Vernal ization-induced trimethylation of histone H3 lysine 27 at FLC is not maintainedin mitotically quiescent cells
Vernal ization-induced trimethylation of histone H3 lysine 27 at FLC is not maintainedin mitotically quiescent cells
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DOI：
10.1016/j.cub.2007.10.026
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发表时间：
2007-11-20
期刊：
影响因子：
9.2
通讯作者：
Dennis, Elizabeth S.
中科院分区：
文献类型：
--
作者：
Finnegan, E. Jean;Dennis, Elizabeth S.
春化作用通过表观遗传抑制开花基因FLC促进拟南芥开花[1-3]。春化，像其他多晶体介导的抑制事件[4]一样，发生在两个阶段；flrepression在低温下建立，然后在随后的22℃生长过程中保持[5,6]。低温诱导VIN3活性，这是组蛋白修饰变化和相关FLC抑制[3]所必需的。植物多梳蛋白FIE、VRN2、CLF和SWIN与VIN3一起形成一个复合物，在春化植物的FLC上增加组蛋白H3赖氨酸27的甲基化[2,3,7]。VRN1和LHP1是维持FLC抑制所必需的[2,3,6,8]。在低温处理过程中，组织必须进行细胞分裂才能加速开花[9,10]。我们发现低温处理可以抑制非有丝分裂活性细胞中的FLC，但这种抑制不能完全维持。三甲基赖氨酸27 (K27me3)，在寒冷期间在FLC基因的开始富集，然后在春化后扩散到整个位点。在没有DNA复制的情况下，K27me3在FLC开始时被添加到染色质上，但在返回22℃时被移除。这表明DNA复制对于维持春化诱导的FLC抑制至关重要。
Vernalization promotes flowering in Arabidopsis through epigenetic repression of the floral repressor, FLOWERING LOCUS C (FLC) [1-3]. Vernalization, like other polycomb-mediated repression events [4], occurs in two stages; FLCrepression is established at low temperatures, then maintained during subsequent growth at 22 degrees C [5, 6]. Low temperatures induce VIN3 activity, which is required for changes in histone modifications and the associated FLC repression [3]. Plant polycomb proteins FIE, VRN2, CLF, and SWIN, together with VIN3, form a complex that adds histone H3 lysine 27 methylation at FLC in vernalized plants [2,3,7]. VRN1 and LHP1 are required for maintenance of FLC repression [2, 3, 6, 8]. Tissue must be undergoing cell division during lowtemperature treatments for acceleration of flowering to occur [9, 10]. We show that low-temperature treatments repress FLC in cells that are not mitotically active, but this repression is notfully maintained. Trimethyl-lysine 27 (K27me3), is enriched at the start of the FLC gene during the cold, before spreading across the locus after vernalization. In the absence of DNA replication, K27me3 is added to chromatin at the start of FLC but is removed on return to 22 degrees C. This suggests that DNA replication is essential for maintenance of vernalization-induced repression of FLC.