Study of 5mC-DNA, m6A-RNA and RNA-expression in HeLa, ES and EB [ActinoD in HeLa]. Study of 5mC-DNA, m6A-RNA and RNA-expression in HeLa, ES and EB [ActinoD in HeLa]

Marking of DNA, histones, and RNA is central to gene expression regulation in development and disease. Recent evidence links m6A, installed on RNA by the METTL3-METTL14 methyltransferase complex, to histone modifications, but the link between m6A and DNA methylation remains scarcely explored. This study shows that METTL3-METTL14 recruits the DNA methyltransferase DNMT1 to chromatin for gene-body methylation. We identify a set of genes whose expression is fine-tuned by both gene-body 5mC, which promotes transcription, and m6A, which destabilizes transcripts. We demonstrate that METTL3-METTL14-dependent 5mC and m6A are both essential for the differentiation of embryonic stems cells to embryoid bodies and that the upregulation of key differentiation genes during early differentiation depends on the dynamic balance between increased 5mC and decreased m6A. Our findings add a surprising new dimension to our understanding of how epigenetics and epitranscriptomics combine to regulate gene expression and impact development, most likely among other biological processes. Overall design: Ribodepleted total RNA from HeLa cells wild type and knocked out for METTL3 were analysed for expression levels using RNA-seq technology

DNA、组蛋白与RNA的修饰是发育与疾病进程中基因表达调控的核心环节。近期研究表明，由METTL3-METTL14甲基转移酶复合物（METTL3-METTL14 methyltransferase complex）催化修饰于RNA上的N6-甲基腺嘌呤（m6A）与组蛋白修饰存在关联，但m6A与DNA甲基化之间的联系却鲜有探索。本研究证实，METTL3-METTL14可招募DNA甲基转移酶DNMT1至染色质，介导基因体区域的甲基化修饰。我们鉴定得到一组基因，其表达同时受到基因体5-甲基胞嘧啶（5mC，可促进转录）与m6A（可使转录本不稳定）的精细调控。我们证实，依赖METTL3-METTL14的5mC与m6A，均在胚胎干细胞向拟胚体分化的过程中发挥必需作用；且早期分化阶段关键分化基因的上调，依赖于5mC水平升高与m6A水平降低之间的动态平衡。本研究发现为我们理解表观遗传学与表观转录组学如何协同调控基因表达并影响发育（以及诸多其他生物学过程）增添了令人惊喜的全新维度。实验设计：针对野生型与METTL3基因敲除的HeLa细胞，提取去除核糖体RNA的总RNA，通过RNA测序（RNA-seq）技术分析其基因表达水平。