編者按：這是個(gè)有趣的科學(xué)問(wèn)題。今天出版的Science發(fā)表的文章揭示這個(gè)機(jī)理,。miRNA和siRNA已廣泛應(yīng)用,，但如何從核中進(jìn)入胞漿以發(fā)揮作用？這是值得思考的問(wèn)題,，這篇paper顯示Exp5蛋白可能發(fā)揮關(guān)鍵性作用,。這為miRNA的機(jī)理揭示和應(yīng)用的認(rèn)識(shí)更進(jìn)一步！
Nuclear Export of MicroRNA Precursors
Elsebet Lund,1 Stephan Güttinger,2 Angelo Calado,2* James E. Dahlberg,1 Ulrike Kutay2
Science, Vol. 303, Issue 5654, 95-98, January 2, 2004
MicroRNAs (miRNAs), which function as regulators of gene expression in eukaryotes, are processed from larger transcripts by sequential action of nuclear and cytoplasmic ribonuclease III–like endonucleases. We show that Exportin-5 (Exp5) mediates efficient nuclear export of short miRNA precursors (pre-miRNAs) and that its depletion by RNA interference results in reduced miRNA levels. Exp5 binds correctly processed pre-miRNAs directly and specifically, in a Ran guanosine triphosphate–dependent manner, but interacts only weakly with extended pre-miRNAs that yield incorrect miRNAs when processed by Dicer in vitro. Thus, Exp5 is key to miRNA biogenesis and may help coordinate nuclear and cytoplasmic processing steps.
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