title: Overexpression of exportin 5 enhances RNA interference mediated by short hairpin RNAs and microRNAs.
abstract: Plasmids or viral vectors that express short hairpin RNAs (shRNAs) have emerged as important tools for the stable inhibition of specific genes by RNA interference. shRNAs are structural and functional homologs of pre-microRNAs, intermediates in the production of endogenously encoded microRNAs (miRNAs). Therefore, overexpressed shRNAs could inhibit miRNA function by competing for a limiting level of one or more factors involved in miRNA biogenesis or function. Here, we demonstrate that overexpressed shRNAs can saturate the activity of endogenous Exportin 5, a factor required for nuclear export of both shRNAs and pre-miRNAs. While shRNA overexpression can therefore inhibit miRNA function, simultaneous overexpression of Exportin 5 reverses this effect. Moreover, Exportin 5 overexpression can significantly enhance RNA interference mediated by shRNAs. These data have implications for the future clinical utilization of shRNAs and also provide a simple method to enhance RNA interference by shRNAs in culture.
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Box 3025, Room 426 CARL Building, Research Drive, Durham, NC 27710, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Yi
authors.forename: Brian P
authors.initials: BP
authors.lastname: Doehle
authors.forename: Yi
authors.initials: Y
authors.lastname: Qin
authors.forename: Ian G
authors.initials: IG
authors.lastname: Macara
authors.forename: Bryan R
authors.initials: BR
authors.lastname: Cullen
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D015870:Gene Expression; D006801:Humans; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D034622:RNA Interference; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D028884:Karyopherins; D035683:MicroRNAs; C446511:XPO5 protein, human; D020931:ran GTP-Binding Protein