Nuclear processing and export of microRNAs in Arabidopsis
Nuclear processing and export of microRNAs in Arabidopsis
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DOI：
10.1073/pnas.0405570102
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发表时间：
2005-03-08
影响因子：
11.1
通讯作者：
Poethig, RS
中科院分区：
文献类型：
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作者：
Park, MY;Wu, G;Poethig, RS
在哺乳动物细胞中，核输出受体Exportin 5(Exp5)将前microRNAs(PremiRNAs)和tRNAs输出到细胞质中。在本研究中，我们研究了拟南芥Exp5的同源基因HASTY(HST)在miRNAs和tRNAs的生物发生中的功能。与哺乳动物不同，我们发现miRNAs以单链20-21个核苷酸的分子形式存在于拟南芥的细胞核中。这一观察结果与先前的研究一致，表明参与miRNA生物发生的蛋白质位于拟南芥的细胞核中。虽然miRNAs存在于细胞核中，但大多数聚集在细胞质中。有趣的是，HST功能缺失突变减少了大多数miRNAs的积累，但对tRNAs和内源性小干扰RNA的积累没有影响，也没有影响转基因沉默。相反，tRNA输出受体Exportin-t的同源基因PSD的突变干扰了tRNA-Tyr的加工，但不影响miRNAs的积累或核输出。这些结果表明，HST和PSD在核出口中并不共享RNA货物，这有力地表明，在拟南芥中，这些小RNA存在多种核出口途径。
In mammalian cells, the nuclear export receptor, Exportin 5 (Exp5), exports pre-microRNAs (pre-miRNAs) as well as tRNAs into the cytoplasm. in this study, we examined the function of HASTY (HST), the Arabidopsis ortholog of Exp5, in the biogenesis of miRNAs and tRNAs. In contrast to mammals, we found that miRNAs exist as single-stranded 20- to 21-nt molecules in the nucleus in Arabidopsis. This observation is consistent with previous studies indicating that proteins involved in miRNA biogenesis are located in the nucleus in Arabidopsis. Although miRNAs exist in the nucleus, a majority accumulate in the cytoplasm. Interestingly, loss-of-function mutations in HST reduced the accumulation of most miRNAs but had no effect on the accumulation of tRNAs and endogenous small interfering RNAs, or on transgene silencing. In contrast, a mutation in PAUSED (PSD), the Arabidopsis ortholog of the tRNA export receptor, Exportin-t, interfered with the processing of tRNA-Tyr but did not affect the accumulation or nuclear export of miRNAs. These results demonstrate that HST and PSD do not share RNA cargos in nuclear export and strongly suggest that there are multiple nuclear export pathways for these small RNAs in Arabidopsis.