Structure and function of long noncoding RNAs in epigenetic regulation

Long noncoding RNAs (lncRNAs) fulfill a variety of regulatory roles in gene expression, which are dictated by their RNA structure, chemistry and modular domain structure. In this Review, the focus is on the well-characterized ability for lncRNAs to function as epigenetic modulators as part of a broad epigenetic regulatory network. Genomes of complex organisms encode an abundance and diversity of long noncoding RNAs (lncRNAs) that are expressed throughout the cell and fulfill a wide variety of regulatory roles at almost every stage of gene expression. These roles, which encompass sensory, guiding, scaffolding and allosteric capacities, derive from folded modular domains in lncRNAs. In this diverse functional repertoire, we focus on the well-characterized ability for lncRNAs to function as epigenetic modulators. Many lncRNAs bind to chromatin-modifying proteins and recruit their catalytic activity to specific sites in the genome, thereby modulating chromatin states and impacting gene expression. Considering this regulatory potential in combination with the abundance of lncRNAs suggests that lncRNAs may be part of a broad epigenetic regulatory network.