lncRNA definitions and mechanisms

Introduction Approximately three-quarters of the mammalian genome is transcribed into RNA (1–3); however, only a fraction of this transcription produces mRNA, whose mature nucleotide sequence serves as a template for protein synthesis (3). The function of this nonprotein-coding RNA (or noncoding RNA) is mostly obscure, despite a larger number of noncoding genes than protein-coding genes. Given the broad functional repertoire derived from protein-coding RNA, it is perhaps not surprising that the relatively few known functions for noncoding RNAs also span diverse cellular processes, resulting in an array of noncoding RNA subclassifications (4). One particular subclass, long noncoding RNAs (lncRNAs), represents a large family of noncoding RNA molecules with potentially broad implications for basic science, health, and disease. In this Review, we focus on the use of animal models to discover novel lncRNAs and to investigate their significance in vivo.