Combinatorial delivery of small interfering RNAs reduces RNAi efficacy by selective incorporation into RISC

Nucleic Acids Res. 2007;35(15):5154-64. doi: 10.1093/nar/gkm543. Epub 2007 Jul 26.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Line
  • Karyopherins / metabolism
  • MicroRNAs / metabolism
  • RNA Interference*
  • RNA, Small Interfering / metabolism*
  • RNA, Untranslated / metabolism
  • RNA-Binding Proteins / metabolism
  • RNA-Induced Silencing Complex / metabolism*
  • Transfection

Substances

  • Karyopherins
  • MicroRNAs
  • RNA, Small Interfering
  • RNA, Untranslated
  • RNA-Binding Proteins
  • RNA-Induced Silencing Complex
  • trans-activation responsive RNA-binding protein