Two Components of the RNA-Directed DNA Methylation Pathway Associate with MORC6 and Silence Loci Targeted by MORC6 in Arabidopsis.
Two Components of the RNA-Directed DNA Methylation Pathway Associate with MORC6 and Silence Loci Targeted by MORC6 in Arabidopsis.
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DOI：
10.1371/journal.pgen.1006026
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发表时间：
2016-05
期刊：
影响因子：
4.5
通讯作者：
He XJ
中科院分区：
文献类型：
--
作者：
Liu ZW;Zhou JX;Huang HW;Li YQ;Shao CR;Li L;Cai T;Chen S;He XJ
SU（VAR）3-9同源物SUVH 9和双链RNA结合蛋白IDN 2被认为是拟南芥中RNA指导的DNA甲基化（RdDM）途径的组成部分。我们以前发现SUVH 9与MORC 6相互作用，但这种相互作用如何导致转录沉默仍然是难以捉摸的。在这里，我们的遗传分析表明，SUV H2和SUV H9可以在与MORC 6相同的途径中起作用，或者与MORC 6协同作用以介导转录沉默。此外，我们证明，IDN 2与MORC 6相互作用，并介导MORC 6靶基因座的一个子集的沉默。与SUV H2、SUV H9和IDN 2一样，其他RdDM组分（包括Pol IV、Pol V、RDR 2和DRM 2）也是M0 RC 6靶基因座的子集处的转录沉默所需的。MORC 6以前被证明通过异染色质凝聚介导转录沉默。我们证明了SWI/SNF染色质重塑复合物组分SWI 3B、SWI 3C和SWI 3D与MORC 6以及与SUV H9相互作用，然后介导转录沉默。这些结果表明，RdDM组件不仅参与DNA甲基化，但也在MORC 6介导的异染色质凝聚。这项研究说明了DNA甲基化是如何与异染色质凝聚，从而增强在甲基化基因组区域的转录沉默。DNA甲基化是真核生物中转座子沉默和转基因导入所必需的一种保守的表观遗传标记。RNA介导的DNA甲基化途径介导了拟南芥中的DNA从头甲基化，从而导致转录沉默。在这项研究中，我们发现，两个RNA指导的DNA甲基化组件与micrororchidia（MORC）蛋白MORC 6相互作用，并导致转录沉默通过一种机制，这是不同于RNA指导的DNA甲基化途径。先前认为MORC 6通过异染色质凝聚介导转录沉默。我们的研究表明，RNA指导的DNA甲基化组分与MORC 6的相互作用可能介导DNA甲基化和异染色质凝聚之间的联系。
The SU(VAR)3-9 homolog SUVH9 and the double-stranded RNA-binding protein IDN2 were thought to be components of an RNA-directed DNA methylation (RdDM) pathway in Arabidopsis. We previously found that SUVH9 interacts with MORC6 but how the interaction contributes to transcriptional silencing remains elusive. Here, our genetic analysis indicates that SUVH2 and SUVH9 can either act in the same pathway as MORC6 or act synergistically with MORC6 to mediate transcriptional silencing. Moreover, we demonstrate that IDN2 interacts with MORC6 and mediates the silencing of a subset of MORC6 target loci. Like SUVH2, SUVH9, and IDN2, other RdDM components including Pol IV, Pol V, RDR2, and DRM2 are also required for transcriptional silencing at a subset of MORC6 target loci. MORC6 was previously shown to mediate transcriptional silencing through heterochromatin condensation. We demonstrate that the SWI/SNF chromatin-remodeling complex components SWI3B, SWI3C, and SWI3D interact with MORC6 as well as with SUVH9 and then mediate transcriptional silencing. These results suggest that the RdDM components are involved not only in DNA methylation but also in MORC6-mediated heterochromatin condensation. This study illustrates how DNA methylation is linked to heterochromatin condensation and thereby enhances transcriptional silencing at methylated genomic regions. DNA methylation is a conserved epigenetic mark that is required for the silencing of transposons and introduced transgenes in eukaryotes. An RNA-directed DNA methylation pathway mediates de novo DNA methylation and thereby leads to transcriptional silencing in Arabidopsis. In this study, we find that two RNA-directed DNA methylation components interact with the microrchidia (MORC) protein MORC6 and lead to transcriptional silencing through a mechanism that is distinct from the RNA-directed DNA methylation pathway. MORC6 was previously thought to mediate transcriptional silencing through heterochromatin condensation. Our study suggests that the interaction of the RNA-directed DNA methylation components with MORC6 may mediate a link between DNA methylation and heterochromatin condensation.