Circular non-coding RNAs are found to play important roles in biology but are still relatively unexplored as a structural motif for chemically regulating gene function. Here, we investigated whether small interfering RNA (siRNA) with a circular structure can circumvent off-target gene silencing, a problem often observed with standard linear duplex siRNA. In the present work, we, for the first time, synthesized a series of circular siRNAs by cyclizing two ends of a single-stranded RNA (sense or antisense strand) to construct circular siRNAs that were more resistant to enzymatic degradation. Gene silencing of GFP and luciferase was successfully achieved using these circular siRNAs with circular sense strand RNAs and their complementary linear antisense strand RNAs. The off-target effect of sense strand RNAs was evaluated and no cross off-target effects were observed. In addition, we successfully achieved longer gene-silencing efficiency in mice with circular siRNAs than with linear siRNAs. These results indicate the promise of circular siRNAs for overcoming off-target effects of siRNAs and enhancing the possible long-term effect of siRNA gene silencing in basic research and drug development.

已发现环状非编码RNA在生物学中起着重要作用，但作为化学调节基因功能的结构基序，目前仍相对未被探索。在这里，我们研究了具有圆形结构的小干扰RNA（siRNA）是否可以规避脱靶基因沉默，这是标准线性双链siRNA经常观察到的问题。在本工作中，我们首次通过环化单链RNA（有义或反义链）的两个末端来构建一系列环状siRNA，以构建对酶促降解更具抵抗力的环状siRNA。使用这些带有环状有义链RNA及其互补的线性反义链RNA的环状siRNA，可以成功实现GFP和荧光素酶的基因沉默。评估有义链RNA的脱靶效应，未观察到交叉脱靶效应。此外，与线性siRNA相比，我们在具有圆形siRNA的小鼠中成功实现了更长的基因沉默效率。这些结果表明，环状siRNA有望克服siRNA的脱靶作用，并在基础研究和药物开发中增强siRNA基因沉默的可能的长期作用。