RLP AgroScience GmbH; AlPlanta-Institute for Plant Research; Neustadt, Germany.
RNA Biol. 2013 Mar;10(3):453-5. doi: 10.4161/rna.23542. Epub 2013 Jan 16.
RNA-directed DNA methylation (RdDM) involves sequence-specific guiding of the de novo methylation machinery to complementary genomic DNA by RNA molecules. It is still elusive whether guide RNAs bind directly to DNA or to nascent transcripts produced from it. Even the nature of the guide RNAs is not elucidated. RNA interference (RNAi) studies provided a link between RNAi and RdDM indicating that small interfering RNAs (siRNAs) trigger and guide cytosine methylation. The "siRNA hypothesis" is generally accepted. However, recent data demonstrated that RdDM is not always associated with the accumulation of corresponding siRNAs. RdDM triggers may differ from guide RNAs and further studies are needed to clarify if guide RNAs are small or long RNAs, if they are single or double stranded and if they target DNA or nascent transcript.
RNA 指导的 DNA 甲基化 (RdDM) 涉及 RNA 分子将从头甲基化机制引导到互补的基因组 DNA 上的序列特异性。RNA 指导物是直接与 DNA 结合还是与从其产生的新生转录本结合仍不清楚。甚至指导 RNA 的性质也没有阐明。RNA 干扰 (RNAi) 研究为 RNAi 和 RdDM 之间提供了联系,表明小干扰 RNA (siRNA) 触发并指导胞嘧啶甲基化。“siRNA 假说”被普遍接受。然而,最近的数据表明,RdDM 并不总是与相应 siRNA 的积累相关。RdDM 的触发因素可能与指导 RNA 不同,需要进一步研究以澄清指导 RNA 是小 RNA 还是长 RNA,是单链还是双链,以及它们是靶向 DNA 还是新生转录本。