Combinatorial delivery of small interfering RNAs reduces RNAi efficacy by selective incorporation into RISC.
Despite the great potential of RNAi, ectopic expression of shRNA or siRNAs holds the inherent risk of competition for critical RNAi components, thus altering the regulatory functions of some cellular microRNAs. In addition, specific siRNA sequences can potentially hinder incorporation of other siRNAs when used in a combinatorial approach. We show that both synthetic siRNAs and expressed shRNAs compete against each other and with the endogenous microRNAs for transport and for incorporation into the RNA induced silencing complex (RISC). The same siRNA sequences do not display competition when expressed from a microRNA backbone. We also show that TAR RNA binding protein (TRBP) is one of the sensors for selection and incorporation of the guide sequence of interfering RNAs. These findings reveal that combinatorial siRNA approaches can be problematic and have important implications for the methodology of expression and use of therapeutic interfering RNAs.
Division of Molecular Biology, Beckman Research Institute of the City of Hope, USA.
Daniela
D
Castanotto
Kumi
K
Sakurai
Robert
R
Lingeman
Haitang
H
Li
Louise
L
Shively
Lars
L
Aagaard
Harris
H
Soifer
Anne
A
Gatignol
Arthur
A
Riggs
John J
JJ
Rossi
D002460:Cell Line; D028884:Karyopherins / Q000378:metabolism; D035683:MicroRNAs / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism*; D022661:RNA, Untranslated / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D034743:RNA-Induced Silencing Complex / Q000378:metabolism*; D014162:Transfection; D000099253:Trans-Activation Responsive RNA-Binding Protein
D028884:Karyopherins; D035683:MicroRNAs; D034741:RNA, Small Interfering; D022661:RNA, Untranslated; D016601:RNA-Binding Proteins; D034743:RNA-Induced Silencing Complex; D000099253:Trans-Activation Responsive RNA-Binding Protein