GSE99903
Meg3 non-coding RNA expression controls imprinting by preventing transcriptional up-regulation in cis
Although many long non-coding RNAs (lncRNAs) are controlled by genomic imprinting, their roles often remain unknown. The Dlk1-Dio3 imprinted domain expresses the lncRNA Meg3 (also called Gtl2) and multiple microRNAs and snoRNAs from the maternal chromosome. This locus constitutes an epigenetic model for pluripotency and development, particularly for neurogenesis. The domain's Dlk1 (Delta-like-1) gene encodes a ligand that inhibits Notch1 signalling and regulates diverse developmental processes. Using a hybrid embryonic stem (ES) cell system, we find that Dlk1 becomes imprinted during neural differentiation and that this involves chromatin activation and transcriptional up-regulation on the paternal chromosome. On the maternal chromosome, the Dlk1 gene remains poised. This allelic protection against gene activation is controlled in cis by Meg3 expression and also involves the H3-lysine-27 methyltransferase Ezh2. Maternal Meg3 expression additionally protects against de novo DNA methylation at its promoter. Concordantly, we find that the lncRNA Meg3 is nuclear, accumulates onto the imprinted locus and overlaps in cis with Dlk1 in embryonic cells. Our data evoke an imprinting model in which a mono-allelic lncRNA prevents chromatin and gene activation in cis during development. Overall design: RNA-Seq profiles of NPCs generated from WT ES cells (line BJ-WT3) and 2 different Meg3 KO ES lines (ES lines promoter-/- and intron1-/- derived from ES BJ-WT3) using Illumina HiSeq 2500 as 2 technical replicates.