VAL- and AtBMI1-Mediated H2Aub Initiate the Switch from Embryonic to Postgerminative Growth in Arabidopsis
VAL- and AtBMI1-Mediated H2Aub Initiate the Switch from Embryonic to Postgerminative Growth in Arabidopsis
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DOI：
10.1016/j.cub.2013.05.050
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发表时间：
2013-07
期刊：
影响因子：
9.2
通讯作者：
Chao Yang;Fabian Bratzel;Nora Hohmann;M. Koch;F. Turck;M. Calonje
中科院分区：
文献类型：
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作者：
Chao Yang;Fabian Bratzel;Nora Hohmann;M. Koch;F. Turck;M. Calonje
植物B3结构域转录因子在调节种子发育，特别是种子成熟和萌发中具有重要作用[1]。在B3因子中，AFL（脱落酸不敏感3 [ABI 3]、FUSCA 3 [FUS 3]和叶子叶2 [LEC 2]）蛋白在复杂网络中激活种子成熟程序，而瓦尔（VP 1/ABI 3-LIKE）1/2/3蛋白抑制AFL作用，以通过一种未知机制启动萌发和营养发育[2，3]。此外，AFL基因和叶子叶1（LEC 1）[4]（称为种子成熟基因）在萌发后通过Polycomb组（PcG）机制通过其组蛋白修饰活性（PcG抑制复合物2（PRC 2）的组蛋白H3赖氨酸27三甲基转移酶活性和PRC 1的E3 H2 A单泛素连接酶活性）受到表观遗传学抑制[5-9]。两种组蛋白修饰都是抑制所必需的[7-12];然而，潜在的机制还远不清楚，因为H2 Aub标记的定位和作用仍然未知。在这项工作中，我们证明了瓦尔蛋白和AtBMI 1介导的H2 Aub启动种子成熟基因的阻遏。在初始关闭开关后，通过PRC 2介导的H3 K27 me 3维持阻遏。我们的研究结果表明，种子成熟基因的调控不遵循动物PcG介导的抑制[13]提出的经典分层模型，因为PRC 1活性是这些基因的H3 K27 me 3修饰所必需的。此外，我们显示了不同的机制，以实现PcG镇压在植物中，作为镇压的基因参与其他进程有不同的要求H2 Aub和H3 K27 me 3标记。
Plant B3-domain transcription factors have an important role in regulating seed development, in particular seed maturation and germination [1]. Among the B3 factors, the AFL (ABSCISIC ACID INSENSITIVE3 [ABI3], FUSCA3 [FUS3], and LEAFY COTYLEDON2 [LEC2]) proteins activate the seed maturation program in a complex network, while the VAL (VP1/ABI3-LIKE) 1/2/3 proteins suppress AFL action in order to initiate germination and vegetative development through an as yet unknown mechanism [2, 3]. In addition, theAFLgenes andLEAFY COTYLEDON1(LEC1) [4], referred as seed maturation genes, are epigenetically repressed after germination by the Polycomb group (PcG) machinery via its histone-modifying activities: the histone H3 lysine 27 trimethyltransferase activity of the PcG repressive complex 2 (PRC2) and the E3 H2A monoubiquitin ligase activity of the PRC1 [5–9]. Both histone modifications are required for the repression [7–12]; however, the underlying mechanism is far from clear, because the localization and the role of H2Aub marks are still unknown. In this work, we demonstrate that VAL proteins and AtBMI1-mediated H2Aub initiate repression of seed maturation genes. After the initial off switch, the repression is maintained by PRC2-mediated H3K27me3. Our results indicate that the regulation of seed maturation genes does not follow the classic hierarchical model proposed for animal PcG-mediated repression [13], since the PRC1 activity is required for the H3K27me3 modification of these genes. Furthermore, we show different mechanisms to achieve PcG repression in plants, as the repression of genes involved in other processes has different requirements for H2Aub and H3K27me3 marking.