By means of RNA interference (RNAi), small interfering RNAs (siRNAs) play important roles in gene function study and drug development. Recently, photolabile siRNAs were developed to elucidate the process of gene silencing in terms of space, time and degree through chemical modification of siRNAs. We report herein a novel type of photolabile siRNA that was synthesized through cyclizing two ends of a single stranded RNA with a photocleavable linker. These circular siRNAs became more resistant to serum degradation. Using reporter assays of firefly/Renilla luciferase and GFP/RFP, the gene silencing activities of caged circular siRNAs for both genes were evaluated in HEK293 cells. The results indicated that the target genes were successfully photomodulated using these caged circular siRNAs that were formed by caged circular antisense guide RNAs and their linear complementary sense RNAs. Using the caged circular siRNA targeting GFP, we also successfully achieved photomodulation of GFP expression in mice. Upon further optimization, this new type of caged circular siRNA is expected to be a promising tool for studying gene therapy.

中文翻译：

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笼状环状siRNA用于光调制细胞和小鼠中的基因表达

借助于RNA干扰（RNAi），小的干扰RNA（siRNA）在基因功能研究和药物开发中起着重要作用。近来，开发了对光不稳定的siRNA，以通过化学修饰siRNA在空间，时间和程度方面阐明基因沉默的过程。我们在这里报告了一种新型的光不稳定siRNA，它是通过用光可裂解的接头环化单链RNA的两个末端而合成的。这些环状siRNA对血清降解更具抵抗力。使用萤火虫/雷尼利亚的报告基因检测荧光素酶和GFP / RFP，在HEK293细胞中评估了笼状环状siRNA对这两个基因的基因沉默活性。结果表明，使用由笼状环状反义引导RNA及其线性互补有义RNA形成的笼状环状siRNA，成功地对靶基因进行了光调制。使用靶向GFP的笼状环状siRNA，我们还成功地实现了小鼠中GFP表达的光调节。经过进一步优化后，这种新型的笼状环状siRNA有望成为研究基因疗法的有前途的工具。