Department of Molecular, Cell and Developmental Biology, Campus Universidad Autonoma de Madrid, Madrid, Spain.
Epigenetics. 2012 Jan 1;7(1):29-33. doi: 10.4161/epi.7.1.18782.
Cytosine DNA methylation is an epigenetic mark frequently associated with silencing of genes and transposons. In Arabidopsis, the establishment of cytosine DNA methylation is performed by DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2). DRM2 is guided to target sequences by small interfering RNAs (siRNAs) in a pathway termed RNA-directed DNA methylation (RdDM). We performed a screen for mutants that affect the establishment of DNA methylation by investigating genes that contain predicted RNA-interacting domains. After transforming FWA into 429 T-DNA insertion lines, we assayed for mutants that exhibited a late-flowering phenotype due to hypomethylated, thus ectopically expressed, copies of FWA. A T-DNA insertion line within the coding region of the spliceosome gene SR45 (sr45-1) flowered late after FWA transformation. Additionally, sr45-1 mutants display defects in the maintenance of DNA methylation. DNA methylation establishment and maintenance defects present in sr45-1 mutants are enhanced in dcl3-1 mutant background, suggesting a synergistic cooperation between SR45 and DICER-LIKE3 (DCL3) in the RdDM pathway.
胞嘧啶 DNA 甲基化是一种经常与基因和转座子沉默相关的表观遗传标记。在拟南芥中，胞嘧啶 DNA 甲基化的建立是由 DOMAINS REARRANGED METHYLTRANSFERASE 2（DRM2）完成的。DRM2 通过一种称为 RNA 导向的 DNA 甲基化（RdDM）的途径，被小干扰 RNA（siRNA）引导到靶序列。我们通过研究包含预测 RNA 相互作用结构域的基因，进行了影响 DNA 甲基化建立的突变体筛选。在将 FWA 转化为 429 个 T-DNA 插入系后，我们对由于 FWA 的甲基化程度降低、从而异位表达的拷贝而表现出晚花表型的突变体进行了检测。在剪接体基因 SR45 内的一个 T-DNA 插入系（sr45-1）在转化 FWA 后表现出晚花。此外，sr45-1 突变体在 DNA 甲基化的维持方面存在缺陷。sr45-1 突变体中存在的 DNA 甲基化建立和维持缺陷在 dcl3-1 突变体背景中得到增强，这表明 SR45 和 DICER-LIKE3（DCL3）在 RdDM 途径中存在协同合作。
