151
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Cambuli F, Murray A, Dean W, Dudzinska D, Krueger F, Andrews S, Senner CE, Cook SJ, Hemberger M. Epigenetic memory of the first cell fate decision prevents complete ES cell reprogramming into trophoblast. Nat Commun 2014; 5:5538. [PMID: 25423963 PMCID: PMC4263130 DOI: 10.1038/ncomms6538] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 10/10/2014] [Indexed: 12/17/2022] Open
Abstract
Embryonic (ES) and trophoblast (TS) stem cells reflect the first, irrevocable cell fate decision in development that is reinforced by distinct epigenetic lineage barriers. Nonetheless, ES cells can seemingly acquire TS-like characteristics upon manipulation of lineage-determining transcription factors or activation of the extracellular signal-regulated kinase 1/2 (Erk1/2) pathway. Here we have interrogated the progression of reprogramming in ES cell models with regulatable Oct4 and Cdx2 transgenes or conditional Erk1/2 activation. Although trans-differentiation into TS-like cells is initiated, lineage conversion remains incomplete in all models, underpinned by the failure to demethylate a small group of TS cell genes. Forced expression of these non-reprogrammed genes improves trans-differentiation efficiency, but still fails to confer a stable TS cell phenotype. Thus, even ES cells in ground-state pluripotency cannot fully overcome the boundaries that separate the first cell lineages but retain an epigenetic memory of their ES cell origin.
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Affiliation(s)
- Francesco Cambuli
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
- Centre for Trophoblast Research, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - Alexander Murray
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
- Centre for Trophoblast Research, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - Wendy Dean
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Dominika Dudzinska
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
- Centre for Trophoblast Research, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - Felix Krueger
- Bioinformatics Group, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Simon Andrews
- Bioinformatics Group, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Claire E. Senner
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
- Centre for Trophoblast Research, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - Simon J. Cook
- Signalling Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Myriam Hemberger
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
- Centre for Trophoblast Research, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
- Wellcome Trust—Medical Research Council Cambridge Stem Cell Institute, Tennis Court Road, Cambridge CB2 1QR, UK
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152
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Abstract
Devising a cell culture method that maintains human pluripotent stem cells (PSCs) in a state similar to naive mouse embryonic stem cells (ESCs) has been a much sought after goal in recent years. Here I consider the historical background to this quest and ask why it is considered consequential.
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Affiliation(s)
- Martin F Pera
- University of Melbourne, Florey Institute of Neuroscience and Mental Health, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3010, Australia.
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153
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Zhang J, Liu G, Ruan Y, Wang J, Zhao K, Wan Y, Liu B, Zheng H, Peng T, Wu W, He P, Hu FQ, Jian R. Dax1 and Nanog act in parallel to stabilize mouse embryonic stem cells and induced pluripotency. Nat Commun 2014; 5:5042. [PMID: 25284313 PMCID: PMC4205889 DOI: 10.1038/ncomms6042] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 08/20/2014] [Indexed: 12/20/2022] Open
Abstract
Nanog expression is heterogeneous and dynamic in embryonic stem cells (ESCs). However, the mechanism for stabilizing pluripotency during the transitions between Nanog(high) and Nanog(low) states is not well understood. Here we report that Dax1 acts in parallel with Nanog to regulate mouse ESC (mESCs) identity. Dax1 stable knockdown mESCs are predisposed towards differentiation but do not lose pluripotency, whereas Dax1 overexpression supports LIF-independent self-renewal. Although partially complementary, Dax1 and Nanog function independently and cannot replace one another. They are both required for full reprogramming to induce pluripotency. Importantly, Dax1 is indispensable for self-renewal of Nanog(low) mESCs. Moreover, we report that Dax1 prevents extra-embryonic endoderm (ExEn) commitment by directly repressing Gata6 transcription. Dax1 may also mediate inhibition of trophectoderm differentiation independent or as a downstream effector of Oct4. These findings establish a basal role of Dax1 in maintaining pluripotency during the state transition of mESCs and somatic cell reprogramming.
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Affiliation(s)
- Junlei Zhang
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
| | - Gaoke Liu
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
| | - Yan Ruan
- Department of Pathogenic Biology, Third Military Medical University, Chongqing 400038, China
| | - Jiali Wang
- Department of Physiology, Third Military Medical University, Chongqing 400038, China
| | - Ke Zhao
- Laboratory of Oncology, Affiliated Hospital of Academy of Military Medical Sciences, Beijing 400038, China
| | - Ying Wan
- 1] Biomedical Analysis Center, Third Military Medical University, Chongqing 100071, China [2] Department of Immunology, Third Military Medical University, Chongqing 400038, China
| | - Bing Liu
- Laboratory of Oncology, Affiliated Hospital of Academy of Military Medical Sciences, Beijing 400038, China
| | - Hongting Zheng
- Department of Endocrinology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Tao Peng
- Research Center of Laboratory Medicine, Chengdu Military General Hospital, Sichuan 610083, China
| | - Wei Wu
- Department of Cardiothoracic Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Ping He
- Department of Cardiothoracic Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Fu-Quan Hu
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
| | - Rui Jian
- Department of Pathogenic Biology, Third Military Medical University, Chongqing 400038, China
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154
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Abranches E, Guedes AMV, Moravec M, Maamar H, Svoboda P, Raj A, Henrique D. Stochastic NANOG fluctuations allow mouse embryonic stem cells to explore pluripotency. Development 2014; 141:2770-9. [PMID: 25005472 DOI: 10.1242/dev.108910] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Heterogeneous expression of the transcription factor NANOG has been linked to the existence of various functional states in pluripotent stem cells. This heterogeneity seems to arise from fluctuations of Nanog expression in individual cells, but a thorough characterization of these fluctuations and their impact on the pluripotent state is still lacking. Here, we have used a novel fluorescent reporter to investigate the temporal dynamics of NANOG expression in mouse embryonic stem cells (mESCs), and to dissect the lineage potential of mESCs at different NANOG states. Our results show that stochastic NANOG fluctuations are widespread in mESCs, with essentially all expressing cells showing fluctuations in NANOG levels, even when cultured in ground-state conditions (2i media). We further show that fluctuations have similar kinetics when mESCs are cultured in standard conditions (serum plus leukemia inhibitory factor) or ground-state conditions, implying that NANOG fluctuations are inherent to the pluripotent state. We have then compared the developmental potential of low-NANOG and high-NANOG mESCs, grown in different conditions, and confirm that mESCs are more susceptible to enter differentiation at the low-NANOG state. Further analysis by gene expression profiling reveals that low-NANOG cells have marked expression of lineage-affiliated genes, with variable profiles according to the signalling environment. By contrast, high-NANOG cells show a more stable expression profile in different environments, with minimal expression of lineage markers. Altogether, our data support a model in which stochastic NANOG fluctuations provide opportunities for mESCs to explore multiple lineage options, modulating their probability to change functional state.
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Affiliation(s)
- Elsa Abranches
- Instituto de Medicina Molecular and Instituto de Histologia e Biologia do Desenvolvimento, Faculdade de Medicina da Universidade de Lisboa, Avenida Prof. Egas Moniz, Lisboa 1649-028, Portugal Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Avenida Brasilia - Doca de Pedrouços, Lisboa 1400-038, Portugal
| | - Ana M V Guedes
- Instituto de Medicina Molecular and Instituto de Histologia e Biologia do Desenvolvimento, Faculdade de Medicina da Universidade de Lisboa, Avenida Prof. Egas Moniz, Lisboa 1649-028, Portugal Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Avenida Brasilia - Doca de Pedrouços, Lisboa 1400-038, Portugal
| | - Martin Moravec
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Hedia Maamar
- Department of Bioengineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
| | - Petr Svoboda
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Arjun Raj
- Department of Bioengineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
| | - Domingos Henrique
- Instituto de Medicina Molecular and Instituto de Histologia e Biologia do Desenvolvimento, Faculdade de Medicina da Universidade de Lisboa, Avenida Prof. Egas Moniz, Lisboa 1649-028, Portugal Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Avenida Brasilia - Doca de Pedrouços, Lisboa 1400-038, Portugal
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155
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Abstract
Deciphering the mechanisms of epigenetic reprogramming provides fundamental insights into cell fate decisions, which in turn reveal strategies to make the reprogramming process increasingly efficient. Here we review recent advances in epigenetic reprogramming to pluripotency with a focus on the principal molecular regulators. We examine the trajectories connecting somatic and pluripotent cells, genetic and chemical methodologies for inducing pluripotency, the role of endogenous master transcription factors in establishing the pluripotent state, and functional interactions between reprogramming factors and epigenetic regulators. Defining the crosstalk among the diverse molecular actors implicated in cellular reprogramming presents a major challenge for future inquiry.
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Affiliation(s)
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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156
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Ueda J, Maehara K, Mashiko D, Ichinose T, Yao T, Hori M, Sato Y, Kimura H, Ohkawa Y, Yamagata K. Heterochromatin dynamics during the differentiation process revealed by the DNA methylation reporter mouse, MethylRO. Stem Cell Reports 2014; 2:910-24. [PMID: 24936475 PMCID: PMC4050349 DOI: 10.1016/j.stemcr.2014.05.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 05/08/2014] [Accepted: 05/10/2014] [Indexed: 12/21/2022] Open
Abstract
In mammals, DNA is methylated at CpG sites, which play pivotal roles in gene silencing and chromatin organization. Furthermore, DNA methylation undergoes dynamic changes during development, differentiation, and in pathological processes. The conventional methods represent snapshots; therefore, the dynamics of this marker within living organisms remains unclear. To track this dynamics, we made a knockin mouse that expresses a red fluorescent protein (RFP)-fused methyl-CpG-binding domain (MBD) protein from the ROSA26 locus ubiquitously; we named it MethylRO (methylation probe in ROSA26 locus). Using this mouse, we performed RFP-mediated methylated DNA immunoprecipitation sequencing (MeDIP-seq), whole-body section analysis, and live-cell imaging. We discovered that mobility and pattern of heterochromatin as well as DNA methylation signal intensity inside the nuclei can be markers for cellular differentiation status. Thus, the MethylRO mouse represents a powerful bioresource and technique for DNA methylation dynamics studies in developmental biology, stem cell biology, as well as in disease states. Changes in DNA methylation are tracked in living mice Heterochromatin structure changes dynamically during development and differentiation Heterochromatin of preimplantation embryonic cells is highly dynamic than ESCs Heterochromatin pattern in nucleus can be a marker for cell differentiation states
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Affiliation(s)
- Jun Ueda
- Center for Genetic Analysis of Biological Responses, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita 565-0871, Japan
| | - Kazumitsu Maehara
- Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan
| | - Daisuke Mashiko
- Graduate School of Medicine, Osaka University, Suita 565-0871, Japan
| | - Takako Ichinose
- Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan
| | - Tatsuma Yao
- Research and Development Center, Fuso Pharmaceutical Industries, Ltd., Osaka 536-8523, Japan
| | - Mayuko Hori
- Center for Genetic Analysis of Biological Responses, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita 565-0871, Japan
| | - Yuko Sato
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Hiroshi Kimura
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Yasuyuki Ohkawa
- Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan
| | - Kazuo Yamagata
- Center for Genetic Analysis of Biological Responses, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita 565-0871, Japan
- Corresponding author
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157
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Abstract
In pluripotent stem cells, the interplay between signaling cues, epigenetic regulators and transcription factors orchestrates developmental potency. Flexibility in gene expression control is imparted by molecular changes to the nucleosomes, the building block of chromatin. Here, we review the current understanding of the role of chromatin as a plastic and integrative platform to direct gene expression changes in pluripotent stem cells, giving rise to distinct pluripotent states. We will further explore the concept of epigenetic asymmetry, focusing primarily on histone stoichiometry and their associated modifications, that is apparent at both the nucleosome and chromosome-wide levels, and discuss the emerging importance of these asymmetric chromatin configurations in diversifying epigenetic states and their implications for cell fate control.
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Affiliation(s)
- Wee-Wei Tee
- Howard Hughes Medical Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Danny Reinberg
- Howard Hughes Medical Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
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158
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Torres-Padilla ME, Chambers I. Transcription factor heterogeneity in pluripotent stem cells: a stochastic advantage. Development 2014; 141:2173-81. [PMID: 24866112 DOI: 10.1242/dev.102624] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
When pluripotent cells are exposed to a uniform culture environment they routinely display heterogeneous gene expression. Aspects of this heterogeneity, such as Nanog expression, are linked to differences in the propensity of individual cells to either self-renew or commit towards differentiation. Recent findings have provided new insight into the underlying causes of this heterogeneity, which we summarise here using Nanog, a key regulator of pluripotency, as a model gene. We discuss the role of transcription factor heterogeneity in facilitating the intrinsically dynamic and stochastic nature of the pluripotency network, which in turn provides a potential benefit to a population of cells that needs to balance cell fate decisions.
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Affiliation(s)
- Maria-Elena Torres-Padilla
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM U964, Université de Strasbourg, Cité Universitaire de Strasbourg, Illkirch F-67404, France
| | - Ian Chambers
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
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159
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Condic ML. Totipotency: what it is and what it is not. Stem Cells Dev 2014; 23:796-812. [PMID: 24368070 PMCID: PMC3991987 DOI: 10.1089/scd.2013.0364] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 12/23/2013] [Indexed: 02/03/2023] Open
Abstract
There is surprising confusion surrounding the concept of biological totipotency, both within the scientific community and in society at large. Increasingly, ethical objections to scientific research have both practical and political implications. Ethical controversy surrounding an area of research can have a chilling effect on investors and industry, which in turn slows the development of novel medical therapies. In this context, clarifying precisely what is meant by "totipotency" and how it is experimentally determined will both avoid unnecessary controversy and potentially reduce inappropriate barriers to research. Here, the concept of totipotency is discussed, and the confusions surrounding this term in the scientific and nonscientific literature are considered. A new term, "plenipotent," is proposed to resolve this confusion. The requirement for specific, oocyte-derived cytoplasm as a component of totipotency is outlined. Finally, the implications of twinning for our understanding of totipotency are discussed.
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Affiliation(s)
- Maureen L Condic
- Department of Neurobiology, School of Medicine, University of Utah , Salt Lake City, Utah
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160
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Wen D, Saiz N, Rosenwaks Z, Hadjantonakis AK, Rafii S. Completely ES cell-derived mice produced by tetraploid complementation using inner cell mass (ICM) deficient blastocysts. PLoS One 2014; 9:e94730. [PMID: 24733255 PMCID: PMC3986396 DOI: 10.1371/journal.pone.0094730] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 03/18/2014] [Indexed: 01/15/2023] Open
Abstract
Tetraploid complementation is often used to produce mice from embryonic stem cells (ESCs) by injection of diploid (2n) ESCs into tetraploid (4n) blastocysts (ESC-derived mice). This method has also been adapted to mouse cloning and the derivation of mice from induced pluripotent stem (iPS) cells. However, the underlying mechanism(s) of the tetraploid complementation remains largely unclear. Whether this approach can give rise to completely ES cell-derived mice is an open question, and has not yet been unambiguously proven. Here, we show that mouse tetraploid blastocysts can be classified into two groups, according to the presence or absence of an inner cell mass (ICM). We designate these as type a (presence of ICM at blastocyst stage) or type b (absence of ICM). ESC lines were readily derived from type a blastocysts, suggesting that these embryos retain a pluripotent epiblast compartment; whereas the type b blastocysts possessed very low potential to give rise to ESC lines, suggesting that they had lost the pluripotent epiblast. When the type a blastocysts were used for tetraploid complementation, some of the resulting mice were found to be 2n/4n chimeric; whereas when type b blastocysts were used as hosts, the resulting mice are all completely ES cell-derived, with the newborn pups displaying a high frequency of abdominal hernias. Our results demonstrate that completely ES cell-derived mice can be produced using ICM-deficient 4n blastocysts, and provide evidence that the exclusion of tetraploid cells from the fetus in 2n/4n chimeras can largely be attributed to the formation of ICM-deficient blastocysts.
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Affiliation(s)
- Duancheng Wen
- Ansary Stem Cell Institute and Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, United States of America
- Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (DW); (SR)
| | - Nestor Saiz
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
| | - Zev Rosenwaks
- Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, New York, United States of America
| | | | - Shahin Rafii
- Ansary Stem Cell Institute and Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (DW); (SR)
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161
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Transcription regulation and chromatin structure in the pluripotent ground state. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:129-37. [DOI: 10.1016/j.bbagrm.2013.09.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/06/2013] [Accepted: 09/07/2013] [Indexed: 01/19/2023]
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162
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163
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164
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Hackett JA, Dietmann S, Murakami K, Down TA, Leitch HG, Surani MA. Synergistic mechanisms of DNA demethylation during transition to ground-state pluripotency. Stem Cell Reports 2013; 1:518-31. [PMID: 24371807 PMCID: PMC3871394 DOI: 10.1016/j.stemcr.2013.11.010] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 11/25/2013] [Accepted: 11/25/2013] [Indexed: 11/16/2022] Open
Abstract
Pluripotent stem cells (PSCs) occupy a spectrum of reversible molecular states ranging from a naive ground-state in 2i, to metastable embryonic stem cells (ESCs) in serum, to lineage-primed epiblast stem cells (EpiSCs). To investigate the role of DNA methylation (5mC) across distinct pluripotent states, we mapped genome-wide 5mC and 5-hydroxymethycytosine (5hmC) in multiple PSCs. Ground-state ESCs exhibit an altered distribution of 5mC and 5hmC at regulatory elements and dramatically lower absolute levels relative to ESCs in serum. By contrast, EpiSCs exhibit increased promoter 5mC coupled with reduced 5hmC, which contributes to their developmental restriction. Switch to 2i triggers rapid onset of both the ground-state gene expression program and global DNA demethylation. Mechanistically, repression of de novo methylases by PRDM14 drives DNA demethylation at slow kinetics, whereas TET1/TET2-mediated 5hmC conversion enhances both the rate and extent of hypomethylation. These processes thus act synergistically during transition to ground-state pluripotency to promote a robust hypomethylated state.
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Affiliation(s)
- Jamie A Hackett
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK ; Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK ; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Sabine Dietmann
- Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK
| | - Kazuhiro Murakami
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK ; Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK ; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Thomas A Down
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
| | - Harry G Leitch
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK ; Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK
| | - M Azim Surani
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK ; Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK ; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
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165
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Abstract
The expression of E-Cadherin, a protein best known for its role in cell adhesion, regulates the onset of embryonic differentiation.
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Affiliation(s)
- Margarida Sancho
- Margarida Sancho is in the British Heart Foundation Centre for Research Excellence, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, London, United Kingdom
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166
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Chattwood A, Nagayama K, Bolourani P, Harkin L, Kamjoo M, Weeks G, Thompson CRL. Developmental lineage priming in Dictyostelium by heterogeneous Ras activation. eLife 2013; 2:e01067. [PMID: 24282234 PMCID: PMC3838634 DOI: 10.7554/elife.01067] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In cell culture, genetically identical cells often exhibit heterogeneous behavior, with only 'lineage primed' cells responding to differentiation inducing signals. It has recently been proposed that such heterogeneity exists during normal embryonic development to allow position independent patterning based on 'salt and pepper' differentiation and sorting out. However, the molecular basis of lineage priming and how it leads to reproducible cell type proportioning are poorly understood. To address this, we employed a novel forward genetic approach in the model organism Dictyostelium discoideum. These studies reveal that the Ras-GTPase regulator gefE is required for normal lineage priming and salt and pepper differentiation. This is because Ras-GTPase activity sets the intrinsic response threshold to lineage specific differentiation signals. Importantly, we show that although gefE expression is uniform, transcription of its target, rasD, is both heterogeneous and dynamic, thus providing a novel mechanism for heterogeneity generation and position-independent differentiation. DOI: http://dx.doi.org/10.7554/eLife.01067.001.
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Affiliation(s)
- Alex Chattwood
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
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167
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Abstract
Experiments on the social amoeba Dictyostelium discoideum show that the origins of lineage bias in this system lie in the nutritional history of individual cells. Clues to the molecular basis for this process suggest similar forces may be at work in early mammalian development.
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Affiliation(s)
- Sophie M Morgani
- Sophie M Morgani is in the Danish Stem Cell Center (DanStem), University of Copenhagen, Copenhagen, Denmark
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168
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Ishiuchi T, Torres-Padilla ME. Towards an understanding of the regulatory mechanisms of totipotency. Curr Opin Genet Dev 2013; 23:512-8. [DOI: 10.1016/j.gde.2013.06.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 06/26/2013] [Accepted: 06/26/2013] [Indexed: 10/26/2022]
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169
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Abstract
Within the adult organism, stem cells reside in defined anatomical microenvironments called niches. These architecturally diverse microenvironments serve to balance stem cell self-renewal and differentiation. Proper regulation of this balance is instrumental to tissue repair and homeostasis, and any imbalance can potentially lead to diseases such as cancer. Within each of these microenvironments, a myriad of chemical and physical stimuli interact in a complex (synergistic or antagonistic) manner to tightly regulate stem cell fate. The in vitro replication of these in vivo microenvironments will be necessary for the application of stem cells for disease modeling, drug discovery, and regenerative medicine purposes. However, traditional reductionist approaches have only led to the generation of cell culture methods that poorly recapitulate the in vivo microenvironment. To that end, novel engineering and systems biology approaches have allowed for the investigation of the biological and mechanical stimuli that govern stem cell fate. In this review, the application of these technologies for the dissection of stem cell microenvironments will be analyzed. Moreover, the use of these engineering approaches to construct in vitro stem cell microenvironments that precisely control stem cell fate and function will be reviewed. Finally, the emerging trend of using high-throughput, combinatorial methods for the stepwise engineering of stem cell microenvironments will be explored.
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Affiliation(s)
- David A Brafman
- Department of Cellular and Molecular Medicine, Stem Cell Program, University of California at San Diego, La Jolla, California
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