Systematic approaches to identify functional lncRNAs.

Long noncoding RNAs (lncRNAs) were discovered in eukaryotes more than 30 years ago [1]. Recent advances in genomics have led to the discovery that lncRNAs are transcribed pervasively across the genome [2(•),3,4,5(•)]. There are an increasing number of reports that identify lncRNAs whose expression is modulated during cell differentiation or in disease states. However, biological functions for the vast majority of them are yet to be determined. Here, we propose two ways to identify lncRNAs that have biological functions: to identify lncRNAs with dedicated preinitiation complexes (PICs), and to focus on those whose transcription is highly regulated.