1
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Nie XY, Menet JS. Circadian regulation of stereotypic chromatin conformations at enhancers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.24.590818. [PMID: 38712031 PMCID: PMC11071494 DOI: 10.1101/2024.04.24.590818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Cooperation between the circadian transcription factor (TF) CLOCK:BMAL1 and other TFs at cis-regulatory elements (CREs) is critical to daily rhythms of transcription. Yet, the modalities of this cooperation are unclear. Here, we analyzed the co-binding of multiple TFs on single DNA molecules in mouse liver using single molecule footprinting (SMF). We found that SMF reads clustered in stereotypic chromatin states that reflect distinguishable organization of TFs and nucleosomes, and that were remarkably conserved between all samples. DNA protection at CLOCK:BMAL1 binding motif (E-box) varied between CREs, from E-boxes being solely bound by CLOCK:BMAL1 to situations where other TFs competed with CLOCK:BMAL1 for E-box binding. SMF also uncovered CLOCK:BMAL1 cooperative binding at E-boxes separated by 250 bp, which structurally altered the CLOCK:BMAL1-DNA interface. Importantly, we discovered multiple nucleosomes with E-boxes at entry/exit sites that were removed upon CLOCK:BMAL1 DNA binding, thereby promoting the formation of open chromatin states that facilitate DNA binding of other TFs and that were associated with rhythmic transcription. These results demonstrate the utility of SMF for studying how CLOCK:BMAL1 and other TFs regulate stereotypical chromatin states at CREs to promote transcription.
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Affiliation(s)
- Xinyu Y. Nie
- Department of Biology, Center for Biological Clock Research, Texas A&M University, College Station, TX
| | - Jerome S. Menet
- Department of Biology, Center for Biological Clock Research, Texas A&M University, College Station, TX
- Interdisciplinary Program of Genetics, Texas A&M University, College Station, TX
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2
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Eggers N, Gkountromichos F, Krause S, Campos-Sparr A, Becker P. Physical interaction between MSL2 and CLAMP assures direct cooperativity and prevents competition at composite binding sites. Nucleic Acids Res 2023; 51:9039-9054. [PMID: 37602401 PMCID: PMC10516644 DOI: 10.1093/nar/gkad680] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/13/2023] [Accepted: 08/09/2023] [Indexed: 08/22/2023] Open
Abstract
MSL2, the DNA-binding subunit of the Drosophila dosage compensation complex, cooperates with the ubiquitous protein CLAMP to bind MSL recognition elements (MREs) on the X chromosome. We explore the nature of the cooperative binding to these GA-rich, composite sequence elements in reconstituted naïve embryonic chromatin. We found that the cooperativity requires physical interaction between both proteins. Remarkably, disruption of this interaction does not lead to indirect, nucleosome-mediated cooperativity as expected, but to competition. The protein interaction apparently not only increases the affinity for composite binding sites, but also locks both proteins in a defined dimeric state that prevents competition. High Affinity Sites of MSL2 on the X chromosome contain variable numbers of MREs. We find that the cooperation between MSL2/CLAMP is not influenced by MRE clustering or arrangement, but happens largely at the level of individual MREs. The sites where MSL2/CLAMP bind strongly in vitro locate to all chromosomes and show little overlap to an expanded set of X-chromosomal MSL2 in vivo binding sites generated by CUT&RUN. Apparently, the intrinsic MSL2/CLAMP cooperativity is limited to a small selection of potential sites in vivo. This restriction must be due to components missing in our reconstitution, such as roX2 lncRNA.
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Affiliation(s)
- Nikolas Eggers
- Biomedical Center, Molecular Biology Division, LMU, Munich, Germany
| | | | - Silke Krause
- Biomedical Center, Molecular Biology Division, LMU, Munich, Germany
| | | | - Peter B Becker
- Biomedical Center, Molecular Biology Division, LMU, Munich, Germany
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3
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Losa M, Barozzi I, Osterwalder M, Hermosilla-Aguayo V, Morabito A, Chacón BH, Zarrineh P, Girdziusaite A, Benazet JD, Zhu J, Mackem S, Capellini TD, Dickel D, Bobola N, Zuniga A, Visel A, Zeller R, Selleri L. A spatio-temporally constrained gene regulatory network directed by PBX1/2 acquires limb patterning specificity via HAND2. Nat Commun 2023; 14:3993. [PMID: 37414772 PMCID: PMC10325989 DOI: 10.1038/s41467-023-39443-z] [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: 03/17/2022] [Accepted: 06/14/2023] [Indexed: 07/08/2023] Open
Abstract
A lingering question in developmental biology has centered on how transcription factors with widespread distribution in vertebrate embryos can perform tissue-specific functions. Here, using the murine hindlimb as a model, we investigate the elusive mechanisms whereby PBX TALE homeoproteins, viewed primarily as HOX cofactors, attain context-specific developmental roles despite ubiquitous presence in the embryo. We first demonstrate that mesenchymal-specific loss of PBX1/2 or the transcriptional regulator HAND2 generates similar limb phenotypes. By combining tissue-specific and temporally controlled mutagenesis with multi-omics approaches, we reconstruct a gene regulatory network (GRN) at organismal-level resolution that is collaboratively directed by PBX1/2 and HAND2 interactions in subsets of posterior hindlimb mesenchymal cells. Genome-wide profiling of PBX1 binding across multiple embryonic tissues further reveals that HAND2 interacts with subsets of PBX-bound regions to regulate limb-specific GRNs. Our research elucidates fundamental principles by which promiscuous transcription factors cooperate with cofactors that display domain-restricted localization to instruct tissue-specific developmental programs.
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Affiliation(s)
- Marta Losa
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Iros Barozzi
- Center for Cancer Research, Medical University of Vienna, Vienna, Austria
| | - Marco Osterwalder
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department for Biomedical Research (DBMR), University of Bern, Bern, Switzerland
- Department of Cardiology, Bern University Hospital, Bern, Switzerland
| | - Viviana Hermosilla-Aguayo
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Angela Morabito
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Brandon H Chacón
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Peyman Zarrineh
- School of Medical Sciences, University of Manchester, Manchester, UK
| | - Ausra Girdziusaite
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Jean Denis Benazet
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Jianjian Zhu
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Susan Mackem
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Terence D Capellini
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Diane Dickel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Nicoletta Bobola
- School of Medical Sciences, University of Manchester, Manchester, UK
| | - Aimée Zuniga
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Axel Visel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- School of Natural Sciences, University of California, Merced, Merced, CA, 95343, USA
| | - Rolf Zeller
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Licia Selleri
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA.
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4
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Michael AK, Stoos L, Crosby P, Eggers N, Nie XY, Makasheva K, Minnich M, Healy KL, Weiss J, Kempf G, Cavadini S, Kater L, Seebacher J, Vecchia L, Chakraborty D, Isbel L, Grand RS, Andersch F, Fribourgh JL, Schübeler D, Zuber J, Liu AC, Becker PB, Fierz B, Partch CL, Menet JS, Thomä NH. Cooperation between bHLH transcription factors and histones for DNA access. Nature 2023; 619:385-393. [PMID: 37407816 PMCID: PMC10338342 DOI: 10.1038/s41586-023-06282-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 06/02/2023] [Indexed: 07/07/2023]
Abstract
The basic helix-loop-helix (bHLH) family of transcription factors recognizes DNA motifs known as E-boxes (CANNTG) and includes 108 members1. Here we investigate how chromatinized E-boxes are engaged by two structurally diverse bHLH proteins: the proto-oncogene MYC-MAX and the circadian transcription factor CLOCK-BMAL1 (refs. 2,3). Both transcription factors bind to E-boxes preferentially near the nucleosomal entry-exit sites. Structural studies with engineered or native nucleosome sequences show that MYC-MAX or CLOCK-BMAL1 triggers the release of DNA from histones to gain access. Atop the H2A-H2B acidic patch4, the CLOCK-BMAL1 Per-Arnt-Sim (PAS) dimerization domains engage the histone octamer disc. Binding of tandem E-boxes5-7 at endogenous DNA sequences occurs through direct interactions between two CLOCK-BMAL1 protomers and histones and is important for circadian cycling. At internal E-boxes, the MYC-MAX leucine zipper can also interact with histones H2B and H3, and its binding is indirectly enhanced by OCT4 elsewhere on the nucleosome. The nucleosomal E-box position and the type of bHLH dimerization domain jointly determine the histone contact, the affinity and the degree of competition and cooperativity with other nucleosome-bound factors.
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Affiliation(s)
- Alicia K Michael
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Lisa Stoos
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Priya Crosby
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Nikolas Eggers
- Biomedical Center, Molecular Biology Division, Ludwig-Maximilians-Universität, Munich, Germany
| | - Xinyu Y Nie
- Department of Biology, Center for Biological Clock Research, Texas A&M University, College Station, TX, USA
| | - Kristina Makasheva
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Martina Minnich
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Kelly L Healy
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Joscha Weiss
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Georg Kempf
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Simone Cavadini
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Lukas Kater
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jan Seebacher
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Luca Vecchia
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Deyasini Chakraborty
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Luke Isbel
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Ralph S Grand
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Florian Andersch
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
| | - Jennifer L Fribourgh
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Dirk Schübeler
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Johannes Zuber
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna, Austria
- Medical University of Vienna, Vienna, Austria
| | - Andrew C Liu
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Peter B Becker
- Biomedical Center, Molecular Biology Division, Ludwig-Maximilians-Universität, Munich, Germany
| | - Beat Fierz
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Carrie L Partch
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Jerome S Menet
- Department of Biology, Center for Biological Clock Research, Texas A&M University, College Station, TX, USA
| | - Nicolas H Thomä
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
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5
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Xu M, Sun M, Zhang X, Nguyen R, Lei H, Shern JF, Thiele CJ, Liu Z. HAND2 Assists MYCN Enhancer Invasion to Regulate a Noradrenergic Neuroblastoma Phenotype. Cancer Res 2023; 83:686-699. [PMID: 36598365 PMCID: PMC10240397 DOI: 10.1158/0008-5472.can-22-2042] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 11/16/2022] [Accepted: 12/28/2022] [Indexed: 01/05/2023]
Abstract
Noradrenergic neuroblastoma is characterized by a core transcriptional regulatory circuitry (CRC) comprised of transcription factors (TF) such as PHOX2B, HAND2, and GATA3, which form a network with MYCN. At normal physiologic levels, MYCN mainly binds to promoters but when aberrantly upregulated as in neuroblastoma, MYCN also binds to enhancers. Here, we investigated how MYCN invades enhancers and whether CRC TFs play a role in this process. HAND2 was found to regulate chromatin accessibility and to assist MYCN binding to enhancers. Moreover, HAND2 cooperated with MYCN to compete with nucleosomes to regulate global gene transcription. The cooperative interaction between MYCN and HAND2 could be targeted with an Aurora A kinase inhibitor plus a histone deacetylase inhibitor, resulting in potent downregulation of both MYCN and the CRC TFs and suppression of MYCN-amplified neuroblastoma tumor growth. This study identifies cooperation between MYCN and HAND2 in neuroblastoma and demonstrates that simultaneously targeting MYCN and CRC TFs is an effective way to treat this aggressive pediatric tumor. SIGNIFICANCE HAND2 and MYCN compete with nucleosomes to regulate global gene transcription and to drive a malignant neuroblastoma phenotype.
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Affiliation(s)
- Man Xu
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
| | - Ming Sun
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
| | - Xiyuan Zhang
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
| | - Rosa Nguyen
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
| | - Haiyan Lei
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
| | - Jack F. Shern
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
| | - Carol J. Thiele
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
| | - Zhihui Liu
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA
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6
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Abstract
Genomic DNA wraps around core histones to form nucleosomes, which provides steric constraints on how transcription factors (TFs) can interact with gene regulatory sequences. It is increasingly apparent that well-positioned, accessible nucleosomes are an inherent feature of active enhancers and can facilitate cooperative TF binding, referred to as nucleosome-mediated cooperativity. Thus, profiling chromatin and nucleosome properties (accessibility, positioning, and occupancy) on the genome is crucial to understand cell-type-specific gene regulation. Here we describe a simplified protocol to profile accessible nucleosomes in the mammalian genome using low-level and high-level micrococcal nuclease (MNase) digestion followed by genome-wide sequencing.
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Affiliation(s)
- Hee-Woong Lim
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Makiko Iwafuchi
- Division of Developmental Biology, Center for Stem Cell & Organoid Medicine (CuSTOM), Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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7
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Yang MG, Ling E, Cowley CJ, Greenberg ME, Vierbuchen T. Characterization of sequence determinants of enhancer function using natural genetic variation. eLife 2022; 11:76500. [PMID: 36043696 PMCID: PMC9662815 DOI: 10.7554/elife.76500] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 08/30/2022] [Indexed: 02/04/2023] Open
Abstract
Sequence variation in enhancers that control cell-type-specific gene transcription contributes significantly to phenotypic variation within human populations. However, it remains difficult to predict precisely the effect of any given sequence variant on enhancer function due to the complexity of DNA sequence motifs that determine transcription factor (TF) binding to enhancers in their native genomic context. Using F1-hybrid cells derived from crosses between distantly related inbred strains of mice, we identified thousands of enhancers with allele-specific TF binding and/or activity. We find that genetic variants located within the central region of enhancers are most likely to alter TF binding and enhancer activity. We observe that the AP-1 family of TFs (Fos/Jun) are frequently required for binding of TEAD TFs and for enhancer function. However, many sequence variants outside of core motifs for AP-1 and TEAD also impact enhancer function, including sequences flanking core TF motifs and AP-1 half sites. Taken together, these data represent one of the most comprehensive assessments of allele-specific TF binding and enhancer function to date and reveal how sequence changes at enhancers alter their function across evolutionary timescales.
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Affiliation(s)
- Marty G Yang
- Department of Neurobiology, Harvard Medical School, Boston, United States.,Program in Neuroscience, Harvard Medical School, Boston, United States
| | - Emi Ling
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | | | | | - Thomas Vierbuchen
- Developmental Biology Program, Sloan Kettering Institute for Cancer Research, New York, United States.,Center for Stem Cell Biology, Sloan Kettering Institute for Cancer Research, New York, United States
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8
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Sanchez-Priego C, Hu R, Boshans LL, Lalli M, Janas JA, Williams SE, Dong Z, Yang N. Mapping cis-regulatory elements in human neurons links psychiatric disease heritability and activity-regulated transcriptional programs. Cell Rep 2022; 39:110877. [PMID: 35649373 PMCID: PMC9219592 DOI: 10.1016/j.celrep.2022.110877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 03/01/2022] [Accepted: 05/05/2022] [Indexed: 12/17/2022] Open
Abstract
Genome-wide association studies (GWASs) have identified hundreds of loci associated with psychiatric diseases, yet there is a lack of understanding of disease pathophysiology. Common risk variants can shed light on the underlying molecular mechanisms; however, identifying causal variants remains challenging. We map cis-regulatory elements in human neurons derived from pluripotent stem cells. This system allows us to determine enhancers that activate the transcription of neuronal activity-regulated gene programs, which are thought to be critical for synaptic plasticity and are not possible to identify from postmortem tissues. Using the activity-by-contact model, we create variant-to-gene maps to interpret the function of GWAS variants. Our work nominates a subset of variants to elucidate the molecular mechanisms involving GWAS-significant loci. It also highlights that in vitro human cellular models are a powerful platform for identifying and mechanistic studies of human trait-associated genetic variants in cell states that are inaccessible from other types of human samples.
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Affiliation(s)
- Carlos Sanchez-Priego
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Ruiqi Hu
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Linda L Boshans
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Matthew Lalli
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Justyna A Janas
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sarah E Williams
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Zhiqiang Dong
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China.
| | - Nan Yang
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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9
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Ahmad K, Henikoff S, Ramachandran S. Managing the Steady State Chromatin Landscape by Nucleosome Dynamics. Annu Rev Biochem 2022; 91:183-195. [PMID: 35303789 DOI: 10.1146/annurev-biochem-032620-104508] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Gene regulation arises out of dynamic competition between nucleosomes, transcription factors, and other chromatin proteins for the opportunity to bind genomic DNA. The timescales of nucleosome assembly and binding of factors to DNA determine the outcomes of this competition at any given locus. Here, we review how these properties of chromatin proteins and the interplay between the dynamics of different factors are critical for gene regulation. We discuss how molecular structures of large chromatin-associated complexes, kinetic measurements, and high resolution mapping of protein-DNA complexes in vivo set the boundary conditions for chromatin dynamics, leading to models of how the steady state behaviors of regulatory elements arise. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Kami Ahmad
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA;
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA; .,Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics and RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado, USA
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10
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Rao S, Ahmad K, Ramachandran S. Cooperative binding between distant transcription factors is a hallmark of active enhancers. Mol Cell 2021; 81:1651-1665.e4. [PMID: 33705711 DOI: 10.1016/j.molcel.2021.02.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/22/2022]
Abstract
Enhancers harbor binding motifs that recruit transcription factors (TFs) for gene activation. While cooperative binding of TFs at enhancers is known to be critical for transcriptional activation of a handful of developmental enhancers, the extent of TF cooperativity genome-wide is unknown. Here, we couple high-resolution nuclease footprinting with single-molecule methylation profiling to characterize TF cooperativity at active enhancers in the Drosophila genome. Enrichment of short micrococcal nuclease (MNase)-protected DNA segments indicates that the majority of enhancers harbor two or more TF-binding sites, and we uncover protected fragments that correspond to co-bound sites in thousands of enhancers. From the analysis of co-binding, we find that cooperativity dominates TF binding in vivo at the majority of active enhancers. Cooperativity is highest between sites spaced 50 bp apart, indicating that cooperativity occurs without apparent protein-protein interactions. Our findings suggest nucleosomes promoting cooperativity because co-binding may effectively clear nucleosomes and promote enhancer function.
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Affiliation(s)
- Satyanarayan Rao
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kami Ahmad
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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11
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Bridoux L, Zarrineh P, Mallen J, Phuycharoen M, Latorre V, Ladam F, Losa M, Baker SM, Sagerstrom C, Mace KA, Rattray M, Bobola N. HOX paralogs selectively convert binding of ubiquitous transcription factors into tissue-specific patterns of enhancer activation. PLoS Genet 2020; 16:e1009162. [PMID: 33315856 PMCID: PMC7769617 DOI: 10.1371/journal.pgen.1009162] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 12/28/2020] [Accepted: 09/28/2020] [Indexed: 11/18/2022] Open
Abstract
Gene expression programs determine cell fate in embryonic development and their dysregulation results in disease. Transcription factors (TFs) control gene expression by binding to enhancers, but how TFs select and activate their target enhancers is still unclear. HOX TFs share conserved homeodomains with highly similar sequence recognition properties, yet they impart the identity of different animal body parts. To understand how HOX TFs control their specific transcriptional programs in vivo, we compared HOXA2 and HOXA3 binding profiles in the mouse embryo. HOXA2 and HOXA3 directly cooperate with TALE TFs and selectively target different subsets of a broad TALE chromatin platform. Binding of HOX and tissue-specific TFs convert low affinity TALE binding into high confidence, tissue-specific binding events, which bear the mark of active enhancers. We propose that HOX paralogs, alone and in combination with tissue-specific TFs, generate tissue-specific transcriptional outputs by modulating the activity of TALE TFs at selected enhancers.
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Affiliation(s)
- Laure Bridoux
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Peyman Zarrineh
- School of Health Sciences, University of Manchester, Manchester, United Kingdom
| | - Joshua Mallen
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Mike Phuycharoen
- Department of Computer Science, University of Manchester, Manchester, United Kingdom
| | - Victor Latorre
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Frank Ladam
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusets, United States of America
| | - Marta Losa
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Syed Murtuza Baker
- School of Health Sciences, University of Manchester, Manchester, United Kingdom
- School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Charles Sagerstrom
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusets, United States of America
| | - Kimberly A. Mace
- School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Magnus Rattray
- School of Health Sciences, University of Manchester, Manchester, United Kingdom
| | - Nicoletta Bobola
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail:
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12
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Wang X, Cairns MJ, Yan J. Super-enhancers in transcriptional regulation and genome organization. Nucleic Acids Res 2020; 47:11481-11496. [PMID: 31724731 PMCID: PMC7145697 DOI: 10.1093/nar/gkz1038] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/19/2019] [Accepted: 10/22/2019] [Indexed: 12/14/2022] Open
Abstract
Gene expression is precisely controlled in a stage and cell-type-specific manner, largely through the interaction between cis-regulatory elements and their associated trans-acting factors. Where these components aggregate in promoters and enhancers, they are able to cooperate to modulate chromatin structure and support the engagement in long-range 3D superstructures that shape the dynamics of a cell's genomic architecture. Recently, the term 'super-enhancer' has been introduced to describe a hyper-active regulatory domain comprising a complex array of sequence elements that work together to control the key gene networks involved in cell identity. Here, we survey the unique characteristics of super-enhancers compared to other enhancer types and summarize the recent advances in our understanding of their biological role in gene regulation. In particular, we discuss their capacity to attract the formation of phase-separated condensates, and capacity to generate three-dimensional genome structures that precisely activate their target genes. We also propose a multi-stage transition model to explain the evolutionary pressure driving the development of super-enhancers in complex organisms, and highlight the potential for involvement in tumorigenesis. Finally, we discuss more broadly the role of super-enhancers in human health disorders and related potential in therapeutic interventions.
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Affiliation(s)
- Xi Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education / School of Life Sciences, Northwest University, Xi'an 710069, China.,Division of Theoretical Systems Biology, Germany Cancer Research Center, Heidelberg 69115, Germany.,School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia
| | - Murray J Cairns
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.,Centre for Brain and Mental Health Research, University of Newcastle, Callaghan, NSW 2308, Australia; and Hunter Medical Research Institute
| | - Jian Yan
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education / School of Life Sciences, Northwest University, Xi'an 710069, China.,Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong S.A.R., China
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13
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Ensembles of Breathing Nucleosomes: A Computational Study. Biophys J 2019; 118:2297-2308. [PMID: 31882248 DOI: 10.1016/j.bpj.2019.11.3395] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/15/2019] [Accepted: 11/25/2019] [Indexed: 12/13/2022] Open
Abstract
About three-fourths of the human DNA molecules are wrapped into nucleosomes, protein spools with DNA. Nucleosomes are highly dynamic, transiently exposing their DNA through spontaneous unspooling. Recent experiments allowed to observe the DNA of an ensemble of such breathing nucleosomes through x-ray diffraction with contrast matching between the solvent and the protein core. In this study, we calculate such an ensemble through a Monte Carlo simulation of a coarse-grained nucleosome model with sequence-dependent DNA mechanics. Our analysis gives detailed insights into the sequence dependence of nucleosome breathing observed in the experiment and allows us to determine the adsorption energy of the DNA bound to the protein core as a function of the ionic strength. Moreover, we predict the breathing behavior of other potentially interesting sequences and compare the findings to earlier related experiments.
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14
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Brehove M, Shatoff E, Donovan BT, Jipa CM, Bundschuh R, Poirier MG. DNA sequence influences hexasome orientation to regulate DNA accessibility. Nucleic Acids Res 2019; 47:5617-5633. [PMID: 31216039 PMCID: PMC6582347 DOI: 10.1093/nar/gkz283] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 04/03/2019] [Accepted: 04/20/2019] [Indexed: 02/02/2023] Open
Abstract
Nucleosomes, the fundamental organizing units of eukaryotic genomes, contain ∼146 base pairs of DNA wrapped around a histone H3–H4 tetramer and two histone H2A–H2B dimers. Converting nucleosomes into hexasomes by removal of a H2A–H2B dimer is an important regulatory event, but its regulation and functional consequences are not well-understood. To investigate the influence of hexasomes on DNA accessibility, we used the property of the Widom-601 Nucleosome Positioning Sequence (NPS) to form homogeneously oriented hexasomes in vitro. We find that DNA accessibility to transcription factors (TF) on the hexasome H2A–H2B distal side is identical to naked DNA, while the accessibility on the H2A–H2B proximal side is reduced by 2-fold, which is due to a 2-fold reduction in hexasome unwrapping probability. We then determined that a 23 bp region of the Widom-601 NPS is responsible for forming homogeneously oriented hexasomes. Analysis of published ChIP-exo data of hexasome containing genes identified two DNA sequence motifs that correlate with hexasome orientation in vivo, while ExoIII mapping studies of these sequences revealed they generate homogeneously oriented hexasomes in vitro. These results indicate that hexasome orientation, which is influenced by the underlying DNA sequence in vivo, is important for modulating DNA accessibility to regulate transcription.
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Affiliation(s)
- Matthew Brehove
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Elan Shatoff
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Benjamin T Donovan
- Biophysics Graduate Program, Ohio State University, Columbus, OH 43210, USA
| | - Caroline M Jipa
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Ralf Bundschuh
- Department of Physics, Ohio State University, Columbus, OH 43210, USA.,Biophysics Graduate Program, Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA.,Division of Hematology, Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
| | - Michael G Poirier
- Department of Physics, Ohio State University, Columbus, OH 43210, USA.,Biophysics Graduate Program, Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA.,Ohio State Biochemistry Program, Ohio State University, Columbus, OH 43210, USA
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15
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Zhao D, Le JV, Darcy MA, Crocker K, Poirier MG, Castro C, Bundschuh R. Quantitative Modeling of Nucleosome Unwrapping from Both Ends. Biophys J 2019; 117:2204-2216. [PMID: 31732143 DOI: 10.1016/j.bpj.2019.09.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 08/05/2019] [Accepted: 09/27/2019] [Indexed: 01/08/2023] Open
Abstract
In eukaryotic cells, DNA is packaged into chromatin where nucleosomes are the basic packaging unit. Important cellular processes including gene expression, DNA replication, and DNA repair require nucleosomal DNA to be unwrapped so that functional proteins can access their target sites, which otherwise are sterically occluded. A key question in this process is what the unwrapped conformations individual nucleosomes adopt within chromatin are. Here, we develop a concurrent nucleosome unwrapping model to address this question. We hypothesize that for a given end-to-end distance of the nucleosomal DNA, the nucleosomal DNA stochastically unwraps from the histone core from both ends independently and that this combination of unwrapping from both sides results in a significant increase in the average distance between the DNA extending from both sides of the nucleosomes. We test our model on recently published experiments using a DNA origami nanocaliper that quantifies nucleosome unwrapping and achieve good agreement between experiment and model prediction. We then investigate the DNA origami caliper distribution when attached to a hexasome (a nucleosome lacking an H2A/H2B dimer). A significant shift in the caliper angle distribution caused by the asymmetric structural features of the hexasome seen experimentally is consistent with the model. Our modeling approach may be more broadly useful to the interpretation of other studies of nucleosome dynamics, chromatin dynamics, and regulatory processes involving nucleosome unwrapping, as well as more generally to optimization of future DNA origami designs to probe mechanical properties of biomolecules.
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Affiliation(s)
- Dengke Zhao
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio
| | - Jenny V Le
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio
| | - Michael A Darcy
- Department of Physics, The Ohio State University, Columbus, Ohio
| | - Kyle Crocker
- Department of Physics, The Ohio State University, Columbus, Ohio
| | - Michael G Poirier
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio; Department of Physics, The Ohio State University, Columbus, Ohio; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Carlos Castro
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio; Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio
| | - Ralf Bundschuh
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio; Department of Physics, The Ohio State University, Columbus, Ohio; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio; Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, Ohio; Center for RNA Biology, The Ohio State University, Columbus, Ohio.
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16
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Abstract
Nucleosomes and chromatin control eukaryotic genome accessibility and thereby regulate DNA processes, including transcription, replication, and repair. Conformational dynamics within the nucleosome and chromatin structure play a key role in this regulatory function. Structural fluctuations continuously expose internal DNA sequences and nucleosome surfaces, thereby providing transient access for the nuclear machinery. Progress in structural studies of nucleosomes and chromatin has provided detailed insight into local chromatin organization and has set the stage for recent in-depth investigations of the structural dynamics of nucleosomes and chromatin fibers. Here, we discuss the dynamic processes observed in chromatin over different length scales and timescales and review current knowledge about the biophysics of distinct structural transitions.
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Affiliation(s)
- Beat Fierz
- Laboratory of Biophysical Chemistry of Macromolecules, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Michael G. Poirier
- Department of Physics, Biophysics Graduate Program, Ohio State Biochemistry Graduate Program, and Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210-1117, USA
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17
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van der Veeken J, Zhong Y, Sharma R, Mazutis L, Dao P, Pe'er D, Leslie CS, Rudensky AY. Natural Genetic Variation Reveals Key Features of Epigenetic and Transcriptional Memory in Virus-Specific CD8 T Cells. Immunity 2019; 50:1202-1217.e7. [PMID: 31027997 DOI: 10.1016/j.immuni.2019.03.031] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 01/15/2019] [Accepted: 03/27/2019] [Indexed: 12/29/2022]
Abstract
Stable changes in chromatin states and gene expression in cells of the immune system form the basis for memory of infections and other challenges. Here, we used naturally occurring cis-regulatory variation in wild-derived inbred mouse strains to explore the mechanisms underlying long-lasting versus transient gene regulation in CD8 T cells responding to acute viral infection. Stably responsive DNA elements were characterized by dramatic and congruent chromatin remodeling events affecting multiple neighboring sites and required distinct transcription factor (TF) binding motifs for their accessibility. Specifically, we found that cooperative recruitment of T-box and Runx family transcription factors to shared targets mediated stable chromatin remodeling upon T cell activation. Our observations provide insights into the molecular mechanisms driving virus-specific CD8 T cell responses and suggest a general mechanism for the formation of transcriptional and epigenetic memory applicable to other immune and non-immune cells.
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Affiliation(s)
- Joris van der Veeken
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Ludwig Center at Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yi Zhong
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Ludwig Center at Memorial Sloan Kettering Cancer Center, New York, NY, USA; Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Roshan Sharma
- Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA
| | - Linas Mazutis
- Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Phuong Dao
- Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Dana Pe'er
- Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Christina S Leslie
- Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alexander Y Rudensky
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Ludwig Center at Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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18
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Veil M, Yampolsky LY, Grüning B, Onichtchouk D. Pou5f3, SoxB1, and Nanog remodel chromatin on high nucleosome affinity regions at zygotic genome activation. Genome Res 2019; 29:383-395. [PMID: 30674556 PMCID: PMC6396415 DOI: 10.1101/gr.240572.118] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 01/16/2019] [Indexed: 12/16/2022]
Abstract
The zebrafish embryo is transcriptionally mostly quiescent during the first 10 cell cycles, until the main wave of zygotic genome activation (ZGA) occurs, accompanied by fast chromatin remodeling. At ZGA, homologs of the mammalian stem cell transcription factors (TFs) Pou5f3, Nanog, and Sox19b bind to thousands of developmental enhancers to initiate transcription. So far, how these TFs influence chromatin dynamics at ZGA has remained unresolved. To address this question, we analyzed nucleosome positions in wild-type and maternal-zygotic (MZ) mutants for pou5f3 and nanog by MNase-seq. We show that Nanog, Sox19b, and Pou5f3 bind to the high nucleosome affinity regions (HNARs). HNARs are spanning over 600 bp, featuring high in vivo and predicted in vitro nucleosome occupancy and high predicted propeller twist DNA shape value. We suggest a two-step nucleosome destabilization-depletion model, in which the same intrinsic DNA properties of HNAR promote both high nucleosome occupancy and differential binding of TFs. In the first step, already before ZGA, Pou5f3 and Nanog destabilize nucleosomes at HNAR centers genome-wide. In the second step, post-ZGA, Nanog, Pou5f3, and SoxB1 maintain open chromatin state on the subset of HNARs, acting synergistically. Nanog binds to the HNAR center, whereas the Pou5f3 stabilizes the flanks. The HNAR model will provide a useful tool for genome regulatory studies in a variety of biological systems.
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Affiliation(s)
- Marina Veil
- Department of Developmental Biology, Institute of Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104, Freiburg, Germany
| | - Lev Y Yampolsky
- Department of Biological Sciences, East Tennessee State University, Johnson City, Tennessee 37614-1710, USA.,Zoological Institute, Basel University, Basel, CH-4051 Switzerland
| | - Björn Grüning
- Department of Computer Science, Albert Ludwigs University of Freiburg, 79110, Freiburg, Germany.,Center for Biological Systems Analysis (ZBSA), University of Freiburg, 79104, Freiburg, Germany
| | - Daria Onichtchouk
- Department of Developmental Biology, Institute of Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104, Freiburg, Germany.,Signalling Research centers BIOSS and CIBSS, 79104, Freiburg, Germany.,Institute of Developmental Biology RAS, 119991 Moscow, Russia
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19
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Vierbuchen T, Ling E, Cowley CJ, Couch CH, Wang X, Harmin DA, Roberts CWM, Greenberg ME. AP-1 Transcription Factors and the BAF Complex Mediate Signal-Dependent Enhancer Selection. Mol Cell 2018; 68:1067-1082.e12. [PMID: 29272704 DOI: 10.1016/j.molcel.2017.11.026] [Citation(s) in RCA: 250] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 09/16/2017] [Accepted: 11/17/2017] [Indexed: 02/08/2023]
Abstract
Enhancer elements are genomic regulatory sequences that direct the selective expression of genes so that genetically identical cells can differentiate and acquire the highly specialized forms and functions required to build a functioning animal. To differentiate, cells must select from among the ∼106 enhancers encoded in the genome the thousands of enhancers that drive the gene programs that impart their distinct features. We used a genetic approach to identify transcription factors (TFs) required for enhancer selection in fibroblasts. This revealed that the broadly expressed, growth-factor-inducible TFs FOS/JUN (AP-1) play a central role in enhancer selection. FOS/JUN selects enhancers together with cell-type-specific TFs by collaboratively binding to nucleosomal enhancers and recruiting the SWI/SNF (BAF) chromatin remodeling complex to establish accessible chromatin. These experiments demonstrate how environmental signals acting via FOS/JUN and BAF coordinate with cell-type-specific TFs to select enhancer repertoires that enable differentiation during development.
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Affiliation(s)
- Thomas Vierbuchen
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.
| | - Emi Ling
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Christopher J Cowley
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Cameron H Couch
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Xiaofeng Wang
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - David A Harmin
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Charles W M Roberts
- Comprehensive Cancer Center and Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Michael E Greenberg
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
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20
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Trott AJ, Menet JS. Regulation of circadian clock transcriptional output by CLOCK:BMAL1. PLoS Genet 2018; 14:e1007156. [PMID: 29300726 PMCID: PMC5771620 DOI: 10.1371/journal.pgen.1007156] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 01/17/2018] [Accepted: 12/14/2017] [Indexed: 01/20/2023] Open
Abstract
The mammalian circadian clock relies on the transcription factor CLOCK:BMAL1 to coordinate the rhythmic expression of 15% of the transcriptome and control the daily regulation of biological functions. The recent characterization of CLOCK:BMAL1 cistrome revealed that although CLOCK:BMAL1 binds synchronously to all of its target genes, its transcriptional output is highly heterogeneous. By performing a meta-analysis of several independent genome-wide datasets, we found that the binding of other transcription factors at CLOCK:BMAL1 enhancers likely contribute to the heterogeneity of CLOCK:BMAL1 transcriptional output. While CLOCK:BMAL1 rhythmic DNA binding promotes rhythmic nucleosome removal, it is not sufficient to generate transcriptionally active enhancers as assessed by H3K27ac signal, RNA Polymerase II recruitment, and eRNA expression. Instead, the transcriptional activity of CLOCK:BMAL1 enhancers appears to rely on the activity of ubiquitously expressed transcription factors, and not tissue-specific transcription factors, recruited at nearby binding sites. The contribution of other transcription factors is exemplified by how fasting, which effects several transcription factors but not CLOCK:BMAL1, either decreases or increases the amplitude of many rhythmically expressed CLOCK:BMAL1 target genes. Together, our analysis suggests that CLOCK:BMAL1 promotes a transcriptionally permissive chromatin landscape that primes its target genes for transcription activation rather than directly activating transcription, and provides a new framework to explain how environmental or pathological conditions can reprogram the rhythmic expression of clock-controlled genes.
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Affiliation(s)
- Alexandra J. Trott
- Department of Biology, Program of Genetics and Center for Biological Clocks Research, Texas A&M University, College Station, TX, United States of America
| | - Jerome S. Menet
- Department of Biology, Program of Genetics and Center for Biological Clocks Research, Texas A&M University, College Station, TX, United States of America
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21
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Melamed P, Haj M, Yosefzon Y, Rudnizky S, Wijeweera A, Pnueli L, Kaplan A. Multifaceted Targeting of the Chromatin Mediates Gonadotropin-Releasing Hormone Effects on Gene Expression in the Gonadotrope. Front Endocrinol (Lausanne) 2018; 9:58. [PMID: 29535683 PMCID: PMC5835078 DOI: 10.3389/fendo.2018.00058] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) stimulates the expression of multiple genes in the pituitary gonadotropes, most notably to induce synthesis of the gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), but also to ensure the appropriate functioning of these cells at the center of the mammalian reproductive endocrine axis. Aside from the activation of gene-specific transcription factors, GnRH stimulates through its membrane-bound receptor, alterations in the chromatin that facilitate transcription of its target genes. These include changes in the histone and DNA modifications, nucleosome positioning, and chromatin packaging at the regulatory regions of each gene. The requirements for each of these events vary according to the DNA sequence which determines the basal chromatin packaging at the regulatory regions. Despite considerable progress in this field in recent years, we are only beginning to understand some of the complexities involved in the role and regulation of this chromatin structure, including new modifications, extensive cross talk, histone variants, and the actions of distal enhancers and non-coding RNAs. This short review aims to integrate the latest findings on GnRH-induced alterations in the chromatin of its target genes, which indicate multiple and diverse actions. Understanding these processes is illuminating not only in the context of the activation of these hormones during the reproductive life span but may also reveal how aberrant epigenetic regulation of these genes leads to sub-fertility.
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Affiliation(s)
- Philippa Melamed
- Faculty of Biology, Technion—Israel Institute of Technology, Haifa, Israel
- *Correspondence: Philippa Melamed,
| | - Majd Haj
- Faculty of Biology, Technion—Israel Institute of Technology, Haifa, Israel
| | - Yahav Yosefzon
- Faculty of Biology, Technion—Israel Institute of Technology, Haifa, Israel
| | - Sergei Rudnizky
- Faculty of Biology, Technion—Israel Institute of Technology, Haifa, Israel
| | - Andrea Wijeweera
- Faculty of Biology, Technion—Israel Institute of Technology, Haifa, Israel
| | - Lilach Pnueli
- Faculty of Biology, Technion—Israel Institute of Technology, Haifa, Israel
| | - Ariel Kaplan
- Faculty of Biology, Technion—Israel Institute of Technology, Haifa, Israel
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22
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Culkin J, de Bruin L, Tompitak M, Phillips R, Schiessel H. The role of DNA sequence in nucleosome breathing. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2017; 40:106. [PMID: 29185124 PMCID: PMC7001874 DOI: 10.1140/epje/i2017-11596-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 11/14/2017] [Indexed: 05/05/2023]
Abstract
Roughly 3/4 of human genomes are sequestered by nucleosomes, DNA spools with a protein core, dictating a broad range of biological processes, ranging from gene regulation, recombination, and replication, to chromosome condensation. Nucleosomes are dynamical structures and temporarily expose wrapped DNA through spontaneous unspooling from either end, a process called site exposure or nucleosome breathing. Here we ask how this process is influenced by the mechanical properties of the wrapped DNA, which is known to depend on the underlying base pair sequence. Using a coarse-grained nucleosome model we calculate the accessibility profiles for site exposure. We find that the process is very sensitive to sequence effects, so that evolution could potentially tune the accessibility of nucleosomal DNA and would only need a small number of mutations to do so.
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Affiliation(s)
- Jamie Culkin
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands
| | - Lennart de Bruin
- Laboratory for Computation and Visualization in Mathematics and Mechanics, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
| | - Marco Tompitak
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands
| | - Rob Phillips
- Department of Applied Physics and Division of Biology and Biological Engineering, California Institute of Technology, 91125, Pasadena, CA, USA
| | - Helmut Schiessel
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands.
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23
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Theißen G, Melzer R, Rümpler F. MADS-domain transcription factors and the floral quartet model of flower development: linking plant development and evolution. Development 2017; 143:3259-71. [PMID: 27624831 DOI: 10.1242/dev.134080] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The floral quartet model of floral organ specification poses that different tetramers of MIKC-type MADS-domain transcription factors control gene expression and hence the identity of floral organs during development. Here, we provide a brief history of the floral quartet model and review several lines of recent evidence that support the model. We also describe how the model has been used in contemporary developmental and evolutionary biology to shed light on enigmatic topics such as the origin of land and flowering plants. Finally, we suggest a novel hypothesis describing how floral quartet-like complexes may interact with chromatin during target gene activation and repression.
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Affiliation(s)
- Günter Theißen
- Department of Genetics, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Rainer Melzer
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Florian Rümpler
- Department of Genetics, Friedrich Schiller University Jena, 07743 Jena, Germany
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24
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Cuvier O, Fierz B. Dynamic chromatin technologies: from individual molecules to epigenomic regulation in cells. Nat Rev Genet 2017; 18:457-472. [DOI: 10.1038/nrg.2017.28] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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25
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Reiter F, Wienerroither S, Stark A. Combinatorial function of transcription factors and cofactors. Curr Opin Genet Dev 2017; 43:73-81. [PMID: 28110180 DOI: 10.1016/j.gde.2016.12.007] [Citation(s) in RCA: 190] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/14/2016] [Accepted: 12/21/2016] [Indexed: 12/31/2022]
Abstract
Differential gene expression gives rise to the many cell types of complex organisms. Enhancers regulate transcription by binding transcription factors (TFs), which in turn recruit cofactors to activate RNA Polymerase II at core promoters. Transcriptional regulation is typically mediated by distinct combinations of TFs, enabling a relatively small number of TFs to generate a large diversity of cell types. However, how TFs achieve combinatorial enhancer control and how enhancers, enhancer-bound TFs, and the cofactors they recruit regulate RNA Polymerase II activity is not entirely clear. Here, we review how TF synergy is mediated at the level of DNA binding and after binding, the role of cofactors and the post-translational modifications they catalyze, and discuss different models of enhancer-core-promoter communication.
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Affiliation(s)
- Franziska Reiter
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Sebastian Wienerroither
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Alexander Stark
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria.
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CENP-A and H3 Nucleosomes Display a Similar Stability to Force-Mediated Disassembly. PLoS One 2016; 11:e0165078. [PMID: 27820823 PMCID: PMC5098787 DOI: 10.1371/journal.pone.0165078] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 10/05/2016] [Indexed: 12/12/2022] Open
Abstract
Centromere-specific nucleosomes are a central feature of the kinetochore complex during mitosis, in which microtubules exert pulling and pushing forces upon the centromere. CENP-A nucleosomes have been assumed to be structurally unique, thereby providing resilience under tension relative to their H3 canonical counterparts. Here, we directly test this hypothesis by subjecting CENP-A and H3 octameric nucleosomes, assembled on random or on centromeric DNA sequences, to varying amounts of applied force by using single-molecule magnetic tweezers. We monitor individual disassembly events of CENP-A and H3 nucleosomes. Regardless of the DNA sequence, the force-mediated disassembly experiments for CENP-A and H3 nucleosomes demonstrate similar rupture forces, life time residency and disassembly steps. From these experiments, we conclude that CENP-A does not, by itself, contribute unique structural features to the nucleosome that lead to a significant resistance against force-mediated disruption. The data present insights into the mechanistic basis for how CENP-A nucleosomes might contribute to the structural foundation of the centromere in vivo.
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27
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Lequieu J, Córdoba A, Schwartz DC, de Pablo JJ. Tension-Dependent Free Energies of Nucleosome Unwrapping. ACS CENTRAL SCIENCE 2016; 2:660-666. [PMID: 27725965 PMCID: PMC5043429 DOI: 10.1021/acscentsci.6b00201] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 05/20/2023]
Abstract
Nucleosomes form the basic unit of compaction within eukaryotic genomes, and their locations represent an important, yet poorly understood, mechanism of genetic regulation. Quantifying the strength of interactions within the nucleosome is a central problem in biophysics and is critical to understanding how nucleosome positions influence gene expression. By comparing to single-molecule experiments, we demonstrate that a coarse-grained molecular model of the nucleosome can reproduce key aspects of nucleosome unwrapping. Using detailed simulations of DNA and histone proteins, we calculate the tension-dependent free energy surface corresponding to the unwrapping process. The model reproduces quantitatively the forces required to unwrap the nucleosome and reveals the role played by electrostatic interactions during this process. We then demonstrate that histone modifications and DNA sequence can have significant effects on the energies of nucleosome formation. Most notably, we show that histone tails contribute asymmetrically to the stability of the outer and inner turn of nucleosomal DNA and that depending on which histone tails are modified, the tension-dependent response is modulated differently.
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Affiliation(s)
- Joshua Lequieu
- Institute
for Molecular Engineering, University of
Chicago, Chicago, Illinois 60637, United
States
| | - Andrés Córdoba
- Institute
for Molecular Engineering, University of
Chicago, Chicago, Illinois 60637, United
States
| | - David C. Schwartz
- Laboratory
for Molecular and Computational Genomics, Department of Chemistry,
Laboratory of Genetics, and UW-Biotechnology Center, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Juan J. de Pablo
- Institute
for Molecular Engineering, University of
Chicago, Chicago, Illinois 60637, United
States
- Materials
Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
- E-mail:
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28
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Eslami-Mossallam B, Schiessel H, van Noort J. Nucleosome dynamics: Sequence matters. Adv Colloid Interface Sci 2016; 232:101-113. [PMID: 26896338 DOI: 10.1016/j.cis.2016.01.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 01/22/2016] [Accepted: 01/25/2016] [Indexed: 02/06/2023]
Abstract
About three quarter of all eukaryotic DNA is wrapped around protein cylinders, forming nucleosomes. Even though the histone proteins that make up the core of nucleosomes are highly conserved in evolution, nucleosomes can be very different from each other due to posttranslational modifications of the histones. Another crucial factor in making nucleosomes unique has so far been underappreciated: the sequence of their DNA. This review provides an overview of the experimental and theoretical progress that increasingly points to the importance of the nucleosomal base pair sequence. Specifically, we discuss the role of the underlying base pair sequence in nucleosome positioning, sliding, breathing, force-induced unwrapping, dissociation and partial assembly and also how the sequence can influence higher-order structures. A new view emerges: the physical properties of nucleosomes, especially their dynamical properties, are determined to a large extent by the mechanical properties of their DNA, which in turn depends on DNA sequence.
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de Bruin L, Tompitak M, Eslami-Mossallam B, Schiessel H. Why Do Nucleosomes Unwrap Asymmetrically? J Phys Chem B 2016; 120:5855-63. [PMID: 26991771 DOI: 10.1021/acs.jpcb.6b00391] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nucleosomes, DNA spools with a protein core, engage about three-quarters of eukaryotic DNA and play a critical role in chromosomal processes, ranging from gene regulation, recombination, and replication to chromosome condensation. For more than a decade, micromanipulation experiments where nucleosomes are put under tension, as well as the theoretical interpretations of these experiments, have deepened our understanding of the stability and dynamics of nucleosomes. Here we give a theoretical explanation for a surprising new experimental finding: nucleosomes wrapped onto the 601 positioning sequence (the sequence used in most laboratories) respond highly asymmetrically to external forces by always unwrapping from the same end. Using a computational nucleosome model, we show that this asymmetry can be explained by differences in the DNA mechanics of two very short stretches on the wrapped DNA portion. Our finding suggests that the physical properties of nucleosomes, here the response to forces, can be tuned locally by the choice of the underlying base-pair sequence. This leads to a new view of nucleosomes: a physically highly varied set of DNA-protein complexes whose properties can be tuned on evolutionary time scales to their specific function in the genomic context.
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Affiliation(s)
- Lennart de Bruin
- Institute Lorentz for Theoretical Physics, Leiden University , Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Marco Tompitak
- Institute Lorentz for Theoretical Physics, Leiden University , Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Behrouz Eslami-Mossallam
- Institute Lorentz for Theoretical Physics, Leiden University , Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Helmut Schiessel
- Institute Lorentz for Theoretical Physics, Leiden University , Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
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30
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Zhou Y, Hartwig B, James GV, Schneeberger K, Turck F. Complementary Activities of TELOMERE REPEAT BINDING Proteins and Polycomb Group Complexes in Transcriptional Regulation of Target Genes. THE PLANT CELL 2016; 28:87-101. [PMID: 26721861 PMCID: PMC4746681 DOI: 10.1105/tpc.15.00787] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/11/2015] [Accepted: 12/25/2015] [Indexed: 05/19/2023]
Abstract
In multicellular organisms, Polycomb Repressive Complex 1 (PRC1) and PRC2 repress target genes through histone modification and chromatin compaction. Arabidopsis thaliana mutants strongly compromised in the pathway cannot develop differentiated organs. LIKE HETEROCHROMATIN PROTEIN1 (LHP1) is so far the only known plant PRC1 component that directly binds to H3K27me3, the histone modification set by PRC2, and also associates genome-wide with trimethylation of lysine 27 of histone H3 (H3K27me3). Surprisingly, lhp1 mutants show relatively mild phenotypic alterations. To explain this paradox, we screened for genetic enhancers of lhp1 mutants to identify novel components repressing target genes together with, or in parallel to, LHP1. Two enhancing mutations were mapped to TELOMERE REPEAT BINDING PROTEIN1 (TRB1) and its paralog TRB3. We show that TRB1 binds to thousands of genomic sites containing telobox or related cis-elements with a significant increase of sites and strength of binding in the lhp1 background. Furthermore, in combination with lhp1, but not alone, trb1 mutants show increased transcription of LHP1 targets, such as floral meristem identity genes, which are more likely to be bound by TRB1 in the lhp1 background. By contrast, expression of a subset of LHP1-independent TRB1 target genes, many involved in primary metabolism, is decreased in the absence of TRB1 alone. Thus, TRB1 is a bivalent transcriptional modulator that maintains downregulation of Polycomb Group (PcG) target genes in lhp1 mutants, while it sustains high expression of targets that are regulated independently of PcG.
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Affiliation(s)
- Yue Zhou
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Benjamin Hartwig
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Geo Velikkakam James
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Korbinian Schneeberger
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Franziska Turck
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
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31
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Li M, Hada A, Sen P, Olufemi L, Hall MA, Smith BY, Forth S, McKnight JN, Patel A, Bowman GD, Bartholomew B, Wang MD. Dynamic regulation of transcription factors by nucleosome remodeling. eLife 2015; 4. [PMID: 26047462 PMCID: PMC4456607 DOI: 10.7554/elife.06249] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/11/2015] [Indexed: 12/27/2022] Open
Abstract
The chromatin landscape and promoter architecture are dominated by the interplay of nucleosome and transcription factor (TF) binding to crucial DNA sequence elements. However, it remains unclear whether nucleosomes mobilized by chromatin remodelers can influence TFs that are already present on the DNA template. In this study, we investigated the interplay between nucleosome remodeling, by either yeast ISW1a or SWI/SNF, and a bound TF. We found that a TF serves as a major barrier to ISW1a remodeling, and acts as a boundary for nucleosome repositioning. In contrast, SWI/SNF was able to slide a nucleosome past a TF, with concurrent eviction of the TF from the DNA, and the TF did not significantly impact the nucleosome positioning. Our results provide direct evidence for a novel mechanism for both nucleosome positioning regulation by bound TFs and TF regulation via dynamic repositioning of nucleosomes. DOI:http://dx.doi.org/10.7554/eLife.06249.001 Cells contain thousands of genes that are encoded by molecules of DNA. In yeast and other eukaryotic organisms, this DNA is wrapped around proteins called histones to make structures called nucleosomes. This compacts the DNA and allows it to fit inside the tiny nucleus within the cell. The positioning of the nucleosomes influences how tightly packed the DNA is, which in turn influences the activity of genes. Less active genes tend to be found within regions of DNA that are tightly packed, while more active genes are found in less tightly packed regions. To activate a gene, proteins called transcription factors bind to a section of DNA within the gene called the promoter. Enzymes known as ‘chromatin remodelers’ can alter the locations of nucleosomes on DNA to allow the transcription factors access to the promoters of particular genes. In yeast, the SWI/SNF family of chromatin remodelers can disassemble nucleosomes to promote gene activity, while the ISW1 family organises nucleosomes into closely spaced groups to repress gene activity. However, it is not clear if, or how, chromatin remodelers can influence transcription factors that are already bound to DNA. Here, Li et al. studied the interactions between a transcription factor and the chromatin remodelers in yeast. The experiment used a piece of DNA that contained a bound transcription factor and a single nucleosome. Li et al. used a technique called ‘single molecule DNA unzipping’, which enabled them to precisely locate the position of the nucleosome and transcription factor before and after the nucleosome was remodeled. The experiments found that a chromatin remodeler called ISW1a moved the nucleosome away from the transcription factor, while a SWI/SNF chromatin remodeler moved the nucleosome towards it. Significantly, Li et al. also found that a transcription factor is a major barrier to ISW1a's remodeling activity, suggesting that ISW1a may use transcription factors as reference points to position nucleosomes. In contrast, SWI/SNF was able to slide a nucleosome past the transcription factor, which led to the transcription factor falling off the DNA. Therefore, SWI/SNF is able to move transcription factors out of the way to deactivate genes. Li et al. propose a new model for how chromatin remodelers can move nucleosomes and regulate transcription factors to alter gene activity. A future challenge will be to observe these types of activities in living cells. DOI:http://dx.doi.org/10.7554/eLife.06249.002
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Affiliation(s)
- Ming Li
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, United States
| | - Arjan Hada
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Payel Sen
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Lola Olufemi
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Michael A Hall
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Benjamin Y Smith
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Scott Forth
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Jeffrey N McKnight
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Ashok Patel
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Gregory D Bowman
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Blaine Bartholomew
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Michelle D Wang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
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32
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Sebeson A, Xi L, Zhang Q, Sigmund A, Wang JP, Widom J, Wang X. Differential Nucleosome Occupancies across Oct4-Sox2 Binding Sites in Murine Embryonic Stem Cells. PLoS One 2015; 10:e0127214. [PMID: 25992972 PMCID: PMC4436218 DOI: 10.1371/journal.pone.0127214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 04/13/2015] [Indexed: 12/03/2022] Open
Abstract
The binding sequence for any transcription factor can be found millions of times within a genome, yet only a small fraction of these sequences encode functional transcription factor binding sites. One of the reasons for this dichotomy is that many other factors, such as nucleosomes, compete for binding. To study how the competition between nucleosomes and transcription factors helps determine a functional transcription factor site from a predicted transcription factor site, we compared experimentally-generated in vitro nucleosome occupancy with in vivo nucleosome occupancy and transcription factor binding in murine embryonic stem cells. Using a solution hybridization enrichment technique, we generated a high-resolution nucleosome map from targeted regions of the genome containing predicted sites and functional sites of Oct4/Sox2 regulation. We found that at Pax6 and Nes, which are bivalently poised in stem cells, functional Oct4 and Sox2 sites show high amounts of in vivo nucleosome displacement compared to in vitro. Oct4 and Sox2, which are active, show no significant displacement of in vivo nucleosomes at functional sites, similar to nonfunctional Oct4/Sox2 binding. This study highlights a complex interplay between Oct4 and Sox2 transcription factors and nucleosomes among different target genes, which may result in distinct patterns of stem cell gene regulation.
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Affiliation(s)
- Amy Sebeson
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Liqun Xi
- Department of Statistics, Northwestern University, Evanston, Illinois, United States of America
| | - Quanwei Zhang
- Department of Statistics, Northwestern University, Evanston, Illinois, United States of America
| | - Audrey Sigmund
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Ji-Ping Wang
- Department of Statistics, Northwestern University, Evanston, Illinois, United States of America
- * E-mail: (XW); (J-PW)
| | - Jonathan Widom
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Xiaozhong Wang
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- * E-mail: (XW); (J-PW)
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33
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Buecker C, Srinivasan R, Wu Z, Calo E, Acampora D, Faial T, Simeone A, Tan M, Swigut T, Wysocka J. Reorganization of enhancer patterns in transition from naive to primed pluripotency. Cell Stem Cell 2015; 14:838-53. [PMID: 24905168 DOI: 10.1016/j.stem.2014.04.003] [Citation(s) in RCA: 343] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/17/2014] [Accepted: 04/07/2014] [Indexed: 12/19/2022]
Abstract
Naive and primed pluripotency is characterized by distinct signaling requirements, transcriptomes, and developmental properties, but both cellular states share key transcriptional regulators: Oct4, Sox2, and Nanog. Here, we demonstrate that transition between these two pluripotent states is associated with widespread Oct4 relocalization, mirrored by global rearrangement of enhancer chromatin landscapes. Our genomic and biochemical analyses identified candidate mediators of primed state-specific Oct4 binding, including Otx2 and Zic2/3. Even when differentiation cues are blocked, premature Otx2 overexpression is sufficient to exit the naive state, induce transcription of a substantial subset of primed pluripotency-associated genes, and redirect Oct4 to previously inaccessible enhancer sites. However, the ability of Otx2 to engage new enhancer regions is determined by its levels, cis-encoded properties of the sites, and the signaling environment. Our results illuminate regulatory mechanisms underlying pluripotency and suggest that the capacity of transcription factors such as Otx2 and Oct4 to pioneer new enhancer sites is highly context dependent.
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Affiliation(s)
- Christa Buecker
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Rajini Srinivasan
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zhixiang Wu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Eliezer Calo
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Dario Acampora
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso," CNR, Via P. Castellino, 111, 80131 Naples, Italy; IRCCS Neuromed, 86077 Pozzilli (IS), Italy
| | - Tiago Faial
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Antonio Simeone
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso," CNR, Via P. Castellino, 111, 80131 Naples, Italy; IRCCS Neuromed, 86077 Pozzilli (IS), Italy
| | - Minjia Tan
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Tomasz Swigut
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Joanna Wysocka
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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34
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Lenz L, Hoenderdos M, Prinsen P, Schiessel H. The influence of DNA shape fluctuations on fluorescence resonance energy transfer efficiency measurements in nucleosomes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:064104. [PMID: 25564291 DOI: 10.1088/0953-8984/27/6/064104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fluorescence resonance energy transfer (FRET) measurements allow one to observe site exposure in nucleosomes, i.e. the transient unwrapping of a part of the wrapped DNA from the histone octamer. In such experiments one can typically distinguish between a closed state and an open state but in principle one might hope to detect several states, each corresponding to a certain number of open binding sites. Here we show that even in an ideal FRET setup it would be hard to detect unwrapping states with intermediate levels of FRET efficiencies. As the unwrapped DNA molecule, modelled here as a wormlike chain, has a finite stiffness, shape fluctuations smear out FRET signals completely from such intermediate states.
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Affiliation(s)
- Lucia Lenz
- Instituut-Lorentz, Leiden University, PO Box 9506, 2300 RA Leiden, The Netherlands. Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Albertstr. 19, 79104 Freiburg im Breisgau, Germany
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35
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Abstract
Biochemical and genomic studies have shown that transcription factors with the highest reprogramming activity often have the special ability to engage their target sites on nucleosomal DNA, thus behaving as “pioneer factors” to initiate events in closed chromatin. This review by Iwafuchi-Doi and Zaret focuses on the most recent studies of pioneer factors in cell programming and reprogramming, how pioneer factors have special chromatin-binding properties, and facilitators and impediments to chromatin binding. A subset of eukaryotic transcription factors possesses the remarkable ability to reprogram one type of cell into another. The transcription factors that reprogram cell fate are invariably those that are crucial for the initial cell programming in embryonic development. To elicit cell programming or reprogramming, transcription factors must be able to engage genes that are developmentally silenced and inappropriate for expression in the original cell. Developmentally silenced genes are typically embedded in “closed” chromatin that is covered by nucleosomes and not hypersensitive to nuclease probes such as DNase I. Biochemical and genomic studies have shown that transcription factors with the highest reprogramming activity often have the special ability to engage their target sites on nucleosomal DNA, thus behaving as “pioneer factors” to initiate events in closed chromatin. Other reprogramming factors appear dependent on pioneer factors for engaging nucleosomes and closed chromatin. However, certain genomic domains in which nucleosomes are occluded by higher-order chromatin structures, such as in heterochromatin, are resistant to pioneer factor binding. Understanding the means by which pioneer factors can engage closed chromatin and how heterochromatin can prevent such binding promises to advance our ability to reprogram cell fates at will and is the topic of this review.
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Affiliation(s)
- Makiko Iwafuchi-Doi
- Institute for Regenerative Medicine, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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36
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Abstract
Nucleosome is a histone-DNA complex known as the fundamental repeating unit of chromatin. Up to 90% of eukaryotic DNA is wrapped around consecutive octamers made of the core histones H2A, H2B, H3 and H4. Nucleosome positioning affects numerous cellular processes that require robust and timely access to genomic DNA, which is packaged into the tight confines of the cell nucleus. In living cells, nucleosome positions are determined by intrinsic histone-DNA sequence preferences, competition between histones and other DNA-binding proteins for genomic sequence, and ATP-dependent chromatin remodelers. We discuss the major energetic contributions to nucleosome formation and remodeling, focusing especially on partial DNA unwrapping off the histone octamer surface. DNA unwrapping enables efficient access to nucleosome-buried binding sites and mediates rapid nucleosome removal through concerted action of two or more DNA-binding factors. High-resolution, genome-scale maps of distances between neighboring nucleosomes have shown that DNA unwrapping and nucleosome crowding (mutual invasion of nucleosome territories) are much more common than previously thought. Ultimately, constraints imposed by nucleosome energetics on the rates of ATP-dependent and spontaneous chromatin remodeling determine nucleosome occupancy genome-wide, and shape pathways of cellular response to environmental stresses.
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37
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Taguchi H, Horikoshi N, Arimura Y, Kurumizaka H. A method for evaluating nucleosome stability with a protein-binding fluorescent dye. Methods 2014; 70:119-26. [DOI: 10.1016/j.ymeth.2014.08.019] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 08/26/2014] [Accepted: 08/28/2014] [Indexed: 11/29/2022] Open
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38
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Jetha K, Theißen G, Melzer R. Arabidopsis SEPALLATA proteins differ in cooperative DNA-binding during the formation of floral quartet-like complexes. Nucleic Acids Res 2014; 42:10927-42. [PMID: 25183521 PMCID: PMC4176161 DOI: 10.1093/nar/gku755] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The SEPALLATA (SEP) genes of Arabidopsis thaliana encode MADS-domain transcription factors that specify the identity of all floral organs. The four Arabidopsis SEP genes function in a largely yet not completely redundant manner. Here, we analysed interactions of the SEP proteins with DNA. All of the proteins were capable of forming tetrameric quartet-like complexes on DNA fragments carrying two sequence elements termed CArG-boxes. Distances between the CArG-boxes for strong cooperative DNA-binding were in the range of 4-6 helical turns. However, SEP1 also bound strongly to CArG-box pairs separated by smaller or larger distances, whereas SEP2 preferred large and SEP4 preferred small inter-site distances for binding. Cooperative binding of SEP3 was comparatively weak for most of the inter-site distances tested. All SEP proteins constituted floral quartet-like complexes together with the floral homeotic proteins APETALA3 (AP3) and PISTILLATA (PI) on the target genes AP3 and SEP3. Our results suggest an important part of an explanation for why the different SEP proteins have largely, but not completely redundant functions in determining floral organ identity: they may bind to largely overlapping, but not identical sets of target genes that differ in the arrangement and spacing of the CArG-boxes in their cis-regulatory regions.
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Affiliation(s)
- Khushboo Jetha
- Department of Genetics, Friedrich Schiller University Jena, Philosophenweg 12, D-07743 Jena, Germany
| | - Günter Theißen
- Department of Genetics, Friedrich Schiller University Jena, Philosophenweg 12, D-07743 Jena, Germany
| | - Rainer Melzer
- Department of Genetics, Friedrich Schiller University Jena, Philosophenweg 12, D-07743 Jena, Germany Department of Genetics, Institute of Biology, University of Leipzig, Talstraße 33, D-04103 Leipzig, Germany
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39
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Prabhu AV, Sharpe LJ, Brown AJ. The sterol-based transcriptional control of human 7-dehydrocholesterol reductase (DHCR7): Evidence of a cooperative regulatory program in cholesterol synthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1842:1431-9. [PMID: 25048193 DOI: 10.1016/j.bbalip.2014.07.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 06/20/2014] [Accepted: 07/07/2014] [Indexed: 02/01/2023]
Abstract
The enzyme 7-dehydrocholesterol reductase (DHCR7) catalyzes the final step of cholesterol synthesis via the Kandutsch-Russell pathway, and is crucial in maintaining cellular cholesterol levels. Its absence leads to the devastating fetal developmental disorder Smith-Lemli-Opitz Syndrome (SLOS). How this enzyme is regulated has implications in controlling not only cholesterol synthesis, but also the synthesis of Vitamin D - another product of 7-dehydrocholesterol. In this study, we look specifically at how DHCR7 is regulated by the sterol regulatory element-binding protein-2 (SREBP-2) transcription factor. Sterol regulation has previously been studied in the rat DHCR7 promoter, but we have found that its regulatory elements are not all conserved in humans. Rather, the human promoter contains two binding sites for SREBP-2 (at -155 and -55) and a binding site for the nuclear factor-Y (NF-Y) cofactor (at -136). The -155 site is a particularly responsive sterol regulatory element (SRE) which is well conserved in mammals, and was possibly overlooked in the rat promoter study. The exact location of the weaker -55 site (close to the known rat SRE) may have shifted during evolution. Furthermore, we established that the two SREs that bind SREBP-2 work in cooperation to synergistically activate DHCR7. We have previously characterized the SREs in DHCR24, the final enzyme in the alternate Bloch pathway of cholesterol synthesis. Here, comparison of the sterol regulation of these terminal enzymes demonstrates the unique cooperative system that helps to control cholesterol synthesis.
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Affiliation(s)
- Anika V Prabhu
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Laura J Sharpe
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
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Abstract
Nucleosomes may undergo a conformational change in which a stretch of DNA peels off the histone octamer surface as a result of thermal fluctuations or interactions with chromatin remodelers. Thus, neighboring nucleosomes may invade each other's territories by DNA unwrapping and translocation, or through initial assembly in partially wrapped states. A recent high-resolution map of distances between dyads of neighboring nucleosomes in Saccharomyces cerevisiae reveals that nucleosomes frequently overlap DNA territories of their neighbors. This conclusion is supported by lower-resolution maps of S. cerevisiae nucleosome lengths based on micrococcal nuclease digestion and paired-end sequencing. The average length of wrapped DNA follows a stereotypical pattern in genes and promoters, correlated with the well-known distribution of nucleosome occupancy: nucleosomal DNA tends to be shorter in promoters and longer in coding regions. To explain these observations, we have developed a biophysical model that uses a 10-11-bp periodic histone-DNA binding energy profile. The profile is based on the pattern of histone-DNA contacts in nucleosome crystal structures, as well as the idea of linker length discretization caused by higher-order chromatin structure. Our model is in agreement with the observed genome-wide distributions of interdyad distances, wrapped DNA lengths, and nucleosome occupancies. Furthermore, our approach explains in vitro measurements of the accessibility of nucleosome-covered target sites and nucleosome-induced cooperativity between DNA-binding factors. We rule out several alternative scenarios of histone-DNA interactions as inconsistent with the genomic data.
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Elfving N, Chereji RV, Bharatula V, Björklund S, Morozov AV, Broach JR. A dynamic interplay of nucleosome and Msn2 binding regulates kinetics of gene activation and repression following stress. Nucleic Acids Res 2014; 42:5468-82. [PMID: 24598258 PMCID: PMC4027177 DOI: 10.1093/nar/gku176] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The transcription factor Msn2 mediates a significant proportion of the environmental stress response, in which a common cohort of genes changes expression in a stereotypic fashion upon exposure to any of a wide variety of stresses. We have applied genome-wide chromatin immunoprecipitation and nucleosome profiling to determine where Msn2 binds under stressful conditions and how that binding affects, and is affected by, nucleosome positioning. We concurrently determined the effect of Msn2 activity on gene expression following stress and demonstrated that Msn2 stimulates both activation and repression. We found that some genes responded to both intermittent and continuous Msn2 nuclear occupancy while others responded only to continuous occupancy. Finally, these studies document a dynamic interplay between nucleosomes and Msn2 such that nucleosomes can restrict access of Msn2 to its canonical binding sites while Msn2 can promote reposition, expulsion and recruitment of nucleosomes to alter gene expression. This interplay may allow the cell to discriminate between different types of stress signaling.
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Affiliation(s)
- Nils Elfving
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 901 87, Sweden
| | - Răzvan V Chereji
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - Vasudha Bharatula
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Stefan Björklund
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 901 87, Sweden
| | - Alexandre V Morozov
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA BioMaPS Institute for Quantitative Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - James R Broach
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
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42
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Kakei Y, Ogo Y, Itai RN, Kobayashi T, Yamakawa T, Nakanishi H, Nishizawa NK. Development of a novel prediction method of cis-elements to hypothesize collaborative functions of cis-element pairs in iron-deficient rice. RICE (NEW YORK, N.Y.) 2013; 6:22. [PMID: 24279975 PMCID: PMC4883709 DOI: 10.1186/1939-8433-6-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 09/13/2013] [Indexed: 05/20/2023]
Abstract
BACKGROUND Cis-acting elements are essential genomic sequences that control gene expression. In higher eukaryotes, a series of cis-elements function cooperatively. However, further studies are required to examine the co-regulation of multiple cis-elements on a promoter. The aim of this study was to propose a model of cis-element networks that cooperatively regulate gene expression in rice under iron (Fe) deficiency. RESULTS We developed a novel clustering-free method, microarray-associated motif analyzer (MAMA), to predict novel cis-acting elements based on weighted sequence similarities and gene expression profiles in microarray analyses. Simulation of gene expression was performed using a support vector machine and based on the presence of predicted motifs and motif pairs. The accuracy of simulated gene expression was used to evaluate the quality of prediction and to optimize the parameters used in this method. Based on sequences of Oryza sativa genes upregulated by Fe deficiency, MAMA returned experimentally identified cis-elements responsible for Fe deficiency in O. sativa. When this method was applied to O. sativa subjected to zinc deficiency and Arabidopsis thaliana subjected to salt stress, several novel candidate cis-acting elements that overlap with known cis-acting elements, such as ZDRE, ABRE, and DRE, were identified. After optimization, MAMA accurately simulated more than 87% of gene expression. Predicted motifs strongly co-localized in the upstream regions of regulated genes and sequences around transcription start sites. Furthermore, in many cases, the separation (in bp) between co-localized motifs was conserved, suggesting that predicted motifs and the separation between them were important in the co-regulation of gene expression. CONCLUSIONS Our results are suggestive of a typical sequence model for Fe deficiency-responsive promoters and some strong candidate cis-elements that function cooperatively with known cis-elements.
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Affiliation(s)
- Yusuke Kakei
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Plant Biotechnology Division, Yokohama City University, Kihara Institute for Biological Research Maiokacho, 641-12, Totsuka, Yokohama, Kanagawa 244-0813 Japan
| | - Yuko Ogo
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Functional Transgenic Crops Research Unit, Genetically Modified Organism Research Center National Institute of Agrobiological Sciences, Kannondai 2-1-2, 305-8602 Tsukuba, Ibaraki Japan
| | - Reiko N Itai
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
| | - Takanori Kobayashi
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, 921-8836 Nonoichi-machi, Ishikawa Japan
- />Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, 921-8836 Nonoichi-machi, Ishikawa Japan
| | - Takashi Yamakawa
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
| | - Hiromi Nakanishi
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
| | - Naoko K Nishizawa
- />Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, 113-8657 Bunkyo-ku Tokyo, Japan
- />Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, 921-8836 Nonoichi-machi, Ishikawa Japan
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Cheng Q, Kazemian M, Pham H, Blatti C, Celniker SE, Wolfe SA, Brodsky MH, Sinha S. Computational identification of diverse mechanisms underlying transcription factor-DNA occupancy. PLoS Genet 2013; 9:e1003571. [PMID: 23935523 PMCID: PMC3731213 DOI: 10.1371/journal.pgen.1003571] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 05/02/2013] [Indexed: 12/13/2022] Open
Abstract
ChIP-based genome-wide assays of transcription factor (TF) occupancy have emerged as a powerful, high-throughput method to understand transcriptional regulation, especially on a global scale. This has led to great interest in the underlying biochemical mechanisms that direct TF-DNA binding, with the ultimate goal of computationally predicting a TF's occupancy profile in any cellular condition. In this study, we examined the influence of various potential determinants of TF-DNA binding on a much larger scale than previously undertaken. We used a thermodynamics-based model of TF-DNA binding, called “STAP,” to analyze 45 TF-ChIP data sets from Drosophila embryonic development. We built a cross-validation framework that compares a baseline model, based on the ChIP'ed (“primary”) TF's motif, to more complex models where binding by secondary TFs is hypothesized to influence the primary TF's occupancy. Candidates interacting TFs were chosen based on RNA-SEQ expression data from the time point of the ChIP experiment. We found widespread evidence of both cooperative and antagonistic effects by secondary TFs, and explicitly quantified these effects. We were able to identify multiple classes of interactions, including (1) long-range interactions between primary and secondary motifs (separated by ≤150 bp), suggestive of indirect effects such as chromatin remodeling, (2) short-range interactions with specific inter-site spacing biases, suggestive of direct physical interactions, and (3) overlapping binding sites suggesting competitive binding. Furthermore, by factoring out the previously reported strong correlation between TF occupancy and DNA accessibility, we were able to categorize the effects into those that are likely to be mediated by the secondary TF's effect on local accessibility and those that utilize accessibility-independent mechanisms. Finally, we conducted in vitro pull-down assays to test model-based predictions of short-range cooperative interactions, and found that seven of the eight TF pairs tested physically interact and that some of these interactions mediate cooperative binding to DNA. Chromatin Immunoprecipitation (ChIP)-based genome-wide assays of transcription factor (TF) occupancy have emerged as a powerful, high throughput method to understand transcriptional regulation, especially on a global scale. Here, we utilize 45 ChIP-chip and ChIP-SEQ data sets from Drosophila to explore the underlying mechanisms of TF-DNA binding. For this, we employ a biophysically motivated computational model, in conjunction with over 300 TF motifs (binding specificities) as well as gene expression and DNA accessibility data from different developmental stages in Drosophila embryos. Our findings provide robust statistical evidence of the role played by TF-TF interactions in shaping genome-wide TF-DNA binding profiles, and thus in directing gene regulation. Our method allows us to go beyond simply recognizing the existence of such interactions, to quantifying their effects on TF occupancy. We are able to categorize the probable mechanisms of these effects as involving direct physical interactions versus accessibility-mediated indirect interactions, long-range versus short-range interactions, and cooperative versus antagonistic interactions. Our analysis reveals widespread evidence of combinatorial regulation present in recently generated ChIP data sets, and sets the stage for rich integrative models of the future that will predict cell type-specific TF occupancy values from sequence and expression data.
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Affiliation(s)
- Qiong Cheng
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Majid Kazemian
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Hannah Pham
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Charles Blatti
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Susan E. Celniker
- Department of Genome Dynamics, Berkeley Drosophila Genome Project, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Scot A. Wolfe
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Michael H. Brodsky
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail: (MHB); (SS)
| | - Saurabh Sinha
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Institute of Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- * E-mail: (MHB); (SS)
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44
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Kazemian M, Pham H, Wolfe SA, Brodsky MH, Sinha S. Widespread evidence of cooperative DNA binding by transcription factors in Drosophila development. Nucleic Acids Res 2013; 41:8237-52. [PMID: 23847101 PMCID: PMC3783179 DOI: 10.1093/nar/gkt598] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Regulation of eukaryotic gene transcription is often combinatorial in nature, with multiple transcription factors (TFs) regulating common target genes, often through direct or indirect mutual interactions. Many individual examples of cooperative binding by directly interacting TFs have been identified, but it remains unclear how pervasive this mechanism is during animal development. Cooperative TF binding should be manifest in genomic sequences as biased arrangements of TF-binding sites. Here, we explore the extent and diversity of such arrangements related to gene regulation during Drosophila embryogenesis. We used the DNA-binding specificities of 322 TFs along with chromatin accessibility information to identify enriched spacing and orientation patterns of TF-binding site pairs. We developed a new statistical approach for this task, specifically designed to accurately assess inter-site spacing biases while accounting for the phenomenon of homotypic site clustering commonly observed in developmental regulatory regions. We observed a large number of short-range distance preferences between TF-binding site pairs, including examples where the preference depends on the relative orientation of the binding sites. To test whether these binding site patterns reflect physical interactions between the corresponding TFs, we analyzed 27 TF pairs whose binding sites exhibited short distance preferences. In vitro protein–protein binding experiments revealed that >65% of these TF pairs can directly interact with each other. For five pairs, we further demonstrate that they bind cooperatively to DNA if both sites are present with the preferred spacing. This study demonstrates how DNA-binding motifs can be used to produce a comprehensive map of sequence signatures for different mechanisms of combinatorial TF action.
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Affiliation(s)
- Majid Kazemian
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL, USA, Laboratory of Molecular Immunology and Immunology Center, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA, Program in Gene Function and Expression, University of Massachusetts Medical School, MA, USA, Department of Biochemistry and Molecular Pharmacology University of Massachusetts Medical School, MA, USA, Department of Molecular Medicine, University of Massachusetts Medical School, MA, USA and Institute of Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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45
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Teif VB, Erdel F, Beshnova DA, Vainshtein Y, Mallm JP, Rippe K. Taking into account nucleosomes for predicting gene expression. Methods 2013; 62:26-38. [PMID: 23523656 DOI: 10.1016/j.ymeth.2013.03.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 03/10/2013] [Indexed: 01/10/2023] Open
Abstract
The eukaryotic genome is organized in a chain of nucleosomes that consist of 145-147 bp of DNA wrapped around a histone octamer protein core. Binding of transcription factors (TF) to nucleosomal DNA is frequently impeded, which makes it a challenging task to calculate TF occupancy at a given regulatory genomic site for predicting gene expression. Here, we review methods to calculate TF binding to DNA in the presence of nucleosomes. The main theoretical problems are (i) the computation speed that is becoming a bottleneck when partial unwrapping of DNA from the nucleosome is considered, (ii) the perturbation of the binding equilibrium by the activity of ATP-dependent chromatin remodelers, which translocate nucleosomes along the DNA, and (iii) the model parameterization from high-throughput sequencing data and fluorescence microscopy experiments in living cells. We discuss strategies that address these issues to efficiently compute transcription factor binding in chromatin.
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Affiliation(s)
- Vladimir B Teif
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum-DKFZ & BioQuant, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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46
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Yigit E, Bischof JM, Zhang Z, Ott CJ, Kerschner JL, Leir SH, Buitrago-Delgado E, Zhang Q, Wang JPZ, Widom J, Harris A. Nucleosome mapping across the CFTR locus identifies novel regulatory factors. Nucleic Acids Res 2013; 41:2857-68. [PMID: 23325854 PMCID: PMC3597660 DOI: 10.1093/nar/gks1462] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 12/23/2022] Open
Abstract
Nucleosome positioning on the chromatin strand plays a critical role in regulating accessibility of DNA to transcription factors and chromatin modifying enzymes. Hence, detailed information on nucleosome depletion or movement at cis-acting regulatory elements has the potential to identify predicted binding sites for trans-acting factors. Using a novel method based on enrichment of mononucleosomal DNA by bacterial artificial chromosome hybridization, we mapped nucleosome positions by deep sequencing across 250 kb, encompassing the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR shows tight tissue-specific regulation of expression, which is largely determined by cis-regulatory elements that lie outside the gene promoter. Although multiple elements are known, the repertoire of transcription factors that interact with these sites to activate or repress CFTR expression remains incomplete. Here, we show that specific nucleosome depletion corresponds to well-characterized binding sites for known trans-acting factors, including hepatocyte nuclear factor 1, Forkhead box A1 and CCCTC-binding factor. Moreover, the cell-type selective nucleosome positioning is effective in predicting binding sites for novel interacting factors, such as BAF155. Finally, we identify transcription factor binding sites that are overrepresented in regions where nucleosomes are depleted in a cell-specific manner. This approach recognizes the glucocorticoid receptor as a novel trans-acting factor that regulates CFTR expression in vivo.
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Affiliation(s)
- Erbay Yigit
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Jared M. Bischof
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Zhaolin Zhang
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Christopher J. Ott
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Jenny L. Kerschner
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Shih-Hsing Leir
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Elsy Buitrago-Delgado
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Quanwei Zhang
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Ji-Ping Z. Wang
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Jonathan Widom
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Ann Harris
- Human Molecular Genetics Program, Children’s Memorial Research Center, Department of Pediatrics, Northwestern University Feinberg School of Medicine Chicago, IL 60614, USA, Department of Molecular Biosciences and Department of Statistics, Northwestern University, Evanston, IL 60208, USA
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47
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Babbitt GA, Schulze KV. Codons support the maintenance of intrinsic DNA polymer flexibility over evolutionary timescales. Genome Biol Evol 2012; 4:954-65. [PMID: 22936074 PMCID: PMC3468960 DOI: 10.1093/gbe/evs073] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2012] [Indexed: 01/02/2023] Open
Abstract
Despite our long familiarity with how the genetic code specifies the amino acid sequence, we still know little about why it is organized in the way that it is. Contrary to the view that the organization of the genetic code is a "frozen accident" of evolution, recent studies have demonstrated that it is highly nonrandom, with implications for both codon assignment and usage. We hypothesize that this inherent nonrandomness may facilitate the coexistence of both sequence and structural information in DNA. Here, we take advantage of a simple metric of intrinsic DNA flexibility to analyze mutational effects on the four phosphate linkages present in any given codon. Application of a simple evolutionary neutral model of substitution to random sequences, translated with alternative genetic codes, reveals that the standard code is highly optimized to favor synonymous substitutions that maximize DNA polymer flexibility, potentially counteracting neutral evolutionary drift toward stiffer DNA caused by spontaneous deamination. Comparison to existing mutational patterns in yeast also demonstrates evidence of strong selective constraint on DNA flexibility, especially at so-called "silent" sites. We also report a fundamental relationship between DNA flexibility, codon usage bias, and several important evolutionary descriptors of comparative genomics (e.g., base composition, transition/transversion ratio, and nonsynonymous vs. synonymous substitution rate). Recent advances in structural genomics have emphasized the role of the DNA polymer's flexibility in both gene function and whole genome folding, thereby implicating possible reasons for codons to facilitate the multiplexing of both genetic and structural information within the same molecular context.
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Affiliation(s)
- G A Babbitt
- TH Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, USA.
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48
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Lelli KM, Slattery M, Mann RS. Disentangling the many layers of eukaryotic transcriptional regulation. Annu Rev Genet 2012; 46:43-68. [PMID: 22934649 DOI: 10.1146/annurev-genet-110711-155437] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Regulation of gene expression in eukaryotes is an extremely complex process. In this review, we break down several critical steps, emphasizing new data and techniques that have expanded current gene regulatory models. We begin at the level of DNA sequence where cis-regulatory modules (CRMs) provide important regulatory information in the form of transcription factor (TF) binding sites. In this respect, CRMs function as instructional platforms for the assembly of gene regulatory complexes. We discuss multiple mechanisms controlling complex assembly, including cooperative DNA binding, combinatorial codes, and CRM architecture. The second section of this review places CRM assembly in the context of nucleosomes and condensed chromatin. We discuss how DNA accessibility and histone modifications contribute to TF function. Lastly, new advances in chromosomal mapping techniques have provided increased understanding of intra- and interchromosomal interactions. We discuss how these topological maps influence gene regulatory models.
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Affiliation(s)
- Katherine M Lelli
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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49
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Sterols regulate 3β-hydroxysterol Δ24-reductase (DHCR24) via dual sterol regulatory elements: cooperative induction of key enzymes in lipid synthesis by Sterol Regulatory Element Binding Proteins. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1350-60. [PMID: 22809995 DOI: 10.1016/j.bbalip.2012.07.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/25/2012] [Accepted: 07/09/2012] [Indexed: 01/28/2023]
Abstract
3β-Hydroxysterol Δ24-reductase (DHCR24) catalyzes a final step in cholesterol synthesis, and has been ascribed diverse functions, such as being anti-apoptotic and anti-inflammatory. How this enzyme is regulated transcriptionally by sterols is currently unclear. Some studies have suggested that its expression is regulated by Sterol Regulatory Element Binding Proteins (SREBPs) while another suggests it is through the Liver X Receptor (LXR). However, these transcription factors have opposing effects on cellular sterol levels, so it is likely that one predominates. Here we establish that sterol regulation of DHCR24 occurs predominantly through SREBP-2, and identify the particular region of the DHCR24 promoter to which SREBP-2 binds. We demonstrate that sterol regulation is mediated by two sterol regulatory elements (SREs) in the promoter of the gene, assisted by two nearby NF-Y binding sites. Moreover, we present evidence that the dual SREs work cooperatively to regulate DHCR24 expression by comparison to two known SREBP target genes, the LDL receptor with one SRE, and farnesyl-diphosphate farnesyltransferase 1, with two SREs.
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50
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Winkler DD, Muthurajan UM, Hieb AR, Luger K. Histone chaperone FACT coordinates nucleosome interaction through multiple synergistic binding events. J Biol Chem 2011; 286:41883-41892. [PMID: 21969370 PMCID: PMC3308894 DOI: 10.1074/jbc.m111.301465] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 09/28/2011] [Indexed: 12/21/2022] Open
Abstract
In eukaryotic cells, DNA maintenance requires ordered disassembly and re-assembly of chromatin templates. These processes are highly regulated and require extrinsic factors such as chromatin remodelers and histone chaperones. The histone chaperone FACT (facilitates chromatin transcription) is a large heterodimeric complex with roles in transcription, replication, and repair. FACT promotes and subsequently restricts access to DNA as a result of dynamic nucleosome reorganization. However, until now, there lacked a truly quantitative assessment of the critical contacts mediating FACT function. Here, we demonstrate that FACT binds histones, DNA, and intact nucleosomes at nanomolar concentrations. We also determine roles for the histone tails in free histone and nucleosome binding by FACT. Furthermore, we propose that the conserved acidic C-terminal domain of the FACT subunit Spt16 actively displaces nucleosomal DNA to provide access to the histone octamer. Experiments with tri-nucleosome arrays indicate a possible mode for FACT binding within chromatin. Together, the data reveal that specific FACT subunits synchronize interactions with various target sites on individual nucleosomes to generate a high affinity binding event and promote reorganization.
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Affiliation(s)
- Duane D Winkler
- Howard Hughes Medical Institute and the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870
| | - Uma M Muthurajan
- Howard Hughes Medical Institute and the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870
| | - Aaron R Hieb
- Howard Hughes Medical Institute and the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870
| | - Karolin Luger
- Howard Hughes Medical Institute and the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870.
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