Noncoding RNA and Polycomb recruitment

Abstract

A plethora of noncoding (nc) RNAs has been revealed through the application of high-throughput analysis of the transcriptome, and this has led to an intensive search for possible biological functions attributable to these transcripts. A major category of functional ncRNAs that has emerged is for those that are implicated in coordinate gene silencing, either in cis or in trans. The archetype for this class is the well-studied long ncRNA Xist which functions in cis to bring about transcriptional silencing of an entire X chromosome in female mammals. An important step in X chromosome inactivation is the recruitment of the Polycomb repressive complex PRC2 that mediates histone H3 lysine 27 methylation, a hallmark of the inactive X chromosome, and recent studies have suggested that this occurs as a consequence of PRC2 interacting directly with Xist RNA. Accordingly, other ncRNAs have been linked to PRC2 targeting either in cis or in trans, and here also the mechanism has been proposed to involve direct interaction between PRC2 proteins and the different ncRNAs. In this review, I discuss the evidence for and against this hypothesis, in the process highlighting alternative models and discussing experiments that, in the future, will help to resolve existing discrepancies.

Histone H2A Ubiquitination Inhibits the Enzymatic Activity of H3 Lysine 36 Methyltransferases

“…However, one important and not fully addressed question is the mechanism by which chromatin modifiers set up such modification patterns. Because of the critical role of Polycomb response elements in recruiting the Polycomb group proteins in Drosophila (63,64), and because there are only a few Polycomb response elements identified in mammals (65,66), alternative recruitment mechanisms, such as non-coding RNA-mediated PRC2 recruitment have been proposed and debated (67)(68)(69).…”

Epigenetic regulation in human melanoma: past and future

“…2A). 61 As a consequence of this, the target loci are either activated (Fig. 2B and C) or silenced ( Fig.…”

“…2A) depending on the histone marks. 61 This is the most common mechanism employed by lncRNAs to exercise control over gene regulation. An alternative mode of action involves the binding of regulatory proteins by lncRNAs, thereby inhibiting transcription of protein coding genes (Fig.…”

LncRNA Dum interacts with Dnmts to regulate Dppa2 expression during myogenic differentiation and muscle regeneration

“…Specifically, recent work suggested that a large number of lncRNAs function to epigenetically modulate gene expression through interacting with chromatin modifiers or remodelers. They may act as signals, guides or scaffolds to the chromatin to regulate expression of target genes [2][3][4]. In some cases, the lncRNA and the target genes are transcribed from the same locus or in a very close distance.…”