Both strands of siRNA have potential to guide posttranscriptional gene silencing in mammalian cells.
Despite the widespread application of RNA interference (RNAi) as a research tool for diverse purposes, the key step of strand selection of siRNAs during the formation of RNA-induced silencing complex (RISC) remains poorly understood. Here, using siRNAs targeted to the complementary region of Survivin and the effector protease receptor 1 (EPR-1), we show that both strands of the siRNA duplex can find their target mRNA and are equally eligible for assembly into Argonaute 2 (Ago2) of RISC in HEK293 cells. Transfection of the synthetic siRNA duplexes with different thermodynamic profiles or short hairpin RNA (shRNA) vectors that generate double-stranded RNAs (dsRNAs), permitting processing specifically from either the 5' or 3' end of the incipient siRNA, results in the degradation of the respective target mRNAs of either strand of the siRNA duplex with comparable efficiencies. Thus, while most RNAi reactions may follow the thermodynamic asymmetry rule in strand selection, our study suggests an exceptional mode for certain siRNAs in which both strands of the duplex are competent in sponsoring RNAi, and implies additional factors that might dictate the RNAi targets.
Wei
Jun-Xia
JX
State Key Laboratory of Cancer Biology; Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, China.
Yang
Jie
J
Sun
Ji-Feng
JF
Jia
Lin-Tao
LT
Zhang
Yong
Y
Zhang
Hui-Zhong
HZ
Li
Xia
X
Meng
Yan-Ling
YL
Yao
Li-Bo
LB
Yang
An-Gang
AG
D060565:Argonaute Proteins; D001483:Base Sequence; D002268:Carboxypeptidases / Q000378:metabolism; D002460:Cell Line; D003562:Cytidine / Q000031:analogs & derivatives; D017931:DNA Primers / Q000235:genetics; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D034622:RNA Interference; D012323:RNA Processing, Post-Transcriptional; D018075:RNA, Complementary / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors / Q000235:genetics; D043244:Ribonuclease III / Q000378:metabolism; D000077022:Survivin; D013816:Thermodynamics; D014529:Uridine / Q000031:analogs & derivatives
C466422:AGO2 protein, human; D060565:Argonaute Proteins; C107489:BIRC5 protein, human; D017931:DNA Primers; D015852:Eukaryotic Initiation Factor-2; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D018075:RNA, Complementary; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; D000077022:Survivin; D003562:Cytidine; D043244:Ribonuclease III; D002268:Carboxypeptidases; C436327:SCPEP1 protein, human; D014529:Uridine