Conventional protein-coding genes account for only a fraction of the RNA transcribed in animal genomes. Many of us grew up thinking that RNAs came in two flavours: those with protein-coding capacity and non-coding RNAs with structural roles, in the form of ribosomal RNAs, tRNAs, snoRNAs, etc. Interest in other forms of long non-coding RNAs (lincRNAs) has been growing over the past decade, building in part on the fact that many lincRNAs are the precursors for micro-RNA biogenesis. In some cases, the miRNA is the only known product of a primary transcript that can be tens of Kb in length. But there is much more to lincRNAs: functions include X inactivation and other forms of chromatin modification (Gupta et al, 2010; Tian et al, 2010), enhancer-like functions regulating transcription (Orom et al, 2010) and regulation of post-transcriptional gene expression by functioning as micro-RNA sponges (Hansen et al, 2013; Memczak et al, 2013). Recent papers from the Couso, Schier and Giraldez/Rajewsky laboratories now bring us full circle, assigning a protein-coding function to lincRNAs (Magny et al, 2013; Pauli et al, 2014), (Bazzini et al, 2014).
- Cohen SM. (2014) Everything old is new again: (linc)RNAs make proteins! EMBO J [Epub ahead of print]. [abstract]