The majority of the mammalian genome is transcribed into long non-coding (lnc) RNAs, transcripts longer than 200 nucleotides and devoid of protein-coding potential. Recent genome-wide mapping efforts led to the identification of thousands novel lncRNAs, but so far only few have been functionally analyzed. Fifteen years ago, our group discovered Airn (antisense to Igf2r RNA non-coding), the first autosomal lncRNA shown to have a silencing function. Airn is an imprinted gene transcribed from the paternal chromosome, in antisense orientation to the imprinted but maternally expressed Igf2r gene. Airn expression controls Igf2r imprinted expression by silencing it in cis on the paternal chromosome, but how Airn exerts its silencing function has long been a mystery. Now, a study published in Science shows that Airn silences Igf2r through transcription alone and not via its RNA product.
- Santoro F, Pauler FM. (2013) Silencing by the imprinted Airn macro lncRNA: Transcription is the answer. Cell Cycle [Epub ahead of print]. [article]