Strand antagonism in RNAi: an explanation of differences in potency between intracellularly expressed siRNA and shRNA.
Strategies to regulate gene function frequently use small interfering RNAs (siRNAs) that can be made from their shRNA precursors via Dicer. However, when the duplex components of these siRNA effectors are expressed from their respective coding genes, the RNA interference (RNAi) activity is much reduced. Here, we explored the mechanisms of action of shRNA and siRNA and found the expressed siRNA, in contrast to short hairpin RNA (shRNA), exhibits strong strand antagonism, with the sense RNA negatively and unexpectedly regulating RNAi. Therefore, we altered the relative levels of strands of siRNA duplexes during their expression, increasing the level of the antisense component, reducing the level of the sense component, or both and, in this way we were able to enhance the potency of the siRNA. Such vector-delivered siRNA attacked its target effectively. These findings provide new insight into RNAi and, in particular, they demonstrate that strand antagonism is responsible for making siRNA far less potent than shRNA.
State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
Xin
X
Jin
Tingting
T
Sun
Chuanke
C
Zhao
Yongxiang
Y
Zheng
Yufan
Y
Zhang
Weijing
W
Cai
Qiuchen
Q
He
Kaz
K
Taira
Lihe
L
Zhang
Demin
D
Zhou
D021581:Active Transport, Cell Nucleus; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D034622:RNA Interference; D012322:RNA Precursors / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D014161:Transduction, Genetic
D012322:RNA Precursors; D034741:RNA, Small Interfering