151
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Wang Y, Liu H, Sun Z. Lamarck rises from his grave: parental environment-induced epigenetic inheritance in model organisms and humans. Biol Rev Camb Philos Soc 2017; 92:2084-2111. [PMID: 28220606 DOI: 10.1111/brv.12322] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 01/12/2017] [Accepted: 01/18/2017] [Indexed: 12/12/2022]
Abstract
Organisms can change their physiological/behavioural traits to adapt and survive in changed environments. However, whether these acquired traits can be inherited across generations through non-genetic alterations has been a topic of debate for over a century. Emerging evidence indicates that both ancestral and parental experiences, including nutrition, environmental toxins, nurturing behaviour, and social stress, can have powerful effects on the physiological, metabolic and cellular functions in an organism. In certain circumstances, these effects can be transmitted across several generations through epigenetic (i.e. non-DNA sequence-based rather than mutational) modifications. In this review, we summarize recent evidence on epigenetic inheritance from parental environment-induced developmental and physiological alterations in nematodes, fruit flies, zebrafish, rodents, and humans. The epigenetic modifications demonstrated to be both susceptible to modulation by environmental cues and heritable, including DNA methylation, histone modification, and small non-coding RNAs, are also summarized. We particularly focus on evidence that parental environment-induced epigenetic alterations are transmitted through both the maternal and paternal germlines and exert sex-specific effects. The thought-provoking data presented here raise fundamental questions about the mechanisms responsible for these phenomena. In particular, the means that define the specificity of the response to parental experience in the gamete epigenome and that direct the establishment of the specific epigenetic change in the developing embryos, as well as in specific tissues in the descendants, remain obscure and require elucidation. More precise epigenetic assessment at both the genome-wide level and single-cell resolution as well as strategies for breeding at relatively sensitive periods of development and manipulation aimed at specific epigenetic modification are imperative for identifying parental environment-induced epigenetic marks across generations. Considering their diverse epigenetic architectures, the conservation and prevalence of the mechanisms underlying epigenetic inheritance in non-mammals require further investigation in mammals. Interpretation of the consequences arising from epigenetic inheritance on organisms and a better understanding of the underlying mechanisms will provide insight into how gene-environment interactions shape developmental processes and physiological functions, which in turn may have wide-ranging implications for human health, and understanding biological adaptation and evolution.
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Affiliation(s)
- Yan Wang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China
| | - Huijie Liu
- Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou 325000, China
| | - Zhongsheng Sun
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China.,Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou 325000, China
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152
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Kalinava N, Ni JZ, Peterman K, Chen E, Gu SG. Decoupling the downstream effects of germline nuclear RNAi reveals that H3K9me3 is dispensable for heritable RNAi and the maintenance of endogenous siRNA-mediated transcriptional silencing in Caenorhabditis elegans. Epigenetics Chromatin 2017; 10:6. [PMID: 28228846 PMCID: PMC5311726 DOI: 10.1186/s13072-017-0114-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/08/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Germline nuclear RNAi in C. elegans is a transgenerational gene-silencing pathway that leads to H3K9 trimethylation (H3K9me3) and transcriptional silencing at the target genes. H3K9me3 induced by either exogenous double-stranded RNA (dsRNA) or endogenous siRNA (endo-siRNA) is highly specific to the target loci and transgenerationally heritable. Despite these features, the role of H3K9me3 in siRNA-mediated transcriptional silencing and inheritance of the silencing state at native target genes is unclear. In this study, we took combined genetic and whole-genome approaches to address this question. RESULTS Here we demonstrate that siRNA-mediated H3K9me3 requires combined activities of three H3K9 histone methyltransferases: MET-2, SET-25, and SET-32. set-32 single, met-2 set-25 double, and met-2 set-25;set-32 triple mutant adult animals all exhibit prominent reductions in H3K9me3 throughout the genome, with met-2 set-25;set-32 mutant worms losing all detectable H3K9me3 signals. Surprisingly, loss of high-magnitude H3K9me3 at the native nuclear RNAi targets has no effect on the transcriptional silencing state. In addition, the exogenous dsRNA-induced transcriptional silencing and heritable RNAi at oma-1, a well-established nuclear RNAi reporter gene, are completely resistant to the loss of H3K9me3. CONCLUSIONS Nuclear RNAi-mediated H3K9me3 in C. elegans requires multiple histone methyltransferases, including MET-2, SET-25, and SET-32. H3K9me3 is not essential for dsRNA-induced heritable RNAi or the maintenance of endo-siRNA-mediated transcriptional silencing in C. elegans. We propose that siRNA-mediated transcriptional silencing in C. elegans can be maintained by an H3K9me3-independent mechanism.
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Affiliation(s)
- Natallia Kalinava
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Julie Zhouli Ni
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Kimberly Peterman
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Esteban Chen
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Sam Guoping Gu
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA.,Nelson Labs A125, 604 Allison Road, Piscataway, NJ 08854 USA
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153
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Toteva T, Mason B, Kanoh Y, Brøgger P, Green D, Verhein-Hansen J, Masai H, Thon G. Establishment of expression-state boundaries by Rif1 and Taz1 in fission yeast. Proc Natl Acad Sci U S A 2017; 114:1093-1098. [PMID: 28096402 PMCID: PMC5293076 DOI: 10.1073/pnas.1614837114] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Shelterin component Rif1 has emerged as a global regulator of the replication-timing program in all eukaryotes examined to date, possibly by modulating the 3D-organization of the genome. In fission yeast a second Shelterin component, Taz1, might share similar functions. Here, we identified unexpected properties for Rif1 and Taz1 by conducting high-throughput genetic screens designed to identify cis- and trans-acting factors capable of creating heterochromatin-euchromatin boundaries in fission yeast. The preponderance of cis-acting elements identified in the screens originated from genomic loci bound by Taz1 and associated with origins of replication whose firing is repressed by Taz1 and Rif1. Boundary formation and gene silencing by these elements required Taz1 and Rif1 and coincided with altered replication timing in the region. Thus, small chromosomal elements sensitive to Taz1 and Rif1 (STAR) could simultaneously regulate gene expression and DNA replication over a large domain, at the edge of which they established a heterochromatin-euchromatin boundary. Taz1, Rif1, and Rif1-associated protein phosphatases Sds21 and Dis2 were each sufficient to establish a boundary when tethered to DNA. Moreover, efficient boundary formation required the amino-terminal domain of the Mcm4 replicative helicase onto which the antagonistic activities of the replication-promoting Dbf4-dependent kinase and Rif1-recruited phosphatases are believed to converge to control replication origin firing. Altogether these observations provide an insight into a coordinated control of DNA replication and organization of the genome into expression domains.
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Affiliation(s)
- Tea Toteva
- Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Bethany Mason
- Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Yutaka Kanoh
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamkitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Peter Brøgger
- Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Daniel Green
- Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Janne Verhein-Hansen
- Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Hisao Masai
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamkitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Geneviève Thon
- Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark;
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154
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Molitor J, Mallm JP, Rippe K, Erdel F. Retrieving Chromatin Patterns from Deep Sequencing Data Using Correlation Functions. Biophys J 2017; 112:473-490. [PMID: 28131315 DOI: 10.1016/j.bpj.2017.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/30/2016] [Accepted: 01/04/2017] [Indexed: 01/31/2023] Open
Abstract
Epigenetic modifications and other chromatin features partition the genome on multiple length scales. They define chromatin domains with distinct biological functions that come in sizes ranging from single modified DNA bases to several megabases in the case of heterochromatic histone modifications. Due to chromatin folding, domains that are well separated along the linear nucleosome chain can form long-range interactions in three-dimensional space. It has now become a routine task to map epigenetic marks and chromatin structure by deep sequencing methods. However, assessing and comparing the properties of chromatin domains and their positional relationships across data sets without a priori assumptions remains challenging. Here, we introduce multiscale correlation evaluation (MCORE), which uses the fluctuation spectrum of mapped sequencing reads to quantify and compare chromatin patterns over a broad range of length scales in a model-independent manner. We applied MCORE to map the chromatin landscape in mouse embryonic stem cells and differentiated neural cells. We integrated sequencing data from chromatin immunoprecipitation, RNA expression, DNA methylation, and chromosome conformation capture experiments into network models that reflect the positional relationships among these features on different genomic scales. Furthermore, we used MCORE to compare our experimental data to models for heterochromatin reorganization during differentiation. The application of correlation functions to deep sequencing data complements current evaluation schemes and will support the development of quantitative descriptions of chromatin networks.
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Affiliation(s)
- Jana Molitor
- German Cancer Research Center (DKFZ) and Bioquant, Research Group Genome Organization & Function, Heidelberg, Germany
| | - Jan-Philipp Mallm
- German Cancer Research Center (DKFZ) and Bioquant, Research Group Genome Organization & Function, Heidelberg, Germany
| | - Karsten Rippe
- German Cancer Research Center (DKFZ) and Bioquant, Research Group Genome Organization & Function, Heidelberg, Germany.
| | - Fabian Erdel
- German Cancer Research Center (DKFZ) and Bioquant, Research Group Genome Organization & Function, Heidelberg, Germany.
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155
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Abstract
Epigenome editing aims for an introduction or removal of chromatin marks at a defined genomic region using artificial EpiEffectors resulting in a modulation of the activity of the targeted functional DNA elements. Rationally designed EpiEffectors consist of a targeting DNA-binding module (such as a zinc finger protein, TAL effector, or CRISPR/Cas complex) and usually, but not exclusively, a catalytic domain of a chromatin-modifying enzyme. Epigenome editing opens a completely new strategy for basic research of the central nervous system and causal treatment of psychiatric and neurological diseases, because rewriting of epigenetic information can lead to the direct and durable control of the expression of disease-associated genes. Here, we review current advances in the design of locus- and allele-specific DNA-binding modules, approaches for spatial, and temporal control of EpiEffectors and discuss some examples of existing and propose new potential therapeutic strategies based on epigenome editing for treatment of neurodegenerative and psychiatric diseases. These include the targeted silencing of disease-associated genes or activation of neuroprotective genes which may be applied in Alzheimer's and Parkinson's diseases or the control of addiction and depression. Moreover, we discuss allele-specific epigenome editing as novel therapeutic approach for imprinting disorders, Huntington's disease and Rett syndrome.
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156
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Alabert C, Jasencakova Z, Groth A. Chromatin Replication and Histone Dynamics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:311-333. [PMID: 29357065 DOI: 10.1007/978-981-10-6955-0_15] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Inheritance of the DNA sequence and its proper organization into chromatin is fundamental for genome stability and function. Therefore, how specific chromatin structures are restored on newly synthesized DNA and transmitted through cell division remains a central question to understand cell fate choices and self-renewal. Propagation of genetic information and chromatin-based information in cycling cells entails genome-wide disruption and restoration of chromatin, coupled with faithful replication of DNA. In this chapter, we describe how cells duplicate the genome while maintaining its proper organization into chromatin. We reveal how specialized replication-coupled mechanisms rapidly assemble newly synthesized DNA into nucleosomes, while the complete restoration of chromatin organization including histone marks is a continuous process taking place throughout the cell cycle. Because failure to reassemble nucleosomes at replication forks blocks DNA replication progression in higher eukaryotes and leads to genomic instability, we further underline the importance of the mechanistic link between DNA replication and chromatin duplication.
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Affiliation(s)
- Constance Alabert
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
| | - Zuzana Jasencakova
- Biotech Research and Innovation Centre (BRIC), Health and Medical Faculty, University of Copenhagen, Copenhagen, Denmark
| | - Anja Groth
- Biotech Research and Innovation Centre (BRIC), Health and Medical Faculty, University of Copenhagen, Copenhagen, Denmark.
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157
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Cam HP, Whitehall S. Analysis of Heterochromatin in Schizosaccharomyces pombe. Cold Spring Harb Protoc 2016; 2016:2016/11/pdb.top079889. [PMID: 27803258 DOI: 10.1101/pdb.top079889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This introduction briefly describes the biology of heterochromatin in the fission yeast Schizosaccharomyces pombe We highlight some of the salient features of fission yeast that render it an excellent unicellular eukaryote for studying heterochromatin. We then discuss key aspects of heterochromatin that are of interest to those in the field, and last we introduce experimental approaches often used to investigate heterochromatin.
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Affiliation(s)
- Hugh P Cam
- Biology Department, Boston College, Chestnut Hill, Massachusetts 02467
| | - Simon Whitehall
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle NE2 4HH, United Kingdom
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158
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Braun S, Barrales RR. Beyond Tethering and the LEM domain: MSCellaneous functions of the inner nuclear membrane Lem2. Nucleus 2016; 7:523-531. [PMID: 27797637 DOI: 10.1080/19491034.2016.1252892] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The nuclear envelope plays a pivotal role in the functional organization of chromatin. Various inner nuclear membrane (INM) proteins associate with transcriptionally repressed chromatin, which is often found at the nuclear periphery. A prominent example is the conserved family of LEM (LAP2-Emerin-MAN1) domain proteins that interact with DNA-binding proteins and have been proposed to mediate tethering of chromatin to the nuclear membrane. We recently reported that the fission yeast protein Lem2, a homolog of metazoan LEM proteins, contributes to perinuclear localization and silencing of heterochromatin. 1 We demonstrate that binding and tethering of centromeric chromatin depends on the LEM domain of Lem2. Unexpectedly, this domain is dispensable for heterochromatin silencing, which is instead mediated by a different structural domain of Lem2, the MSC (MAN1-Src1 C-terminal) domain. Hence, silencing and tethering by Lem2 can be mechanistically separated. Notably, the MSC domain has multiple functions beyond heterochromatic silencing. Here we discuss the implications of these novel findings for the understanding of this conserved INM protein.
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Affiliation(s)
- Sigurd Braun
- a Department of Physiological Chemistry , Biomedical Center (BMC), Ludwig-Maximilians-University of Munich , Martinsried , Germany
| | - Ramón Ramos Barrales
- a Department of Physiological Chemistry , Biomedical Center (BMC), Ludwig-Maximilians-University of Munich , Martinsried , Germany.,b Present address: Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide, Sevilla-CSIC-Junta de Andalucía , Sevilla , Spain
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159
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Brueckner L, van Arensbergen J, Akhtar W, Pagie L, van Steensel B. High-throughput assessment of context-dependent effects of chromatin proteins. Epigenetics Chromatin 2016; 9:43. [PMID: 27777628 PMCID: PMC5069885 DOI: 10.1186/s13072-016-0096-y] [Citation(s) in RCA: 12] [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: 09/15/2016] [Accepted: 09/27/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chromatin proteins control gene activity in a concerted manner. We developed a high-throughput assay to study the effects of the local chromatin environment on the regulatory activity of a protein of interest. The assay combines a previously reported multiplexing strategy based on barcoded randomly integrated reporters with Gal4-mediated tethering. We applied the assay to Drosophila heterochromatin protein 1a (HP1a), which is mostly known as a repressive protein but has also been linked to transcriptional activation. RESULTS Recruitment to over 1000 genomic locations revealed that HP1a is a potent repressor able to silence even highly expressing reporter genes. However, the local chromatin context can modulate HP1a function. In pericentromeric regions, HP1a-induced repression was enhanced by twofold. In regions marked by a H3K36me3-rich chromatin signature, HP1a-dependent silencing was significantly decreased. We found no evidence for an activating function of HP1a in our experimental system. Furthermore, we did not observe stable transmission of repression over mitotic divisions after loss of targeted HP1a. CONCLUSIONS The multiplexed tethered reporter assay should be applicable to a large number of chromatin proteins and will be a useful tool to dissect combinatorial regulatory interactions in chromatin.
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Affiliation(s)
- Laura Brueckner
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Joris van Arensbergen
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Waseem Akhtar
- Division of Molecular Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Ludo Pagie
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Bas van Steensel
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, The Netherlands
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, The Netherlands
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160
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Bell CG. Insights in human epigenomic dynamics through comparative primate analysis. Genomics 2016; 108:115-125. [DOI: 10.1016/j.ygeno.2016.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 08/03/2016] [Accepted: 09/29/2016] [Indexed: 12/11/2022]
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161
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Shan CM, Wang J, Xu K, Chen H, Yue JX, Andrews S, Moresco JJ, Yates JR, Nagy PL, Tong L, Jia S. A histone H3K9M mutation traps histone methyltransferase Clr4 to prevent heterochromatin spreading. eLife 2016; 5. [PMID: 27648579 PMCID: PMC5030085 DOI: 10.7554/elife.17903] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 08/22/2016] [Indexed: 01/07/2023] Open
Abstract
Histone lysine-to-methionine (K-to-M) mutations are associated with multiple cancers, and they function in a dominant fashion to block the methylation of corresponding lysines on wild type histones. However, their mechanisms of function are controversial. Here we show that in fission yeast, introducing the K9M mutation into one of the three histone H3 genes dominantly blocks H3K9 methylation on wild type H3 across the genome. In addition, H3K9M enhances the interaction of histone H3 tail with the H3K9 methyltransferase Clr4 in a SAM (S-adenosyl-methionine)-dependent manner, and Clr4 is trapped at nucleation sites to prevent its spreading and the formation of large heterochromatin domains. We further determined the crystal structure of an H3K9M peptide in complex with human H3K9 methyltransferase G9a and SAM, which reveales that the methionine side chain had enhanced van der Waals interactions with G9a. Therefore, our results provide a detailed mechanism by which H3K9M regulates H3K9 methylation. DOI:http://dx.doi.org/10.7554/eLife.17903.001 Cells switch their genes on or off in order to respond to changes in their environment. A group of proteins called histones are partly responsible for regulating gene activity. Like all proteins, histones are made from smaller building blocks called amino acids. Enzymes can chemically modify specific amino acids in histone proteins, which allows the histones to switch nearby genes on or off. One of these modifications is called methylation, and the methylation of specific “lysine” amino acids in histone proteins regulates gene activity in different ways. Previous research has shown that, in certain types of cancer cells, lysines that can be methylated are often replaced with another amino acid, a methionine. These substitutions stop the histones from correctly controlling the activity of nearby genes because methionine cannot be methylated like lysine. Additionally, even if only a small number of histones have methionine in place of lysine, this change can have a widespread effect because the few histones with the methionine can block other histones from being methylated too. However, previous studies did not provide a clear mechanism for why this is the case. In the fission yeast Schizosaccharomyces pombe an enzyme called Clr4 methylates a histone protein at a lysine named H3K9. Now, Shan, Wang, Xu et al. show that substituting this lysine with a methionine (referred to as H3K9M) stops the widespread methylation of histones by trapping the Clr4 enzyme. Specifically, Clr4 becomes stuck to the H3K9M histones, and is therefore unable to modify any other histones. Shan et al. went on to carry out a more detailed study of the structure of H3K9M attached to another enzyme called G9a. This enzyme is found in human cells and is similarly inhibited by H3K9M. This investigation identified additional chemical interactions that explain why Clr4 and G9a become trapped by the H3K9M histone but not by normal histones. Future studies are needed to explore whether other altered histones are able to trap enzymes in the way that H3K9M traps Clr4 and G9a. In addition, this work could eventually lead to new cancer therapies. DOI:http://dx.doi.org/10.7554/eLife.17903.002
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Affiliation(s)
- Chun-Min Shan
- Department of Biological Sciences, Columbia University, New York, United States
| | - Jiyong Wang
- Department of Biological Sciences, Columbia University, New York, United States
| | - Ke Xu
- Department of Biological Sciences, Columbia University, New York, United States
| | - Huijie Chen
- Department of Pathology, Columbia University, New York, United States
| | - Jia-Xing Yue
- Institute for Research on Cancer and Aging, Nice (IRCAN), CNRS UMR 7284, INSERM U1081, Nice, France
| | - Stuart Andrews
- Department of Pathology, Columbia University, New York, United States
| | - James J Moresco
- Department of Chemical Physiology, Scripps Research Institute, La Jolla, United States
| | - John R Yates
- Department of Chemical Physiology, Scripps Research Institute, La Jolla, United States
| | - Peter L Nagy
- Department of Pathology, Columbia University, New York, United States
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, United States
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, United States
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162
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Kang MK, Mehrazarin S, Park NH, Wang CY. Epigenetic gene regulation by histone demethylases: emerging role in oncogenesis and inflammation. Oral Dis 2016; 23:709-720. [PMID: 27514027 DOI: 10.1111/odi.12569] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/05/2016] [Accepted: 08/09/2016] [Indexed: 12/11/2022]
Abstract
Histone N-terminal tails of nucleosomes are the sites of complex regulation of gene expression through post-translational modifications. Among these modifications, histone methylation had long been associated with permanent gene inactivation until the discovery of Lys-specific demethylase (LSD1), which is responsible for dynamic gene regulation. There are more than 30 members of the Lys demethylase (KDM) family, and with exception of LSD1 and LSD2, all other KDMs possess the Jumonji C (JmjC) domain exhibiting demethylase activity and require unique cofactors, for example, Fe(II) and α-ketoglutarate. These cofactors have been targeted when devising KDM inhibitors, which may yield therapeutic benefit. KDMs and their counterpart Lys methyltransferases (KMTs) regulate multiple biological processes, including oncogenesis and inflammation. KDMs' functional interactions with retinoblastoma (Rb) and E2 factor (E2F) target promoters illustrate their regulatory role in cell cycle progression and oncogenesis. Recent findings also demonstrate the control of inflammation and immune functions by KDMs, such as KDM6B that regulates the pro-inflammatory gene expression and CD4+ T helper (Th) cell lineage determination. This review will highlight the mechanisms by which KDMs and KMTs regulate the target gene expression and how epigenetic mechanisms may be applied to our understanding of oral inflammation.
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Affiliation(s)
- M K Kang
- Shapiro Laboratory of Viral Oncology and Aging Research, Los Angeles, CA, USA
| | - S Mehrazarin
- Shapiro Laboratory of Viral Oncology and Aging Research, Los Angeles, CA, USA
| | - N-H Park
- Shapiro Laboratory of Viral Oncology and Aging Research, Los Angeles, CA, USA.,David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - C-Y Wang
- Laboratory of Molecular Signaling, UCLA School of Dentistry, Los Angeles, CA, USA
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163
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Abstract
We are entering an era of epigenome engineering. The precision manipulation of chromatin and epigenetic modifications provides new ways to interrogate their influence on genome and cell function and to harness these changes for applications. We review the design and state of epigenome editing tools, highlighting the unique regulatory properties afforded by these systems.
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Affiliation(s)
- Minhee Park
- Department of Biomedical Engineering and Biological Design Center, Boston University, Boston, MA, 02215, USA
| | - Albert J Keung
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, 27695, USA
| | - Ahmad S Khalil
- Department of Biomedical Engineering and Biological Design Center, Boston University, Boston, MA, 02215, USA. .,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.
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164
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Abstract
The yeast HO endonuclease is expressed in late G1 in haploid mother cells to initiate mating-type interconversion. Cells can be arrested in G1 by nutrient deprivation or by pheromone exposure, but cells that resume cycling after nutrient deprivation or cyclin-dependent kinase (CDK) inactivation express HO in the first cell cycle, whereas HO is not expressed until the second cycle after release from pheromone arrest. Here, we show that transcription of a long noncoding RNA (lncRNA) mediates this differential response. The SBF and Mediator factors remain bound to the inactive promoter during arrest due to CDK inactivation, and these bound factors allow the cell to remember a transcriptional decision made before arrest. If the presence of mating pheromone indicates that this decision is no longer appropriate, a lncRNA originating at -2700 upstream of the HO gene is induced, and the transcription machinery displaces promoter-bound SBF, preventing HO transcription in the subsequent cell cycle. Further, we find that the displaced SBF is blocked from rebinding due to incorporation of its recognition sites within nucleosomes. Expressing the pHO-lncRNA in trans is ineffective, indicating that transcription in cis is required. Factor displacement during lncRNA transcription could be a general mechanism for regulating memory of previous events at promoters.
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165
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Al-Sady B, Greenstein RA, El-Samad HJ, Braun S, Madhani HD. Sensitive and Quantitative Three-Color Protein Imaging in Fission Yeast Using Spectrally Diverse, Recoded Fluorescent Proteins with Experimentally-Characterized In Vivo Maturation Kinetics. PLoS One 2016; 11:e0159292. [PMID: 27479698 PMCID: PMC4968791 DOI: 10.1371/journal.pone.0159292] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 06/30/2016] [Indexed: 11/29/2022] Open
Abstract
Schizosaccharomyces pombe is an outstanding model organism for cell biological investigations, yet the range of useful and well-characterized fluorescent proteins (XFPs) is limited. We generated and characterized three recoded fluorescent proteins for 3-color analysis in S.pombe, Super-folder GFP, monomeric Kusabira Orange 2 and E2Crimson. Upon optimization and expression in S. pombe, the three proteins enabled sensitive simultaneous 3-color detection capability. Furthermore, we describe a strategy that combines a pulse-chase approach and mathematical modeling to quantify the maturation kinetics of these proteins in vivo. We observed maturation kinetics in S. pombe that are expected from those described for these proteins in vitro and/or in other cell types, but also unpredicted behaviors. Our studies provide a kinetically-characterized, integrated three-color XFP toolbox for S. pombe.
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Affiliation(s)
- Bassem Al-Sady
- Department of Microbiology and Immunology, the GW Hooper Foundation, University of California San Francisco, San Francisco, California 94143, United States of America
- * E-mail: (BA-S); (HDM)
| | - Rachel A. Greenstein
- Department of Microbiology and Immunology, the GW Hooper Foundation, University of California San Francisco, San Francisco, California 94143, United States of America
- TETRAD graduate program, University of California San Francisco, San Francisco, California 94143, United States of America
| | - Hana J. El-Samad
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California 94143, United States of America
| | - Sigurd Braun
- Department of Physiological Chemistry, Biomedical Center, Ludwigs-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Hiten D. Madhani
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California 94143, United States of America
- * E-mail: (BA-S); (HDM)
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166
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Le HH, Looney M, Strauss B, Bloodgood M, Jose AM. Tissue homogeneity requires inhibition of unequal gene silencing during development. J Cell Biol 2016; 214:319-31. [PMID: 27458132 PMCID: PMC4970325 DOI: 10.1083/jcb.201601050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 06/29/2016] [Indexed: 11/22/2022] Open
Abstract
Multicellular organisms can generate and maintain homogenous populations of cells that make up individual tissues. However, cellular processes that can disrupt homogeneity and how organisms overcome such disruption are unknown. We found that ∼100-fold differences in expression from a repetitive DNA transgene can occur between intestinal cells in Caenorhabditis elegans These differences are caused by gene silencing in some cells and are actively suppressed by parental and zygotic factors such as the conserved exonuclease ERI-1. If unsuppressed, silencing can spread between some cells in embryos but can be repeat specific and independent of other homologous loci within each cell. Silencing can persist through DNA replication and nuclear divisions, disrupting uniform gene expression in developed animals. Analysis at single-cell resolution suggests that differences between cells arise during early cell divisions upon unequal segregation of an initiator of silencing. Our results suggest that organisms with high repetitive DNA content, which include humans, could use similar developmental mechanisms to achieve and maintain tissue homogeneity.
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Affiliation(s)
- Hai H Le
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742
| | - Monika Looney
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742
| | - Benjamin Strauss
- Center for Advanced Study of Language, University of Maryland, College Park, MD 20742
| | - Michael Bloodgood
- Center for Advanced Study of Language, University of Maryland, College Park, MD 20742
| | - Antony M Jose
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742
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167
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Maison C, Bailly D, Quivy JP, Almouzni G. The methyltransferase Suv39h1 links the SUMO pathway to HP1α marking at pericentric heterochromatin. Nat Commun 2016; 7:12224. [PMID: 27426629 PMCID: PMC4960310 DOI: 10.1038/ncomms12224] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/10/2016] [Indexed: 02/03/2023] Open
Abstract
The trimethylation of histone H3 on lysine 9 (H3K9me3) – a mark recognized by HP1 that depends on the Suv39h lysine methyltransferases (KMTs) – has provided a basis for the reader/writer model to explain HP1 accumulation at pericentric heterochromatin in mammals. Here, we identify the Suv39h1 paralog, as a unique enhancer of HP1α sumoylation both in vitro and in vivo. The region responsible for promoting HP1α sumoylation (aa1–167) is distinct from the KMT catalytic domain and mediates binding to Ubc9. Tethering the 1–167 domain of Suv39h1 to pericentric heterochromatin, but not mutants unable to bind Ubc9, accelerates the de novo targeting of HP1α to these domains. Our results establish an unexpected feature of Suv39h1, distinct from the KMT activity, with a major role for heterochromatin formation. We discuss how linking Suv39h1 to the SUMO pathway provides conceptual implications for our general view on nuclear domain organization and physiological functions. The Suv39h histone methyltransferases promote trimethylation of histone H3 on lysine 9 (H3K9me3). Here, in the Suv39h1 paralog, the authors identify an enhancer of HP1a sumoylation activity that impacts heterochromatin.
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Affiliation(s)
- Christèle Maison
- Institut Curie, PSL Research University, CNRS, UMR3664, Equipe Labellisée Ligue contre le Cancer, F-75005 Paris, France.,Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR3664, F-75005 Paris, France
| | - Delphine Bailly
- Institut Curie, PSL Research University, CNRS, UMR3664, Equipe Labellisée Ligue contre le Cancer, F-75005 Paris, France.,Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR3664, F-75005 Paris, France
| | - Jean-Pierre Quivy
- Institut Curie, PSL Research University, CNRS, UMR3664, Equipe Labellisée Ligue contre le Cancer, F-75005 Paris, France.,Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR3664, F-75005 Paris, France
| | - Geneviève Almouzni
- Institut Curie, PSL Research University, CNRS, UMR3664, Equipe Labellisée Ligue contre le Cancer, F-75005 Paris, France.,Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR3664, F-75005 Paris, France
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168
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Generalized nucleation and looping model for epigenetic memory of histone modifications. Proc Natl Acad Sci U S A 2016; 113:E4180-9. [PMID: 27382173 DOI: 10.1073/pnas.1605862113] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Histone modifications can redistribute along the genome in a sequence-independent manner, giving rise to chromatin position effects and epigenetic memory. The underlying mechanisms shape the endogenous chromatin landscape and determine its response to ectopically targeted histone modifiers. Here, we simulate linear and looping-driven spreading of histone modifications and compare both models to recent experiments on histone methylation in fission yeast. We find that a generalized nucleation-and-looping mechanism describes key observations on engineered and endogenous methylation domains including intrinsic spatial confinement, independent regulation of domain size and memory, variegation in the absence of antagonists, and coexistence of short- and long-term memory at loci with weak and strong constitutive nucleation. These findings support a straightforward relationship between the biochemical properties of chromatin modifiers and the spatiotemporal modification pattern. The proposed mechanism gives rise to a phase diagram for cellular memory that may be generally applicable to explain epigenetic phenomena across different species.
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169
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Abstract
Over the past 20 years, breakthrough discoveries of chromatin-modifying enzymes and associated mechanisms that alter chromatin in response to physiological or pathological signals have transformed our knowledge of epigenetics from a collection of curious biological phenomena to a functionally dissected research field. Here, we provide a personal perspective on the development of epigenetics, from its historical origins to what we define as 'the modern era of epigenetic research'. We primarily highlight key molecular mechanisms of and conceptual advances in epigenetic control that have changed our understanding of normal and perturbed development.
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Affiliation(s)
- C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, 1230 York Avenue, New York 10065, New York, USA
| | - Thomas Jenuwein
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, Freiburg D-79108, Germany
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170
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Martínez-Aguilar K, Ramírez-Carrasco G, Hernández-Chávez JL, Barraza A, Alvarez-Venegas R. Use of BABA and INA As Activators of a Primed State in the Common Bean (Phaseolus vulgaris L.). FRONTIERS IN PLANT SCIENCE 2016; 7:653. [PMID: 27242854 PMCID: PMC4870254 DOI: 10.3389/fpls.2016.00653] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 04/28/2016] [Indexed: 05/10/2023]
Abstract
To survive in adverse conditions, plants have evolved complex mechanisms that "prime" their defense system to respond and adapt to stresses. Their competence to respond to such stresses fundamentally depends on its capacity to modulate the transcriptome rapidly and specifically. Thus, chromatin dynamics is a mechanism linked to transcriptional regulation and enhanced defense in plants. For example, in Arabidopsis, priming of the SA-dependent defense pathway is linked to histone lysine methylation. Such modifications could create a memory of the primary infection that is associated with an amplified gene response upon exposure to a second stress-stimulus. In addition, the priming status of a plant for induced resistance can be inherited to its offspring. However, analyses on the molecular mechanisms of generational and transgenerational priming in the common bean (Phaseolus vulagris L.), an economically important crop, are absent. Here, we provide evidence that resistance to P. syringae pv. phaseolicola infection was induced in the common bean with the synthetic priming activators BABA and INA. Resistance was assessed by evaluating symptom appearance, pathogen accumulation, changes in gene expression of defense genes, as well as changes in the H3K4me3 and H3K36me3 marks at the promoter-exon regions of defense-associated genes. We conclude that defense priming in the common bean occurred in response to BABA and INA and that these synthetic activators primed distinct genes for enhanced disease resistance. We hope that an understanding of the molecular changes leading to defense priming and pathogen resistance will provide valuable knowledge for producing disease-resistant crop varieties by exposing parental plants to priming activators, as well as to the development of novel plant protection chemicals that stimulate the plant's inherent disease resistance mechanisms.
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Affiliation(s)
- Keren Martínez-Aguilar
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad IrapuatoGuanajuato, Mexico
| | | | | | - Aarón Barraza
- Centro de Investigaciones Biológicas del NoroesteLa Paz, Mexico
| | - Raúl Alvarez-Venegas
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad IrapuatoGuanajuato, Mexico
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171
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Nucleation and spreading of a heterochromatic domain in fission yeast. Nat Commun 2016; 7:11518. [PMID: 27167753 PMCID: PMC4865850 DOI: 10.1038/ncomms11518] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 04/05/2016] [Indexed: 12/28/2022] Open
Abstract
Outstanding questions in the chromatin field bear on how large heterochromatin domains are formed in space and time. Positive feedback, where histone-modifying enzymes are attracted to chromosomal regions displaying the modification they catalyse, is believed to drive the formation of these domains; however, few quantitative studies are available to assess this hypothesis. Here we quantified the de novo establishment of a naturally occurring ∼20-kb heterochromatin domain in fission yeast through single-cell analyses, measuring the kinetics of heterochromatin nucleation in a region targeted by RNAi and its subsequent expansion. We found that nucleation of heterochromatin is stochastic and can take from one to ten cell generations. Further silencing of the full region takes another one to ten generations. Quantitative modelling of the observed kinetics emphasizes the importance of local feedback, where a nucleosome-bound enzyme modifies adjacent nucleosomes, combined with a feedback where recruited enzymes can act at a distance. Chromosomes contain large heterochromatin domains. Here, the authors measure the kinetics of heterochromatin formation in fission yeast and show both global and local feedbacks by nucleosome-bound enzymes are important for formation and stability of the large heterochromatin domains.
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172
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Wang J, Jia ST, Jia S. New Insights into the Regulation of Heterochromatin. Trends Genet 2016; 32:284-294. [PMID: 27005444 DOI: 10.1016/j.tig.2016.02.005] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 02/22/2016] [Accepted: 02/29/2016] [Indexed: 10/22/2022]
Abstract
All living organisms are constantly exposed to stresses from internal biological processes and surrounding environments, which induce many adaptive changes in cellular physiology and gene expression programs. Unexpectedly, constitutive heterochromatin, which is generally associated with the stable maintenance of gene silencing, is also dynamically regulated in response to stimuli. In this review we discuss the mechanism of constitutive heterochromatin assembly, its dynamic nature, and its responses to environmental changes.
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Affiliation(s)
- Jiyong Wang
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Sharon T Jia
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, NY, USA.
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173
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Wang J, Cohen AL, Letian A, Tadeo X, Moresco JJ, Liu J, Yates JR, Qiao F, Jia S. The proper connection between shelterin components is required for telomeric heterochromatin assembly. Genes Dev 2016; 30:827-39. [PMID: 26988418 PMCID: PMC4826398 DOI: 10.1101/gad.266718.115] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 02/24/2016] [Indexed: 12/31/2022]
Abstract
Telomeric regions contain prominent sites of heterochromatin, which is associated with unique histone modification profiles such as the methylation of histone H3 at Lys9 (H3K9me). In fission yeast, the conserved telomeric shelterin complex recruits the histone H3K9 methyltransferase complex CLRC to establish subtelomeric heterochromatin. Although many shelterin mutations affect subtelomeric heterochromatin assembly, the mechanism remains elusive due to the diverse functions of shelterin. Through affinity purification, we found that shelterin directly associates with CLRC through the Ccq1 subunit. Surprisingly, mutations that disrupt interactions between shelterin subunits compromise subtelomeric heterochromatin without affecting CLRC interaction with shelterin component Pot1, located at chromosome ends. We further discovered that telomeric repeats are refractory to heterochromatin spreading and that artificial restoration of shelterin connections or increased heterochromatin spreading rescued heterochromatin defects in these shelterin mutants. Thus, subtelomeric heterochromatin assembly requires both the recruitment of CLRC by shelterin to chromosome ends and the proper connection of shelterin components, which allows CLRC to skip telomeric repeats to internal regions.
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Affiliation(s)
- Jiyong Wang
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Allison L Cohen
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Anudari Letian
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Xavier Tadeo
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - James J Moresco
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Jinqiang Liu
- Department of Biological Chemistry, University of California at Irvine, Irvine, California 92697, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Feng Qiao
- Department of Biological Chemistry, University of California at Irvine, Irvine, California 92697, USA
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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174
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Abstract
Single-cell tracking reveals a common “algorithm” of operation used by chromatin regulators
[Also see Report by
Bintu
et al.
]
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Affiliation(s)
- Albert J Keung
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
| | - Ahmad S Khalil
- Department of Biomedical Engineering and Biological Design Center, Boston University, Boston, MA, USA. Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.
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175
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Timms RT, Tchasovnikarova IA, Lehner PJ. Position-effect variegation revisited: HUSHing up heterochromatin in human cells. Bioessays 2016; 38:333-43. [DOI: 10.1002/bies.201500184] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Richard T. Timms
- Department of Medicine, Cambridge Institute for Medical Research; Addenbrooke's Hospital; Cambridge UK
| | - Iva A. Tchasovnikarova
- Department of Medicine, Cambridge Institute for Medical Research; Addenbrooke's Hospital; Cambridge UK
| | - Paul J. Lehner
- Department of Medicine, Cambridge Institute for Medical Research; Addenbrooke's Hospital; Cambridge UK
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176
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Klosin A, Lehner B. Mechanisms, timescales and principles of trans-generational epigenetic inheritance in animals. Curr Opin Genet Dev 2016; 36:41-9. [DOI: 10.1016/j.gde.2016.04.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/31/2016] [Accepted: 04/01/2016] [Indexed: 12/20/2022]
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177
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Bártová E, Večeřa J, Krejčí J, Legartová S, Pacherník J, Kozubek S. The level and distribution pattern of HP1β in the embryonic brain correspond to those of H3K9me1/me2 but not of H3K9me3. Histochem Cell Biol 2016; 145:447-61. [PMID: 26794325 DOI: 10.1007/s00418-015-1402-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2015] [Indexed: 01/13/2023]
Abstract
We studied the histone signature of embryonic and adult brains to strengthen existing evidence of the importance of the histone code in mouse brain development. We analyzed the levels and distribution patterns of H3K9me1, H3K9me2, H3K9me3, and HP1β in both embryonic and adult brains. Western blotting showed that during mouse brain development, the levels of H3K9me1, H3K9me2, and HP1β exhibited almost identical trends, with the highest protein levels occurring at E15 stage. These trends differed from the relatively stable level of H3K9me3 at developmental stages E8, E13, E15, and E18. Compared with embryonic brains, adult brains were characterized by very low levels of H3K9me1/me2/me3 and HP1β. Manipulation of the embryonic epigenome through histone deacetylase inhibitor treatment did not affect the distribution patterns of the studied histone markers in embryonic ventricular ependyma. Similarly, Hdac3 depletion in adult animals had no effect on histone methylation in the adult hippocampus. Our results indicate that the distribution of HP1β in the embryonic mouse brain is related to that of H3K9me1/me2 but not to that of H3K9me3. The unique status of H3K9me3 in the brain was confirmed by its pronounced accumulation in the granular layer of the adult olfactory bulb. Moreover, among the studied proteins, H3K9me3 was the only posttranslational histone modification that was highly abundant at clusters of centromeric heterochromatin, called chromocenters. When we focused on the hippocampus, we found this region to be rich in H3K9me1 and H3K9me3, whereas H3K9me2 and HP1β were present at a very low level or even absent in the hippocampal blade. Taken together, these results revealed differences in the epigenome of the embryonic and adult mouse brain and showed that the adult hippocampus, the granular layer of the adult olfactory bulb, and the ventricular ependyma of the embryonic brain are colonized by specific epigenetic marks.
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Affiliation(s)
- Eva Bártová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic.
| | - Josef Večeřa
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 753/5, Brno, Czech Republic
| | - Jana Krejčí
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Soňa Legartová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Jiří Pacherník
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 753/5, Brno, Czech Republic
| | - Stanislav Kozubek
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
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178
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Barrales RR, Forn M, Georgescu PR, Sarkadi Z, Braun S. Control of heterochromatin localization and silencing by the nuclear membrane protein Lem2. Genes Dev 2016; 30:133-48. [PMID: 26744419 PMCID: PMC4719305 DOI: 10.1101/gad.271288.115] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 12/07/2015] [Indexed: 01/08/2023]
Abstract
Transcriptionally silent chromatin localizes to the nuclear periphery, which provides a special microenvironment for gene repression. A variety of nuclear membrane proteins interact with repressed chromatin, yet the functional role of these interactions remains poorly understood. Here, we show that, in Schizosaccharomyces pombe, the nuclear membrane protein Lem2 associates with chromatin and mediates silencing and heterochromatin localization. Unexpectedly, we found that these functions can be separated and assigned to different structural domains within Lem2, excluding a simple tethering mechanism. Chromatin association and tethering of centromeres to the periphery are mediated by the N-terminal LEM (LAP2-Emerin-MAN1) domain of Lem2, whereas telomere anchoring and heterochromatin silencing require exclusively its conserved C-terminal MSC (MAN1-Src1 C-terminal) domain. Particularly, silencing by Lem2 is epistatic with the Snf2/HDAC (histone deacetylase) repressor complex SHREC at telomeres, while its necessity can be bypassed by deleting Epe1, a JmjC protein with anti-silencing activity. Furthermore, we found that loss of Lem2 reduces heterochromatin association of SHREC, which is accompanied by increased binding of Epe1. This reveals a critical function of Lem2 in coordinating these antagonistic factors at heterochromatin. The distinct silencing and localization functions mediated by Lem2 suggest that these conserved LEM-containing proteins go beyond simple tethering to play active roles in perinuclear silencing.
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Affiliation(s)
- Ramón Ramos Barrales
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Marta Forn
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Paula Raluca Georgescu
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Zsuzsa Sarkadi
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Sigurd Braun
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany; International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
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179
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Espinas NA, Saze H, Saijo Y. Epigenetic Control of Defense Signaling and Priming in Plants. FRONTIERS IN PLANT SCIENCE 2016; 7:1201. [PMID: 27563304 PMCID: PMC4980392 DOI: 10.3389/fpls.2016.01201] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/28/2016] [Indexed: 05/20/2023]
Abstract
Immune recognition of pathogen-associated molecular patterns or effectors leads to defense activation at the pathogen challenged sites. This is followed by systemic defense activation at distant non-challenged sites, termed systemic acquired resistance (SAR). These inducible defenses are accompanied by extensive transcriptional reprogramming of defense-related genes. SAR is associated with priming, in which a subset of these genes is kept at a poised state to facilitate subsequent transcriptional regulation. Transgenerational inheritance of defense-related priming in plants indicates the stability of such primed states. Recent studies have revealed the importance and dynamic engagement of epigenetic mechanisms, such as DNA methylation and histone modifications that are closely linked to chromatin reconfiguration, in plant adaptation to different biotic stresses. Herein we review current knowledge regarding the biological significance and underlying mechanisms of epigenetic control for immune responses in plants. We also argue for the importance of host transposable elements as critical regulators of interactions in the evolutionary "arms race" between plants and pathogens.
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Affiliation(s)
- Nino A. Espinas
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate UniversityOkinawa, Japan
- *Correspondence: Nino A. Espinas, Yusuke Saijo,
| | - Hidetoshi Saze
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate UniversityOkinawa, Japan
| | - Yusuke Saijo
- Nara Institute of Science and TechnologyIkoma, Japan
- Japan Science and Technology Agency, Precursory Research for Embryonic Science and TechnologyKawaguchi, Japan
- *Correspondence: Nino A. Espinas, Yusuke Saijo,
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180
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Epigenome Editing: State of the Art, Concepts, and Perspectives. Trends Genet 2015; 32:101-113. [PMID: 26732754 DOI: 10.1016/j.tig.2015.12.001] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 11/28/2015] [Accepted: 12/01/2015] [Indexed: 12/21/2022]
Abstract
Epigenome editing refers to the directed alteration of chromatin marks at specific genomic loci by using targeted EpiEffectors which comprise designed DNA recognition domains (zinc finger, TAL effector, or modified CRISPR/Cas9 complex) and catalytic domains from a chromatin-modifying enzyme. Epigenome editing is a promising approach for durable gene regulation, with many applications in basic research including the investigation of the regulatory functions and logic of chromatin modifications and cellular reprogramming. From a clinical point of view, targeted regulation of disease-related genes offers novel therapeutic avenues for many diseases. We review here the progress made in this field and discuss open questions in epigenetic regulation and its stability, methods to increase the specificity of epigenome editing, and improved delivery methods for targeted EpiEffectors. Future work will reveal if the approach of epigenome editing fulfills its great promise in basic research and clinical applications.
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181
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Dimitrova E, Turberfield AH, Klose RJ. Histone demethylases in chromatin biology and beyond. EMBO Rep 2015; 16:1620-39. [PMID: 26564907 PMCID: PMC4687429 DOI: 10.15252/embr.201541113] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/06/2015] [Indexed: 01/05/2023] Open
Abstract
Histone methylation plays fundamental roles in regulating chromatin‐based processes. With the discovery of histone demethylases over a decade ago, it is now clear that histone methylation is dynamically regulated to shape the epigenome and regulate important nuclear processes including transcription, cell cycle control and DNA repair. In addition, recent observations suggest that these enzymes could also have functions beyond their originally proposed role as histone demethylases. In this review, we focus on recent advances in our understanding of the molecular mechanisms that underpin the role of histone demethylases in a wide variety of normal cellular processes.
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Affiliation(s)
| | | | - Robert J Klose
- Department of Biochemistry, University of Oxford, Oxford, UK
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182
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Martins NMC, Bergmann JH, Shono N, Kimura H, Larionov V, Masumoto H, Earnshaw WC. Epigenetic engineering shows that a human centromere resists silencing mediated by H3K27me3/K9me3. Mol Biol Cell 2015; 27:177-96. [PMID: 26564795 PMCID: PMC4694756 DOI: 10.1091/mbc.e15-08-0605] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/03/2015] [Indexed: 12/14/2022] Open
Abstract
Centromeres are embedded within heterochromatin but are transcriptionally active. Centromeric transcription and the centromere function of a human artificial chromosome resist repression mediated by nucleation of repressive marks H3K27me3 or H3K9me3 via tethering of EZH2 or the SET domain of Suv39h1, respectively. Centromeres are characterized by the centromere-specific H3 variant CENP-A, which is embedded in chromatin with a pattern characteristic of active transcription that is required for centromere identity. It is unclear how centromeres remain transcriptionally active despite being flanked by repressive pericentric heterochromatin. To further understand centrochromatin’s response to repressive signals, we nucleated a Polycomb-like chromatin state within the centromere of a human artificial chromosome (HAC) by tethering the methyltransferase EZH2. This led to deposition of the H3K27me3 mark and PRC1 repressor binding. Surprisingly, this state did not abolish HAC centromere function or transcription, and this apparent resistance was not observed on a noncentromeric locus, where transcription was silenced. Directly tethering the reader/repressor PRC1 bypassed this resistance, inactivating the centromere. We observed analogous responses when tethering the heterochromatin Editor Suv39h1-methyltransferase domain (centromere resistance) or reader HP1α (centromere inactivation), respectively. Our results reveal that the HAC centromere can resist repressive pathways driven by H3K9me3/H3K27me3 and may help to explain how centromeres are able to resist inactivation by flanking heterochromatin.
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Affiliation(s)
- Nuno M C Martins
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, United Kingdom
| | - Jan H Bergmann
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, United Kingdom
| | - Nobuaki Shono
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, Kisarazu 292-0818, Japan Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Hiroshi Kimura
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Vladimir Larionov
- Laboratory of Molecular Pharmacology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Hiroshi Masumoto
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, Kisarazu 292-0818, Japan
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, United Kingdom
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183
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Sadeghi L, Prasad P, Ekwall K, Cohen A, Svensson JP. The Paf1 complex factors Leo1 and Paf1 promote local histone turnover to modulate chromatin states in fission yeast. EMBO Rep 2015; 16:1673-87. [PMID: 26518661 PMCID: PMC4687421 DOI: 10.15252/embr.201541214] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 10/05/2015] [Indexed: 11/21/2022] Open
Abstract
The maintenance of open and repressed chromatin states is crucial for the regulation of gene expression. To study the genes involved in maintaining chromatin states, we generated a random mutant library in Schizosaccharomyces pombe and monitored the silencing of reporter genes inserted into the euchromatic region adjacent to the heterochromatic mating type locus. We show that Leo1–Paf1 [a subcomplex of the RNA polymerase II‐associated factor 1 complex (Paf1C)] is required to prevent the spreading of heterochromatin into euchromatin by mapping the heterochromatin mark H3K9me2 using high‐resolution genomewide ChIP (ChIP–exo). Loss of Leo1–Paf1 increases heterochromatin stability at several facultative heterochromatin loci in an RNAi‐independent manner. Instead, deletion of Leo1 decreases nucleosome turnover, leading to heterochromatin stabilization. Our data reveal that Leo1–Paf1 promotes chromatin state fluctuations by enhancing histone turnover.
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Affiliation(s)
- Laia Sadeghi
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Punit Prasad
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Karl Ekwall
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Amikam Cohen
- Department of Microbiology and Molecular Genetics, IMRIC The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - J Peter Svensson
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
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184
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Sienski G, Batki J, Senti KA, Dönertas D, Tirian L, Meixner K, Brennecke J. Silencio/CG9754 connects the Piwi-piRNA complex to the cellular heterochromatin machinery. Genes Dev 2015; 29:2258-71. [PMID: 26494711 PMCID: PMC4647559 DOI: 10.1101/gad.271908.115] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 10/05/2015] [Indexed: 11/24/2022]
Abstract
In this study, Sienski et al. characterize CG9754/Silencio as an essential piRNA pathway factor that is required for Piwi's nuclear function in guiding the transcriptional silencing of transposons. These results provide novel insight into the transcriptional silencing process downstream from Piwi and the regulation of piRNA-guided heterochromatin formation. The repression of transposable elements in eukaryotes often involves their transcriptional silencing via targeted chromatin modifications. In animal gonads, nuclear Argonaute proteins of the PIWI clade complexed with small guide RNAs (piRNAs) serve as sequence specificity determinants in this process. How binding of nuclear PIWI–piRNA complexes to nascent transcripts orchestrates heterochromatin formation and transcriptional silencing is unknown. Here, we characterize CG9754/Silencio as an essential piRNA pathway factor that is required for Piwi-mediated transcriptional silencing in Drosophila. Ectopic targeting of Silencio to RNA or DNA is sufficient to elicit silencing independently of Piwi and known piRNA pathway factors. Instead, Silencio requires the H3K9 methyltransferase Eggless/SetDB1 for its silencing ability. In agreement with this, SetDB1, but not Su(var)3-9, is required for Piwi-mediated transcriptional silencing genome-wide. Due to its interaction with the target-engaged Piwi–piRNA complex, we suggest that Silencio acts as linker between the sequence specificity factor Piwi and the cellular heterochromatin machinery.
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Affiliation(s)
- Grzegorz Sienski
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Julia Batki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Kirsten-André Senti
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Derya Dönertas
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Laszlo Tirian
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Katharina Meixner
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Julius Brennecke
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), 1030 Vienna, Austria
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185
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Abstract
Adaptation is the process in which organisms improve their fitness by changing their phenotype using genetic or non-genetic mechanisms. The adaptation toolbox consists of varied molecular and genetic means that we posit span an almost continuous "adaptation spectrum." Different adaptations are characterized by the time needed for organisms to attain them and by their duration. We suggest that organisms often adapt by progressing the adaptation spectrum, starting with rapidly attained physiological and epigenetic adaptations and culminating with slower long-lasting genetic ones. A tantalizing possibility is that earlier adaptations facilitate realization of later ones.
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186
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Asakawa H, Yamamoto TG, Hiraoka Y. Fission yeast meets a legend in Kobe: report of the Eighth International Fission Yeast Meeting. Genes Cells 2015; 20:967-71. [PMID: 26477989 DOI: 10.1111/gtc.12307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 09/14/2015] [Indexed: 11/28/2022]
Abstract
The Eighth International Fission Yeast Meeting, which was held at Ikuta Shrine Hall in Kobe, Japan, from 21 to 26 June 2015, was attended by 327 fission yeast researchers from 25 countries (190 overseas and 137 domestic participants). At this meeting, 124 talks were held and 145 posters were presented. In addition, newly developed database tools were introduced to the community during a workshop. Researchers shared cutting-edge knowledge across broad fields of study, ranging from molecules to evolution, derived from the superior model organism commonly used within the fission yeast community. Intensive discussions and constructive suggestions generated in this meeting will surely advance the understanding of complex biological systems in fission yeast, extending to general eukaryotes.
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Affiliation(s)
- Haruhiko Asakawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
| | - Takaharu G Yamamoto
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.,Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
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187
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Veazey KJ, Parnell SE, Miranda RC, Golding MC. Dose-dependent alcohol-induced alterations in chromatin structure persist beyond the window of exposure and correlate with fetal alcohol syndrome birth defects. Epigenetics Chromatin 2015; 8:39. [PMID: 26421061 PMCID: PMC4587584 DOI: 10.1186/s13072-015-0031-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 09/15/2015] [Indexed: 01/16/2023] Open
Abstract
Background In recent years, we have come to recognize that a multitude of in utero exposures have the capacity to induce the development of congenital and metabolic defects. As most of these encounters manifest their effects beyond the window of exposure, deciphering the mechanisms of teratogenesis is incredibly difficult. For many agents, altered epigenetic programming has become suspect in transmitting the lasting signature of exposure leading to dysgenesis. However, while several chemicals can perturb chromatin structure acutely, for many agents (particularly alcohol) it remains unclear if these modifications represent transient responses to exposure or heritable lesions leading to pathology. Results Here, we report that mice encountering an acute exposure to alcohol on gestational Day-7 exhibit significant alterations in chromatin structure (histone 3 lysine 9 dimethylation, lysine 9 acetylation, and lysine 27 trimethylation) at Day-17, and that these changes strongly correlate with the development of craniofacial and central nervous system defects. Using a neural cortical stem cell model, we find that the epigenetic changes arising as a consequence of alcohol exposure are heavily dependent on the gene under investigation, the dose of alcohol encountered, and that the signatures arising acutely differ significantly from those observed after a 4-day recovery period. Importantly, the changes observed post-recovery are consistent with those modeled in vivo, and associate with alterations in transcripts encoding multiple homeobox genes directing neurogenesis. Unexpectedly, we do not observe a correlation between alcohol-induced changes in chromatin structure and alterations in transcription. Interestingly, the majority of epigenetic changes observed occur in marks associated with repressive chromatin structure, and we identify correlative disruptions in transcripts encoding Dnmt1, Eed, Ehmt2 (G9a), EzH2, Kdm1a, Kdm4c, Setdb1, Sod3, Tet1 and Uhrf1. Conclusions These observations suggest that the immediate and long-term impacts of alcohol exposure on chromatin structure are distinct, and hint at the existence of a possible coordinated
epigenetic response to ethanol during development. Collectively, our results indicate that alcohol-induced modifications to chromatin structure persist beyond the window of exposure, and likely contribute to the development of fetal alcohol syndrome-associated congenital abnormalities. Electronic supplementary material The online version of this article (doi:10.1186/s13072-015-0031-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kylee J Veazey
- Room 338 VMA, 4466 TAMU, Department of Veterinary Physiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466 USA
| | - Scott E Parnell
- Bowles Center for Alcohol Studies and Department of Cell Biology and Physiology, School of Medicine, CB# 7178, University of North Carolina, Chapel Hill, NC 27599 USA
| | - Rajesh C Miranda
- Texas A&M Health Sciences Center, Texas A&M University, 8441 State Highway 47, Clinical Building 1, Suite 3100, Bryan, TX 77807 USA
| | - Michael C Golding
- Room 338 VMA, 4466 TAMU, Department of Veterinary Physiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466 USA
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188
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Cotobal C, Rodríguez-López M, Duncan C, Hasan A, Yamashita A, Yamamoto M, Bähler J, Mata J. Role of Ccr4-Not complex in heterochromatin formation at meiotic genes and subtelomeres in fission yeast. Epigenetics Chromatin 2015; 8:28. [PMID: 26279681 PMCID: PMC4536793 DOI: 10.1186/s13072-015-0018-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 07/22/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Heterochromatin is essential for chromosome segregation, gene silencing and genome integrity. The fission yeast Schizosaccharomyces pombe contains heterochromatin at centromeres, subtelomeres, and mating type genes, as well as at small islands of meiotic genes dispersed across the genome. This heterochromatin is generated by partially redundant mechanisms, including the production of small interfering RNAs (siRNAs) that are incorporated into the RITS protein complex (RNAi-Induced Transcriptional Silencing). The assembly of heterochromatin islands requires the function of the RNA-binding protein Mmi1, which recruits RITS to its mRNA targets and to heterochromatin islands. In addition, Mmi1 directs its targets to an exosome-dependent RNA elimination pathway. RESULTS Ccr4-Not is a conserved multiprotein complex that regulates gene expression at multiple levels, including RNA degradation and translation. We show here that Ccr4-Not is recruited by Mmi1 to its RNA targets. Surprisingly, Ccr4 and Caf1 (the mRNA deadenylase catalytic subunits of the Ccr4-Not complex) are not necessary for the degradation or translation of Mmi1 RNA targets, but are essential for heterochromatin integrity at Mmi1-dependent islands and, independently of Mmi1, at subtelomeric regions. Both roles require the deadenylase activity of Ccr4 and the Mot2/Not4 protein, a ubiquitin ligase that is also part of the complex. Genetic evidence shows that Ccr4-mediated silencing is essential for normal cell growth, indicating that this novel regulation is physiologically relevant. Moreover, Ccr4 interacts with components of the RITS complex in a Mmi1-independent manner. CONCLUSIONS Taken together, our results demonstrate that the Ccr4-Not complex is required for heterochromatin integrity in both Mmi1-dependent and Mmi1-independent pathways.
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Affiliation(s)
- Cristina Cotobal
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - María Rodríguez-López
- Department of Genetics, Evolution and Environment, UCL Cancer Institute, University College London, London, UK
| | - Caia Duncan
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Ayesha Hasan
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Akira Yamashita
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Japan
| | - Masayuki Yamamoto
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Japan
| | - Jürg Bähler
- Department of Genetics, Evolution and Environment, UCL Cancer Institute, University College London, London, UK
| | - Juan Mata
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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189
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Cis-acting determinants of paramutation. Semin Cell Dev Biol 2015; 44:22-32. [DOI: 10.1016/j.semcdb.2015.08.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/20/2015] [Indexed: 11/23/2022]
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190
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Abstract
Genome-wide association studies of complex physiological traits and diseases consistently found that associated genetic factors, such as allelic polymorphisms or DNA mutations, only explained a minority of the expected heritable fraction. This discrepancy is known as “missing heritability”, and its underlying factors and molecular mechanisms are not established. Epigenetic programs may account for a significant fraction of the “missing heritability.” Epigenetic modifications, such as DNA methylation and chromatin assembly states, reflect the high plasticity of the genome and contribute to stably alter gene expression without modifying genomic DNA sequences. Consistent components of complex traits, such as those linked to human stature/height, fertility, and food metabolism or to hereditary defects, have been shown to respond to environmental or nutritional condition and to be epigenetically inherited. The knowledge acquired from epigenetic genome reprogramming during development, stem cell differentiation/de-differentiation, and model organisms is today shedding light on the mechanisms of (a) mitotic inheritance of epigenetic traits from cell to cell, (b) meiotic epigenetic inheritance from generation to generation, and (c) true transgenerational inheritance. Such mechanisms have been shown to include incomplete erasure of DNA methylation, parental effects, transmission of distinct RNA types (mRNA, non-coding RNA, miRNA, siRNA, piRNA), and persistence of subsets of histone marks.
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Affiliation(s)
- Marco Trerotola
- Unit of Cancer Pathology, CeSI, Foundation University 'G. d'Annunzio', Chieti, Italy.
| | - Valeria Relli
- Unit of Cancer Pathology, CeSI, Foundation University 'G. d'Annunzio', Chieti, Italy.
| | - Pasquale Simeone
- Unit of Cancer Pathology, CeSI, Foundation University 'G. d'Annunzio', Chieti, Italy.
| | - Saverio Alberti
- Unit of Cancer Pathology, CeSI, Foundation University 'G. d'Annunzio', Chieti, Italy. .,Department of Neuroscience, Imaging and Clinical Sciences, Unit of Physiology and Physiopathology, 'G. d'Annunzio' University, Chieti, Italy.
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191
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Abstract
Histone variants are an important part of the histone contribution to chromatin epigenetics. In this review, we describe how the known structural differences of these variants from their canonical histone counterparts impart a chromatin signature ultimately responsible for their epigenetic contribution. In terms of the core histones, H2A histone variants are major players while H3 variant CenH3, with a controversial role in the nucleosome conformation, remains the genuine epigenetic histone variant. Linker histone variants (histone H1 family) haven’t often been studied for their role in epigenetics. However, the micro-heterogeneity of the somatic canonical forms of linker histones appears to play an important role in maintaining the cell-differentiated states, while the cell cycle independent linker histone variants are involved in development. A picture starts to emerge in which histone H2A variants, in addition to their individual specific contributions to the nucleosome structure and dynamics, globally impair the accessibility of linker histones to defined chromatin locations and may have important consequences for determining different states of chromatin metabolism.
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Affiliation(s)
- Manjinder S Cheema
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W-3P6, Canada.
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W-3P6, Canada.
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