siRNA 脱靶效应的结构引导控制,Journal of the American Chemical Society

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siRNA 脱靶效应的结构引导控制
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2016-07-12 , DOI: 10.1021/jacs.6b06137
Scott R. Suter ₁ , Jessica Sheu-Gruttadauria ₂ , Nicole T. Schirle ₂ , Rachel Valenzuela ₁ , Alexi A. Ball-Jones ₁ , Kazumitsu Onizuka ₁ , Ian J. MacRae ₂ , Peter A. Beal ₁

Affiliation

短干扰 RNA (siRNA) 是利用 RNA 干扰 (RNAi) 途径的有前途的治疗方法，但由于天然 RNA 结构引起的负担需要药物开发进行化学修饰。人类 RNAi 通路组分的结构表征的进展使 siRNA 特性的结构引导优化成为可能。在这里，我们报告了人类 Argonaute 2 (hAgo2) 的 2.3 Å 分辨率晶体结构，它是 RNAi 途径中的一种关键核酸酶，与在位置 1 (g1) 处带有非天然三唑基核苷酸的 siRNA 引导链结合。与天然核苷酸不同，这种类似物深深插入 hAgo2 的中央 RNA 结合裂缝，因此能够调节引导和目标 RNA 之间的配对。hAgo2-siRNA 复合物对仅种子匹配靶标的亲和力因三唑基修饰而显着降低，而对完全匹配靶标的亲和力保持不变。此外，通过修饰降低了 siRNA 对脱靶抑制的效力（IC50 增加了 4 倍），而靶向敲低得到了改善（IC50 降低了 2 倍）。通过将取代基团投射到 g1 的 hAgo2 中央裂隙中来控制 siRNA 靶向与 microRNA (miRNA) 样脱靶效力，是一种具有强大结构原理的增强 siRNA 选择性的新方法。

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Structure-Guided Control of siRNA Off-Target Effects

Short interfering RNAs (siRNAs) are promising therapeutics that make use of the RNA interference (RNAi) pathway, but liabilities arising from the native RNA structure necessitate chemical modification for drug development. Advances in the structural characterization of components of the human RNAi pathway have enabled structure-guided optimization of siRNA properties. Here we report the 2.3 Å resolution crystal structure of human Argonaute 2 (hAgo2), a key nuclease in the RNAi pathway, bound to an siRNA guide strand bearing an unnatural triazolyl nucleotide at position 1 (g1). Unlike natural nucleotides, this analogue inserts deeply into hAgo2's central RNA binding cleft and thus is able to modulate pairing between guide and target RNAs. The affinity of the hAgo2-siRNA complex for a seed-only matched target was significantly reduced by the triazolyl modification, while the affinity for a fully matched target was unchanged. In addition, siRNA potency for off-target repression was reduced (4-fold increase in IC50) by the modification, while on-target knockdown was improved (2-fold reduction in IC50). Controlling siRNA on-target versus microRNA (miRNA)-like off-target potency by projection of substituent groups into the hAgo2 central cleft from g1 is a new approach to enhance siRNA selectivity with a strong structural rationale.

更新日期：2016-07-12

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