Cell cycle-dependent YTHDF2 promotes mitotic entry by repressing WEE1. Cell cycle-dependent YTHDF2 promotes mitotic entry by repressing WEE1

The m6A modification regulates mRNA stability and translation. Here we show that transcriptomic m6A modification is dynamic and the m6A reader protein YTHDF2 promotes mRNA decay during the cell cycle. Depletion of YTHDF2 leads to the delay of mitotic entry due to overaccumulation of WEE1, a negative regulator of CDK1. We demonstrate that WEE1 transcripts contain m6A modification, which promotes their decay through the m6A reader YTHDF2. Moreover, we found that YTHDF2 protein stability is dependent on CDK1 activity. Thus, CDK1, YTHDF2, and WEE1 form a feedforward regulatory loop to promote mitotic entry. We further identified CUL1, CUL4A, DDB1, and SKP2 as components of E3 ubiquitin ligase complexes that mediate YTHDF2 proteolysis. Our study provides insights into how cell cycle mediators modulate transcriptomic m6A modification, which in turn regulates the cell cycle. Overall design: Illumina TruSeq stranded mRNA libraries prepared for m6A-seq, RIP-seq and RNA-seq in two replicates by Illumina HiSseq 4000 platform.

N6-甲基腺嘌呤（m6A）修饰可调控mRNA的稳定性与翻译过程。本研究证实，转录组层面的m6A修饰具有动态特性，且m6A阅读蛋白YTHDF2可在细胞周期进程中促进mRNA降解。敲低YTHDF2会因细胞周期蛋白依赖性激酶1（CDK1）的负调控因子WEE1的过度积累，导致有丝分裂进入延迟。本研究证实，WEE1转录本携带m6A修饰，该修饰可通过m6A阅读蛋白YTHDF2促进其降解。此外，本研究发现YTHDF2蛋白的稳定性依赖于CDK1的活性。由此可见，CDK1、YTHDF2与WEE1可形成前馈调控环路，以促进有丝分裂进入。本研究进一步鉴定出CUL1、CUL4A、DDB1与SKP2为介导YTHDF2蛋白水解的E3泛素连接酶复合物组分。本研究为解析细胞周期调控因子如何调控转录组m6A修饰、进而反向调控细胞周期提供了新的研究视角。整体实验设计：借助Illumina HiSeq 4000平台，为m6A测序（m6A-seq）、RNA免疫沉淀测序（RIP-seq）与RNA测序（RNA-seq）构建Illumina TruSeq链特异性mRNA文库，并设置两次生物学重复。