequence motifs help to position homologous recombination at hotspots in the genome. How do the seemingly disparate cis-acting regulatory modules each promote locally the activity of the basal recombination machinery? We defined molecular mechanisms of action for five different hotspot-activating DNA motifs (M26, CCAAT, Oligo-C, 4095, 4156) located independently at the same site within the ade6 locus of the fission yeast Schizosaccharomyces pombe Each motif promoted meiotic recombination (i.e., is active) within this context, and this activity required the respective binding proteins (transcription factors Atf1, Pcr1, Php2, Php3, Php5, Rst2). High-resolution analyses of chromatin structure by nucleosome scanning assays revealed that each motif triggers the displacement of nucleosomes surrounding the hotspot motif in meiosis. This chromatin remodeling required the respective sequence-specific binding proteins, was constitutive for two motifs, and was enhanced meiotically for three others. Hotspot activity of each motif strongly required the ATP-dependent chromatin remodeling enzyme Snf22 (Snf2/Swi2), with lesser dependence on Gcn5, Mst2, and Hrp3. These findings support a model in which most meiotic recombination hotspots are positioned by the binding of transcription factors to their respective DNA sites. The functional redundancy of multiple, sequence-specific protein-DNA complexes converges upon shared chromatin remodeling pathways that help provide the basal recombination machinery (Spo11/Rec12 complex) access to its DNA substrates within chromatin.
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Affiliation(s)
- Tresor O Mukiza
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Reine U Protacio
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Mari K Davidson
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Walter W Steiner
- Department of Biology, Niagara University, Lewiston, New York 14109
| | - Wayne P Wahls
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
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26
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Chereji RV, Bryson TD, Henikoff S. Quantitative MNase-seq accurately maps nucleosome occupancy levels. Genome Biol 2019; 20:198. [PMID: 31519205 PMCID: PMC6743174 DOI: 10.1186/s13059-019-1815-z] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 09/04/2019] [Indexed: 12/15/2022] Open
Abstract
Micrococcal nuclease (MNase) is widely used to map nucleosomes. However, its aggressive endo-/exo-nuclease activities make MNase-seq unreliable for determining nucleosome occupancies, because cleavages within linker regions produce oligo- and mono-nucleosomes, whereas cleavages within nucleosomes destroy them. Here, we introduce a theoretical framework for predicting nucleosome occupancies and an experimental protocol with appropriate spike-in normalization that confirms our theory and provides accurate occupancy levels over an MNase digestion time course. As with human cells, we observe no overall differences in nucleosome occupancies between Drosophila euchromatin and heterochromatin, which implies that heterochromatic compaction does not reduce MNase accessibility of linker DNA.
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Affiliation(s)
- Răzvan V Chereji
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Terri D Bryson
- Howard Hughes Medical Institute and Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute and Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA.
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27
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Chereji RV, Eriksson PR, Ocampo J, Prajapati HK, Clark DJ. Accessibility of promoter DNA is not the primary determinant of chromatin-mediated gene regulation. Genome Res 2019; 29:1985-1995. [PMID: 31511305 PMCID: PMC6886500 DOI: 10.1101/gr.249326.119] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 08/26/2019] [Indexed: 02/06/2023]
Abstract
DNA accessibility is thought to be of major importance in regulating gene expression. We test this hypothesis using a restriction enzyme as a probe of chromatin structure and as a proxy for transcription factors. We measured the digestion rate and the fraction of accessible DNA at almost all genomic AluI sites in budding yeast and mouse liver nuclei. Hepatocyte DNA is more accessible than yeast DNA, consistent with longer linkers between nucleosomes, suggesting that nucleosome spacing is a major determinant of accessibility. DNA accessibility varies from cell to cell, such that essentially no sites are accessible or inaccessible in every cell. AluI sites in inactive mouse promoters are accessible in some cells, implying that transcription factors could bind without activating the gene. Euchromatin and heterochromatin have very similar accessibilities, suggesting that transcription factors can penetrate heterochromatin. Thus, DNA accessibility is not likely to be the primary determinant of gene regulation.
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Affiliation(s)
- Răzvan V Chereji
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Peter R Eriksson
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Josefina Ocampo
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Hemant K Prajapati
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - David J Clark
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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28
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Abstract
Biochemical reactions are intrinsically stochastic, leading to variation in the production of mRNAs and proteins within cells. In the scientific literature, this source of variation is typically referred to as 'noise'. The observed variability in molecular phenotypes arises from a combination of processes that amplify and attenuate noise. Our ability to quantify cell-to-cell variability in numerous biological contexts has been revolutionized by recent advances in single-cell technology, from imaging approaches through to 'omics' strategies. However, defining, accurately measuring and disentangling the stochastic and deterministic components of cell-to-cell variability is challenging. In this Review, we discuss the sources, impact and function of molecular phenotypic variability and highlight future directions to understand its role.
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Affiliation(s)
- Nils Eling
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, UK.
- Wellcome Sanger Institute, Welcome Genome Campus, Hinxton, UK.
| | | | - John C Marioni
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, UK.
- Wellcome Sanger Institute, Welcome Genome Campus, Hinxton, UK.
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK.
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29
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Abstract
DNA is packaged into chromosomes, which are further organized into domains: Regions of the genome which are more likely to self-interact. Domains have been observed in species ranging from bacteria to humans and are thought to play an important role in gene regulation. Yet the mechanisms of domain formation are not fully understood. Here we use computer simulations to investigate domain formation in yeast. Our model reproduces the experimentally observed domains using only nucleosome positioning information as an input, implying that (unlike in higher eukaryotes) domain boundary locations are largely determined at this level. Our results reveal how irregular nucleosome spacing impacts the 3D chromosome organization, pointing to a direct link between nucleosome positioning and genome regulation at the large scale. We use molecular dynamics simulations based on publicly available micrococcal nuclease sequencing data for nucleosome positions to predict the 3D structure of chromatin in the yeast genome. Our main aim is to shed light on the mechanism underlying the formation of chromosomal interaction domains, chromosome regions of around 0.5 to 10 kbp which show enriched self-interactions, which were experimentally observed in recent MicroC experiments (importantly these are at a different length scale from the 100- to 1,000-kbp–sized domains observed in higher eukaryotes). We show that the sole input of nucleosome positioning data is already sufficient to determine the patterns of chromatin interactions and domain boundaries seen experimentally to a high degree of accuracy. Since the nucleosome spacing so strongly affects the larger-scale domain structure, we next examine the genome-wide linker-length distribution in more detail, finding that it is highly irregular and varies in different genomic regions such as gene bodies, promoters, and active and inactive genes. Finally we use our simple simulation model to characterize in more detail how irregular nucleosome spacing may affect local chromatin structure.
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30
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Bennett RL, Bele A, Small EC, Will CM, Nabet B, Oyer JA, Huang X, Ghosh RP, Grzybowski AT, Yu T, Zhang Q, Riva A, Lele TP, Schatz GC, Kelleher NL, Ruthenburg AJ, Liphardt J, Licht JD. A Mutation in Histone H2B Represents a New Class of Oncogenic Driver. Cancer Discov 2019; 9:1438-1451. [PMID: 31337617 DOI: 10.1158/2159-8290.cd-19-0393] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/24/2019] [Accepted: 07/18/2019] [Indexed: 12/30/2022]
Abstract
By examination of the cancer genomics database, we identified a new set of mutations in core histones that frequently recur in cancer patient samples and are predicted to disrupt nucleosome stability. In support of this idea, we characterized a glutamate to lysine mutation of histone H2B at amino acid 76 (H2B-E76K), found particularly in bladder and head and neck cancers, that disrupts the interaction between H2B and H4. Although H2B-E76K forms dimers with H2A, it does not form stable histone octamers with H3 and H4 in vitro, and when reconstituted with DNA forms unstable nucleosomes with increased sensitivity to nuclease. Expression of the equivalent H2B mutant in yeast restricted growth at high temperature and led to defective nucleosome-mediated gene repression. Significantly, H2B-E76K expression in the normal mammary epithelial cell line MCF10A increased cellular proliferation, cooperated with mutant PIK3CA to promote colony formation, and caused a significant drift in gene expression and fundamental changes in chromatin accessibility, particularly at gene regulatory elements. Taken together, these data demonstrate that mutations in the globular domains of core histones may give rise to an oncogenic program due to nucleosome dysfunction and deregulation of gene expression. SIGNIFICANCE: Mutations in the core histones frequently occur in cancer and represent a new mechanism of epigenetic dysfunction that involves destabilization of the nucleosome, deregulation of chromatin accessibility, and alteration of gene expression to drive cellular transformation.See related commentary by Sarthy and Henikoff, p. 1346.This article is highlighted in the In This Issue feature, p. 1325.
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Affiliation(s)
- Richard L Bennett
- Division of Hematology/Oncology, University of Florida Health Cancer Center, Gainesville, Florida
| | - Aditya Bele
- Division of Hematology/Oncology, University of Florida Health Cancer Center, Gainesville, Florida
| | - Eliza C Small
- Division of Hematology/Oncology, Northwestern University, Evanston, Illinois
| | - Christine M Will
- Division of Hematology/Oncology, Northwestern University, Evanston, Illinois
| | - Behnam Nabet
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts
| | - Jon A Oyer
- Division of Hematology/Oncology, Northwestern University, Evanston, Illinois
| | - Xiaoxiao Huang
- Division of Hematology/Oncology, University of Florida Health Cancer Center, Gainesville, Florida.,Department of Chemistry, Northwestern University, Evanston, Illinois
| | - Rajarshi P Ghosh
- Department of Bioengineering, Stanford University, Stanford, California
| | - Adrian T Grzybowski
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois
| | - Tao Yu
- Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee
| | - Qiao Zhang
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Alberto Riva
- Bioinformatics Core, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida
| | - Tanmay P Lele
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - George C Schatz
- Department of Chemistry, Northwestern University, Evanston, Illinois
| | - Neil L Kelleher
- Department of Chemistry, Northwestern University, Evanston, Illinois
| | - Alexander J Ruthenburg
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois
| | - Jan Liphardt
- Department of Bioengineering, Stanford University, Stanford, California
| | - Jonathan D Licht
- Division of Hematology/Oncology, University of Florida Health Cancer Center, Gainesville, Florida.
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31
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Wang Y, Wang A, Liu Z, Thurman AL, Powers LS, Zou M, Zhao Y, Hefel A, Li Y, Zabner J, Au KF. Single-molecule long-read sequencing reveals the chromatin basis of gene expression. Genome Res 2019; 29:1329-1342. [PMID: 31201211 PMCID: PMC6673713 DOI: 10.1101/gr.251116.119] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 06/10/2019] [Indexed: 11/25/2022]
Abstract
Genome-wide chromatin accessibility and nucleosome occupancy profiles have been widely investigated, while the long-range dynamics remain poorly studied at the single-cell level. Here, we present a new experimental approach, methyltransferase treatment followed by single-molecule long-read sequencing (MeSMLR-seq), for long-range mapping of nucleosomes and chromatin accessibility at single DNA molecules and thus achieve comprehensive-coverage characterization of the corresponding heterogeneity. MeSMLR-seq offers direct measurements of both nucleosome-occupied and nucleosome-evicted regions on a single DNA molecule, which is challenging for many existing methods. We applied MeSMLR-seq to haploid yeast, where single DNA molecules represent single cells, and thus we could investigate the combinatorics of many (up to 356) nucleosomes at long range in single cells. We illustrated the differential organization principles of nucleosomes surrounding the transcription start site for silent and actively transcribed genes, at the single-cell level and in the long-range scale. The heterogeneous patterns of chromatin status spanning multiple genes were phased. Together with single-cell RNA-seq data, we quantitatively revealed how chromatin accessibility correlated with gene transcription positively in a highly heterogeneous scenario. Moreover, we quantified the openness of promoters and investigated the coupled chromatin changes of adjacent genes at single DNA molecules during transcription reprogramming. In addition, we revealed the coupled changes of chromatin accessibility for two neighboring glucose transporter genes in response to changes in glucose concentration.
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Affiliation(s)
- Yunhao Wang
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, USA.,Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Anqi Wang
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, USA.,Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Zujun Liu
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, USA.,Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Andrew L Thurman
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Linda S Powers
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Meng Zou
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Yue Zhao
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, USA.,Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Adam Hefel
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Yunyi Li
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Joseph Zabner
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
| | - Kin Fai Au
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, USA.,Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA.,Department of Biostatistics, University of Iowa, Iowa City, Iowa 52242, USA
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32
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de Jong TV, Moshkin YM, Guryev V. Gene expression variability: the other dimension in transcriptome analysis. Physiol Genomics 2019; 51:145-158. [DOI: 10.1152/physiolgenomics.00128.2018] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transcriptome sequencing is a powerful technique to study molecular changes that underlie the differences in physiological conditions and disease progression. A typical question that is posed in such studies is finding genes with significant changes between sample groups. In this respect expression variability is regarded as a nuisance factor that is primarily of technical origin and complicates the data analysis. However, it is becoming apparent that the biological variation in gene expression might be an important molecular phenotype that can affect physiological parameters. In this review we explore the recent literature on technical and biological variability in gene expression, sources of expression variability, (epi-)genetic hallmarks, and evolutionary constraints in genes with robust and variable gene expression. We provide an overview of recent findings on effects of external cues, such as diet and aging, on expression variability and on other biological phenomena that can be linked to it. We discuss metrics and tools that were developed for quantification of expression variability and highlight the importance of future studies in this direction. To assist the adoption of expression variability analysis, we also provide a detailed description and computer code, which can easily be utilized by other researchers. We also provide a reanalysis of recently published data to highlight the value of the analysis method.
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Affiliation(s)
- Tristan V. de Jong
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Yuri M. Moshkin
- Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, Russia
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, Russia
| | - Victor Guryev
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
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33
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Nucleosome positioning and spacing: from genome-wide maps to single arrays. Essays Biochem 2019; 63:5-14. [PMID: 31015380 DOI: 10.1042/ebc20180058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/07/2019] [Accepted: 02/11/2019] [Indexed: 01/07/2023]
Abstract
The positioning of nucleosomes relative to DNA and their neighboring nucleosomes represents a fundamental layer of chromatin organization. Changes in nucleosome positioning and spacing affect the accessibility of DNA to regulatory factors and the formation of higher order chromatin structures. Sequencing of mononucleosomal fragments allowed mapping nucleosome positions on a genome-wide level in many organisms. This revealed that successions of evenly spaced and well-positioned nucleosomes-so called phased nucleosome arrays-occur at the 5' end of many active genes and in the vicinity of transcription factor and other protein binding sites. Phased arrays arise from the interplay of barrier elements on the DNA, which position adjacent nucleosomes, and the nucleosome spacing activity of ATP-dependent chromatin remodelers. A shortcoming of classic mononucleosomal mapping experiments is that they only reveal nucleosome spacing and array regularity at select sites in the genome with well-positioned nucleosomes. However, new technological approaches elucidate nucleosome array structure throughout the genome and with single-cell resolution. In the future, it will be interesting to see whether changes in nucleosome array regularity and spacing contribute to the formation of higher order chromatin structures and the spatial organization of the genome in vivo.
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34
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Ivanov M, Chernenko P, Breder V, Laktionov K, Rozhavskaya E, Musienko S, Baranova A, Mileyko V. Utility of cfDNA Fragmentation Patterns in Designing the Liquid Biopsy Profiling Panels to Improve Their Sensitivity. Front Genet 2019; 10:194. [PMID: 30915108 PMCID: PMC6422983 DOI: 10.3389/fgene.2019.00194] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/25/2019] [Indexed: 01/05/2023] Open
Abstract
Genotyping of cell-free DNA (cfDNA) in plasma samples has the potential to allow for a noninvasive assessment of tumor biology, avoiding the inherent shortcomings of tissue biopsy. Next generation sequencing (NGS), a leading technology for liquid biopsy analysis, continues to be hurdled with several major issues with cfDNA samples, including low cfDNA concentration and high fragmentation. In this study, by employing Ion Torrent PGM semiconductor technology, we performed a comparison between two multi-biomarker amplicon-based NGS panels characterized by a substantial difference in average amplicon length. In course of the analysis of the peripheral blood from 13 diagnostic non-small cell lung cancer patients, equivalence of two panels, in terms of overall diagnostic sensitivity and specificity was shown. A pairwise comparison of the allele frequencies for the same somatic variants obtained from the pairs of panel-specific amplicons, demonstrated an identical analytical sensitivity in range of 140 to 170 bp amplicons in size. Further regression analysis between amplicon length and its coverage, illustrated that NGS sequencing of plasma cfDNA equally tolerates amplicons with lengths in the range of 120 to 170 bp. To increase the sensitivity of mutation detection in cfDNA, we performed a computational analysis of the features associated with genome-wide nucleosome maps, evident from the data on the prevalence of cfDNA fragments of certain sizes and their fragmentation patterns. By leveraging the support vector machine-based machine learning approach, we showed that a combination of nucleosome map associated features with GC content, results in the increased accuracy of prediction of high inter-sample sequencing coverage variation (areas under the receiver operating curve: 0.75, 95% CI: 0.750–0.752 vs. 0.65, 95% CI: 0.63–0.67). Thus, nucleosome-guided fragmentation should be utilized as a guide to design amplicon-based NGS panels for the genotyping of cfDNA samples.
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Affiliation(s)
- Maxim Ivanov
- Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | | | - Valery Breder
- N.N. Blokhin Russian Cancer Research Center, Moscow, Russia
| | | | - Ekaterina Rozhavskaya
- Atlas Oncology Diagnostics, Ltd., Moscow, Russia.,Vavilov Institute of General Genetics, Moscow, Russia
| | | | - Ancha Baranova
- Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia.,Atlas Oncology Diagnostics, Ltd., Moscow, Russia.,Research Centre for Medical Genetics, Moscow, Russia.,School of Systems Biology, George Mason University, Fairfax, VA, United States
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35
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Xu Y, Lee JH, Li Z, Wang L, Ordog T, Bailey RC. A droplet microfluidic platform for efficient enzymatic chromatin digestion enables robust determination of nucleosome positioning. LAB ON A CHIP 2018; 18:2583-2592. [PMID: 30046796 PMCID: PMC6103843 DOI: 10.1039/c8lc00599k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The first step in chromatin-based epigenetic assays involves the fragmentation of chromatin to facilitate precise genomic localization of the associated DNA. Here, we report the development of a droplet microfluidic device that can rapidly and efficiently digest chromatin into single nucleosomes starting from whole-cell input material offering simplified and automated processing compared to conventional manual preparation. We demonstrate the digestion of chromatin from 2500-125 000 Jurkat cells using micrococcal nuclease for enzymatic processing. We show that the yield of mononucleosomal DNA can be optimized by controlling enzyme concentration and incubation time, with resulting mononucleosome yields exceeding 80%. Bioinformatic analysis of sequenced mononucleosomal DNA (MNase-seq) indicated a high degree of reproducibility and concordance (97-99%) compared with conventionally processed preparations. Our results demonstrate the feasibility of robust and automated nucleosome preparation using a droplet microfluidic platform for nucleosome positioning and downstream epigenomic assays.
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Affiliation(s)
- Yi Xu
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA.
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36
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Shan X, Roberts C, Lan Y, Percec I. Age Alters Chromatin Structure and Expression of SUMO Proteins under Stress Conditions in Human Adipose-Derived Stem Cells. Sci Rep 2018; 8:11502. [PMID: 30065345 PMCID: PMC6068198 DOI: 10.1038/s41598-018-29775-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/14/2018] [Indexed: 12/19/2022] Open
Abstract
Adult stem cells play a critical role in tissue homeostasis and repair. Aging leads to a decline in stem cells’ regenerative capacity that contributes significantly to the maintenance of organ and tissue functions. Age-dependent genomic and epigenetic modifications together play a role in the disruption of critical cellular pathways. However, the epigenetic mechanisms responsible for the decline of adult stem cell functions remain to be well established. Here, we investigated age-dependent, genome-wide alterations in the chromatin accessibility of primary human adipose-derived stem cells (ASCs) in comparison to age-matched fibroblasts via ATAC-seq technology. Our results demonstrate that aging ASCs possess globally more stable chromatin accessibility profiles as compared to aging fibroblasts, suggesting that robust regulatory mechanisms maintain adult stem cell chromatin structure against aging. Furthermore, we observed age-dependent subtle changes in promoter nucleosome positioning in selective pathways during aging, concurrent with altered small ubiquitin-related modifier (SUMO) protein expression under stress conditions. Together, our data suggest a significant role for nucleosome positioning in sumoylation pathway regulation in stress response during adult stem cell aging. The differences described here between the chromatin structure of human ASCs and fibroblasts will further elucidate the mechanisms regulating gene expression during aging in both stem cells and differentiated cells.
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Affiliation(s)
- Xiaoyin Shan
- Department of Surgery, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Cleresa Roberts
- Department of Surgery, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yemin Lan
- Epigenetics Institute, Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ivona Percec
- Department of Surgery, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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37
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Nicolas D, Zoller B, Suter DM, Naef F. Modulation of transcriptional burst frequency by histone acetylation. Proc Natl Acad Sci U S A 2018; 115:7153-7158. [PMID: 29915087 PMCID: PMC6142243 DOI: 10.1073/pnas.1722330115] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Many mammalian genes are transcribed during short bursts of variable frequencies and sizes that substantially contribute to cell-to-cell variability. However, which molecular mechanisms determine bursting properties remains unclear. To probe putative mechanisms, we combined temporal analysis of transcription along the circadian cycle with multiple genomic reporter integrations, using both short-lived luciferase live microscopy and single-molecule RNA-FISH. Using the Bmal1 circadian promoter as our model, we observed that rhythmic transcription resulted predominantly from variations in burst frequency, while the genomic position changed the burst size. Thus, burst frequency and size independently modulated Bmal1 transcription. We then found that promoter histone-acetylation level covaried with burst frequency, being greatest at peak expression and lowest at trough expression, while remaining unaffected by the genomic location. In addition, specific deletions of ROR-responsive elements led to constitutively elevated histone acetylation and burst frequency. We then investigated the suggested link between histone acetylation and burst frequency by dCas9p300-targeted modulation of histone acetylation, revealing that acetylation levels influence burst frequency more than burst size. The correlation between acetylation levels at the promoter and burst frequency was also observed in endogenous circadian genes and in embryonic stem cell fate genes. Thus, our data suggest that histone acetylation-mediated control of transcription burst frequency is a common mechanism to control mammalian gene expression.
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Affiliation(s)
- Damien Nicolas
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Benjamin Zoller
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - David M Suter
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Felix Naef
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
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38
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Zoli M. End-to-end distance and contour length distribution functions of DNA helices. J Chem Phys 2018; 148:214902. [DOI: 10.1063/1.5021639] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Marco Zoli
- School of Science and Technology, University of Camerino, I-62032 Camerino, Italy
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39
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Bameta T, Das D, Padinhateeri R. Coupling of replisome movement with nucleosome dynamics can contribute to the parent-daughter information transfer. Nucleic Acids Res 2018; 46:4991-5000. [PMID: 29850895 PMCID: PMC6007630 DOI: 10.1093/nar/gky207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 03/09/2018] [Indexed: 01/09/2023] Open
Abstract
Positioning of nucleosomes along the genomic DNA is crucial for many cellular processes that include gene regulation and higher order packaging of chromatin. The question of how nucleosome-positioning information from a parent chromatin gets transferred to the daughter chromatin is highly intriguing. Accounting for experimentally known coupling between replisome movement and nucleosome dynamics, we propose a model that can obtain de novo nucleosome assembly similar to what is observed in recent experiments. Simulating nucleosome dynamics during replication, we argue that short pausing of the replication fork, associated with nucleosome disassembly, can be a event crucial for communicating nucleosome positioning information from parent to daughter. We show that the interplay of timescales between nucleosome disassembly (τp) at the replication fork and nucleosome sliding behind the fork (τs) can give rise to a rich ‘phase diagram’ having different inherited patterns of nucleosome organization. Our model predicts that only when τp ≥ τs the daughter chromatin can inherit nucleosome positioning of the parent.
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Affiliation(s)
- Tripti Bameta
- UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Vidhyanagari Campus, Mumbai 400098, India
- To whom correspondence should be addressed. Tel: +91 22 25767761; Fax: +91 22 25767760; . Correspondence may also be addressed to Tripti Bameta.
| | - Dibyendu Das
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
- To whom correspondence should be addressed. Tel: +91 22 25767761; Fax: +91 22 25767760; . Correspondence may also be addressed to Tripti Bameta.
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40
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Nicolas D, Phillips NE, Naef F. What shapes eukaryotic transcriptional bursting? MOLECULAR BIOSYSTEMS 2018; 13:1280-1290. [PMID: 28573295 DOI: 10.1039/c7mb00154a] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Isogenic cells in a common environment present a large degree of heterogeneity in gene expression. Part of this variability is attributed to transcriptional bursting: the stochastic activation and inactivation of promoters that leads to the discontinuous production of mRNA. The diversity in bursting patterns displayed by different genes suggests the existence of a connection between bursting and gene regulation. Experimental strategies such as single-molecule RNA FISH, MS2-GFP or short-lived protein reporters allow the quantification of transcriptional bursting and the comparison of bursting kinetics between conditions, allowing therefore the identification of molecular mechanisms modulating transcriptional bursting. In this review we recapitulate the impact on transcriptional bursting of different molecular aspects of transcription such as the chromatin environment, nucleosome occupancy, histone modifications, the number and affinity of regulatory elements, DNA looping and transcription factor availability. More specifically, we examine their role in tuning the burst size or the burst frequency. While some molecular mechanisms involved in transcription such as histone marks can affect every aspect of bursting, others predominantly influence the burst size (e.g. the number and affinity of cis-regulatory elements) or frequency (e.g. transcription factor availability).
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Affiliation(s)
- Damien Nicolas
- The Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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41
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Chereji RV, Ramachandran S, Bryson TD, Henikoff S. Precise genome-wide mapping of single nucleosomes and linkers in vivo. Genome Biol 2018; 19:19. [PMID: 29426353 PMCID: PMC5807854 DOI: 10.1186/s13059-018-1398-0] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 01/24/2018] [Indexed: 11/10/2022] Open
Abstract
We developed a chemical cleavage method that releases single nucleosome dyad-containing fragments, allowing us to precisely map both single nucleosomes and linkers with high accuracy genome-wide in yeast. Our single nucleosome positioning data reveal that nucleosomes occupy preferred positions that differ by integral multiples of the DNA helical repeat. By comparing nucleosome dyad positioning maps to existing genomic and transcriptomic data, we evaluated the contributions of sequence, transcription, and histones H1 and H2A.Z in defining the chromatin landscape. We present a biophysical model that neglects DNA sequence and shows that steric occlusion suffices to explain the salient features of nucleosome positioning.
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Affiliation(s)
- Răzvan V Chereji
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Srinivas Ramachandran
- Howard Hughes Medical Institute and Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Terri D Bryson
- Howard Hughes Medical Institute and Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute and Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA.
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42
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Zhang Q, Oh DH, DiTusa SF, RamanaRao MV, Baisakh N, Dassanayake M, Smith AP. Rice nucleosome patterns undergo remodeling coincident with stress-induced gene expression. BMC Genomics 2018; 19:97. [PMID: 29373953 PMCID: PMC5787291 DOI: 10.1186/s12864-017-4397-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 12/19/2017] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Formation of nucleosomes along eukaryotic DNA has an impact on transcription. Major transcriptional changes occur in response to low external phosphate (Pi) in plants, but the involvement of chromatin-level mechanisms in Pi starvation responses have not been investigated. RESULTS We mapped nucleosomes along with transcriptional changes after 24-h of Pi starvation in rice (Oryza sativa) by deep sequencing of micrococcal nuclease digested chromatin and ribosome-depleted RNA. We demonstrated that nucleosome patterns at rice genes were affected by both cis- and trans-determinants, including GC content and transcription. Also, categorizing rice genes by nucleosome patterns across the transcription start site (TSS) revealed nucleosome patterns that correlated with distinct functional categories of genes. We further demonstrated that Pi starvation resulted in numerous dynamic nucleosomes, which were enhanced at genes differentially expressed in response to Pi starvation. CONCLUSIONS We demonstrate that rice nucleosome patterns are suggestive of gene functions, and reveal a link between chromatin remodeling and transcriptional changes in response to deficiency of a major macronutrient. Our findings help to enhance the understanding towards eukaryotic gene regulation at the chromatin level.
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Affiliation(s)
- Qi Zhang
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Dong-Ha Oh
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Sandra Feuer DiTusa
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Mangu V RamanaRao
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA
| | - Niranjan Baisakh
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA
| | - Maheshi Dassanayake
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Aaron P Smith
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
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43
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Barnett Burns S, Almeida D, Turecki G. The Epigenetics of Early Life Adversity: Current Limitations and Possible Solutions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 157:343-425. [DOI: 10.1016/bs.pmbts.2018.01.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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44
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Hermans N, Huisman JJ, Brouwer TB, Schächner C, van Heusden GPH, Griesenbeck J, van Noort J. Toehold-enhanced LNA probes for selective pull down and single-molecule analysis of native chromatin. Sci Rep 2017; 7:16721. [PMID: 29196662 PMCID: PMC5711847 DOI: 10.1038/s41598-017-16864-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 11/19/2017] [Indexed: 12/18/2022] Open
Abstract
The organization of DNA into chromatin is thought to regulate gene expression in eukaryotes. To study its structure in vitro, there is a need for techniques that can isolate specific chromosomal loci of natively assembled chromatin. Current purification methods often involve chemical cross-linking to preserve the chromatin composition. However, such cross-linking may affect the native structure. It also impedes single molecule force spectroscopy experiments, which have been instrumental to probe chromatin folding. Here we present a method for the incorporation of affinity tags, such as biotin, into native nucleoprotein fragments based on their DNA sequence, and subsequent single molecule analysis by magnetic tweezers. DNA oligos with several Locked Nucleic Acid (LNA) nucleotides are shown to selectively bind to target DNA at room temperature, mediated by a toehold end in the target, allowing for selective purification of DNA fragments. The stability of the probe-target hybrid is sufficient to withstand over 65 pN of force. We employ these probes to obtain force-extension curves of native chromatin fragments of the 18S ribosomal DNA from the yeast Saccharomyces cerevisiae. These experiments yield valuable insights in the heterogeneity in structure and composition of natively assembled chromatin at the single-molecule level.
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Affiliation(s)
- Nicolaas Hermans
- Leiden Institute of Physics, Huygens-Kamerlingh Onnes Laboratory, Niels Bohrweg, 2 2333 CA, Leiden, The Netherlands
| | - Juriën Jori Huisman
- Leiden Institute of Physics, Huygens-Kamerlingh Onnes Laboratory, Niels Bohrweg, 2 2333 CA, Leiden, The Netherlands
| | - Thomas Bauke Brouwer
- Leiden Institute of Physics, Huygens-Kamerlingh Onnes Laboratory, Niels Bohrweg, 2 2333 CA, Leiden, The Netherlands
| | - Christopher Schächner
- Universität Regensburg, Biochemie-Zentrum Regensburg (BZR), Institut für Biochemie, Genetik und Mikrobiologie, Lehrstuhl Biochemie III, 93053, Regensburg, Germany
| | - G Paul H van Heusden
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Joachim Griesenbeck
- Universität Regensburg, Biochemie-Zentrum Regensburg (BZR), Institut für Biochemie, Genetik und Mikrobiologie, Lehrstuhl Biochemie III, 93053, Regensburg, Germany
| | - John van Noort
- Leiden Institute of Physics, Huygens-Kamerlingh Onnes Laboratory, Niels Bohrweg, 2 2333 CA, Leiden, The Netherlands.
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45
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Resetting the Yeast Epigenome with Human Nucleosomes. Cell 2017; 171:1508-1519.e13. [PMID: 29198523 DOI: 10.1016/j.cell.2017.10.043] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/11/2017] [Accepted: 10/24/2017] [Indexed: 01/23/2023]
Abstract
Humans and yeast are separated by a billion years of evolution, yet their conserved histones retain central roles in gene regulation. Here, we "reset" yeast to use core human nucleosomes in lieu of their own (a rare event taking 20 days), which initially only worked with variant H3.1. The cells adapt by acquiring suppressor mutations in cell-division genes or by acquiring certain aneuploid states. Converting five histone residues to their yeast counterparts restored robust growth. We reveal that humanized nucleosomes are positioned according to endogenous yeast DNA sequence and chromatin-remodeling network, as judged by a yeast-like nucleosome repeat length. However, human nucleosomes have higher DNA occupancy, globally reduce RNA content, and slow adaptation to new conditions by delaying chromatin remodeling. These humanized yeasts (including H3.3) pose fundamental new questions about how chromatin is linked to many cell processes and provide a platform to study histone variants via yeast epigenome reprogramming.
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Bunina D, Štefl M, Huber F, Khmelinskii A, Meurer M, Barry JD, Kats I, Kirrmaier D, Huber W, Knop M. Upregulation of SPS100 gene expression by an antisense RNA via a switch of mRNA isoforms with different stabilities. Nucleic Acids Res 2017; 45:11144-11158. [PMID: 28977638 PMCID: PMC5737743 DOI: 10.1093/nar/gkx737] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/09/2017] [Accepted: 08/21/2017] [Indexed: 12/19/2022] Open
Abstract
Pervasive transcription of genomes generates multiple classes of non-coding RNAs. One of these classes are stable long non-coding RNAs which overlap coding genes in antisense direction (asRNAs). The function of such asRNAs is not fully understood but several cases of antisense-dependent gene expression regulation affecting the overlapping genes have been demonstrated. Using high-throughput yeast genetics and a limited set of four growth conditions we previously reported a regulatory function for ∼25% of asRNAs, most of which repress the expression of the sense gene. To further explore the roles of asRNAs we tested more conditions and identified 15 conditionally antisense-regulated genes, 6 of which exhibited antisense-dependent enhancement of gene expression. We focused on the sporulation-specific gene SPS100, which becomes upregulated upon entry into starvation or sporulation as a function of the antisense transcript SUT169. We demonstrate that the antisense effect is mediated by its 3' intergenic region (3'-IGR) and that this regulation can be transferred to other genes. Genetic analysis revealed that SUT169 functions by changing the relative expression of SPS100 mRNA isoforms from a short and unstable transcript to a long and stable species. These results suggest a novel mechanism of antisense-dependent gene regulation via mRNA isoform switching.
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Affiliation(s)
- Daria Bunina
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Martin Štefl
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Florian Huber
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Anton Khmelinskii
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Matthias Meurer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Joseph D. Barry
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Ilia Kats
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Daniel Kirrmaier
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
- Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Wolfgang Huber
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
- Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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Libault M, Pingault L, Zogli P, Schiefelbein J. Plant Systems Biology at the Single-Cell Level. TRENDS IN PLANT SCIENCE 2017; 22:949-960. [PMID: 28970001 DOI: 10.1016/j.tplants.2017.08.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 08/14/2017] [Accepted: 08/21/2017] [Indexed: 05/19/2023]
Abstract
Our understanding of plant biology is increasingly being built upon studies using 'omics and system biology approaches performed at the level of the entire plant, organ, or tissue. Although these approaches open new avenues to better understand plant biology, they suffer from the cellular complexity of the analyzed sample. Recent methodological advances now allow plant scientists to overcome this limitation and enable biological analyses of single-cells or single-cell-types. Coupled with the development of bioinformatics and functional genomics resources, these studies provide opportunities for high-resolution systems analyses of plant phenomena. In this review, we describe the recent advances, current challenges, and future directions in exploring the biology of single-cells and single-cell-types to enhance our understanding of plant biology as a system.
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Affiliation(s)
- Marc Libault
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA.
| | - Lise Pingault
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Prince Zogli
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - John Schiefelbein
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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Teunissen JHM, Crooijmans ME, Teunisse PPP, van Heusden GPH. Lack of 14-3-3 proteins in Saccharomyces cerevisiae results in cell-to-cell heterogeneity in the expression of Pho4-regulated genes SPL2 and PHO84. BMC Genomics 2017; 18:701. [PMID: 28877665 PMCID: PMC5588707 DOI: 10.1186/s12864-017-4105-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/31/2017] [Indexed: 01/16/2023] Open
Abstract
Background Ion homeostasis is an essential property of living organisms. The yeast Saccharomyces cerevisiae is an ideal model organism to investigate ion homeostasis at all levels. In this yeast genes involved in high-affinity phosphate uptake (PHO genes) are strongly induced during both phosphate and potassium starvation, indicating a link between phosphate and potassium homeostasis. However, the signal transduction processes involved are not completely understood. As 14-3-3 proteins are key regulators of signal transduction processes, we investigated the effect of deletion of the 14-3-3 genes BMH1 or BMH2 on gene expression during potassium starvation and focused especially on the expression of genes involved in phosphate uptake. Results Genome-wide analysis of the effect of disruption of either BMH1 or BMH2 revealed that the mRNA levels of the PHO genes PHO84 and SPL2 are greatly reduced in the mutant strains compared to the levels in wild type strains. This was especially apparent at standard potassium and phosphate concentrations. Furthermore the promoter of these genes is less active after deletion of BMH1. Microscopic and flow cytometric analysis of cells with GFP-tagged SPL2 showed that disruption of BMH1 resulted in two populations of genetically identical cells, cells expressing the protein and the majority of cells with no detectible expression. Heterogeneity was also observed for the expression of GFP under control of the PHO84 promoter. Upon deletion of PHO80 encoding a regulator of the transcription factor Pho4, the effect of the BMH1 deletion on SPL2 and PHO84 promoter was lost, suggesting that the BMH1 deletion mainly influences processes upstream of the Pho4 transcription factor. Conclusion Our data indicate that that yeast cells can be in either of two states, expressing or not expressing genes required for high-affinity phosphate uptake and that 14-3-3 proteins are involved in the process(es) that establish the activation state of the PHO regulon. Electronic supplementary material The online version of this article (10.1186/s12864-017-4105-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Janneke H M Teunissen
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands
| | - Marjolein E Crooijmans
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands
| | - Pepijn P P Teunisse
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands
| | - G Paul H van Heusden
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands.
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49
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SIRT6 regulated nucleosomal occupancy affects Hexokinase 2 expression. Exp Cell Res 2017; 357:98-106. [DOI: 10.1016/j.yexcr.2017.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/01/2017] [Accepted: 05/03/2017] [Indexed: 11/20/2022]
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50
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Tan H, Liu T, Zhang J, Zhou T. Random positioning of nucleosomes enhances heritable bistability. MOLECULAR BIOSYSTEMS 2017; 13:132-141. [PMID: 27833942 DOI: 10.1039/c6mb00729e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chromosomal regions are often dynamically modified by histones, leading to the uncertainty of nucleosome positions. Experiments have provided evidence for this randomness, but it is unclear how it impacts epigenetic heritability. Here, by analyzing a mechanic model at the molecular level, which considers three representative types of nucleosomes (unmodified, methylated, and acetylated) and dynamic nucleosome modifications, we find that in contrast to the equidistance partition of nucleosomes, random partition can significantly enhance heritable bistability. Moreover, the more "chaotic" the nucleosome positions are, the better the heritable bistability is, in contrast to the previous view. In both cases of nucleosome positioning, heritable bistability occurs only when the total nucleosome number is beyond a threshold, and it depends strongly on the allocation rate that enzymes regulate transitions between different nucleosome types. Thus, we conclude that random positioning of nucleosomes is an unneglectable factor impacting heritable bistability. A point worth mentioning is that our model established on a master equation can easily be extended to include other more complex processes underlying dynamic nucleosome modifications.
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Affiliation(s)
- Heli Tan
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China. and School of Mathematics and Computational Science, Xiangtan University, XiangTan 411105, P. R. China
| | - Tuoqi Liu
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
| | - Jiajun Zhang
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
| | - Tianshou Zhou
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
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