Mette M F, Aufsatz W, van der Winden J, Matzke M A, Matzke A J
Institute of Molecular Biology, Austrian Academy of Sciences, Billrothstrasse 11, A-5020 Salzburg, Austria.
EMBO J. 2000 Oct 2;19(19):5194-201. doi: 10.1093/emboj/19.19.5194.
Double-stranded RNA induces a post-transcriptional gene silencing process, termed RNAi, in diverse organisms. It is shown here that transcriptional gene silencing accompanied by de novo methylation of a target promoter in plants can be triggered by a double-stranded RNA containing promoter sequences. Similar to the double-stranded RNA involved in RNAi, this promoter double-stranded RNA, which is synthesized in the nucleus, is partially cleaved into small RNAs approximately 23 nucleotides in length. Both transcriptional and post-transcriptional gene silencing can thus be initiated by double-stranded RNAs that enter the same degradation pathway. The results also implicate double-stranded RNA in directing DNA methylation. Different constructs designed to produce double-stranded promoter RNA in various ways were evaluated for their ability to induce gene silencing in tobacco and Arabidopsis. RNA hairpins transcribed from inverted DNA repeats were the most effective trans-acting silencing signals. This strategy could be useful for transcriptionally downregulating genes in a variety of plants.
双链RNA在多种生物体中诱导一种转录后基因沉默过程，称为RNA干扰（RNAi）。本文表明，在植物中，包含启动子序列的双链RNA可引发与靶启动子从头甲基化相伴的转录基因沉默。与参与RNAi的双链RNA相似，这种在细胞核中合成的启动子双链RNA被部分切割成长度约为23个核苷酸的小RNA。因此，转录和转录后基因沉默都可由进入相同降解途径的双链RNA引发。这些结果还表明双链RNA参与指导DNA甲基化。对以各种方式设计产生双链启动子RNA的不同构建体在烟草和拟南芥中诱导基因沉默的能力进行了评估。从反向DNA重复序列转录的RNA发夹是最有效的反式作用沉默信号。该策略对于在多种植物中转录下调基因可能有用。
