The Arabidopsis thaliana Checkpoint Kinase WEE1 Protects against Premature Vascular Differentiation during Replication Stress
The Arabidopsis thaliana Checkpoint Kinase WEE1 Protects against Premature Vascular Differentiation during Replication Stress
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DOI：
10.1105/tpc.110.082768
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发表时间：
2011-04-01
期刊：
影响因子：
11.6
通讯作者：
De Veylder, Lieven
中科院分区：
文献类型：
--
作者：
Cools, Toon;Iantcheva, Anelia;De Veylder, Lieven
固着的生活方式迫使植物对影响其基因组完整性的因素迅速做出反应。因此，植物已经开发出检查点机制，以在DNA胁迫发生时阻止细胞周期进程，从而允许DNA在分裂开始之前被修复。以前，WEE 1激酶已被证明是必不可少的延迟通过细胞周期的复制抑制药物，如羟基脲的存在下进行。为了理解用羟基脲处理的WEE 1缺陷植物的严重生长停滞，进行了转录组学分析，表明S期持续时间延长。WEE 1在S期的作用被证实了其在遭受DNA胁迫的复制细胞核中的特异性积累。除了延长的复制阶段，WEE1敲除植物积累了与过早的维管分化相关的死细胞。相应地，没有功能性WEE 1的植物异位表达维管分化标记VND7，并且它们的维管发育异常。我们的结论是，WEE 1缺陷植物的生长停滞是由于细胞周期的持续时间延长，结合过早发生的维管细胞分化。后者意味着植物WEE 1激酶获得了间接的发育功能，这是重要的分生组织维持复制应力。
A sessile lifestyle forces plants to respond promptly to factors that affect their genomic integrity. Therefore, plants have developed checkpoint mechanisms to arrest cell cycle progression upon the occurrence of DNA stress, allowing the DNA to be repaired before onset of division. Previously, the WEE1 kinase had been demonstrated to be essential for delaying progression through the cell cycle in the presence of replication-inhibitory drugs, such as hydroxyurea. To understand the severe growth arrest of WEE1-deficient plants treated with hydroxyurea, a transcriptomics analysis was performed, indicating prolonged S-phase duration. A role for WEE1 during S phase was substantiated by its specific accumulation in replicating nuclei that suffered from DNA stress. Besides an extended replication phase, WEE1 knockout plants accumulated dead cells that were associated with premature vascular differentiation. Correspondingly, plants without functional WEE1 ectopically expressed the vascular differentiation marker VND7, and their vascular development was aberrant. We conclude that the growth arrest of WEE1-deficient plants is due to an extended cell cycle duration in combination with a premature onset of vascular cell differentiation. The latter implies that the plant WEE1 kinase acquired an indirect developmental function that is important for meristem maintenance upon replication stress.