Micromanipulating dosage compensation: understanding X-chromosome inactivation through nuclear transplantation

2003 ◽  
Vol 14 (6) ◽  
pp. 349-358 ◽  
Author(s):  
Kevin Eggan ◽  
Rudolf Jaenisch
Keyword(s):  
X Chromosome ◽  
Dosage Compensation ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Nuclear Transplantation

scholarly journals X-Chromosome Inactivation during Preimplantation Development and in Pluripotent Stem Cells

2020 ◽  
Vol 160 (6) ◽  
pp. 283-294 ◽  
Author(s):  
Paola Rebuzzini ◽  
Maurizio Zuccotti ◽  
Silvia Garagna
Keyword(s):  
Stem Cells ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Pluripotent Stem Cells ◽  
Mammalian Cells ◽  
Gene Dosage ◽  
X Chromosome Inactivation ◽  
Preimplantation Development ◽  
Chromosome Inactivation ◽  
Transcriptional Gene Silencing

X dosage compensation between XX female and XY male mammalian cells is achieved by a process known as X-chromosome inactivation (XCI). XCI initiates early during preimplantation development in female cells, and it is subsequently stably maintained in somatic cells. However, XCI is a reversible process that occurs in vivo in the inner cell mass of the blastocyst, in primordial germ cells or in spermatids during reprogramming. Erasure of transcriptional gene silencing can occur though a mechanism named X-chromosome reactivation (XCR). XCI and XCR have been substantially deciphered in the mouse, whereas they still remain debated in the human. In this review, we summarized the recent advances in the knowledge of X-linked gene dosage compensation during mouse and human preimplantation development and in pluripotent stem cells.

Imprint switching for non-random X-chromosome inactivation during mouse oocyte growth

Development ◽  
2000 ◽  
Vol 127 (14) ◽  
pp. 3101-3105 ◽  
Author(s):  
T. Tada ◽  
Y. Obata ◽  
M. Tada ◽  
Y. Goto ◽  
N. Nakatsuji ◽  
...  
Keyword(s):  
X Chromosome ◽  
Replication Timing ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Nuclear Transplantation ◽  
Chromosome X ◽  
Oocyte Growth ◽  
X Chromosomes ◽  
Embryonic Tissues ◽  
Extraembryonic Tissues

In mammals, X-chromosome inactivation occurs in all female cells, leaving only a single active X chromosome. This serves to equalise the dosage of X-linked genes in male and female cells. In the mouse, the paternally derived X chromosome (X(P)) is imprinted and preferentially inactivated in the extraembryonic tissues whereas in the embryonic tissues inactivation is random. To investigate how X(P) is chosen as an inactivated X chromosome in the extraembryonic cells, we have produced experimental embryos by serial nuclear transplantation from non-growing (ng) oocytes and fully grown (fg) oocytes, in which the X chromosomes are marked with (1) an X-linked lacZ reporter gene to assay X-chromosome activity, or (2) the Rb(X.9)6H translocation as a cytogenetic marker for studying replication timing. In the extraembryonic tissues of these ng/fg embryos, the maternal X chromosome (X(M)) derived from the ng oocyte was preferentially inactivated whereas that from the fg oocyte remained active. However, in the embryonic tissues, X inactivation was random. This suggests that (1) a maternal imprint is set on the X(M) during oocyte growth, (2) the maternal imprint serves to render the X(M) resistant to inactivation in the extraembryonic tissues and (3) the X(M) derived from an ng oocyte resembles a normal X(P).

scholarly journals Regulation of X-chromosome dosage compensation in human: mechanisms and model systems

2017 ◽  
Vol 372 (1733) ◽  
pp. 20160363 ◽  
Author(s):  
Anna Sahakyan ◽  
Kathrin Plath ◽  
Claire Rougeulle
Keyword(s):  
X Chromosome ◽  
Dosage Compensation ◽  
Sex Chromosome ◽  
X Chromosome Inactivation ◽  
Human Cells ◽  
Model Systems ◽  
Chromosome Inactivation ◽  
Embryo Research ◽  
X Chromosomes ◽  
Mary Lyon

The human blastocyst forms 5 days after one of the smallest human cells (the sperm) fertilizes one of the largest human cells (the egg). Depending on the sex-chromosome contribution from the sperm, the resulting embryo will either be female, with two X chromosomes (XX), or male, with an X and a Y chromosome (XY). In early development, one of the major differences between XX female and XY male embryos is the conserved process of X-chromosome inactivation (XCI), which compensates gene expression of the two female X chromosomes to match the dosage of the single X chromosome of males. Most of our understanding of the pre-XCI state and XCI establishment is based on mouse studies, but recent evidence from human pre-implantation embryo research suggests that many of the molecular steps defined in the mouse are not conserved in human. Here, we will discuss recent advances in understanding the control of X-chromosome dosage compensation in early human embryonic development and compare it to that of the mouse. This article is part of the themed issue ‘X-chromosome inactivation: a tribute to Mary Lyon’.

scholarly journals Diverse developmental strategies of X chromosome dosage compensation in eutherian mammals

2019 ◽  
Vol 63 (3-4-5) ◽  
pp. 223-233 ◽  
Author(s):  
Alexander I. Shevchenko ◽  
Elena V. Dementyeva ◽  
Irina S. Zakharova ◽  
Suren M. Zakian
Keyword(s):  
Gene Expression ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Mammalian Species ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Autosomal Gene ◽  
Mammalian Development ◽  
Compensation Mechanisms ◽  
Early Mammalian Development

In eutherian mammals, dosage compensation arose to balance X-linked gene expression between sexes and relatively to autosomal gene expression in the evolution of sex chromosomes. Dosage compensation occurs in early mammalian development and comprises X chromosome upregulation and inactivation that are tightly coordinated epigenetic processes. Despite a uniform principle of dosage compensation, mechanisms of X chromosome inactivation and upregulation demonstrate a significant variability depending on sex, developmental stage, cell type, individual, and mammalian species. The review focuses on relationships between X chromosome inactivation and upregulation in mammalian early development.

scholarly journals X-chromosome dosage compensation dynamics in human early embryos

2020 ◽  
Author(s):  
Kevin Huang ◽  
Qiao Zeng ◽  
Yun Feng ◽  
Youjin Hu ◽  
Qin An ◽  
...  
Keyword(s):  
Single Cell ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Cell Mass ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Preimplantation Embryos ◽  
Human Embryos ◽  
Dosage Balance ◽  
Sister Cells

AbstractIn mammals, female cells are obliged to inactivate one of two X chromosomes to achieve dosage parity with the single X chromosome in male cells, and it is also thought that the single active X chromosome is increased 2-fold to achieve dosage balance with two sets of autosomes (X:A ratio = 1, or Ohno’s hypothesis). However, the ontogeny of X-chromosome inactivation and augmentation of the single active X remains unclear during human embryogenesis. Here, we perform single-cell RNA-seq analysis to examine the timing of X:A balancing and X-inactivation (XCI) in pre- and peri-implantation human embryos up to fourteen days in culture. We find that X-chromosome gene expression in both male and female preimplantation embryos is approximately balanced with autosomes (X:A ratio = 1) after embryonic genome activation (EGA) and persists through fourteen days in vitro. Cross-species analysis of preimplantation embryo also show balanced X:A ratio within the first few days of development. By single-cell mRNA SNP profiling, we find XCI beginning in day 6-7 blastocyst embryos, but does not affect X:A dosage balance. XCI is most evident in trophoectoderm (TE) cells, but can also be observed in a small number of inner cell mass (ICM)-derived cells including primitive endoderm (PE) and epiblast (EPI) cells. Analysis between individual XaXa and XaXi sister cells from the same embryo reveals random XCI and persistently balanced X:A ratio, including sister cells transitioning between XaXa and XaXi states. We therefore conclude that the male X-chromosome undergoes X chromosome augmentation prior to the simultaneous X-chromosome inactivation and augmentation in females. Together, our data demonstrate an evolutionally conserved model of X chromosome dosage compensation in humans and other mammalian species.

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