Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
Bioresource Engineering Division, RIKEN BioResource Research Center, Ibaraki, Japan.
Nat Struct Mol Biol. 2021 Jan;28(1):38-49. doi: 10.1038/s41594-020-00521-1. Epub 2020 Nov 9.
Epigenetic reprogramming of the zygote involves dynamic incorporation of histone variant H3.3. However, the genome-wide distribution and dynamics of H3.3 during early development remain unknown. Here, we delineate the H3.3 landscapes in mouse oocytes and early embryos. We unexpectedly identify a non-canonical H3.3 pattern in mature oocytes and zygotes, in which local enrichment of H3.3 at active chromatin is suppressed and H3.3 is relatively evenly distributed across the genome. Interestingly, although the non-canonical H3.3 pattern forms gradually during oogenesis, it quickly switches to a canonical pattern at the two-cell stage in a transcription-independent and replication-dependent manner. We find that incorporation of H3.1/H3.2 mediated by chromatin assembly factor CAF-1 is a key process for the de novo establishment of the canonical pattern. Our data suggest that the presence of the non-canonical pattern and its timely transition toward a canonical pattern support the developmental program of early embryos.
合子的表观遗传重编程涉及组蛋白变体 H3.3 的动态掺入。然而，H3.3 在早期发育过程中的全基因组分布和动态仍不清楚。在这里，我们描绘了小鼠卵母细胞和早期胚胎中的 H3.3 图谱。我们出人意料地在成熟卵母细胞和受精卵中发现了一种非典型的 H3.3 模式，其中活性染色质处 H3.3 的局部富集受到抑制，H3.3 在整个基因组中相对均匀地分布。有趣的是，尽管非典型 H3.3 模式在卵发生过程中逐渐形成，但它以转录非依赖性和复制依赖性的方式在二细胞阶段迅速切换到典型模式。我们发现，染色质组装因子 CAF-1 介导的 H3.1/H3.2 的掺入是建立典型模式的关键过程。我们的数据表明，非典型模式的存在及其向典型模式的及时转变支持早期胚胎的发育程序。
