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Exportin-5 mediates the nuclear export of pre-microRNAs and short hairpin RNAs. Rui Yi, Yi Qin, Ian G. Macara and Bryan R. Cullen Genes & Development (2003) 17:3011-3016 Wan-Ting Chen. Introduction. MicroRNAs (miRNAs): ~22nt noncoding RNAs observed in a wide range of eukaryotes
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Exportin-5 mediates the nuclear export of pre-microRNAs and short hairpin RNAs Rui Yi, Yi Qin, Ian G. Macara and Bryan R. Cullen Genes & Development (2003) 17:3011-3016 Wan-Ting Chen
Introduction • MicroRNAs (miRNAs):~22nt noncoding RNAs observed in a wide range of eukaryotes • Small interference RNAs (siRNAs):endogenous or synthetic short ds RNAs~22nt • Short hairpin RNAs (shRNAs): artificial generated and usally vector-encoded, resembles pre-miRNA in structure • Exportin-5 (Exp5):belongs to karyopherin family, mediates the nuclear export of adenovirus VA1(highly structured 160nt noncoding RNA) Exportin 5?
Materials - plasmids & siRNAs miR-30binds and inhibits the luciferase expression pri-miRNAof miR-30 pre-miRNA of miR-30 ~22nt synthetic miR-30 RNA duplex
Exp5 siRNA inhibits pre-miRNA & shRNA to silence target mRNA • Loss of Exportin-5 expression specifically relieves inhibition of gene expression caused by pre-miRNA or shRNA pri-miRNA shRNA pre-miRNA Synthetic RNA duplex siRNA
Exp5 siRNA results in a decrease in the mature miRNA expression • No accumulation of pre-miRNA intermediate? Analysis of miR-30 RNA expression
Exp5 binds pre-miRNA in the presence of Ran-GTP • Exportin-5 binds pre-miRNA in a Ran-GTP dependent manner Gel-shift analysis
Conclusion and Significance • Exportin-5 is required for nuclear export and biological activity of pre-miRNA and shRNAs, but not for synthetic siRNA function • Exportin-5 can bind pre-miRNAs specifically in vitro, but only in the presence of Ran-GTP • This study identify a major cellular export cargo for Exportin-5 and define a novel cofactor for miRNA biogenesis and function