Exportin 5 is a RanGTP-dependent dsRNA-binding protein that mediates nuclear export of pre-miRNAs
Exportin 5 is a RanGTP-dependent dsRNA-binding protein that mediates nuclear export of pre-miRNAs
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DOI：
10.1261/rna.5167604
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发表时间：
2004-02-01
期刊：
影响因子：
4.5
通讯作者：
Görlich, D
中科院分区：
文献类型：
--
作者：
Bohnsack, MT;Czaplinski, K;Görlich, D
MicroRNAs(MiRNAs)广泛存在于真核生物中，对多种系统的研究表明，miRNAs可以调节特定基因的表达。初级miRNA转录本最初被加工成大约70个核苷酸(NT)的茎环结构(Pre-miRNAs)，输出到细胞质中，进一步加工得到大约22个核苷酸的dsRNAs，最后掺入核糖核蛋白颗粒中，这被认为是活性物种。在这里，我们研究了前miRNAs的核输出，并表明这个过程是饱和的，因此是由载体介导的。出口对核RanGTP的耗尽很敏感，根据这一标准，出口是由RanGTP依赖的出口调节的。一种固定前miRNAs的无偏亲和层析方法确定exportin 5为前miRNA特异的出口载体。我们已经从非洲爪哇克隆了exportin 5，并证明了针对非洲爪哇受体的抗体可以特异性地阻止非洲爪哇卵母细胞细胞核中的前miRNA输出。我们进一步证明Exportin 5以不依赖于序列的方式与双链RNA相互作用。
microRNAs (miRNAs) are widespread among eukaryotes, and studies in several systems have revealed that miRNAs can regulate expression of specific genes. Primary miRNA transcripts are initially processed to approximate to70-nucleotide (nt) stem-loop structures (pre-miRNAs), exported to the cytoplasm, further processed to yield approximate to22-nt dsRNAs, and finally incorporated into ribonucleoprotein particles, which are thought to be the active species. Here we study nuclear export of pre-miRNAs and show that the process is saturable and thus carrier-mediated. Export is sensitive to depletion of nuclear RanGTP and, according to this criterion, mediated by a RanGTP-dependent exportin. An unbiased affinity chromatography approach with immobilized pre-miRNAs identified exportin 5 as the pre-miRNA-specific export carrier. We have cloned exportin 5 from Xenopus and demonstrate that antibodies raised against the Xenopus receptor specifically block pre-miRNA export from nuclei of Xenopus oocytes. We further show that exportin 5 interacts with double-stranded RNA in a sequence-independent manner.