scholarly journals Human X chromosome inactivation and reactivation: implications for cell reprogramming and disease

2017 ◽  
Vol 372 (1733) ◽  
pp. 20160358 ◽  
Author(s):  
Irene Cantone ◽  
Amanda G. Fisher
Keyword(s):  
Cell Fusion ◽  
X Chromosome ◽  
Expression Profiles ◽  
Es Cells ◽  
Human Fibroblasts ◽  
Embryonic Stem ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation

X-chromosome inactivation (XCI) is an exemplar of epigenetic regulation that is set up as pluripotent cells differentiate. Once established, XCI is stably propagated, but can be reversed in vivo or by pluripotent reprogramming in vitro . Although reprogramming provides a useful model for inactive X (Xi) reactivation in mouse, the relative instability and heterogeneity of human embryonic stem (ES) cells and induced pluripotent stem cells hampers comparable progress in human. Here we review studies aimed at reactivating the human Xi using different reprogramming strategies. We outline our recent results using mouse ES cells to reprogramme female human fibroblasts by cell–cell fusion. We show that pluripotent reprogramming induces widespread and rapid chromatin remodelling in which the human Xi loses XIST and H3K27m3 enrichment and selected Xi genes become reactivated, ahead of mitotic division. Using RNA sequencing to map the extent of human Xi reactivation, and chromatin-modifying drugs to potentiate reactivation, we outline how this approach could be used to better design strategies to re-express human X-linked loci. As cell fusion induces the expression of human pluripotency genes that represent both the ‘primed’ and ‘naive’ states, this approach may also offer a fresh opportunity to segregate human pluripotent states with distinct Xi expression profiles, using single-cell-based approaches. This article is part of the themed issue ‘X-chromosome inactivation: a tribute to Mary Lyon’.

scholarly journals Progress and Future Challenges of Human Induced Pluripotents Stem Cell in Regenerative Medicine

2011 ◽  
Vol 3 (2) ◽  
pp. 76
Author(s):  
Anna Meiliana ◽  
Andi Wijaya
Keyword(s):  
Stem Cells ◽  
Somatic Cell ◽  
Expression Profiles ◽  
Human Fibroblasts ◽  
Embryonic Stem ◽  
Cell Types ◽  
Differentiation Potential ◽  
Human Ipscs

BACKGROUND: Less than a decade ago the prospect for reprogramming the human somatic cell looked bleak at best. It seemed that the only methods at our disposal for the generation of human isogenic pluripotent cells would have to involve somatic cell nuclear transfer (SCNT). Shinya Yamanaka in August 2006 in his publication (Cell) promised to change everything by showing that it was apparently very simple to revert the phenotype of a differentiated cell to a pluripotent one by overexpressing four transcription factors in murine fibroblasts.CONTENT: Mouse and human somatic cells can be genetically reprogrammed into induced pluripotent stem cells (iPSCs) by the expression of a defined set of factors (Oct4, Sox2, c-Myc, and Klf4, as well as Nanog and LIN28). iPSCs could be generated from mouse and human fibroblasts as well as from mouse liver, stomach, pancreatic, neural stem cells, and keratinocytes. Similarity of iPSCs and embryonic stem cells (ESCs) has been demonstrated in their morphology, global expression profiles, epigenetic status, as well as in vitro and in vivo differentiation potential for both mouse and human cells. Many techniques for human iPSCs (hiPSCs) derivation have been developed in recent years, utilizing different starting cell types, vector delivery systems, and culture conditions. A refined or perfected combination of these techniques might prove to be the key to generating clinically applicable hiPSCs.SUMMARY: iPSCs are a revolutionary tool for generating in vitro models of human diseases and may help us to understand the molecular basis of epigenetic reprogramming. Progress of the last four years has been truly amazing, almost verging on science fiction, but if we can learn to produce such cells cheaply and easily, and control their differentiation, our efforts to understand and fight disease will become more accessible, controllable and tailored. Ability to safely and efficiently derive hiPSCs may be of decisive importance to the future of regenerative medicine.KEYWORDS: iPSCs, ESC, reprogramming factor, reprogramming efficiency, somatic cell

scholarly journals Xmas ESC: A new female embryonic stem cell system that reveals the BAF complex as a key regulator of the establishment of X chromosome inactivation

2019 ◽  
Author(s):  
Andrew Keniry ◽  
Natasha Jansz ◽  
Linden J. Gearing ◽  
Iromi Wanigasuriya ◽  
Joseph Chen ◽  
...  
Keyword(s):  
X Chromosome ◽  
Embryonic Stem ◽  
X Chromosome Inactivation ◽  
Cell System ◽  
X Inactivation ◽  
Chromosome Inactivation ◽  
Baf Complex ◽  
Specific Process ◽  
Female Specific

SummaryAlthough female pluripotency significantly differs to male, complications with in vitro culture of female embryonic stem cells (ESC) have severely limited the use and study of these cells. We report a replenishable female ESC system, Xmas, that has enabled us to optimise a protocol for preserving the XX karyotype. Our protocol also improves male ESC fitness. We utilised our Xmas ESC system to screen for regulators of the female-specific process of X chromosome inactivation, revealing chromatin remodellers Smarcc1 and Smarca4 as key regulators of establishment of X inactivation. The remodellers create a nucleosome depleted region at gene promotors on the inactive X during exit from pluripotency, without which gene silencing fails. Our female ESC system provides a tractable model for XX ESC culture that will expedite study of female pluripotency and has enabled us to discover new features of the female-specific process of X inactivation.

scholarly journals Epigenetic-structural changes in X chromosomes promote Xic pairing during early differentiation from mouse embryonic stem cells

2021 ◽  
Author(s):  
Tetsushi Komoto ◽  
Masashi Fujii ◽  
Akinori Awazu
Keyword(s):  
X Chromosome ◽  
Structural Changes ◽  
Es Cells ◽  
Embryonic Stem ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Coarse Grained ◽  
Dynamics Model ◽  
X Chromosomes ◽  
Inactivation Center

X chromosome inactivation center (Xic) pairing is robustly observed during the differentiation of embryonic stem (ES) cells from female mouse embryos, and this process is related to X chromosome inactivation, the circadian clock, intra-nucleus architecture, and metabolism. However, the mechanisms underlying the identification and approach of X chromosome pairs in the crowded nucleus are unclear. To elucidate the driving force of Xic pairing, we developed a coarse-grained molecular dynamics model of intranuclear chromosomes in ES cells and in cells 2 days after the onset of differentiation (2-days cells) by considering intrachromosome epigenetic-structural feature-dependent mechanics. The analysis of the experimental data showed X-chromosomes change to specifically softer than autosomes during the cell differentiation by the rearrangement of their distributions of open-close chromatin regions, and the simulations of these models exhibited such softening promoted the mutual approach of the Xic pair. These findings suggested that local intrachromosomal epigenetic features may contribute to the regulation of cell species-dependent differences in intranuclear architecture.

scholarly journals A novel approach to differentiate rat embryonic stem cells in vitro reveals a role for RNF12 in activation of X chromosome inactivation

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Aristea Magaraki ◽  
Agnese Loda ◽  
Cristina Gontan ◽  
Sarra Merzouk ◽  
Esther Sleddens-Linkels ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
X Chromosome ◽  
Embryonic Stem ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Novel Approach

scholarly journals The Pluripotency Factor-Bound Intron 1 of Xist Is Dispensable for X Chromosome Inactivation and Reactivation In Vitro and In Vivo

Cell Reports ◽  
2013 ◽  
Vol 3 (3) ◽  
pp. 905-918 ◽  
Author(s):  
Alissa Minkovsky ◽  
Tahsin Stefan Barakat ◽  
Nadia Sellami ◽  
Mark Henry Chin ◽  
Nilhan Gunhanlar ◽  
...  
Keyword(s):  
X Chromosome ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Intron 1 ◽  
Pluripotency Factor

scholarly journals A temporally controlled sequence of X-chromosome inactivation and reactivation defines female mouse in vitro germ cells with meiotic potential

2021 ◽  
Author(s):  
Jacqueline Severino ◽  
Moritz Bauer ◽  
Tom Mattimoe ◽  
Niccolo Arecco ◽  
Luca Cozzuto ◽  
...  
Keyword(s):  
Germ Cell ◽  
X Chromosome ◽  
Female Mouse ◽  
Primordial Germ Cell ◽  
Embryonic Stem ◽  
X Chromosome Inactivation ◽  
Epigenetic Reprogramming ◽  
X Inactivation ◽  
Chromosome Inactivation

The early mammalian germ cell lineage is characterized by extensive epigenetic reprogramming, which is required for the maturation into functional eggs and sperm. In particular, the epigenome needs to be reset before parental marks can be established and then transmitted to the next generation. In the female germ line, reactivation of the inactive X chromosome is one of the most prominent epigenetic reprogramming events, and despite its scale involving an entire chromosome affecting hundreds of genes, very little is known about its kinetics and biological function. Here we investigate X-chromosome inactivation and reactivation dynamics by employing a tailor-made in vitro system to visualize the X-status during differentiation of primordial germ cell-like cells (PGCLCs) from female mouse embryonic stem cells (ESCs). We find that the degree of X-inactivation in PGCLCs is moderate when compared to somatic cells and characterized by a large number of genes escaping full inactivation. Nevertheless, PGCLCs that fail to undergo X-inactivation show an abnormal gene expression signature and deficiencies in meiotic entry. Subsequent to X-inactivation we observe gradual step-wise X-reactivation, which is mostly completed by the end of meiotic prophase I. Cells deviating from these progressive kinetics and undergoing X-reactivation too rapidly fail to enter a meiotic trajectory. Our data reveals that a fine-tuned X-inactivation and -reactivation cycle is a critical feature of female germ cell developmental competence towards meiosis and oogenesis

Brachyury - a gene affecting mouse gastrulation and early organogenesis

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 157-165 ◽  
Author(s):  
R. S. P. Beddington ◽  
P. Rashbass ◽  
V. Wilson
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Coat Colour ◽  
Es Cell ◽  
Wild Type ◽  
Mesoderm Cell ◽  
Rostrocaudal Axis

Mouse embryos that are homozygous for the Brachyury (T) deletion die at mid-gestation. They have prominent defects in the notochord, the allantois and the primitive streak. Expression of the T gene commences at the onset of gastrulation and is restricted to the primitive streak, mesoderm emerging from the streak, the head process and the notochord. Genetic evidence has suggested that there may be an increasing demand for T gene function along the rostrocaudal axis. Experiments reported here indicate that this may not be the case. Instead, the gradient in severity of the T defect may be caused by defective mesoderm cell movements, which result in a progressive accumulation of mesoderm cells near the primitive streak. Embryonic stem (ES) cells which are homozygous for the T deletion have been isolated and their differentiation in vitro and in vivo compared with that of heterozygous and wild-type ES cell lines. In +/+ ↔ T/T ES cell chimeras the Brachyury phenotype is not rescued by the presence of wild-type cells and high level chimeras show most of the features characteristic of intact T/T mutants. A few offspring from blastocysts injected with T/T ES cells have been born, several of which had greatly reduced or abnormal tails. However, little or no ES cell contribution was detectable in these animals, either as coat colour pigmentation or by isozyme analysis. Inspection of potential +/+ ↔ T/T ES cell chimeras on the 11th or 12th day of gestation, stages later than that at which intact T/T mutants die, revealed the presence of chimeras with caudal defects. These chimeras displayed a gradient of ES cell colonisation along the rostrocaudal axis with increased colonisation of caudal regions. In addition, the extent of chimerism in ectodermal tissues (which do not invaginate during gastrulation) tended to be higher than that in mesodermal tissues (which are derived from cells invaginating through the primitive streak). These results suggest that nascent mesoderm cells lacking the T gene are compromised in their ability to move away from the primitive streak. This indicates that one function of the T genemay be to regulate cell adhesion or cell motility properties in mesoderm cells. Wild-type cells in +/+ ↔ T/T chimeras appear to move normally to populate trunk and head mesoderm, suggesting that the reduced motility in T/T cells is a cell autonomous defect

X-chromosome reactivation: a concise review

2021 ◽  
Author(s):  
Alessandra Spaziano ◽  
Dr Irene Cantone
Keyword(s):  
X Chromosome ◽  
X Chromosome Inactivation ◽  
Epigenetic Modifications ◽  
X Chromosomes ◽  
Cell Divisions ◽  
Concise Review ◽  
Inactive X Chromosome ◽  
Silencing Pathways

Mammalian females (XX) silence transcription on one of the two X chromosomes to compensate the expression dosage with males (XY). This process — named X-chromosome inactivation — entails a variety of epigenetic modifications that act synergistically to maintain silencing and make it heritable through cell divisions. Genes along the inactive X chromosome are, indeed, refractory to reactivation. Nonetheless, X-chromosome reactivation can occur alongside with epigenome reprogramming or by perturbing multiple silencing pathways. Here we review the events associated with X-chromosome reactivation during in vivo and in vitro reprogramming and highlight recent efforts in inducing Xi reactivation by molecular perturbations. This provides us with a first understanding of the mechanisms underlying X-chromosome reactivation, which could be tackled for therapeutic purposes.

scholarly journals Generation and Characterization of Smac/DIABLO-Deficient Mice

2002 ◽  
Vol 22 (10) ◽  
pp. 3509-3517 ◽  
Author(s):  
Hitoshi Okada ◽  
Woong-Kyung Suh ◽  
Jianping Jin ◽  
Minna Woo ◽  
Chunying Du ◽  
...  
Keyword(s):  
Physiological Function ◽  
Es Cells ◽  
Embryonic Stem ◽  
Caspase Activation ◽  
Proapoptotic Protein ◽  
Apoptosis Proteins ◽  
Deficient Mice

ABSTRACT The mitochondrial proapoptotic protein Smac/DIABLO has recently been shown to potentiate apoptosis by counteracting the antiapoptotic function of the inhibitor of apoptosis proteins (IAPs). In response to apoptotic stimuli, Smac is released into the cytosol and promotes caspase activation by binding to IAPs, thereby blocking their function. These observations have suggested that Smac is a new regulator of apoptosis. To better understand the physiological function of Smac in normal cells, we generated Smac-deficient (Smac−/− ) mice by using homologous recombination in embryonic stem (ES) cells. Smac−/− mice were viable, grew, and matured normally and did not show any histological abnormalities. Although the cleavage in vitro of procaspase-3 was inhibited in lysates of Smac−/− cells, all types of cultured Smac−/− cells tested responded normally to all apoptotic stimuli applied. There were also no detectable differences in Fas-mediated apoptosis in the liver in vivo. Our data strongly suggest the existence of a redundant molecule or molecules capable of compensating for a loss of Smac function.

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