Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Welbio Investigator, Université Libre de Bruxelles (ULB), Brussels, Belgium.
CiMUS, Universidade de Santiago de Compostela-Health Research Institute (IDIS), Santiago de Compostela, Coruña, Spain.
Nat Commun. 2020 Oct 2;11(1):4956. doi: 10.1038/s41467-020-18729-6.
Tet-enzyme-mediated 5-hydroxymethylation of cytosines in DNA plays a crucial role in mouse embryonic stem cells (ESCs). In RNA also, 5-hydroxymethylcytosine (5hmC) has recently been evidenced, but its physiological roles are still largely unknown. Here we show the contribution and function of this mark in mouse ESCs and differentiating embryoid bodies. Transcriptome-wide mapping in ESCs reveals hundreds of messenger RNAs marked by 5hmC at sites characterized by a defined unique consensus sequence and particular features. During differentiation a large number of transcripts, including many encoding key pluripotency-related factors (such as Eed and Jarid2), show decreased cytosine hydroxymethylation. Using Tet-knockout ESCs, we find Tet enzymes to be partly responsible for deposition of 5hmC in mRNA. A transcriptome-wide search further reveals mRNA targets to which Tet1 and Tet2 bind, at sites showing a topology similar to that of 5hmC sites. Tet-mediated RNA hydroxymethylation is found to reduce the stability of crucial pluripotency-promoting transcripts. We propose that RNA cytosine 5-hydroxymethylation by Tets is a mark of transcriptome flexibility, inextricably linked to the balance between pluripotency and lineage commitment.
Tet 酶介导的 DNA 中胞嘧啶的 5-羟甲基化在小鼠胚胎干细胞（ESCs）中起着至关重要的作用。在 RNA 中，最近也有证据表明 5-羟甲基胞嘧啶（5hmC）的存在，但它的生理作用在很大程度上仍然未知。在这里，我们展示了这种标记在小鼠 ESCs 和分化的胚状体中的贡献和功能。在 ESCs 中转录组范围的作图揭示了数百种信使 RNA 在由定义明确的独特一致序列和特定特征表征的位点上被 5hmC 标记。在分化过程中，大量的转录物，包括许多编码关键多能性相关因子（如 Eed 和 Jarid2）的转录物，表现出胞嘧啶羟甲基化减少。使用 Tet 基因敲除 ESCs，我们发现 Tet 酶部分负责 mRNA 中 5hmC 的沉积。在转录组范围内的进一步搜索进一步揭示了 Tet1 和 Tet2 结合的 mRNA 靶标，这些靶标显示出与 5hmC 位点相似的拓扑结构。发现 Tet 介导的 RNA 羟甲基化降低了关键多能性促进转录物的稳定性。我们提出，Tets 的 RNA 胞嘧啶 5-羟甲基化是转录组灵活性的标志，与多能性和谱系分化之间的平衡密不可分。
