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Gibbons MD, Fang Y, Spicola AP, Linzer N, Jones SM, Johnson BR, Li L, Xie M, Bungert J. Enhancer-Mediated Formation of Nuclear Transcription Initiation Domains. Int J Mol Sci 2022; 23:ijms23169290. [PMID: 36012554 PMCID: PMC9409229 DOI: 10.3390/ijms23169290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/14/2022] [Accepted: 08/16/2022] [Indexed: 11/16/2022] Open
Abstract
Enhancers in higher eukaryotes and upstream activating sequences (UASs) in yeast have been shown to recruit components of the RNA polymerase II (Pol II) transcription machinery. At least a fraction of Pol II recruited to enhancers in higher eukaryotes initiates transcription and generates enhancer RNA (eRNA). In contrast, UASs in yeast do not recruit transcription factor TFIIH, which is required for transcription initiation. For both yeast and mammalian systems, it was shown that Pol II is transferred from enhancers/UASs to promoters. We propose that there are two modes of Pol II recruitment to enhancers in higher eukaryotes. Pol II complexes that generate eRNAs are recruited via TFIID, similar to mechanisms operating at promoters. This may involve the binding of TFIID to acetylated nucleosomes flanking the enhancer. The resulting eRNA, together with enhancer-bound transcription factors and co-regulators, contributes to the second mode of Pol II recruitment through the formation of a transcription initiation domain. Transient contacts with target genes, governed by proteins and RNA, lead to the transfer of Pol II from enhancers to TFIID-bound promoters.
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Boldyreva LV, Andreyeva EN, Pindyurin AV. Position Effect Variegation: Role of the Local Chromatin Context in Gene Expression Regulation. Mol Biol 2022. [DOI: 10.1134/s0026893322030049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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Oudinet C, Braikia FZ, Dauba A, Santos JM, Khamlichi AA. Developmental regulation of DNA cytosine methylation at the immunoglobulin heavy chain constant locus. PLoS Genet 2019; 15:e1007930. [PMID: 30779742 PMCID: PMC6380546 DOI: 10.1371/journal.pgen.1007930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 01/03/2019] [Indexed: 12/21/2022] Open
Abstract
DNA cytosine methylation is involved in the regulation of gene expression during development and its deregulation is often associated with disease. Mammalian genomes are predominantly methylated at CpG dinucleotides. Unmethylated CpGs are often associated with active regulatory sequences while methylated CpGs are often linked to transcriptional silencing. Previous studies on CpG methylation led to the notion that transcription initiation is more sensitive to CpG methylation than transcriptional elongation. The immunoglobulin heavy chain (IgH) constant locus comprises multiple inducible constant genes and is expressed exclusively in B lymphocytes. The developmental B cell stage at which methylation patterns of the IgH constant genes are established, and the role of CpG methylation in their expression, are unknown. Here, we find that methylation patterns at most cis-acting elements of the IgH constant genes are established and maintained independently of B cell activation or promoter activity. Moreover, one of the promoters, but not the enhancers, is hypomethylated in sperm and early embryonic cells, and is targeted by different demethylation pathways, including AID, UNG, and ATM pathways. Combined, the data suggest that, rather than being prominently involved in the regulation of the IgH constant locus expression, DNA methylation may primarily contribute to its epigenetic pre-marking.
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Affiliation(s)
- Chloé Oudinet
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Fatima-Zohra Braikia
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Audrey Dauba
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Joana M. Santos
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- * E-mail:
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4
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Khateb M, Azriel A, Levi BZ. The Third Intron of IRF8 Is a Cell-Type-Specific Chromatin Priming Element during Mouse Embryonal Stem Cell Differentiation. J Mol Biol 2019; 431:210-222. [PMID: 30502383 DOI: 10.1016/j.jmb.2018.11.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/07/2018] [Accepted: 11/20/2018] [Indexed: 01/09/2023]
Abstract
Interferon regulatory factor 8 (IRF8) is a nuclear transcription factor that plays a key role in the hierarchical differentiation of hematopoietic stem cells toward monocyte/dendritic cell lineages. Therefore, its expression is mainly limited to bone marrow-derived cells. The molecular mechanisms governing this cell-type-restricted expression have been described. However, the molecular mechanisms that are responsible for its silencing in non-hematopoietic cells are elusive. Recently, we demonstrated a role for IRF8 third intron in restricting its expression in non-hematopoietic cells. Furthermore, we showed that this intron alone is sufficient to promote repressed chromatin a cell-type-specific manner. Here we demonstrate the effect of the IRF8 third intron on chromatin conformation during murine embryonal stem cell differentiation. Using genome editing, we provide data showing that the third intron plays a key role in priming the chromatin state of the IRF8 locus during cell differentiation. It mediates dual regulatory effects in a cell-type-specific mode. It acts as a repressor element governing chromatin state of the IRF8 locus during embryonal stem cell differentiation to cardiomyocytes that are expression-restrictive cells. Conversely, it functions as an activator element that is essential for open chromatin structure during the differentiation of these cells to dendritic cells that are expression-permissive cells. Together, these results point to the role of IRF8 third intron as a cell-type-specific chromatin priming element during embryonal stem cell differentiation. These data add another layer to our understanding of the molecular mechanisms governing misexpression of a cell-type-specific gene such as IRF8.
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Affiliation(s)
- Mamduh Khateb
- Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Aviva Azriel
- Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ben-Zion Levi
- Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
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5
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Bond J, Domaschenz R, Roman-Trufero M, Sabbattini P, Ferreiros-Vidal I, Gerrard G, Asnafi V, Macintyre E, Merkenschlager M, Dillon N. Direct interaction of Ikaros and Foxp1 modulates expression of the G protein-coupled receptor G2A in B-lymphocytes and acute lymphoblastic leukemia. Oncotarget 2018; 7:65923-65936. [PMID: 27588474 PMCID: PMC5323203 DOI: 10.18632/oncotarget.11688] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 08/13/2016] [Indexed: 12/13/2022] Open
Abstract
Ikaros and Foxp1 are transcription factors that play key roles in normal lymphopoiesis and lymphoid malignancies. We describe a novel physical and functional interaction between the proteins, which requires the central zinc finger domain of Ikaros. The Ikaros-Foxp1 interaction is abolished by deletion of this region, which corresponds to the IK6 isoform that is commonly associated with high-risk acute lymphoblastic leukemia (ALL). We also identify the Gpr132 gene, which encodes the orphan G protein-coupled receptor G2A, as a novel target for Foxp1. Increased expression of Foxp1 enhanced Gpr132 transcription and caused cell cycle changes, including G2 arrest. Co-expression of wild-type Ikaros, but not IK6, displaced Foxp1 binding from the Gpr132 gene, reversed the increase in Gpr132 expression and inhibited G2 arrest. Analysis of primary ALL samples revealed a significant increase in GPR132 expression in IKZF1-deleted BCR-ABL negative patients, suggesting that levels of wild-type Ikaros may influence the regulation of G2A in B-ALL. Our results reveal a novel effect of Ikaros haploinsufficiency on Foxp1 functioning, and identify G2A as a potential modulator of the cell cycle in Ikaros-deleted B-ALL.
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Affiliation(s)
- Jonathan Bond
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Campus, London W12 0NN, United Kingdom.,Université Paris Descartes Sorbonne Cité, Institut Necker-Enfants Malades (INEM), Institut National de Recherche Médicale (INSERM), and Laboratory of Onco-Hematology, Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital Necker Enfants-Malades, Paris, France
| | - Renae Domaschenz
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Campus, London W12 0NN, United Kingdom.,Present address: Chromatin and Transcriptional Regulation Group, John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Mónica Roman-Trufero
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Campus, London W12 0NN, United Kingdom
| | - Pierangela Sabbattini
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Campus, London W12 0NN, United Kingdom
| | - Isabel Ferreiros-Vidal
- Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Campus, London W12 0NN, United Kingdom
| | - Gareth Gerrard
- Imperial Molecular Pathology, Imperial College Academic Health Sciences Centre, Hammersmith Campus, London W12 0NN, United Kingdom
| | - Vahid Asnafi
- Université Paris Descartes Sorbonne Cité, Institut Necker-Enfants Malades (INEM), Institut National de Recherche Médicale (INSERM), and Laboratory of Onco-Hematology, Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital Necker Enfants-Malades, Paris, France
| | - Elizabeth Macintyre
- Université Paris Descartes Sorbonne Cité, Institut Necker-Enfants Malades (INEM), Institut National de Recherche Médicale (INSERM), and Laboratory of Onco-Hematology, Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital Necker Enfants-Malades, Paris, France
| | - Matthias Merkenschlager
- Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Campus, London W12 0NN, United Kingdom
| | - Niall Dillon
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Campus, London W12 0NN, United Kingdom
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Wang W, Zheng K, Pei Y, Zhang X. Histone Demethylase JARID1B Is Overexpressed in Osteosarcoma and Upregulates Cyclin D1 Expression via Demethylation of H3K27me3. Oncol Res 2017; 26:373-384. [PMID: 28492139 PMCID: PMC7844678 DOI: 10.3727/096504017x14939809845080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
JARID1B has been proven to be upregulated in many human malignancies and is correlated with tumor progression. However, its expression and clinical significance in osteosarcoma are still unclear. Thus, the aim of this study was to explore the effects of JARID1B in osteosarcoma tumorigenesis and development. In this study, we found that the expression levels of JARID1B in osteosarcoma tissues were significantly higher than those in corresponding noncancerous bone tissues. In addition, JARID1B upregulation occurred more frequently in osteosarcoma specimens from patients with a poor prognosis. After JARID1B transfection in osteosarcoma cells, cell proliferation was significantly promoted in vitro and in vivo. On the contrary, knockdown of JARID1B inhibited cell proliferation in vitro and tumor growth in vivo. JARID1B can also decrease the G0/G1 phase cell numbers and increase the S and G2/M phase cell numbers. We further demonstrated that JARID1B regulates cyclin D1 expression through H3K27me3. These findings indicate that JARID1B may act not only as a novel diagnostic and prognostic marker but also as a potential target for molecular therapy in osteosarcoma.
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Affiliation(s)
- Wei Wang
- Department of Bone and Soft-Tissue Tumor Surgery, Cancer Hospital of China Medical UniversityShenyang, Liaoning ProvinceP.R. China
| | - Ke Zheng
- Department of Bone and Soft-Tissue Tumor Surgery, Cancer Hospital of China Medical UniversityShenyang, Liaoning ProvinceP.R. China
| | - Yi Pei
- Department of Bone and Soft-Tissue Tumor Surgery, Cancer Hospital of China Medical UniversityShenyang, Liaoning ProvinceP.R. China
| | - XiaoJing Zhang
- Department of Bone and Soft-Tissue Tumor Surgery, Cancer Hospital of China Medical UniversityShenyang, Liaoning ProvinceP.R. China
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7
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Beagrie RA, Pombo A. Gene activation by metazoan enhancers: Diverse mechanisms stimulate distinct steps of transcription. Bioessays 2016; 38:881-93. [PMID: 27452946 DOI: 10.1002/bies.201600032] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Enhancers can stimulate transcription by a number of different mechanisms which control different stages of the transcription cycle of their target genes, from recruitment of the transcription machinery to elongation by RNA polymerase. These mechanisms may not be mutually exclusive, as a single enhancer may act through different pathways by binding multiple transcription factors. Multiple enhancers may also work together to regulate transcription of a shared target gene. Most of the evidence supporting different enhancer mechanisms comes from the study of single genes, but new high-throughput experimental frameworks offer the opportunity to integrate and generalize disparate mechanisms identified at single genes. This effort is especially important if we are to fully understand how sequence variation within enhancers contributes to human disease.
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Affiliation(s)
- Robert A Beagrie
- Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max-Delbrück Centre for Molecular Medicine, Berlin-Buch, Germany
| | - Ana Pombo
- Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max-Delbrück Centre for Molecular Medicine, Berlin-Buch, Germany
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8
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Vernimmen D, Bickmore WA. The Hierarchy of Transcriptional Activation: From Enhancer to Promoter. Trends Genet 2016; 31:696-708. [PMID: 26599498 DOI: 10.1016/j.tig.2015.10.004] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/18/2015] [Accepted: 10/15/2015] [Indexed: 12/20/2022]
Abstract
Regulatory elements (enhancers) that are remote from promoters play a critical role in the spatial, temporal, and physiological control of gene expression. Studies on specific loci, together with genome-wide approaches, suggest that there may be many common mechanisms involved in enhancer-promoter communication. Here, we discuss the multiprotein complexes that are recruited to enhancers and the hierarchy of events taking place between regulatory elements and promoters.
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Affiliation(s)
- Douglas Vernimmen
- The Roslin Institute, Developmental Biology Division, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK.
| | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
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9
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Tang K, Peng G, Qiao Y, Song L, Jing N. Intrinsic regulations in neural fate commitment. Dev Growth Differ 2015; 57:109-20. [PMID: 25708399 DOI: 10.1111/dgd.12204] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/11/2014] [Accepted: 12/21/2014] [Indexed: 12/22/2022]
Abstract
Neural fate commitment is an early embryonic event that a group of cells in ectoderm, which do not ingress through primitive streak, acquire a neural fate but not epidermal or mesodermal lineages. Several extracellular signaling pathways initiated by the secreted proteins bone morphogenetic proteins (BMPs), fibroblast growth factors (FGFs), wingless/int class proteins (WNTs) and Nodal play essential roles in the specification of the neural plate. Accumulating evidence from the studies on mouse and pluripotent embryonic stem cells reveals that except for the extracellular signals, the intracellular molecules, including both transcriptional and epigenetic factors, participate in the modulation of neural fate commitment as well. In the review, we mainly focus on recent findings that the initiation of the nervous system is elaborately regulated by the intrinsic programs, which are mediated by transcriptional factors such as Sox2, Zfp521, Sip1 and Pou3f1, as well as epigenetic modifications, including histone methylation/demethylation, histone acetylation/deacetylation, and DNA methylation/demethylation. The discovery of the intrinsic regulatory machineries provides better understanding of the mechanisms by which the neural fate commitment is ensured by the cooperation between extracellular factors and intracellular molecules.
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Affiliation(s)
- Ke Tang
- Institute of Life Science, Nanchang University, Nanchang, Jiangxi, 330031, China
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10
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Larabee SM, Coia H, Jones S, Cheung E, Gallicano GI. miRNA-17 members that target Bmpr2 influence signaling mechanisms important for embryonic stem cell differentiation in vitro and gastrulation in embryos. Stem Cells Dev 2014; 24:354-71. [PMID: 25209090 DOI: 10.1089/scd.2014.0051] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Body axes and germ layers evolve at gastrulation, and in mammals are driven by many genes; however, what orchestrates the genetic pathways during gastrulation remains elusive. Previously, we presented evidence that microRNA-17 (miRNA-17) family members, miR-17-5p, miR-20a, miR-93, and miR-106a were differentially expressed in mouse embryos and functioned to control differentiation of the stem cell population. Here, we identify function(s) that these miRNAs have during gastrulation. Fluorescent in situ hybridization miRNA probes reveal that these miRNAs are localized at the mid/posterior primitive streak (ps) in distinct populations of primitive ectoderm, mesendoderm, and mesoderm. Seven different miRNA prediction algorithms are identified in silico bone morphogenic protein receptor 2 (Bmpr2) as a target of these miRNAs. Bmpr2 is a member of the TGFβ pathway and invokes stage-specific changes during gastrulation. Recently, Bmpr2 was shown regulating cytoskeletal dynamics, cell movement, and invasion. Our previous and current data led to a hypothesis by which members of the miR-17 family influence gastrulation by suppressing Bmpr2 expression at the primitive streak. This suppression influences fate decisions of cells by affecting genes downstream of BMPR2 as well as mesoderm invasion through regulation of actin dynamics.
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Affiliation(s)
- Shannon M Larabee
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center , Washington, District of Columbia
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Abstract
Over the last three decades, studies of the α- and β-globin genes clusters have led to elucidation of the general principles of mammalian gene regulation, such as RNA stability, termination of transcription, and, more importantly, the identification of remote regulatory elements. More recently, detailed studies of α-globin regulation, using both mouse and human loci, allowed the dissection of the sequential order in which transcription factors are recruited to the locus during lineage specification. These studies demonstrated the importance of the remote regulatory elements in the recruitment of RNA polymerase II (PolII) together with their role in the generation of intrachromosomal loops within the locus and the removal of polycomb complexes during differentiation. The multiple roles attributed to remote regulatory elements that have emerged from these studies will be discussed.
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Affiliation(s)
- Douglas Vernimmen
- The Roslin Institute, Developmental Biology Division, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
- * E-mail:
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12
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Zhang Y, Yang H, Guo X, Rong N, Song Y, Xu Y, Lan W, Zhang X, Liu M, Xu Y, Cao C. The PHD1 finger of KDM5B recognizes unmodified H3K4 during the demethylation of histone H3K4me2/3 by KDM5B. Protein Cell 2014; 5:837-50. [PMID: 24952722 PMCID: PMC4225485 DOI: 10.1007/s13238-014-0078-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 05/06/2014] [Indexed: 11/27/2022] Open
Abstract
KDM5B is a histone H3K4me2/3 demethylase. The PHD1 domain of KDM5B is critical for demethylation, but the mechanism underlying the action of this domain is unclear. In this paper, we observed that PHD1KDM5B interacts with unmethylated H3K4me0. Our NMR structure of PHD1KDM5B in complex with H3K4me0 revealed that the binding mode is slightly different from that of other reported PHD fingers. The disruption of this interaction by double mutations on the residues in the interface (L325A/D328A) decreases the H3K4me2/3 demethylation activity of KDM5B in cells by approximately 50% and increases the transcriptional repression of tumor suppressor genes by approximately twofold. These findings imply that PHD1KDM5B may help maintain KDM5B at target genes to mediate the demethylation activities of KDM5B.
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Affiliation(s)
- Yan Zhang
- State Key Laboratory of Bio-organic and Natural Product Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032 China
| | - Huirong Yang
- Institutes of Biomedical Sciences, Fudan University, 130 Dong-An Road, Shanghai, 200032 China
| | - Xue Guo
- Institutes of Biomedical Sciences, Fudan University, 130 Dong-An Road, Shanghai, 200032 China
| | - Naiyan Rong
- State Key Laboratory of Bio-organic and Natural Product Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032 China
| | - Yujiao Song
- State Key Laboratory of Bio-organic and Natural Product Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032 China
| | - Youwei Xu
- Institutes of Biomedical Sciences, Fudan University, 130 Dong-An Road, Shanghai, 200032 China
| | - Wenxian Lan
- State Key Laboratory of Bio-organic and Natural Product Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032 China
| | - Xu Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071 China
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071 China
| | - Yanhui Xu
- Institutes of Biomedical Sciences, Fudan University, 130 Dong-An Road, Shanghai, 200032 China
| | - Chunyang Cao
- State Key Laboratory of Bio-organic and Natural Product Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032 China
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Chang KH, Fang X, Wang H, Huang A, Cao H, Yang Y, Bonig H, Stamatoyannopoulos JA, Papayannopoulou T. Epigenetic modifications and chromosome conformations of the beta globin locus throughout development. Stem Cell Rev Rep 2014; 9:397-407. [PMID: 22374078 DOI: 10.1007/s12015-012-9355-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human embryonic stem cells provide an alternative to using human embryos for studying developmentally regulated gene expression. The co-expression of high levels of embryonic ε and fetal γ globin by the hESC-derived erythroblasts allows the interrogation of ε globin regulation at the transcriptional and epigenetic level which could only be attained previously by studying cell lines or transgenic mice. In this study, we compared the histone modifications across the β globin locus of the undifferentiated hESCs and hESC-, FL-, and mobilized PB CD34(+) cells-derived erythroblasts, which have distinct globin expression patterns corresponding to their developmental stages. We demonstrated that the histone codes employed by the β globin locus are conserved throughout development. Furthermore, in spite of the close proximity of the ε globin promoter, as compared to the β or γ globin promoter, with the LCR, a chromatin loop was also formed between the LCR and the active ε globin promoter, similar to the loop that forms between the β or γ globin promoters and the LCR, in contrary to the previously proposed tracking mechanism.
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Affiliation(s)
- Kai-Hsin Chang
- Department of Medicine, Division of Hematology, University of Washington, NE Pacific St, Box 357710, Seattle, WA 98195, USA
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14
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Fletcher S, Prochownik EV. Small-molecule inhibitors of the Myc oncoprotein. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:525-43. [PMID: 24657798 DOI: 10.1016/j.bbagrm.2014.03.005] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 03/09/2014] [Accepted: 03/12/2014] [Indexed: 01/23/2023]
Abstract
The c-Myc (Myc) oncoprotein is among the most attractive of cancer targets given that it is de-regulated in the majority of tumors and that its inhibition profoundly affects their growth and/or survival. However, its role as a seldom-mutated transcription factor, its lack of enzymatic activity for which suitable pharmaceutical inhibitors could be crafted and its expression by normal cells have largely been responsible for its being viewed as "undruggable". Work over the past several years, however, has begun to reverse this idea by allowing us to view Myc within the larger context of global gene regulatory control. Thus, Myc and its obligate heterodimeric partner, Max, are integral to the coordinated recruitment and post-translational modification of components of the core transcriptional machinery. Moreover, Myc over-expression re-programs numerous critical cellular functions and alters the cell's susceptibility to their inhibition. This new knowledge has therefore served as a framework upon which to develop new pharmaceutical approaches. These include the continuing development of small molecules which act directly to inhibit the critical Myc-Max interaction, those which act indirectly to prevent Myc-directed post-translational modifications necessary to initiate productive transcription and those which inhibit vital pathways upon which the Myc-transformed cell is particularly reliant. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.
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Affiliation(s)
- Steven Fletcher
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, USA; University of Maryland Greenebaum Cancer Center, Baltimore, USA
| | - Edward V Prochownik
- Section of Hematology/Oncology, Children's Hospital of Pittsburgh of UPMC, USA; Department of Microbiology and Molecular Genetics, The University of Pittsburgh School of Medicine, USA; The University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA.
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15
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Sabbattini P, Sjoberg M, Nikic S, Frangini A, Holmqvist PH, Kunowska N, Carroll T, Brookes E, Arthur SJ, Pombo A, Dillon N. An H3K9/S10 methyl-phospho switch modulates Polycomb and Pol II binding at repressed genes during differentiation. Mol Biol Cell 2014; 25:904-15. [PMID: 24430871 PMCID: PMC3952858 DOI: 10.1091/mbc.e13-10-0628] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Polycomb-repressed genes are marked by H3K9me3 and H3K27me3 in pluripotent ES cells, but the effects of this combination are altered by H3S10 phosphorylation in differentiated cells. Acquisition of H3K9me3/S10ph at Polycomb-target genes during differentiation reduces binding of Ezh1 and paused RNA Pol II and affects poising of repressed genes. Methylated histones H3K9 and H3K27 are canonical epigenetic silencing modifications in metazoan organisms, but the relationship between the two modifications has not been well characterized. H3K9me3 coexists with H3K27me3 in pluripotent and differentiated cells. However, we find that the functioning of H3K9me3 is altered by H3S10 phosphorylation in differentiated postmitotic osteoblasts and cycling B cells. Deposition of H3K9me3/S10ph at silent genes is partially mediated by the mitogen- and stress-activated kinases (MSK1/2) and the Aurora B kinase. Acquisition of H3K9me3/S10ph during differentiation correlates with loss of paused S5 phosphorylated RNA polymerase II, which is present on Polycomb-regulated genes in embryonic stem cells. Reduction of the levels of H3K9me3/S10ph by kinase inhibition results in increased binding of RNAPIIS5ph and the H3K27 methyltransferase Ezh1 at silent promoters. Our results provide evidence of a novel developmentally regulated methyl-phospho switch that modulates Polycomb regulation in differentiated cells and stabilizes repressed states.
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Affiliation(s)
- Pierangela Sabbattini
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom Genome Function Group, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom MRC Protein Phosphorylation Unit, Sir James Black Centre, University of Dundee, Dundee DD1 5EH, United Kingdom
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16
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Chen T, Dent SYR. Chromatin modifiers and remodellers: regulators of cellular differentiation. Nat Rev Genet 2013; 15:93-106. [PMID: 24366184 DOI: 10.1038/nrg3607] [Citation(s) in RCA: 449] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cellular differentiation is, by definition, epigenetic. Genome-wide profiling of pluripotent cells and differentiated cells suggests global chromatin remodelling during differentiation, which results in a progressive transition from a fairly open chromatin configuration to a more compact state. Genetic studies in mouse models show major roles for a variety of histone modifiers and chromatin remodellers in key developmental transitions, such as the segregation of embryonic and extra-embryonic lineages in blastocyst stage embryos, the formation of the three germ layers during gastrulation and the differentiation of adult stem cells. Furthermore, rather than merely stabilizing the gene expression changes that are driven by developmental transcription factors, there is emerging evidence that chromatin regulators have multifaceted roles in cell fate decisions.
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Affiliation(s)
- Taiping Chen
- 1] Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center. [2] Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Science Park, 1808 Park Road 1C, Smithville, Texas 78957, USA. [3] The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, USA
| | - Sharon Y R Dent
- 1] Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center. [2] Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Science Park, 1808 Park Road 1C, Smithville, Texas 78957, USA. [3] The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, USA
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17
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Batlle-López A, Cortiguera MG, Rosa-Garrido M, Blanco R, del Cerro E, Torrano V, Wagner SD, Delgado MD. Novel CTCF binding at a site in exon1A of BCL6 is associated with active histone marks and a transcriptionally active locus. Oncogene 2013; 34:246-56. [PMID: 24362533 DOI: 10.1038/onc.2013.535] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 10/01/2013] [Accepted: 11/01/2013] [Indexed: 12/14/2022]
Abstract
BCL6 is a zinc-finger transcriptional repressor, which is highly expressed in germinal centre B-cells and is essential for germinal centre formation and T-dependent antibody responses. Constitutive BCL6 expression is sufficient to produce lymphomas in mice. Deregulated expression of BCL6 due to chromosomal rearrangements, mutations of a negative autoregulatory site in the BCL6 promoter region and aberrant post-translational modifications have been detected in a number of human lymphomas. Tight lineage and temporal regulation of BCL6 is, therefore, required for normal immunity, and abnormal regulation occurs in lymphomas. CCCTC-binding factor (CTCF) is a multi-functional chromatin regulator, which has recently been shown to bind in a methylation-sensitive manner to sites within the BCL6 first intron. We demonstrate a novel CTCF-binding site in BCL6 exon1A within a potential CpG island, which is unmethylated both in cell lines and in primary lymphoma samples. CTCF binding, which was found in BCL6-expressing cell lines, correlated with the presence of histone variant H2A.Z and active histone marks, suggesting that CTCF induces chromatin modification at a transcriptionally active BCL6 locus. CTCF binding to exon1A was required to maintain BCL6 expression in germinal centre cells by avoiding BCL6-negative autoregulation. Silencing of CTCF in BCL6-expressing cells reduced BCL6 mRNA and protein expression, which is sufficient to induce B-cell terminal differentiation toward plasma cells. Moreover, lack of CTCF binding to exon1A shifts the BCL6 local chromatin from an active to a repressive state. This work demonstrates that, in contexts in which BCL6 is expressed, CTCF binding to BCL6 exon1A associates with epigenetic modifications indicative of transcriptionally open chromatin.
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Affiliation(s)
- A Batlle-López
- 1] Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC) and Departamento de Biología Molecular, Universidad de Cantabria, CSIC, SODERCAN, Santander, Spain [2] Servicio de Hematología, Hospital U. Marqués de Valdecilla, and IFIMAV-FMV, Santander, Spain
| | - M G Cortiguera
- 1] Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC) and Departamento de Biología Molecular, Universidad de Cantabria, CSIC, SODERCAN, Santander, Spain [2] Servicio de Hematología, Hospital U. Marqués de Valdecilla, and IFIMAV-FMV, Santander, Spain
| | - M Rosa-Garrido
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC) and Departamento de Biología Molecular, Universidad de Cantabria, CSIC, SODERCAN, Santander, Spain
| | - R Blanco
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC) and Departamento de Biología Molecular, Universidad de Cantabria, CSIC, SODERCAN, Santander, Spain
| | - E del Cerro
- Servicio de Hematología, Hospital U. Marqués de Valdecilla, and IFIMAV-FMV, Santander, Spain
| | - V Torrano
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC) and Departamento de Biología Molecular, Universidad de Cantabria, CSIC, SODERCAN, Santander, Spain
| | - S D Wagner
- Department of Cancer Studies and Molecular Medicine and MRC Toxicology Unit, University of Leicester, Leicester, UK
| | - M D Delgado
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC) and Departamento de Biología Molecular, Universidad de Cantabria, CSIC, SODERCAN, Santander, Spain
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18
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Chang KH, Huang A, Han H, Jiang Y, Fang X, Song CZ, Padilla S, Wang H, Qu H, Stamatoyannopoulos J, Li Q, Papayannopoulou T. Transcriptional environment and chromatin architecture interplay dictates globin expression patterns of heterospecific hybrids derived from undifferentiated human embryonic stem cells or from their erythroid progeny. Exp Hematol 2013; 41:967-979.e6. [PMID: 23993951 PMCID: PMC3836866 DOI: 10.1016/j.exphem.2013.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 08/20/2013] [Indexed: 11/21/2022]
Abstract
To explore the response of β globin locus with established chromatin domains upon their exposure to new transcriptional environments, we transferred the chromatin-packaged β globin locus of undifferentiated human embryonic stem cells (hESCs) or hESC-derived erythroblasts into an adult transcriptional environment. Distinct globin expression patterns were observed. In hESC-derived erythroblasts where both ε and γ globin were active and marked by similar chromatin modifications, ε globin was immediately silenced upon transfer, whereas γ globin continued to be expressed for months, implying that different transcriptional environments were required for their continuing expression. Whereas β globin was silent both in hESCs and in hESC-derived erythroblasts, β globin was only activated upon transfer from hESCs, but not in the presence of dominant γ globin transferred from hESC-derived erythroblasts, confirming the competing nature of γ versus β globin expression. With time, however, silencing of γ globin occurred in the adult transcriptional environment with concurrent activation of β-globin, accompanied by a drastic change in the epigenetic landscape of γ and β globin gene regions without apparent changes in the transcriptional environment. This switching process could be manipulated by overexpression or downregulation of certain transcription factors. Our studies provide important insights into the interplay between the transcription environment and existing chromatin domains, and we offer an experimental system to study the time-dependent human globin switching.
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Affiliation(s)
- Kai-Hsin Chang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Andy Huang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Hemei Han
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Yi Jiang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Xiangdong Fang
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
- Laboratory of Disease Genomics and Individualized Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100029, China
| | - Chao-Zhong Song
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Steve Padilla
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Hao Wang
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Hongzhu Qu
- Laboratory of Disease Genomics and Individualized Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100029, China
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | | | - Qiliang Li
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Thalia Papayannopoulou
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
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Taylor GCA, Eskeland R, Hekimoglu-Balkan B, Pradeepa MM, Bickmore WA. H4K16 acetylation marks active genes and enhancers of embryonic stem cells, but does not alter chromatin compaction. Genome Res 2013; 23:2053-65. [PMID: 23990607 PMCID: PMC3847775 DOI: 10.1101/gr.155028.113] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Compared with histone H3, acetylation of H4 tails has not been well studied, especially in mammalian cells. Yet, H4K16 acetylation is of particular interest because of its ability to decompact nucleosomes in vitro and its involvement in dosage compensation in flies. Here we show that, surprisingly, loss of H4K16 acetylation does not alter higher-order chromatin compaction in vivo in mouse embryonic stem cells (ESCs). As well as peaks of acetylated H4K16 and KAT8 histone acetyltransferase at the transcription start sites of expressed genes, we report that acetylation of H4K16 is a new marker of active enhancers in ESCs and that some enhancers are marked by H3K4me1, KAT8, and H4K16ac, but not by acetylated H3K27 or EP300, suggesting that they are novel EP300 independent regulatory elements. Our data suggest a broad role for different histone acetylation marks and for different histone acetyltransferases in long-range gene regulation.
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Affiliation(s)
- Gillian C A Taylor
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine at University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
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20
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Watanabe A, Yamada Y, Yamanaka S. Epigenetic regulation in pluripotent stem cells: a key to breaking the epigenetic barrier. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120292. [PMID: 23166402 DOI: 10.1098/rstb.2012.0292] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The differentiation and reprogramming of cells are accompanied by drastic changes in the epigenetic profiles of cells. Waddington's classical model clearly describes how differentiating cells acquire their cell identity as the developmental potential of an individual cell population declines towards the terminally differentiated state. The recent discovery of induced pluripotent stem cells as well as of somatic cell nuclear transfer provided evidence that the process of differentiation can be reversed. The identity of somatic cells is strictly protected by an epigenetic barrier, and these cells acquire pluripotency by breaking the epigenetic barrier by reprogramming factors such as Oct3/4, Sox2, Klf4, Myc and LIN28. This review covers the current understanding of the spatio-temporal regulation of epigenetics in pluripotent and differentiated cells, and discusses how cells determine their identity and overcome the epigenetic barrier during the reprogramming process.
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Affiliation(s)
- Akira Watanabe
- Center for iPS Cell Research and Application, Kyoto University
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21
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G9a histone methyltransferase activity in retinal progenitors is essential for proper differentiation and survival of mouse retinal cells. J Neurosci 2013; 32:17658-70. [PMID: 23223288 DOI: 10.1523/jneurosci.1869-12.2012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In vertebrate retinal development, various transcription factors are known to execute essential activities in gene regulation. Although epigenetic modification is considered to play a pivotal role in retinal development, the exact in vivo role of epigenetic regulation is still poorly understood. We observed that G9a histone methyltransferase, which methylates histone H3 at lysine 9 (H3K9), is substantially expressed in the mouse retina throughout development. To address in vivo G9a function in the mouse retina, we ablated G9a in retinal progenitor cells by conditional gene knock-out (G9a Dkk3 CKO). The G9a Dkk3 CKO retina exhibited severe morphological defects, including photoreceptor rosette formation, a partial loss of the outer nuclear layer, elevated cell death, and persistent cell proliferation. Progenitor cell-related genes, including several cyclins, Hes1, Chx10, and Lhx2, are methylated on histone H3K9 in the wild-type retina, but they were defective in H3K9 methylation and improperly upregulated at late developmental stages in the G9a Dkk3 CKO retina. Notably, conditional depletion of G9a in postmitotic photoreceptor precursors (G9a Crx CKO) led to the development of an almost normal retina, indicating that G9a activity mainly in retinal progenitor cells, but not in photoreceptor precursors, is essential for normal terminal differentiation of and survival of the retina. Our results suggest that proper epigenetic marks in progenitor cells are important for subsequent appropriate terminal differentiation and survival of retinal cells by repressing progenitor cell-related genes in differentiating retinal cells.
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22
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Liebau S, Mahaddalkar PU, Kestler HA, Illing A, Seufferlein T, Kleger A. A Hierarchy in Reprogramming Capacity in Different Tissue Microenvironments: What We Know and What We Need to Know. Stem Cells Dev 2013; 22:695-706. [DOI: 10.1089/scd.2012.0461] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Affiliation(s)
- Stefan Liebau
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - Pallavi U. Mahaddalkar
- Department on Stem Cell Aging, Institute of Molecular Medicine and Max Planck Research Group, Ulm University, Ulm, Germany
| | - Hans A. Kestler
- Research Group of Bioinformatics and Systems Biology, Institute of Neural Information Processing, Ulm University, Ulm, Germany
| | - Anett Illing
- Department of Internal Medicine 1, Ulm University Hospital, Ulm, Germany
| | - Thomas Seufferlein
- Department of Internal Medicine 1, Ulm University Hospital, Ulm, Germany
| | - Alexander Kleger
- Department of Internal Medicine 1, Ulm University Hospital, Ulm, Germany
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23
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Histone modifications of lineage-specific genesin human embryonic stem cellsduring in vitro differentiation. Epigenomics 2012. [DOI: 10.1017/cbo9780511777271.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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24
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Butler JS, Koutelou E, Schibler AC, Dent SYR. Histone-modifying enzymes: regulators of developmental decisions and drivers of human disease. Epigenomics 2012; 4:163-77. [PMID: 22449188 DOI: 10.2217/epi.12.3] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Precise transcriptional networks drive the orchestration and execution of complex developmental processes. Transcription factors possessing sequence-specific DNA binding properties activate or repress target genes in a step-wise manner to control most cell lineage decisions. This regulation often requires the interaction between transcription factors and subunits of massive protein complexes that bear enzymatic activities towards histones. The functional coupling of transcription proteins and histone modifiers underscores the importance of transcriptional regulation through chromatin modification in developmental cell fate decisions and in disease pathogenesis.
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Affiliation(s)
- Jill S Butler
- Department of Molecular Carcinogenesis at The Virginia Harris Cockrell Cancer Research Center, University of Texas MD Anderson Cancer Center Science Park, PO Box 389, Smithville, TX 78957, USA
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25
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Abstract
Emerging evidence is shedding light on a large and complex network of epigenetic modifications at play in human stem cells. This “epigenetic landscape” governs the fine-tuning and precision of gene expression programs that define the molecular basis of stem cell pluripotency, differentiation and reprogramming. This review will focus on recent progress in our understanding of the processes that govern this landscape in stem cells, such as histone modification, DNA methylation, alterations of chromatin structure due to chromatin remodeling and non-coding RNA activity. Further investigation into stem cell epigenetics promises to provide novel advances in the diagnosis and treatment of a wide array of human diseases.
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Abstract
Pluripotent embryonic stem cells can give rise to almost all somatic cell types but this characteristic requires precise control of their gene expression patterns. The necessity of keeping the entire genome "poised" to enter into any of a number of developmental possibilities requires a unique and highly plastic chromatin organisation based around specific patterns of histone modifications although this state of affairs is normally short lived during embryonic development. By deriving embryonic stem cells from the early embryo, we can preserve the highly specialised genome organisation and this has permitted several detailed investigations into the molecular basis of pluripotency.
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Affiliation(s)
- Lyle Armstrong
- Institute of Genetic Medicine, Newcastle University, The International Centre for Life, Central Parkway, Newcastle upon Tyne, UK.
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27
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Wynder C, Stalker L, Doughty ML. Role of H3K4 demethylases in complex neurodevelopmental diseases. Epigenomics 2012; 2:407-18. [PMID: 22121901 DOI: 10.2217/epi.10.12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Significant neurological disorders can result from subtle perturbations of gene regulation that are often linked to epigenetic regulation. Proteins that regulate the methylation of lysine 4 of histone H3 (H3K4) and play a central role in epigenetic regulation, and mutations in genes encoding these enzymes have been identified in both autism and Rett syndrome. The H3K4 demethylases remove methyl groups from lysine 4 leading to loss of RNA polymerase binding and transcriptional repression. When these proteins are mutated, brain development is altered. Currently, little is known regarding how these gene regulators function at the genomic level. In this article, we will discuss findings that link H3K4 demethylases to neurodevelopment and neurological disease.
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Affiliation(s)
- Christopher Wynder
- McMaster Stem Cell & Cancer Institute, McMaster University, Hamilton, Ontario L8N 3Z5 Canada.
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28
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Dillon N. Factor mediated gene priming in pluripotent stem cells sets the stage for lineage specification. Bioessays 2012; 34:194-204. [DOI: 10.1002/bies.201100137] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Schneider TD, Arteaga-Salas JM, Mentele E, David R, Nicetto D, Imhof A, Rupp RAW. Stage-specific histone modification profiles reveal global transitions in the Xenopus embryonic epigenome. PLoS One 2011; 6:e22548. [PMID: 21814581 PMCID: PMC3142184 DOI: 10.1371/journal.pone.0022548] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 06/29/2011] [Indexed: 02/03/2023] Open
Abstract
Vertebrate embryos are derived from a transitory pool of pluripotent cells. By the process of embryonic induction, these precursor cells are assigned to specific fates and differentiation programs. Histone post-translational modifications are thought to play a key role in the establishment and maintenance of stable gene expression patterns underlying these processes. While on gene level histone modifications are known to change during differentiation, very little is known about the quantitative fluctuations in bulk histone modifications during development. To investigate this issue we analysed histones isolated from four different developmental stages of Xenopus laevis by mass spectrometry. In toto, we quantified 59 modification states on core histones H3 and H4 from blastula to tadpole stages. During this developmental period, we observed in general an increase in the unmodified states, and a shift from histone modifications associated with transcriptional activity to transcriptionally repressive histone marks. We also compared these naturally occurring patterns with the histone modifications of murine ES cells, detecting large differences in the methylation patterns of histone H3 lysines 27 and 36 between pluripotent ES cells and pluripotent cells from Xenopus blastulae. By combining all detected modification transitions we could cluster their patterns according to their embryonic origin, defining specific histone modification profiles (HMPs) for each developmental stage. To our knowledge, this data set represents the first compendium of covalent histone modifications and their quantitative flux during normogenesis in a vertebrate model organism. The HMPs indicate a stepwise maturation of the embryonic epigenome, which may be causal to the progressing restriction of cellular potency during development.
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Affiliation(s)
- Tobias D Schneider
- Department of Molecular Biology, Adolf-Butenandt Institut, Ludwig-Maximilians-Universität München, Munich, Germany
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30
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Understanding the molecular circuitry of cell lineage specification in the early mouse embryo. Genes (Basel) 2011; 2:420-48. [PMID: 24710206 PMCID: PMC3927619 DOI: 10.3390/genes2030420] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 06/24/2011] [Accepted: 07/05/2011] [Indexed: 11/16/2022] Open
Abstract
Pluripotent stem cells hold great promise for cell-based therapies in regenerative medicine. However, critical to understanding and exploiting mechanisms of cell lineage specification, epigenetic reprogramming, and the optimal environment for maintaining and differentiating pluripotent stem cells is a fundamental knowledge of how these events occur in normal embryogenesis. The early mouse embryo has provided an excellent model to interrogate events crucial in cell lineage commitment and plasticity, as well as for embryo-derived lineage-specific stem cells and induced pluripotent stem (iPS) cells. Here we provide an overview of cell lineage specification in the early (preimplantation) mouse embryo focusing on the transcriptional circuitry and epigenetic marks necessary for successive differentiation events leading to the formation of the blastocyst.
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31
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Mahony S, Mazzoni EO, McCuine S, Young RA, Wichterle H, Gifford DK. Ligand-dependent dynamics of retinoic acid receptor binding during early neurogenesis. Genome Biol 2011; 12:R2. [PMID: 21232103 PMCID: PMC3091300 DOI: 10.1186/gb-2011-12-1-r2] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 12/10/2010] [Accepted: 01/13/2011] [Indexed: 01/31/2023] Open
Abstract
Background Among its many roles in development, retinoic acid determines the anterior-posterior identity of differentiating motor neurons by activating retinoic acid receptor (RAR)-mediated transcription. RAR is thought to bind the genome constitutively, and only induce transcription in the presence of the retinoid ligand. However, little is known about where RAR binds to the genome or how it selects target sites. Results We tested the constitutive RAR binding model using the retinoic acid-driven differentiation of mouse embryonic stem cells into differentiated motor neurons. We find that retinoic acid treatment results in widespread changes in RAR genomic binding, including novel binding to genes directly responsible for anterior-posterior specification, as well as the subsequent recruitment of the basal polymerase machinery. Finally, we discovered that the binding of transcription factors at the embryonic stem cell stage can accurately predict where in the genome RAR binds after initial differentiation. Conclusions We have characterized a ligand-dependent shift in RAR genomic occupancy at the initiation of neurogenesis. Our data also suggest that enhancers active in pluripotent embryonic stem cells may be preselecting regions that will be activated by RAR during neuronal differentiation.
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Affiliation(s)
- Shaun Mahony
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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32
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Kim H, Jang MJ, Kang MJ, Han YM. Epigenetic signatures and temporal expression of lineage-specific genes in hESCs during differentiation to hepatocytes in vitro. Hum Mol Genet 2010; 20:401-12. [DOI: 10.1093/hmg/ddq476] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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33
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Abstract
Stem cells of all types are characterized by a stable, heritable state permissive of multiple developmental pathways. The past five years have seen remarkable advances in understanding these heritable states and the ways that they are initiated or terminated. Transcription factors that bind directly to DNA and have sufficiency roles have been most easy to investigate and, perhaps for this reason, are most solidly implicated in pluripotency. In addition, large complexes of ATP-dependent chromatin-remodeling and histone-modification enzymes that have specialized functions have also been implicated by genetic studies in initiating and/or maintaining pluripotency or multipotency. Several of these ATP-dependent remodeling complexes play non-redundant roles, and the esBAF complex facilitates reprogramming of induced pluripotent stem cells. The recent finding that virtually all histone modifications can be rapidly reversed and are often highly dynamic has raised new questions about how histone modifications come to play a role in the steady state of pluripotency. Another surprise from genetic studies has been the frequency with which the global effects of mutations in chromatin regulators can be largely reversed by a single target gene. These genetic studies help define the arena for future mechanistic studies that might be helpful to harness pluripotency for therapeutic goals.
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Affiliation(s)
- Julie A Lessard
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal H3C 3J7, Quebec, Canada.
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34
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Liber D, Domaschenz R, Holmqvist PH, Mazzarella L, Georgiou A, Leleu M, Fisher AG, Labosky PA, Dillon N. Epigenetic priming of a pre-B cell-specific enhancer through binding of Sox2 and Foxd3 at the ESC stage. Cell Stem Cell 2010; 7:114-26. [PMID: 20621055 DOI: 10.1016/j.stem.2010.05.020] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 04/14/2010] [Accepted: 05/24/2010] [Indexed: 11/18/2022]
Abstract
Modifications to the core histones are thought to contribute to ESC pluripotency by priming tissue-specific promoters and enhancers for later activation. However, it is unclear how these marks are targeted in ESCs and maintained during differentiation. Here, we show that the ESC factor Sox2 targets H3K4 methylation to monovalent and bivalent domains. In ESCs, Sox2 contributes to the formation of a monovalent mark at an enhancer in the pro/pre-B cell-specific lambda5-VpreB1 locus. Binding of Foxd3 suppresses intergenic transcription of the enhancer and surrounding sequences. In pro-B cells, enhancer activity is dependent on the Sox and Fox binding sites, and the enhancer is bound by Sox4, which is required for efficient expression of lambda5. Our results lead us to propose a factor relay model whereby ESC factors establish active epigenetic marks at tissue specific elements before being replaced by cell type-specific factors as cells differentiate.
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Affiliation(s)
- Daniel Liber
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
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35
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Shahhoseini M, Taei A, Mehrjardi NZ, Salekdeh GH, Baharvand H. Epigenetic analysis of human embryonic carcinoma cells during retinoic acid-induced neural differentiation. Biochem Cell Biol 2010; 88:527-38. [PMID: 20555394 DOI: 10.1139/o09-181] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Differentiation of stem cells from a pluripotent to a committed state involves global changes in genome expression patterns, critically determined by chromatin structure and interactions of chromatin-binding proteins. The dynamics of chromatin structure are tightly regulated by multiple epigenetic mechanisms such as histone modifications and the incorporation of histone variants. In the current work, we induced neural differentiation of a human embryonal carcinoma stem cell line, NTERA2/NT2, by retinoic acid (RA) treatment, primarily according to two different methods of adherent cell culture (rosette formation) and suspension cell culture (EB formation) conditions, and histone modifications and variations were compared through these processes. Western blot analysis of histone extracts showed significant changes in the acetylation and methylation patterns of histone H3, and expression level of the histone variant H2A.Z, after RA treatment in both protocols. Using chromatin immunoprecipitation (ChIP) coupled with real-time PCR, it was shown that these epigenetic changes occurred on the regulatory regions of 4 marker genes (Oct4, Nanog, Nestin, and Pax6) in a culture condition dependent manner. This report demonstrates the dynamic interplay of histone modification and variation in regulating the gene expression profile, during stem cell differentiation and under different culture conditions.
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Affiliation(s)
- Maryam Shahhoseini
- Department of Genetics, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran.
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36
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Smale ST. Pioneer factors in embryonic stem cells and differentiation. Curr Opin Genet Dev 2010; 20:519-26. [PMID: 20638836 DOI: 10.1016/j.gde.2010.06.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Accepted: 06/22/2010] [Indexed: 01/12/2023]
Abstract
Most studies of tissue-specific and developmental stage-specific transcription have focused on the DNA motifs, transcription factors, or chromatin events required for the active transcription of a gene in cells in which the gene is expressed, or for its active or heritable silencing in nonexpressing cells. However, accumulating evidence suggests that, in multicellular eukaryotes, enhancers or promoters for tissue-specific genes interact with pioneer transcription factors in embryonic stem cells and at other early stages of development, long before the genes are transcribed. These early interactions, which can lead to the presence of unmethylated CpG dinucleotides, histone modification signatures, and/or chromatin remodeling, may carry out different functions at different classes of genes.
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Affiliation(s)
- Stephen T Smale
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095, USA.
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Kashyap V, Gudas LJ. Epigenetic regulatory mechanisms distinguish retinoic acid-mediated transcriptional responses in stem cells and fibroblasts. J Biol Chem 2010; 285:14534-48. [PMID: 20231276 DOI: 10.1074/jbc.m110.115345] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Retinoic acid (RA), a vitamin A metabolite, regulates transcription by binding to RA receptor (RAR) and retinoid X receptor (RXR) heterodimers. This transcriptional response is determined by receptor interactions with transcriptional regulators and chromatin modifying proteins. We compared transcriptional responses of three RA target genes (Hoxa1, Cyp26a1, RARbeta(2)) in primary embryo fibroblasts (mouse embryonic fibroblasts), immortalized fibroblasts (Balb/c3T3), and F9 teratocarcinoma stem cells. Hoxa1 and Cyp26a1 transcripts are not expressed, but RARbeta(2) transcripts are induced by RA in mouse embryonic fibroblasts and Balb/c3T3 cells. Retinoid receptors (RARgamma, RXRalpha), coactivators (pCIP (NCOA3, SRC3)), and p300 and RNA polymerase II are recruited only to the RARbeta(2) RA response element (RARE) in Balb/c3T3, whereas these proteins are recruited to RAREs of all three genes by RA in F9 cells. In F9, RA reduces polycomb (PcG) protein Suz12 and the associated H3K27me3 repressive epigenetic modification at the RAREs of all three genes. In contrast, in Balb/c3T3 cells cultured in the +/-RA, Suz12 is not associated with the Hoxa1, RARbeta(2), and Cyp26a1 RAREs, whereas slow levels of the H3K27me3 mark are seen at these RAREs. Thus, Suz12 is not required for gene repression in the absence of RA. Even though the Hoxa1 RARE and proximal promoter show high levels of H3K9,K14 acetylation in Balb/c3T3, the Hoxa1 gene is not transcriptionally activated by RA. In Balb/c3T3, CpG islands are methylated in the Cyp26a1 promoter region but not in the Hoxa1 promoter or in these promoters in F9 cells. We have delineated the complex mechanisms that control RA-mediated transcription in fibroblasts versus stem cells.
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Affiliation(s)
- Vasundhra Kashyap
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York 10065, USA
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Xu J, Watts JA, Pope SD, Gadue P, Kamps M, Plath K, Zaret KS, Smale ST. Transcriptional competence and the active marking of tissue-specific enhancers by defined transcription factors in embryonic and induced pluripotent stem cells. Genes Dev 2009; 23:2824-38. [PMID: 20008934 DOI: 10.1101/gad.1861209] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We reported previously that well-characterized enhancers but not promoters for typical tissue-specific genes, including the classic Alb1 gene, contain unmethylated CpG dinucleotides and evidence of pioneer factor interactions in embryonic stem (ES) cells. These properties, which are distinct from the bivalent histone modification domains that characterize the promoters of genes involved in developmental decisions, raise the possibility that genes expressed only in differentiated cells may need to be marked at the pluripotent stage. Here, we demonstrate that the forkhead family member FoxD3 is essential for the unmethylated mark observed at the Alb1 enhancer in ES cells, with FoxA1 replacing FoxD3 following differentiation into endoderm. Up-regulation of FoxD3 and loss of CpG methylation at the Alb1 enhancer accompanied the reprogramming of mouse embryonic fibroblasts (MEFs) into induced pluripotent stem (iPS) cells. Studies of two genes expressed in specific hematopoietic lineages revealed that the establishment of enhancer marks in ES cells and iPS cells can be regulated both positively and negatively. Furthermore, the absence of a pre-established mark consistently resulted in resistance to transcriptional activation in the repressive chromatin environment that characterizes differentiated cells. These results support the hypothesis that pluripotency and successful reprogramming may be critically dependent on the marking of enhancers for many or all tissue-specific genes.
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Affiliation(s)
- Jian Xu
- Molecular Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California at Los Angeles, Los Angeles, California 90095, USA
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Rincón-Arano H, Guerrero G, Valdes-Quezada C, Recillas-Targa F. Chicken alpha-globin switching depends on autonomous silencing of the embryonic pi globin gene by epigenetics mechanisms. J Cell Biochem 2009; 108:675-87. [PMID: 19693775 DOI: 10.1002/jcb.22304] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Switching in hemoglobin gene expression is an informative paradigm for studying transcriptional regulation. Here we determined the patterns of chicken alpha-globin gene expression during development and erythroid differentiation. Previously published data suggested that the promoter regions of alpha-globin genes contain the complete information for proper developmental regulation. However, our data show a preferential trans-activation of the embryonic alpha-globin gene independent of the developmental or differentiation stage. We also found that DNA methylation and histone deacetylation play key roles in silencing the expression of the embryonic pi gene in definitive erythrocytes. However, drug-mediated reactivation of the embryonic gene during definitive erythropoiesis dramatically impaired the expression of the adult genes, suggesting gene competition or interference for enhancer elements. Our results also support a model in which the lack of open chromatin marks and localized recruitment of chicken MeCP2 contribute to autonomous gene silencing of the embryonic alpha-globin gene in a developmentally specific manner. We propose that epigenetic mechanisms are necessary for in vivo chicken alpha-globin gene switching through differential gene silencing of the embryonic alpha-globin gene in order to allow proper activation of adult alpha-globin genes.
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Affiliation(s)
- Héctor Rincón-Arano
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, México 04510, DF, México
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40
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Epigenetic chromatin states uniquely define the developmental plasticity of murine hematopoietic stem cells. Blood 2009; 115:247-56. [PMID: 19887676 DOI: 10.1182/blood-2009-07-235176] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Heritable epigenetic signatures are proposed to serve as an important regulatory mechanism in lineage fate determination. To investigate this, we profiled chromatin modifications in murine hematopoietic stem cells, lineage-restricted progenitors, and CD4(+) T cells using modified genome-scale mini-chromatin immunoprecipitation technology. We show that genes involved in mature hematopoietic cell function associate with distinct chromatin states in stem and progenitor cells, before their activation or silencing upon cellular maturation. Many lineage-restricted promoters are associated with bivalent histone methylation and highly combinatorial histone modification patterns, which may determine their selective priming of gene expression during lineage commitment. These bivalent chromatin states are conserved in mammalian evolution, with a particular overrepresentation of promoters encoding key regulators of hematopoiesis. After differentiation into progenitors and T cells, activating histone modifications persist at transcriptionally repressed promoters, suggesting that these transcriptional programs might be reactivated after lineage restriction. Collectively, our data reveal the epigenetic framework that underlies the cell fate options of hematopoietic stem cells.
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Golebiewska A, Atkinson SP, Lako M, Armstrong L. Epigenetic landscaping during hESC differentiation to neural cells. Stem Cells 2009; 27:1298-308. [PMID: 19489095 DOI: 10.1002/stem.59] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The molecular mechanisms underlying pluripotency and lineage specification from embryonic stem cells (ESCs) are still largely unclear. To address the role of chromatin structure in maintenance of pluripotency in human ESCs (hESCs) and establishment of lineage commitment, we analyzed a panel of histone modifications at promoter sequences of genes involved in maintenance of pluripotency, self-renewal, and in early stages of differentiation. To understand the changes occurring at lineage-specific gene regulatory sequences, we have established an efficient purification system that permits the examination of two distinct populations of lineage committed cells; fluorescence activated cell sorted CD133(+) CD45(-)CD34(-) neural stem cells and beta-III-tubulin(+) putative neurons. Here we report the importance of other permissive marks supporting trimethylation of Lysine 4 H3 at the active stem cell promoters as well as poised bivalent and nonbivalent lineage-specific gene promoters in hESCs. Methylation of lysine 9 H3 was found to play a role in repression of pluripotency-associated and lineage-specific genes on differentiation. Moreover, presence of newly formed bivalent domains was observed at the neural progenitor stage. However, they differ significantly from the bivalent domains observed in hESCs, with a possible role of dimethylation of lysine 9 H3 in repressing the poised genes.
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Affiliation(s)
- Anna Golebiewska
- Institute of Human Genetics, University of Newcastle Upon Tyne, International Centre for Life, United Kingdom
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42
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Hippocampal development and neural stem cell maintenance require Sox2-dependent regulation of Shh. Nat Neurosci 2009; 12:1248-56. [PMID: 19734891 DOI: 10.1038/nn.2397] [Citation(s) in RCA: 380] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 08/05/2009] [Indexed: 12/15/2022]
Abstract
Neural stem cells (NSCs) are controlled by diffusible factors. The transcription factor Sox2 is expressed by NSCs and Sox2 mutations in humans cause defects in the brain and, in particular, in the hippocampus. We deleted Sox2 in the mouse embryonic brain. At birth, the mice showed minor brain defects; shortly afterwards, however, NSCs and neurogenesis were completely lost in the hippocampus, leading to dentate gyrus hypoplasia. Deletion of Sox2 in adult mice also caused hippocampal neurogenesis loss. The hippocampal developmental defect resembles that caused by late sonic hedgehog (Shh) loss. In mutant mice, Shh and Wnt3a were absent from the hippocampal primordium. A SHH pharmacological agonist partially rescued the hippocampal defect. Chromatin immunoprecipitation identified Shh as a Sox2 target. Sox2-deleted NSCs did not express Shh in vitro and were rapidly lost. Their replication was partially rescued by the addition of SHH and was almost fully rescued by conditioned medium from normal cells. Thus, NSCs control their status, at least partly, through Sox2-dependent autocrine mechanisms.
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43
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Histone hyperacetylation within the beta-globin locus is context-dependent and precedes high-level gene expression. Blood 2009; 114:3479-88. [PMID: 19690338 DOI: 10.1182/blood-2009-03-210690] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Active gene promoters are associated with covalent histone modifications, such as hyperacetylation, which can modulate chromatin structure and stabilize binding of transcription factors that recognize these modifications. At the beta-globin locus and several other loci, however, histone hyperacetylation extends beyond the promoter, over tens of kilobases; we term such patterns of histone modifications "hyperacetylated domains." Little is known of either the mechanism by which these domains form or their function. Here, we show that domain formation within the murine beta-globin locus occurs before either high-level gene expression or erythroid commitment. Analysis of beta-globin alleles harboring deletions of promoters or the locus control region demonstrates that these sequences are not required for domain formation, suggesting the existence of additional regulatory sequences within the locus. Deletion of embryonic globin gene promoters, however, resulted in the formation of a hyperacetylated domain over these genes in definitive erythroid cells, where they are otherwise inactive. Finally, sequences within beta-globin domains exhibit hyperacetylation in a context-dependent manner, and domains are maintained when transcriptional elongation is inhibited. These data narrow the range of possible mechanisms by which hyperacetylated domains form.
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Beltrami AP, Cesselli D, Beltrami CA. Pluripotency rush! Molecular cues for pluripotency, genetic reprogramming of adult stem cells, and widely multipotent adult cells. Pharmacol Ther 2009; 124:23-30. [PMID: 19545589 DOI: 10.1016/j.pharmthera.2009.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 06/02/2009] [Indexed: 12/14/2022]
Abstract
In the last few years, pluripotent stem cells have been the objective of intense investigation efforts. These cells are of paramount therapeutic interest, since they could be utilized: as in vitro models of disease, for pharmaceutical screening purposes, and for the regeneration of damaged organs. Over the years, pluripotent cells have been cultured from teratomas, the inner cell mass, and primordial germ cells. Accumulating informations have partially decrypted the molecular machinery responsible for the maintenance of a very primitive state, permitting the reprogramming of differentiated cells. Although the debate is still open, an extreme excitement is arising from two strictly related possibilities: pluripotent cells could be obtained from adult tissues with minimal manipulations or very rare pluripotent cells could be identified in adult tissues. This intriguing option will trigger new researches aimed both at identifying the possible biological role of pluripotent adult stem cells and at exploiting their potential clinical use. The present review article will summarize current knowledge of the molecular cues for pluripotency but also discusses whether pluripotent stem cells could be obtained from adult tissues.
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Affiliation(s)
- Antonio Paolo Beltrami
- Interdepartmental Center for Regenerative Medicine (CIME), Department of Pathology, University of Udine, Italy.
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45
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The LIM homeobox transcription factor Lhx2 is required to specify the retina field and synergistically cooperates with Pax6 for Six6 trans-activation. Dev Biol 2009; 327:541-50. [DOI: 10.1016/j.ydbio.2008.12.022] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 12/12/2008] [Accepted: 12/12/2008] [Indexed: 11/23/2022]
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Lee ER, Murdoch FE, Fritsch MK. High Histone Acetylation and Decreased Polycomb Repressive Complex 2 Member Levels Regulate Gene Specific Transcriptional Changes During Early Embryonic Stem Cell Differentiation Induced by Retinoic Acid. Stem Cells 2009; 25:2191-9. [PMID: 17525233 DOI: 10.1634/stemcells.2007-0203] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Histone modifications play a crucial role during embryonic stem (ES) cell differentiation. During differentiation, binding of polycomb repressive complex 2 (PRC2), which mediates trimethylation of lysine 27 on histone H3 (K27me3), is lost on developmental genes that are transcriptionally induced. We observed a global decrease in K27me3 in as little as 3 days after differentiation of mouse ES cells induced by retinoic acid (RA) treatment. The global levels of the histone K27 methyltransferase EZH2 also decreased with RA treatment. A loss of EZH2 binding and K27me3 was observed locally on PRC2 target genes induced after 3 days of RA, including Nestin. In contrast, direct RA-responsive genes that are rapidly induced, such as Hoxa1, showed a loss of EZH2 binding and K27me3 after only a few hours of RA treatment. Following differentiation induced by leukemia inhibitor factor (LIF) withdrawal without RA, Hoxa1 was not transcriptionally activated. Small interfering RNA-mediated knockdown of EZH2 resulted in loss of K27me3 during LIF withdrawal, but the Hoxa1 gene remained transcriptionally silent after loss of this repressive mark. Induction of histone hyperacetylation overrode the repressive K27me3 modification and resulted in Hoxa1 gene expression. Together, these data show that there are multiple temporal phases of derepression of PRC2 target genes during ES cell differentiation and that other epigenetic marks (specifically, increased acetylation of histones H3 and H4), in addition to derepression, are important for gene-specific transcriptional activation. This report demonstrates the temporal interplay of various epigenetic changes in regulating gene expression during early ES cell differentiation.
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Affiliation(s)
- Elliot R Lee
- Cancer Biology Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Karnowski A, Cao C, Matthias G, Carotta S, Corcoran LM, Martensson IL, Skok JA, Matthias P. Silencing and nuclear repositioning of the lambda5 gene locus at the pre-B cell stage requires Aiolos and OBF-1. PLoS One 2008; 3:e3568. [PMID: 18974788 PMCID: PMC2571989 DOI: 10.1371/journal.pone.0003568] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 09/15/2008] [Indexed: 12/30/2022] Open
Abstract
The chromatin regulator Aiolos and the transcriptional coactivator OBF-1 have been implicated in regulating aspects of B cell maturation and activation. Mice lacking either of these factors have a largely normal early B cell development. However, when both factors are eliminated simultaneously a block is uncovered at the transition between pre-B and immature B cells, indicating that these proteins exert a critical function in developing B lymphocytes. In mice deficient for Aiolos and OBF-1, the numbers of immature B cells are reduced, small pre-BII cells are increased and a significant impairment in immunoglobulin light chain DNA rearrangement is observed. We identified genes whose expression is deregulated in the pre-B cell compartment of these mice. In particular, we found that components of the pre-BCR, such as the surrogate light chain genes λ5 and VpreB, fail to be efficiently silenced in double-mutant mice. Strikingly, developmentally regulated nuclear repositioning of the λ5 gene is impaired in pre-B cells lacking OBF-1 and Aiolos. These studies uncover a novel role for OBF-1 and Aiolos in controlling the transcription and nuclear organization of genes involved in pre-BCR function.
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Affiliation(s)
- Alexander Karnowski
- Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Basel, Switzerland
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Chun Cao
- Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Basel, Switzerland
| | - Gabriele Matthias
- Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Basel, Switzerland
| | - Sebastian Carotta
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Lynn M. Corcoran
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Inga-Lill Martensson
- Laboratory of Lymphocyte Signaling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Jane A. Skok
- Department of Immunology and Molecular Pathology, University College London, London, United Kingdom
- New York University School of Medicine, New York, New York, United States of America
| | - Patrick Matthias
- Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Basel, Switzerland
- * E-mail:
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Stem cell–specific epigenetic priming and B cell–specific transcriptional activation at the mouse Cd19 locus. Blood 2008; 112:1673-82. [DOI: 10.1182/blood-2008-02-142786] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Low-level expression of multiple lineage-specific genes is a hallmark of hematopoietic stem cells (HSCs). HSCs predominantly express genes specific for the myeloid or megakaryocytic-erythroid lineages, whereas the transcription of lymphoid specific genes appears to begin after lymphoid specification. It has been demonstrated for a number of genes that epigenetic priming occurs before gene expression and lineage specification; however, little is known about how epigenetic priming of lymphoid genes is regulated. To address the question of how B cell–restricted expression is established, we studied activation of the Cd19 gene during hematopoietic development. We identified a B cell–specific upstream enhancer and showed that the developmental regulation of Cd19 expression involves precisely coordinated alterations in transcription factor binding and chromatin remodeling at Cd19 cis-regulatory elements. In multipotent progenitor cells, Cd19 chromatin is first remodeled at the upstream enhancer, and this remodeling is associated with binding of E2A. This is followed by the binding of EBF and PAX5 during B-cell differentiation. The Cd19 promoter is transcriptionally activated only after PAX5 binding. Our experiments give important mechanistic insights into how widely expressed and B lineage–specific transcription factors cooperate to mediate the developmental regulation of lymphoid genes during hematopoiesis.
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Garcia BA, Thomas CE, Kelleher NL, Mizzen CA. Tissue-specific expression and post-translational modification of histone H3 variants. J Proteome Res 2008; 7:4225-36. [PMID: 18700791 DOI: 10.1021/pr800044q] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Analyses of histone H3 from 10 rat tissues using a Middle Down proteomics platform revealed tissue-specific differences in their expression and global PTM abundance. ESI/FTMS with electron capture dissociation showed that, in general, these proteins were hypomodified in heart, liver and testes. H3.3 was hypermodified compared to H3.2 in some, but not all tissues. In addition, a novel rat testes-specific H3 protein was identified with this approach.
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Affiliation(s)
- Benjamin A Garcia
- Institute for Genomic Biology, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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50
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Abstract
Stem cell-based regenerative medicine holds great promise for repair of diseased tissue. Modern directions in the field of epigenetic research aimed to decipher the epigenetic signals that give stem cells their unique ability to self-renew and differentiate into different cell types. However, this research is only the tip of the iceberg when it comes to writing an 'epigenetic instruction manual' for the ramification of molecular details of cell commitment and differentiation. In this review, we discuss the impact of the epigenetic research on our understanding of stem cell biology.
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Affiliation(s)
- Victoria V Lunyak
- Buck Institute for Age Research, 8001 Redwood Blvd, Novato, CA 94945, USA.
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