SAC3B, a central component of the mRNA export complex TREX-2, is required for prevention of epigenetic gene silencing in Arabidopsis.
SAC3B, a central component of the mRNA export complex TREX-2, is required for prevention of epigenetic gene silencing in Arabidopsis.
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DOI：
10.1093/nar/gkw850
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发表时间：
2017-01-09
影响因子：
14.9
通讯作者：
Zhu JK
中科院分区：
文献类型：
--
作者：
Yang Y;La H;Tang K;Miki D;Yang L;Wang B;Duan CG;Nie W;Wang X;Wang S;Pan Y;Tran EJ;An L;Zhang H;Zhu JK
表观遗传调控对于生物体的发育和对环境的反应非常重要。表观遗传状态的改变主要是从DNA甲基化和/或组蛋白修饰的酶促作用的角度来了解的。在对参与预防表观遗传沉默的细胞因子的遗传筛选中，我们分离出一个SAC3B突变体缺陷，SAC3B是保守的TREX-2复合体的一个组成部分，将mRNA转录与核胞质输出偶联。拟南芥SAC3B功能障碍导致转基因和内源性基因座的基因沉默，伴随着抑制组蛋白标记H3K9me2的升高和RNA聚合酶Pol II占用的减少。SAC3B功能障碍不会改变转基因d35S::LUC的启动子DNA甲基化水平，尽管DNA去甲基化酶ROS1也是d35S::LUC抗沉默所必需的。THP1和NUA被鉴定为sac3b相关蛋白，其突变也导致d35S::LUC沉默。RNA-DNA杂交存在于被抑制的位点，但与sac3b突变的基因抑制无关。全基因组分析表明，SAC3B在sirna和DNA甲基化的调节中，特别是在一组TAS和TAS样位点上，参与了少量但明确的作用。总之，我们的研究结果不仅揭示了mrna输出因子在转录抗沉默中的关键作用，而且还揭示了SAC3B在塑造植物表观遗传景观中的作用。
Epigenetic regulation is important for organismal development and response to the environment. Alteration in epigenetic status has been known mostly from the perspective of enzymatic actions of DNA methylation and/or histone modifications. In a genetic screen for cellular factors involved in preventing epigenetic silencing, we isolated an Arabidopsis mutant defective in SAC3B, a component of the conserved TREX-2 complex that couples mRNA transcription with nuleo-cytoplasmic export. Arabidopsis SAC3B dysfunction causes gene silencing at transgenic and endogenous loci, accompanied by elevation in the repressive histone mark H3K9me2 and by reduction in RNA polymerase Pol II occupancy. SAC3B dysfunction does not alter promoter DNA methylation level of the transgene d35S::LUC, although the DNA demethylase ROS1 is also required for d35S::LUC anti-silencing. THP1 and NUA were identified as SAC3B-associated proteins whose mutations also caused d35S::LUC silencing. RNA-DNA hybrid exists at the repressed loci but is unrelated to gene suppression by the sac3b mutation. Genome-wide analyses demonstrated minor but clear involvement of SAC3B in regulating siRNAs and DNA methylation, particularly at a group of TAS and TAS-like loci. Together our results revealed not only a critical role of mRNA-export factors in transcriptional anti-silencing but also the contribution of SAC3B in shaping plant epigenetic landscapes.