951
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Long HK, Sims D, Heger A, Blackledge NP, Kutter C, Wright ML, Grützner F, Odom DT, Patient R, Ponting CP, Klose RJ. Epigenetic conservation at gene regulatory elements revealed by non-methylated DNA profiling in seven vertebrates. eLife 2013; 2:e00348. [PMID: 23467541 PMCID: PMC3583005 DOI: 10.7554/elife.00348] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 01/15/2013] [Indexed: 12/19/2022] Open
Abstract
Two-thirds of gene promoters in mammals are associated with regions of non-methylated DNA, called CpG islands (CGIs), which counteract the repressive effects of DNA methylation on chromatin. In cold-blooded vertebrates, computational CGI predictions often reside away from gene promoters, suggesting a major divergence in gene promoter architecture across vertebrates. By experimentally identifying non-methylated DNA in the genomes of seven diverse vertebrates, we instead reveal that non-methylated islands (NMIs) of DNA are a central feature of vertebrate gene promoters. Furthermore, NMIs are present at orthologous genes across vast evolutionary distances, revealing a surprising level of conservation in this epigenetic feature. By profiling NMIs in different tissues and developmental stages we uncover a unifying set of features that are central to the function of NMIs in vertebrates. Together these findings demonstrate an ancient logic for NMI usage at gene promoters and reveal an unprecedented level of epigenetic conservation across vertebrate evolution. DOI:http://dx.doi.org/10.7554/eLife.00348.001.
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Affiliation(s)
- Hannah K Long
- Department of Biochemistry , University of Oxford , Oxford , United Kingdom ; Weatherall Institute of Molecular Medicine, University of Oxford , Oxford , United Kingdom
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952
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Dynamic readers for 5-(hydroxy)methylcytosine and its oxidized derivatives. Cell 2013; 152:1146-59. [PMID: 23434322 DOI: 10.1016/j.cell.2013.02.004] [Citation(s) in RCA: 759] [Impact Index Per Article: 69.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/11/2013] [Accepted: 02/05/2013] [Indexed: 11/21/2022]
Abstract
Tet proteins oxidize 5-methylcytosine (mC) to generate 5-hydroxymethyl (hmC), 5-formyl (fC), and 5-carboxylcytosine (caC). The exact function of these oxidative cytosine bases remains elusive. We applied quantitative mass-spectrometry-based proteomics to identify readers for mC and hmC in mouse embryonic stem cells (mESC), neuronal progenitor cells (NPC), and adult mouse brain tissue. Readers for these modifications are only partially overlapping, and some readers, such as Rfx proteins, display strong specificity. Interactions are dynamic during differentiation, as for example evidenced by the mESC-specific binding of Klf4 to mC and the NPC-specific binding of Uhrf2 to hmC, suggesting specific biological roles for mC and hmC. Oxidized derivatives of mC recruit distinct transcription regulators as well as a large number of DNA repair proteins in mouse ES cells, implicating the DNA damage response as a major player in active DNA demethylation.
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953
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Abstract
DNA methylation is among the best studied epigenetic modifications and is essential to mammalian development. Although the methylation status of most CpG dinucleotides in the genome is stably propagated through mitosis, improvements to methods for measuring methylation have identified numerous regions in which it is dynamically regulated. In this Review, we discuss key concepts in the function of DNA methylation in mammals, stemming from more than two decades of research, including many recent studies that have elucidated when and where DNA methylation has a regulatory role in the genome. We include insights from early development, embryonic stem cells and adult lineages, particularly haematopoiesis, to highlight the general features of this modification as it participates in both global and localized epigenetic regulation.
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954
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Zhong S, Fei Z, Chen YR, Zheng Y, Huang M, Vrebalov J, McQuinn R, Gapper N, Liu B, Xiang J, Shao Y, Giovannoni JJ. Single-base resolution methylomes of tomato fruit development reveal epigenome modifications associated with ripening. Nat Biotechnol 2013; 31:154-9. [PMID: 23354102 DOI: 10.1038/nbt.2462] [Citation(s) in RCA: 469] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 11/22/2012] [Indexed: 01/23/2023]
Abstract
Ripening of tomato fruits is triggered by the plant hormone ethylene, but its effect is restricted by an unknown developmental cue to mature fruits containing viable seeds. To determine whether this cue involves epigenetic remodeling, we expose tomatoes to the methyltransferase inhibitor 5-azacytidine and find that they ripen prematurely. We performed whole-genome bisulfite sequencing on fruit in four stages of development, from immature to ripe. We identified 52,095 differentially methylated regions (representing 1% of the genome) in the 90% of the genome covered by our analysis. Furthermore, binding sites for RIN, one of the main ripening transcription factors, are frequently localized in the demethylated regions of the promoters of numerous ripening genes, and binding occurs in concert with demethylation. Our data show that the epigenome is not static during development and may have been selected to ensure the fidelity of developmental processes such as ripening. Crop-improvement strategies could benefit by taking into account not only DNA sequence variation among plant lines, but also the information encoded in the epigenome.
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Affiliation(s)
- Silin Zhong
- Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York, USA
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955
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Vella P, Scelfo A, Jammula S, Chiacchiera F, Williams K, Cuomo A, Roberto A, Christensen J, Bonaldi T, Helin K, Pasini D. Tet proteins connect the O-linked N-acetylglucosamine transferase Ogt to chromatin in embryonic stem cells. Mol Cell 2013; 49:645-56. [PMID: 23352454 DOI: 10.1016/j.molcel.2012.12.019] [Citation(s) in RCA: 258] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 11/09/2012] [Accepted: 12/20/2012] [Indexed: 01/04/2023]
Abstract
O-linked N-acetylglucosamine (O-GlcNAc) transferase (Ogt) activity is essential for embryonic stem cell (ESC) viability and mouse development. Ogt is present both in the cytoplasm and the nucleus of different cell types and catalyzes serine and threonine glycosylation. We have characterized the biochemical features of nuclear Ogt and identified the ten-eleven translocation (TET) proteins Tet1 and Tet2 as stable partners of Ogt in the nucleus of ESCs. We show at a genome-wide level that Ogt preferentially associates with Tet1 to genes promoters in close proximity of CpG-rich transcription start sites. These regions are characterized by low levels of DNA modification, suggesting a link between Tet1 and Ogt activities in regulating CpG island methylation. Finally, we show that Tet1 is required for binding of Ogt to chromatin affecting Tet1 activity. Taken together, our data characterize how O-GlcNAcylation is recruited to chromatin and interacts with the activity of 5-methylcytosine hydroxylases.
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Affiliation(s)
- Pietro Vella
- Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy
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956
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Ward M, Wilson M, Barbosa-Morais N, Schmidt D, Stark R, Pan Q, Schwalie P, Menon S, Lukk M, Watt S, Thybert D, Kutter C, Kirschner K, Flicek P, Blencowe B, Odom D. Latent regulatory potential of human-specific repetitive elements. Mol Cell 2013; 49:262-72. [PMID: 23246434 PMCID: PMC3560060 DOI: 10.1016/j.molcel.2012.11.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 09/28/2012] [Accepted: 11/09/2012] [Indexed: 12/26/2022]
Abstract
At least half of the human genome is derived from repetitive elements, which are often lineage specific and silenced by a variety of genetic and epigenetic mechanisms. Using a transchromosomic mouse strain that transmits an almost complete single copy of human chromosome 21 via the female germline, we show that a heterologous regulatory environment can transcriptionally activate transposon-derived human regulatory regions. In the mouse nucleus, hundreds of locations on human chromosome 21 newly associate with activating histone modifications in both somatic and germline tissues, and influence the gene expression of nearby transcripts. These regions are enriched with primate and human lineage-specific transposable elements, and their activation corresponds to changes in DNA methylation at CpG dinucleotides. This study reveals the latent regulatory potential of the repetitive human genome and illustrates the species specificity of mechanisms that control it.
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Affiliation(s)
- Michelle C. Ward
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Michael D. Wilson
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Nuno L. Barbosa-Morais
- Banting and Best Department of Medical Research and Department of Molecular Genetics, Donnelly Centre, Toronto, ON M5S 3E1, Canada
| | - Dominic Schmidt
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Rory Stark
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Qun Pan
- Banting and Best Department of Medical Research and Department of Molecular Genetics, Donnelly Centre, Toronto, ON M5S 3E1, Canada
| | - Petra C. Schwalie
- European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton CB10 1SD, UK
| | - Suraj Menon
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Margus Lukk
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Stephen Watt
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - David Thybert
- European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton CB10 1SD, UK
| | - Claudia Kutter
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Kristina Kirschner
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
| | - Paul Flicek
- European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton CB10 1SD, UK
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
| | - Benjamin J. Blencowe
- Banting and Best Department of Medical Research and Department of Molecular Genetics, Donnelly Centre, Toronto, ON M5S 3E1, Canada
| | - Duncan T. Odom
- University of Cambridge, Cancer Research UK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
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957
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Wang H, Maurano MT, Qu H, Varley KE, Gertz J, Pauli F, Lee K, Canfield T, Weaver M, Sandstrom R, Thurman RE, Kaul R, Myers RM, Stamatoyannopoulos JA. Widespread plasticity in CTCF occupancy linked to DNA methylation. Genome Res 2013; 22:1680-8. [PMID: 22955980 PMCID: PMC3431485 DOI: 10.1101/gr.136101.111] [Citation(s) in RCA: 428] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
CTCF is a ubiquitously expressed regulator of fundamental genomic processes including transcription, intra- and interchromosomal interactions, and chromatin structure. Because of its critical role in genome function, CTCF binding patterns have long been assumed to be largely invariant across different cellular environments. Here we analyze genome-wide occupancy patterns of CTCF by ChIP-seq in 19 diverse human cell types, including normal primary cells and immortal lines. We observed highly reproducible yet surprisingly plastic genomic binding landscapes, indicative of strong cell-selective regulation of CTCF occupancy. Comparison with massively parallel bisulfite sequencing data indicates that 41% of variable CTCF binding is linked to differential DNA methylation, concentrated at two critical positions within the CTCF recognition sequence. Unexpectedly, CTCF binding patterns were markedly different in normal versus immortal cells, with the latter showing widespread disruption of CTCF binding associated with increased methylation. Strikingly, this disruption is accompanied by up-regulation of CTCF expression, with the result that both normal and immortal cells maintain the same average number of CTCF occupancy sites genome-wide. These results reveal a tight linkage between DNA methylation and the global occupancy patterns of a major sequence-specific regulatory factor.
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Affiliation(s)
- Hao Wang
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
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958
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High-resolution enzymatic mapping of genomic 5-hydroxymethylcytosine in mouse embryonic stem cells. Cell Rep 2013; 3:567-76. [PMID: 23352666 DOI: 10.1016/j.celrep.2013.01.001] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 11/26/2012] [Accepted: 01/02/2013] [Indexed: 12/20/2022] Open
Abstract
We describe the use of a unique DNA-modification-dependent restriction endonuclease AbaSI coupled with sequencing (Aba-seq) to map high-resolution hydroxymethylome of mouse E14 embryonic stem cells. The specificity of AbaSI enables sensitive detection of 5-hydroxymethylcytosine (5hmC) at low-occupancy regions. Bioinformatic analysis suggests 5hmCs in genic regions closely follow the 5mC distribution. 5hmC is generally depleted in CpG islands and only enriched in a small set of repetitive elements. A regularly spaced and oscillating 5hmC pattern was observed at the binding sites of CTCF. 5hmC is enriched at the poised enhancers with the monomethylated histone H3 lysine 4 (H3K4me1) marks, but not at the active enhancers with the acetylated histone H3 lysine 27 (H3K27Ac) marks. Non-CG hydroxymethylation appears to be prevalent in the mitochondrial genome. We propose that some amounts of transiently stable 5hmCs may indicate a poised epigenetic state or demethylation intermediate, whereas others may suggest a locally accessible chromosomal environment for the TET enzymatic apparatus.
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959
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Extensive changes in DNA methylation are associated with expression of mutant huntingtin. Proc Natl Acad Sci U S A 2013; 110:2354-9. [PMID: 23341638 DOI: 10.1073/pnas.1221292110] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The earliest stages of Huntington disease are marked by changes in gene expression that are caused in an indirect and poorly understood manner by polyglutamine expansions in the huntingtin (HTT) protein. To explore the hypothesis that DNA methylation may be altered in cells expressing mutated HTT, we use reduced representation bisulfite sequencing (RRBS) to map sites of DNA methylation in cells carrying either wild-type or mutant HTT. We find that a large fraction of the genes that change in expression in the presence of mutant huntingtin demonstrate significant changes in DNA methylation. Regions with low CpG content, which have previously been shown to undergo methylation changes in response to neuronal activity, are disproportionately affected. On the basis of the sequence of regions that change in methylation, we identify AP-1 and SOX2 as transcriptional regulators associated with DNA methylation changes, and we confirm these hypotheses using genome-wide chromatin immunoprecipitation sequencing (ChIP-Seq). Our findings suggest new mechanisms for the effects of polyglutamine-expanded HTT. These results also raise important questions about the potential effects of changes in DNA methylation on neurogenesis and cognitive decline in patients with Huntington disease.
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960
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Abstract
DNA methylation is an epigenetic mark that is essential for the development of mammals; it is frequently altered in diseases ranging from cancer to psychiatric disorders. The presence of DNA methylation attracts specialized methyl-DNA binding factors that can then recruit chromatin modifiers. These methyl-CpG binding proteins (MBPs) have key biological roles and can be classified into three structural families: methyl-CpG binding domain (MBD), zinc finger, and SET and RING finger-associated (SRA) domain. The structures of MBD and SRA proteins bound to methylated DNA have been previously determined and shown to exhibit two very different modes of methylated DNA recognition. The last piece of the puzzle has been recently revealed by the structural resolution of two different zinc finger proteins, Kaiso and ZFP57, in complex with methylated DNA. These structures show that the two methyl-CpG binding zinc finger proteins adopt differential methyl-CpG binding modes. Nonetheless, there are similarities with the MBD proteins suggesting some commonalities in methyl-CpG recognition across the various MBP domains. These fresh insights have consequences for the analysis of the many other zinc finger proteins present in the genome, and for the biology of methyl-CpG binding zinc finger proteins.
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961
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Varley KE, Gertz J, Bowling KM, Parker SL, Reddy TE, Pauli-Behn F, Cross MK, Williams BA, Stamatoyannopoulos JA, Crawford GE, Absher DM, Wold BJ, Myers RM. Dynamic DNA methylation across diverse human cell lines and tissues. Genome Res 2013; 23:555-67. [PMID: 23325432 PMCID: PMC3589544 DOI: 10.1101/gr.147942.112] [Citation(s) in RCA: 518] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
As studies of DNA methylation increase in scope, it has become evident that methylation has a complex relationship with gene expression, plays an important role in defining cell types, and is disrupted in many diseases. We describe large-scale single-base resolution DNA methylation profiling on a diverse collection of 82 human cell lines and tissues using reduced representation bisulfite sequencing (RRBS). Analysis integrating RNA-seq and ChIP-seq data illuminates the functional role of this dynamic mark. Loci that are hypermethylated across cancer types are enriched for sites bound by NANOG in embryonic stem cells, which supports and expands the model of a stem/progenitor cell signature in cancer. CpGs that are hypomethylated across cancer types are concentrated in megabase-scale domains that occur near the telomeres and centromeres of chromosomes, are depleted of genes, and are enriched for cancer-specific EZH2 binding and H3K27me3 (repressive chromatin). In noncancer samples, there are cell-type specific methylation signatures preserved in primary cell lines and tissues as well as methylation differences induced by cell culture. The relationship between methylation and expression is context-dependent, and we find that CpG-rich enhancers bound by EP300 in the bodies of expressed genes are unmethylated despite the dense gene-body methylation surrounding them. Non-CpG cytosine methylation occurs in human somatic tissue, is particularly prevalent in brain tissue, and is reproducible across many individuals. This study provides an atlas of DNA methylation across diverse and well-characterized samples and enables new discoveries about DNA methylation and its role in gene regulation and disease.
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962
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Hagarman JA, Motley MP, Kristjansdottir K, Soloway PD. Coordinate regulation of DNA methylation and H3K27me3 in mouse embryonic stem cells. PLoS One 2013; 8:e53880. [PMID: 23326524 PMCID: PMC3543269 DOI: 10.1371/journal.pone.0053880] [Citation(s) in RCA: 76] [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: 05/25/2012] [Accepted: 12/06/2012] [Indexed: 01/29/2023] Open
Abstract
Chromatin is separated into functional domains distinguished by combinatorial patterns of post-translational histone modifications and DNA methylation. Recent studies examining multiple histone modifications have found numerous chromatin states with distinct profiles of chromatin marks and functional enrichments. There are data showing coordinate regulation between DNAme and H3K27me3, which are both involved in the establishment and maintenance of epigenetic gene silencing, but the data are conflicting. Multiple studies have presented evidence to support the theory that PRC2 and DNAme cooperate to achieve silencing, or alternatively that H3K27me3 and DNAme act antagonistically. Here we examine the effect loss of either PRC2 or DNA methyltransferase activity has on the placement of the reciprocal mark in mouse ES cells. We find that DNAme is acting globally to antagonize the placement of H3K27me3, in accordance with recently published results. At least 471,011 domains in the mouse genome acquire H3K27me3 when DNAme is diminished. Of these 466,563 have been shown to be fully methylated in wildtype ES cells, indicating the effects of DNAme on H3K27me3 are direct. In a reciprocal experiment, we examine the effect loss of PRC2 has on the placement of DNAme. In contrast to the global antagonism DNAme has on the placement of H3K27me3, loss of H3K27me3 has a modest effect on DNAme, with only 4% of genes undergoing changes in DNAme, including 861 showing increases and 552 showing losses of overall DNAme. We anticipate that integrating genomic datasets where the effect of loss of a particular epigenetic mark has on the placement of other marks will help elucidate the rules governing epigenetic regulation and what role coordinate regulation of epigenetic marks plays in development and disease.
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Affiliation(s)
- James A. Hagarman
- Division of Nutritional Sciences, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, United States of America
| | - Michael P. Motley
- Division of Nutritional Sciences, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, United States of America
| | - Katla Kristjansdottir
- Division of Nutritional Sciences, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, United States of America
| | - Paul D. Soloway
- Division of Nutritional Sciences, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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963
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DNA methylation changes are a late event in acute promyelocytic leukemia and coincide with loss of transcription factor binding. Blood 2013; 121:178-87. [DOI: 10.1182/blood-2012-08-448860] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Abstract
The origin of aberrant DNA methylation in cancer remains largely unknown. In the present study, we elucidated the DNA methylome in primary acute promyelocytic leukemia (APL) and the role of promyelocytic leukemia–retinoic acid receptor α (PML-RARα) in establishing these patterns. Cells from APL patients showed increased genome-wide DNA methylation with higher variability than healthy CD34+ cells, promyelocytes, and remission BM cells. A core set of differentially methylated regions in APL was identified. Age at diagnosis, Sanz score, and Flt3-mutation status characterized methylation subtypes. Transcription factor–binding sites (eg, the c-myc–binding sites) were associated with low methylation. However, SUZ12- and REST-binding sites identified in embryonic stem cells were preferentially DNA hypermethylated in APL cells. Unexpectedly, PML-RARα–binding sites were also protected from aberrant DNA methylation in APL cells. Consistent with this, myeloid cells from preleukemic PML-RARα knock-in mice did not show altered DNA methylation and the expression of PML-RARα in hematopoietic progenitor cells prevented differentiation without affecting DNA methylation. Treatment of APL blasts with all-trans retinoic acid also did not result in immediate DNA methylation changes. The results of the present study suggest that aberrant DNA methylation is associated with leukemia phenotype but is not required for PML-RARα–mediated initiation of leukemogenesis.
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964
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Zhang S, Zhao S, Wang Z, Li C. Investigation of parent-of-origin SNPs in 5 imprinted genes for forensic purpose. FORENSIC SCIENCE INTERNATIONAL GENETICS SUPPLEMENT SERIES 2013. [DOI: 10.1016/j.fsigss.2013.10.155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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965
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Schäfer A. Gadd45 proteins: key players of repair-mediated DNA demethylation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 793:35-50. [PMID: 24104472 DOI: 10.1007/978-1-4614-8289-5_3] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The three growth arrest and DNA damage 45 (Gadd45) family genes encode for stress-response proteins that are rapidly induced upon cellular stress or differentiation cues. They are well-characterized regulators of cell cycle, senescence, survival, and apoptosis. More recently, it has become clear that Gadd45 proteins promote active DNA demethylation thereby mediating gene activation. This epigenetic function of Gadd45 is important for differentiation and transcriptional regulation during development. Mechanistically, Gadd45 acts as an adapter for DNA repair factors at gene-specific loci to promote removal of 5-methylcytosine from DNA. Hence, Gadd45 is a nexus between DNA repair and epigenetic gene regulation.
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966
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de la Rica L, Rodríguez-Ubreva J, García M, Islam ABMMK, Urquiza JM, Hernando H, Christensen J, Helin K, Gómez-Vaquero C, Ballestar E. PU.1 target genes undergo Tet2-coupled demethylation and DNMT3b-mediated methylation in monocyte-to-osteoclast differentiation. Genome Biol 2013; 14:R99. [PMID: 24028770 PMCID: PMC4054781 DOI: 10.1186/gb-2013-14-9-r99] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 09/09/2013] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND DNA methylation is a key epigenetic mechanism for driving and stabilizing cell-fate decisions. Local deposition and removal of DNA methylation are tightly coupled with transcription factor binding, although the relationship varies with the specific differentiation process. Conversion of monocytes to osteoclasts is a unique terminal differentiation process within the hematopoietic system. This differentiation model is relevant to autoimmune disease and cancer, and there is abundant knowledge on the sets of transcription factors involved. RESULTS Here we focused on DNA methylation changes during osteoclastogenesis. Hypermethylation and hypomethylation changes took place in several thousand genes, including all relevant osteoclast differentiation and function categories. Hypomethylation occurred in association with changes in 5-hydroxymethylcytosine, a proposed intermediate toward demethylation. Transcription factor binding motif analysis revealed an over-representation of PU.1, NF-κB, and AP-1 (Jun/Fos) binding motifs in genes undergoing DNA methylation changes. Among these, only PU.1 motifs were significantly enriched in both hypermethylated and hypomethylated genes; ChIP-seq data analysis confirmed its association to both gene sets. Moreover, PU.1 interacts with both DNMT3b and TET2, suggesting its participation in driving hypermethylation and hydroxymethylation-mediated hypomethylation. Consistent with this, siRNA-mediated PU.1 knockdown in primary monocytes impaired the acquisition of DNA methylation and expression changes, and reduced the association of TET2 and DNMT3b at PU.1 targets during osteoclast differentiation. CONCLUSIONS The work described here identifies key changes in DNA methylation during monocyte-to-osteoclast differentiation and reveals novel roles for PU.1 in this process.
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Affiliation(s)
- Lorenzo de la Rica
- Chromatin and Disease Group, Cancer Epigenetics and Biology Programme (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Javier Rodríguez-Ubreva
- Chromatin and Disease Group, Cancer Epigenetics and Biology Programme (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Mireia García
- Rheumatology Service, Bellvitge University Hospital (HUB), L’Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Abul BMMK Islam
- Department of Experimental and Health Sciences, Barcelona Biomedical Research Park, Universitat Pompeu Fabra (UPF), Barcelona 08003, Spain
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka 1000, Bangladesh
| | - José M Urquiza
- Chromatin and Disease Group, Cancer Epigenetics and Biology Programme (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Henar Hernando
- Chromatin and Disease Group, Cancer Epigenetics and Biology Programme (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Jesper Christensen
- Biotech Research and Innovation Center (BRIC), Center for Epigenetics University of Copenhagen, Ole Maaløes Vej 5, Copenhagen 2200, Denmark
| | - Kristian Helin
- Biotech Research and Innovation Center (BRIC), Center for Epigenetics University of Copenhagen, Ole Maaløes Vej 5, Copenhagen 2200, Denmark
| | - Carmen Gómez-Vaquero
- Rheumatology Service, Bellvitge University Hospital (HUB), L’Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Esteban Ballestar
- Chromatin and Disease Group, Cancer Epigenetics and Biology Programme (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona 08908, Spain
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967
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Guibert S, Weber M. Functions of DNA Methylation and Hydroxymethylation in Mammalian Development. Curr Top Dev Biol 2013; 104:47-83. [DOI: 10.1016/b978-0-12-416027-9.00002-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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968
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Grayson DR, Guidotti A. The dynamics of DNA methylation in schizophrenia and related psychiatric disorders. Neuropsychopharmacology 2013; 38:138-66. [PMID: 22948975 PMCID: PMC3521968 DOI: 10.1038/npp.2012.125] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 02/06/2023]
Abstract
Major psychiatric disorders such as schizophrenia (SZ) and bipolar disorder (BP) with psychosis (BP+) express a complex symptomatology characterized by positive symptoms, negative symptoms, and cognitive impairment. Postmortem studies of human SZ and BP+ brains show considerable alterations in the transcriptome of a variety of cortical structures, including multiple mRNAs that are downregulated in both inhibitory GABAergic and excitatory pyramidal neurons compared with non-psychiatric subjects (NPS). Several reports show increased expression of DNA methyltransferases in telencephalic GABAergic neurons. Accumulating evidence suggests a critical role for altered DNA methylation processes in the pathogenesis of SZ and related psychiatric disorders. The establishment and maintenance of CpG site methylation is essential during central nervous system differentiation and this methylation has been implicated in synaptic plasticity, learning, and memory. Atypical hypermethylation of candidate gene promoters expressed in GABAergic neurons is associated with transcriptional downregulation of the corresponding mRNAs, including glutamic acid decarboxylase 67 (GAD67) and reelin (RELN). Recent reports indicate that the methylation status of promoter proximal CpG dinucleotides is in a dynamic balance between DNA methylation and DNA hydroxymethylation. Hydroxymethylation and subsequent DNA demethylation is more complex and involves additional proteins downstream of 5-hydroxymethylcytosine, including members of the base excision repair (BER) pathway. Recent advances in our understanding of altered CpG methylation, hydroxymethylation, and active DNA demethylation provide a framework for the identification of new targets, which may be exploited for the pharmacological intervention of the psychosis associated with SZ and possibly BP+.
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Affiliation(s)
- Dennis R Grayson
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
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969
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Abstract
The early mammalian embryo is marked by genome-wide parental epigenetic asymmetries, which are directly inherited from the sperm and the oocyte, but are also amplified a few hours after fertilization. The yin-yang of these complementary parental programs is essential for proper development, as uniparental embryos are not viable. The majority of these parental asymmetries are erased, as the embryonic genome assumes its own chromatin signature toward pluripotency and then differentiation, reducing the risk for haploinsufficiency. At a few loci, however, parent-of-origin information persists through development, via maintenance and protective complexes. In this review, we discuss the parental asymmetries that are inherited from the gametes, the forces involved in their elimination, reinforcement or protection, and how this influences the embryonic program. We highlight the gradual loss of all parental asymmetries occurring throughout development, except at imprinted loci, which maintain distinct parent-of-origin chromatin and transcriptional characteristics for life. A deeper understanding of the nongenetic contributions of each germline is important to provide insight into the origin of non-Mendelian inheritance of phenotypic traits, as well as the risk of incompatibilities between parental genomes.
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Affiliation(s)
- Rachel Duffié
- Unité Génétique Biologie du Développement, Institut Curie, UMR3215/INSERM U394, Paris, France
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970
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Abstract
DNA methylation patterns are increasingly surveyed through methods that utilize massively parallel sequencing. Sequence-based assays developed to detect DNA methylation can be broadly divided into those that depend on affinity enrichment, chemical conversion, or enzymatic restriction. The DNA fragments resulting from these methods are uniformly subjected to library construction and massively parallel sequencing. The sequence reads are subsequently aligned to a reference genome and subjected to specialized analytical tools to extract the underlying methylation signature. This chapter will outline these emerging techniques.
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Affiliation(s)
- Martin Hirst
- Department of Microbiology and Immunology, Centre for High-Throughput Biology, University of British Columbia, Vancouver, Canada.
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971
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Acute hypersensitivity of pluripotent testicular cancer-derived embryonal carcinoma to low-dose 5-aza deoxycytidine is associated with global DNA Damage-associated p53 activation, anti-pluripotency and DNA demethylation. PLoS One 2012; 7:e53003. [PMID: 23300844 PMCID: PMC3531428 DOI: 10.1371/journal.pone.0053003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Accepted: 11/26/2012] [Indexed: 12/28/2022] Open
Abstract
Human embryonal carcinoma (EC) cells are the stem cells of nonseminoma testicular germ cells tumors (TGCTs) and share remarkable similarities to human embryonic stem (ES) cells. In prior work we found that EC cells are hypersensitive to low nanomolar doses of 5-aza deoxycytidine (5-aza) and that this hypersensitivity partially depended on unusually high levels of the DNA methyltransferase, DNMT3B. We show here that low-dose 5-aza treatment results in DNA damage and induction of p53 in NT2/D1 cells. In addition, low-dose 5-aza results in global and gene specific promoter DNA hypomethylation. Low-dose 5-aza induces a p53 transcriptional signature distinct from that induced with cisplatin in NT2/D1 cells and also uniquely downregulates genes associated with pluripotency including NANOG, SOX2, GDF3 and Myc target genes. Changes in the p53 and pluripotency signatures with 5-aza were to a large extent dependent on high levels of DNMT3B. In contrast to the majority of p53 target genes upregulated by 5-aza that did not show DNA hypomethylation, several other genes induced with 5-aza had corresponding decreases in promoter methylation. These genes include RIN1, SOX15, GPER, and TLR4 and are novel candidate tumors suppressors in TGCTs. Our studies suggest that the hypersensitivity of NT2/D1 cells to low-dose 5-aza is multifactorial and involves the combined activation of p53 targets, repression of pluripotency genes, and activation of genes repressed by DNA methylation. Low-dose 5-aza therapy may be a general strategy to treat those tumors that are sustained by cells with embryonic stem-like properties.GEO NUMBER FOR THE MICROARRAY DATA: GSE42647.
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972
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Abstract
Deregulation of gene expression, a hallmark of cancer, is caused by both genetic and epigenetic mechanisms. The rapid accumulation of epigenome maps of various cancers suggests a new avenue of research, namely integrating epigenomic data with other types of omic data for cancer diagnosis, prognosis, and biomarker discovery. We introduce the MAPIT algorithm (Multi Analyte Pathway Inference Tool), to enable principled integration of epigenomic, transcriptomic, and protein interactome data. As a proof-of-principle, we apply MAPIT to glioblastoma multiforme (GBM), the most common and aggressive form of brain tumor. Few predictive markers were reported for the prognosis of GBM patients. By integrating mRNA transcriptome, promoter DNA methylome and protein-protein physical interactome, we find ten expression- and three methylation-based network markers, involving 118 genes. When tested on additional GBM patient samples, the prognostic accuracy of the multi-analyte network markers (73.5%) is 9.7% and 8.6% higher than previous prognostic signatures built on gene expression or DNA methylation alone. Our results highlight the critical role of two novel pathways in the prognosis of GBM patients, small GTPase-mediated protein trafficking and ubiquitination-dependent protein degradation. A better understanding of these two pathways could lead to personalized therapies for subgroups of GBM patients. Our study demonstrates that integrating epigenomic, transcriptomic, and interactomic data can improve the accuracy network-based prognosis markers and lead to novel mechanistic understanding of cancer.
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Affiliation(s)
- Jongkwang Kim
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Long Gao
- Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
| | - Kai Tan
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
- Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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973
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Jiang Y, Liu S, Chen X, Cao Y, Tao Y. Genome-wide distribution of DNA methylation and DNA demethylation and related chromatin regulators in cancer. Biochim Biophys Acta Rev Cancer 2012; 1835:155-63. [PMID: 23262191 DOI: 10.1016/j.bbcan.2012.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/08/2012] [Accepted: 12/06/2012] [Indexed: 12/14/2022]
Abstract
DNA methylation plays an important role in the regulation of gene expression, as it is the first epigenetic modification to take place on a given DNA strand. Several factors may directly or indirectly regulate the dynamic distribution of DNA methylation and demethylation between intergenic and intragenic gene regions, thereby controlling gene expression. CpG islands have direct implications for the understanding of DNA methylation patterns in normal conditions and in some common disease states, including cancer. Here, we summarize several recent studies on the genome-wide distribution of DNA methylation and demethylation and their related factors, and we discuss the potential of DNA methylation and demethylation patterns to contribute to gene transcription patterns in tumorigenesis.
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Affiliation(s)
- Yiqun Jiang
- Cancer Research Institute, Central South University, Changsha, Hunan, China
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974
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Yamazaki J, Estecio MR, Lu Y, Long H, Malouf GG, Graber D, Huo Y, Ramagli L, Liang S, Kornblau SM, Jelinek J, Issa JPJ. The epigenome of AML stem and progenitor cells. Epigenetics 2012; 8:92-104. [PMID: 23249680 DOI: 10.4161/epi.23243] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Acute myeloid leukemia (AML) is sustained by a population of cancer stem cells (CSCs or cancer-initiating cell). The mechanisms underlying switches from CSCs to non-CSCs in vivo remain to be understood. We address this issue in AML from the aspect of epigenetics using genome-wide screening for DNA methylation and selected histone modifications. We found no major differences in DNA methylation, especially in promoter CpG islands, between CSCs and non-CSCs. By contrast, we found thousands of genes that change H3K4me3 and/or H3K27me3 status between stem and progenitor cells as well as between progenitor and mature cells. Stem cell related pathways and proliferation or metabolism related pathways characterize genes differentially enriched for H3K4me3/H3K27me3 in stem and progenitor populations. Bivalent genes in stem cells are more plastic during differentiation and are more likely to lose H3K4me3 than to lose H3K27me3, consistent with increasingly closed chromatin state with differentiation. Our data indicates that histone modifications but not promoter DNA methylation are involved in switches from CSCs to non-CSCs in AML.
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Affiliation(s)
- Jumpei Yamazaki
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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975
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Histone demethylase Jumonji D3 (JMJD3) as a tumor suppressor by regulating p53 protein nuclear stabilization. PLoS One 2012; 7:e51407. [PMID: 23236496 PMCID: PMC3517524 DOI: 10.1371/journal.pone.0051407] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2012] [Accepted: 11/01/2012] [Indexed: 01/20/2023] Open
Abstract
Histone methylation regulates normal stem cell fate decisions through a coordinated interplay between histone methyltransferases and demethylases at lineage specific genes. Malignant transformation is associated with aberrant accumulation of repressive histone modifications, such as polycomb mediated histone 3 lysine 27 (H3K27me3) resulting in a histone methylation mediated block to differentiation. The relevance, however, of histone demethylases in cancer remains less clear. We report that JMJD3, a H3K27me3 demethylase, is induced during differentiation of glioblastoma stem cells (GSCs), where it promotes a differentiation-like phenotype via chromatin dependent (INK4A/ARF locus activation) and chromatin independent (nuclear p53 protein stabilization) mechanisms. Our findings indicate that deregulation of JMJD3 may contribute to gliomagenesis via inhibition of the p53 pathway resulting in a block to terminal differentiation.
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976
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Seisenberger S, Andrews S, Krueger F, Arand J, Walter J, Santos F, Popp C, Thienpont B, Dean W, Reik W. The dynamics of genome-wide DNA methylation reprogramming in mouse primordial germ cells. Mol Cell 2012; 48:849-62. [PMID: 23219530 PMCID: PMC3533687 DOI: 10.1016/j.molcel.2012.11.001] [Citation(s) in RCA: 694] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/04/2012] [Accepted: 11/01/2012] [Indexed: 11/29/2022]
Abstract
Genome-wide DNA methylation reprogramming occurs in mouse primordial germ cells (PGCs) and preimplantation embryos, but the precise dynamics and biological outcomes are largely unknown. We have carried out whole-genome bisulfite sequencing (BS-Seq) and RNA-Seq across key stages from E6.5 epiblast to E16.5 PGCs. Global loss of methylation takes place during PGC expansion and migration with evidence for passive demethylation, but sequences that carry long-term epigenetic memory (imprints, CpG islands on the X chromosome, germline-specific genes) only become demethylated upon entry of PGCs into the gonads. The transcriptional profile of PGCs is tightly controlled despite global hypomethylation, with transient expression of the pluripotency network, suggesting that reprogramming and pluripotency are inextricably linked. Our results provide a framework for the understanding of the epigenetic ground state of pluripotency in the germline.
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977
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Affiliation(s)
- Dirk Schübeler
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
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978
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Pachkov M, Balwierz PJ, Arnold P, Ozonov E, van Nimwegen E. SwissRegulon, a database of genome-wide annotations of regulatory sites: recent updates. Nucleic Acids Res 2012. [PMID: 23180783 PMCID: PMC3531101 DOI: 10.1093/nar/gks1145] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Identification of genomic regulatory elements is essential for understanding the dynamics of cellular processes. This task has been substantially facilitated by the availability of genome sequences for many species and high-throughput data of transcripts and transcription factor (TF) binding. However, rigorous computational methods are necessary to derive accurate genome-wide annotations of regulatory sites from such data. SwissRegulon (http://swissregulon.unibas.ch) is a database containing genome-wide annotations of regulatory motifs, promoters and TF binding sites (TFBSs) in promoter regions across model organisms. Its binding site predictions were obtained with rigorous Bayesian probabilistic methods that operate on orthologous regions from related genomes, and use explicit evolutionary models to assess the evidence of purifying selection on each site. New in the current version of SwissRegulon is a curated collection of 190 mammalian regulatory motifs associated with ∼340 TFs, and TFBS annotations across a curated set of ∼35 000 promoters in both human and mouse. Predictions of TFBSs for Saccharomyces cerevisiae have also been significantly extended and now cover 158 of yeast’s ∼180 TFs. All data are accessible through both an easily navigable genome browser with search functions, and as flat files that can be downloaded for further analysis.
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Affiliation(s)
- Mikhail Pachkov
- Biozentrum, University of Basel, and Swiss Institute of Bioinformatics, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
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979
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980
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Quenneville S, Turelli P, Bojkowska K, Raclot C, Offner S, Kapopoulou A, Trono D. The KRAB-ZFP/KAP1 system contributes to the early embryonic establishment of site-specific DNA methylation patterns maintained during development. Cell Rep 2012; 2:766-73. [PMID: 23041315 DOI: 10.1016/j.celrep.2012.08.043] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/18/2012] [Accepted: 08/14/2012] [Indexed: 01/02/2023] Open
Abstract
De novo DNA methylation is an essential aspect of the epigenetic reprogramming that takes place during early development, yet factors responsible for its instatement at particular genomic loci are poorly defined. Here, we demonstrate that the KRAB-ZFP-mediated recruitment of KAP1 to DNA in embryonic stem cells (ESCs) induces cytosine methylation. This process is preceded by H3K9 trimethylation, and genome-wide analyses reveal that it spreads over short distances from KAP1-binding sites so as to involve nearby CpG islands. In sharp contrast, in differentiated cells, KRAB/KAP1-induced heterochromatin formation does not lead to DNA methylation. Correspondingly, the methylation status of CpG islands in the adult mouse liver correlates with their proximity to KAP1-binding sites in ESCs, not in hepatocytes. Therefore, KRAB-ZFPs and their cofactor KAP1 are in part responsible for the establishment during early embryogenesis of site-specific DNA methylation patterns that are maintained through development.
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Affiliation(s)
- Simon Quenneville
- School of Life Sciences and Frontiers in Genetics Program, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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981
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Halachev K, Bast H, Albrecht F, Lengauer T, Bock C. EpiExplorer: live exploration and global analysis of large epigenomic datasets. Genome Biol 2012; 13:R96. [PMID: 23034089 PMCID: PMC3491424 DOI: 10.1186/gb-2012-13-10-r96] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 08/17/2012] [Accepted: 10/03/2012] [Indexed: 12/20/2022] Open
Abstract
Epigenome mapping consortia are generating resources of tremendous value for studying epigenetic regulation. To maximize their utility and impact, new tools are needed that facilitate interactive analysis of epigenome datasets. Here we describe EpiExplorer, a web tool for exploring genome and epigenome data on a genomic scale. We demonstrate EpiExplorer's utility by describing a hypothesis-generating analysis of DNA hydroxymethylation in relation to public reference maps of the human epigenome. All EpiExplorer analyses are performed dynamically within seconds, using an efficient and versatile text indexing scheme that we introduce to bioinformatics. EpiExplorer is available at http://epiexplorer.mpi-inf.mpg.de.
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Affiliation(s)
- Konstantin Halachev
- Max Planck Institute for Informatics, Campus E1.4, 66123 Saarbrücken, Germany
| | - Hannah Bast
- Department of Computer Science, University of Freiburg, Georges-Köhler-Allee 51, 79110 Freiburg, Germany
| | - Felipe Albrecht
- Max Planck Institute for Informatics, Campus E1.4, 66123 Saarbrücken, Germany
| | - Thomas Lengauer
- Max Planck Institute for Informatics, Campus E1.4, 66123 Saarbrücken, Germany
| | - Christoph Bock
- Max Planck Institute for Informatics, Campus E1.4, 66123 Saarbrücken, Germany
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090 Vienna, Austria
- Department of Laboratory Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
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982
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Akalin A, Kormaksson M, Li S, Garrett-Bakelman FE, Figueroa ME, Melnick A, Mason CE. methylKit: a comprehensive R package for the analysis of genome-wide DNA methylation profiles. Genome Biol 2012; 13:R87. [PMID: 23034086 PMCID: PMC3491415 DOI: 10.1186/gb-2012-13-10-r87] [Citation(s) in RCA: 1206] [Impact Index Per Article: 100.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 10/03/2012] [Indexed: 12/14/2022] Open
Abstract
DNA methylation is a chemical modification of cytosine bases that is pivotal for gene regulation,
cellular specification and cancer development. Here, we describe an R package, methylKit, that
rapidly analyzes genome-wide cytosine epigenetic profiles from high-throughput methylation and
hydroxymethylation sequencing experiments. methylKit includes functions for clustering, sample
quality visualization, differential methylation analysis and annotation features, thus automating
and simplifying many of the steps for discerning statistically significant bases or regions of DNA
methylation. Finally, we demonstrate methylKit on breast cancer data, in which we find statistically
significant regions of differential methylation and stratify tumor subtypes. methylKit is available
at http://code.google.com/p/methylkit.
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983
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Skinner MK, Mohan M, Haque MM, Zhang B, Savenkova MI. Epigenetic transgenerational inheritance of somatic transcriptomes and epigenetic control regions. Genome Biol 2012; 13:R91. [PMID: 23034163 PMCID: PMC3491419 DOI: 10.1186/gb-2012-13-10-r91] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 08/23/2012] [Accepted: 10/03/2012] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Environmentally induced epigenetic transgenerational inheritance of adult onset disease involves a variety of phenotypic changes, suggesting a general alteration in genome activity. RESULTS Investigation of different tissue transcriptomes in male and female F3 generation vinclozolin versus control lineage rats demonstrated all tissues examined had transgenerational transcriptomes. The microarrays from 11 different tissues were compared with a gene bionetwork analysis. Although each tissue transgenerational transcriptome was unique, common cellular pathways and processes were identified between the tissues. A cluster analysis identified gene modules with coordinated gene expression and each had unique gene networks regulating tissue-specific gene expression and function. A large number of statistically significant over-represented clusters of genes were identified in the genome for both males and females. These gene clusters ranged from 2-5 megabases in size, and a number of them corresponded to the epimutations previously identified in sperm that transmit the epigenetic transgenerational inheritance of disease phenotypes. CONCLUSIONS Combined observations demonstrate that all tissues derived from the epigenetically altered germ line develop transgenerational transcriptomes unique to the tissue, but common epigenetic control regions in the genome may coordinately regulate these tissue-specific transcriptomes. This systems biology approach provides insight into the molecular mechanisms involved in the epigenetic transgenerational inheritance of a variety of adult onset disease phenotypes.
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Affiliation(s)
- Michael K Skinner
- Center for Reproductive Biology, School of Biological Sciences, Washington State University,
Pullman, WA 99164-4236, USA
| | - Manikkam Mohan
- Center for Reproductive Biology, School of Biological Sciences, Washington State University,
Pullman, WA 99164-4236, USA
| | - Md M Haque
- Center for Reproductive Biology, School of Biological Sciences, Washington State University,
Pullman, WA 99164-4236, USA
| | - Bin Zhang
- Department of Genetics and Genomic Sciences, Institute of Genomics and Multiscale Biology, Mount
Sinai School of Medicine, New York, NY 10029, USA
| | - Marina I Savenkova
- Center for Reproductive Biology, School of Biological Sciences, Washington State University,
Pullman, WA 99164-4236, USA
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984
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Abstract
Epigenetics is a major field of biomedical research, and epigenetic drug discovery shows great promise for new drugs. The first epigenetic inhibitors are already approved for human treatment. Here, we review a number of case studies that cover different aspects of epigenetic drug discovery spanning from sequencing of epigenetic modifications, assays development over screening to medicinal chemistry, in vivo testing and clinical application.
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985
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Directing reprogramming to pluripotency by transcription factors. Curr Opin Genet Dev 2012; 22:416-22. [DOI: 10.1016/j.gde.2012.07.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 07/02/2012] [Indexed: 11/24/2022]
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986
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Arnold P, Schöler A, Pachkov M, Balwierz PJ, Jørgensen H, Stadler MB, van Nimwegen E, Schübeler D. Modeling of epigenome dynamics identifies transcription factors that mediate Polycomb targeting. Genome Res 2012; 23:60-73. [PMID: 22964890 PMCID: PMC3530684 DOI: 10.1101/gr.142661.112] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although changes in chromatin are integral to transcriptional reprogramming during cellular differentiation, it is currently unclear how chromatin modifications are targeted to specific loci. To systematically identify transcription factors (TFs) that can direct chromatin changes during cell fate decisions, we model the relationship between genome-wide dynamics of chromatin marks and the local occurrence of computationally predicted TF binding sites. By applying this computational approach to a time course of Polycomb-mediated H3K27me3 marks during neuronal differentiation of murine stem cells, we identify several motifs that likely regulate the dynamics of this chromatin mark. Among these, the sites bound by REST and by the SNAIL family of TFs are predicted to transiently recruit H3K27me3 in neuronal progenitors. We validate these predictions experimentally and show that absence of REST indeed causes loss of H3K27me3 at target promoters in trans, specifically at the neuronal progenitor state. Moreover, using targeted transgenic insertion, we show that promoter fragments containing REST or SNAIL binding sites are sufficient to recruit H3K27me3 in cis, while deletion of these sites results in loss of H3K27me3. These findings illustrate that the occurrence of TF binding sites can determine chromatin dynamics. Local determination of Polycomb activity by REST and SNAIL motifs exemplifies such TF based regulation of chromatin. Furthermore, our results show that key TFs can be identified ab initio through computational modeling of epigenome data sets using a modeling approach that we make readily accessible.
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Affiliation(s)
- Phil Arnold
- Biozentrum of the University of Basel and Swiss Institute of Bioinformatics, CH 4056 Basel, Switzerland
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987
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Thurman RE, Rynes E, Humbert R, Vierstra J, Maurano MT, Haugen E, Sheffield NC, Stergachis AB, Wang H, Vernot B, Garg K, Sandstrom R, Bates D, Canfield TK, Diegel M, Dunn D, Ebersol AK, Frum T, Giste E, Harding L, Johnson AK, Johnson EM, Kutyavin T, Lajoie B, Lee BK, Lee K, London D, Lotakis D, Neph S, Neri F, Nguyen ED, Reynolds AP, Roach V, Safi A, Sanchez ME, Sanyal A, Shafer A, Simon JM, Song L, Vong S, Weaver M, Zhang Z, Zhang Z, Lenhard B, Tewari M, Dorschner MO, Hansen RS, Navas PA, Stamatoyannopoulos G, Iyer VR, Lieb JD, Sunyaev SR, Akey JM, Sabo PJ, Kaul R, Furey TS, Dekker J, Crawford GE, Stamatoyannopoulos JA. The accessible chromatin landscape of the human genome. Nature 2012; 489:75-82. [PMID: 22955617 PMCID: PMC3721348 DOI: 10.1038/nature11232] [Citation(s) in RCA: 1919] [Impact Index Per Article: 159.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 05/15/2012] [Indexed: 02/07/2023]
Abstract
DNase I hypersensitive sites (DHSs) are markers of regulatory DNA and have underpinned the discovery of all classes of cis-regulatory elements including enhancers, promoters, insulators, silencers and locus control regions. Here we present the first extensive map of human DHSs identified through genome-wide profiling in 125 diverse cell and tissue types. We identify ∼2.9 million DHSs that encompass virtually all known experimentally validated cis-regulatory sequences and expose a vast trove of novel elements, most with highly cell-selective regulation. Annotating these elements using ENCODE data reveals novel relationships between chromatin accessibility, transcription, DNA methylation and regulatory factor occupancy patterns. We connect ∼580,000 distal DHSs with their target promoters, revealing systematic pairing of different classes of distal DHSs and specific promoter types. Patterning of chromatin accessibility at many regulatory regions is organized with dozens to hundreds of co-activated elements, and the transcellular DNase I sensitivity pattern at a given region can predict cell-type-specific functional behaviours. The DHS landscape shows signatures of recent functional evolutionary constraint. However, the DHS compartment in pluripotent and immortalized cells exhibits higher mutation rates than that in highly differentiated cells, exposing an unexpected link between chromatin accessibility, proliferative potential and patterns of human variation.
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Affiliation(s)
- Robert E. Thurman
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Eric Rynes
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Richard Humbert
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Jeff Vierstra
- Department of Genome Sciences, University of Washington, Seattle, WA
| | | | - Eric Haugen
- Department of Genome Sciences, University of Washington, Seattle, WA
| | | | | | - Hao Wang
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Benjamin Vernot
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Kavita Garg
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA
| | - Richard Sandstrom
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Daniel Bates
- Department of Genome Sciences, University of Washington, Seattle, WA
| | | | - Morgan Diegel
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Douglas Dunn
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Abigail K. Ebersol
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Tristan Frum
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Erika Giste
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Lisa Harding
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Audra K. Johnson
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Ericka M. Johnson
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Tanya Kutyavin
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Bryan Lajoie
- Program in Gene Function, University of Massachusetts Medical School, Worcester, MA
| | - Bum-Kyu Lee
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX
| | - Kristen Lee
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Darin London
- Institute for Genome Sciences and Policy, Duke University, Durham, NC
| | - Dimitra Lotakis
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Shane Neph
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Fidencio Neri
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Eric D. Nguyen
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Alex P. Reynolds
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Vaughn Roach
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Alexias Safi
- Institute for Genome Sciences and Policy, Duke University, Durham, NC
| | - Minerva E. Sanchez
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Amartya Sanyal
- Program in Gene Function, University of Massachusetts Medical School, Worcester, MA
| | - Anthony Shafer
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Jeremy M. Simon
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Lingyun Song
- Institute for Genome Sciences and Policy, Duke University, Durham, NC
| | - Shinny Vong
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Molly Weaver
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Zhancheng Zhang
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Zhuzhu Zhang
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Boris Lenhard
- Bergen Center for Computational Science, University of Bergen, Bergen, Norway
| | - Muneesh Tewari
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA
| | - Michael O. Dorschner
- Dept. of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA
| | - R. Scott Hansen
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Patrick A. Navas
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | | | - Vishwanath R. Iyer
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX
| | - Jason D. Lieb
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Shamil R. Sunyaev
- Dept. of Medicine, Division of Genetics, Brigham & Women’s Hospital and Harvard Medical School, Boston, MA
| | - Joshua M. Akey
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Peter J. Sabo
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Rajinder Kaul
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA
| | - Terrence S. Furey
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Job Dekker
- Program in Gene Function, University of Massachusetts Medical School, Worcester, MA
| | | | - John A. Stamatoyannopoulos
- Department of Genome Sciences, University of Washington, Seattle, WA
- Department of Medicine, Division of Oncology, University of Washington, Seattle, WA
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988
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Greer JM, McCombe PA. The role of epigenetic mechanisms and processes in autoimmune disorders. Biologics 2012; 6:307-27. [PMID: 23055689 PMCID: PMC3459549 DOI: 10.2147/btt.s24067] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Indexed: 12/18/2022]
Abstract
The lack of complete concordance of autoimmune disease in identical twins suggests that nongenetic factors play a major role in determining disease susceptibility. In this review, we consider how epigenetic mechanisms could affect the immune system and effector mechanisms in autoimmunity and/or the target organ of autoimmunity and thus affect the development of autoimmune diseases. We also consider the types of stimuli that lead to epigenetic modifications and how these relate to the epidemiology of autoimmune diseases and the biological pathways operative in different autoimmune diseases. Increasing our knowledge of these epigenetic mechanisms and processes will increase the prospects for controlling or preventing autoimmune diseases in the future through the use of drugs that target the epigenetic pathways.
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Affiliation(s)
- Judith M Greer
- The University of Queensland, UQ Centre for Clinical Research, Brisbane, Queensland, Australia
| | - Pamela A McCombe
- The University of Queensland, UQ Centre for Clinical Research, Brisbane, Queensland, Australia
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989
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Epigenetic obstacles encountered by transcription factors: reprogramming against all odds. Curr Opin Genet Dev 2012; 22:409-15. [PMID: 22922161 DOI: 10.1016/j.gde.2012.08.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 07/24/2012] [Accepted: 08/02/2012] [Indexed: 12/24/2022]
Abstract
Reprogramming of a somatic nucleus to an induced pluripotent state can be achieved in vitro through ectopic expression of Oct4 (Pou5f1), Sox2, Klf4 and c-Myc. While the ability of these factors to regulate transcription in a pluripotent context has been studied extensively, their ability to interact with and remodel a somatic genome remains underexplored. Several recent studies have begun to provide mechanistic insights that will eventually lead to a more rational design and improved understanding of nuclear reprogramming.
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990
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Kalari S, Jung M, Kernstine KH, Takahashi T, Pfeifer GP. The DNA methylation landscape of small cell lung cancer suggests a differentiation defect of neuroendocrine cells. Oncogene 2012; 32:3559-68. [PMID: 22907430 DOI: 10.1038/onc.2012.362] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 05/18/2012] [Accepted: 07/04/2012] [Indexed: 12/23/2022]
Abstract
Small cell lung cancer (SCLC) is a disease characterized by aggressive clinical behavior and lack of effective therapy. Owing to its tendency for early dissemination, only a third of patients have limited-stage disease at the time of diagnosis. SCLC is thought to derive from pulmonary neuroendocrine cells. Although several molecular abnormalities in SCLC have been described, there are relatively few studies on epigenetic alterations in this type of tumor. Here, we have used methylation profiling with the methylated-CpG island recovery assay in combination with microarrays and conducted the first genome-scale analysis of methylation changes that occur in primary SCLC and SCLC cell lines. Among the hundreds of tumor-specifically methylated genes discovered, we identified 73 gene targets that are methylated in >77% of primary SCLC tumors, most of which have never been linked to aberrant methylation in tumors. These methylated targets have potential for biomarker development for early detection and therapeutic management of SCLC. SCLC cell lines had a greater number of hypermethylated genes than primary tumors. Gene ontology analysis indicated a significant enrichment of methylated genes functioning as transcription factors and in processes of neuronal differentiation. Motif analysis of tumor-specific methylated regions identified enrichment of binding sites for several neural cell fate-specifying transcription factors including NEUROD1, HAND1, ZNF423 and REST. We hypothesize that two potential mechanisms, loss of cell fate-determining transcription factors by methylation of their promoters and functional inactivation of their corresponding genomic-binding sites by DNA methylation, can promote a differentiation defect of neuroendocrine cells thus enhancing the ability of tumor progenitor cells to transition toward SCLC.
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Affiliation(s)
- S Kalari
- Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, CA, USA
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991
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Spitz F, Furlong EEM. Transcription factors: from enhancer binding to developmental control. Nat Rev Genet 2012; 13:613-26. [PMID: 22868264 DOI: 10.1038/nrg3207] [Citation(s) in RCA: 1373] [Impact Index Per Article: 114.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Developmental progression is driven by specific spatiotemporal domains of gene expression, which give rise to stereotypically patterned embryos even in the presence of environmental and genetic variation. Views of how transcription factors regulate gene expression are changing owing to recent genome-wide studies of transcription factor binding and RNA expression. Such studies reveal patterns that, at first glance, seem to contrast with the robustness of the developmental processes they encode. Here, we review our current knowledge of transcription factor function from genomic and genetic studies and discuss how different strategies, including extensive cooperative regulation (both direct and indirect), progressive priming of regulatory elements, and the integration of activities from multiple enhancers, confer specificity and robustness to transcriptional regulation during development.
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Affiliation(s)
- François Spitz
- Developmental Biology Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany.
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992
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Hoffmann A, Spengler D. The lasting legacy of social stress on the epigenome of the hypothalamic–pituitary–adrenal axis. Epigenomics 2012; 4:431-44. [DOI: 10.2217/epi.12.34] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Social stress is a major factor contributing to early-life adversity that has taken on an epidemic scale. Early social stress leads to long-lasting changes in behavior, cognition, mood and neuroendocrine responses predisposing to or sheltering from stress-related diseases later in life. Epigenetic mechanisms are thought to mediate the effects of early social stress on the epigenome, and can give rise to persistent memories hard coded by DNA methylation. The hypothalamic–pituitary–adrenal axis canalizes early social stress, which leaves its footprints at key regulator sites of this highly plastic system. Thereby, social stress-induced DNA memories mirror the complexity of the stress response and sex differences in brain epigenetics. Timely therapeutic interventions should aim to attenuate early social stress-derived DNA markings and their life-long consequences for mental health.
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Affiliation(s)
- Anke Hoffmann
- Max Planck Institute of Psychiatry, Molecular Neuroendocrinology, Kraepelinstrasse 2–10, D-80804 Munich, Germany
| | - Dietmar Spengler
- Max Planck Institute of Psychiatry, Molecular Neuroendocrinology, Kraepelinstrasse 2–10, D-80804 Munich, Germany
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993
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Sievers C, Schlumpf T, Sawarkar R, Comoglio F, Paro R. Mixture models and wavelet transforms reveal high confidence RNA-protein interaction sites in MOV10 PAR-CLIP data. Nucleic Acids Res 2012; 40:e160. [PMID: 22844102 PMCID: PMC3488208 DOI: 10.1093/nar/gks697] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The Photo-Activatable Ribonucleoside-enhanced CrossLinking and ImmunoPrecipitation (PAR-CLIP) method was recently developed for global identification of RNAs interacting with proteins. The strength of this versatile method results from induction of specific T to C transitions at sites of interaction. However, current analytical tools do not distinguish between non-experimentally and experimentally induced transitions. Furthermore, geometric properties at potential binding sites are not taken into account. To surmount these shortcomings, we developed a two-step algorithm consisting of a non-parametric two-component mixture model and a wavelet-based peak calling procedure. Our algorithm can reduce the number of false positives up to 24% thereby identifying high confidence interaction sites. We successfully employed this approach in conjunction with a modified PAR-CLIP protocol to study the functional role of nuclear Moloney leukemia virus 10, a putative RNA helicase interacting with Argonaute2 and Polycomb. Our method, available as the R package wavClusteR, is generally applicable to any substitution-based inference problem in genomics.
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Affiliation(s)
- Cem Sievers
- Department of Biosystems Science and Engineering, Swiss Federal Institute of Technology Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
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994
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Bock C, Beerman I, Lien WH, Smith ZD, Gu H, Boyle P, Gnirke A, Fuchs E, Rossi DJ, Meissner A. DNA methylation dynamics during in vivo differentiation of blood and skin stem cells. Mol Cell 2012; 47:633-47. [PMID: 22841485 DOI: 10.1016/j.molcel.2012.06.019] [Citation(s) in RCA: 278] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 04/09/2012] [Accepted: 06/21/2012] [Indexed: 01/19/2023]
Abstract
DNA methylation is a mechanism of epigenetic regulation that is common to all vertebrates. Functional studies underscore its relevance for tissue homeostasis, but the global dynamics of DNA methylation during in vivo differentiation remain underexplored. Here we report high-resolution DNA methylation maps of adult stem cell differentiation in mouse, focusing on 19 purified cell populations of the blood and skin lineages. DNA methylation changes were locus specific and relatively modest in magnitude. They frequently overlapped with lineage-associated transcription factors and their binding sites, suggesting that DNA methylation may protect cells from aberrant transcription factor activation. DNA methylation and gene expression provided complementary information, and combining the two enabled us to infer the cellular differentiation hierarchy of the blood lineage directly from genome-scale data. In summary, these results demonstrate that in vivo differentiation of adult stem cells is associated with small but informative changes in the genomic distribution of DNA methylation.
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Affiliation(s)
- Christoph Bock
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
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995
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Coskun V, Tsoa R, Sun YE. Epigenetic regulation of stem cells differentiating along the neural lineage. Curr Opin Neurobiol 2012; 22:762-7. [PMID: 22835699 DOI: 10.1016/j.conb.2012.07.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 06/30/2012] [Accepted: 07/04/2012] [Indexed: 01/16/2023]
Abstract
Many lineage-specific genes are poised and silenced in stem cells. Upon differentiation, genes that are related to self-renewal and alternative lineages are stably silenced. CpG methylation at proximal promoters and PRC2-mediated H3K27me3 play a role in silencing genes temporarily or permanently, with or without coexistence of active epigenetic marks, respectively. Interestingly, DNA methylation on neuronal genes that is distal to transcription start site enable transcription activation owing to its ability to repel PRC2-mediated inhibition. In addition, DNA demethylase Tet proteins play a role in regulation of changes in DNA methylation and related H3K27me3 during differentiation. Collectively, a complex epigenetic network formed by H3K4me3, histone acetylation/deacetylation, H3K27me3 and DNA methylation/demethylation act together to regulate stem cell self-renewal and differentiation.
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Affiliation(s)
- Volkan Coskun
- Intellectual and Developmental Disabilities Research Center, Departments of Psychiatry & Behavioral Sciences and Molecular & Medical Pharmacology, Semel Institute for Neuroscience, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095, United States
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996
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Wilson GA, Dhami P, Feber A, Cortázar D, Suzuki Y, Schulz R, Schär P, Beck S. Resources for methylome analysis suitable for gene knockout studies of potential epigenome modifiers. Gigascience 2012; 1:3. [PMID: 23587164 PMCID: PMC3617451 DOI: 10.1186/2047-217x-1-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/12/2012] [Indexed: 01/07/2023] Open
Abstract
Background Methylated DNA immunoprecipitation (MeDIP) is a popular enrichment based method and can be combined with sequencing (termed MeDIP-seq) to interrogate the methylation status of cytosines across entire genomes. However, quality control and analysis of MeDIP-seq data have remained to be a challenge. Results We report genome-wide DNA methylation profiles of wild type (wt) and mutant mouse cells, comprising 3 biological replicates of Thymine DNA glycosylase (Tdg) knockout (KO) embryonic stem cells (ESCs), in vitro differentiated neural precursor cells (NPCs) and embryonic fibroblasts (MEFs). The resulting 18 methylomes were analysed with MeDUSA (Methylated DNA Utility for Sequence Analysis), a novel MeDIP-seq computational analysis pipeline for the identification of differentially methylated regions (DMRs). The observed increase of hypermethylation in MEF promoter-associated CpG islands supports a previously proposed role for Tdg in the protection of regulatory regions from epigenetic silencing. Further analysis of genes and regions associated with the DMRs by gene ontology, pathway, and ChIP analyses revealed further insights into Tdg function, including an association of TDG with low-methylated distal regulatory regions. Conclusions We demonstrate that MeDUSA is able to detect both large-scale changes between cells from different stages of differentiation and also small but significant changes between the methylomes of cells that only differ in the KO of a single gene. These changes were validated utilising publicly available datasets and confirm TDG's function in the protection of regulatory regions from epigenetic silencing.
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Affiliation(s)
- Gareth A Wilson
- Medical Genomics, UCL Cancer Institute, University College London, London, UK.
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997
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Liu Y, Siegmund KD, Laird PW, Berman BP. Bis-SNP: combined DNA methylation and SNP calling for Bisulfite-seq data. Genome Biol 2012; 13:R61. [PMID: 22784381 PMCID: PMC3491382 DOI: 10.1186/gb-2012-13-7-r61] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 07/04/2012] [Indexed: 01/08/2023] Open
Abstract
Bisulfite treatment of DNA followed by high-throughput sequencing (Bisulfite-seq) is an important method for studying DNA methylation and epigenetic gene regulation, yet current software tools do not adequately address single nucleotide polymorphisms (SNPs). Identifying SNPs is important for accurate quantification of methylation levels and for identification of allele-specific epigenetic events such as imprinting. We have developed a model-based bisulfite SNP caller, Bis-SNP, that results in substantially better SNP calls than existing methods, thereby improving methylation estimates. At an average 30× genomic coverage, Bis-SNP correctly identified 96% of SNPs using the default high-stringency settings. The open-source package is available at http://epigenome.usc.edu/publicationdata/bissnp2011.
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998
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Teng L, Tan K. Finding combinatorial histone code by semi-supervised biclustering. BMC Genomics 2012; 13:301. [PMID: 22759587 PMCID: PMC3443427 DOI: 10.1186/1471-2164-13-301] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 06/12/2012] [Indexed: 11/18/2022] Open
Abstract
Background Combinatorial histone modification is an important epigenetic mechanism for regulating chromatin state and gene expression. Given the rapid accumulation of genome-wide histone modification maps, there is a pressing need for computational methods capable of joint analysis of multiple maps to reveal combinatorial modification patterns. Results We present the Semi-Supervised Coherent and Shifted Bicluster Identification algorithm (SS-CoSBI). It uses prior knowledge of combinatorial histone modifications to guide the biclustering process. Specifically, co-occurrence frequencies of histone modifications characterized by mass spectrometry are used as probabilistic priors to adjust the similarity measure in the biclustering process. Using a high-quality set of transcriptional enhancers and associated histone marks, we demonstrate that SS-CoSBI outperforms its predecessor by finding histone modification and genomic locus biclusters with higher enrichment of enhancers. We apply SS-CoSBI to identify multiple cell-type-specific combinatorial histone modification states associated with human enhancers. We show enhancer histone modification states are correlated with the expression of nearby genes. Further, we find that enhancers with the histone mark H3K4me1 have higher levels of DNA methylation and decreased expression of nearby genes, suggesting a functional interplay between H3K4me1 and DNA methylation that can modulate enhancer activities. Conclusions The analysis presented here provides a systematic characterization of combinatorial histone codes of enhancers across three human cell types using a novel semi-supervised biclustering algorithm. As epigenomic maps accumulate, SS-CoSBI will become increasingly useful for understanding combinatorial chromatin modifications by taking advantage of existing knowledge. Availability and implementation SS-CoSBI is implemented in C. The source code is freely available at http://www.healthcare.uiowa.edu/labs/tan/SS-CoSBI.gz.
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Affiliation(s)
- Li Teng
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
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999
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Sérandour AA, Avner S, Oger F, Bizot M, Percevault F, Lucchetti-Miganeh C, Palierne G, Gheeraert C, Barloy-Hubler F, Péron CL, Madigou T, Durand E, Froguel P, Staels B, Lefebvre P, Métivier R, Eeckhoute J, Salbert G. Dynamic hydroxymethylation of deoxyribonucleic acid marks differentiation-associated enhancers. Nucleic Acids Res 2012; 40:8255-65. [PMID: 22730288 PMCID: PMC3458548 DOI: 10.1093/nar/gks595] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Enhancers are developmentally controlled transcriptional regulatory regions whose activities are modulated through histone modifications or histone variant deposition. In this study, we show by genome-wide mapping that the newly discovered deoxyribonucleic acid (DNA) modification 5-hydroxymethylcytosine (5hmC) is dynamically associated with transcription factor binding to distal regulatory sites during neural differentiation of mouse P19 cells and during adipocyte differentiation of mouse 3T3-L1 cells. Functional annotation reveals that regions gaining 5hmC are associated with genes expressed either in neural tissues when P19 cells undergo neural differentiation or in adipose tissue when 3T3-L1 cells undergo adipocyte differentiation. Furthermore, distal regions gaining 5hmC together with H3K4me2 and H3K27ac in P19 cells behave as differentiation-dependent transcriptional enhancers. Identified regions are enriched in motifs for transcription factors regulating specific cell fates such as Meis1 in P19 cells and PPARγ in 3T3-L1 cells. Accordingly, a fraction of hydroxymethylated Meis1 sites were associated with a dynamic engagement of the 5-methylcytosine hydroxylase Tet1. In addition, kinetic studies of cytosine hydroxymethylation of selected enhancers indicated that DNA hydroxymethylation is an early event of enhancer activation. Hence, acquisition of 5hmC in cell-specific distal regulatory regions may represent a major event of enhancer progression toward an active state and participate in selective activation of tissue-specific genes.
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Affiliation(s)
- Aurélien A Sérandour
- Université de Rennes 1, CNRS UMR6290, Team SP@RTE, Campus de Beaulieu, Rennes F-35042, France
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1000
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Tilman G, Arnoult N, Lenglez S, Van Beneden A, Loriot A, De Smet C, Decottignies A. Cancer-linked satellite 2 DNA hypomethylation does not regulate Sat2 non-coding RNA expression and is initiated by heat shock pathway activation. Epigenetics 2012; 7:903-13. [PMID: 22722874 DOI: 10.4161/epi.21107] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Epigenetic dysfunctions, including DNA methylation alterations, play major roles in cancer initiation and progression. Although it is well established that gene promoter demethylation activates transcription, it remains unclear whether hypomethylation of repetitive heterochromatin similarly affects expression of non-coding RNA from these loci. Understanding how repetitive non-coding RNAs are transcriptionally regulated is important given that their established upregulation by the heat shock (HS) pathway suggests important functions in cellular response to stress, possibly by promoting heterochromatin reconstruction. We found that, although pericentromeric satellite 2 (Sat2) DNA hypomethylation is detected in a majority of cancer cell lines of various origins, DNA methylation loss does not constitutively hyperactivate Sat2 expression, and also does not facilitate Sat2 transcriptional induction upon heat shock. In melanoma tumor samples, our analysis revealed that the HS response, frequently upregulated in tumors, is probably the main determinant of Sat2 RNA expression in vivo. Next, we tested whether HS pathway hyperactivation may drive Sat2 demethylation. Strikingly, we found that both hyperthermia and hyperactivated RasV12 oncogene, another potent inducer of the HS pathway, reduced Sat2 methylation levels by up to 27% in human fibroblasts recovering from stress. Demethylation occurred locally on Sat2 repeats, resulting in a demethylation signature that was also detected in cancer cell lines with moderate genome-wide hypomethylation. We therefore propose that upregulation of Sat2 transcription in response to HS pathway hyperactivation during tumorigenesis may promote localized demethylation of the locus. This, in turn, may contribute to tumorigenesis, as demethylation of Sat2 was previously reported to favor chromosomal rearrangements.
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Affiliation(s)
- Gaëlle Tilman
- Genetic and Epigenetic Alterations of Genomes Research Group, de Duve Institute, Catholic University of Louvain, Brussels, Belgium
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