丹麦哥本哈根大学Anja Groth和英国伦敦医学科学研究所（LMS）Petra Hajkova共同合作，近期取得重要工作进展。他们通过开发利用iDEMS工具，对DNA甲基化和羟甲基化的传播进行定量分析。相关研究成果2023年1月12日在线发表于《自然-细胞生物学》杂志上。

据介绍，DNA甲基化是哺乳动物细胞中重要的表观遗传标记。DNA甲基化维持的许多方面已经被表征，然而，复制后甲基化维持的确切动力学仍然是一个有争论的话题。

研究人员开发了通过5-乙炔基脱氧尿苷标记质谱（iDEMS）分离DNA的方法，这是一种高度灵敏、基于定量质谱的方法，用于测量代谢标记DNA上的DNA修饰。iDEMS揭示了新生DNA上半甲基化概况。将iDEMS与代谢标记相结合表明，小鼠胚胎干细胞中的细胞分裂超过了甲基化维持。他们的方法表明，羟甲基化在姐妹链之间是永久不对称的，而有利于亲本链，模板链。iDEMS可以与染色质蛋白的免疫沉淀相结合，揭示DNA甲基化-组蛋白修饰的相互作用特征，并提示甲基化和核小体组装之间相互作用的模型。

因此，iDEMS阐明了长期以来关于DNA修饰传播问题，并提供了一种重要的正交技术来理解动态细胞环境中的这一过程。

附：英文原文

Title: Quantifying propagation of DNA methylation and hydroxymethylation with iDEMS

Author: Stewart-Morgan, Kathleen R., Requena, Cristina E., Flury, Valentin, Du, Qian, Heckhausen, Zoe, Hajkova, Petra, Groth, Anja

Issue&Volume: 2023-01-12

Abstract: DNA methylation is a critical epigenetic mark in mammalian cells. Many aspects of DNA methylation maintenance have been characterized; however, the exact kinetics of post-replicative methylation maintenance remain a subject of debate. Here we develop isolation of DNA by 5-ethynyl-deoxyuridine labelling for mass spectrometry (iDEMS), a highly sensitive, quantitative mass spectrometry-based method for measuring DNA modifications on metabolically labelled DNA. iDEMS reveals an unexpectedly hemi-methylated landscape on nascent DNA. Combining iDEMS with metabolic labelling reveals that methylation maintenance is outpaced by cell division in mouse embryonic stem cells. Our approach shows that hydroxymethylation is perpetually asymmetric between sister strands in favour of the parental, template strand. iDEMS can be coupled with immunoprecipitation of chromatin proteins, revealing features of DNA methylation–histone modification crosstalk and suggesting a model for interplay between methylation and nucleosome assembly. iDEMS therefore elucidates long-standing questions about DNA modification propagation and provides an important orthogonal technology to understanding this process in dynamic cellular contexts.

DOI: 10.1038/s41556-022-01048-x

Source: https://www.nature.com/articles/s41556-022-01048-x