Department of Molecular Biology, Science III, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, 1 rue Michel-Servet, CH-1211 Geneva 4, Switzerland.
Mol Cell. 2022 May 5;82(9):1678-1690.e12. doi: 10.1016/j.molcel.2022.02.034. Epub 2022 Mar 18.
The functional consequence of N-methyladenosine (mA) RNA modification is mediated by "reader" proteins of the YTH family. YTH domain-containing 2 (YTHDC2) is essential for mammalian fertility, but its molecular function is poorly understood. Here, we identify U-rich motifs as binding sites of YTHDC2 on 3' UTRs of mouse testicular RNA targets. Although its YTH domain is an mA-binder in vitro, the YTH point mutant mice are fertile. Significantly, the loss of its 3'→5' RNA helicase activity causes mouse infertility, with the catalytic-dead mutation being dominant negative. Biochemical studies reveal that the weak helicase activity of YTHDC2 is enhanced by its interaction with the 5'→3' exoribonuclease XRN1. Single-cell transcriptomics indicate that Ythdc2 mutant mitotic germ cells transition into meiosis but accumulate a transcriptome with mixed mitotic/meiotic identity that fail to progress further into meiosis. Finally, our demonstration that ythdc2 mutant zebrafish are infertile highlights its conserved role in animal germ cell development.
N6-甲基腺苷（m6A）RNA 修饰的功能后果是由 YTH 家族的“读取器”蛋白介导的。YTH 结构域包含蛋白 2（YTHDC2）对于哺乳动物的生育能力是必不可少的，但它的分子功能知之甚少。在这里，我们确定富含 U 的基序是 YTHDC2 在小鼠睾丸 RNA 靶标 3'UTR 上的结合位点。尽管其 YTH 结构域在体外是 m6A 结合物，但 YTH 点突变小鼠具有生育能力。重要的是，其 3'→5'RNA 解旋酶活性的丧失导致小鼠不育，催化失活突变是显性负突变。生化研究表明，YTHDC2 与 5'→3'外切核酸酶 XRN1 的相互作用增强了其弱解旋酶活性。单细胞转录组学表明，Ythdc2 突变有丝分裂生殖细胞过渡到减数分裂，但积累了具有混合有丝分裂/减数分裂特征的转录组，无法进一步进入减数分裂。最后，我们证明 ythdc2 突变斑马鱼不育，突出了其在动物生殖细胞发育中的保守作用。
