Core Antisense Research, Isis Pharmaceuticals Inc., Carlsbad, CA 92010, USA.
Cell. 2012 Aug 31;150(5):883-94. doi: 10.1016/j.cell.2012.08.014.
The therapeutic utility of siRNAs is limited by the requirement for complex formulations to deliver them to tissues. If potent single-stranded RNAs could be identified, they would provide a simpler path to pharmacological agents. Here, we describe single-stranded siRNAs (ss-siRNAs) that silence gene expression in animals absent lipid formulation. Effective ss-siRNAs were identified by iterative design by determining structure-activity relationships correlating chemically modified single strands and Argonaute 2 (AGO2) activities, potency in cells, nuclease stability, and pharmacokinetics. We find that the passenger strand is not necessary for potent gene silencing. The guide-strand activity requires AGO2, demonstrating action through the RNAi pathway. ss-siRNA action requires a 5' phosphate to achieve activity in vivo, and we developed a metabolically stable 5'-(E)-vinylphosphonate (5'-VP) with conformation and sterioelectronic properties similar to the natural phosphate. Identification of potent ss-siRNAs offers an additional option for RNAi therapeutics and an alternate perspective on RNAi mechanism.
siRNAs 的治疗效用受到将其递送到组织所需的复杂配方的限制。如果能够鉴定出有效的单链 RNA，它们将为药理学药物提供更简单的途径。在这里，我们描述了在没有脂质制剂的情况下沉默动物基因表达的单链 siRNAs（ss-siRNAs）。通过迭代设计确定化学修饰的单链和 Argonaute 2（AGO2）活性、细胞中的效力、核酸酶稳定性和药代动力学之间的结构-活性关系，鉴定出有效的 ss-siRNAs。我们发现过客链对于有效的基因沉默不是必需的。引导链活性需要 AGO2，表明通过 RNAi 途径发挥作用。ss-siRNA 作用需要 5' 磷酸在体内发挥活性，我们开发了一种代谢稳定的 5'-(E)-乙烯基膦酸酯（5'-VP），其构象和立体电子性质与天然磷酸相似。有效 ss-siRNAs 的鉴定为 RNAi 治疗提供了另一种选择，并为 RNAi 机制提供了另一种视角。
