Requirement of histone acetyltransferases HAM1 and HAM2 for epigenetic modification of FLC in regulating flowering in Arabidopsis
Requirement of histone acetyltransferases HAM1 and HAM2 for epigenetic modification of FLC in regulating flowering in Arabidopsis
复制标题
组蛋白乙酰转移酶 HAM1 和 HAM2 对 FLC 表观遗传修饰调控拟南芥开花的要求
DOI：
10.1016/j.jplph.2012.11.007
复制
发表时间：
2013-03-01
影响因子：
4.3
通讯作者：
Xu, Yunyuan
中科院分区：
文献类型：
--
作者：
Xiao, Jun;Zhang, Hong;Xu, Yunyuan
组蛋白乙酰化是一种与基因激活相关的重要的翻译后修饰。在拟南芥中，两个组蛋白乙酰转移酶HAM1和HAM2在体外重复地作用于乙酰化组蛋白H4赖氨酸5(H4K5ace)。双突变体HAM1/HAM2是致死性的，提示HAM1和HAM2在发育中起着关键作用。在这里，我们使用了一种人工microRNA(AmiRNA)策略来揭示HAM1和HAM2的一个新功能。转amiRNA-HAM1/2基因植株开花早，育性降低。此外，它们对光周期、赤霉酸处理和春化反应正常。在amiRNA-HAM1/2系中，开花抑制基因C(FLC)及其同源基因MADS-box影响开花基因3/4(MAF3/4)的表达降低。HAM1过表达导致花期延迟，PLC和MAF3/4表达增加。PLC突变几乎挽救了HAM1过表达的晚花，这表明HAM1对开花时间的调控依赖于PLC。在amiRNA-HAM1/2细胞中，H4乙酰化水平降低，而在HAM1-OE细胞中，H4乙酰化水平增加，这进一步证实了HAM1在体内的乙酰基转移酶活性。染色质免疫沉淀分析表明，在amiRNA-HAM1/2系中，FLC和MAF3/4处的H4超乙酰化和H4K5ace的含量低于野生型，但在HAM1-OE系中含量较高。因此，HAM1和HAM2可能通过在H4K5乙酰化时对PLC和MAF3/4染色质进行表观遗传修饰来影响开花时间。(C)2012年爱思唯尔股份有限公司。版权所有。
Histone acetylation is an important posttranslational modification associated with gene activation. In Arabidopsis, two MYST histone acetyltransferases HAM1 and HAM2 work redundantly to acetylate histone H4 lysine 5 (H4K5ace) in vitro. The double mutant ham1/ham2 is lethal, which suggests the critical role of HAM1 and HAM2 in development. Here, we used an artificial microRNA (amiRNA) strategy in Arabidopsis to uncover a novel function of HAM1 and HAM2. The amiRNA-HAM1/2 transgenic plants showed early flowering and reduced fertility. In addition, they responded normally to photoperiod, gibberellic acid treatment, and vernalization. The expression of flowering-repressor FLOWERING LOCUS C (FLC) and its homologues, MADS-box Affecting Flowering genes 3/4 (MAF3/4), were decreased in amiRNA-HAM1/2 lines. HAM1 overexpression caused late flowering and elevated expression of PLC and MAF3/4. Mutation of PLC almost rescued the late flowering with HAM1 overexpression, which suggests that HAM1 regulation of flowering time depended on PLC. Global H4 acetylation was decreased in amiRNA-HAM1/2 lines, but increased in HAM1-OE lines, which further confirmed the acetyltransferase activity of HAM1 in vivo. Chromatin immunoprecipitation revealed that H4 hyperacetylation and H4K5ace at FLC and MAF3/4 were less abundant in amiRNA-HAM1/2 lines than the wild type, but were enriched in HAM1-OE lines. Thus, HAM1 and HAM2 may affect flowering time by epigenetic modification of PLC and MAF3/4 chromatins at H4K5 acetylation. (C) 2012 Elsevier GmbH. All rights reserved.