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Du P, Wu J. Hallmarks of totipotent and pluripotent stem cell states. Cell Stem Cell 2024; 31:312-333. [PMID: 38382531 PMCID: PMC10939785 DOI: 10.1016/j.stem.2024.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/18/2024] [Accepted: 01/26/2024] [Indexed: 02/23/2024]
Abstract
Though totipotency and pluripotency are transient during early embryogenesis, they establish the foundation for the development of all mammals. Studying these in vivo has been challenging due to limited access and ethical constraints, particularly in humans. Recent progress has led to diverse culture adaptations of epiblast cells in vitro in the form of totipotent and pluripotent stem cells, which not only deepen our understanding of embryonic development but also serve as invaluable resources for animal reproduction and regenerative medicine. This review delves into the hallmarks of totipotent and pluripotent stem cells, shedding light on their key molecular and functional features.
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Affiliation(s)
- Peng Du
- MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
| | - Jun Wu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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2
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Patrat C, Ouimette JF, Rougeulle C. X chromosome inactivation in human development. Development 2020; 147:147/1/dev183095. [PMID: 31900287 DOI: 10.1242/dev.183095] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
X chromosome inactivation (XCI) is a key developmental process taking place in female mammals to compensate for the imbalance in the dosage of X-chromosomal genes between sexes. It is a formidable example of concerted gene regulation and a paradigm for epigenetic processes. Although XCI has been substantially deciphered in the mouse model, how this process is initiated in humans has long remained unexplored. However, recent advances in the experimental capacity to access human embryonic-derived material and in the laws governing ethical considerations of human embryonic research have allowed us to enlighten this black box. Here, we will summarize the current knowledge of human XCI, mainly based on the analyses of embryos derived from in vitro fertilization and of pluripotent stem cells, and highlight any unanswered questions.
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Affiliation(s)
- Catherine Patrat
- Université de Paris, UMR 1016, Institut Cochin, 75014 Paris, France .,Service de Biologie de la Reproduction - CECOS, Paris Centre Hospital, APHP.centre, 75014 Paris, France
| | | | - Claire Rougeulle
- Université de Paris, Epigenetics and Cell Fate, CNRS, F-75013 Paris, France
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3
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Freel BA, Sheets JN, Francis KR. iPSC modeling of rare pediatric disorders. J Neurosci Methods 2019; 332:108533. [PMID: 31811832 DOI: 10.1016/j.jneumeth.2019.108533] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 11/25/2019] [Accepted: 11/27/2019] [Indexed: 12/20/2022]
Abstract
Discerning the underlying pathological mechanisms and the identification of therapeutic strategies to treat individuals affected with rare neurological diseases has proven challenging due to a host of factors. For instance, rare diseases affecting the nervous system are inherently lacking in appropriate patient sample availability compared to more common diseases, while animal models often do not accurately recapitulate specific disease phenotypes. These challenges impede research that may otherwise illuminate aspects of disease initiation and progression, leading to the ultimate identification of potential therapeutics. The establishment of induced pluripotent stem cells (iPSCs) as a human cellular model with defined genetics has provided the unique opportunity to study rare diseases within a controlled environment. iPSC models enable researchers to define mutational effects on specific cell types and signaling pathways within increasingly complex systems. Among rare diseases, pediatric diseases affecting neurodevelopment and neurological function highlight the critical need for iPSC-based disease modeling due to the inherent difficulty associated with collecting human neural tissue and the complexity of the mammalian nervous system. Rare neurodevelopmental disorders are therefore ideal candidates for utilization of iPSC-based in vitro studies. In this review, we address both the state of the iPSC field in the context of their utility and limitations for neurodevelopmental studies, as well as speculating about the future applications and unmet uses for iPSCs in rare diseases.
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Affiliation(s)
- Bethany A Freel
- Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD, USA
| | - Jordan N Sheets
- Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD, USA
| | - Kevin R Francis
- Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD, USA; Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, USA.
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Terryn J, Tricot T, Gajjar M, Verfaillie C. Recent advances in lineage differentiation from stem cells: hurdles and opportunities? F1000Res 2018; 7:220. [PMID: 29552337 PMCID: PMC5829467 DOI: 10.12688/f1000research.12596.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/19/2018] [Indexed: 12/14/2022] Open
Abstract
Pluripotent stem cells have the property of long-term self-renewal and the potential to give rise to descendants of the three germ layers and hence all mature cells in the human body. Therefore, they hold the promise of offering insight not only into human development but also for human disease modeling and regenerative medicine. However, the generation of mature differentiated cells that closely resemble their
in vivo counterparts remains challenging. Recent advances in single-cell transcriptomics and computational modeling of gene regulatory networks are revealing a better understanding of lineage commitment and are driving modern genome editing approaches. Additional modification of the chemical microenvironment, as well as the use of bioengineering tools to recreate the cellular, extracellular matrix, and physical characteristics of the niche wherein progenitors and mature cells reside, is now being used to further improve the maturation and functionality of stem cell progeny.
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Affiliation(s)
- Joke Terryn
- Department of Development and Regeneration, Stem Cell Institute Leuven, KU Leuven, Belgium
| | - Tine Tricot
- Department of Development and Regeneration, Stem Cell Institute Leuven, KU Leuven, Belgium
| | - Madhavsai Gajjar
- Department of Development and Regeneration, Stem Cell Institute Leuven, KU Leuven, Belgium
| | - Catherine Verfaillie
- Department of Development and Regeneration, Stem Cell Institute Leuven, KU Leuven, Belgium
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Geens M, Chuva De Sousa Lopes SM. X chromosome inactivation in human pluripotent stem cells as a model for human development: back to the drawing board? Hum Reprod Update 2018; 23:520-532. [PMID: 28582519 DOI: 10.1093/humupd/dmx015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 05/17/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Human pluripotent stem cells (hPSC), both embryonic and induced (hESC and hiPSC), are regarded as a valuable in vitro model for early human development. In order to fulfil this promise, it is important that these cells mimic as closely as possible the in vivo molecular events, both at the genetic and epigenetic level. One of the most important epigenetic events during early human development is X chromosome inactivation (XCI), the transcriptional silencing of one of the two X chromosomes in female cells. XCI is important for proper development and aberrant XCI has been linked to several pathologies. Recently, novel data obtained using high throughput single-cell technology during human preimplantation development have suggested that the XCI mechanism is substantially different from XCI in mouse. It has also been suggested that hPSC show higher complexity in XCI than the mouse. Here we compare the available recent data to understand whether XCI during human preimplantation can be properly recapitulated using hPSC. OBJECTIVE AND RATIONALE We will summarize what is known on the timing and mechanisms of XCI during human preimplantation development. We will compare this to the XCI patterns that are observed during hPSC derivation, culture and differentiation, and comment on the cause of the aberrant XCI patterns observed in hPSC. Finally, we will discuss the implications of the aberrant XCI patterns on the applicability of hPSC as an in vitro model for human development and as cell source for regenerative medicine. SEARCH METHODS Combinations of the following keywords were applied as search criteria in the PubMed database: X chromosome inactivation, preimplantation development, embryonic stem cells, induced pluripotent stem cells, primordial germ cells, differentiation. OUTCOMES Recent single-cell RNASeq data have shed new light on the XCI process during human preimplantation development. These indicate a gradual inactivation on both XX chromosomes, starting from Day 4 of development and followed by a random choice to inactivate one of them, instead of the mechanism in mice where imprinted XCI is followed by random XCI. We have put these new findings in perspective using previous data obtained in human (and mouse) embryos. In addition, there is an ongoing discussion whether or not hPSC lines show X chromosome reactivation upon derivation, mimicking the earliest embryonic cells, and the XCI states observed during culture of hPSC are highly variable. Recent studies have shown that hPSC rapidly progress to highly aberrant XCI patterns and that this process is probably driven by suboptimal culture conditions. Importantly, these aberrant XCI states seem to be inherited by the differentiated hPSC-progeny. WIDER IMPLICATIONS The aberrant XCI states (and epigenetic instability) observed in hPSC throw a shadow on their applicability as an in vitro model for development and disease modelling. Moreover, as the aberrant XCI states observed in hPSC seem to shift to a more malignant phenotype, this may also have important consequences for the safety aspect of using hPSC in the clinic.
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Affiliation(s)
- Mieke Geens
- Research Group Reproduction and Genetics, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Jette, Brussels, Belgium
| | - Susana M Chuva De Sousa Lopes
- Department of Anatomy and Embryology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.,Department of Reproductive Medicine, Ghent-Fertility and Stem Cell Team (G-FaST), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
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6
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Balachandar V, Dhivya V, Gomathi M, Mohanadevi S, Venkatesh B, Geetha B. A review of Rett syndrome (RTT) with induced pluripotent stem cells. Stem Cell Investig 2016; 3:52. [PMID: 27777941 DOI: 10.21037/sci.2016.09.05] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 09/08/2016] [Indexed: 11/06/2022]
Abstract
Human induced pluripotent stem cells (hiPSCs) are pluripotent stem cells generated from somatic cells by the introduction of a combination of pluripotency-associated genes such as OCT4, SOX2, along with either KLF4 and c-MYC or NANOG and LIN28 via retroviral or lentiviral vectors. Most importantly, hiPSCs are similar to human embryonic stem cells (hESCs) functionally as they are pluripotent and can potentially differentiate into any desired cell type when provided with the appropriate cues, but do not have the ethical issues surrounding hESCs. For these reasons, hiPSCs have huge potential in translational medicine such as disease modeling, drug screening, and cellular therapy. Indeed, patient-specific hiPSCs have been generated for a multitude of diseases, including many with a neurological basis, in which disease phenotypes have been recapitulated in vitro and proof-of-principle drug screening has been performed. As the techniques for generating hiPSCs are refined and these cells become a more widely used tool for understanding brain development, the insights they produce must be understood in the context of the greater complexity of the human genome and the human brain. Disease models using iPS from Rett syndrome (RTT) patient's fibroblasts have opened up a new avenue of drug discovery for therapeutic treatment of RTT. The analysis of X chromosome inactivation (XCI) upon differentiation of RTT-hiPSCs into neurons will be critical to conclusively demonstrate the isolation of pre-XCI RTT-hiPSCs in comparison to post-XCI RTT-hiPSCs. The current review projects on iPSC studies in RTT as well as XCI in hiPSC were it suggests for screening new potential therapeutic targets for RTT in future for the benefit of RTT patients. In conclusion, patient-specific drug screening might be feasible and would be particularly helpful in disorders where patients frequently have to try multiple drugs before finding a regimen that works.
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Affiliation(s)
- Vellingiri Balachandar
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
| | - Venkatesan Dhivya
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
| | - Mohan Gomathi
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
| | - Subramaniam Mohanadevi
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
| | - Balasubramanian Venkatesh
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
| | - Bharathi Geetha
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
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7
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Geens M, Seriola A, Barbé L, Santalo J, Veiga A, Dée K, Van Haute L, Sermon K, Spits C. Female human pluripotent stem cells rapidly lose X chromosome inactivation marks and progress to a skewed methylation pattern during culture. Mol Hum Reprod 2016; 22:285-98. [DOI: 10.1093/molehr/gaw004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 01/13/2016] [Indexed: 12/25/2022] Open
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Pasque V, Plath K. X chromosome reactivation in reprogramming and in development. Curr Opin Cell Biol 2015; 37:75-83. [PMID: 26540406 DOI: 10.1016/j.ceb.2015.10.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 10/12/2015] [Accepted: 10/14/2015] [Indexed: 11/29/2022]
Abstract
Dramatic epigenetic changes take place during mammalian differentiation from the naïve pluripotent state including the silencing of one of the two X chromosomes in female cells through X chromosome inactivation. Conversely, reprogramming of somatic cells to naive pluripotency is coupled to X chromosome reactivation (XCR). Recent studies in the mouse system have shed light on the mechanisms of XCR by uncovering the timing and steps of XCR during reprogramming to induced pluripotent stem cells (iPSCs), allowing the generation of testable hypotheses during embryogenesis. In contrast, analyses of the X chromosome in human iPSCs have revealed important differences between mouse and human reprogramming processes that can partially be explained by the establishment of distinct pluripotent states and impact disease modeling and the application of human pluripotent stem cells. Here, we review recent literature on XCR as a readout and determinant of reprogramming to pluripotency.
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Affiliation(s)
- Vincent Pasque
- Department of Biological Chemistry, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Kathrin Plath
- Department of Biological Chemistry, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA.
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9
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Aberrant patterns of X chromosome inactivation in a new line of human embryonic stem cells established in physiological oxygen concentrations. Stem Cell Rev Rep 2015; 10:472-9. [PMID: 24633531 DOI: 10.1007/s12015-014-9505-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
One of the differences between murine and human embryonic stem cells (ESCs) is the epigenetic state of the X chromosomes in female lines. Murine ESCs (mESCs) present two transcriptionally active Xs that will undergo the dosage compensation process of XCI upon differentiation, whereas most human ESCs (hESCs) spontaneously inactivate one X while keeping their pluripotency. Whether this reflects differences in embryonic development of mice and humans, or distinct culture requirements for the two kinds of pluripotent cells is not known. Recently it has been shown that hESCs established in physiological oxygen levels are in a stable pre-XCI state equivalent to that of mESCs, suggesting that culture in low oxygen concentration is enough to preserve that epigenetic state of the X chromosomes. Here we describe the establishment of two new lines of hESCs under physiological oxygen level and the characterization of the XCI state in the 46,XX line BR-5. We show that a fraction of undifferentiated cells present XIST RNA accumulation and single H3K27me foci, characteristic of the inactive X. Moreover, analysis of allele specific gene expression suggests that pluripotent BR-5 cells present completely skewed XCI. Our data indicate that physiological levels of oxygen are not sufficient for the stabilization of the pre-XCI state in hESCs.
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10
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Qi Q, Ding C, Hong P, Yang G, Xie Y, Wang J, Huang S, He K, Zhou C. X chromosome inactivation in human parthenogenetic embryonic stem cells following prolonged passaging. Int J Mol Med 2014; 35:569-78. [PMID: 25524499 PMCID: PMC4314418 DOI: 10.3892/ijmm.2014.2044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/01/2014] [Indexed: 11/28/2022] Open
Abstract
The present study aimed to investigate the X chrochromosome inactivation (XCI) status in long-term cultured human parthenogenetic embryonic stem cells. One human embryonic stem (hES) cell line and 2 human parthenogenetic embryonic stem (hPES) cell lines were subjected to long-term culture in vitro (>50 passages). Karyotyping, array-based comparative genomic hybridization (aCGH), X-inactive specific transcript (XIST) RNA, immunofluorescence staining and real-time PCR were used to assess the chromosome karyotypes of these cells and the XCI status. X chromosome microdeletion was observed in the hPES-2 cells following culture for 50 passages. As early as 20 passages, XIST RNA expression was detected in the hPES-2 cells and was followed by low X-linked gene expression. The XIST RNA expression level was higher in the differentiated hPES-2 cells. The hPES-2′ cells that were subclones of hPES-2 retained the XCI status, and had low XIST and X-linked gene expression. XIST RNA expression remained at a low level in the differentiated hPES-2′ cells. The human biparental embryonic stem (hBES)-1 and hPES-1 cells did not exhibit XCI, and the differentiated hPES-1 cells had high expression levels of XIST RNA. In conclusion, the chromosome karyotypes of some hPES cell lines revealed instabilities. Similar to the hES cells, the hPES cells exhibited 3 XCI statuses. The unstable XCI status of the hPES-2 line may have been related to chromosome instability. These unstable chromosomes renedered these cells susceptible to environmental conditions and freezing processes, which may be the result of environmental adaptations.
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Affiliation(s)
- Quan Qi
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Chenhui Ding
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Pingping Hong
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Gang Yang
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yanxin Xie
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Jing Wang
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Sunxing Huang
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Ke He
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Canquan Zhou
- Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
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High-resolution chromosomal microarray analysis of early-stage human embryonic stem cells reveals an association between X chromosome instability and skewed X inactivation. Cell Biosci 2014; 4:74. [PMID: 25506417 PMCID: PMC4265433 DOI: 10.1186/2045-3701-4-74] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 11/17/2014] [Indexed: 01/14/2023] Open
Abstract
X chromosome inactivation (XCI) is a dosage compensation mechanism that silences the majority of genes on one X chromosome in each female cell via a random process. Skewed XCI is relevant to many diseases, but the mechanism leading to it remains unclear. Human embryonic stem cells (hESCs) derived from the inner cell mass (ICM) of blastocyst-stage embryos have provided an excellent model system for understanding XCI initiation and maintenance. Here, we derived hESC lines with random or skewed XCI patterns from poor-quality embryos and investigated the genome-wide copy number variation (CNV) and loss of heterozygosity (LOH) patterns at the early passages of these two groups of hESC lines. It was found that the average size of CNVs on the X chromosomes in the skewed group is twice as much as that in the random group. Moreover, the LOH regions of the skewed group covered the gene locus of either XIST or XACT, which are master long non-coding RNA (lncRNA) effectors of XCI in human pluripotent stem cells. In conclusion, our work has established an experimentally tractable hESC model for study of skewed XCI and revealed an association between X chromosome instability and skewed XCI.
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12
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De Paepe C, Krivega M, Cauffman G, Geens M, Van de Velde H. Totipotency and lineage segregation in the human embryo. ACTA ACUST UNITED AC 2014; 20:599-618. [DOI: 10.1093/molehr/gau027] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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13
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Buckberry S, Bianco-Miotto T, Roberts CT. Imprinted and X-linked non-coding RNAs as potential regulators of human placental function. Epigenetics 2013; 9:81-9. [PMID: 24081302 DOI: 10.4161/epi.26197] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Pregnancy outcome is inextricably linked to placental development, which is strictly controlled temporally and spatially through mechanisms that are only partially understood. However, increasing evidence suggests non-coding RNAs (ncRNAs) direct and regulate a considerable number of biological processes and therefore may constitute a previously hidden layer of regulatory information in the placenta. Many ncRNAs, including both microRNAs and long non-coding transcripts, show almost exclusive or predominant expression in the placenta compared with other somatic tissues and display altered expression patterns in placentas from complicated pregnancies. In this review, we explore the results of recent genome-scale and single gene expression studies using human placental tissue, but include studies in the mouse where human data are lacking. Our review focuses on the ncRNAs epigenetically regulated through genomic imprinting or X-chromosome inactivation and includes recent evidence surrounding the H19 lincRNA, the imprinted C19MC cluster microRNAs, and X-linked miRNAs associated with pregnancy complications.
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Affiliation(s)
- Sam Buckberry
- The Robinson Institute; Research Centre for Reproductive Health; School of Paediatrics and Reproductive Health; The University of Adelaide; Adelaide, SA Australia
| | - Tina Bianco-Miotto
- The Robinson Institute; Research Centre for Reproductive Health; School of Paediatrics and Reproductive Health; The University of Adelaide; Adelaide, SA Australia; School of Agriculture Food & Wine; The University of Adelaide; Adelaide, SA Australia
| | - Claire T Roberts
- The Robinson Institute; Research Centre for Reproductive Health; School of Paediatrics and Reproductive Health; The University of Adelaide; Adelaide, SA Australia
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14
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Lessing D, Anguera MC, Lee JT. X chromosome inactivation and epigenetic responses to cellular reprogramming. Annu Rev Genomics Hum Genet 2013; 14:85-110. [PMID: 23662665 DOI: 10.1146/annurev-genom-091212-153530] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Reprogramming somatic cells to derive induced pluripotent stem cells (iPSCs) has provided a new method to model disease and holds great promise for regenerative medicine. Although genetically identical to their donor somatic cells, iPSCs undergo substantial changes in the epigenetic landscape during reprogramming. One such epigenetic process, X chromosome inactivation (XCI), has recently been shown to vary widely in human female iPSCs and embryonic stem cells (ESCs). XCI is a form of dosage compensation whose chief regulator is the noncoding RNA Xist. In mouse iPSCs and ESCs, Xist expression and XCI strictly correlate with the pluripotent state, but no such correlation exists in humans. Lack of XIST expression in human cells is linked to reduced developmental potential and an altered transcriptional profile, including upregulation of genes associated with cancer, which has therefore led to concerns about the safety of pluripotent stem cells for use in regenerative medicine. In this review, we describe how different states of XIST expression define three classes of female human pluripotent stem cells and explore progress in discovering the reasons for these variations and how they might be countered.
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Affiliation(s)
- Derek Lessing
- Howard Hughes Medical Institute, Department of Molecular Biology, and Department of Genetics, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114; , ,
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15
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Lee JT, Bartolomei MS. X-inactivation, imprinting, and long noncoding RNAs in health and disease. Cell 2013; 152:1308-23. [PMID: 23498939 DOI: 10.1016/j.cell.2013.02.016] [Citation(s) in RCA: 503] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Indexed: 12/22/2022]
Abstract
X chromosome inactivation and genomic imprinting are classic epigenetic processes that cause disease when not appropriately regulated in mammals. Whereas X chromosome inactivation evolved to solve the problem of gene dosage, the purpose of genomic imprinting remains controversial. Nevertheless, the two phenomena are united by allelic control of large gene clusters, such that only one copy of a gene is expressed in every cell. Allelic regulation poses significant challenges because it requires coordinated long-range control in cis and stable propagation over time. Long noncoding RNAs have emerged as a common theme, and their contributions to diseases of imprinting and the X chromosome have become apparent. Here, we review recent advances in basic biology, the connections to disease, and preview potential therapeutic strategies for future development.
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Affiliation(s)
- Jeannie T Lee
- Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA.
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16
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Nguyen HT, Geens M, Spits C. Genetic and epigenetic instability in human pluripotent stem cells. Hum Reprod Update 2012; 19:187-205. [PMID: 23223511 DOI: 10.1093/humupd/dms048] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND There is an increasing body of evidence that human pluripotent stem cells (hPSCs) are prone to (epi)genetic instability during in vitro culture. This review aims at giving a comprehensive overview of the current knowledge on culture-induced (epi)genetic alterations in hPSCs and their phenotypic consequences. METHODS Combinations of the following key words were applied as search criteria: human induced pluripotent stem cells and human embryonic stem cells in combination with malignancy, tumorigenicity, X inactivation, mitochondrial mutations, genomic integrity, chromosomal abnormalities, culture adaptation, aneuploidy and CD30. Only studies in English, on hPSCs and focused on (epi)genomic integrity were included. Further manuscripts were added from cross-references. RESULTS Numerous (epi)genetic aberrations have been detected in hPSCs. Recurrent genetic alterations give a selective advantage in culture to the altered cells leading to overgrowth of abnormal, culture-adapted cells. The functional effects of these alterations are not yet fully understood, but suggest a (pre)malignant transformation of abnormal cells with decreased differentiation and increased proliferative capacity. CONCLUSIONS Given the high degree of (epi)genetic alterations reported in the literature and altered phenotypic characteristics of the abnormal cells, controlling for the (epi)genetic integrity of hPSCs before any clinical application is an absolute necessity.
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Affiliation(s)
- H T Nguyen
- Research Group Reproduction and Genetics, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Jette, Brussels, Belgium
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Choi HW, Kim JS, Jang HJ, Choi S, Kim JH, Schöler HR, Do JT. Reestablishment of the inactive X chromosome to the ground state through cell fusion-induced reprogramming. Cell Mol Life Sci 2012; 69:4067-77. [PMID: 26250157 PMCID: PMC11114956 DOI: 10.1007/s00018-012-1139-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 08/13/2012] [Accepted: 08/13/2012] [Indexed: 12/31/2022]
Abstract
The restricted gene expression pattern of a differentiated cell can be reversed by fusion of the somatic cell with a more developmentally potent cell type, such as an embryonic stem (ES) cell. During this reprogramming process, somatic cells obtain most of the characteristics of pluripotent cells. Reactivation of an inactive X chromosome (Xi) is an important epigenetic marker confirming the pluripotent reprogramming of somatic cells. Female somatic cells contain one active X chromosome (Xa) and one Xi, and following the fusion of these cells with male ES cells, the Xi becomes activated, resulting in XaXaXaY fusion hybrid cells. To monitor Xi reactivation, transgenic female neural stem cells (fNSCs) carrying a green fluorescent protein (GFP) reporter gene expressed on the Xa (X-GFP), but not on the Xi, were used for reprogramming. XaXi(GFP) NSCs, whose GFP reporter was silenced, were fused with HM1 ES cells (XY) to induce pluripotent reprogramming. The Xi(GFP) of NSCs were found to be activated on day 4 post-fusion, indicating reactivation of the Xi. Hybrid cells showed pluripotent cell-specific characteristics cells including inactivation of the NSC marker Nestin, DNA demethylation of Oct4, DNA methylation of Nestin, and reactivation of the Xi. Following differentiation of the (GFP-positive) hybrid cells through embryoid body formation, the proportion of GFP-negative cells was found to be approximately 26 %, indicating that there was random inactivation of one of the three Xas. Here, we showed that the Xi of somatic cells is reprogrammed to the Xa state and that cellular differentiation occurs randomly, i.e., regardless of the Xa or Xi state, indicating that the memory of the Xi of somatic cells has been erased and reset to the ground state (i.e., inner cell mass-like state), indicating that random X-chromosome inactivation occurs upon differentiation.
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Affiliation(s)
- Hyun Woo Choi
- Department of Animal Biotechnology, College of Animal Bioscience and Technology, Konkuk University, Seoul, 143-701 Republic of Korea
- Department of Biomedical Science, CHA University, 605-21 Yoeksam 1-dong, Gangnam-gu, Seoul, 135-081 Republic of Korea
| | - Jong Soo Kim
- Department of Animal Biotechnology, College of Animal Bioscience and Technology, Konkuk University, Seoul, 143-701 Republic of Korea
| | - Hyo Jin Jang
- Department of Animal Biotechnology, College of Animal Bioscience and Technology, Konkuk University, Seoul, 143-701 Republic of Korea
- Department of Biomedical Science, CHA University, 605-21 Yoeksam 1-dong, Gangnam-gu, Seoul, 135-081 Republic of Korea
| | - Sol Choi
- Department of Animal Biotechnology, College of Animal Bioscience and Technology, Konkuk University, Seoul, 143-701 Republic of Korea
| | - Jae-Hwan Kim
- Department of Biomedical Science, CHA University, Pochan-si, Gyeonggi-do, Republic of Korea
| | - Hans R. Schöler
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149 Münster, Germany
| | - Jeong Tae Do
- Department of Animal Biotechnology, College of Animal Bioscience and Technology, Konkuk University, Seoul, 143-701 Republic of Korea
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18
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Epigenetic stability of human pluripotent stem cells. Epigenomics 2012. [DOI: 10.1017/cbo9780511777271.013] [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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19
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Bermejo-Alvarez P, Ramos-Ibeas P, Gutierrez-Adan A. Solving the "X" in embryos and stem cells. Stem Cells Dev 2012; 21:1215-24. [PMID: 22309156 DOI: 10.1089/scd.2011.0685] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
X-chromosome inactivation (XCI) is a complex epigenetic process that ensures that most X-linked genes are expressed equally for both sexes. Female eutherian mammals inactivate randomly the maternal or paternal inherited X-chromosome early in embryogenesis, whereas the extra-embryonic tissues experience an imprinting XCI that results in the inactivation of the paternal X-chromosome in mice. Although the phenomenon was initially described 40 years ago, many aspects remain obscure. In the last 2 years, some trademark publications have shed new light on the ongoing debate regarding the timing and mechanism of imprinted or random XCI. It has been observed that XCI is not accomplished at the blastocyst stage in bovines, rabbits, and humans, contrasting with the situation reported in mice, the standard model. All the species present 2 active X-chromosomes (Xa) in the early epiblast of the blastocyst, the cellular source for embryonic stem cells (ESCs). In this perspective, it would make sense to expect an absence of XCI in undifferentiated ESCs, but human ESCs are highly heterogeneous for this parameter and the presence of 2 Xa has been proposed as a true hallmark of ground-state pluripotency and a quality marker for female ESCs. Similarly, XCI reversal in female induced pluripotent stem cells is a key reprogramming event on the path to achieve the naïve pluripotency, and key pluripotency regulators can interact directly or indirectly with Xist. Finally, the presence of 2 Xa may lead to a sex-specific transcriptional regulation resulting in sexual dimorphism in reprogramming and differentiation.
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20
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Cheung AYL, Horvath LM, Carrel L, Ellis J. X-chromosome inactivation in rett syndrome human induced pluripotent stem cells. Front Psychiatry 2012; 3:24. [PMID: 22470355 PMCID: PMC3311266 DOI: 10.3389/fpsyt.2012.00024] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 03/05/2012] [Indexed: 12/20/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder that affects girls due primarily to heterozygous mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MECP2). Random X-chromosome inactivation (XCI) results in cellular mosaicism in which some cells express wild-type (WT) MECP2 while other cells express mutant MECP2. The generation of patient-specific human induced pluripotent stem cells (hiPSCs) facilitates the production of RTT-hiPSC-derived neurons in vitro to investigate disease mechanisms and identify novel drug treatments. The generation of RTT-hiPSCs has been reported by many laboratories, however, the XCI status of RTT-hiPSCs has been inconsistent. Some report RTT-hiPSCs retain the inactive X-chromosome (post-XCI) of the founder somatic cell allowing isogenic RTT-hiPSCs that express only the WT or mutant MECP2 allele to be isolated from the same patient. Post-XCI RTT-hiPSCs-derived neurons retain this allele-specific expression pattern of WT or mutant MECP2. Conversely, others report RTT-hiPSCs in which the inactive X-chromosome of the founder somatic cell reactivates (pre-XCI) upon reprogramming into RTT-hiPSCs. Pre-XCI RTT-hiPSC-derived neurons exhibit random XCI resulting in cellular mosaicism with respect to WT and mutant MECP2 expression. Here we review and attempt to interpret the inconsistencies in XCI status of RTT-hiPSCs generated to date by comparison to other pluripotent systems in vitro and in vivo and the methods used to analyze XCI. Finally, we discuss the relative strengths and weaknesses of post- and pre-XCI hiPSCs in the context of RTT, and other X-linked and autosomal disorders for translational medicine.
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Affiliation(s)
- Aaron Y L Cheung
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children Toronto, ON, Canada
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21
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Fan G, Tran J. X chromosome inactivation in human and mouse pluripotent stem cells. Hum Genet 2011; 130:217-22. [PMID: 21678064 DOI: 10.1007/s00439-011-1038-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 06/07/2011] [Indexed: 10/18/2022]
Abstract
Since the groundbreaking hypothesis of X chromosome inactivation (XCI) proposed by Mary Lyon over 50 years ago, a great amount of knowledge has been gained regarding this essential dosage compensation mechanism in female cells. For the mammalian system, most of the mechanistic studies of XCI have so far been investigated in the mouse model system, but recently, a number of interesting XCI studies have been extended to human pluripotent stem cells, including both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Emerging data indicate that XCI in hESCs and hiPSCs is much more complicated than that of their mouse counterparts. XCI in human pluripotent stem cells is not as stable and is subject to environmental influences and epigenetic regulation in vitro. This mini-review highlights the key differences in XCI between mouse and human stem cells with a greater emphasis placed on the understanding of the epigenetic regulation of XCI in human stem cells.
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Affiliation(s)
- Guoping Fan
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, 695 Charles Young Drive South, Los Angeles, CA 90095, USA.
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22
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XCI in preimplantation mouse and human embryos: first there is remodelling…. Hum Genet 2011; 130:203-15. [PMID: 21647603 PMCID: PMC3132436 DOI: 10.1007/s00439-011-1014-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 05/19/2011] [Indexed: 12/21/2022]
Abstract
Female eutherians silence one of their X chromosomes to accomplish an equal dose of X-linked gene expression compared with males. The mouse is the most widely used animal model in XCI research and has proven to be of great significance for understanding the complex mechanism of X-linked dosage compensation. Although the basic principles of XCI are similar in mouse and humans, differences exist in the timing of XCI initiation, the genetic elements involved in XCI regulation and the form of XCI in specific tissues. Therefore, the mouse has its limitations as a model to understand early human XCI and analysis of human tissues is required. In this review, we describe these differences with respect to initiation of XCI in human and mouse preimplantation embryos, the extra-embryonic tissues and the in vitro model of the epiblast: the embryonic stem cells.
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23
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Makhlouf M, Rougeulle C. Linking X chromosome inactivation to pluripotency: Necessity or fate? Trends Mol Med 2011; 17:329-36. [PMID: 21411371 DOI: 10.1016/j.molmed.2011.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 02/04/2011] [Accepted: 02/07/2011] [Indexed: 01/19/2023]
Abstract
Silencing one X chromosome is essential for the development of female mammals, but the regulation of this process appears to vary between species. In the mouse, which has thus far been the leading model system in the field, X chromosome inactivation (XCI) is tightly coupled to pluripotency and the underlying mechanisms have just begun to be deciphered. However, mechanistic aspects of XCI regulation in other species have yet to be thoroughly investigated. Here we review current knowledge of the developmental regulation of XCI in mice and humans and discuss the extent to which the intimate link between XCI and pluripotency extends beyond rodents.
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Affiliation(s)
- Mélanie Makhlouf
- UMR7216 Epigenetics and Cell Fate, CNRS/Université Paris Diderot, 35 rue Hélène Brion, 75013 Paris, France
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24
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Bruck T, Benvenisty N. Meta-analysis of the heterogeneity of X chromosome inactivation in human pluripotent stem cells. Stem Cell Res 2010; 6:187-93. [PMID: 21276761 DOI: 10.1016/j.scr.2010.12.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 11/28/2010] [Accepted: 12/01/2010] [Indexed: 11/15/2022] Open
Abstract
In mammals, X chromosome inactivation (XCI) is a process in which one of the two X chromosomes is silenced, following XIST expression. Mouse female pluripotent stem cells do not express Xist, and harbor two active X chromosomes. However, analysis of XCI in human embryonic stem cells (hESCs), mainly based on XIST expression, was not conclusive. Here, we studied XCI in hESCs by meta-analysis of the expression of the entire set of genes on the X chromosome in 21 female hESC lines. Thus, we could divide the ES cell lines into three categories: lines with no XCI, lines with full XCI, and lines with partial XCI. The partial inactivation of the X chromosome always involved the middle of the chromosome, surrounding the XIST transcription site. The status of XCI in some of the cell lines was validated by either allelic-specific expression or DNA methylation analysis. Interestingly, analysis of 10 female human-induced pluripotent stem cell (hiPSC) lines demonstrated similar heterogeneity in the inactivation of X chromosome and could also be classified into the same three categories detected in hESCs. Thus, we could show that in some hiPSC lines, the X chromosome was activated on reprogramming. Based on our analysis, we propose a model of the dynamics of XCI in pluripotent stem cells.
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Affiliation(s)
- Tal Bruck
- Stem Cell Unit, Department of Genetics, Institute of Life Sciences, The Hebrew University, Edmund J. Safra Campus, Givat Ram, Jerusalem, 91904, Israel
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25
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A model for neural development and treatment of Rett syndrome using human induced pluripotent stem cells. Cell 2010; 143:527-39. [PMID: 21074045 DOI: 10.1016/j.cell.2010.10.016] [Citation(s) in RCA: 976] [Impact Index Per Article: 69.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 08/04/2010] [Accepted: 10/08/2010] [Indexed: 12/14/2022]
Abstract
Autism spectrum disorders (ASD) are complex neurodevelopmental diseases in which different combinations of genetic mutations may contribute to the phenotype. Using Rett syndrome (RTT) as an ASD genetic model, we developed a culture system using induced pluripotent stem cells (iPSCs) from RTT patients' fibroblasts. RTT patients' iPSCs are able to undergo X-inactivation and generate functional neurons. Neurons derived from RTT-iPSCs had fewer synapses, reduced spine density, smaller soma size, altered calcium signaling and electrophysiological defects when compared to controls. Our data uncovered early alterations in developing human RTT neurons. Finally, we used RTT neurons to test the effects of drugs in rescuing synaptic defects. Our data provide evidence of an unexplored developmental window, before disease onset, in RTT syndrome where potential therapies could be successfully employed. Our model recapitulates early stages of a human neurodevelopmental disease and represents a promising cellular tool for drug screening, diagnosis and personalized treatment.
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26
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Mitjavila-Garcia MT, Bonnet ML, Yates F, Haddad R, Oudrhiri N, Féraud O, Magniez A, Makhlouf M, Vallot C, Rougeulle C, Bennaceur-Griscelli A, Turhan AG. Partial reversal of the methylation pattern of the X-linked gene HUMARA during hematopoietic differentiation of human embryonic stem cells. J Mol Cell Biol 2010; 2:291-8. [PMID: 20823083 DOI: 10.1093/jmcb/mjq026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human embryonic stem cells (hESCs) can be induced to differentiate towards hematopoiesis with high efficiency. In this work, we analyzed the methylation status of the X-linked HUMARA (human androgen receptor) gene in hematopoietic cells derived from hESC line H9 before and after induction of hematopoietic differentiation. All passages of H9 and H9-derived hematopoietic cells displayed homogenous methylation pattern with disappearance of the same allele upon HpaII digestion. This pattern persisted in the great majority of different hematopoietic progenitors derived from H9, except in 11 of 86 individually plucked colonies in which an equal digestion of the HUMARA alleles has been found, suggesting that a methylation change occurring at this locus during differentiation. Interestingly, quantification of X inactive-specific transcript (XIST) RNA in undifferentiated H9 cell line and day 14 embryoid bodies (EB) by RT-PCR did not show any evidence of XIST expression either before or after differentiation. Thus, during self-renewal conditions and after induction of commitment towards the formation of EB, the methylation pattern of the HUMARA locus appears locked with the same unmethylated allele. However, hematopoietic differentiation seems to be permissive to the reversal of methylation status of HUMARA in some terminally differentiated progenitors. These data suggest that monitoring methylation of HUMARA gene during induced differentiation could be of use for studying hESC-derived hematopoiesis.
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27
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Tchieu J, Kuoy E, Chin MH, Trinh H, Patterson M, Sherman SP, Aimiuwu O, Lindgren A, Hakimian S, Zack JA, Clark AT, Pyle AD, Lowry WE, Plath K. Female human iPSCs retain an inactive X chromosome. Cell Stem Cell 2010; 7:329-42. [PMID: 20727844 DOI: 10.1016/j.stem.2010.06.024] [Citation(s) in RCA: 228] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 05/27/2010] [Accepted: 06/17/2010] [Indexed: 11/16/2022]
Abstract
Generating induced pluripotent stem cells (iPSCs) requires massive epigenome reorganization. It is unclear whether reprogramming of female human cells reactivates the inactive X chromosome (Xi), as in mouse. Here we establish that human (h)iPSCs derived from several female fibroblasts under standard culture conditions carry an Xi. Despite the lack of reactivation, the Xi undergoes defined chromatin changes, and expansion of hiPSCs can lead to partial loss of XIST RNA. These results indicate that hiPSCs are epigenetically dynamic and do not display a pristine state of X inactivation with two active Xs as found in some female human embryonic stem cell lines. Furthermore, whereas fibroblasts are mosaic for the Xi, hiPSCs are clonal. This nonrandom pattern of X chromosome inactivation in female hiPSCs, which is maintained upon differentiation, has critical implications for clinical applications and disease modeling, and could be exploited for a unique form of gene therapy for X-linked diseases.
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Affiliation(s)
- Jason Tchieu
- Department of Biological Chemistry, Jonsson Comprehensive Cancer Center, Molecular Biology Institute, David Geffen School of Medicine, and Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90024, USA
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28
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Medvedev S, Shevchenko A, Zakian S. Molecular basis of Mammalian embryonic stem cell pluripotency and self-renewal. Acta Naturae 2010; 2:30-46. [PMID: 22649650 PMCID: PMC3347565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Mammalian embryonic stem cells (ESC) have a number of specific properties that make them a unique object of fundamental and applied studies. In culture, ESC can remain in an infinitely undifferentiated state and differentiate into descendants of all three germ layers - ectoderm, endoderm, and mesoderm - that is, they can potentially produce more than 200 cell types comprising the body of an adult mammal. These properties of ESC are refered to as self-renewal and pluripotency. In this review, the basic signal pathways implicated in the maintenance of ESC pluripotency are considered. The major genes comprising a subsystem of "internal regulators of pluripotency," their protein products and regulators, are characterized, and interaction with other factors is described as well. The role of epigenetic mechanisms and microRNAs in the system of ESC self-renewal and pluripotency, as well as the relationship between pluripotency and X-chromosome inactivation in female mammals, is discussed.
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Affiliation(s)
- S.P. Medvedev
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences
| | - A.I. Shevchenko
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences
| | - S.M. Zakian
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences
- Research Center of Clinical and Experimental Medicine, Siberian Branch, Russian Academy of Medical Sciences
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29
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Dvash T, Lavon N, Fan G. Variations of X chromosome inactivation occur in early passages of female human embryonic stem cells. PLoS One 2010; 5:e11330. [PMID: 20593031 PMCID: PMC2892515 DOI: 10.1371/journal.pone.0011330] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 05/27/2010] [Indexed: 12/22/2022] Open
Abstract
X chromosome inactivation (XCI) is a dosage compensation mechanism essential for embryonic development and cell physiology. Human embryonic stem cells (hESCs) derived from inner cell mass (ICM) of blastocyst stage embryos have been used as a model system to understand XCI initiation and maintenance. Previous studies of undifferentiated female hESCs at intermediate passages have shown three possible states of XCI; 1) cells in a pre-XCI state, 2) cells that already exhibit XCI, or 3) cells that never undergo XCI even upon differentiation. In this study, XCI status was assayed in ten female hESC lines between passage 5 and 15 to determine whether XCI variations occur in early passages of hESCs. Our results show that three different states of XCI already exist in the early passages of hESC. In addition, we observe one cell line with skewed XCI and preferential expression of X-linked genes from the paternal allele, while another cell line exhibits random XCI. Skewed XCI in undifferentiated hESCs may be due to clonal selection in culture instead of non-random XCI in ICM cells. We also found that XIST promoter methylation is correlated with silencing of XIST transcripts in early passages of hESCs, even in the pre-XCI state. In conclusion, XCI variations already take place in early passages of hESCs, which may be a consequence of in vitro culture selection during the derivation process. Nevertheless, we cannot rule out the possibility that XCI variations in hESCs may reflect heterogeneous XCI states in ICM cells that stochastically give rise to hESCs.
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Affiliation(s)
- Tamar Dvash
- Department of Human Genetics and The Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Neta Lavon
- The International Stem Cell Research Institute, Cedars Sinai Medical Center, Los Angeles, California, United States of America
| | - Guoping Fan
- Department of Human Genetics and The Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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30
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Random X inactivation and extensive mosaicism in human placenta revealed by analysis of allele-specific gene expression along the X chromosome. PLoS One 2010; 5:e10947. [PMID: 20532033 PMCID: PMC2881032 DOI: 10.1371/journal.pone.0010947] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Accepted: 05/06/2010] [Indexed: 11/26/2022] Open
Abstract
Imprinted inactivation of the paternal X chromosome in marsupials is the primordial mechanism of dosage compensation for X-linked genes between females and males in Therians. In Eutherian mammals, X chromosome inactivation (XCI) evolved into a random process in cells from the embryo proper, where either the maternal or paternal X can be inactivated. However, species like mouse and bovine maintained imprinted XCI exclusively in extraembryonic tissues. The existence of imprinted XCI in humans remains controversial, with studies based on the analyses of only one or two X-linked genes in different extraembryonic tissues. Here we readdress this issue in human term placenta by performing a robust analysis of allele-specific expression of 22 X-linked genes, including XIST, using 27 SNPs in transcribed regions. We show that XCI is random in human placenta, and that this organ is arranged in relatively large patches of cells with either maternal or paternal inactive X. In addition, this analysis indicated heterogeneous maintenance of gene silencing along the inactive X, which combined with the extensive mosaicism found in placenta, can explain the lack of agreement among previous studies. Our results illustrate the differences of XCI mechanism between humans and mice, and highlight the importance of addressing the issue of imprinted XCI in other species in order to understand the evolution of dosage compensation in placental mammals.
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31
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Dhara SK, Gerwe BA, Majumder A, Dodla MC, Boyd NL, Machacek DW, Hasneen K, Stice SL. Genetic manipulation of neural progenitors derived from human embryonic stem cells. Tissue Eng Part A 2010; 15:3621-34. [PMID: 19795983 DOI: 10.1089/ten.tea.2009.0155] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Human embryonic stem cell-derived neural progenitors (NP) present an important tool for understanding human development and disease. Optimal utilization of NP cells, however, requires an enhanced ability to monitor these cells in vitro and in vivo. Here we report production of the first genetically modified self-renewing human embryonic stem cell-derived NP cells that express fluorescent proteins under constitutive as well as lineage-specific promoters, enabling tracking and monitoring of cell fate. Nucleofection, transfection, and lentiviral transduction were compared for optimal gene delivery to NP cells. Transduction was most efficient in terms of transgene expression (37%), cell viability (39%), and long-term reporter expression (>3 months). Further, the constitutive gene promoters, cytomegalovirus, elongation factor 1alpha, and ubiquitin-C, exhibited comparable silencing (20-30%) in NP cells over a 2-month period, suggesting their suitability for long-term reporter expression studies. Transduced NP cells maintained their progenitor state and differentiation potential, as demonstrated by expression of endogenous NP markers and neuronal markers after differentiation. We also detected reporter expression in astrocytes generated from NP cells transduced with an astrocyte-specific gene promoter, glial fibrillary acidic protein, demonstrating the usefulness of this approach. The genetically manipulated NP cells described here offer great potential for live cell-tracking experiments, and a similar approach can as well be used for expression of proteins other than reporters.
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Affiliation(s)
- Sujoy K Dhara
- Regenerative Bioscience Center, University of Georgia, Athens, Georgia 30602, USA
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32
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Shaw ML, Williams EJ, Hawes S, Saffery R. Characterisation of histone variant distribution in human embryonic stem cells by transfection of in vitro transcribed mRNA. Mol Reprod Dev 2010; 76:1128-42. [PMID: 19606468 DOI: 10.1002/mrd.21077] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recent studies, primarily in mouse embryonic stem cells, have highlighted the unique chromatin state of pluripotent stem cells, including the incorporation of histone variants into specific genomic locations, and its role in facilitating faithful expression of genes during development. However, there is little information available on the expression and subcellular localisation of histone variants in human embryonic stem cells (hESCs). In this study, we confirmed the expression of a panel of histone variant genes in several hESC lines and demonstrated the utility of transfection of in vitro transcribed, epitope-tagged mRNAs to characterise the subcellular localisation of these proteins. The subcellular localisations of variant histone H3 (CENP-A, H3.3), H2A (MACROH2A, H2AX, H2AZ, H2ABBD) and H1 (H1A, HB, H1C, H1D) were examined, revealing distinct nuclear localisation profiles for each protein. These data highlight the differences between murine (m) ESCs and hESCs, including the presence of a MACROH2A-enriched inactive X chromosome in undifferentiated XX hESC lines. We also provide the first evidence for MACROH2A accumulation on the Y-chromosome in XY hESCs.
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Affiliation(s)
- Margaret L Shaw
- Developmental Epigenetics, Department of Paediatrics, Murdoch Childrens Research Institute, Royal Children's Hospital, University of Melbourne, Parkville, Melbourne, Victoria, Australia
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33
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Barakat TS, Gribnau J. X chromosome inactivation and embryonic stem cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 695:132-54. [PMID: 21222204 DOI: 10.1007/978-1-4419-7037-4_10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
X chromosome inactivation (XCI) is a process required to equalize the dosage of X-encoded genes between female and male cells. XCI is initiated very early during female embryonic development or upon differentiation of female embryonic stem (ES) cells and results in inactivation of one X chromosome in every female somatic cell. The regulation of XCI involves factors that also play a crucial role in ES cell maintenance and differentiation and the XCI process therefore provides a beautiful paradigm to study ES cell biology. In this chapter we describe the important cis and trans acting regulators of XCI and introduce the models that have been postulated to explain initiation of XCI in female cells only. We also discuss the proteins involved in the establishment of the inactive X chromosome and describe the different chromatin modifications associated with the inactivation process. Finally, we describe the potential of mouse and human ES and induced pluripotent stem (iPS) cells as model systems to study the XCI process.
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Affiliation(s)
- Tahsin Stefan Barakat
- Department of Reproduction and Development, University Medical Center, Room Ee 09-71, Erasmus MC, 3015 GE, Rotterdam, Netherlands
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34
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Abstract
Gene trapping is a technology originally developed for the simultaneous identification and mutation of genes by random integration in embryonic stem (ES) cells. While gene trapping was developed before efficient and high-throughput gene targeting, a significant proportion of the publically available mutant ES cell lines and mice were generated through a number of large-scale gene trapping initiatives. Moreover, elements of gene trap vectors continue to be incorporated into gene targeting vectors as a means to increase the efficiency of homologous recombination. Here, we review the current state of gene trapping technology and the applications of specific types of gene trap vector. As a component of this analysis, we consider the behavior of specific vector types both from the perspective of their application and how they can inform our annotation of the mammalian transcriptome. We consider the utility of gene trap vectors as tools for cell-based expression analysis, targeted screening in embryonic differentiation, and for use in cell lines derived from different lineages.
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Affiliation(s)
- Joshua M Brickman
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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35
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Carpenter MK, Frey-Vasconcells J, Rao MS. Developing safe therapies from human pluripotent stem cells. Nat Biotechnol 2009; 27:606-13. [PMID: 19587662 DOI: 10.1038/nbt0709-606] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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36
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Abstract
Germ cells undergo comprehensive epigenetic reprogramming toward acquiring fitness for pluripotency and totipotency. Notably, the full extent of the epigenetic reprogramming experienced by germ cells remains unmatched by attempts to experimentally restore pluripotency in somatic cells. We propose that the defects present in experimentally generated cells are corrected upon differentiation into the germ cell lineage, as has been observed in cases of germline transmission. Unraveling the mechanisms responsible for germ cell-specific epigenetic reprogramming will likely have important implications for both basic and clinical stem cell research.
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Affiliation(s)
- Katsuhiko Hayashi
- Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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37
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van den Berg IM, Laven JS, Stevens M, Jonkers I, Galjaard RJ, Gribnau J, Hikke van Doorninck J. X chromosome inactivation is initiated in human preimplantation embryos. Am J Hum Genet 2009; 84:771-9. [PMID: 19481196 DOI: 10.1016/j.ajhg.2009.05.003] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 04/27/2009] [Accepted: 05/04/2009] [Indexed: 10/20/2022] Open
Abstract
X chromosome inactivation (XCI) is the mammalian mechanism that compensates for the difference in gene dosage between XX females and XY males. Genetic and epigenetic regulatory mechanisms induce transcriptional silencing of one X chromosome in female cells. In mouse embryos, XCI is initiated at the preimplantation stage following early whole-genome activation. It is widely thought that human embryos do not employ XCI prior to implantation. Here, we show that female preimplantation embryos have a progressive accumulation of XIST RNA on one of the two X chromosomes, starting around the 8-cell stage. XIST RNA accumulates at the morula and blastocyst stages and is associated with transcriptional silencing of the XIST-coated chromosomal region. These findings indicate that XCI is initiated in female human preimplantation-stage embryos and suggest that preimplantation dosage compensation is evolutionarily conserved in placental mammals.
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38
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Liu W, Sun X. Skewed X chromosome inactivation in diploid and triploid female human embryonic stem cells. Hum Reprod 2009; 24:1834-43. [DOI: 10.1093/humrep/dep126] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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39
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Abstract
Telomeric regions are known to be transcribed in several organisms. Although originally reported to be transcribed from all chromosomes with enrichment near the inactive X of female cells, we show that telomeric RNAs in fact are enriched on both sex chromosomes of the mouse in a developmentally specific manner. In female stem cells, both active Xs are marked by the RNAs. In male stem cells, both the X and the Y accumulate telomeric RNA. Distribution of telomeric RNAs changes during cell differentiation, after which they associate only with the heterochromatic sex chromosomes of each sex. FISH mapping suggests that accumulated telomeric RNAs localize at the distal telomeric end. Interestingly, telomeric expression changes in cancer and during cellular stress. Furthermore, RNA accumulation increases in Dicer-deficient stem cells, suggesting direct or indirect links to RNAi. We propose that telomeric RNAs are tied to cell differentiation and may be used to mark pluripotency and disease.
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40
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Urbach A, Benvenisty N. Studying early lethality of 45,XO (Turner's syndrome) embryos using human embryonic stem cells. PLoS One 2009; 4:e4175. [PMID: 19137066 PMCID: PMC2613558 DOI: 10.1371/journal.pone.0004175] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Accepted: 11/24/2008] [Indexed: 11/23/2022] Open
Abstract
Turner's syndrome (caused by monosomy of chromosome X) is one of the most common chromosomal abnormalities in females. Although 3% of all pregnancies start with XO embryos, 99% of these pregnancies terminate spontaneously during the first trimester. The common genetic explanation for the early lethality of monosomy X embryos, as well as the phenotype of surviving individuals is haploinsufficiency of pseudoautosomal genes on the X chromosome. Another possible mechanism is null expression of imprinted genes on the X chromosome due to the loss of the expressed allele. In contrast to humans, XO mice are viable, and fertile. Thus, neither cells from patients nor mouse models can be used in order to study the cause of early lethality in XO embryos. Human embryonic stem cells (HESCs) can differentiate in culture into cells from the three embryonic germ layers as well as into extraembryonic cells. These cells have been shown to have great value in modeling human developmental genetic disorders. In order to study the reasons for the early lethality of 45,XO embryos we have isolated HESCs that have spontaneously lost one of their sex chromosomes. To examine the possibility that imprinted genes on the X chromosome play a role in the phenotype of XO embryos, we have identified genes that were no longer expressed in the mutant cells. None of these genes showed a monoallelic expression in XX cells, implying that imprinting is not playing a major role in the phenotype of XO embryos. To suggest an explanation for the embryonic lethality caused by monosomy X, we have differentiated the XO HESCs in vitro an in vivo. DNA microarray analysis of the differentiated cells enabled us to compare the expression of tissue specific genes in XO and XX cells. The tissue that showed the most significant differences between the clones was the placenta. Many placental genes are expressed at much higher levels in XX cells in compare to XO cells. Thus, we suggest that abnormal placental differentiation as a result of haploinsufficiency of X-linked pseudoautosomal genes causes the early lethality in XO human embryos.
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Affiliation(s)
- Achia Urbach
- Department of Genetics, Silberman Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Nissim Benvenisty
- Department of Genetics, Silberman Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
- * E-mail:
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41
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Embryonic stem cells: isolation, characterization and culture. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2009; 114:173-84. [PMID: 19495683 DOI: 10.1007/10_2008_20] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Embryonic stem cells are pluripotent cells isolated from the mammalian blastocyst. Traditionally, these cells have been derived and cultured with mouse embryonic fibroblast (MEF) supportive layers, which allow their continuous growth in an undifferentiated state. However, for any future industrial or clinical application hESCs should be cultured in reproducible, defined, and xeno-free culture system, where exposure to animal pathogens is prevented. From their derivation in 1998 the methods for culturing hESCs were significantly improved. This chapter wills discuss hESC characterization and the basic methods for their derivation and maintenance.
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Hall LL, Byron M, Butler J, Becker KA, Nelson A, Amit M, Itskovitz-Eldor J, Stein J, Stein G, Ware C, Lawrence JB. X-inactivation reveals epigenetic anomalies in most hESC but identifies sublines that initiate as expected. J Cell Physiol 2008; 216:445-52. [PMID: 18340642 DOI: 10.1002/jcp.21411] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The clinical and research value of human embryonic stem cells (hESC) depends upon maintaining their epigenetically naïve, fully undifferentiated state. Inactivation of one X chromosome in each cell of mammalian female embryos is a paradigm for one of the earliest steps in cell specialization through formation of facultative heterochromatin. Mouse ES cells are derived from the inner cell mass (ICM) of blastocyst stage embryos prior to X-inactivation, and cultured murine ES cells initiate this process only upon differentiation. Less is known about human X-inactivation during early development. To identify a human ES cell model for X-inactivation and study differences in the epigenetic state of hESC lines, we investigated X-inactivation in all growth competent, karyotypically normal, NIH approved, female hESC lines and several sublines. In the vast majority of undifferentiated cultures of nine lines examined, essentially all cells exhibit hallmarks of X-inactivation. However, subcultures of any hESC line can vary in X-inactivation status, comprising distinct sublines. Importantly, we identified rare sublines that have not yet inactivated Xi and retain competence to undergo X-inactivation upon differentiation. Other sublines exhibit defects in counting or maintenance of XIST expression on Xi. The few hESC sublines identified that have not yet inactivated Xi may reflect the earlier epigenetic state of the human ICM and represent the most promising source of NIH hESC for study of human X-inactivation. The many epigenetic anomalies seen indicate that maintenance of fully unspecialized cells, which have not formed Xi facultative heterochromatin, is a delicate epigenetic balance difficult to maintain in culture.
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Affiliation(s)
- Lisa L Hall
- Department of Cell Biology, U Mass Med School, Worcester, Massachusetts 01655, USA.
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43
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Sun X, Long X, Yin Y, Jiang Y, Chen X, Liu W, Zhang W, Du H, Li S, Zheng Y, Kong S, Pang Q, Shi Y, Huang Y, Huang S, Liao B, Xiao G, Wang W. Similar biological characteristics of human embryonic stem cell lines with normal and abnormal karyotypes. Hum Reprod 2008; 23:2185-93. [PMID: 18611919 PMCID: PMC2538585 DOI: 10.1093/humrep/den137] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Human embryonic stem cell (hESC) lines derived from poor quality embryos usually have either normal or abnormal karyotypes. However, it is still unclear whether their biological characteristics are similar. METHODS Seven new hESC lines were established using discarded embryos. Five cell lines had normal karyotype, one was with an unbalanced Robertsonian translocation and one had a triploid karyotype. Their biological characteristics, short tandem repeat loci, HLA typing, differentiation capability and imprinted gene, DNA methylation and X chromosome inactivation status were compared between different cell lines. RESULTS All seven hESC lines had similar biological characteristics regardless of karyotype (five normal and two abnormal), such as expression of stage-specific embryonic antigen (SSEA)-4, tumor-rejection antigen (TRA)-1-81 and TRA-1-60 proteins, transcription factor octamer binding protein 4 mRNA, no detectable expression of SSEA-1 protein and high levels of alkaline phosphatase activity. All cell lines were able to undergo differentiation. Imprinted gene expression and DNA methylation were also similar among these cell lines. Non-random X chromosome inactivation patterns were found in XX cell lines. CONCLUSIONS The present results suggest that hESC lines with abnormal karyotype are also useful experimental materials for cell therapy, developmental biology and genetic research.
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Affiliation(s)
- Xiaofang Sun
- Institute of Gynecology and Obstetrics, The Third Affiliated Hospital of Guangzhou Medical College, Guangzhou, People's Republic of China.
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44
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X-inactivation in female human embryonic stem cells is in a nonrandom pattern and prone to epigenetic alterations. Proc Natl Acad Sci U S A 2008; 105:4709-14. [PMID: 18339804 DOI: 10.1073/pnas.0712018105] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
X chromosome inactivation (XCI) is an essential mechanism for dosage compensation of X-linked genes in female cells. We report that subcultures from lines of female human embryonic stem cells (hESCs) exhibit variation (0-100%) for XCI markers, including XIST RNA expression and enrichment of histone H3 lysine 27 trimethylation (H3K27me3) on the inactive X chromosome (Xi). Surprisingly, regardless of the presence or absence of XCI markers in different cultures, all female hESCs we examined (H7, H9, and HSF6 cells) exhibit a monoallelic expression pattern for a majority of X-linked genes. Our results suggest that these established female hESCs have already completed XCI during the process of derivation and/or propagation, and the XCI pattern of lines we investigated is already not random. Moreover, XIST gene expression in subsets of cultured female hESCs is unstable and subject to stable epigenetic silencing by DNA methylation. In the absence of XIST expression, approximately 12% of X-linked promoter CpG islands become hypomethylated and a portion of X-linked alleles on the Xi are reactivated. Because alterations in dosage compensation of X-linked genes could impair somatic cell function, we propose that XCI status should be routinely checked in subcultures of female hESCs, with cultures displaying XCI markers better suited for use in regenerative medicine.
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45
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X-chromosome inactivation and epigenetic fluidity in human embryonic stem cells. Proc Natl Acad Sci U S A 2008; 105:4820-5. [PMID: 18339803 DOI: 10.1073/pnas.0712136105] [Citation(s) in RCA: 222] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
With the potential to give rise to all somatic cell types, human embryonic stem cells (hESC) have generated enormous interest as agents of cell replacement therapy. One potential limitation is their safety in vivo. Although several studies have focused on concerns over genomic stability ex vivo, few have analyzed epigenetic stability. Here, we use tools of the epigenetic phenomenon, X-chromosome inactivation (XCI), to investigate their epigenetic properties. Among 11 distinct hESC lines, we find a high degree of variability. We show that, like mouse ESC, hESC in principle have the capacity to recapitulate XCI when induced to differentiate in culture (class I lines). However, this capacity is seen in few hESC isolates. Many hESC lines have already undergone XCI (class II and III). Unexpectedly, there is a tendency to lose XIST RNA expression during culture (class III). Despite losing H3-K27 trimethylation, the inactive X of class III lines remains transcriptionally suppressed, as indicated by Cot-1 RNA exclusion. We conclude that hESC lines are subject to dynamic epigenetic reprogramming ex vivo. Given that XCI and cell differentiation are tightly linked, we consider implications for hESC pluripotency and differentiation potential.
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46
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Pannetier M, Feil R. Epigenetic stability of embryonic stem cells and developmental potential. Trends Biotechnol 2007; 25:556-62. [PMID: 17983676 DOI: 10.1016/j.tibtech.2007.09.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Revised: 09/10/2007] [Accepted: 09/10/2007] [Indexed: 11/25/2022]
Abstract
Recent studies highlight the tremendous potential of human embryonic stem (ES) cells and their derivatives as therapeutic tools for degenerative diseases. However, derivation and culture of ES cells can induce epigenetic alterations, which can have long lasting effects on gene expression and phenotype. Research on human and mouse stem cells indicates that developmental, cancer-related genes, and genes regulated by genomic imprinting are particularly susceptible to changes in DNA methylation. Together with the occurrence of genetic alterations, epigenetic instability needs to be monitored when considering human stem cells for therapeutic and technological purposes. Here, we discuss the maintenance of epigenetic information in cultured stem cells and embryos and how this influences their developmental potential.
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Affiliation(s)
- Maëlle Pannetier
- Institute of Molecular Genetics, CNRS, 1919, route de Mende, 34293 Montpellier, France
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47
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Wutz A. Xist function: bridging chromatin and stem cells. Trends Genet 2007; 23:457-64. [PMID: 17681633 DOI: 10.1016/j.tig.2007.07.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 06/06/2007] [Accepted: 07/18/2007] [Indexed: 11/19/2022]
Abstract
In mammals, dosage compensation is achieved by transcriptional silencing of one of the two female X chromosomes. X inactivation is dynamically regulated in development. The non-coding Xist RNA localizes to the inactive X, initiates gene repression in the early embryo, and later stabilizes the inactive state. Different functions of Xist are observed depending on which epigenetic regulatory pathways are active in a given cell. Because Xist has evolved recently, with the origin of placental mammals, the underlying pathways are also important in regulating developmental control genes. This review emphasizes the opportunity that Xist provides to functionally define epigenetic transitions in development, to understand cell identity, pluripotency and stem cell differentiation.
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Affiliation(s)
- Anton Wutz
- Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria.
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48
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Adewumi O, Aflatoonian B, Ahrlund-Richter L, Amit M, Andrews PW, Beighton G, Bello PA, Benvenisty N, Berry LS, Bevan S, Blum B, Brooking J, Chen KG, Choo ABH, Churchill GA, Corbel M, Damjanov I, Draper JS, Dvorak P, Emanuelsson K, Fleck RA, Ford A, Gertow K, Gertsenstein M, Gokhale PJ, Hamilton RS, Hampl A, Healy LE, Hovatta O, Hyllner J, Imreh MP, Itskovitz-Eldor J, Jackson J, Johnson JL, Jones M, Kee K, King BL, Knowles BB, Lako M, Lebrin F, Mallon BS, Manning D, Mayshar Y, McKay RDG, Michalska AE, Mikkola M, Mileikovsky M, Minger SL, Moore HD, Mummery CL, Nagy A, Nakatsuji N, O'Brien CM, Oh SKW, Olsson C, Otonkoski T, Park KY, Passier R, Patel H, Patel M, Pedersen R, Pera MF, Piekarczyk MS, Pera RAR, Reubinoff BE, Robins AJ, Rossant J, Rugg-Gunn P, Schulz TC, Semb H, Sherrer ES, Siemen H, Stacey GN, Stojkovic M, Suemori H, Szatkiewicz J, Turetsky T, Tuuri T, van den Brink S, Vintersten K, Vuoristo S, Ward D, Weaver TA, Young LA, Zhang W. Characterization of human embryonic stem cell lines by the International Stem Cell Initiative. Nat Biotechnol 2007; 25:803-16. [PMID: 17572666 DOI: 10.1038/nbt1318] [Citation(s) in RCA: 770] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Accepted: 05/31/2007] [Indexed: 11/09/2022]
Abstract
The International Stem Cell Initiative characterized 59 human embryonic stem cell lines from 17 laboratories worldwide. Despite diverse genotypes and different techniques used for derivation and maintenance, all lines exhibited similar expression patterns for several markers of human embryonic stem cells. They expressed the glycolipid antigens SSEA3 and SSEA4, the keratan sulfate antigens TRA-1-60, TRA-1-81, GCTM2 and GCT343, and the protein antigens CD9, Thy1 (also known as CD90), tissue-nonspecific alkaline phosphatase and class 1 HLA, as well as the strongly developmentally regulated genes NANOG, POU5F1 (formerly known as OCT4), TDGF1, DNMT3B, GABRB3 and GDF3. Nevertheless, the lines were not identical: differences in expression of several lineage markers were evident, and several imprinted genes showed generally similar allele-specific expression patterns, but some gene-dependent variation was observed. Also, some female lines expressed readily detectable levels of XIST whereas others did not. No significant contamination of the lines with mycoplasma, bacteria or cytopathic viruses was detected.
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49
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Chow JC, Hall LL, Baldry SEL, Thorogood NP, Lawrence JB, Brown CJ. Inducible XIST-dependent X-chromosome inactivation in human somatic cells is reversible. Proc Natl Acad Sci U S A 2007; 104:10104-9. [PMID: 17537922 PMCID: PMC1891207 DOI: 10.1073/pnas.0610946104] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
During embryogenesis, the XIST RNA is expressed from and localizes to one X chromosome in females and induces chromosome-wide silencing. Although many changes to inactive X heterochromatin are known, the functional relationships between different modifications are not well understood, and studies of the initiation of X-inactivation have been largely confined to mouse. We now present a model system for human XIST RNA function in which induction of an XIST cDNA in somatic cells results in localized XIST RNA and transcriptional silencing. Chromatin immunoprecipitation and immunohistochemistry shows that this silencing need only be accompanied by a subset of heterochromatic marks and that these can differ between integration sites. Surprisingly, silencing is XIST-dependent, remaining reversible over extended periods. Deletion analysis demonstrates that the first exon of human XIST is sufficient for both transcript localization and the induction of silencing and that, unlike the situation in mice, the conserved repeat region is essential for both functions. In addition to providing mechanistic insights into chromosome regulation and formation of facultative heterochromatin, this work provides a tractable model system for the study of chromosome silencing and suggests key differences from mouse embryonic X-inactivation.
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MESH Headings
- Chromatin Immunoprecipitation
- Chromosomes, Human, X/genetics
- Chromosomes, Human, X/metabolism
- DNA Methylation
- DNA, Complementary
- Dosage Compensation, Genetic
- Doxycycline/pharmacology
- Fibrosarcoma/pathology
- Gene Silencing
- Heterochromatin
- Histones/chemistry
- Histones/metabolism
- Humans
- Immunohistochemistry
- In Situ Hybridization, Fluorescence
- Models, Genetic
- RNA, Long Noncoding
- RNA, Untranslated
- Sequence Analysis, DNA
- X Chromosome Inactivation
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Affiliation(s)
- Jennifer C. Chow
- *Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T1Z3; and
| | - Lisa L. Hall
- University of Massachusetts Medical Center, Worcester, MA 01655
| | - Sarah E. L. Baldry
- *Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T1Z3; and
| | - Nancy P. Thorogood
- *Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T1Z3; and
| | | | - Carolyn J. Brown
- *Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T1Z3; and
- To whom correspondence should be addressed at:
Department of Medical Genetics, Molecular Epigenetics Group, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3. E-mail:
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50
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Baker DEC, Harrison NJ, Maltby E, Smith K, Moore HD, Shaw PJ, Heath PR, Holden H, Andrews PW. Adaptation to culture of human embryonic stem cells and oncogenesis in vivo. Nat Biotechnol 2007; 25:207-15. [PMID: 17287758 DOI: 10.1038/nbt1285] [Citation(s) in RCA: 470] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The application of human embryonic stem cells (HESCs) to provide differentiated cells for regenerative medicine will require the continuous maintenance of the undifferentiated stem cells for long periods in culture. However, chromosomal stability during extended passaging cannot be guaranteed, as recent cytogenetic studies of HESCs have shown karyotypic aberrations. The observed karyotypic aberrations probably reflect the progressive adaptation of self-renewing cells to their culture conditions. Genetic change that increases the capacity of cells to proliferate has obvious parallels with malignant transformation, and we propose that the changes observed in HESCs in culture reflect tumorigenic events that occur in vivo, particularly in testicular germ cell tumors. Further supporting a link between culture adaptation and malignancy, we have observed the formation of a chromosomal homogeneous staining region in one HESC line, a genetic feature almost a hallmark of cancer cells. Identifying the genes critical for culture adaptation may thus reveal key players for both stem cell maintenance in vitro and germ cell tumorigenesis in vivo.
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Affiliation(s)
- Duncan E C Baker
- Sheffield Regional Cytogenetics Service, Sheffield Children's Trust, Western Bank, Sheffield S10 2TH, UK
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