MBD2 将 DNA 甲基化与雄性配子发生过程中的转座元件沉默相耦合。
MBD2 couples DNA methylation to transposable element silencing during male gametogenesis.
机构信息
Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, USA.
Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, USA.
出版信息
Nat Plants. 2024 Jan;10(1):13-24. doi: 10.1038/s41477-023-01599-3. Epub 2024 Jan 15.
DNA methylation is an essential component of transposable element (TE) silencing, yet the mechanism by which methylation causes transcriptional repression remains poorly understood. Here we study the Arabidopsis thaliana Methyl-CpG Binding Domain (MBD) proteins MBD1, MBD2 and MBD4 and show that MBD2 acts as a TE repressor during male gametogenesis. MBD2 bound chromatin regions containing high levels of CG methylation, and MBD2 was capable of silencing the FWA gene when tethered to its promoter. MBD2 loss caused activation at a small subset of TEs in the vegetative cell of mature pollen without affecting DNA methylation levels, demonstrating that MBD2-mediated silencing acts strictly downstream of DNA methylation. TE activation in mbd2 became more significant in the mbd5 mbd6 and adcp1 mutant backgrounds, suggesting that MBD2 acts redundantly with other silencing pathways to repress TEs. Overall, our study identifies MBD2 as a methyl reader that acts downstream of DNA methylation to silence TEs during male gametogenesis.
DNA 甲基化是转座元件（TE）沉默的一个重要组成部分，但甲基化导致转录抑制的机制仍知之甚少。在这里，我们研究了拟南芥的 Methyl-CpG Binding Domain（MBD）蛋白 MBD1、MBD2 和 MBD4，并表明 MBD2 在雄性配子发生过程中作为 TE 抑制剂发挥作用。MBD2 结合含有高 CG 甲基化水平的染色质区域，并且当 MBD2 被束缚在其启动子时，MBD2 能够沉默 FWA 基因。MBD2 的缺失导致成熟花粉营养细胞中一小部分 TE 的激活，而不影响 DNA 甲基化水平，表明 MBD2 介导的沉默严格作用于 DNA 甲基化的下游。在 mbd5 mbd6 和 adcp1 突变体背景中，mbd2 中的 TE 激活变得更加显著，这表明 MBD2 与其他沉默途径冗余，以抑制 TE。总的来说，我们的研究确定了 MBD2 作为一种甲基读码器，它在雄性配子发生过程中 DNA 甲基化的下游作用来沉默 TE。
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