Institute of Molecular Genetics AS CR, Videnska 1083, 14220 Prague 4, Czech Republic.
Nucleic Acids Res. 2012 Jan;40(1):399-413. doi: 10.1093/nar/gkr702. Epub 2011 Sep 8.
Double-stranded RNA (dsRNA) can enter different pathways in mammalian cells, including sequence-specific RNA interference (RNAi), sequence-independent interferon (IFN) response and editing by adenosine deaminases. To study the routing of dsRNA to these pathways in vivo, we used transgenic mice ubiquitously expressing from a strong promoter, an mRNA with a long hairpin in its 3'-UTR. The expressed dsRNA neither caused any developmental defects nor activated the IFN response, which was inducible only at high expression levels in cultured cells. The dsRNA was poorly processed into siRNAs in somatic cells, whereas, robust RNAi effects were found in oocytes, suggesting that somatic cells lack some factor(s) facilitating siRNA biogenesis. Expressed dsRNA did not cause transcriptional silencing in trans. Analysis of RNA editing revealed that a small fraction of long dsRNA is edited. RNA editing neither prevented the cytoplasmic localization nor processing into siRNAs. Thus, a long dsRNA structure is well tolerated in mammalian cells and is mainly causing a robust RNAi response in oocytes.
双链 RNA（dsRNA）可进入哺乳动物细胞中的不同途径，包括序列特异性 RNA 干扰（RNAi）、非序列依赖性干扰素（IFN）反应和腺苷脱氨酶编辑。为了研究 dsRNA 在体内向这些途径的路由，我们使用在强启动子下在体内普遍表达的转基因小鼠，该启动子在其 3'UTR 中具有长发夹的 mRNA。表达的 dsRNA 既不会引起任何发育缺陷，也不会激活 IFN 反应，IFN 反应仅在培养细胞中的高表达水平下才可诱导。dsRNA 在体细胞中被加工成 siRNA 的效率很低，而在卵母细胞中则发现了强大的 RNAi 效应，这表明体细胞缺乏某些促进 siRNA 生物发生的因子。表达的 dsRNA 不会在转染中引起转录沉默。对 RNA 编辑的分析表明，一小部分长 dsRNA 被编辑。RNA 编辑既没有阻止细胞质定位，也没有将其加工成 siRNAs。因此，长 dsRNA 结构在哺乳动物细胞中具有良好的耐受性，主要在卵母细胞中引起强大的 RNAi 反应。
