Airn Transcriptional Overlap, But Not Its lncRNA Products, Induces Imprinted Igf2r Silencing

Long Noncoding RNAs The past 5 years have uncovered thousands of long (>100 nucleotides) noncoding RNAs (lncRNAs) outpacing our understanding of their functions and mechanisms in regulating the genome. Lee (p. 1435 ) reviews the known and suspected means by which these intriguing molecules control gene expression locally and at great distances, considers potential universal roles for lncRNAs, and warns that classifying these intriguing molecules may be quite challenging given their diversity. The very long noncoding RNA, Airn , silences the Igf2r (insulin-like growth factor 2 receptor) imprinted gene cluster in mammals. Latos et al. (p. 1469 ) show in mouse cells that, rather than recruiting enzymes that modify histones to repress the locus, it is the act of transcription of Airn (and not the Airn gene product) that results in the silencing.