Yang Dong-Lei, Zhang Guiping, Wang Lili, Li Jingwen, Xu Dachao, Di Cuiru, Tang Kai, Yang Lan, Zeng Liang, Miki Daisuke, Duan Cheng-Guo, Zhang Huiming, Zhu Jian-Kang
1Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Science, Shanghai, 200032 China.
2State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095 China.
Cell Discov. 2018 Oct 16;4:55. doi: 10.1038/s41421-018-0056-8. eCollection 2018.
DNA methylation is a conserved epigenetic mark that is critical for many biological processes in plants and mammals. In Arabidopsis, the antagonistic activities of RNA-directed DNA methylation (RdDM) and ROS1-dependent active DNA demethylation are key for the dynamic regulation of locus-specific DNA methylation. However, the molecular factors that coordinate RdDM and active demethylation are largely unknown. Here we report that CLSY4 and its three paralogous SWI2/SNF2-type chromatin-remodeling proteins function in both RdDM and DNA demethylation in Arabidopsis. We initially identified CLSY4 in a genetic screen for DNA demethylation factors and subsequently demonstrated that it also is important in RdDM. Comprehensive genetic analyses using single and high order mutants of CLSY family proteins revealed their roles as double agents in the balance between methylation and demethylation reactions. The four CLSY proteins collectively are necessary for the canonical RdDM pathway; at the same time, each CLSY likely mediates DNA demethylation at specific loci where DNA methylation depends on RdDM. These results indicate that the four chromatin-remodeling proteins have dual functions in regulating genomic DNA methylation, and thus provide new insights into the dynamic regulation of DNA methylation in a model multicellular eukaryotic organism.
DNA甲基化是一种保守的表观遗传标记，对植物和哺乳动物的许多生物学过程至关重要。在拟南芥中，RNA介导的DNA甲基化（RdDM）和ROS1依赖性活性DNA去甲基化的拮抗作用是位点特异性DNA甲基化动态调控的关键。然而，协调RdDM和活性去甲基化的分子因子在很大程度上尚不清楚。在这里，我们报告CLSY4及其三个同源的SWI2/SNF2型染色质重塑蛋白在拟南芥的RdDM和DNA去甲基化中均发挥作用。我们最初在DNA去甲基化因子的遗传筛选中鉴定出CLSY4，随后证明它在RdDM中也很重要。使用CLSY家族蛋白的单突变体和高阶突变体进行的全面遗传分析揭示了它们在甲基化和去甲基化反应平衡中作为双重作用因子的作用。这四种CLSY蛋白共同对经典的RdDM途径是必需的；同时，每个CLSY可能在特定位点介导DNA去甲基化，在这些位点DNA甲基化依赖于RdDM。这些结果表明，这四种染色质重塑蛋白在调节基因组DNA甲基化方面具有双重功能，从而为模式多细胞真核生物中DNA甲基化的动态调控提供了新的见解。
