Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
Nucleic Acid Ther. 2012 Jun;22(3):147-51. doi: 10.1089/nat.2012.0360.
Double-stranded RNAs can target gene promoters and inhibit transcription. To date, most research has focused on synthetic RNA duplexes. Transcriptional silencing by hairpin RNAs would facilitate a better understanding of endogenous RNA-mediated regulation of transcription within cells. Here we examine transcriptional silencing of progesterone receptor (PR) expression by hairpin RNAs. We identify the guide strand as the strand complementary to an antisense transcript at the PR promoter and that hairpin RNAs are active transcriptional silencing agents. The sequence of the hairpin loop affects activity, with the highest activity achieved when the loop has the potential for full complementarity to the antisense transcript target. Introduction of centrally mismatched bases relative to the target transcript does not prevent transcriptional silencing unless the mismatches are present on both the guide and passenger strands. These data demonstrate that hairpin RNAs can cause transcriptional silencing and offer insights into the mechanism of gene modulation by RNAs that target gene promoters.
双链 RNA 可以靶向基因启动子并抑制转录。迄今为止，大多数研究都集中在合成的 RNA 双链体上。发夹 RNA 引起的转录沉默将有助于更好地理解细胞内内源性 RNA 对转录的调节。在这里，我们研究了发夹 RNA 对孕激素受体 (PR) 表达的转录沉默作用。我们确定了向导链，即与 PR 启动子上反义转录本互补的链，并且发夹 RNA 是有效的转录沉默剂。发夹环的序列会影响其活性，当环与反义转录本靶标具有完全互补性时，活性最高。相对于靶转录本，在中心位置引入错配碱基并不会阻止转录沉默，除非这些错配碱基同时存在于向导链和过客链上。这些数据表明发夹 RNA 可以引起转录沉默，并为靶向基因启动子的 RNA 对基因调节的机制提供了新的见解。
