Tag Archives: X chromosome

Researchers use CRISPR to show that the short splicing isoform of Xist RNA is sufficient to induce X-chromosome inactivation

lncRNA

Alternative splicing of mRNA precursors results in multiple protein variants from a single gene and is critical for diverse cellular processes and development. Xist encodes a long noncoding RNA which is a central player to induce X-chromosome inactivation in female mammals and has two major splicing variants: long and short isoforms of Xist RNA. Although a differentiation-specific and a female-specific ...

Read More »

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 ...

Read More »

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 ...

Read More »

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 ...

Read More »

Long Noncoding RNAs in Imprinting and X Chromosome Inactivation

The field of long noncoding RNA (lncRNA) research has been rapidly advancing in recent years. Technological advancements and deep-sequencing of the transcriptome have facilitated the identification of numerous new lncRNAs, many with unusual properties, however, the function of most of these molecules is still largely unknown. Some evidence suggests that several of these lncRNAs may regulate their own transcription in ...

Read More »

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 ...

Read More »

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 ...

Read More »

The Xist lncRNA Exploits Three-Dimensional Genome Architecture to Spread Across the X Chromosome

lncRNA

Mammalian genomes encode thousands of large noncoding RNAs (lncRNAs), many of which regulate gene expression, interact with chromatin regulatory complexes, and are thought to play a role in localizing these complexes to target loci across the genome. A paradigm for this class of lncRNAs is Xist, which orchestrates mammalian X-chromosome inactivation (XCI) by coating and silencing one X chromosome in ...

Read More »

Shedding Light on Unique RNAs

from Bioscience Technology The genes that code for proteins—more than 20,000 in total—make up only about 1 percent of the complete human genome. That entire thing—not just the genes, but also genetic junk and all the rest—is coiled and folded up in any number of ways within the nucleus of each of our cells. Think, then, of the challenge that ...

Read More »

X-Inactivation, Imprinting, and Long Noncoding RNAs in Health and Disease

x chomosome inactivation

X chromosome inactivation and genomic imprinting are classic epigenetic processes that cause disease when not appropriately regulated in mammals. Whereas X chromosome inactivation evolved to solve the problem of gene dosage, the purpose of genomic imprinting remains controversial. Nevertheless, the two phenomena are united by allelic control of large gene clusters, such that only one copy of a gene is ...

Read More »