m6A mRNA methylation is essential for oligodendrocyte maturation and CNS myelination

Oligodendrocytes are responsible for myelin formation and axonal trophic support in the vertebrate CNS. While a number of factors have been discovered that regulate oligodendrocyte lineage progression, the exact molecular mechanisms involved in this process remain unclear. Emerging studies have shown that N6-methyladenosine (m6A), the most common internal RNA modification of mammalian mRNA, plays a critical role in various developmental processes. In this study, we demonstrate that oligodendrocyte lineage progression is accompanied by changes in m6A modification on numerous transcripts. In vivo conditional inactivation in oligodendrocyte lineage cells of an essential m6A writer component, METTL14, results in decreased oligodendrocyte numbers and CNS hypomyelination, although oligodendrocyte precursor cell (OPC) numbers are normal. In vitro Mettl14 ablation disrupts post-mitotic oligodendrocyte maturation. In addition, Mettl14 ablation has distinct effects on OPC and oligodendrocyte transcriptomes. Together, our findings indicate that dynamic RNA methylation plays a critical regulatory role in oligodendrocyte development and CNS myelination. Overall design: Illumina TruSeq stranded mRNA libraries prepared for m6A-seq in three replicates by Illumina HiSseq 4000 platform. Each processed data file was generated from both IP and input samples and is linked to the corresponding IP sample records.