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.

Regulation of imprinted X-chromosome inactivation in mice by Tsix

Development ◽  
2001 ◽  
Vol 128 (8) ◽  
pp. 1275-1286 ◽  
Author(s):  
T. Sado ◽  
Z. Wang ◽  
H. Sasaki ◽  
E. Li
Keyword(s):  
X Chromosome ◽  
X Chromosome Inactivation ◽  
X Inactivation ◽  
Chromosome Inactivation ◽  
Maternal Allele ◽  
Xist Expression ◽  
Developmental Defects ◽  
X Chromosomes ◽  
Embryonic Tissues ◽  
Early Embryonic Lethality

In mammals, X-chromosome inactivation is imprinted in the extra-embryonic lineages with paternal X chromosome being preferentially inactivated. In this study, we investigate the role of Tsix, the antisense transcript from the Xist locus, in regulation of Xist expression and X-inactivation. We show that Tsix is transcribed from two putative promoters and its transcripts are processed. Expression of Tsix is first detected in blastocysts and is imprinted with only the maternal allele transcribed. The imprinted expression of Tsix persists in the extra-embryonic tissues after implantation, but is erased in embryonic tissues. To investigate the function of Tsix in X-inactivation, we disrupted Tsix by insertion of an IRES(β)geo cassette in the second exon, which blocked transcripts from both promoters. While disruption of the paternal Tsix allele has no adverse effects on embryonic development, inheritance of a disrupted maternal allele results in ectopic Xist expression and early embryonic lethality, owing to inactivation of both X chromosomes in females and single X chromosome in males. Further, early developmental defects of female embryos with maternal transmission of Tsix mutation can be rescued by paternal inheritance of the Xist deletion. These results provide genetic evidence that Tsix plays a crucial role in maintaining Xist silencing in cis and in regulation of imprinted X-inactivation in the extra-embryonic tissues.

scholarly journals Maternally expressed NLRP2 links the subcortical maternal complex (SCMC) to fertility, embryogenesis and epigenetic reprogramming

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Sangeetha Mahadevan ◽  
Varsha Sathappan ◽  
Budi Utama ◽  
Isabel Lorenzo ◽  
Khalied Kaskar ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Embryonic Development ◽  
Subcellular Localization ◽  
Crucial Role ◽  
Preimplantation Embryos ◽  
Maternal Genome ◽  
Embryonic Loss ◽  
Cytoplasmic Complex ◽  
Zygotic Genome

Abstract Mammalian parental genomes contribute differently to early embryonic development. Before activation of the zygotic genome, the maternal genome provides all transcripts and proteins required for the transition from a highly specialized oocyte to a pluripotent embryo. Depletion of these maternally-encoded transcripts frequently results in failure of preimplantation embryonic development, but their functions in this process are incompletely understood. We found that female mice lacking NLRP2 are subfertile because of early embryonic loss and the production of fewer offspring that have a wide array of developmental phenotypes and abnormal DNA methylation at imprinted loci. By demonstrating that NLRP2 is a member of the subcortical maternal complex (SCMC), an essential cytoplasmic complex in oocytes and preimplantation embryos with poorly understood function, we identified imprinted postzygotic DNA methylation maintenance, likely by directing subcellular localization of proteins involved in this process, such as DNMT1, as a new crucial role of the SCMC for mammalian reproduction.

Getting to the center of X-chromosome inactivation: the role of transgenesThis paper is one of a selection of papers published in this Special Issue, entitled 30th Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2009 ◽  
Vol 87 (5) ◽  
pp. 759-766 ◽  
Author(s):  
Jakub Minks ◽  
Carolyn J. Brown
Keyword(s):  
X Chromosome ◽  
Peer Review Process ◽  
Regulatory Elements ◽  
X Chromosome Inactivation ◽  
X Inactivation ◽  
Chromosome Inactivation ◽  
Xist Expression ◽  
Inactivation Center ◽  
Xist Rna ◽  
Epigenetic Phenomenon

X-chromosome inactivation is a fascinating epigenetic phenomenon that is initiated by expression of a noncoding (nc)RNA, XIST, and results in transcriptional silencing of 1 female X. The process requires a series of events that begins even before XIST expression, and culminates in an active and a silent X within the same nucleus. We will focus on the role that transgenic systems have served in the current understanding of the process of X-chromosome inactivation, both in the initial delineation of an active and inactive X, and in the function of the XIST RNA. X inactivation is strictly cis-limited; recent studies have revealed elements within the X-inactivation center, the region required for inactivation, that are critical for the initial regulation of Xist expression and chromosome pairing. It has been revealed that the X-inactivation center contains a remarkable compendium of cis-regulatory elements, ncRNAs, and trans-acting pairing regions. We review the functional componentry of the X-inactivation center and discuss experiments that helped to dissect the XIST/Xist RNA and its involvement in the establishment of facultative heterochromatin.

scholarly journals Do LINEs Have a Role in X-Chromosome Inactivation?

2006 ◽  
Vol 2006 ◽  
pp. 1-6 ◽  
Author(s):  
Mary F. Lyon
Keyword(s):  
X Chromosome ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Current Evidence ◽  
X Chromosomes ◽  
Repeat Elements ◽  
Sequencing Project ◽  
Human Genome Sequencing ◽  
Human And Mouse

There is longstanding evidence that X-chromosome inactivation (XCI) travels less successfully in autosomal than in X-chromosomal chromatin. The interspersed repeat elements LINE1s (L1s) have been suggested as candidates for “boosters” which promote the spread of XCI in the X-chromosome. The present paper reviews the current evidence concerning the possible role of L1s in XCI. Recent evidence, accruing from the human genome sequencing project and other sources, confirms that mammalian X-chromosomes are indeed rich in L1s, except in regions where there are many genes escaping XCI. The density of L1s is the highest in the evolutionarily oldest regions. Recent work on X; autosome translocations in human and mouse suggested failure of stabilization of XCI in autosomal material, so that genes are reactivated, but resistance of autosomal genes to the original silencing is not excluded. The accumulation of L1s on the X-chromosome may have resulted from reduced recombination or late replication. Whether L1s are part of the mechanism of XCI or a result of it remains enigmatic.

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 DNA metylation as one of the main mechanisms of gene activity regulation

2004 ◽  
Vol 2 (1) ◽  
pp. 27-37
Author(s):  
Anna A Pendina ◽  
Vera V Grinkevich ◽  
Tatyana V Kuznetsova ◽  
Vladislav S Baranov
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
X Chromosome ◽  
Epigenetic Inheritance ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Gene Repression ◽  
Activity Regulation ◽  
Inherited Diseases

 DNA methylation is one of the main mechanisms of epigenetic inheritance in eukaryotes. In this review we looked through the ways of 5-methylcytosin origin, it's distribution in genome, the mechanism of gene repression via hypermetilation, the role of metylation in genomic imprinting and in X-chromosome inactivation, in embryogenesis of mammals, in the processes of oncogenesis and in etiology of some common human inherited diseases

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