Changes in the nuclear deposition of histone H2A variants during pre-implantation development in mice
Changes in the nuclear deposition of histone H2A variants during pre-implantation development in mice
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DOI：
10.1242/dev.051805
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发表时间：
2010-11-15
期刊：
影响因子：
4.6
通讯作者：
Aoki, Fugaku
中科院分区：
文献类型：
--
作者：
Nashun, Buhe;Yukawa, Masashi;Aoki, Fugaku
组蛋白H2A有几个变异体，与它们的替换相关的染色质组成的变化可能涉及染色质结构的重塑。我们研究了在小鼠卵子发生和植入前发育过程中，当基因组重塑发生时，典型的组蛋白H_2A及其三个变异体H_2A.X、H_2A.Z和宏H_2A的动态。免疫细胞化学结合特异性抗体显示，虽然在成熟卵母细胞的细胞核中有H2A和所有异构体的沉积，但受精后的单细胞胚胎的原核中只有组蛋白H_2A_X富含，而组蛋白H_2A_2和H_2A_Z的丰度很低，没有H_2A_Z。用FLAG表位标记的H_2A、H_2A.Z和大H_2A转基因小鼠证实了受精后H_2A的减少和H_2A_Z和大分子H_2A的耗尽。用编码Flag标记蛋白的mRNA进行的显微注射实验显示，H2A变异体的核掺入模式类似。用H_2A、H_2A.Z和宏H_2A与H_2A_X的C-端23个氨基酸融合的融合蛋白实验表明，H_2A_X的C-端氨基酸在受精后特异性地将这种变异的组蛋白靶向染色质，并且染色质中没有H_2A.Z和宏H_2A是正常发育所必需的。这些结果表明，染色质中组蛋白H_2A变异体组成的整体变化在受精后的基因组重构中发挥了作用。
Histone H2A has several variants, and changes in chromatin composition associated with their replacement might involve chromatin structure remodeling. We examined the dynamics of the canonical histone H2A and its three variants, H2A.X, H2A.Z and macroH2A, in the mouse during oogenesis and pre-implantation development when genome remodeling occurs. Immunocytochemistry with specific antibodies revealed that, although H2A and all variants were deposited in the nuclei of full-grown oocytes, only histone H2A.X was abundant in the pronuclei of one-cell embryos after fertilization, in contrast with the low abundance of histone H2A and the absence of H2A.Z. The decline in H2A and the depletion of H2A.Z and macroH2A after fertilization were confirmed using Flag epitope-tagged H2A, H2A.Z and macroH2A transgenic mouse lines. Microinjection experiments with mRNA encoding the Flag-tagged proteins revealed a similar pattern of nuclear incorporation of the H2A variants. Fusion protein experiments using H2A, H2A.Z and macroH2A fused with the C-terminal 23 amino acids of H2A.X showed that the C-terminal amino acids of H2A.X function specifically to target this variant histone into chromatin in embryos after fertilization and that the absence of H2A.Z and macroH2A from the chromatin is required for normal development. These results suggest that global changes in the composition of histone H2A variants in chromatin play a role in genome remodeling after fertilization.