Departmental Bulletin Paper 〈論文・報告〉化学修飾small interfering RNA (siRNA)による遺伝子サイレンシング

新貝, 恭広  ,  柏原, 慎一  ,  藤井, 啓史  ,  峰松, 剛  ,  吉永, 尚平  ,  苗村, 円佳  ,  神武, 洋二郎  ,  藤井, 政幸

For clinical applications of small interfering RNA (siRNA), chemical structure of siRNA should be optimized to be taken up into cells effectively, resistant to nuclease digestion, incorporated into RNA induced silencing complex (RISC) rapidly and correctly. They should also have minimized off-target effect and maximized turn over number. In this study, we investigated RNA interference (RNAi) efficiencies of siRNAs bearing 5’-amino-5’-deoxythymidine (T*) at 5’-end. The results showed that T* at the 5’-end of the sense strand did not interfere the processes of RISC loading complex (RLC) formation, loading to RISC or cleavage of the passenger strand by human argonaute2 (hAgo2) at all. On the other hand, T* at the 5’-end of the antisense strand gave a fatal damage to siRNA to show almost no silencing effect probably because RISC was destabilized by an electrostatic repulsion between the cationic charge of the ammonium group of T* and the cationic residues in MID domain pocket of hAgo2. These results strongly suggest that a modification of 5’-end of a sense strand with T* will suppress an off-target effect.

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