RNA-Induced Chromatin Remodeling
RNAs can influence the genes from which they were transcribed by acting as scaffolds that recruit chromatin-modifying factors, which result in gene silencing. Long non-coding RNAs can silence large parts of chromosomes or even an entire X chromosome. Small interfering RNAs, which are typically thought to affect gene expression at the level of mRNA, can sometimes promote heterochromatin formation around their gene. Both classes work in cis, meaning that they appear to silence the copy of the gene from which they were transcribed, not the second copy on the homologous chromosome. Both types of RNAs appear to function by recruiting chromatin-modifying enzymes that modify the histones and/or DNA to form heterochromatin.
In mammals, females have two X chromosomes, while males have one X and one Y chromosome. The X chromosome contains over 1,000 genes. Some of these genes are required for proper...