scholarly journals Histone Macroh2a1.2 Relocates to the Inactive X Chromosome after Initiation and Propagation of X-Inactivation

1999 ◽  
Vol 147 (7) ◽  
pp. 1399-1408 ◽  
Author(s):  
Jacqueline E. Mermoud ◽  
Carl Costanzi ◽  
John R. Pehrson ◽  
Neil Brockdorff
Keyword(s):  
X Chromosome ◽  
Es Cells ◽  
Embryonic Stem ◽  
X Inactivation ◽  
Dense Region ◽  
Rich Domain ◽  
Inactive X Chromosome ◽  
Initiation And Propagation ◽  
Xist Rna

The histone macroH2A1.2 has been implicated in X chromosome inactivation on the basis of its accumulation on the inactive X chromosome (Xi) of adult female mammals. We have established the timing of macroH2A1.2 association with the Xi relative to the onset of X-inactivation in differentiating murine embryonic stem (ES) cells using immuno-RNA fluorescence in situ hybridization (FISH). Before X-inactivation we observe a single macroH2A1.2-dense region in both undifferentiated XX and XY ES cells that does not colocalize with X inactive specific transcript (Xist) RNA, and thus appears not to associate with the X chromosome(s). This pattern persists through early stages of differentiation, up to day 7. Then the frequency of XY cells containing a macroH2A1.2-rich domain declines. In contrast, in XX cells there is a striking relocalization of macroH2A1.2 to the Xi. Relocalization occurs in a highly synchronized wave over a 2-d period, indicating a precisely regulated association. The timing of macroH2A1.2 accumulation on the Xi suggests it is not necessary for the initiation or propagation of random X-inactivation.

scholarly journals Induction of X-chromosome Inactivation by the Histone Demethylase SMCX/KDM5C

2017 ◽  
Author(s):  
Srimonta Gayen ◽  
Emily Maclary ◽  
Yumie Murata-Nakamura ◽  
Christina N. Vallianatos ◽  
Robert S. Porter ◽  
...  
Keyword(s):  
X Chromosome ◽  
Embryonic Stem ◽  
Histone Demethylase ◽  
X Inactivation ◽  
Linked Gene ◽  
Xist Rna ◽  
Evolutionarily Conserved ◽  
Specific Induction ◽  
Female Specific ◽  
Dose Dependent

SUMMARYXY male and XX female mammals equalize X-linked gene expression through the mitotically-stable transcriptional inactivation of an X-chromosome in females. Although most genes are silent on the inactive-X, some escape silencing and are expressed at higher levels in females vs. males. Here, we show that the escapee Smcx/Kdm5c, encoding a histone H3K4me2/3 demethylase, underlies the female-specific induction of X-inactivation. Mouse embryonic epiblast cells and differentiating embryonic stem cells (ESCs) lacking SMCX show reduced expression of Xist RNA, which is required for X-inactivation. Smcx-heterozygous epiblast cells do not silence X-linked genes efficiently, despite robust Xist expression. Overexpression of mouse or human SMCX, but not a catalytically-inactive SMCX or the Y-chromosome homolog SMCY, is sufficient to induce Xist and, separately, to silence X-linked genes in male ESCs. Finally, SMCX dose is inversely correlated with H3K4me2 at X-linked loci. Thus, X-inactivation initiates through the evolutionarily conserved, dose-dependent function of the histone demethylase SMCX.

An X-linked human collagen transgene escapes X inactivation in a subset of cells

Development ◽  
1992 ◽  
Vol 116 (3) ◽  
pp. 687-695
Author(s):  
H. Wu ◽  
R. Fassler ◽  
A. Schnieke ◽  
D. Barker ◽  
K.H. Lee ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
X Chromosome ◽  
Transgene Expression ◽  
Cultured Cells ◽  
X Inactivation ◽  
Small Subset ◽  
Collagen Gene ◽  
Inactive X Chromosome ◽  
Human Collagen

Transgenic mice carrying one complete copy of the human alpha 1(I) collagen gene on the X chromosome (HucII mice) were used to study the effect of X inactivation on transgene expression. By chromosomal in situ hybridization, the transgene was mapped to the D/E region close to the Xce locus, which is the controlling element. Quantitative RNA analyses indicated that transgene expression in homozygous and heterozygous females was about 125% and 62%, respectively, of the level found in hemizygous males. Also, females with Searle's translocation carrying the transgene on the inactive X chromosome (Xi) expressed about 18% transgene RNA when compared to hemizygous males. These results were consistent with the transgene being subject to but partially escaping from X inactivation. Two lines of evidence indicated that the transgene escaped X inactivation or was reactivated in a small subset of cells rather than being expressed at a lower level from the Xi in all cells, (i) None of nine single cell clones carrying the transgene on the Xi transcribed transgene RNA. In these clones the transgene was highly methylated in contrast to clones carrying the transgene on the Xa. (ii) In situ hybridization to RNA of cultured cells revealed that about 3% of uncloned cells with the transgene on the Xi expressed transgene RNA at a level comparable to that on the Xa. Our results indicate that the autosomal human collagen gene integrated on the mouse X chromosome is susceptible to X inactivation. Inactivation is, however, not complete as a subset of cells carrying the transgene on Xi expresses the transgene at a level comparable to that when carried on Xa.

scholarly journals Xist RNA Is Confined to the Nuclear Territory of the Silenced X Chromosome throughout the Cell Cycle

2008 ◽  
Vol 28 (18) ◽  
pp. 5583-5594 ◽  
Author(s):  
Iris Jonkers ◽  
Kim Monkhorst ◽  
Eveline Rentmeester ◽  
J. Anton Grootegoed ◽  
Frank Grosveld ◽  
...  
Keyword(s):  
Cell Cycle ◽  
X Chromosome ◽  
Es Cells ◽  
Embryonic Stem ◽  
Chromosome Analysis ◽  
Tetraploid Cell ◽  
Mouse Es Cells ◽  
Xist Rna ◽  
Mammalian Female ◽  
Dose Difference

ABSTRACT In mammalian female cells, one X chromosome is inactivated to prevent a dose difference in the expression of X-encoded proteins between males and females. Xist RNA, required for X chromosome inactivation, is transcribed from the future inactivated X chromosome (Xi), where it spreads in cis, to initiate silencing. We have analyzed Xist RNA transcription and localization throughout the cell cycle. It was found that Xist transcription is constant and that the mature RNA remains attached to the Xi throughout mitosis. Diploid and tetraploid cell lines with an MS2-tagged Xist gene were used to investigate spreading of Xist. Most XXXXMS2 tetraploid mouse embryonic stem (ES) cells inactivate the XMS2 chromosome and one other X chromosome. Analysis of cells with two Xi's indicates that Xist RNA is retained by the Xi of its origin and does not spread in trans. Also, in XXMS2 diploid mouse ES cells with an autosomal Xist transgene, there is no trans exchange of Xist RNA from the Xi to the autosome. We propose that Xist RNA does not dissociate from the Xi of its origin, which precludes a model of diffusion-mediated trans spreading of Xist RNA.

scholarly journals Species-specific differences in X chromosome inactivation in mammals

Reproduction ◽  
2013 ◽  
Vol 146 (4) ◽  
pp. R131-R139 ◽  
Author(s):  
Takashi Sado ◽  
Takehisa Sakaguchi
Keyword(s):  
X Chromosome ◽  
Molecular Basis ◽  
Embryonic Stem ◽  
X Chromosome Inactivation ◽  
X Inactivation ◽  
Chromosome Inactivation ◽  
X Chromosomes ◽  
Inactive X Chromosome ◽  
Species Specific ◽  
Genetically Manipulated

In female mammals, the dosage difference in X-linked genes between XX females and XY males is compensated for by inactivating one of the two X chromosomes during early development. Since the discovery of the X inactive-specific transcript (XIST) gene in humans and its subsequent isolation of the mouse homolog, Xist, in the early 1990s, the molecular basis of X chromosome inactivation (X-inactivation) has been more fully elucidated using genetically manipulated mouse embryos and embryonic stem cells. Studies on X-inactivation in other mammals, although limited when compared with those in the mice, have revealed that, while their inactive X chromosome shares many features with those in the mice, there are marked differences in not only some epigenetic modifications of the inactive X chromosome but also when and how X-inactivation is initiated during early embryonic development. Such differences raise the issue about what extent of the molecular basis of X-inactivation in the mice is commonly shared among others. Recognizing similarities and differences in X-inactivation among mammals may provide further insight into our understanding of not only the evolutionary but also the molecular aspects for the mechanism of X-inactivation. Here, we reviewed species-specific differences in X-inactivation and discussed what these differences may reveal.

scholarly journals Dynamic Relocalization of Histone Macroh2a1 from Centrosomes to Inactive X Chromosomes during X Inactivation

2000 ◽  
Vol 150 (5) ◽  
pp. 1189-1198 ◽  
Author(s):  
Theodore P. Rasmussen ◽  
Mary-Ann Mastrangelo ◽  
Amir Eden ◽  
John R. Pehrson ◽  
Rudolf Jaenisch
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
X Inactivation ◽  
Cell Fractionation ◽  
Histone H2a ◽  
X Chromosomes ◽  
Male And Female ◽  
Terminal Domain ◽  
Xist Rna ◽  
Domain Of Unknown Function

Histone variant macroH2A1 (macroH2A1) contains an NH2-terminal domain that is highly similar to core histone H2A and a larger COOH-terminal domain of unknown function. MacroH2A1 is expressed at similar levels in male and female embryonic stem (ES) cells and adult tissues, but a portion of total macroH2A1 protein localizes to the inactive X chromosomes (Xi) of differentiated female cells in concentrations called macrochromatin bodies. Here, we show that centrosomes of undifferentiated male and female ES cells harbor a substantial store of macroH2A1 as a nonchromatin-associated pool. Greater than 95% of centrosomes from undifferentiated ES cells contain macroH2A1. Cell fractionation experiments confirmed that macroH2A1 resides at a pericentrosomal location in close proximity to the known centrosomal proteins γ-tubulin and Skp1. Retention of macroH2A1 at centrosomes was partially labile in the presence of nocodazole suggesting that intact microtubules are necessary for accumulation of macroH2A1 at centrosomes. Upon differentiation of female ES cells, Xist RNA expression became upregulated and monoallelic as judged by fluorescent in situ hybridization, but early Xist signals lacked associated macroH2A1. Xi acquired macroH2A1 soon thereafter as indicated by the colocalization of Xist RNA and macroH2A1. Accumulation of macroH2A1 on X chromosomes occurred with a corresponding loss of centrosomal macroH2A1. Our results define a sequence for the loading of macroH2A1 on the Xi and place this event in the context of differentiation and Xist expression. Furthermore, these results suggest a role for the centrosome in the X inactivation process.

scholarly journals BRCa1 participates in XIST RNa localization on inactive x chromosome

2019 ◽  
Vol 18 (2) ◽  
pp. 21-26
Author(s):  
E. A. Shestakova ◽  
T. A. Bogush
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Confocal Microscopy ◽  
X Chromosome ◽  
Fluorescent Microscopy ◽  
S Phase ◽  
Immunofluorescent Staining ◽  
Heterochromatin Protein ◽  
Inactive X Chromosome ◽  
Xist Rna

Introduction . Inactive X chromosome (Xi) is associated with noncoding XIST RNA, series of proteins and contains multiple epigenetic modifications that altogether determine a silence of the most of X-linked genes. Recently the data were obtained that tumor suppressor BRCA1 is also associated with Xi. The purpose of this study was to reveal the colocalization of BRCA1 and XIST RNA and precise spatial organization on Xi with the high resolution of confocal microscopy.Materials and methods . The object of the study is IMR90hTERT diploid immortalized fibroblast cell line. For BRCA1 and XIST RNA colocalization analysis on Xi the method of fluorescent hybridization in situ associated with immunofluorescent cell staining (immunoFISH) and confocal microscopy were used. For BRCA1 and heterochromatin protein-1 colocalization study the method of double immunofluorescent staining and common fluorescent microscopy were applied. Results . The study using confocal fluorescent microscopy with higher resolution has demonstrated at first the colocalization of BRCA1 with XIST RNA region of Xi revealed with XIST RNA probes and with replicating Xi and autosomes revealed with BrdU in late S-phase of cell cycle. Altogether, the data obtained suggest the involvement of BRCA1 in the inhibition of gene expression on Xi due to the regulation of XIST RNA association with Xi. Moreover, according to the results of confocal microscopy, BRCA1 also colocalizes with replicating Xi and autosomes revealed with BrdU in late S-phase of cell cycle. This indicates a possible involvement of this protein in the replication of pericentromeric repeats in cellular chromosomes. Colocalization of BRCA1 with heterochromatin protein-1α presented in pericentromeric regions of all chromosomes supports this suggestion.Conclusions . Altogether, the data obtained in this study suggest the involvement of BRCA1 in the inhibition of gene expression on Xi due to the association with noncoding inhibiting XIST RNA and in replication of heterochromatin regions. 

X chromosome retains the memory of its parental origin in murine embryonic stem cells

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 813-821 ◽  
Author(s):  
T. Tada ◽  
M. Tada ◽  
N. Takagi
Keyword(s):  
X Chromosome ◽  
Polar Region ◽  
Biochemical Study ◽  
Es Cells ◽  
Embryonic Stem ◽  
Embryoid Bodies ◽  
Parental Origin ◽  
Visceral Endoderm ◽  
Es Cell ◽  
Preferential Inactivation

A cytogenetic and biochemical study of balloon-like cystic embryoid bodies, formed by newly established embryonic stem (ES) cell lines having a cytogenetically or genetically marked X chromosome, revealed that the paternally derived X chromosome was inactivated in the majority of cells in the yolk sac-like mural region consisting of the visceral endoderm and mesoderm. The nonrandomness was less evident in the more solid polar region containing the ectodermal vesicle, mesoderm and visceral endoderm. Since the same was true in embryoid bodies derived from ES cells at the 30th subculture generation, it was concluded that the imprinting responsible for the preferential inactivation of the paternal X chromosome that was limited to non-epiblast cells of the female mouse embryos, was stably maintained in undifferentiated ES cells. Differentiating epiblast cells should be able to erase or avoid responding to the imprint.

X-chromosome inactivation in XX androgenetic mouse embryos surviving implantation

Development ◽  
2000 ◽  
Vol 127 (19) ◽  
pp. 4137-4145 ◽  
Author(s):  
I. Okamoto ◽  
S. Tan ◽  
N. Takagi
Keyword(s):  
X Chromosome ◽  
Ectopic Expression ◽  
Blastocyst Stage ◽  
X Chromosome Inactivation ◽  
X Inactivation ◽  
Chromosome Inactivation ◽  
Current View ◽  
Replication Banding ◽  
Xist Rna ◽  
Morula Stage

Using genetic and cytogenetic markers, we assessed early development and X-chromosome inactivation (X-inactivation) in XX mouse androgenones produced by pronuclear transfer. Contrary to the current view, XX androgenones are capable of surviving to embryonic day 7.5, achieving basically random X-inactivation in all tissues including those derived from the trophectoderm and primitive endoderm that are characterized by paternal X-activation in fertilized embryos. This finding supports the hypothesis that in fertilized female embryos, the maternal X chromosome remains active until the blastocyst stage because of a rigid imprint that prevents inactivation, whereas the paternal X chromosome is preferentially inactivated in extra-embryonic tissues owing to lack of such imprint. In spite of random X-inactivation in XX androgenones, FISH analyses revealed expression of stable Xist RNA from every X chromosome in XX and XY androgenonetic embryos from the four-cell to morula stage. Although the occurrence of inappropriate X-inactivation was further suggested by the finding that Xist continues ectopic expression in a proportion of cells from XX and XY androgenones at the blastocyst and the early egg cylinder stage, a replication banding study failed to provide positive evidence for inappropriate X-inactivation at E6. 5.

Sign in / Sign up

Export Citation Format

Share Document