RNA: Nuclear Glue for Folding the Genome.

A significant amount of RNA is present in the nucleus of mammalian cells but only a small proportion of it is destined for the cytoplasm and subsequent translation, leaving much RNA to associate with chromatin. Historically, nuclear RNA was thought to interact with proteins to form a filamentous nuclear matrix, but this idea became less popular as more dynamic models of chromatin behaviour became more prevalent. Using new molecular and imaging approaches it is becoming clear that RNA should be considered an integral component of nuclear organisation; it is transcriptionally responsive and interacts with abundant nuclear RNA-binding proteins. We suggest that these protein/RNA structures form a dynamic nuclear mesh that can regulate interphase chromatin structure.