Molecular correlates of the murine <i>Xce</i> locus

Avner, Philip; Prissette, Marine; Arnaud, Danielle; Courtier, Béatrice; Cecchi, Chiara; Heard, Edith

doi:10.1017/s0016672398003516

Cited by 26 publications

(14 citation statements)

References 35 publications

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“…In a more recent study, Tsix has been proposed to prevent the recruitment of H3K27 methylation at the Xist locus, as its absence (in a Tsix mutant) results in the appearance of this mark across the Xist locus just prior to Xist up-regulation (Sun et al 2006). Other loci that affect choice include the X-chromosome controlling element (Xce), which leads to skewed patterns of XCI (for review, see Avner et al 1998). This has been genetically mapped 3Ј to Xist, although its exact location and molecular nature remain to be found (Simmler et al 1993;Chadwick et al 2006).…”

Section: Initiation Of X Inactivation: Counting Choice and Cis Inacmentioning

confidence: 99%

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

Heard¹,

Distèche²

2006

Genes Dev.

Self Cite

459

390

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Mammalian females have two X chromosomes and males have only one. This has led to the evolution of special mechanisms of dosage compensation. The inactivation of one X chromosome in females equalizes gene expression between the sexes. This process of X-chromosome inactivation (XCI) is a remarkable example of longrange, monoallelic gene silencing and facultative heterochromatin formation, and the questions surrounding it have fascinated biologists for decades. How does the inactivation of more than a thousand genes on one X chromosome take place while the other X chromosome, present in the same nucleus, remains genetically active? What are the underlying mechanisms that trigger the initial differential treatment of the two X chromosomes? How is this differential treatment maintained once it has been established, and how are some genes able to escape the process? Does the mechanism of X inactivation vary between species and even between lineages? In this review, X inactivation is considered in evolutionary terms, and we discuss recent insights into the epigenetic changes and developmental timing of this process. We also review the discovery and possible implications of a second form of dosage compensation in mammals that deals with the unique, potentially haploinsufficient, status of the X chromosome with respect to autosomal gene expression.In mammals, dosage compensation for X-linked gene products between XX and XY individuals is achieved by silencing one of the two X chromosomes in female cells (Lyon 1961). A second form of dosage compensation maintains a balanced expression between X-linked and autosomal genes by doubling the transcriptional output of the active X. These distinctive regulatory processes derive from the unique evolution of the sex chromosomes. In eutherians, X-chromosome inactivation (XCI) affects the paternal or maternal X chromosome randomly during early development, and the inactive state is then stably inherited, giving rise to adults that are mosaics for two cell types, expressing one or the other X chromosome. The initiation of X inactivation is controlled by the X-inactivation center (Xic), which produces the noncoding Xist transcript responsible for triggering silencing in cis. In marsupials and in the extraembryonic tissues of some placental mammals such as rodents, XCI is imprinted, with the paternal X chromosome (Xp) being inactivated. Imprinted XCI has been proposed to represent the ancestral form of X inactivation. Furthermore, it has been proposed that imprinted XCI may have arisen as a carryover effect from meiotic sex chromosome inactivation (MSCI) in the male germline, a process found in several species that results in silencing of the X and Y chromosomes. We discuss data suggesting that in mice, MSCI may not be essential for imprinted Xp inactivation, raising the possibility that imprinted XCI may have arisen more than once during evolution. We also discuss new insights into the phenomenon of escape from XCI. Although XCI affects most of the X chromosome, several X-linked gene...

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Section: Initiation Of X Inactivation: Counting Choice and Cis Inacmentioning

confidence: 99%

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

Heard¹,

Distèche²

2006

Genes Dev.

Self Cite

459

390

View full text Add to dashboard Cite

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“…The green fluorescent protein (GFP) transgenic line TgN(GFPX)4Nagy (strain D4/XEGFP) on a 129/Sv background (14, 15) was obtained from Dr. David Burke (University of Michigan). To minimize skewing of X inactivation in heterozygous females, the GFP transgene was recombined onto a C57BL/6 X chromosome carrying an Xce b allele (16,17) by backcrossing an F1 hybrid TgN(GFPX)4Nagy ϫ C57BL/6 female to a C57BL/6 male. Female N2 offspring were genotyped for Xce by PCR using the linked microsatellite markers DXPas28 and DXPas29 that distinguish the C57BL/6 Xce b allele from the 129 Xce a allele (16).…”

Section: Micementioning

confidence: 99%

Changes in gene expression associated with loss of function of the NSDHL sterol dehydrogenase in mouse embryonic fibroblasts

Cunningham

Swartzlander

Liyanarachchi

et al. 2005

Journal of Lipid Research

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“…A 20–30% distortion from random inactivation is observed in mice with different alleles of the ‘X controlling element’ or Xce locus [84]. Genetic mapping suggests that the locus lies downstream of Xist [85]; however, the various alleles are correlated with different expression levels of Xist [86] and methylation of the repetitive element forming the CpG island for the Tsix locus [87].…”

Section: Deviations From Random: Females As Mosaicsmentioning

confidence: 99%

The causes and consequences of random and non‐random X chromosome inactivation in humans

2000

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X chromosome (X) inactivation is a remarkable biological process including the choice and cis-limited inactivation of one X, as well as the stable maintenance of this silencing by epigenetic chromatin alterations. The process results in females generally being mosaic for two populations of cells--one with each parental X active. In this review, we discuss recent advances in our understanding of how inactivation works, as well as the causes and clinical implications of deviations from random inactivation.

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Molecular correlates of the murine Xce locus

Cited by 26 publications

References 35 publications

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

Changes in gene expression associated with loss of function of the NSDHL sterol dehydrogenase in mouse embryonic fibroblasts

The causes and consequences of random and non‐random X chromosome inactivation in humans

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