Maize rough sheath2 and its Arabidopsis orthologue ASYMMETRIC LEAVES1 interact with HIRA, a predicted histone chaperone, to maintain knox gene silencing and determinacy during organogenesis
Maize rough sheath2 and its Arabidopsis orthologue ASYMMETRIC LEAVES1 interact with HIRA, a predicted histone chaperone, to maintain knox gene silencing and determinacy during organogenesis
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DOI：
10.1105/tpc.105.035477
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发表时间：
2005-11-01
期刊：
影响因子：
11.6
通讯作者：
Timmermans, MCP
中科院分区：
文献类型：
--
作者：
Phelps-Durr, TL;Thomas, J;Timmermans, MCP
植物芽的特征是不确定的生长，这是由芽顶分生组织（SAM）中干细胞群体的作用引起的。SAM内的不确定性部分由I类Knox同源框基因指定。分别来自玉米（Zea mays）和拟南芥（Arabidopsis thaliana）的myb结构域蛋白粗糙鞘2（RS 2）和不对称叶1（AS 1）是叶发育过程中建立确定性所必需的。这些蛋白质是细胞记忆系统的一部分，在器官形成过程中，细胞记忆系统对干细胞来源的信号做出反应，使knox基因处于关闭状态。在这里，我们表明，RS 2/AS 1可以形成保守的蛋白质复合物，通过与DNA结合因子不对称叶2，预测的RNA结合蛋白（RIK，RS 2相互作用KH蛋白），和同源的染色质重塑蛋白HIRA的相互作用。HIRA功能的部分损失在拟南芥中的结果与as 1的发育缺陷，并导致重新激活的knox基因在发育中的叶子，表明HIRA在knox基因的抑制和叶形成过程中的确定性的建立的直接作用。我们的数据表明，RS 2/AS 1和HIRA介导的knox基因的表观遗传沉默，可能通过调节染色质结构。这一过程的组成部分在动物中是保守的，这表明在植物和动物发育过程中，类似的表观遗传机制可能保持确定性。
Plant shoots are characterized by indeterminate growth resulting from the action of a population of stem cells in the shoot apical meristem (SAM). Indeterminacy within the SAM is specified in part by the class I knox homeobox genes. The myb domain proteins rough sheath2 (RS2) and ASYMMETRIC LEAVES1 (AS1) from maize (Zea mays) and Arabidopsis thaliana, respectively, are required to establish determinacy during leaf development. These proteins are part of a cellular memory system that in response to a stem cell-derived signal keeps knox genes in an off state during organogenesis. Here, we show that RS2/AS1 can form conserved protein complexes through interaction with the DNA binding factor ASYMMETRIC LEAVES2, a predicted RNA binding protein (RIK, for RS2-Interacting KH protein), and a homologue of the chromatin-remodeling protein HIRA. Partial loss of HIRA function in Arabidopsis results in developmental defects comparable to those of as1 and causes reactivation of knox genes in developing leaves, demonstrating a direct role for HIRA in knox gene repression and the establishment of determinacy during leaf formation. Our data suggest that RS2/AS1 and HIRA mediate the epigenetic silencing of knox genes, possibly by modulating chromatin structure. Components of this process are conserved in animals, suggesting the possibility that a similar epigenetic mechanism maintains determinacy during both plant and animal development.