Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea.
Department of Agricultural Biotechnology; Research Institute of Agriculture and Life Sciences; and Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826, Korea.
BMB Rep. 2017 Apr;50(4):158-159. doi: 10.5483/bmbrep.2017.50.4.029.
MicroRNAs (miRNAs) regulate gene expression by guiding the Argonaute (Ago)-containing RNA-induced silencing complex (RISC) to specific target mRNA molecules. It is well established that miRNAs are stabilized by Ago proteins, but the molecular features that trigger miRNA destabilization from Ago proteins remain largely unknown. To explore the molecular mechanisms of how targets affect the stability of miRNAs in human Ago (hAgo) proteins, we employed an in vitro system that consisted of a minimal hAgo2-RISC in HEK293T cell lysates. Surprisingly, we found that miRNAs are drastically destabilized by binding to seedless, non-canonical targets. We showed that miRNAs are destabilized at their 3' ends during this process, which is largely attributed to the conformational flexibility of the L1-PAZ domain. Based on these results, we propose that non-canonical targets may play an important regulatory role in controlling the stability of miRNAs, instead of being regulated by miRNAs. [BMB Reports 2017; 50(4): 158-159].
微小 RNA（miRNAs）通过引导 Argonaute（AGO）包含的 RNA 诱导沉默复合物（RISC）到特定的靶 mRNA 分子来调节基因表达。已经证实，miRNAs 被 AGO 蛋白稳定，但触发 AGO 蛋白中 miRNA 不稳定的分子特征在很大程度上仍然未知。为了探索靶标如何影响人 AGO（hAGO）蛋白中 miRNA 稳定性的分子机制，我们利用了由 HEK293T 细胞裂解物中的最小 hAGO2-RISC 组成的体外系统。令人惊讶的是，我们发现 miRNA 与无种子、非典型靶标结合后会严重失稳。我们表明，在此过程中，miRNAs 在其 3' 末端失稳，这主要归因于 L1-PAZ 结构域的构象灵活性。基于这些结果，我们提出非典型靶标可能在控制 miRNA 稳定性方面发挥重要的调节作用，而不是受 miRNA 调节。[BMB 报告 2017；50（4）：158-159]。
