101
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Aranda S, Mas G, Di Croce L. Regulation of gene transcription by Polycomb proteins. SCIENCE ADVANCES 2015; 1:e1500737. [PMID: 26665172 PMCID: PMC4672759 DOI: 10.1126/sciadv.1500737] [Citation(s) in RCA: 236] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Accepted: 09/17/2015] [Indexed: 05/14/2023]
Abstract
The Polycomb group (PcG) of proteins defines a subset of factors that physically associate and function to maintain the positional identity of cells from the embryo to adult stages. PcG has long been considered a paradigmatic model for epigenetic maintenance of gene transcription programs. Despite intensive research efforts to unveil the molecular mechanisms of action of PcG proteins, several fundamental questions remain unresolved: How many different PcG complexes exist in mammalian cells? How are PcG complexes targeted to specific loci? How does PcG regulate transcription? In this review, we discuss the diversity of PcG complexes in mammalian cells, examine newly identified modes of recruitment to chromatin, and highlight the latest insights into the molecular mechanisms underlying the function of PcGs in transcription regulation and three-dimensional chromatin conformation.
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Affiliation(s)
- Sergi Aranda
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
- Universitat Pompeu Fabra (UPF), Barcelona 08002, Spain
| | - Gloria Mas
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
- Universitat Pompeu Fabra (UPF), Barcelona 08002, Spain
| | - Luciano Di Croce
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
- Universitat Pompeu Fabra (UPF), Barcelona 08002, Spain
- Institucio Catalana de Recerca i Estudis Avançats, Pg Lluis Companys 23, Barcelona 08010, Spain
- Corresponding author. E-mail:
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102
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The quest for mammalian Polycomb response elements: are we there yet? Chromosoma 2015; 125:471-96. [PMID: 26453572 PMCID: PMC4901126 DOI: 10.1007/s00412-015-0539-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 08/31/2015] [Accepted: 09/02/2015] [Indexed: 12/12/2022]
Abstract
A long-standing mystery in the field of Polycomb and Trithorax regulation is how these proteins, which are highly conserved between flies and mammals, can regulate several hundred equally highly conserved target genes, but recognise these targets via cis-regulatory elements that appear to show no conservation in their DNA sequence. These elements, termed Polycomb/Trithorax response elements (PRE/TREs or PREs), are relatively well characterised in flies, but their mammalian counterparts have proved to be extremely difficult to identify. Recent progress in this endeavour has generated a wealth of data and raised several intriguing questions. Here, we ask why and to what extent mammalian PREs are so different to those of the fly. We review recent advances, evaluate current models and identify open questions in the quest for mammalian PREs.
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103
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Alabert C, Barth TK, Reverón-Gómez N, Sidoli S, Schmidt A, Jensen ON, Imhof A, Groth A. Two distinct modes for propagation of histone PTMs across the cell cycle. Genes Dev 2015; 29:585-90. [PMID: 25792596 PMCID: PMC4378191 DOI: 10.1101/gad.256354.114] [Citation(s) in RCA: 263] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Epigenetic states defined by chromatin can be maintained through mitotic cell division. However, it remains unknown how histone-based information is transmitted. Here we combine nascent chromatin capture (NCC) and triple-SILAC (stable isotope labeling with amino acids in cell culture) labeling to track histone modifications and histone variants during DNA replication and across the cell cycle. We show that post-translational modifications (PTMs) are transmitted with parental histones to newly replicated DNA. Di- and trimethylation marks are diluted twofold upon DNA replication, as a consequence of new histone deposition. Importantly, within one cell cycle, all PTMs are restored. In general, new histones are modified to mirror the parental histones. However, H3K9 trimethylation (H3K9me3) and H3K27me3 are propagated by continuous modification of parental and new histones because the establishment of these marks extends over several cell generations. Together, our results reveal how histone marks propagate and demonstrate that chromatin states oscillate within the cell cycle.
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Affiliation(s)
- Constance Alabert
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Teresa K Barth
- Munich Centre of Integrated Protein Science, Ludwig-Maximillians University of Munich, 80336 Munich, Germany; Adolf Butenandt Institute, Ludwig-Maximillians University of Munich, 80336 Munich, Germany
| | - Nazaret Reverón-Gómez
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Simone Sidoli
- Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark; Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Andreas Schmidt
- Munich Centre of Integrated Protein Science, Ludwig-Maximillians University of Munich, 80336 Munich, Germany; Adolf Butenandt Institute, Ludwig-Maximillians University of Munich, 80336 Munich, Germany
| | - Ole N Jensen
- Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark; Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Axel Imhof
- Munich Centre of Integrated Protein Science, Ludwig-Maximillians University of Munich, 80336 Munich, Germany; Adolf Butenandt Institute, Ludwig-Maximillians University of Munich, 80336 Munich, Germany;
| | - Anja Groth
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark; Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark;
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104
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Veazey KJ, Parnell SE, Miranda RC, Golding MC. Dose-dependent alcohol-induced alterations in chromatin structure persist beyond the window of exposure and correlate with fetal alcohol syndrome birth defects. Epigenetics Chromatin 2015; 8:39. [PMID: 26421061 PMCID: PMC4587584 DOI: 10.1186/s13072-015-0031-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 09/15/2015] [Indexed: 01/16/2023] Open
Abstract
Background In recent years, we have come to recognize that a multitude of in utero exposures have the capacity to induce the development of congenital and metabolic defects. As most of these encounters manifest their effects beyond the window of exposure, deciphering the mechanisms of teratogenesis is incredibly difficult. For many agents, altered epigenetic programming has become suspect in transmitting the lasting signature of exposure leading to dysgenesis. However, while several chemicals can perturb chromatin structure acutely, for many agents (particularly alcohol) it remains unclear if these modifications represent transient responses to exposure or heritable lesions leading to pathology. Results Here, we report that mice encountering an acute exposure to alcohol on gestational Day-7 exhibit significant alterations in chromatin structure (histone 3 lysine 9 dimethylation, lysine 9 acetylation, and lysine 27 trimethylation) at Day-17, and that these changes strongly correlate with the development of craniofacial and central nervous system defects. Using a neural cortical stem cell model, we find that the epigenetic changes arising as a consequence of alcohol exposure are heavily dependent on the gene under investigation, the dose of alcohol encountered, and that the signatures arising acutely differ significantly from those observed after a 4-day recovery period. Importantly, the changes observed post-recovery are consistent with those modeled in vivo, and associate with alterations in transcripts encoding multiple homeobox genes directing neurogenesis. Unexpectedly, we do not observe a correlation between alcohol-induced changes in chromatin structure and alterations in transcription. Interestingly, the majority of epigenetic changes observed occur in marks associated with repressive chromatin structure, and we identify correlative disruptions in transcripts encoding Dnmt1, Eed, Ehmt2 (G9a), EzH2, Kdm1a, Kdm4c, Setdb1, Sod3, Tet1 and Uhrf1. Conclusions These observations suggest that the immediate and long-term impacts of alcohol exposure on chromatin structure are distinct, and hint at the existence of a possible coordinated
epigenetic response to ethanol during development. Collectively, our results indicate that alcohol-induced modifications to chromatin structure persist beyond the window of exposure, and likely contribute to the development of fetal alcohol syndrome-associated congenital abnormalities. Electronic supplementary material The online version of this article (doi:10.1186/s13072-015-0031-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kylee J Veazey
- Room 338 VMA, 4466 TAMU, Department of Veterinary Physiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466 USA
| | - Scott E Parnell
- Bowles Center for Alcohol Studies and Department of Cell Biology and Physiology, School of Medicine, CB# 7178, University of North Carolina, Chapel Hill, NC 27599 USA
| | - Rajesh C Miranda
- Texas A&M Health Sciences Center, Texas A&M University, 8441 State Highway 47, Clinical Building 1, Suite 3100, Bryan, TX 77807 USA
| | - Michael C Golding
- Room 338 VMA, 4466 TAMU, Department of Veterinary Physiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466 USA
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105
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Zhang J, Dominguez-Sola D, Hussein S, Lee JE, Holmes AB, Bansal M, Vlasevska S, Mo T, Tang H, Basso K, Ge K, Dalla-Favera R, Pasqualucci L. Disruption of KMT2D perturbs germinal center B cell development and promotes lymphomagenesis. Nat Med 2015; 21:1190-8. [PMID: 26366712 PMCID: PMC5145002 DOI: 10.1038/nm.3940] [Citation(s) in RCA: 301] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 08/11/2015] [Indexed: 12/12/2022]
Abstract
Mutations in the gene encoding the KMT2D (or MLL2) methyltransferase are highly recurrent and occur early during tumorigenesis in diffuse large B cell lymphoma (DLBCL) and follicular lymphoma (FL). However, the functional consequences of these mutations and their role in lymphomagenesis are unknown. Here we show that FL- and DLBCL-associated KMT2D mutations impair KMT2D enzymatic activity, leading to diminished global H3K4 methylation in germinal-center (GC) B cells and DLBCL cells. Conditional deletion of Kmt2d early during B cell development, but not after initiation of the GC reaction, results in an increase in GC B cells and enhances B cell proliferation in mice. Moreover, genetic ablation of Kmt2d in mice overexpressing Bcl2 increases the incidence of GC-derived lymphomas resembling human tumors. These findings suggest that KMT2D acts as a tumor suppressor gene whose early loss facilitates lymphomagenesis by remodeling the epigenetic landscape of the cancer precursor cells. Eradication of KMT2D-deficient cells may thus represent a rational therapeutic approach for targeting early tumorigenic events.
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Affiliation(s)
- Jiyuan Zhang
- Institute for Cancer Genetics, Columbia University, New York, New York, USA
| | - David Dominguez-Sola
- Institute for Cancer Genetics, Columbia University, New York, New York, USA.,Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Shafinaz Hussein
- Institute for Cancer Genetics, Columbia University, New York, New York, USA
| | - Ji-Eun Lee
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Antony B Holmes
- Institute for Cancer Genetics, Columbia University, New York, New York, USA
| | - Mukesh Bansal
- Department of Systems Biology, Columbia University, New York, New York, USA
| | - Sofija Vlasevska
- Institute for Cancer Genetics, Columbia University, New York, New York, USA
| | - Tongwei Mo
- Institute for Cancer Genetics, Columbia University, New York, New York, USA
| | - Hongyan Tang
- Institute for Cancer Genetics, Columbia University, New York, New York, USA
| | - Katia Basso
- Institute for Cancer Genetics, Columbia University, New York, New York, USA.,Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Kai Ge
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Riccardo Dalla-Favera
- Institute for Cancer Genetics, Columbia University, New York, New York, USA.,Department of Pathology and Cell Biology, Columbia University, New York, New York, USA.,Department of Genetics &Development, Columbia University, New York, New York, USA.,Department of Microbiology &Immunology, Columbia University, New York, New York, USA.,Herbert Irving Comprehensive Cancer Center, Columbia University, New York, New York, USA
| | - Laura Pasqualucci
- Institute for Cancer Genetics, Columbia University, New York, New York, USA.,Department of Pathology and Cell Biology, Columbia University, New York, New York, USA.,Herbert Irving Comprehensive Cancer Center, Columbia University, New York, New York, USA
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106
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Abstract
Eukaryotic replication disrupts each nucleosome as the fork passes, followed by re-assembly of disrupted nucleosomes and incorporation of newly synthesized histones into nucleosomes in the daughter genomes. In this review, we examine this process of replication-coupled nucleosome assembly to understand how characteristic steady state nucleosome landscapes are attained. Recent studies have begun to elucidate mechanisms involved in histone transfer during replication and maturation of the nucleosome landscape after disruption by replication. A fuller understanding of replication-coupled nucleosome assembly will be needed to explain how epigenetic information is replicated at every cell division.
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Affiliation(s)
- Srinivas Ramachandran
- Howard Hughes Medical Institute, Seattle, WA 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Seattle, WA 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
- Corresponding author. E-mail:
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107
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Abstract
Histone variants are an important part of the histone contribution to chromatin epigenetics. In this review, we describe how the known structural differences of these variants from their canonical histone counterparts impart a chromatin signature ultimately responsible for their epigenetic contribution. In terms of the core histones, H2A histone variants are major players while H3 variant CenH3, with a controversial role in the nucleosome conformation, remains the genuine epigenetic histone variant. Linker histone variants (histone H1 family) haven’t often been studied for their role in epigenetics. However, the micro-heterogeneity of the somatic canonical forms of linker histones appears to play an important role in maintaining the cell-differentiated states, while the cell cycle independent linker histone variants are involved in development. A picture starts to emerge in which histone H2A variants, in addition to their individual specific contributions to the nucleosome structure and dynamics, globally impair the accessibility of linker histones to defined chromatin locations and may have important consequences for determining different states of chromatin metabolism.
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Affiliation(s)
- Manjinder S Cheema
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W-3P6, Canada.
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W-3P6, Canada.
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108
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Berry S, Dean C. Environmental perception and epigenetic memory: mechanistic insight through FLC. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:133-48. [PMID: 25929799 PMCID: PMC4691321 DOI: 10.1111/tpj.12869] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 04/13/2015] [Accepted: 04/20/2015] [Indexed: 05/18/2023]
Abstract
Chromatin plays a central role in orchestrating gene regulation at the transcriptional level. However, our understanding of how chromatin states are altered in response to environmental and developmental cues, and then maintained epigenetically over many cell divisions, remains poor. The floral repressor gene FLOWERING LOCUS C (FLC) in Arabidopsis thaliana is a useful system to address these questions. FLC is transcriptionally repressed during exposure to cold temperatures, allowing studies of how environmental conditions alter expression states at the chromatin level. FLC repression is also epigenetically maintained during subsequent development in warm conditions, so that exposure to cold may be remembered. This memory depends on molecular complexes that are highly conserved among eukaryotes, making FLC not only interesting as a paradigm for understanding biological decision-making in plants, but also an important system for elucidating chromatin-based gene regulation more generally. In this review, we summarize our understanding of how cold temperature induces a switch in the FLC chromatin state, and how this state is epigenetically remembered. We also discuss how the epigenetic state of FLC is reprogrammed in the seed to ensure a requirement for cold exposure in the next generation.
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Affiliation(s)
- Scott Berry
- John Innes Centre, Norwich Research ParkNorwich, NR4 7UH, UK
| | - Caroline Dean
- John Innes Centre, Norwich Research ParkNorwich, NR4 7UH, UK
- * For correspondence (e-mail )
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109
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Abstract
A close relationship between proliferation and cell fate specification has been well documented in many developmental systems. In addition to the gradual cell fate changes accompanying normal development and tissue homeostasis, it is now commonly appreciated that cell fate could also undergo drastic changes, as illustrated by the induction of pluripotency from many differentiated somatic cell types during the process of Yamanaka reprogramming. Strikingly, the drastic cell fate change induced by Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc) is preceded by extensive cell cycle acceleration. Prompted by our recent discovery that progression toward pluripotency from rare somatic cells could bypass the stochastic phase of reprogramming and that a key feature of these somatic cells is an ultrafast cell cycle (~8 h/cycle), we assess whether cell cycle dynamics could provide a general framework for controlling cell fate. Several potential mechanisms on how cell cycle dynamics may impact cell fate determination by regulating chromatin, key transcription factor concentration, or their interactions are discussed. Specific challenges and implications for studying and manipulating cell fate are considered.
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110
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Annunziato AT. The Fork in the Road: Histone Partitioning During DNA Replication. Genes (Basel) 2015; 6:353-71. [PMID: 26110314 PMCID: PMC4488668 DOI: 10.3390/genes6020353] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/15/2015] [Accepted: 06/16/2015] [Indexed: 12/22/2022] Open
Abstract
In the following discussion the distribution of histones at the replication fork is examined, with specific attention paid to the question of H3/H4 tetramer "splitting." After a presentation of early experiments surrounding this topic, more recent contributions are detailed. The implications of these findings with respect to the transmission of histone modifications and epigenetic models are also addressed.
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Affiliation(s)
- Anthony T Annunziato
- Biology Department, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA.
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111
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Abyzov A, Li S, Kim DR, Mohiyuddin M, Stütz AM, Parrish NF, Mu XJ, Clark W, Chen K, Hurles M, Korbel JO, Lam HYK, Lee C, Gerstein MB. Analysis of deletion breakpoints from 1,092 humans reveals details of mutation mechanisms. Nat Commun 2015; 6:7256. [PMID: 26028266 PMCID: PMC4451611 DOI: 10.1038/ncomms8256] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 04/21/2015] [Indexed: 02/07/2023] Open
Abstract
Investigating genomic structural variants at basepair resolution is crucial for understanding their formation mechanisms. We identify and analyze 8,943 deletion breakpoints in 1,092 samples from the 1000 Genomes Project. We find breakpoints have more nearby SNPs and indels than the genomic average, likely a consequence of relaxed selection. By investigating the correlation of breakpoints with DNA methylation, Hi-C interactions, and histone marks and the substitution patterns of nucleotides near them, we find that breakpoints with the signature of non-allelic homologous recombination (NAHR) are associated with open chromatin. We hypothesize that some NAHR deletions occur without DNA replication and cell division, in embryonic and germline cells. In contrast, breakpoints associated with non-homologous (NH) mechanisms often have sequence micro-insertions, templated from later replicating genomic sites, spaced at two characteristic distances from the breakpoint. These micro-insertions are consistent with template-switching events and suggest a particular spatiotemporal configuration for DNA during the events.
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Affiliation(s)
- Alexej Abyzov
- Department of Health Sciences Research, Center for Individualized Medicine, Mayo Clinic, 200 1st Street SW, Rochester, Minnesota 55905, USA
| | - Shantao Li
- 1] Program in Computational Biology and Bioinformatics, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06520, USA [2] Department of Computer Science, Yale University, New Haven, Connecticut 06520, USA
| | - Daniel Rhee Kim
- Department of Computer Science, Yale University, New Haven, Connecticut 06520, USA
| | | | - Adrian M Stütz
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg 69117, Germany
| | | | - Xinmeng Jasmine Mu
- 1] Program in Computational Biology and Bioinformatics, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06520, USA [2] Department of Molecular Biophysics and Biochemistry, School of Medicine, Yale University, New Haven, Connecticut 06520, USA
| | - Wyatt Clark
- 1] Program in Computational Biology and Bioinformatics, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06520, USA [2] Department of Molecular Biophysics and Biochemistry, School of Medicine, Yale University, New Haven, Connecticut 06520, USA
| | - Ken Chen
- The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Matthew Hurles
- Department of Human Genetics, Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK
| | - Jan O Korbel
- 1] European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg 69117, Germany [2] European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SD, UK
| | - Hugo Y K Lam
- Bina Technologies, Roche Sequencing, Redwood City, California 94065, USA
| | - Charles Lee
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut 06030, USA
| | - Mark B Gerstein
- 1] Program in Computational Biology and Bioinformatics, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06520, USA [2] Department of Molecular Biophysics and Biochemistry, School of Medicine, Yale University, New Haven, Connecticut 06520, USA [3] Department of Computer Science, Yale University, New Haven, Connecticut 06520, USA
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112
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Abstract
Histone-lysine N-methyltransferase 2 (KMT2) family proteins methylate lysine 4 on the histone H3 tail at important regulatory regions in the genome and thereby impart crucial functions through modulating chromatin structures and DNA accessibility. Although the human KMT2 family was initially named the mixed-lineage leukaemia (MLL) family, owing to the role of the first-found member KMT2A in this disease, recent exome-sequencing studies revealed KMT2 genes to be among the most frequently mutated genes in many types of human cancers. Efforts to integrate the molecular mechanisms of KMT2 with its roles in tumorigenesis have led to the development of first-generation inhibitors of KMT2 function, which could become novel cancer therapies.
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Affiliation(s)
- Rajesh C. Rao
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48109
| | - Yali Dou
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109
- Correspondence: , Tel: (734) 6151315, Fax: (734) 7636476
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113
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Kamikawa YF, Donohoe ME. Histone demethylation maintains Prdm14 and Tsix expression and represses xIst in embryonic stem cells. PLoS One 2015; 10:e0125626. [PMID: 25993097 PMCID: PMC4439117 DOI: 10.1371/journal.pone.0125626] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/24/2015] [Indexed: 12/31/2022] Open
Abstract
Epigenetic reprogramming is exemplified by the remarkable changes observed in cellular differentiation and X-chromosome inactivation (XCI) in mammalian female cells. Histone 3 lysine 27 trimethylation (H3K27me3) is a modification that suppresses gene expression in multiple contexts including embryonic stem cells (ESCs) and decorates the entire inactive X-chromosome. The conversion of female somatic cells to induced pluripotency is accompanied by X-chromosome reactivation (XCR) and H3K27me3 erasure. Here, we show that the H3K27-specific demethylase Utx regulates the expression of the master regulators for XCI and XCR: Prdm14, Tsix, and Xist. Female ESC transcriptome analysis using a small molecule inhibitor for H3K27 demethylases, GSK-J4, identifies novel targets of H3K27 demethylation. Consistent with a recent report that GSK-J4 can inhibit other histone demethylase, we found that elevated H3K4me3 levels are associated with increased gene expression including Xist. Our data suggest multiple regulatory mechanisms for XCI via histone demethylation.
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Affiliation(s)
- Yasunao F. Kamikawa
- Burke Medical Research Institute, White Plains, New York, United States of America
- Department of Neuroscience Brain Mind Research Institute, Weill Cornell Medical College, New York, New York, United States of America
- Department of Cell & Development, Weill Cornell Medical College, New York, New York, United States of America
| | - Mary E. Donohoe
- Burke Medical Research Institute, White Plains, New York, United States of America
- Department of Neuroscience Brain Mind Research Institute, Weill Cornell Medical College, New York, New York, United States of America
- Department of Cell & Development, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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114
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Imamura T, Uesaka M, Nakashima K. Epigenetic setting and reprogramming for neural cell fate determination and differentiation. Philos Trans R Soc Lond B Biol Sci 2015; 369:rstb.2013.0511. [PMID: 25135972 DOI: 10.1098/rstb.2013.0511] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In the mammalian brain, epigenetic mechanisms are clearly involved in the regulation of self-renewal of neural stem cells and the derivation of their descendants, i.e. neurons, astrocytes and oligodendrocytes, according to the developmental timing and the microenvironment, the 'niche'. Interestingly, local epigenetic changes occur, concomitantly with genome-wide level changes, at a set of gene promoter regions for either down- or upregulation of the gene. In addition, intergenic regions also sensitize the availability of epigenetic modifiers, which affects gene expression through a relatively long-range chromatinic interaction with the transcription regulatory machineries including non-coding RNA (ncRNA) such as promoter-associated ncRNA and enhancer ncRNA. We show that such an epigenetic landscape in a neural cell is statically but flexibly formed together with a variable combination of generally and locally acting nuclear molecules including master transcription factors and cell-cycle regulators. We also discuss the possibility that revealing the epigenetic regulation by the local DNA-RNA-protein assemblies would promote methodological innovations, e.g. neural cell reprogramming, engineering and transplantation, to manipulate neuronal and glial cell fates for the purpose of medical use of these cells.
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Affiliation(s)
- Takuya Imamura
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masahiro Uesaka
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan Department of Biophysics, Division of Biological Sciences, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kinichi Nakashima
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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115
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Berry S, Hartley M, Olsson TSG, Dean C, Howard M. Local chromatin environment of a Polycomb target gene instructs its own epigenetic inheritance. eLife 2015; 4:e07205. [PMID: 25955967 PMCID: PMC4450441 DOI: 10.7554/elife.07205] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/07/2015] [Indexed: 01/10/2023] Open
Abstract
Inheritance of gene expression states is fundamental for cells to 'remember' past events, such as environmental or developmental cues. The conserved Polycomb Repressive Complex 2 (PRC2) maintains epigenetic repression of many genes in animals and plants and modifies chromatin at its targets. Histones modified by PRC2 can be inherited through cell division. However, it remains unclear whether this inheritance can direct long-term memory of individual gene expression states (cis memory) or instead if local chromatin states are dictated by the concentrations of diffusible factors (trans memory). By monitoring the expression of two copies of the Arabidopsis Polycomb target gene FLOWERING LOCUS C (FLC) in the same plants, we show that one copy can be repressed while the other is active. Furthermore, this 'mixed' expression state is inherited through many cell divisions as plants develop. These data demonstrate that epigenetic memory of FLC expression is stored not in trans but in cis.
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116
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Ishikawa M, Hasebe M. Cell cycle reentry from the late S phase: implications from stem cell formation in the moss Physcomitrella patens. JOURNAL OF PLANT RESEARCH 2015; 128:399-405. [PMID: 25801272 DOI: 10.1007/s10265-015-0713-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 02/22/2015] [Indexed: 06/04/2023]
Abstract
Differentiated cells are in a non-dividing, quiescent state, but some differentiated cells can reenter the cell cycle in response to appropriate stimuli. Quiescent cells are generally arrested at the G0/G1 phase, reenter the cell cycle, and progress to the S phase to replicate their genomic DNA. On the other hand, some types of cells are arrested at the different phase and reenter the cell cycle from there. In the moss Physcomitrella patens, the differentiated leaf cells of gametophores formed in the haploid generation contain approximately 2C DNA content, and DNA synthesis is necessary for reentry into the cell cycle, which is suggested to be arrested at late S phase. Here we review various cell-division reactivation processes in which cells reenter the cell cycle from the late S phase, and discuss possible mechanisms of such unusual cell cycle reentries with special emphasis on Physcomitrella.
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Affiliation(s)
- Masaki Ishikawa
- National Institute for Basic Biology, 38 Nishigonaka, Myodaiji-cho, Okazaki, 444-8585, Japan,
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117
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Cabrera JR, Olcese U, Horabin JI. A balancing act: heterochromatin protein 1a and the Polycomb group coordinate their levels to silence chromatin in Drosophila. Epigenetics Chromatin 2015; 8:17. [PMID: 25954320 PMCID: PMC4423169 DOI: 10.1186/s13072-015-0010-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/15/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The small non-histone protein Heterochromatin protein 1a (HP1a) plays a vital role in packaging chromatin, most notably in forming constitutive heterochromatin at the centromeres and telomeres. A second major chromatin regulating system is that of the Polycomb/trithorax groups of genes which, respectively, maintain the repressed/activated state of euchromatin. Recent analyses suggest they affect the expression of a multitude of genes, beyond the homeotics whose alteration in expression lead to their initial discovery. RESULTS Our data suggest that early in Drosophila development, HP1a collaborates with the Polycomb/trithorax groups of proteins to regulate gene expression and that the two chromatin systems do not act separately as convention describes. HP1a affects the levels of both the Polycomb complexes and RNA polymerase II at promoters, as assayed by chromatin immunoprecipitation analysis. Deposition of both the repressive (H3K27me3) and activating (H3K4me3) marks promoted by the Polycomb/trithorax group genes at gene promoters is affected. Additionally, depending on which parent contributes the null mutation of the HP1a gene, the levels of the H3K27me3 and H3K9me3 silencing marks at both promoters and heterochromatin are different. Changes in levels of the H3K27me3 and H3K9me3 repressive marks show a mostly reciprocal nature. The time around the mid-blastula transition, when the zygotic genome begins to be actively transcribed, appears to be a transition/decision point for setting the levels. CONCLUSIONS We find that HP1a, which is normally critical for the formation of constitutive heterochromatin, also affects the generation of the epigenetic marks of the Polycomb/trithorax groups of proteins, chromatin modifiers which are key to maintaining gene expression in euchromatin. At gene promoters, deposition of both the repressive H3K27me3 and activating H3K4me3 marks of histone modifications shows a dependence on HP1a. Around the mid-blastula transition, when the zygotic genome begins to be actively transcribed, a pivotal decision for the level of silencing appears to take place. This is also when the embryo organizes its genome into heterochromatin and euchromatin. A balance between the HP1a and Polycomb group silencing systems appears to be set for the chromatin types that each system will primarily regulate.
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Affiliation(s)
- Janel R Cabrera
- Department of Biomedical Sciences, College of Medicine, Florida State University, Rm 3300-G, 1115 W, Call St., Tallahassee, FL 32306 USA ; Current Address: Center for Life Sciences, Department of Medicine, Division of Cardiology, Beth Israel Deaconess Medical Center, Rm 917, 3 Blackfan Circle, Boston, MA 02215 USA
| | - Ursula Olcese
- Department of Biomedical Sciences, College of Medicine, Florida State University, Rm 3300-G, 1115 W, Call St., Tallahassee, FL 32306 USA
| | - Jamila I Horabin
- Department of Biomedical Sciences, College of Medicine, Florida State University, Rm 3300-G, 1115 W, Call St., Tallahassee, FL 32306 USA
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Rickabaugh TM, Baxter RM, Sehl M, Sinsheimer JS, Hultin PM, Hultin LE, Quach A, Martínez-Maza O, Horvath S, Vilain E, Jamieson BD. Acceleration of age-associated methylation patterns in HIV-1-infected adults. PLoS One 2015; 10:e0119201. [PMID: 25807146 PMCID: PMC4373843 DOI: 10.1371/journal.pone.0119201] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 01/23/2015] [Indexed: 01/31/2023] Open
Abstract
Patients with treated HIV-1-infection experience earlier occurrence of aging-associated diseases, raising speculation that HIV-1-infection, or antiretroviral treatment, may accelerate aging. We recently described an age-related co-methylation module comprised of hundreds of CpGs; however, it is unknown whether aging and HIV-1-infection exert negative health effects through similar, or disparate, mechanisms. We investigated whether HIV-1-infection would induce age-associated methylation changes. We evaluated DNA methylation levels at >450,000 CpG sites in peripheral blood mononuclear cells (PBMC) of young (20-35) and older (36-56) adults in two separate groups of participants. Each age group for each data set consisted of 12 HIV-1-infected and 12 age-matched HIV-1-uninfected samples for a total of 96 samples. The effects of age and HIV-1 infection on methylation at each CpG revealed a strong correlation of 0.49, p<1 x 10(-200) and 0.47, p<1 x 10(-200). Weighted gene correlation network analysis (WGCNA) identified 17 co-methylation modules; module 3 (ME3) was significantly correlated with age (cor=0.70) and HIV-1 status (cor=0.31). Older HIV-1+ individuals had a greater number of hypermethylated CpGs across ME3 (p=0.015). In a multivariate model, ME3 was significantly associated with age and HIV status (Data set 1: βage=0.007088, p=2.08 x 10(-9); βHIV=0.099574, p=0.0011; Data set 2: βage=0.008762, p=1.27 x 10(-5); βHIV=0.128649, p=0.0001). Using this model, we estimate that HIV-1 infection accelerates age-related methylation by approximately 13.7 years in data set 1 and 14.7 years in data set 2. The genes related to CpGs in ME3 are enriched for polycomb group target genes known to be involved in cell renewal and aging. The overlap between ME3 and an aging methylation module found in solid tissues is also highly significant (Fisher-exact p=5.6 x 10(-6), odds ratio=1.91). These data demonstrate that HIV-1 infection is associated with methylation patterns that are similar to age-associated patterns and suggest that general aging and HIV-1 related aging work through some common cellular and molecular mechanisms. These results are an important first step for finding potential therapeutic targets and novel clinical approaches to mitigate the detrimental effects of both HIV-1-infection and aging.
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Affiliation(s)
- Tammy M Rickabaugh
- Department of Medicine, Division of Hematology/Oncology, AIDS Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Ruth M Baxter
- Department of Human Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Mary Sehl
- Department of Medicine, Division of Hematology/Oncology, AIDS Institute, University of California Los Angeles, Los Angeles, California, United States of America; Biomathematics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Janet S Sinsheimer
- Department of Human Genetics, University of California Los Angeles, Los Angeles, California, United States of America; Biomathematics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America; Department of Biostatistics, School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America
| | - Patricia M Hultin
- Department of Epidemiology, School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America
| | - Lance E Hultin
- Department of Medicine, Division of Hematology/Oncology, AIDS Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Austin Quach
- Department of Human Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Otoniel Martínez-Maza
- Department of Epidemiology, School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America; Departments of Obstetrics and Gynecology, and Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Steve Horvath
- Department of Human Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Eric Vilain
- Department of Human Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Beth D Jamieson
- Department of Medicine, Division of Hematology/Oncology, AIDS Institute, University of California Los Angeles, Los Angeles, California, United States of America
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Lee MC, Spradling AC. The progenitor state is maintained by lysine-specific demethylase 1-mediated epigenetic plasticity during Drosophila follicle cell development. Genes Dev 2015; 28:2739-49. [PMID: 25512561 PMCID: PMC4265677 DOI: 10.1101/gad.252692.114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Progenitors are early lineage cells that proliferate before the onset of terminal differentiation. Although widespread, the epigenetic mechanisms that control the progenitor state and the onset of differentiation remain elusive. By studying Drosophila ovarian follicle cell progenitors, we identified lysine-specific demethylase 1 (lsd1) and CoRest as differentiation regulators using a GAL4∷GFP variegation assay. The follicle cell progenitors in lsd1 or CoRest heterozygotes prematurely lose epigenetic plasticity, undergo the Notch-dependent mitotic-endocycle transition, and stop dividing before a normal number of follicle cells can be produced. Simultaneously reducing the dosage of the histone H3K4 methyltransferase Trithorax reverses these effects, suggesting that an Lsd1/CoRest complex times progenitor differentiation by controlling the stability of H3K4 methylation levels. Individual cells or small clones initially respond to Notch; hence, a critical level of epigenetic stabilization is acquired cell-autonomously and initiates differentiation by making progenitors responsive to pre-existing external signals.
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Affiliation(s)
- Ming-Chia Lee
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution, Baltimore, Maryland 21218, USA
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution, Baltimore, Maryland 21218, USA
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120
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Histone exchange, chromatin structure and the regulation of transcription. Nat Rev Mol Cell Biol 2015; 16:178-89. [DOI: 10.1038/nrm3941] [Citation(s) in RCA: 650] [Impact Index Per Article: 72.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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121
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Ma Y, Kanakousaki K, Buttitta L. How the cell cycle impacts chromatin architecture and influences cell fate. Front Genet 2015; 6:19. [PMID: 25691891 PMCID: PMC4315090 DOI: 10.3389/fgene.2015.00019] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 01/14/2015] [Indexed: 01/17/2023] Open
Abstract
Since the earliest observations of cells undergoing mitosis, it has been clear that there is an intimate relationship between the cell cycle and nuclear chromatin architecture. The nuclear envelope and chromatin undergo robust assembly and disassembly during the cell cycle, and transcriptional and post-transcriptional regulation of histone biogenesis and chromatin modification is controlled in a cell cycle-dependent manner. Chromatin binding proteins and chromatin modifications in turn influence the expression of critical cell cycle regulators, the accessibility of origins for DNA replication, DNA repair, and cell fate. In this review we aim to provide an integrated discussion of how the cell cycle machinery impacts nuclear architecture and vice-versa. We highlight recent advances in understanding cell cycle-dependent histone biogenesis and histone modification deposition, how cell cycle regulators control histone modifier activities, the contribution of chromatin modifications to origin firing for DNA replication, and newly identified roles for nucleoporins in regulating cell cycle gene expression, gene expression memory and differentiation. We close with a discussion of how cell cycle status may impact chromatin to influence cell fate decisions, under normal contexts of differentiation as well as in instances of cell fate reprogramming.
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Affiliation(s)
- Yiqin Ma
- Department of Molecular, Cellular and Developmental Biology, University of Michigan , Ann Arbor, MI, USA
| | - Kiriaki Kanakousaki
- Department of Molecular, Cellular and Developmental Biology, University of Michigan , Ann Arbor, MI, USA
| | - Laura Buttitta
- Department of Molecular, Cellular and Developmental Biology, University of Michigan , Ann Arbor, MI, USA
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122
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Xiao J, Wagner D. Polycomb repression in the regulation of growth and development in Arabidopsis. CURRENT OPINION IN PLANT BIOLOGY 2015; 23:15-24. [PMID: 25449722 DOI: 10.1016/j.pbi.2014.10.003] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/01/2014] [Accepted: 10/06/2014] [Indexed: 05/18/2023]
Abstract
Chromatin state is critical for cell identity and development in multicellular eukaryotes. Among the regulators of chromatin state, Polycomb group (PcG) proteins stand out because of their role in both establishment and maintenance of cell identity. PcG proteins act in two major complexes in metazoans and plants. These complexes function to epigenetically-in a mitotically heritable manner-prevent expression of important developmental regulators at the wrong stage of development or in the wrong tissue. In Arabidopsis, PcG function is required throughout the life cycle from seed germination to embryo formation. Recent studies have expanded our knowledge regarding the biological roles and the regulation of the activity of PcG complexes. In this review, we discuss novel functions of Polycomb repression in plant development as well as advances in understanding PcG complex recruitment, activity regulation and removal in Arabidopsis and other plant species.
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Affiliation(s)
- Jun Xiao
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Doris Wagner
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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123
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Abstract
Epigenetic memory stably maintains and transmits information during genome replication. Recently in Science, Gaydos et al. (2014) show that repressive chromatin marks exhibit transgenerational stability in the absence of chromatin-modifying enzymes in Caenorhabditis elegans, in contrast to work in flies suggesting that such proteins mediate stable inheritance of epigenetic modifications.
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Affiliation(s)
- William G Kelly
- Biology Department, Emory University, Atlanta, GA 30322, USA.
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124
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Abstract
Correct expression of specific sets of genes in time and space ensures the establishment and maintenance of cell identity, which is required for proper development of multicellular organisms. Polycomb and Trithorax group proteins form multisubunit complexes that antagonistically act in epigenetic gene repression and activation, respectively. The traditional view of Polycomb repressive complexes (PRCs) as executors of long-lasting and stable gene repression is being extended by evidence of flexible repression in response to developmental and environmental cues, increasing the complexity of mechanisms that ensure selective and properly timed PRC targeting and release of Polycomb repression. Here, we review advances in understanding of the composition, mechanisms of targeting, and function of plant PRCs and discuss the parallels and differences between plant and animal models.
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Affiliation(s)
- Iva Mozgova
- Department of Plant Biology, Uppsala BioCenter, and Linnean Center for Plant Biology, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden; ,
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125
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Dressler GR, Patel SR. Epigenetics in kidney development and renal disease. Transl Res 2015; 165:166-76. [PMID: 24958601 PMCID: PMC4256142 DOI: 10.1016/j.trsl.2014.04.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/08/2014] [Accepted: 04/10/2014] [Indexed: 11/21/2022]
Abstract
The study of epigenetics is intimately linked and inseparable from developmental biology. Many of the genes that imprint epigenetic information on chromatin function during the specification of cell lineages in the developing embryo. These include the histone methyltransferases and their cofactors of the Polycomb and Trithorax gene families. How histone methylation is established and what regulates the tissue and locus specificity of histone methylation is an emerging area of research. The embryonic kidney is used as a model to understand how DNA-binding proteins can specify cell lineages and how such proteins interact directly with the histone methylation machinery to generate a unique epigenome for particular tissues and cell types. In adult tissues, histone methylation marks must be maintained for normal gene expression patterns. In chronic and acute renal disease, epigenetic marks are being characterized and correlated with the establishment of metabolic memory, in part to explain the persistence of pathologies even when optimal treatment modalities are used. Thus, the state of the epigenome in adult cells must be considered when attempting to alleviate or alter gene expression patterns in disease.
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126
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Choi Y, Mango SE. Hunting for Darwin's gemmules and Lamarck's fluid: Transgenerational signaling and histone methylation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1440-53. [DOI: 10.1016/j.bbagrm.2014.05.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 05/07/2014] [Accepted: 05/13/2014] [Indexed: 01/22/2023]
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127
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Campbell M, Kung HJ, Izumiya Y. Long non-coding RNA and epigenetic gene regulation of KSHV. Viruses 2014; 6:4165-77. [PMID: 25375882 PMCID: PMC4246214 DOI: 10.3390/v6114165] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 10/21/2014] [Accepted: 10/22/2014] [Indexed: 12/22/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV/human herpesvirus 8) is a γ-herpesvirus linked to Kaposi's sarcoma (KS) and two lymphoproliferative disorders, primary effusion lymphoma (PEL or body-cavity B-lymphoma [BCBL]) and a subset of Multicentric Castleman's Disease. During lytic growth, pervasive viral transcription generating a variety of transcripts with uncertain protein-coding potential has been described on a genome-wide scale in β- and γ-herpesviruses. One class of such RNAs is called long non-coding RNAs (lncRNAs). KSHV encodes a viral lncRNA known as polyadenylated nuclear RNA (PAN RNA), a copious early gene product. PAN RNA has been implicated in KSHV gene expression, replication, and immune modulation. PAN RNA expression is required for optimal expression of the entire KSHV lytic gene expression program. Latent KSHV episomes are coated with viral latency-associated nuclear antigen (LANA). LANA rapidly dissociates from episomes during reactivation. Here we review recent studies suggesting that PAN RNA may function as a viral lncRNA, including a role in the facilitation of LANA-episomal dissociation during lytic replication.
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Affiliation(s)
- Mel Campbell
- Department of Dermatology, University of California, Davis, CA 95616, USA.
| | - Hsing-Jien Kung
- UC Davis Comprehensive Cancer Center, University of California, Davis, CA 95616, USA.
| | - Yoshihiro Izumiya
- Department of Dermatology, University of California, Davis, CA 95616, USA.
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128
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Petruk S, Black KL, Kovermann SK, Brock HW, Mazo A. Stepwise histone modifications are mediated by multiple enzymes that rapidly associate with nascent DNA during replication. Nat Commun 2014; 4:2841. [PMID: 24276476 PMCID: PMC3874871 DOI: 10.1038/ncomms3841] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 10/29/2013] [Indexed: 11/10/2022] Open
Abstract
The mechanism of epigenetic inheritance following DNA replication may involve dissociation of chromosomal proteins from parental DNA and reassembly on daughter strands in a specific order. Here we investigated the behavior of different types of chromosomal proteins using newly developed methods that allow assessment of the assembly of proteins during DNA replication. Unexpectedly, most chromatin-modifying proteins tested, including methylases, demethylases, acetyltransferases and a deacetylase, are found in close proximity to PCNA or associate with short nascent DNA. Histone modifications occur in a temporal order following DNA replication, mediated by complex activities of different enzymes. In contrast, components of several major nucleosome remodeling complexes are dissociated from parental DNA, and are later recruited to nascent DNA following replication. Epigenetic inheritance of gene expression patterns may require many aspects of chromatin structure to remain in close proximity to the replication complex followed by re-assembly on nascent DNA shortly after replication.
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Affiliation(s)
- Svetlana Petruk
- Department of Biochemistry and Molecular Biology and Kimmel Cancer Center, Thomas Jefferson University, 1020 Locust Street, Philadelphia, Pennsylvania 19107, USA
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129
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Komori H, Xiao Q, Janssens DH, Dou Y, Lee CY. Trithorax maintains the functional heterogeneity of neural stem cells through the transcription factor buttonhead. eLife 2014; 3. [PMID: 25285447 PMCID: PMC4221733 DOI: 10.7554/elife.03502] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 10/03/2014] [Indexed: 01/24/2023] Open
Abstract
The mechanisms that maintain the functional heterogeneity of stem cells, which generates diverse differentiated cell types required for organogenesis, are not understood. In this study, we report that Trithorax (Trx) actively maintains the heterogeneity of neural stem cells (neuroblasts) in the developing Drosophila larval brain. trx mutant type II neuroblasts gradually adopt a type I neuroblast functional identity, losing the competence to generate intermediate neural progenitors (INPs) and directly generating differentiated cells. Trx regulates a type II neuroblast functional identity in part by maintaining chromatin in the buttonhead (btd) locus in an active state through the histone methyltransferase activity of the SET1/MLL complex. Consistently, btd is necessary and sufficient for eliciting a type II neuroblast functional identity. Furthermore, over-expression of btd restores the competence to generate INPs in trx mutant type II neuroblasts. Thus, Trx instructs a type II neuroblast functional identity by epigenetically promoting Btd expression, thereby maintaining neuroblast functional heterogeneity. DOI:http://dx.doi.org/10.7554/eLife.03502.001 Whereas the majority of cells in the brain are unable to divide to produce new cells, neural stem cells can divide numerous times and have the potential to become many different types of brain cells. However, between these two extremes there is another group of cells called neural progenitors. These cells can give rise to multiple types of neurons but, in contrast to stem cells, they can undergo only a limited number of divisions. Many of the molecular mechanisms by which stem cells give rise to progenitors are similar in mammals and in the fruit fly Drosophila. In the brains of fly larvae, a subset of neural stem cells called type II neuroblasts give rise to ‘intermediate neural progenitors’, each of which can divide between four and six times. Every division generates a replacement intermediate neural progenitor and a cell called a ganglion mother cell, which divides one last time to produce two brain cells. Thus, intermediate neural progenitors increase the overall output of cells derived from every division of a type II neuroblast. The ability of type II neuroblasts to generate intermediate neural progenitors is important for development. Loss of this ability will result in a shortage of cells, disrupting brain development, while the faulty generation of intermediate neural progenitors will result in the formation of tumors. Now, using Drosophila brain cells cultured in the laboratory, Komori et al. show that an evolutionarily conserved enzyme called Trithorax has an important role in maintaining this ability. Trithorax acts through a protein called Buttonhead. The role of Buttonhead in regulating intermediate neural progenitors has also been identified by Xie et al. Komori et al. show that type II neuroblasts that lack Trithorax activity lose their unique identity and behave as type I neuroblasts, which never generate intermediate neural progenitors. Trithorax maintains the cellular memory of a type II neuroblast by keeping regions of chromatin—a macromolecule made of DNA and proteins called histones—in an active state. These regions contain key genes, such as the gene for Buttonhead. Re-introducing Buttonhead in type II neuroblasts that lack Trithorax activity can reinstate their ability to produce intermediate neural progenitors. DOI:http://dx.doi.org/10.7554/eLife.03502.002
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Affiliation(s)
- Hideyuki Komori
- Center for Stem Cell Biology, Life Sciences Institute, University of Michigan Medical School, Ann Arbor, United States
| | - Qi Xiao
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Derek H Janssens
- Program in Cell and Molecular Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Yali Dou
- Department of Pathology, University of Michigan Medical School, Ann Arbor, United States
| | - Cheng-Yu Lee
- Center for Stem Cell Biology, Life Sciences Institute, University of Michigan Medical School, Ann Arbor, United States
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130
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Bheda P, Schneider R. Epigenetics reloaded: the single-cell revolution. Trends Cell Biol 2014; 24:712-23. [PMID: 25283892 DOI: 10.1016/j.tcb.2014.08.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/27/2014] [Accepted: 08/28/2014] [Indexed: 01/15/2023]
Abstract
Mechanistically, how epigenetic states are inherited through cellular divisions remains an important open question in the chromatin field and beyond. Defining the heritability of epigenetic states and the underlying chromatin-based mechanisms within a population of cells is complicated due to cell heterogeneity combined with varying levels of stability of these states; thus, efforts must be focused toward single-cell analyses. The approaches presented here constitute the forefront of epigenetics research at the single-cell level using classic and innovative methods to dissect epigenetics mechanisms from the limited material available in a single cell. This review further outlines exciting future avenues of research to address the significance of epigenetic heterogeneity and the contributions of microfluidics technologies to single-cell isolation and analysis.
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Affiliation(s)
- Poonam Bheda
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104/Inserm U964/Université de Strasbourg, 67400 Illkirch, France
| | - Robert Schneider
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104/Inserm U964/Université de Strasbourg, 67400 Illkirch, France.
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131
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Gaydos LJ, Wang W, Strome S. Gene repression. H3K27me and PRC2 transmit a memory of repression across generations and during development. Science 2014; 345:1515-8. [PMID: 25237104 DOI: 10.1126/science.1255023] [Citation(s) in RCA: 196] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
For proper development, cells must retain patterns of gene expression and repression through cell division. Repression via methylation of histone H3 on Lys27 (H3K27me) by Polycomb repressive complex 2 (PRC2) is conserved, but its transmission is not well understood. Our studies suggest that PRC2 represses the X chromosomes in Caenorhabditis elegans germ cells, and this repression is transmitted to embryos by both sperm and oocytes. By generating embryos containing some chromosomes with and some without H3K27me, we show that, without PRC2, H3K27me is transmitted to daughter chromatids through several rounds of cell division. In embryos with PRC2, a mosaic H3K27me pattern persists through embryogenesis. These results demonstrate that H3K27me and PRC2 each contribute to epigenetically transmitting the memory of repression across generations and during development.
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Affiliation(s)
- Laura J Gaydos
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA
| | - Wenchao Wang
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Susan Strome
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA. Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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132
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Campos EI, Stafford JM, Reinberg D. Epigenetic inheritance: histone bookmarks across generations. Trends Cell Biol 2014; 24:664-74. [PMID: 25242115 DOI: 10.1016/j.tcb.2014.08.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 08/13/2014] [Accepted: 08/14/2014] [Indexed: 12/22/2022]
Abstract
Multiple circuitries ensure that cells respond correctly to the environmental cues within defined cellular programs. There is increasing evidence suggesting that cellular memory for these adaptive processes can be passed on through cell divisions and generations. However, the mechanisms by which this epigenetic information is transferred remain elusive, largely because it requires that such memory survive through gross chromatin remodeling events during DNA replication, mitosis, meiosis, and developmental reprogramming. Elucidating the processes by which epigenetic information survives and is transmitted is a central challenge in biology. In this review, we consider recent advances in understanding mechanisms of epigenetic inheritance with a focus on histone segregation at the replication fork, and how an epigenetic memory may get passed through the paternal lineage.
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Affiliation(s)
- Eric I Campos
- Howard Hughes Medical Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - James M Stafford
- Howard Hughes Medical Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Danny Reinberg
- Howard Hughes Medical Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
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133
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Gurard-Levin ZA, Almouzni G. Histone modifications and a choice of variant: a language that helps the genome express itself. F1000PRIME REPORTS 2014; 6:76. [PMID: 25343033 PMCID: PMC4166940 DOI: 10.12703/p6-76] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covalent post-translational modifications on histones impact chromatin structure and function. Their misfunction, along with perturbations or mutations in genes that regulate their dynamic status, has been observed in several diseases. Thus, targeting histone modifications represents attractive opportunities for therapeutic intervention and biomarker discovery. The best approach to address this challenge is to paint a comprehensive picture integrating the growing number of modifications on individual residues and their combinatorial association, the corresponding modifying enzymes, and effector proteins that bind modifications. Furthermore, how they are imposed in a distinct manner during the cell cycle and on specific histone variants are important dimensions to consider. Firstly, this report highlights innovative technologies used to characterize histone modifications, and the corresponding enzymes and effector proteins. Secondly, we examine the recent progress made in understanding the dynamics and maintenance of histone modifications on distinct variants. We also discuss their roles as potential carriers of epigenetic information. Finally, we provide examples of initiatives to exploit histone modifications in cancer management, with the potential for new therapeutic opportunities.
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Affiliation(s)
- Zachary A. Gurard-Levin
- Institut Curie, Centre de RechercheParis, F-75248France
- CNRS, UMR3664Paris, F-75248France
- Équipe Labellisée Ligue contre le Cancer, UMR3664Paris, F-75248France
- UPMC, UMR3664Paris, F-75248France
- Sorbonne University, PSLParisFrance
| | - Geneviève Almouzni
- Institut Curie, Centre de RechercheParis, F-75248France
- CNRS, UMR3664Paris, F-75248France
- Équipe Labellisée Ligue contre le Cancer, UMR3664Paris, F-75248France
- UPMC, UMR3664Paris, F-75248France
- Sorbonne University, PSLParisFrance
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134
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Yao Y, Des Marais TL, Costa M. Chromatin Memory in the Development of Human Cancers. GENE TECHNOLOGY 2014; 3:114. [PMID: 25606572 PMCID: PMC4297643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cancer is a complex disease with acquired genomic and epigenomic alterations that affect cell proliferation, viability and invasiveness. Almost all the epigenetic mechanisms including cytosine methylation and hydroxymethylation, chromatin remodeling and non-coding RNAs have been found associate with carcinogenesis and cancer specific expression profile. Altered histone modification as an epigenetic hallmark is frequently found in tumors. Understanding the epigenetic alterations induced by carcinogens or infectious agents may help us understand early epigenetic changes prior to the development of cancer. In this review, we focus on chromatin remodeling and the associated histone modifiers in the development of cancer; the application of these modifiers as a cancer therapy target in different clinical trial phases is also discussed.
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Affiliation(s)
- Yixin Yao
- Department of Environmental Medicine New York University, New York, USA,Corresponding author: Yixin Yao, Department of Environmental Medicine, New York University, New York, USA; Tel: 845-731-3517;
| | | | - Max Costa
- Department of Environmental Medicine New York University, New York, USA,Department of Biochemistry and Molecular Pharmacology, New York University Langone Medical Center, Tuxedo, New York, USA
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135
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Shpargel KB, Starmer J, Yee D, Pohlers M, Magnuson T. KDM6 demethylase independent loss of histone H3 lysine 27 trimethylation during early embryonic development. PLoS Genet 2014; 10:e1004507. [PMID: 25101834 PMCID: PMC4125042 DOI: 10.1371/journal.pgen.1004507] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 05/29/2014] [Indexed: 02/06/2023] Open
Abstract
The early mammalian embryo utilizes histone H3 lysine 27 trimethylation (H3K27me3) to maintain essential developmental genes in a repressive chromatin state. As differentiation progresses, H3K27me3 is removed in a distinct fashion to activate lineage specific patterns of developmental gene expression. These rapid changes in early embryonic chromatin environment are thought to be dependent on H3K27 demethylases. We have taken a mouse genetics approach to remove activity of both H3K27 demethylases of the Kdm6 gene family, Utx (Kdm6a, X-linked gene) and Jmjd3 (Kdm6b, autosomal gene). Male embryos null for active H3K27 demethylation by the Kdm6 gene family survive to term. At mid-gestation, embryos demonstrate proper patterning and activation of Hox genes. These male embryos retain the Y-chromosome UTX homolog, UTY, which cannot demethylate H3K27me3 due to mutations in catalytic site of the Jumonji-C domain. Embryonic stem (ES) cells lacking all enzymatic KDM6 demethylation exhibit a typical decrease in global H3K27me3 levels with differentiation. Retinoic acid differentiations of these ES cells demonstrate loss of H3K27me3 and gain of H3K4me3 to Hox promoters and other transcription factors, and induce expression similar to control cells. A small subset of genes exhibit decreased expression associated with reduction of promoter H3K4me3 and some low-level accumulation of H3K27me3. Finally, Utx and Jmjd3 mutant mouse embryonic fibroblasts (MEFs) demonstrate dramatic loss of H3K27me3 from promoters of several Hox genes and transcription factors. Our results indicate that early embryonic H3K27me3 repression can be alleviated in the absence of active demethylation by the Kdm6 gene family.
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Affiliation(s)
- Karl B. Shpargel
- Department of Genetics, Carolina Center for Genome Sciences, and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Joshua Starmer
- Department of Genetics, Carolina Center for Genome Sciences, and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Della Yee
- Department of Genetics, Carolina Center for Genome Sciences, and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Michael Pohlers
- Department of Genetics, Carolina Center for Genome Sciences, and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Terry Magnuson
- Department of Genetics, Carolina Center for Genome Sciences, and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
- * E-mail:
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136
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Engelhorn J, Blanvillain R, Carles CC. Gene activation and cell fate control in plants: a chromatin perspective. Cell Mol Life Sci 2014; 71:3119-37. [PMID: 24714879 PMCID: PMC11113918 DOI: 10.1007/s00018-014-1609-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 03/10/2014] [Accepted: 03/12/2014] [Indexed: 01/02/2023]
Abstract
In plants, environment-adaptable organogenesis extends throughout the lifespan, and iterative development requires repetitive rounds of activation and repression of several sets of genes. Eukaryotic genome compaction into chromatin forms a physical barrier for transcription; therefore, induction of gene expression requires alteration in chromatin structure. One of the present great challenges in molecular and developmental biology is to understand how chromatin is brought from a repressive to permissive state on specific loci and in a very specific cluster of cells, as well as how this state is further maintained and propagated through time and cell division in a cell lineage. In this review, we report recent discoveries implementing our knowledge on chromatin dynamics that modulate developmental gene expression. We also discuss how new data sets highlight plant specificities, likely reflecting requirement for a highly dynamic chromatin.
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Affiliation(s)
- Julia Engelhorn
- Université Grenoble Alpes, UMR5168, 38041, Grenoble, France,
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137
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Rissman EF, Adli M. Minireview: transgenerational epigenetic inheritance: focus on endocrine disrupting compounds. Endocrinology 2014; 155:2770-80. [PMID: 24885575 PMCID: PMC4098001 DOI: 10.1210/en.2014-1123] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The idea that what we eat, feel, and experience influences our physical and mental state and can be transmitted to our offspring and even to subsequent generations has been in the popular realm for a long time. In addition to classic gene mutations, we now recognize that some mechanisms for inheritance do not require changes in DNA. The field of epigenetics has provided a new appreciation for the variety of ways biological traits can be transmitted to subsequent generations. Thus, transgenerational epigenetic inheritance has emerged as a new area of research. We have four goals for this minireview. First, we describe the topic and some of the nomenclature used in the literature. Second, we explain the major epigenetic mechanisms implicated in transgenerational inheritance. Next, we examine some of the best examples of transgenerational epigenetic inheritance, with an emphasis on those produced by exposing the parental generation to endocrine-disrupting compounds (EDCs). Finally, we discuss how whole-genome profiling approaches can be used to identify aberrant epigenomic features and gain insight into the mechanism of EDC-mediated transgenerational epigenetic inheritance. Our goal is to educate readers about the range of possible epigenetic mechanisms that exist and encourage researchers to think broadly and apply multiple genomic and epigenomic technologies to their work.
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Affiliation(s)
- Emilie F Rissman
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908
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138
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Kahn TG, Stenberg P, Pirrotta V, Schwartz YB. Combinatorial interactions are required for the efficient recruitment of pho repressive complex (PhoRC) to polycomb response elements. PLoS Genet 2014; 10:e1004495. [PMID: 25010632 PMCID: PMC4091789 DOI: 10.1371/journal.pgen.1004495] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 05/23/2014] [Indexed: 12/20/2022] Open
Abstract
Polycomb Group (PcG) proteins are epigenetic repressors that control metazoan development and cell differentiation. In Drosophila, PcG proteins form five distinct complexes targeted to genes by Polycomb Response Elements (PREs). Of all PcG complexes PhoRC is the only one that contains a sequence-specific DNA binding subunit (PHO or PHOL), which led to a model that places PhoRC at the base of the recruitment hierarchy. Here we demonstrate that in vivo PHO is preferred to PHOL as a subunit of PhoRC and that PHO and PHOL associate with PREs and a subset of transcriptionally active promoters. Although the binding to the promoter sites depends on the quality of recognition sequences, the binding to PREs does not. Instead, the efficient recruitment of PhoRC to PREs requires the SFMBT subunit and crosstalk with Polycomb Repressive Complex 1. We find that human YY1 protein, the ortholog of PHO, binds sites at active promoters in the human genome but does not bind most PcG target genes, presumably because the interactions involved in the targeting to Drosophila PREs are lost in the mammalian lineage. We conclude that the recruitment of PhoRC to PREs is based on combinatorial interactions and propose that such a recruitment strategy is important to attenuate the binding of PcG proteins when the target genes are transcriptionally active. Our findings allow the appropriate placement of PhoRC in the PcG recruitment hierarchy and provide a rationale to explain why YY1 is unlikely to serve as a general recruiter of mammalian Polycomb complexes despite its reported ability to participate in PcG repression in flies. Polycomb Group (PcG) proteins are epigenetic repressors essential for development and cell differentiation. PcG proteins form five complexes targeted to specific genes by Polycomb Response Elements (PREs). How PcG complexes are recruited to PREs is poorly understood. Here we investigate the recruitment of PhoRC, a seemingly simple case of a complex that contains a sequence-specific DNA binding subunit: PHO (or the related protein PHOL). Unexpectedly, we find that the sequence specific binding of PHO is not a primary determinant for recruitment of PhoRC to PRE, which depends on the non-DNA binding subunit SFMBT and cross-talk with another PcG complex, PRC1. The binding of PhoRC is helped by PRC1 and, in turn, may stabilize the binding of PRC1. We propose that the recruitment based on combinatorial interactions enables the conditional binding of PcG proteins, which is important for switching the state of the target genes from repressed to active. The critical role of the cross-talk between PhoRC and PRC1 is further supported by the finding that in mammals, where the protein domains linking the two complexes are missing, the PHO ortholog YY1 has no implication in PcG repression, despite 100% conservation between DNA binding domains of YY1 and PHO.
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Affiliation(s)
- Tatyana G. Kahn
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey, United States of America
| | - Per Stenberg
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Computational Life Science Cluster (CLiC), Umeå University, Umeå, Sweden
| | - Vincenzo Pirrotta
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey, United States of America
- * E-mail: (VP); (YBS)
| | - Yuri B. Schwartz
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey, United States of America
- * E-mail: (VP); (YBS)
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139
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Abstract
Along the lines of established players like chromatin modifiers and transcription factors, noncoding RNA (ncRNA) are now widely accepted as one of the key regulatory molecules in epigenetic regulation of transcription. With increasing evidence of ncRNAs in the establishment of gene silencing through their ability to interact with major chromatin modifiers, in the current review, we discuss their prospective role in the area of inheritance and maintenance of these established silenced states which can be reversible or irreversible in nature. In addition, we attempt to understand and speculate how these RNA dependent or independent maintenance mechanisms differ between each other in a developmental stage, tissue, and gene-specific manner in different biological contexts by utilizing known/unknown regulatory factors.
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Affiliation(s)
- Tanmoy Mondal
- Department of Medical Genetics, Institute of Biomedicine, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 9A, 40530, Gothenburg, Sweden
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140
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Abstract
The development of the mammalian kidney has been studied at the genetic, biochemical, and cell biological level for more than 40 years. As such, detailed mechanisms governing early patterning, cell lineages, and inductive interactions have been well described. How genes interact to specify the renal epithelial cells of the nephrons and how this specification is relevant to maintaining normal renal function is discussed. Implicit in the development of the kidney are epigenetic mechanisms that mark renal cell types and connect certain developmental regulatory factors to chromatin modifications that control gene expression patterns and cellular physiology. In adults, such regulatory factors and their epigenetic pathways may function in regeneration and may be disturbed in disease processes.
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141
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Steffen PA, Ringrose L. What are memories made of? How Polycomb and Trithorax proteins mediate epigenetic memory. Nat Rev Mol Cell Biol 2014; 15:340-56. [PMID: 24755934 DOI: 10.1038/nrm3789] [Citation(s) in RCA: 249] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In any biological system with memory, the state of the system depends on its history. Epigenetic memory maintains gene expression states through cell generations without a change in DNA sequence and in the absence of initiating signals. It is immensely powerful in biological systems - it adds long-term stability to gene expression states and increases the robustness of gene regulatory networks. The Polycomb group (PcG) and Trithorax group (TrxG) proteins can confer long-term, mitotically heritable memory by sustaining silent and active gene expression states, respectively. Several recent studies have advanced our understanding of the molecular mechanisms of this epigenetic memory during DNA replication and mitosis.
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Affiliation(s)
- Philipp A Steffen
- Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Leonie Ringrose
- Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
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142
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Han SK, Wagner D. Role of chromatin in water stress responses in plants. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2785-99. [PMID: 24302754 PMCID: PMC4110454 DOI: 10.1093/jxb/ert403] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
As sessile organisms, plants are exposed to environmental stresses throughout their life. They have developed survival strategies such as developmental and morphological adaptations, as well as physiological responses, to protect themselves from adverse environments. In addition, stress sensing triggers large-scale transcriptional reprogramming directed at minimizing the deleterious effect of water stress on plant cells. Here, we review recent findings that reveal a role of chromatin in water stress responses. In addition, we discuss data in support of the idea that chromatin remodelling and modifying enzymes may be direct targets of stress signalling pathways. Modulation of chromatin regulator activity by these signaling pathways may be critical in minimizing potential trade-offs between growth and stress responses. Alterations in the chromatin organization and/or in the activity of chromatin remodelling and modifying enzymes may furthermore contribute to stress memory. Mechanistic insight into these phenomena derived from studies in model plant systems should allow future engineering of broadly drought-tolerant crop plants that do not incur unnecessary losses in yield or growth.
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Affiliation(s)
- Soon-Ki Han
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Doris Wagner
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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143
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Somer RA, Thummel CS. Epigenetic inheritance of metabolic state. Curr Opin Genet Dev 2014; 27:43-7. [PMID: 24846842 DOI: 10.1016/j.gde.2014.03.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 03/17/2014] [Indexed: 12/24/2022]
Abstract
As the incidence of complex metabolic disease increases in developed countries, so too does the need to understand the causes and risk factors for these disorders. In addition to the well-known contribution of genetics and environment to metabolic dysfunction, many studies have demonstrated that a significant degree of non-genetic heritable risk can be transmitted from parents to offspring over multiple generations. Understanding the mechanisms by which this occurs could change how we study and treat complex metabolic disorders. In this review, we summarize recent advances in this field utilizing Drosophila, mice, and humans, and propose potential molecular mechanisms that underlie the transgenerational inheritance of metabolic state.
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Affiliation(s)
- Rebecca A Somer
- Department of Human Genetics, University of Utah School of Medicine, 15 N 2030 E, Rm 2100, Salt Lake City, UT 84112, USA
| | - Carl S Thummel
- Department of Human Genetics, University of Utah School of Medicine, 15 N 2030 E, Rm 2100, Salt Lake City, UT 84112, USA.
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144
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A rapid and efficient method to purify proteins at replication forks under native conditions. Biotechniques 2014; 55:204-6. [PMID: 24107252 DOI: 10.2144/000114089] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 08/14/2013] [Indexed: 11/23/2022] Open
Abstract
Tools for studying replication fork dynamics are critical for dissecting the mechanisms of DNA replication, DNA repair, histone deposition, and epigenetic memory. Isolation of protein on nascent DNA (iPOND) is an elegant method for purifying replication fork proteins. Here, we present accelerated native iPOND (aniPOND), a simplification of the iPOND procedure with improved protein yield. Cell membrane lysis and nuclei harvesting are combined in one step to reduce washes and minimize sample loss. A mild nuclei lysis protocol is then used to better preserve DNA-protein complexes. aniPOND is faster than iPOND, avoids formaldehyde cross-linking, and improves protein yield 5- and 20-fold for the CAF1-complex or PCNA respectively. Moreover, using aniPOND, but not iPOND, we could detect the polycomb repressive complex 2 (PRC2) components SUZ12, EZH2, and RBBP4 at replication forks. This faster, higher-yield method will facilitate MS analysis of replication fork complexes.
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145
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Miao F, Chen Z, Genuth S, Paterson A, Zhang L, Wu X, Li SM, Cleary P, Riggs A, Harlan DM, Lorenzi G, Kolterman O, Sun W, Lachin JM, Natarajan R. Evaluating the role of epigenetic histone modifications in the metabolic memory of type 1 diabetes. Diabetes 2014; 63:1748-62. [PMID: 24458354 PMCID: PMC3994951 DOI: 10.2337/db13-1251] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We assessed whether epigenetic histone posttranslational modifications are associated with the prolonged beneficial effects (metabolic memory) of intensive versus conventional therapy during the Diabetes Control and Complications Trial (DCCT) on the progression of microvascular outcomes in the long-term Epidemiology of Diabetes Interventions and Complications (EDIC) study. We performed chromatin immunoprecipitation linked to promoter tiling arrays to profile H3 lysine-9 acetylation (H3K9Ac), H3 lysine-4 trimethylation (H3K4Me3), and H3K9Me2 in blood monocytes and lymphocytes obtained from 30 DCCT conventional treatment group subjects (case subjects: mean DCCT HbA1c level >9.1% [76 mmol/mol] and progression of retinopathy or nephropathy by EDIC year 10 of follow-up) versus 30 DCCT intensive treatment subjects (control subjects: mean DCCT HbA1c level <7.3% [56 mmol/mol] and without progression of retinopathy or nephropathy). Monocytes from case subjects had statistically greater numbers of promoter regions with enrichment in H3K9Ac (active chromatin mark) compared with control subjects (P = 0.0096). Among the patients in the two groups combined, monocyte H3K9Ac was significantly associated with the mean HbA1c level during the DCCT and EDIC (each P < 2.2E-16). Of note, the top 38 case hyperacetylated promoters (P < 0.05) included >15 genes related to the nuclear factor-κB inflammatory pathway and were enriched in genes related to diabetes complications. These results suggest an association between HbA1c level and H3K9Ac, and a possible epigenetic explanation for metabolic memory in humans.
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Affiliation(s)
- Feng Miao
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
| | - Zhuo Chen
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
| | - Saul Genuth
- School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Andrew Paterson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Lingxiao Zhang
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
| | - Xiwei Wu
- Department of Molecular and Cellular Biology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
| | - Sierra Min Li
- Department of Biostatistics, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
| | - Patricia Cleary
- The Biostatistics Center, George Washington University, Washington, DC
| | - Arthur Riggs
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
| | - David M. Harlan
- Department of Medicine, University of Massachusetts School of Medicine, Worcester, MA
| | - Gayle Lorenzi
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Orville Kolterman
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Wanjie Sun
- The Biostatistics Center, George Washington University, Washington, DC
| | - John M. Lachin
- The Biostatistics Center, George Washington University, Washington, DC
| | - Rama Natarajan
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA
- Corresponding author: Rama Natarajan,
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146
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Tie F, Banerjee R, Saiakhova AR, Howard B, Monteith KE, Scacheri PC, Cosgrove MS, Harte PJ. Trithorax monomethylates histone H3K4 and interacts directly with CBP to promote H3K27 acetylation and antagonize Polycomb silencing. Development 2014; 141:1129-39. [PMID: 24550119 DOI: 10.1242/dev.102392] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Trithorax (TRX) antagonizes epigenetic silencing by Polycomb group (PcG) proteins, stimulates enhancer-dependent transcription, and establishes a 'cellular memory' of active transcription of PcG-regulated genes. The mechanisms underlying these TRX functions remain largely unknown, but are presumed to involve its histone H3K4 methyltransferase activity. We report that the SET domains of TRX and TRX-related (TRR) have robust histone H3K4 monomethyltransferase activity in vitro and that Tyr3701 of TRX and Tyr2404 of TRR prevent them from being trimethyltransferases. The trx(Z11) missense mutation (G3601S), which abolishes H3K4 methyltransferase activity in vitro, reduces the H3K4me1 but not the H3K4me3 level in vivo. trx(Z11) also suppresses the impaired silencing phenotypes of the Pc(3) mutant, suggesting that H3K4me1 is involved in antagonizing Polycomb silencing. Polycomb silencing is also antagonized by TRX-dependent H3K27 acetylation by CREB-binding protein (CBP). We show that perturbation of Polycomb silencing by TRX overexpression requires CBP. We also show that TRX and TRR are each physically associated with CBP in vivo, that TRX binds directly to the CBP KIX domain, and that the chromatin binding patterns of TRX and TRR are highly correlated with CBP and H3K4me1 genome-wide. In vitro acetylation of H3K27 by CBP is enhanced on K4me1-containing H3 substrates, and independently altering the H3K4me1 level in vivo, via the H3K4 demethylase LSD1, produces concordant changes in H3K27ac. These data indicate that the catalytic activities of TRX and CBP are physically coupled and suggest that both activities play roles in antagonizing Polycomb silencing, stimulating enhancer activity and cellular memory.
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Affiliation(s)
- Feng Tie
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
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147
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Kolybaba A, Classen AK. Sensing cellular states--signaling to chromatin pathways targeting Polycomb and Trithorax group function. Cell Tissue Res 2014; 356:477-93. [PMID: 24728925 DOI: 10.1007/s00441-014-1824-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Accepted: 01/22/2014] [Indexed: 02/06/2023]
Abstract
Cells respond to extra- and intra-cellular signals by dynamically changing their gene expression patterns. After termination of the original signal, new expression patterns are maintained by epigenetic DNA and histone modifications. This represents a powerful mechanism that enables long-term phenotypic adaptation to transient signals. Adaptation of epigenetic landscapes is important for mediating cellular differentiation during development and allows adjustment to altered environmental conditions throughout life. Work over the last decade has begun to elucidate the way that extra- and intra-cellular signals lead to changes in gene expression patterns by directly modulating the function of chromatin-associated proteins. Here, we review key signaling-to-chromatin pathways that are specifically thought to target Polycomb and Trithorax group complexes, a classic example of epigenetically acting gene silencers and activators important in development, stem cell differentiation and cancer. We discuss the influence that signals triggered by kinase cascades, metabolic fluctuations and cell-cycle dynamics have on the function of these protein complexes. Further investigation into these pathways will be important for understanding the mechanisms that maintain epigenetic stability and those that promote epigenetic plasticity.
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Affiliation(s)
- Addie Kolybaba
- Ludwig Maximilians University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152, Planegg-Martinsried, Germany
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148
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Rivera C, Gurard-Levin ZA, Almouzni G, Loyola A. Histone lysine methylation and chromatin replication. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1433-9. [PMID: 24686120 DOI: 10.1016/j.bbagrm.2014.03.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/12/2014] [Accepted: 03/20/2014] [Indexed: 01/20/2023]
Abstract
In eukaryotic organisms, the replication of the DNA sequence and its organization into chromatin are critical to maintain genome integrity. Chromatin components, such as histone variants and histone post-translational modifications, along with the higher-order chromatin structure, impact several DNA metabolic processes, including replication, transcription, and repair. In this review we focus on lysine methylation and the relationships between this histone mark and chromatin replication. We first describe studies implicating lysine methylation in regulating early steps in the replication process. We then discuss chromatin reassembly following replication fork passage, where the incorporation of a combination of newly synthesized histones and parental histones can impact the inheritance of lysine methylation marks on the daughter strands. Finally, we elaborate on how the inheritance of lysine methylation can impact maintenance of the chromatin landscape, using heterochromatin as a model chromatin domain, and we discuss the potential mechanisms involved in this process.
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Affiliation(s)
| | - Zachary A Gurard-Levin
- Institut Curie, Centre de Recherche, Paris F-75248, France; CNRS, UMR 3664, Paris F-75248, France; Equipe Labellisée Ligue contre le Cancer, UMR 3664, Paris F-75248, France; UPMC, UMR 3664, Paris F-75248, France; Paris Sciences & Lettres, PSL, France
| | - Geneviève Almouzni
- Institut Curie, Centre de Recherche, Paris F-75248, France; CNRS, UMR 3664, Paris F-75248, France; Equipe Labellisée Ligue contre le Cancer, UMR 3664, Paris F-75248, France; UPMC, UMR 3664, Paris F-75248, France; Paris Sciences & Lettres, PSL, France.
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149
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Nascent chromatin capture proteomics determines chromatin dynamics during DNA replication and identifies unknown fork components. Nat Cell Biol 2014; 16:281-93. [PMID: 24561620 DOI: 10.1038/ncb2918] [Citation(s) in RCA: 263] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 01/15/2014] [Indexed: 02/07/2023]
Abstract
To maintain genome function and stability, DNA sequence and its organization into chromatin must be duplicated during cell division. Understanding how entire chromosomes are copied remains a major challenge. Here, we use nascent chromatin capture (NCC) to profile chromatin proteome dynamics during replication in human cells. NCC relies on biotin-dUTP labelling of replicating DNA, affinity purification and quantitative proteomics. Comparing nascent chromatin with mature post-replicative chromatin, we provide association dynamics for 3,995 proteins. The replication machinery and 485 chromatin factors such as CAF-1, DNMT1 and SUV39h1 are enriched in nascent chromatin, whereas 170 factors including histone H1, DNMT3, MBD1-3 and PRC1 show delayed association. This correlates with H4K5K12diAc removal and H3K9me1 accumulation, whereas H3K27me3 and H3K9me3 remain unchanged. Finally, we combine NCC enrichment with experimentally derived chromatin probabilities to predict a function in nascent chromatin for 93 uncharacterized proteins, and identify FAM111A as a replication factor required for PCNA loading. Together, this provides an extensive resource to understand genome and epigenome maintenance.
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150
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Asymmetric distribution of histones during Drosophila male germline stem cell asymmetric divisions. Chromosome Res 2014; 21:255-69. [PMID: 23681658 DOI: 10.1007/s10577-013-9356-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
It has long been known that epigenetic changes are inheritable. However, except for DNA methylation, little is known about the molecular mechanisms of epigenetic inheritance. Many types of stem cells undergo asymmetric cell divisions to generate self-renewed stem cells and daughter cells committed for differentiation. Still, whether and how stem cells retain their epigenetic memory remain questions to be elucidated. During the asymmetric division of Drosophila male germline stem cell (GSC), our recent studies revealed that the preexisting histone 3 (H3) are selectively segregated to the GSC, whereas newly synthesized H3 deposited during DNA replication are enriched in the differentiating daughter cell. We propose a two-step model to explain this asymmetric histone distribution. First, prior to mitosis, preexisting histones and newly synthesized histones are differentially distributed at two sets of sister chromatids. Next, during mitosis, the set of sister chromatids that mainly consist of preexisting histones are segregated to GSCs, while the other set of sister chromatids enriched with newly synthesized histones are partitioned to the daughter cell committed for differentiation. In this review, we apply current knowledge about epigenetic inheritance and asymmetric cell division to inform our discussion of potential molecular mechanisms and the cellular basis underlying this asymmetric histone distribution pattern. We will also discuss whether this phenomenon contributes to the maintenance of stem cell identity and resetting chromatin structure in the other daughter cell for differentiation.
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