Trithorax-group proteins ARABIDOPSIS TRITHORAX4 (ATX4) and ATX5 function in abscisic acid and dehydration stress responses
Trithorax-group proteins ARABIDOPSIS TRITHORAX4 (ATX4) and ATX5 function in abscisic acid and dehydration stress responses
复制标题
Trithorax 组蛋白拟南芥 TRITHORAX4 (ATX4) 和 ATX5 在脱落酸和脱水应激反应中发挥作用
DOI：
10.1111/nph.14933
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发表时间：
2018-03-01
期刊：
影响因子：
9.4
通讯作者：
Xu, Zheng-Yi
中科院分区：
文献类型：
--
作者：
Liu, Yutong;Zhang, Ai;Xu, Zheng-Yi
三胸组蛋白（TrxGs）在染色质修饰激活转录中起重要的调节作用。尽管TrxGs广泛参与了发育基因的激活，但其在脱水和脱落酸（阿坝）介导的下游基因表达调控中的功能仍不清楚，本文报道了两个进化上保守的拟南芥TrxGs，ARABIDOPSIS TRITHORAX 4（ATX 4）和ATX 5，在干旱胁迫反应中发挥重要作用。atx 4和atx 5单突变体在种子萌发和幼苗发育过程中表现出耐旱和ABA超敏感的表型，而atx 4和atx 5双突变体表现出进一步加剧的表型。有趣的是，ABA-超敏萌发3（AHG 3），阿坝信号传导的重要负调节因子，在响应阿坝时在ATX 4和ATX 5的遗传下游起作用。ATX 4和ATX 5直接结合AHG 3基因座并使Lys 4的组蛋白H3（H3 K4）三甲基化。此外，ATX 4和ATX 5在AHG 3上的定位在阿坝处理下显著增加，并且也是RNA聚合酶II（RNAP II）定位所必需的。拟南芥TrxGs在脱水胁迫和阿坝响应中的作用
Trithorax-group proteins (TrxGs) play essential regulatory roles in chromatin modification to activate transcription. Although TrxGs have been shown to be extensively involved in the activation of developmental genes, how the specific TrxGs function in the dehydration and abscisic acid (ABA)-mediated modulation of downstream gene expression remains unknown.Here, we report that two evolutionarily conserved Arabidopsis thaliana TrxGs, ARABIDOPSIS TRITHORAX4 (ATX4) and ATX5, play essential roles in the drought stress response. atx4 and atx5 single loss-of-function mutants showed drought stress-tolerant and ABA-hypersensitive phenotypes during seed germination and seedling development, while the atx4 atx5 double mutant displayed further exacerbation of the phenotypes.Genome-wide RNA-sequencing analyses showed that ATX4 and ATX5 regulate the expression of genes functioning in dehydration stress. Intriguingly, ABA-HYPERSENSITIVE GERMINATION 3 (AHG3), an essential negative regulator of ABA signaling, acts genetically downstream of ATX4 and ATX5 in response to ABA. ATX4 and ATX5 directly bind to the AHG3 locus and trimethylate histone H3 of Lys 4 (H3K4). Moreover, ATX4 and ATX5 occupancies at AHG3 are dramatically increased under ABA treatment, and are also essential for RNA polymerase II (RNAPII) occupancies.Our findings reveal novel molecular functions of A. thaliana TrxGs in dehydration stress and ABA responses.