Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
J Am Chem Soc. 2011 Nov 30;133(47):19153-9. doi: 10.1021/ja206353c. Epub 2011 Nov 8.
RNA-mediated gene regulation and expression are critically dependent on both nucleic acid architecture and recognition. We present a novel mechanism for the regulation of gene expression through direct RNA-RNA interactions between small RNA and mRNA in human cells. Using mRNA reporters containing G-rich sequences in the 5'-untranslated region (5'-UTR), in the coding region, or both, we showed that G-rich small RNAs bind to the reporter mRNAs and form an intermolecular RNA G-quadruplex that can inhibit gene translation in living cells. Using a combination of circular dichroism (CD) and RNase footprinting in vitro, we found that the intermolecular G-quadruplexes show a parallel G-quadruplex structure. We next investigated whether the intermolecular G-quadruplex is present in living cells. Employing the fluorophore-labeled probes, we found that two G-rich RNA molecules form an intermolecular G-quadruplex structure in living cells. These results extend the concept of small RNA-mediated expression and suggest an important role for such RNA structures in the inhibition of mRNA translation.
RNA 介导的基因调控和表达极大地依赖于核酸结构和识别。我们提出了一种新的机制，通过在人类细胞中小 RNA 与 mRNA 之间的直接 RNA-RNA 相互作用来调节基因表达。使用在 5'-非翻译区（5'-UTR）、编码区或两者中含有富含 G 的序列的 mRNA 报告基因，我们表明富含 G 的小 RNA 与报告 mRNA 结合，并形成可以抑制活细胞中基因翻译的分子间 RNA G-四链体。通过体外圆二色性（CD）和 RNase 足迹分析的组合，我们发现分子间 G-四链体呈现平行的 G-四链体结构。接下来，我们研究了分子间 G-四链体是否存在于活细胞中。使用荧光标记的探针，我们发现两个富含 G 的 RNA 分子在活细胞中形成了分子间 G-四链体结构。这些结果扩展了小 RNA 介导的表达概念，并表明这种 RNA 结构在抑制 mRNA 翻译中具有重要作用。
