Abstract Double-stranded RNAs consisting of 21-nucleotide passenger and guide strands, known as small interfering RNAs (siRNAs), can be used for the identification of gene functions and the regulation of genes involved in disease for therapeutics. The difficulty with unmodified siRNAs lies in the chemical synthesis of RNA, its degradation by RNase, the immune response derived from natural RNA, and the off-target effects mediated by the passenger strand. In this study, asymmetrical 18 base-paired double-strand oligonucleotides comprised of alternately combined DNAs and 2′-O-methyl RNAs, denoted as MED-siRNA, were evaluated. These modified oligonucleotides showed high RNase resistance, a reduced immune response, a highly efficient cleavage of target mRNA with binding to Argonaute 2 (Ago2) via RNA interference, and the subsequent reduction of target protein expression. These findings suggest the possibility of alternatives to unmodified siRNAs with potential use in therapeutics.

中文翻译：

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2'-O-甲基RNA和DNA双链寡核苷酸的设计：具有强RNA干扰基因表达抑制活性的天然核苷酸成分

摘要 由 21 个核苷酸的过客链和引导链组成的双链 RNA，称为小干扰 RNA (siRNA)，可用于鉴定基因功能和调控疾病相关基因以进行治疗。未修饰 siRNA 的难点在于 RNA 的化学合成、其被 RNase 降解、源自天然 RNA 的免疫反应以及过客链介导的脱靶效应。在这项研究中，评估了由交替组合的 DNA 和 2'-O-甲基 RNA 组成的不对称 18 碱基配对双链寡核苷酸，表示为 MED-siRNA。这些修饰的寡核苷酸显示出高 RNase 抗性、降低的免疫反应、高效切割靶标 mRNA 并通过 RNA 干扰与 Argonaute 2 (Ago2) 结合，以及随后目标蛋白表达的减少。这些发现表明有可能替代未修饰的 siRNA 并具有潜在的治疗用途。