The nuclear RNase III Drosha initiates microRNA processing
The nuclear RNase III Drosha initiates microRNA processing
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DOI：
10.1038/nature01957
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发表时间：
2003-09-25
期刊：
影响因子：
64.8
通讯作者：
Kim, VN
中科院分区：
文献类型：
--
作者：
Lee, Y;Ahn, C;Kim, VN
最近在动物和植物中发现了数百种与22个核苷酸相似的小rna，统称为microrna (miRNAs)（1-10）。虽然它们的功能正在被揭示（1,2,11-13），但它们的生物发生机制仍然知之甚少。mirna被转录为长初级转录本（pri- mirna），其成熟通过一系列加工事件发生：将pri- mirna核加工成类似70个核苷酸的茎环前体（pre- mirna），以及将pre- mirna细胞质加工成成熟的mirna（14）。Dicer是双齿核酸酶RNase III超家族的成员，介导后一个步骤（15-19），而前一个步骤的加工酶是未知的。在这里，我们确定了另一种RNase III，人类Drosha，作为在细胞核中执行miRNA加工起始步骤的核心核酸酶。免疫纯化的Drosha在体外切割pri-miRNA以释放pre-miRNA。此外，Drosha的RNA干扰导致体内pri-miRNA的强烈积累，pre-miRNA和成熟miRNA的减少。因此，两种RNase III蛋白Drosha和Dicer可能在mirna的逐步加工中协同工作，并在mirna介导的基因调控过程中发挥关键作用，如发育和分化过程。
Hundreds of small RNAs of similar to22 nucleotides, collectively named microRNAs (miRNAs), have been discovered recently in animals and plants(1-10). Although their functions are being unravelled(1,2,11-13), their mechanism of biogenesis remains poorly understood. miRNAs are transcribed as long primary transcripts (pri-miRNAs) whose maturation occurs through sequential processing events: the nuclear processing of the pri-miRNAs into stem-loop precursors of similar to70 nucleotides (pre-miRNAs), and the cytoplasmic processing of pre-miRNAs into mature miRNAs(14). Dicer, a member of the RNase III superfamily of bidentate nucleases, mediates the latter step(15-19), whereas the processing enzyme for the former step is unknown. Here we identify another RNase III, human Drosha, as the core nuclease that executes the initiation step of miRNA processing in the nucleus. Immunopurified Drosha cleaved pri-miRNA to release pre-miRNA in vitro. Furthermore, RNA interference of Drosha resulted in the strong accumulation of pri-miRNA and the reduction of pre-miRNA and mature miRNA in vivo. Thus, the two RNase III proteins, Drosha and Dicer, may collaborate in the stepwise processing of miRNAs, and have key roles in miRNA-mediated gene regulation in processes such as development and differentiation.