化学修飾によって誘発される構造歪みのsiRMSDパラメータは、siRNAのオフターゲット効果を予測する

We developed siRMSD, a predictive parameter for off-target effects induced by chemical modifications, to optimize siRNA therapeutics. In RNA interference, small interfering RNA (siRNA) suppresses gene function by degrading mRNA with perfect sequence complementarity, providing therapeutic potential through the targeted inhibition of disease-related genes. However, off-target effects on unintended mRNAs pose a significant challenge to clinical application. While chemical modifications improve nuclease stability and reduce off-target effects, the underlying mechanisms remain unclear. Here, we show that structural distortions caused by chemical modifications determine off-target effects. Modifications, including 2'-O-methoxyethyl, 2'-O-methyl, and 2'-formamido, at positions 2-5 disrupted the A-form RNA duplex on argonaute 2, preventing stable binding to target mRNA. In contrast, modifications at positions 6-8 had minimal impact on off-target effect resulting from changes in thermodynamic stability.