N6-methyladenosine RNA modification regulates embryonic neural stem cell self-renewal through histone modifications.

Internal N6-methyladenosine (m6A) modification is widespread in messenger RNAs(mRNAs) and catalyzed by heterodimers of methyltransferase-like protein 3 (Mettl3) andMettl14. To understand the role of m6A in development, we deleted Mettl14 in embryonicneural stem cells (NSCs) in a mouse model. Phenotypically, NSCs lacking Mettl14 displaymarkedly decreased proliferation and premature differentiation, suggesting m6Amodification enhances NSC self-renewal. Decreased NSC pool led to decreased numberlate-born neurons during cortical neurogenesis. Mechanistically, we discovered a genomewide increase in specific histone modifications in Mettl14 knockout vs. control NSCs. Thesechanges correlated with altered gene expression and observed cellular phenotypes,suggesting their functional significance. Finally, we showed that m6A regulates histonemodification in part by destabilizing transcripts encoding histone-modifying enzymes. Ourstudy demonstrated an essential role of m6A in development and revealed m6A-regulatedhistone modifications as a novel gene regulatory mechanism in mammalian cells. We perform high-throughput sequencing of mouse neural progenitor cell (NPC) with or without deletion of Mettl14 to profile RNA expression, m6A methylated RNA profile, H3K27ac, H3K27me3 histone modifications. Each condition (i.e., wiltype, homozygous knockout, heterozygous deletion) is assayed in two or more biological replicates. For the RNA-seq experiments, we performed 3 batches of sequencing experiments in different biological replicates to account for the technical variation