Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria.
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, New York, NY, USA.
Nat Cell Biol. 2020 Jun;22(6):621-629. doi: 10.1038/s41556-020-0515-y. Epub 2020 May 11.
Epigenetic marks are reprogrammed in the gametes to reset genomic potential in the next generation. In mammals, paternal chromatin is extensively reprogrammed through the global erasure of DNA methylation and the exchange of histones with protamines. Precisely how the paternal epigenome is reprogrammed in flowering plants has remained unclear since DNA is not demethylated and histones are retained in sperm. Here, we describe a multi-layered mechanism by which H3K27me3 is globally lost from histone-based sperm chromatin in Arabidopsis. This mechanism involves the silencing of H3K27me3 writers, activity of H3K27me3 erasers and deposition of a sperm-specific histone, H3.10 (ref. ), which we show is immune to lysine 27 methylation. The loss of H3K27me3 facilitates the transcription of genes essential for spermatogenesis and pre-configures sperm with a chromatin state that forecasts gene expression in the next generation. Thus, plants have evolved a specific mechanism to simultaneously differentiate male gametes and reprogram the paternal epigenome.
表观遗传标记在配子中被重新编程，以在下一世代重置基因组潜力。在哺乳动物中，父本染色质通过 DNA 甲基化的全局擦除和组蛋白与鱼精蛋白的交换而被广泛重新编程。由于 DNA 没有去甲基化并且组蛋白在精子中保留，因此在开花植物中父本表观基因组是如何被重新编程的仍然不清楚。在这里，我们描述了拟南芥中组蛋白基础精子染色质中 H3K27me3 全局丢失的多层次机制。该机制涉及 H3K27me3 写入器的沉默、H3K27me3 擦除器的活性以及精子特异性组蛋白 H3.10（参考文献）的沉积，我们表明 H3.10 对赖氨酸 27 甲基化具有抗性。H3K27me3 的丢失促进了精子发生所必需基因的转录，并预先配置了具有预测下一代基因表达的染色质状态的精子。因此，植物已经进化出一种特定的机制来同时分化雄性配子和重新编程父本表观基因组。
