51
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The Role of Nucleosomes in Epigenetic Gene Regulation. Clin Epigenetics 2019. [DOI: 10.1007/978-981-13-8958-0_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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52
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Schlesinger S, Meshorer E. Open Chromatin, Epigenetic Plasticity, and Nuclear Organization in Pluripotency. Dev Cell 2019; 48:135-150. [DOI: 10.1016/j.devcel.2019.01.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/30/2018] [Accepted: 12/31/2018] [Indexed: 12/27/2022]
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53
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Single-cell and single-molecule epigenomics to uncover genome regulation at unprecedented resolution. Nat Genet 2018; 51:19-25. [DOI: 10.1038/s41588-018-0290-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 08/30/2018] [Indexed: 12/19/2022]
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54
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Brahma S, Henikoff S. RSC-Associated Subnucleosomes Define MNase-Sensitive Promoters in Yeast. Mol Cell 2018; 73:238-249.e3. [PMID: 30554944 PMCID: PMC6475595 DOI: 10.1016/j.molcel.2018.10.046] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 09/04/2018] [Accepted: 10/30/2018] [Indexed: 02/07/2023]
Abstract
The classic view of nucleosome organization at active promoters is that two well-positioned nucleosomes flank a nucleosome-depleted region (NDR). However, this view has been recently disputed by contradictory reports as to whether wider (≳150 bp) NDRs instead contain unstable, micrococcal nuclease-sensitive ("fragile") nucleosomal particles. To determine the composition of fragile particles, we introduce CUT&RUN.ChIP, in which targeted nuclease cleavage and release is followed by chromatin immunoprecipitation. We find that fragile particles represent the occupancy of the RSC (remodeling the structure of chromatin) nucleosome remodeling complex and RSC-bound, partially unwrapped nucleosomal intermediates. We also find that general regulatory factors (GRFs) bind to partially unwrapped nucleosomes at these promoters. We propose that RSC binding and its action cause nucleosomes to unravel, facilitate subsequent binding of GRFs, and constitute a dynamic cycle of nucleosome deposition and clearance at the subset of wide Pol II promoter NDRs.
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Affiliation(s)
- Sandipan Brahma
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, USA.
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55
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Novel genetic tools for probing individual H3 molecules in each nucleosome. Curr Genet 2018; 65:371-377. [PMID: 30478690 DOI: 10.1007/s00294-018-0910-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/20/2018] [Accepted: 11/22/2018] [Indexed: 10/27/2022]
Abstract
In eukaryotes, genomic DNA is packaged into the nucleus together with histone proteins, forming chromatin. The fundamental repeating unit of chromatin is the nucleosome, a naturally symmetric structure that wraps DNA and is the substrate for numerous regulatory post-translational modifications. However, the biological significance of nucleosomal symmetry until recently had been unexplored. To investigate this issue, we developed an obligate pair of histone H3 heterodimers, a novel genetic tool that allowed us to modulate modification sites on individual H3 molecules within nucleosomes in vivo. We used these constructs for molecular genetic studies, for example demonstrating that H3K36 methylation on a single H3 molecule per nucleosome in vivo is sufficient to restrain cryptic transcription. We also used asymmetric nucleosomes for mass spectrometric analysis of dependency relationships among histone modifications. Furthermore, we extended this system to the centromeric H3 isoform (Cse4/CENP-A), gaining insights into centromeric nucleosomal symmetry and structure. In this review, we summarize our findings and discuss the utility of this novel approach.
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56
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Heck C, Michaeli Y, Bald I, Ebenstein Y. Analytical epigenetics: single-molecule optical detection of DNA and histone modifications. Curr Opin Biotechnol 2018; 55:151-158. [PMID: 30326408 DOI: 10.1016/j.copbio.2018.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/12/2018] [Accepted: 09/16/2018] [Indexed: 12/13/2022]
Abstract
The field of epigenetics describes the relationship between genotype and phenotype, by regulating gene expression without changing the canonical base sequence of DNA. It deals with molecular genomic information that is encoded by a rich repertoire of chemical modifications and molecular interactions. This regulation involves DNA, RNA and proteins that are enzymatically tagged with small molecular groups that alter their physical and chemical properties. It is now clear that epigenetic alterations are involved in development and disease, and thus, are the focus of intensive research. The ability to record epigenetic changes and quantify them in rare medical samples is critical for next generation diagnostics. Optical detection offers the ultimate single-molecule sensitivity and the potential for spectral multiplexing. Here we review recent progress in ultrasensitive optical detection of DNA and histone modifications.
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Affiliation(s)
- Christian Heck
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel; Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Yael Michaeli
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ilko Bald
- Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany; BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Str. 11, 12489 Berlin, Germany.
| | - Yuval Ebenstein
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel.
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57
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Cao H, Wahlestedt C, Kapranov P. Strategies to Annotate and Characterize Long Noncoding RNAs: Advantages and Pitfalls. Trends Genet 2018; 34:704-721. [DOI: 10.1016/j.tig.2018.06.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/30/2018] [Accepted: 06/12/2018] [Indexed: 12/21/2022]
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58
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Abstract
Epigenetic complexes regulate chromatin dynamics via binding to and assembling on chromatin. However, the mechanisms of chromatin binding and assembly of epigenetic complexes within cells remain incompletely understood, partly due to technical challenges. Here, we present a new approach termed single-molecule chromatin immunoprecipitation imaging (Sm-ChIPi) that enables to assess the cellular assembly stoichiometry of epigenetic complexes on chromatin. Sm-ChIPi was developed based on chromatin immunoprecipitation followed by single-molecule fluorescence microscopy imaging. In this method, an epigenetic complex subunit fused with a gene coding for a fluorescent protein is stably expressed in its corresponding knockout cells. Nucleosomes associated with epigenetic complexes are isolated from cells at native conditions and incubated with biotinylated antibodies. The resulting complexes are immobilized on a quartz slide that had been passivated and functionalized with NeutrAvidin. Image stacks are then acquired by using single-molecule TIRF microscopy. The individual spots imaged by TIRF microscopy represent single protein-nucleosome complexes. The number of copies of the protein complexes on a nucleosome is inferred from the fluorescence photobleaching measurements. Sm-ChIPi is a sensitive and direct method that can quantify the cellular assembly stoichiometry of epigenetic complexes on chromatin.
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Affiliation(s)
- Roubina Tatavosian
- Department of Chemistry, University of Colorado Denver, Denver, CO, 80217-3364, USA
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Renovated Science Building, Rm 3071, 1151 Arapahoe Street, Denver, CO, 80204, USA.
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59
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Albert M, Huttner WB. Epigenetic and Transcriptional Pre-patterning-An Emerging Theme in Cortical Neurogenesis. Front Neurosci 2018; 12:359. [PMID: 29896084 PMCID: PMC5986960 DOI: 10.3389/fnins.2018.00359] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/08/2018] [Indexed: 01/08/2023] Open
Abstract
Neurogenesis is the process through which neural stem and progenitor cells generate neurons. During the development of the mouse neocortex, stem and progenitor cells sequentially give rise to neurons destined to different cortical layers and then switch to gliogenesis resulting in the generation of astrocytes and oligodendrocytes. Precise spatial and temporal regulation of neural progenitor differentiation is key for the proper formation of the complex structure of the neocortex. Dynamic changes in gene expression underlie the coordinated differentiation program, which enables the cells to generate the RNAs and proteins required at different stages of neurogenesis and across different cell types. Here, we review the contribution of epigenetic mechanisms, with a focus on Polycomb proteins, to the regulation of gene expression programs during mouse neocortical development. Moreover, we discuss the recent emerging concept of epigenetic and transcriptional pre-patterning in neocortical progenitor cells as well as post-transcriptional mechanisms for the fine-tuning of mRNA abundance.
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Affiliation(s)
- Mareike Albert
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Wieland B Huttner
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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60
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Kim K, Park KM, Murray J, Kim K, Ryu SH. Direct Profiling the Post-Translational Modification Codes of a Single Protein Immobilized on a Surface Using Cu-free Click Chemistry. ACS CENTRAL SCIENCE 2018; 4:614-623. [PMID: 29806008 PMCID: PMC5968440 DOI: 10.1021/acscentsci.8b00114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Indexed: 06/08/2023]
Abstract
Combinatorial post-translational modifications (PTMs), which can serve as dynamic "molecular barcodes", have been proposed to regulate distinct protein functions. However, studies of combinatorial PTMs on single protein molecules have been hindered by a lack of suitable analytical methods. Here, we describe erasable single-molecule blotting (eSiMBlot) for combinatorial PTM profiling. This assay is performed in a highly multiplexed manner and leverages the benefits of covalent protein immobilization, cyclic probing with different antibodies, and single molecule fluorescence imaging. Especially, facile and efficient covalent immobilization on a surface using Cu-free click chemistry permits multiple rounds (>10) of antibody erasing/reprobing without loss of antigenicity. Moreover, cumulative detection of coregistered multiple data sets for immobilized single-epitope molecules, such as HA peptide, can be used to increase the antibody detection rate. Finally, eSiMBlot enables direct visualization and quantitative profiling of combinatorial PTM codes at the single-molecule level, as we demonstrate by revealing the novel phospho-codes of ligand-induced epidermal growth factor receptor. Thus, eSiMBlot provides an unprecedentedly simple, rapid, and versatile platform for analyzing the vast number of combinatorial PTMs in biological pathways.
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Affiliation(s)
- Kyung
Lock Kim
- Department of Life Sciences and Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
| | - Kyeng Min Park
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
- Department
of Nanomaterials Science and Engineering, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - James Murray
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
| | - Kimoon Kim
- Department of Life Sciences and Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
| | - Sung Ho Ryu
- Department of Life Sciences and Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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61
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Ma S, Hsieh YP, Ma J, Lu C. Low-input and multiplexed microfluidic assay reveals epigenomic variation across cerebellum and prefrontal cortex. SCIENCE ADVANCES 2018; 4:eaar8187. [PMID: 29675472 PMCID: PMC5906078 DOI: 10.1126/sciadv.aar8187] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/01/2018] [Indexed: 05/20/2023]
Abstract
Extensive effort is under way to survey the epigenomic landscape of primary ex vivo tissues to establish normal reference data and to discern variation associated with disease. The low abundance of some tissue types and the isolation procedure required to generate a homogenous cell population often yield a small quantity of cells for examination. This difficulty is further compounded by the need to profile a myriad of epigenetic marks. Thus, technologies that permit both ultralow input and high throughput are desired. We demonstrate a simple microfluidic technology, SurfaceChIP-seq, for profiling genome-wide histone modifications using as few as 30 to 100 cells per assay and with up to eight assays running in parallel. We applied the technology to profile epigenomes using nuclei isolated from prefrontal cortex and cerebellum of mouse brain. Our cell type-specific data revealed that neuronal and glial fractions exhibited profound epigenomic differences across the two functionally distinct brain regions.
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Affiliation(s)
- Sai Ma
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Yuan-Pang Hsieh
- Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Jian Ma
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Chang Lu
- Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
- Corresponding author.
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62
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Abstract
Nucleosomes are the fundamental unit of eukaryotic chromosome packaging, comprised of 147 bp of DNA wrapped around two molecules of each of the core histone proteins H2A, H2B, H3, and H4. Nucleosomes are symmetrical, with one axis of symmetry centered on the homodimeric interaction between the C-termini of the H3 molecules. To explore the functional consequences of nucleosome symmetry, we designed an obligate pair of H3 heterodimers, termed H3X and H3Y, allowing us to compare cells with single or double H3 alterations. Our biochemical validation of the heterodimeric X-Y interaction included intra-nucleosomal H3 crosslinking using dimethyl suberimidate (DMS). Here, we provide a detailed protocol for the use of DMS to analyze yeast nucleosomes.
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Affiliation(s)
- Yuichi Ichiakwa
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Paul D Kaufman
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
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63
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Marinov GK, Kundaje A. ChIP-ping the branches of the tree: functional genomics and the evolution of eukaryotic gene regulation. Brief Funct Genomics 2018; 17:116-137. [PMID: 29529131 PMCID: PMC5889016 DOI: 10.1093/bfgp/ely004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Advances in the methods for detecting protein-DNA interactions have played a key role in determining the directions of research into the mechanisms of transcriptional regulation. The most recent major technological transformation happened a decade ago, with the move from using tiling arrays [chromatin immunoprecipitation (ChIP)-on-Chip] to high-throughput sequencing (ChIP-seq) as a readout for ChIP assays. In addition to the numerous other ways in which it is superior to arrays, by eliminating the need to design and manufacture them, sequencing also opened the door to carrying out comparative analyses of genome-wide transcription factor occupancy across species and studying chromatin biology in previously less accessible model and nonmodel organisms, thus allowing us to understand the evolution and diversity of regulatory mechanisms in unprecedented detail. Here, we review the biological insights obtained from such studies in recent years and discuss anticipated future developments in the field.
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Affiliation(s)
- Georgi K Marinov
- Corresponding author: Georgi K. Marinov, Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA. E-mail:
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64
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Evidence for the implication of the histone code in building the genome structure. Biosystems 2018; 164:49-59. [DOI: 10.1016/j.biosystems.2017.11.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 12/13/2022]
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65
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Sazer S, Schiessel H. The biology and polymer physics underlying large-scale chromosome organization. Traffic 2018; 19:87-104. [PMID: 29105235 PMCID: PMC5846894 DOI: 10.1111/tra.12539] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/31/2017] [Accepted: 10/31/2017] [Indexed: 12/21/2022]
Abstract
Chromosome large-scale organization is a beautiful example of the interplay between physics and biology. DNA molecules are polymers and thus belong to the class of molecules for which physicists have developed models and formulated testable hypotheses to understand their arrangement and dynamic properties in solution, based on the principles of polymer physics. Biologists documented and discovered the biochemical basis for the structure, function and dynamic spatial organization of chromosomes in cells. The underlying principles of chromosome organization have recently been revealed in unprecedented detail using high-resolution chromosome capture technology that can simultaneously detect chromosome contact sites throughout the genome. These independent lines of investigation have now converged on a model in which DNA loops, generated by the loop extrusion mechanism, are the basic organizational and functional units of the chromosome.
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Affiliation(s)
- Shelley Sazer
- Verna and Marrs McLean Department of Biochemistry and Molecular BiologyBaylor College of MedicineHoustonTexas
| | - Helmut Schiessel
- Institute Lorentz for Theoretical PhysicsLeiden UniversityLeidenThe Netherlands
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66
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Schlesinger S, Kaffe B, Melcer S, Aguilera JD, Sivaraman DM, Kaplan T, Meshorer E. A hyperdynamic H3.3 nucleosome marks promoter regions in pluripotent embryonic stem cells. Nucleic Acids Res 2017; 45:12181-12194. [PMID: 29036702 PMCID: PMC5716099 DOI: 10.1093/nar/gkx817] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 09/14/2017] [Indexed: 12/16/2022] Open
Abstract
Histone variants and their chaperones are key regulators of eukaryotic transcription, and are critical for normal development. The histone variant H3.3 has been shown to play important roles in pluripotency and differentiation, and although its genome-wide patterns have been investigated, little is known about the role of its dynamic turnover in transcriptional regulation. To elucidate the role of H3.3 dynamics in embryonic stem cell (ESC) biology, we generated mouse ESC lines carrying a single copy of a doxycycline (Dox)-inducible HA-tagged version of H3.3 and monitored the rate of H3.3 incorporation by ChIP-seq at varying time points following Dox induction, before and after RA-induced differentiation. Comparing H3.3 turnover profiles in ESCs and RA-treated cells, we identified a hyperdynamic H3.3-containing nucleosome at the −1 position in promoters of genes expressed in ESCs. This dynamic nucleosome is restricted and shifted downstream into the +1 position following differentiation. We suggest that histone turnover dynamics provides an additional mechanism involved in expression regulation, and that a hyperdynamic −1 nucleosome marks promoters in ESCs. Our data provide evidence for regional regulation of H3.3 turnover in ESC promoters, and calls for testing, in high resolution, the dynamic behavior of additional histone variants and other structural chromatin proteins.
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Affiliation(s)
- Sharon Schlesinger
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel.,Department of animal science, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Binyamin Kaffe
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel
| | - Shai Melcer
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel
| | - Jose D Aguilera
- Department of animal science, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Divya M Sivaraman
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel
| | - Tommy Kaplan
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel
| | - Eran Meshorer
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel.,The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem 9190401, Israel
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67
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Yang X, Gao L, Zhang S. Comparative pan-cancer DNA methylation analysis reveals cancer common and specific patterns. Brief Bioinform 2017; 18:761-773. [PMID: 27436122 DOI: 10.1093/bib/bbw063] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Indexed: 01/05/2023] Open
Abstract
Abnormal DNA methylation is an important epigenetic regulator involving tumorigenesis. Deciphering cancer common and specific DNA methylation patterns is essential for us to understand the mechanisms of tumor development. The Cancer Genome Atlas (TCGA) project provides a large number of samples of different cancers that enable a pan-cancer study of DNA methylation possible. Here we investigate cancer common and specific DNA methylation patterns among 5480 DNA methylation profiles of 15 cancer types from TCGA. We first define differentially methylated CpG sites (DMCs) in each cancer and then identify 5450 hyper- and 4433 hypomethylated pan-cancer DMCs (PDMCs). Intriguingly, three adjacent hypermethylated PDMC constitute an enhancer region, which potentially regulates two tumor suppressor genes BVES and PRDM1 negatively. Moreover, we identify six distinct motif clusters, which are enriched in hyper- or hypomethylated PDMCs and are associated with several well-known cancer hallmarks. We also observe that PDMCs relate to distinct transcriptional groups. Additionally, 55 hypermethylated and 7 hypomethylated PDMCs are significantly associated with patient survival. Lastly, we find that cancer-specific DMCs are enriched in known cancer genes and cell-type-specific super-enhancers. In summary, this study provides a comprehensive investigation and reveals meaningful cancer common and specific DNA methylation patterns.
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68
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Tycko J, Van MV, Elowitz MB, Bintu L. Advancing towards a global mammalian gene regulation model through single-cell analysis and synthetic biology. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2017. [DOI: 10.1016/j.cobme.2017.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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69
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Lorzadeh A, Bilenky M, Hammond C, Knapp DJHF, Li L, Miller PH, Carles A, Heravi-Moussavi A, Gakkhar S, Moksa M, Eaves CJ, Hirst M. Nucleosome Density ChIP-Seq Identifies Distinct Chromatin Modification Signatures Associated with MNase Accessibility. Cell Rep 2017; 17:2112-2124. [PMID: 27851972 DOI: 10.1016/j.celrep.2016.10.055] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 07/05/2016] [Accepted: 09/12/2016] [Indexed: 12/22/2022] Open
Abstract
Nucleosome position, density, and post-translational modification are widely accepted components of mechanisms regulating DNA transcription but still incompletely understood. We present a modified native ChIP-seq method combined with an analytical framework that allows MNase accessibility to be integrated with histone modification profiles. Application of this methodology to the primitive (CD34+) subset of normal human cord blood cells enabled genomic regions enriched in one versus two nucleosomes marked by histone 3 lysine 4 trimethylation (H3K4me3) and/or histone 3 lysine 27 trimethylation (H3K27me3) to be associated with their transcriptional and DNA methylation states. From this analysis, we defined four classes of promoter-specific profiles and demonstrated that a majority of bivalent marked promoters are heterogeneously marked at a single-cell level in this primitive cell type. Interestingly, extension of this approach to human embryonic stem cells revealed an altered relationship between chromatin modification state and nucleosome content at promoters, suggesting developmental stage-specific organization of histone methylation states.
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Affiliation(s)
- Alireza Lorzadeh
- Department of Microbiology and Immunology, Michael Smith Laboratories Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Misha Bilenky
- Canada's Michael Smith Genome Science Center, BC Cancer Agency Vancouver, BC V5Z 4S6, Canada
| | - Colin Hammond
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - David J H F Knapp
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Luolan Li
- Department of Microbiology and Immunology, Michael Smith Laboratories Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Paul H Miller
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Annaick Carles
- Department of Microbiology and Immunology, Michael Smith Laboratories Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Alireza Heravi-Moussavi
- Canada's Michael Smith Genome Science Center, BC Cancer Agency Vancouver, BC V5Z 4S6, Canada
| | - Sitanshu Gakkhar
- Canada's Michael Smith Genome Science Center, BC Cancer Agency Vancouver, BC V5Z 4S6, Canada
| | - Michelle Moksa
- Department of Microbiology and Immunology, Michael Smith Laboratories Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Connie J Eaves
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada
| | - Martin Hirst
- Department of Microbiology and Immunology, Michael Smith Laboratories Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Canada's Michael Smith Genome Science Center, BC Cancer Agency Vancouver, BC V5Z 4S6, Canada.
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70
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Abstract
Multiple mechanisms of epigenetic control that include DNA methylation, histone modification, noncoding RNAs, and mitotic gene bookmarking play pivotal roles in stringent gene regulation during lineage commitment and maintenance. Experimental evidence indicates that bivalent chromatin domains, i.e., genome regions that are marked by both H3K4me3 (activating) and H3K27me3 (repressive) histone modifications, are a key property of pluripotent stem cells. Bivalency of developmental genes during the G1 phase of the pluripotent stem cell cycle contributes to cell fate decisions. Recently, some cancer types have been shown to exhibit partial recapitulation of bivalent chromatin modifications that are lost along with pluripotency, suggesting a mechanism by which cancer cells reacquire properties that are characteristic of undifferentiated, multipotent cells. This bivalent epigenetic control of oncofetal gene expression in cancer cells may offer novel insights into the onset and progression of cancer and may provide specific and selective options for diagnosis as well as for therapeutic intervention.
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71
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Gibson MD, Gatchalian J, Slater A, Kutateladze TG, Poirier MG. PHF1 Tudor and N-terminal domains synergistically target partially unwrapped nucleosomes to increase DNA accessibility. Nucleic Acids Res 2017; 45:3767-3776. [PMID: 28082396 PMCID: PMC5397176 DOI: 10.1093/nar/gkw1320] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 12/20/2016] [Indexed: 01/17/2023] Open
Abstract
The Tudor domain of human PHF1 recognizes trimethylated lysine 36 on histone H3 (H3K36me3). PHF1 relies on this interaction to regulate PRC2 methyltransferase activity, localize to DNA double strand breaks and mediate nucleosome accessibility. Here, we investigate the impact of the PHF1 N-terminal domain (NTD) on the Tudor domain interaction with the nucleosome. We show that the NTD is partially ordered when it is natively attached to the Tudor domain. Through a combination of FRET and single molecule studies, we find that the increase of DNA accessibility within the H3K36me3-containing nucleosome, instigated by the Tudor binding to H3K36me3, is dramatically enhanced by the NTD. We demonstrate that this nearly order of magnitude increase is due to preferential binding of PHF1 to partially unwrapped nucleosomes, and that PHF1 alters DNA–protein binding within the nucleosome by decreasing dissociation rates. These results highlight the potency of a PTM-binding protein to regulate DNA accessibility and underscores the role of the novel mechanism by which nucleosomes control DNA–protein binding through increasing protein dissociation rates.
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Affiliation(s)
- Matthew D Gibson
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Jovylyn Gatchalian
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Andrew Slater
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Tatiana G Kutateladze
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, 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
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72
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Mauser R, Kungulovski G, Keup C, Reinhardt R, Jeltsch A. Application of dual reading domains as novel reagents in chromatin biology reveals a new H3K9me3 and H3K36me2/3 bivalent chromatin state. Epigenetics Chromatin 2017; 10:45. [PMID: 28946896 PMCID: PMC5613355 DOI: 10.1186/s13072-017-0153-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 09/18/2017] [Indexed: 12/14/2022] Open
Abstract
Background Histone post-translational modifications (PTMs) play central roles in chromatin-templated processes. Combinations of two or more histone PTMs form unique interfaces for readout and recruitment of chromatin interacting complexes, but the genome-wide mapping of coexisting histone PTMs remains an experimentally difficult task. Results We introduce here a novel type of affinity reagents consisting of two fused recombinant histone modification interacting domains (HiMIDs) for direct detection of doubly modified chromatin. To develop the method, we fused the MPP8 chromodomain and DNMT3A PWWP domain which have a binding specificity for H3K9me3 and H3K36me2/3, respectively. We validate the novel reagent biochemically and in ChIP applications and show its specific interaction with H3K9me3–H3K36me2/3 doubly modified chromatin. Modification specificity was confirmed using mutant double-HiMIDs with inactivated methyllysine binding pockets. Using this novel tool, we mapped coexisting H3K9me3–H3K36me2/3 marks in human cells by chromatin interacting domain precipitation (CIDOP). CIDOP-seq data were validated by qPCR, sequential CIDOP/ChIP and by comparison with CIDOP- and ChIP-seq data obtained with single modification readers and antibodies. The genome-wide distribution of H3K9me3–H3K36me2/3 indicates that it represents a novel bivalent chromatin state, which is enriched in weakly transcribed chromatin segments and at ZNF274 and SetDB1 binding sites. Conclusions The application of double-HiMIDs allows the single-step study of co-occurrence and distribution of combinatorial chromatin marks. Our discovery of a novel H3K9me3–H3K36me2/3 bivalent chromatin state illustrates the power of this approach, and it will stimulate numerous follow-up studies on its biological functions. Electronic supplementary material The online version of this article (doi:10.1186/s13072-017-0153-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rebekka Mauser
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569, Stuttgart, Germany
| | - Goran Kungulovski
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569, Stuttgart, Germany
| | - Corinna Keup
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569, Stuttgart, Germany
| | - Richard Reinhardt
- Max-Planck-Genomzentrum Köln, Carl-von-Linné-Weg 10, 50829, Cologne, Germany
| | - Albert Jeltsch
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, Stuttgart University, Allmandring 31, 70569, Stuttgart, Germany.
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73
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Ichikawa Y, Connelly CF, Appleboim A, Miller TC, Jacobi H, Abshiru NA, Chou HJ, Chen Y, Sharma U, Zheng Y, Thomas PM, Chen HV, Bajaj V, Müller CW, Kelleher NL, Friedman N, Bolon DN, Rando OJ, Kaufman PD. A synthetic biology approach to probing nucleosome symmetry. eLife 2017; 6:28836. [PMID: 28895528 PMCID: PMC5626479 DOI: 10.7554/elife.28836] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 09/12/2017] [Indexed: 11/13/2022] Open
Abstract
The repeating subunit of chromatin, the nucleosome, includes two copies of each of the four core histones, and several recent studies have reported that asymmetrically-modified nucleosomes occur at regulatory elements in vivo. To probe the mechanisms by which histone modifications are read out, we designed an obligate pair of H3 heterodimers, termed H3X and H3Y, which we extensively validated genetically and biochemically. Comparing the effects of asymmetric histone tail point mutants with those of symmetric double mutants revealed that a single methylated H3K36 per nucleosome was sufficient to silence cryptic transcription in vivo. We also demonstrate the utility of this system for analysis of histone modification crosstalk, using mass spectrometry to separately identify modifications on each H3 molecule within asymmetric nucleosomes. The ability to generate asymmetric nucleosomes in vivo and in vitro provides a powerful and generalizable tool to probe the mechanisms by which H3 tails are read out by effector proteins in the cell.
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Affiliation(s)
- Yuichi Ichikawa
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
| | - Caitlin F Connelly
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Alon Appleboim
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Thomas Cr Miller
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Hadas Jacobi
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nebiyu A Abshiru
- National Resource for Translational and Developmental Proteomics, Northwestern University, Evanston, United States
| | - Hsin-Jung Chou
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Yuanyuan Chen
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
| | - Upasna Sharma
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Yupeng Zheng
- National Resource for Translational and Developmental Proteomics, Northwestern University, Evanston, United States
| | - Paul M Thomas
- National Resource for Translational and Developmental Proteomics, Northwestern University, Evanston, United States
| | - Hsuiyi V Chen
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Vineeta Bajaj
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
| | - Christoph W Müller
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Neil L Kelleher
- National Resource for Translational and Developmental Proteomics, Northwestern University, Evanston, United States
| | - Nir Friedman
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Daniel Na Bolon
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Oliver J Rando
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Paul D Kaufman
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
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74
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Schuettengruber B, Bourbon HM, Di Croce L, Cavalli G. Genome Regulation by Polycomb and Trithorax: 70 Years and Counting. Cell 2017; 171:34-57. [DOI: 10.1016/j.cell.2017.08.002] [Citation(s) in RCA: 611] [Impact Index Per Article: 87.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/17/2017] [Accepted: 08/01/2017] [Indexed: 01/05/2023]
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75
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The FANTOM5 collection, a data series underpinning mammalian transcriptome atlases in diverse cell types. Sci Data 2017; 4:170113. [PMID: 28850107 PMCID: PMC5574373 DOI: 10.1038/sdata.2017.113] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 07/14/2017] [Indexed: 11/11/2022] Open
Abstract
The latest project from the FANTOM consortium, an international collaborative effort initiated by RIKEN, generated atlases of transcriptomes, in particular promoters, transcribed enhancers, and long-noncoding RNAs, across a diverse set of mammalian cell types. Here, we introduce the FANTOM5 collection, bringing together data descriptors, articles and analyses of FANTOM5 data published across the Nature Research journals. Associated data are openly available for reuse by all.
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76
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Jukam D, Shariati SAM, Skotheim JM. Zygotic Genome Activation in Vertebrates. Dev Cell 2017; 42:316-332. [PMID: 28829942 PMCID: PMC5714289 DOI: 10.1016/j.devcel.2017.07.026] [Citation(s) in RCA: 268] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/25/2017] [Accepted: 07/28/2017] [Indexed: 12/12/2022]
Abstract
The first major developmental transition in vertebrate embryos is the maternal-to-zygotic transition (MZT) when maternal mRNAs are degraded and zygotic transcription begins. During the MZT, the embryo takes charge of gene expression to control cell differentiation and further development. This spectacular organismal transition requires nuclear reprogramming and the initiation of RNAPII at thousands of promoters. Zygotic genome activation (ZGA) is mechanistically coordinated with other embryonic events, including changes in the cell cycle, chromatin state, and nuclear-to-cytoplasmic component ratios. Here, we review progress in understanding vertebrate ZGA dynamics in frogs, fish, mice, and humans to explore differences and emphasize common features.
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Affiliation(s)
- David Jukam
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - S Ali M Shariati
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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77
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Atlasi Y, Stunnenberg HG. The interplay of epigenetic marks during stem cell differentiation and development. Nat Rev Genet 2017; 18:643-658. [PMID: 28804139 DOI: 10.1038/nrg.2017.57] [Citation(s) in RCA: 316] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Chromatin, the template for epigenetic regulation, is a highly dynamic entity that is constantly reshaped during early development and differentiation. Epigenetic modification of chromatin provides the necessary plasticity for cells to respond to environmental and positional cues, and enables the maintenance of acquired information without changing the DNA sequence. The mechanisms involve, among others, chemical modifications of chromatin, changes in chromatin constituents and reconfiguration of chromatin interactions and 3D structure. New advances in genome-wide technologies have paved the way towards an integrative view of epigenome dynamics during cell state transitions, and recent findings in embryonic stem cells highlight how the interplay between different epigenetic layers reshapes the transcriptional landscape.
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Affiliation(s)
- Yaser Atlasi
- Department of Molecular Biology, Faculty of Science, Radboud University, 6525 GA Nijmegen, The Netherlands
| | - Hendrik G Stunnenberg
- Department of Molecular Biology, Faculty of Science, Radboud University, 6525 GA Nijmegen, The Netherlands
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78
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Genome-wide identification of autosomal genes with allelic imbalance of chromatin state. PLoS One 2017; 12:e0182568. [PMID: 28796844 PMCID: PMC5552117 DOI: 10.1371/journal.pone.0182568] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/20/2017] [Indexed: 11/19/2022] Open
Abstract
In mammals, monoallelic gene expression can result from X-chromosome inactivation, genomic imprinting, and random monoallelic expression (RMAE). Epigenetic regulation of RMAE is not fully understood. Here we analyze allelic imbalance in chromatin state of autosomal genes using ChIP-seq in a clonal cell line. We identify approximately 3.7% of autosomal genes that show significant differences between chromatin states of two alleles. Allelic regulation is represented among several functional gene categories including histones, chromatin modifiers, and multiple early developmental regulators. Most cases of allelic skew are produced by quantitative differences between two allelic chromatic states that belong to the same gross type (active, silent, or bivalent). Combinations of allelic states of different types are possible but less frequent. When different chromatin marks are skewed on the same gene, their skew is coordinated as a result of quantitative relationships between these marks on each individual allele. Finally, combination of allele-specific densities of chromatin marks is a quantitative predictor of allelic skew in gene expression.
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79
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van der Harst P, de Windt LJ, Chambers JC. Translational Perspective on Epigenetics in Cardiovascular Disease. J Am Coll Cardiol 2017; 70:590-606. [PMID: 28750703 PMCID: PMC5543329 DOI: 10.1016/j.jacc.2017.05.067] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/30/2017] [Accepted: 05/31/2017] [Indexed: 12/19/2022]
Abstract
A plethora of environmental and behavioral factors interact, resulting in changes in gene expression and providing a basis for the development and progression of cardiovascular diseases. Heterogeneity in gene expression responses among cells and individuals involves epigenetic mechanisms. Advancing technology allowing genome-scale interrogation of epigenetic marks provides a rapidly expanding view of the complexity and diversity of the epigenome. In this review, the authors discuss the expanding landscape of epigenetic modifications and highlight their importance for future understanding of disease. The epigenome provides a mechanistic link between environmental exposures and gene expression profiles ultimately leading to disease. The authors discuss the current evidence for transgenerational epigenetic inheritance and summarize the data linking epigenetics to cardiovascular disease. Furthermore, the potential targets provided by the epigenome for the development of future diagnostics, preventive strategies, and therapy for cardiovascular disease are reviewed. Finally, the authors provide some suggestions for future directions.
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Affiliation(s)
- Pim van der Harst
- Departments of Cardiology and Genetics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; Durrer Center for Cardiovascular Research, Netherlands Heart Institute, Utrecht, the Netherlands.
| | - Leon J de Windt
- Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - John C Chambers
- Department of Epidemiology and Biostatistics, Imperial College London, London, United Kingdom; Ealing Hospital NHS Trust, Middlesex, United Kingdom
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80
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Sidoli S, Lu C, Coradin M, Wang X, Karch KR, Ruminowicz C, Garcia BA. Metabolic labeling in middle-down proteomics allows for investigation of the dynamics of the histone code. Epigenetics Chromatin 2017; 10:34. [PMID: 28683815 PMCID: PMC5501349 DOI: 10.1186/s13072-017-0139-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 06/27/2017] [Indexed: 01/15/2023] Open
Abstract
Background Middle-down mass spectrometry (MS), i.e., analysis of long (~50–60 aa) polypeptides, has become the method with the highest throughput and accuracy for the characterization of combinatorial histone posttranslational modifications (PTMs). The discovery of histone readers with multiple domains, and overall the cross talk of PTMs that decorate histone proteins, has revealed that histone marks have synergistic roles in modulating enzyme recruitment and subsequent chromatin activities. Here, we demonstrate that the middle-down MS strategy can be combined with metabolic labeling for enhanced quantification of histone proteins and their combinatorial PTMs in a dynamic manner. Methods We used a nanoHPLC-MS/MS system consisting of hybrid weak cation exchange–hydrophilic interaction chromatography combined with high resolution MS and MS/MS with ETD fragmentation. After spectra identification, we filtered confident hits and quantified polypeptides using our in-house software isoScale. Results We first verified that middle-down MS can discriminate and differentially quantify unlabeled from heavy labeled histone N-terminal tails (heavy lysine and arginine residues). Results revealed no bias toward identifying and quantifying unlabeled versus heavy labeled tails, even if the heavy labeled peptides presented the typical skewed isotopic pattern typical of long protein sequences that hardly get 100% labeling. Next, we plated epithelial cells into a media with heavy methionine-(methyl-13CD3), the precursor of the methyl donor S-adenosylmethionine and stimulated epithelial to mesenchymal transition (EMT). We assessed that results were reproducible across biological replicates and with data obtained using the more widely adopted bottom-up MS strategy, i.e., analysis of short tryptic peptides. We found remarkable differences in the incorporation rate of methylations in non-confluent cells versus confluent cells. Moreover, we showed that H3K27me3 was a critical player during the EMT process, as a consistent portion of histones modified as H3K27me2K36me2 in epithelial cells were converted into H3K27me3K36me2 in mesenchymal cells. Conclusions We demonstrate that middle-down MS, despite being a more scarcely exploited MS technique than bottom-up, is a robust quantitative method for histone PTM characterization. In particular, middle-down MS combined with metabolic labeling is currently the only methodology available for investigating turnover of combinatorial histone PTMs in dynamic systems. Electronic supplementary material The online version of this article (doi:10.1186/s13072-017-0139-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Simone Sidoli
- Department of Biochemistry and Biophysics, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Room 9-124, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104, USA
| | - Congcong Lu
- Department of Biochemistry and Biophysics, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Room 9-124, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104, USA
| | - Mariel Coradin
- Department of Biochemistry and Biophysics, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Room 9-124, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104, USA
| | - Xiaoshi Wang
- Department of Biochemistry and Biophysics, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Room 9-124, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104, USA
| | - Kelly R Karch
- Department of Biochemistry and Biophysics, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Room 9-124, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104, USA
| | | | - Benjamin A Garcia
- Department of Biochemistry and Biophysics, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Room 9-124, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104, USA.
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81
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Abstract
INTRODUCTION Analysis of histone post-translational modifications (PTMs) by mass spectrometry (MS) has become a fundamental tool for the characterization of chromatin composition and dynamics. Histone PTMs benchmark several biological states of chromatin, including regions of active enhancers, active/repressed gene promoters and damaged DNA. These complex regulatory mechanisms are often defined by combinatorial histone PTMs; for instance, active enhancers are commonly occupied by both marks H3K4me1 and H3K27ac. The traditional bottom-up MS strategy identifies and quantifies short (aa 4-20) tryptic peptides, and it is thus not suitable for the characterization of combinatorial PTMs. Areas covered: Here, we review the advancement of the middle-down MS strategy applied to histones, which consists in the analysis of intact histone N-terminal tails (aa 50-60). Middle-down MS has reached sufficient robustness and reliability, and it is far less technically challenging than PTM quantification on intact histones (top-down). However, the very few chromatin biology studies applying middle-down MS resulting from PubMed searches indicate that it is still very scarcely exploited, potentially due to the apparent high complexity of method and analysis. Expert commentary: We will discuss the state-of-the-art workflow and examples of existing studies, aiming to highlight its potential and feasibility for studies of cell biologists interested in chromatin and epigenetics.
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Affiliation(s)
- Simone Sidoli
- a Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine , University of Pennsylvania , Philadelphia , PA , USA
| | - Benjamin A Garcia
- a Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine , University of Pennsylvania , Philadelphia , PA , USA
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82
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Kar G, Kim JK, Kolodziejczyk AA, Natarajan KN, Torlai Triglia E, Mifsud B, Elderkin S, Marioni JC, Pombo A, Teichmann SA. Flipping between Polycomb repressed and active transcriptional states introduces noise in gene expression. Nat Commun 2017; 8:36. [PMID: 28652613 PMCID: PMC5484669 DOI: 10.1038/s41467-017-00052-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 04/28/2017] [Indexed: 11/09/2022] Open
Abstract
Polycomb repressive complexes (PRCs) are important histone modifiers, which silence gene expression; yet, there exists a subset of PRC-bound genes actively transcribed by RNA polymerase II (RNAPII). It is likely that the role of Polycomb repressive complex is to dampen expression of these PRC-active genes. However, it is unclear how this flipping between chromatin states alters the kinetics of transcription. Here, we integrate histone modifications and RNAPII states derived from bulk ChIP-seq data with single-cell RNA-sequencing data. We find that Polycomb repressive complex-active genes have greater cell-to-cell variation in expression than active genes, and these results are validated by knockout experiments. We also show that PRC-active genes are clustered on chromosomes in both two and three dimensions, and interactions with active enhancers promote a stabilization of gene expression noise. These findings provide new insights into how chromatin regulation modulates stochastic gene expression and transcriptional bursting, with implications for regulation of pluripotency and development.Polycomb repressive complexes modify histones but it is unclear how changes in chromatin states alter kinetics of transcription. Here, the authors use single-cell RNAseq and ChIPseq to find that actively transcribed genes with Polycomb marks have greater cell-to-cell variation in expression.
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Affiliation(s)
- Gozde Kar
- European Molecular Biology Laboratory-European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD, UK
| | - Jong Kyoung Kim
- European Molecular Biology Laboratory-European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD, UK
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea
| | - Aleksandra A Kolodziejczyk
- European Molecular Biology Laboratory-European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD, UK
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Kedar Nath Natarajan
- European Molecular Biology Laboratory-European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD, UK
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Elena Torlai Triglia
- Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Robert Roessle Strasse, Berlin-Buch, 13125, Germany
| | - Borbala Mifsud
- Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
- William Harvey Research Institute, Queen Mary University London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Sarah Elderkin
- Nuclear Dynamics Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - John C Marioni
- European Molecular Biology Laboratory-European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD, UK
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Ana Pombo
- Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Robert Roessle Strasse, Berlin-Buch, 13125, Germany
| | - Sarah A Teichmann
- European Molecular Biology Laboratory-European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD, UK.
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
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83
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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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84
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Changes to histone modifications following prenatal alcohol exposure: An emerging picture. Alcohol 2017; 60:41-52. [PMID: 28431792 DOI: 10.1016/j.alcohol.2017.01.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 12/12/2022]
Abstract
Epigenetic mechanisms are important for facilitating gene-environment interactions in many disease etiologies, including Fetal Alcohol Spectrum Disorders (FASD). Extensive research into the role of DNA methylation and miRNAs in animal models has illuminated the complex role of these mechanisms in FASD. In contrast, histone modifications have not been as well researched, due in part to being less stable than DNA methylation and less well-characterized in disease. It is now apparent that even changes in transient marks can have profound effects if they alter developmental trajectories. In addition, many histone methylations are now known to be relatively stable and can propagate themselves. As technologies and knowledge have advanced, a small group has investigated the role of histone modifications in FASD. Here, we synthesize the data on the effects of prenatal alcohol exposure (PAE) on histone modifications. Several key points are evident. AS with most alcohol-induced outcomes, timing and dosage differences yield variable effects. Nevertheless, these studies consistently find enrichment of H3K9ac, H3K27me2,3, and H3K9me2, and increased expression of histone acetyltransferases and methyltransferases. The consistency of these alterations may implicate them as key mechanisms underlying FASD. Histone modification changes do not often correlate with gene expression changes, though some important examples exist. Encouragingly, attempts to reproduce specific histone modification changes are very often successful. We comment on possible directions for future studies, focusing on further exploration of current trends, expansion of time-point and dosage regimes, and evaluation of biomarker potential.
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85
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Abstract
While chromatin characteristics in interphase are widely studied, characteristics of mitotic chromatin and their inheritance through mitosis are still poorly understood. During mitosis, chromatin undergoes dramatic changes: transcription stalls, chromatin-binding factors leave the chromatin, histone modifications change and chromatin becomes highly condensed. Many key insights into mitotic chromosome state and conformation have come from extensive microscopy studies over the last century. Over the last decade, the development of 3C-based techniques has enabled the study of higher order chromosome organization during mitosis in a genome-wide manner. During mitosis, chromosomes lose their cell type-specific and locus-dependent chromatin organization that characterizes interphase chromatin and fold into randomly positioned loop arrays. Upon exit of mitosis, cells are capable of quickly rearranging the chromosome conformation to form the cell type-specific interphase organization again. The information that enables this rearrangement after mitotic exit is thought to be encoded at least in part in mitotic bookmarks, e.g. histone modifications and variants, histone remodelers, chromatin factors, and non-coding RNA. Here we give an overview of the chromosomal organization and epigenetic characteristics of interphase and mitotic chromatin in vertebrates. Second, we describe different ways in which mitotic bookmarking enables epigenetic memory of the features of interphase chromatin through mitosis. And third, we explore the role of epigenetic modifications and mitotic bookmarking in cell differentiation.
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Affiliation(s)
- Marlies E. Oomen
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605-0103, USA
| | - Job Dekker
- Howard Hughes Medical Institute, Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605-0103, USA
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86
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De Gobbi M, Brazel AJ, Sharpe JA, Sloane-Stanley JA, Smith AJ, Wood WG, Vernimmen D. Enhancer deletion generates cellular phenotypic diversity due to bimodal gene expression. Blood Cells Mol Dis 2017; 64:10-12. [PMID: 28292728 DOI: 10.1016/j.bcmd.2017.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 02/25/2017] [Indexed: 11/26/2022]
Affiliation(s)
- Marco De Gobbi
- University of Torino, Department of Clinical and Biological Sciences, AOU San Luigi Gonzaga, Orbassano 10043, Torino, Italy
| | - Ailbhe J Brazel
- The Roslin Institute, Developmental Biology Division, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Jacqueline A Sharpe
- MRC Molecular Haematology Unit, Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Jacqueline A Sloane-Stanley
- MRC Molecular Haematology Unit, Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Andrew J Smith
- MRC Molecular Haematology Unit, Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - William G Wood
- MRC Molecular Haematology Unit, Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Douglas Vernimmen
- The Roslin Institute, Developmental Biology Division, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK.
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87
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Salzberg AC, Harris-Becker A, Popova EY, Keasey N, Loughran TP, Claxton DF, Grigoryev SA. Genome-wide mapping of histone H3K9me2 in acute myeloid leukemia reveals large chromosomal domains associated with massive gene silencing and sites of genome instability. PLoS One 2017; 12:e0173723. [PMID: 28301528 PMCID: PMC5354391 DOI: 10.1371/journal.pone.0173723] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 02/24/2017] [Indexed: 01/05/2023] Open
Abstract
A facultative heterochromatin mark, histone H3 lysine 9 dimethylation (H3K9me2), which is mediated by histone methyltransferases G9a/GLP (EHMT2/1), undergoes dramatic rearrangements during myeloid cell differentiation as observed by chromatin imaging. To determine whether these structural transitions also involve genomic repositioning of H3K9me2, we used ChIP-sequencing to map genome-wide topography of H3K9me2 in normal human granulocytes, normal CD34+ hematopoietic progenitors, primary myeloblasts from acute myeloid leukemia (AML) patients, and a model leukemia cell line K562. We observe that H3K9me2 naturally repositions from the previously designated “repressed” chromatin state in hematopoietic progenitors to predominant association with heterochromatin regions in granulocytes. In contrast, AML cells accumulate H3K9me2 on previously undefined large (> 100 Kb) genomic blocks that are enriched with AML-specific single nucleotide variants, sites of chromosomal translocations, and genes downregulated in AML. Specifically, the AML-specific H3K9me2 blocks are enriched with genes regulated by the proto-oncogene ERG that promotes stem cell characteristics. The AML-enriched H3K9me2 blocks (in contrast to the heterochromatin-associated H3K9me2 blocks enriched in granulocytes) are reduced by pharmacological inhibition of the histone methyltransferase G9a/GLP in K562 cells concomitantly with transcriptional activation of ERG and ETS1 oncogenes. Our data suggest that G9a/GLP mediate formation of transient H3K9me2 blocks that are preserved in AML myeloblasts and may lead to an increased rate of AML-specific mutagenesis and chromosomal translocations.
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Affiliation(s)
- Anna C. Salzberg
- Division of Biostatistics and Bioinformatics and Penn State Institute for Personalized Medicine, Hershey, Pennsylvania, United States of America
| | - Abigail Harris-Becker
- Penn State College of Medicine, Dept. Biochemistry & Molecular Biology, H171, Hershey, Pennsylvania, United States of America
| | - Evgenya Y. Popova
- Penn State College of Medicine, Department of Neural and Behavioral Sciences, Hershey, Pennsylvania, United States of America
| | - Nikki Keasey
- Penn State Cancer Institute; Milton S. Hershey Medical Center, 500 University Drive, Hershey, Pennsylvania, United States of America
| | - Thomas P. Loughran
- University of Virginia Cancer Center, Charlottesville, Virginia, United States of America
| | - David F. Claxton
- Penn State Cancer Institute; Milton S. Hershey Medical Center, 500 University Drive, Hershey, Pennsylvania, United States of America
- * E-mail: (SAG); (DFC)
| | - Sergei A. Grigoryev
- Penn State College of Medicine, Dept. Biochemistry & Molecular Biology, H171, Hershey, Pennsylvania, United States of America
- * E-mail: (SAG); (DFC)
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88
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Histone Post-Translational Modifications and Nucleosome Organisation in Transcriptional Regulation: Some Open Questions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017. [PMID: 28639249 DOI: 10.1007/5584_2017_58] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The organisation of chromatin is first discussed to conclude that nucleosomes play both structural and transcription-regulatory roles. The presence of nucleosomes makes difficult the access of transcriptional factors to their target sequences and the action of RNA polymerases. The histone post-translational modifications and nucleosome remodelling are first discussed, from a historical point of view, as mechanisms to remove the obstacles imposed by chromatin structure to transcription. Instead of reviewing the state of the art of the whole field, this review is centred on some open questions. First, some "non-classical" histone modifications, such as short-chain acylations other than acetylation, are considered to conclude that their relationship with the concentration of metabolic intermediaries might make of them a sensor of the physiological state of the cells. Then attention is paid to the interest of studying chromatin organisation and epigenetic marks at a single nucleosome level as a complement to genome-wide approaches. Finally, as a consequence of the above questions, the review focuses on the presence of multiple histone post-translational modifications on a single nucleosome. The methods to detect them and their meaning, with special emphasis on bivalent marks, are discussed.
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89
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Bayarsaihan D. Deciphering the Epigenetic Code in Embryonic and Dental Pulp Stem Cells. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2016; 89:539-563. [PMID: 28018144 PMCID: PMC5168831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A close cooperation between chromatin states, transcriptional modulation, and epigenetic modifications is required for establishing appropriate regulatory circuits underlying self-renewal and differentiation of adult and embryonic stem cells. A growing body of research has established that the epigenome topology provides a structural framework for engaging genes in the non-random chromosomal interactions to orchestrate complex processes such as cell-matrix interactions, cell adhesion and cell migration during lineage commitment. Over the past few years, the functional dissection of the epigenetic landscape has become increasingly important for understanding gene expression dynamics in stem cells naturally found in most tissues. Adult stem cells of the human dental pulp hold great promise for tissue engineering, particularly in the skeletal and tooth regenerative medicine. It is therefore likely that progress towards pulp regeneration will have a substantial impact on the clinical research. This review summarizes the current state of knowledge regarding epigenetic cues that have evolved to regulate the pluripotent differentiation potential of embryonic stem cells and the lineage determination of developing dental pulp progenitors.
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Affiliation(s)
- Dashzeveg Bayarsaihan
- Institute for System Genomics and Center for Regenerative Medicine and Skeletal Development, University of Connecticut Health Center, Farmington, CT, USA
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90
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Dysregulation of histone methyltransferases in breast cancer - Opportunities for new targeted therapies? Mol Oncol 2016; 10:1497-1515. [PMID: 27717710 DOI: 10.1016/j.molonc.2016.09.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 09/14/2016] [Accepted: 09/14/2016] [Indexed: 01/24/2023] Open
Abstract
Histone methyltransferases (HMTs) catalyze the methylation of lysine and arginine residues on histone tails and non-histone targets. These important post-translational modifications are exquisitely regulated and affect chromatin compaction and transcriptional programs leading to diverse biological outcomes. There is accumulating evidence that genetic alterations of several HMTs impinge on oncogenic or tumor-suppressor functions and influence both cancer initiation and progression. HMTs therefore represent an opportunity for therapeutic targeting in those patients with tumors in which HMTs are dysregulated, to reverse the histone marks and transcriptional programs associated with aggressive tumor behavior. In this review, we describe the known histone methyltransferases and their emerging roles in breast cancer tumorigenesis.
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91
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Single-molecule fluorescence microscopy of native macromolecular complexes. Curr Opin Struct Biol 2016; 41:225-232. [PMID: 27662375 DOI: 10.1016/j.sbi.2016.09.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/06/2016] [Accepted: 09/07/2016] [Indexed: 12/11/2022]
Abstract
Macromolecular complexes consisting of proteins, lipids, and/or nucleic acids are ubiquitous in biological processes. Their composition, stoichiometry, order of assembly, and conformations can be heterogeneous or can change dynamically, making single-molecule studies best suited to measure these properties accurately. Recent single-molecule pull-down and other related approaches have combined the principles of conventional co-immunoprecipitation assay with single-molecule fluorescence microscopy to probe native macromolecular complexes. In this review, we present the advances in single-molecule pull-down methods and biological systems that have been investigated in such semi vivo manner.
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92
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Sadeh R, Launer-Wachs R, Wandel H, Rahat A, Friedman N. Elucidating Combinatorial Chromatin States at Single-Nucleosome Resolution. Mol Cell 2016; 63:1080-8. [PMID: 27496019 PMCID: PMC5031555 DOI: 10.1016/j.molcel.2016.07.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 07/21/2016] [Accepted: 07/25/2016] [Indexed: 11/18/2022]
Abstract
Chromatin immunoprecipitation followed by sequencing (ChIP-seq) has been instrumental to our current view of chromatin structure and function. It allows genome-wide mapping of histone marks, which demarcate biologically relevant domains. However, ChIP-seq is an ensemble measurement reporting the average occupancy of individual marks in a cell population. Consequently, our understanding of the combinatorial nature of chromatin states relies almost exclusively on correlation between the genomic distributions of individual marks. Here, we report the development of combinatorial-iChIP to determine the genome-wide co-occurrence of histone marks at single-nucleosome resolution. By comparing to a null model, we show that certain combinations of overlapping marks (H3K36me3 and H3K79me3) co-occur more frequently than would be expected by chance, while others (H3K4me3 and H3K36me3) do not, reflecting differences in the underlying chromatin pathways. We further use combinatorial-iChIP to illuminate aspects of the Set2-RPD3S pathway. This approach promises to improve our understanding of the combinatorial complexity of chromatin. High-throughput method for mapping the genome-wide co-occurrence of histone marks H3K36me3 and H3K79me3 co-occur more frequently than would be expected by chance Initiating and elongating Pol II-deposited marks co-occur on the same nucleosomes Disruption of RPD3 increases the co-occurrence of H3K36me3 and H3 acetylation
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Affiliation(s)
- Ronen Sadeh
- School of Computer Science and Engineering and Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | - Roee Launer-Wachs
- School of Computer Science and Engineering and Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Hava Wandel
- School of Computer Science and Engineering and Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ayelet Rahat
- School of Computer Science and Engineering and Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Nir Friedman
- School of Computer Science and Engineering and Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA.
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93
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