《生命科学》 2017, 29(3): 302-309
摘 要：摘 要：DNA 甲基化及去甲基化是生物体调控基因表达的重要机制。在植物中，DNA 甲基化的建立主要通过依赖于小RNA 的甲基化途径来实现，最近的研究发现了DNA 甲基化最初起始的新机制。DNA 主动去甲基化由ROS1/DME 家族介导并通过碱基切除修复的通路来实现。最新的研究发现了ROS1 下游参与碱基切除修复的多个关键因子。更重要的是，越来越多的参与调控DNA 主动去甲基化的特异性的因子及其作用机制被发现。现介绍植物体中DNA 甲基化建立和维持的机制，并着重讨论植物体中DNA 主动去甲基化方向的最新进展。
Abstract: Abstract: DNA methylation and demethylation are important mechanisms regulating gene expression. In Arabidopsis thaliana， the establishment of DNA methylation is achieved by the RNA-directed DNA methylation (RdDM) pathway. Recent studies revealed mechanisms that trigger the initiation of the canonical RdDM pathway. Active DNA demethylation in A. thaliana is mediated by the ROS1 subfamily of 5-methylcytosine-specific DNA glycosylases via the base excision repair mechanism. Recent studies identified key factors that catalyze the downstream steps of active DNA demethylation. More importantly， multiple factors that regulate site-specific targeting of ROS1 were identified. This review summarizes mechanisms of DNA methylation and also discusses recent advances in active DNA demethylation.
