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 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’.

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 In vivo footprinting and high-resolution methylation analysis of the mouse hypoxanthine phosphoribosyltransferase gene 5' region on the active and inactive X chromosomes.

1996 ◽  
Vol 16 (11) ◽  
pp. 6190-6199 ◽  
Author(s):  
M D Litt ◽  
I K Hornstra ◽  
T P Yang
Keyword(s):  
High Resolution ◽  
X Chromosome ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Genomic Sequencing ◽  
Hypoxanthine Phosphoribosyltransferase ◽  
Hprt Gene ◽  
Methylation Analysis ◽  
In Vivo Footprinting

To investigate potential mechanisms regulating the hypoxanthine phosphoribosyltransferase (HPRT) gene by X-chromosome inactivation, we performed in vivo footprinting and high-resolution DNA methylation analysis on the 5' region of the active and inactive mouse HPRT alleles and compared these results with those from the human HPRT gene. We found multiple footprinted sites on the active mouse HPRT allele and no footprints on the inactive allele. Comparison of the footprint patterns of the mouse and human HPRT genes demonstrated that the in vivo binding of regulatory proteins between these species is generally conserved but not identical. Detailed nucleotide sequence comparison of footprinted regions in the mouse and human genes revealed a novel 9-bp sequence associated with transcription factor binding near the transcription sites of both genes, suggesting the identification of a new conserved initiator element. Ligation-mediated PCR genomic sequencing showed that all CpG dinucleotides examined on the active allele are unmethylated, while the majority of CpGs on the inactive allele are methylated and interspersed with a few hypomethylated sites. This pattern of methylation on the inactive mouse allele is notably different from the unusual methylation pattern of the inactive human gene, which exhibited strong hypomethylation specifically at GC boxes. These studies, in conjunction with other genomic sequencing studies of X-linked genes, demonstrate that (i) the active alleles are essentially unmethylated, (ii) the inactive alleles are hypermethylated, and (iii) the high-resolution methylation patterns of the hypermethylated inactive alleles are not strictly conserved. There is no obvious correlation between the pattern of methylated sites on the inactive alleles and the pattern of binding sites for transcription factors on the active alleles. These results are discussed in relationship to potential mechanisms of transcriptional regulation by X-chromosome inactivation.

X–chromosome inactivation during differentiation of female teratocarcinoma stem cells in vitro

Nature ◽  
1978 ◽  
Vol 271 (5643) ◽  
pp. 329-333 ◽  
Author(s):  
Gail R. Martin ◽  
Charles J. Epstein ◽  
Bruce Travis ◽  
Georgianne Tucker ◽  
Shaul Yatziv ◽  
...  
Keyword(s):  
Stem Cells ◽  
X Chromosome ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation

Multiple in vivo footprints are specific to the active allele of the X-linked human hypoxanthine phosphoribosyltransferase gene 5' region: implications for X chromosome inactivation

1992 ◽  
Vol 12 (12) ◽  
pp. 5345-5354
Author(s):  
I K Hornstra ◽  
T P Yang
Keyword(s):  
X Chromosome ◽  
Protein Interactions ◽  
Cultured Cells ◽  
Dimethyl Sulfate ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Hypoxanthine Phosphoribosyltransferase ◽  
Hprt Gene ◽  
Active Allele

Dosage compensation of X-linked genes in male and female mammals is accomplished by random inactivation of one X chromosome in each female somatic cell. As a result, a transcriptionally active allele and a transcriptionally inactive allele of most X-linked genes reside within each female nucleus. To examine the mechanism responsible for maintaining this unique system of differential gene expression, we have analyzed the differential binding of regulatory proteins to the 5' region of the human hypoxanthine phosphoribosyltransferase (HPRT) gene on the active and inactive X chromosomes. Studies of DNA-protein interactions associated with the transcriptionally active and inactive HPRT alleles were carried out in intact cultured cells by in vivo footprinting by using ligation-mediated polymerase chain reaction and dimethyl sulfate. Analysis of the active allele demonstrates at least six footprinted regions, whereas no footprints were detected on the inactive allele. Of the footprints on the active allele, at least four occur over canonical GC boxes or Sp1 consensus binding sites, one is associated with a potential AP-2 binding site, and another is associated with a DNA sequence not previously reported to interact with a sequence-specific DNA-binding factor. While no footprints were observed for the HPRT gene on the inactive X chromosome, reactivation of the inactive allele with 5-azacytidine treatment restored the in vivo footprint pattern found on the active allele. Results of these experiments, in conjunction with recent studies on the X-linked human PGK-1 gene, bear implications for models of X chromosome inactivation.

scholarly journals A Functional Mutation in HDAC8 Gene as Novel Diagnostic Marker for Cornelia De Lange Syndrome

2018 ◽  
Vol 47 (6) ◽  
pp. 2388-2395 ◽  
Author(s):  
Xueren Gao ◽  
Zhuo Huang ◽  
Yanjie Fan ◽  
Yu Sun ◽  
Huili Liu ◽  
...  
Keyword(s):  
Missense Mutation ◽  
X Chromosome ◽  
Genetic Disorder ◽  
Sodium Dodecyl ◽  
Pathogenic Mutation ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Cornelia De Lange Syndrome ◽  
Cornelia De Lange

Background/Aims: Cornelia de Lange Syndrome (CdLS) is a rare genetic disorder classically characterized by distinctive facies, growth retardation, intellectual disability, feeding difficulties, and multiple organ system anomalies. Previously, the diagnosis of CdLS was based mainly on identifying the typical phenotype in patients. However, with the advances in clinical molecular genetic diagnostic techniques, more patients, especially patients with milder phenotypes, are being diagnosed from detecting pathogenic mutation. Methods: Pathogenic mutation in a female patient with a milder phenotype was detected using whole-exome sequencing (WES), and was further characterized using bioinformatic analysis and in vitro functional experiments, including X-chromosome inactivation analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and enzyme activity assay. Results: This patient was found to harbor a novel missense mutation (c.806T>G, p.I269R) in the coding region of the HDAC8 gene, which was predicted to be pathogenic. Compared with other CdLS patients with HDAC8 mutation, the patient lacked typical facies, including synophrys and arched eyebrows. In vitro functional experiments showed the presence of skewed X-chromosome inactivation. Furthermore, the novel mutation decreased the dissolubility and enzymatic activity of HDAC8 protein. Conclusions: The present study identified a novel missense mutation (c.806T>G, p.I269R) in the HDAC8 gene leading to CdLS, which not only provided strong evidence for diagnosis in this present patient, but also expanded the spectrum of pathogenic mutations for CdLS.

Sign in / Sign up

Export Citation Format

Share Document