N 6 -methyladenosine mRNA marking promotes selective translation of regulons required for human erythropoiesis

Many of the regulatory features governing erythrocyte specification, maturation, and associated disorders remain enigmatic. To identify new regulators of erythropoiesis, we utilize a functional genomic screen for genes affecting expression of the erythroid marker CD235a/GYPA. Among validating hits are genes coding for the N6-methyladenosine (m6A) mRNA methyltransferase (MTase) complex, including, METTL14, METTL3, and WTAP. We demonstrate that m6A MTase activity promotes erythroid gene expression programs through selective translation of ~300 m6A marked mRNAs, including those coding for SETD histone methyltransferases, ribosomal components, and polyA RNA binding proteins. Remarkably, loss of m6A marks results in dramatic loss of H3K4me3 marks across key erythroid-specific KLF1 transcriptional targets (e.g., Heme biosynthesis genes). Further, each m6A MTase subunit and a subset of their mRNAs targets are required for human erythroid specification in primary bone-marrow derived progenitors. Thus, m6A mRNA marks promote the translation of a network of genes required for human erythropoiesis. Erythropoiesis can be regulated by transcriptional, epigenetic, and post-transcriptional mechanisms. Here the authors report that N6-methyladenosine mRNA methyltransferase complex stimulates erythropoiesis by promoting translation of specific mRNAs.