Linker histone variants control chromatin dynamics during early embryogenesis
Linker histone variants control chromatin dynamics during early embryogenesis
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DOI：
10.1073/pnas.0409824102
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发表时间：
2005-04-19
影响因子：
11.1
通讯作者：
Kaneda, Y
中科院分区：
文献类型：
--
作者：
Saeki, H;Ohsumi, K;Kaneda, Y
在后生动物的发育过程中，染色质结构的复杂转变导致基因组功能的变化。连接组蛋白是核小体组装成染色质的最后一个组分，与核心组蛋白相比，其包括相当不同的亚型。在所有的后生动物研究中，它们的组成在早期胚胎发生过程中伴随合子基因的激活发生了显着变化，导致了至今仍知之甚少的明显功能变化。在这里，我们表明，早期胚胎接头组蛋白B4，这是母系表达，是功能不同的体细胞组蛋白H1在影响染色质结构和动力学。我们建立了一个以核小体组装蛋白-1为连接蛋白的染色质组装系统。该分析系统揭示，母体组蛋白B4允许染色质被ATP依赖性染色质重塑因子重塑，而体细胞组蛋白H1阻止这种重塑。结构分析表明，组蛋白B4并没有显着限制连接DNA的可及性。这些发现定义了连接体组蛋白变体发育变化的功能意义。我们提出了一个模型，认为母体表达的连接组蛋白是关键分子指定核动力学方面的胚胎全能性。
Complex transitions in chromatin structure produce changes in genome function during development in metazoa. Linker histones, the last component of nucleosomes to be assembled into chromatin, comprise considerably divergent subtypes as compared with core histones. In all metazoa studied, their composition changes dramatically during early embryogenesis concomitant with zygotic gene activation, leading to distinct functional changes that are still poorly understood. Here, we show that early embryonic linker histone B4, which is maternally expressed, is functionally different from somatic histone H1 in influencing chromatin structure and dynamics. We developed a chromatin assembly system with nucleosome assembly protein-1 as a linker histone chaperone. This assay system revealed that maternal histone B4 allows chromatin to be remodeled by ATP-dependent chromatin remodeling factor, whereas somatic histone H1 prevents this remodeling. Structural analysis shows that histone B4 does not significantly restrict the accessibility of linker DNA. These findings define the functional significance of developmental changes in linker histone variants. We propose a model that holds that maternally expressed linker histones are key molecules specifying nuclear dynamics with respect to embryonic totipotency.