Plant secondary siRNA production determined by microRNA-duplex structure
Plant secondary siRNA production determined by microRNA-duplex structure
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DOI：
10.1073/pnas.1200169109
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发表时间：
2012-02-14
影响因子：
11.1
通讯作者：
Weigel, Detlef
中科院分区：
文献类型：
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作者：
Manavella, Pablo A.;Koenig, Daniel;Weigel, Detlef
microRNA （miRNA）前体的加工导致双链miRNA/miRNA*双链的释放。miRNA或引导链被装载到Argonaute （AGO）效应体上，miRNA*或乘客链通常被降解。负载ago -含rna诱导的沉默复合物特异性识别靶mRNA，导致其降解或翻译抑制。在植物中，mirna介导的靶标切割在某些情况下会触发次级小干扰rna （sirna）的产生，sirna反过来可以沉默其他基因。这种替代途径取决于miRNA的长度和效应复合体中特定的AGO。然而，22-nt mirna在该途径中是足够的，但不是必需的。通过计算和实验相结合的方法，我们发现当小RNA未在ago2中保留22 nt长时，可触发传递性。此外，我们证明了在miRNA: miRNA*双链中不对称定位的凸起碱基，无论miRNA或miRNA*长度如何，都足以启动传递性。我们认为rna诱导的沉默复合体重编程发生在miRNA装载的早期阶段，在miRNA双链被分解和引导链被选择之前。
Processing of microRNA (miRNA) precursors results in the release of a double-stranded miRNA/miRNA* duplex. The miRNA or guide strand, is loaded onto the Argonaute (AGO) effector, and the miRNA* or passenger strand is typically degraded. The loaded AGO-containing RNA-induced silencing complex specifically recognizes a target mRNA, leading to its degradation or translational inhibition. In plants, miRNA-mediated cleavage of a target triggers in some cases the production of secondary small interfering RNAs (siRNAs), which in turn can silence other genes in trans. This alternative pathway depends on the length of the miRNA and the specific AGO in the effector complex. However, 22-nt miRNAs are sufficient, but not essential for this pathway. Using a combination of computational and experimental approaches, we show that transitivity can be triggered when the small RNA that is not retained in AGOis 22-nt long. Moreover, we demonstrate that asymmetrically positioned bulged bases in the miRNA: miRNA* duplex, regardless of miRNA or miRNA* length, are sufficient for the initiation of transitivity. We propose that the RNA-induced silencing complex reprogramming occurs during the early steps of miRNA loading, before the miRNA duplex is disassembled and the guide strand is selected.