scholarly journals Abnormal X-Chromosome Dosage Compensation as a Possible Cause of Early Developmental Failure in Mice. (X-chromosome inactivation/trophectoderm/imprinting/embryonic development)

1991 ◽  
Vol 33 (5) ◽  
pp. 429-435 ◽  
Author(s):  
Nobuo Takagi
Keyword(s):  
Embryonic Development ◽  
X Chromosome ◽  
Dosage Compensation ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Early Developmental ◽  
Possible Cause

Changes in DNA methylation during mouse embryonic development in relation to X-chromosome activity and imprinting

1990 ◽  
Vol 326 (1235) ◽  
pp. 299-312 ◽  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Embryonic Development ◽  
X Chromosome ◽  
De Novo ◽  
Germ Line ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Chromatin Configuration ◽  
Methylation Patterns

Changing DNA methylation patterns during embryonic development are discussed in relation to differential gene expression, changes in X-chromosome activity and genomic imprinting. Sperm DNA is more methylated than oocyte DNA, both overall and for specific sequences. The methylation difference between the gametes could be one of the mechanisms (along with chromatin structure) regulating initial differences in expression of parental alleles in early development. There is a loss of methylation during development from the morula to the blastocyst and a marked decrease in methylase activity. De novo methylation becomes apparent around the time of implantation and occurs to a lesser extent in extra-embryonic tissue DNA. In embryonic DNA, de novo methylation begins at the time of random X-chromosome inactivation but it continues to occur after X-chromosome inactivation and may be a mechanism that irreversibly fixes specific patterns of gene expression and X-chromosome inactivity in the female. The germ line is probably delineated before extensive de novo methylation and hence escapes this process. The marked undermethylation of the germ line DNA may be a prerequisite for X-chromosome reactivation. The process underlying reactivation and removal of parent-specific patterns of gene expression may be changes in chromatin configuration associated with meiosis and a general reprogramming of the germ line to developmental totipotency.

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.

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 Maternal SMCHD1 controls both imprinted Xist expression and imprinted X chromosome inactivation

2021 ◽  
Author(s):  
Iromi Wanigasuriya ◽  
Sarah A Kinkel ◽  
Tamara Beck ◽  
Ellise A Roper ◽  
Kelsey Breslin ◽  
...  
Keyword(s):  
Embryonic Development ◽  
X Chromosome ◽  
Preimplantation Embryo ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Preimplantation Embryos ◽  
Xist Expression ◽  
Critical Window ◽  
Zygotic Genome

Embryonic development is dependent on the maternal supply of proteins through the oocyte, including factors setting up the adequate epigenetic patterning of the zygotic genome. We previously reported that one such factor is the epigenetic repressor SMCHD1, whose maternal supply controls autosomal imprinted expression in mouse preimplantation embryos and mid-gestation placenta. In mouse preimplantation embryos, X chromosome inactivation is also an imprinted process. Combining genomics and imaging, we show that maternal SMCHD1 is required not only for the imprinted expression of Xist in preimplantation embryos, but also for the efficient silencing of the inactive X in both the preimplantation embryo and mid-gestation placenta. These results expand the role of SMCHD1 in enforcing the silencing of Polycomb targets. The inability of zygotic SMCHD1 to fully restore imprinted X inactivation further points to maternal SMCHD1's role in setting up the appropriate chromatin environment during preimplantation development, a critical window of epigenetic remodelling.

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