Vernalization requires epigenetic silencing of FLC by histone methylation
Vernalization requires epigenetic silencing of FLC by histone methylation
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DOI：
10.1038/nature02269
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发表时间：
2004-01-08
期刊：
影响因子：
64.8
通讯作者：
Dean, C
中科院分区：
文献类型：
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作者：
Bastow, R;Mylne, JS;Dean, C
为了确保在有利的条件下开花，许多植物只有在较长的寒冷时期后才开花，即冬季。在拟南芥中，长时间的寒冷加速了开花，这一过程称为春化，涉及到FLC蛋白的下调，否则将阻止开花(1，2)。这种降低的FLC表达通过VRN基因(3，4)的活性在随后的发育过程中保持。VRN1编码一种DNA结合蛋白(4)，而VRN2编码一种多梳蛋白的同源物，这种蛋白在动物发育过程中维持基因的沉默(3)。在这里，我们表明春化引起组蛋白甲基化的变化，在FLC基因座内的离散区域，增加了组蛋白H3上赖氨酸9和27的二甲基化。这样的修饰识别果蝇和人类细胞中沉默的染色质状态(5-7)。H3K27的二甲基化仅在vrn2突变体中缺失，但H3K9的二甲基化在vrn1和vrn2中均缺失，这与VRN1在VRN2下游的功能一致。因此，冬天的表观遗传记忆是由一种“组蛋白密码”调节的，这种密码指定了动物和植物之间保守的一种沉默的染色质状态。
To ensure flowering in favourable conditions, many plants flower only after an extended period of cold, namely winter. In Arabidopsis, the acceleration of flowering by prolonged cold, a process called vernalization, involves downregulation of the protein FLC, which would otherwise prevent flowering(1,2). This lowered FLC expression is maintained through subsequent development by the activity of VERNALIZATION (VRN) genes(3,4). VRN1 encodes a DNA-binding protein(4) whereas VRN2 encodes a homologue of one of the Polycomb group proteins, which maintain the silencing of genes during animal development(3). Here we show that vernalization causes changes in histone methylation in discrete domains within the FLC locus, increasing dimethylation of lysines 9 and 27 on histone H3. Such modifications identify silenced chromatin states in Drosophila and human cells(5-7). Dimethylation of H3 K27 was lost only in vrn2 mutants, but dimethylation of H3 K9 was absent from both vrn1 and vrn2, consistent with VRN1 functioning downstream of VRN2. The epigenetic memory of winter is thus mediated by a 'histone code' that specifies a silent chromatin state conserved between animals and plants.