Tag Archives: XIST

Female immune cells use lncRNA to keep their second X chromosome shut off

lncRNA

Autoimmune diseases tend to strike women more than men and having multiple X chromosomes could be the main reason why. While a process called X chromosome inactivation serves to balance out gene dosage between males and females, some genes on the “inactive X” chromosome in immune cells can sometimes escape this process, giving women an extra dose of immunity-related gene ...

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The initiation of imprinted X-chromosome inactivation absolutely requires Xist

lncrna

The long noncoding RNA Xist is expressed from only the paternal X chromosome in mouse preimplantation female embryos and mediates transcriptional silencing of that chromosome. In females, absence of Xist leads to postimplantation lethality. Here, through single-cell RNA sequencing of early preimplantation mouse embryos, PSL Research University scientists found that the initiation of imprinted X-chromosome inactivation absolutely requires Xist. Lack ...

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Visualizing the secondary and tertiary architectural domains of lncRNA RepA

lncRNA

Long noncoding RNAs (lncRNAs) are important for gene expression, but little is known about their structures. RepA is a 1.6-kb mouse lncRNA comprising the same sequence as the 5′ region of Xist, including A and F repeats. It has been proposed to facilitate the initiation and spread of X-chromosome inactivation, although its exact role is poorly understood. To gain insight ...

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Increased expression of long non-coding RNA XIST predicts favorable prognosis of cervical cancer

lncRNA

Researchers from the University of Tokyo to examine the association between the expression of long non‑protein‑coding RNAs (lncRNAs) and clinical prognosis in the pretreatment formalin-fixed, paraffin-embedded (FFPE) tissue samples of cervical squamous cell carcinoma patients that underwent platinum‑based chemoradiation therapy. Between 2001 and 2013, 49 consecutive patients with squamous cell cervical carcinoma were selected for the present study (median follow‑up period, 44.1 months). ...

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Hushing the X Chromosome

lncRNA

Early in the development of female embryos, a crucial event occurs in all cells: An X chromosome is silenced. Whereas males have only one X chromosome, females have two—which means they can have twice as many proteins generated from their X chromosomes. Too much of certain proteins can be lethal, so nature has figured out a way to turn off ...

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“Cat’s Cradling” the 3D Genome by the Act of LncRNA Transcription

lncRNA

There is growing evidence that transcription and nuclear organization are tightly linked. Yet, whether transcription of thousands of long noncoding RNAs (lncRNAs) could play a role in this packaging process remains elusive. Although some lncRNAs have been found to have clear roles in nuclear architecture (e.g., FIRRE, NEAT1, XIST, and others), the vast majority remain poorly understood. In this Perspective, ...

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Long Noncoding RNA: “LNCs” to Cancer

lncRNA

In recent years we have witnessed a paradigm shift concerning the long-lasting controversy over “junk DNA” in the human genome. It is now well established that, besides the roughly 25 000 protein-coding genes, the genome contains tens of thousands of functional elements. In addition, the completion of the ENCODE project—the functional annotation of all regulatory regions of the human genome—has ...

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X-inactivation: xist RNA uses chromosome contacts to coat the X

The mechanisms by which Xist RNA associates with the X chromosome to mediate alterations in chromatin structure remain mysterious. Recent genome-wide Xist RNA distribution studies suggest that this long noncoding RNA uses 3-dimensional chromosome contacts to move to its sites of action. In organisms with XY sex chromosomes, chromatin modifications are directed to the X chromosomes (X) to equalize X-linked ...

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High-resolution Xist binding maps reveal two-step spreading during X-chromosome inactivation

The Xist long noncoding RNA (lncRNA) is essential for X-chromosome inactivation (XCI), the process by which mammals compensate for unequal numbers of sex chromosomes1, 2, 3. During XCI, Xist coats the future inactive X chromosome (Xi)4 and recruits Polycomb repressive complex 2 (PRC2) to the X-inactivation centre (Xic)5. How Xist spreads silencing on a 150-megabases scale is unclear. Here a ...

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Featured long non-coding RNA – XACT

lncRNA

X-chromosome inactivation (XCI) in mammals relies on XIST, a long noncoding transcript that coats and silences the X chromosome in cis. Here researchers from Université Paris Diderot, France report the discovery of a long noncoding RNA, XACT, that is expressed from and coats the active X chromosome specifically in human pluripotent cells. In the absence of XIST, XACT is expressed ...

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