HASTY modulates miRNA biogenesis by linking pri-miRNA transcription and processing
HASTY modulates miRNA biogenesis by linking pri-miRNA transcription and processing
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DOI：
10.1016/j.molp.2020.12.019
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发表时间：
2021-03-01
期刊：
影响因子：
27.5
通讯作者：
Manavella, Pablo A.
中科院分区：
文献类型：
--
作者：
Cambiagno, Damian A.;Giudicatti, Axel J.;Manavella, Pablo A.
由microRNA（miRNAs）介导的转录后基因沉默调节许多发育和应激反应途径。在过去的二十年中，HASTY（HST），人类EXPORTIN 5的直系同源物，被认为是将植物miRNA从细胞核输出到细胞质的候选蛋白。在这里，我们报告说，HST功能的miRNA途径独立于其货物输出活动在拟南芥。我们发现HST穿梭受损的拟南芥突变体表现出正常的亚细胞分布的miRNA。有趣的是，蛋白质-蛋白质相互作用和显微镜分析表明，HST直接与微处理器核心组件DCL 1通过其N-末端结构域相互作用。此外，质谱分析表明，HST也相互作用独立的N-末端结构域与介质复合物亚基MED 37。进一步的实验表明，HST可以作为一种支架，通过稳定DCL 1-MED 37复合物，促进DCL 1募集到基因组MIRNA位点，这反过来又促进初级miRNA转录物（pri-miRNA）的转录和正确加工。总之，这些结果表明，HST可能与MIRNA基因处的miRNA生物合成复合物的形成有关，促进pri-miRNA的转录和加工，而不是直接从细胞核输出加工的miRNA。
Post-transcriptional gene silencing mediated by microRNAs (miRNAs) modulates numerous developmental and stress response pathways. For the last two decades, HASTY (HST), the ortholog of human EXPORTIN 5, was considered to be a candidate protein that exports plant miRNAs from the nucleus to the cytoplasm. Here, we report that HST functions in the miRNA pathway independent of its cargo-exporting activity in Arabidopsis. We found that Arabidopsis mutants with impaired HST shuttling exhibit normal subcellular distribution of miRNAs. Interestingly, protein-protein interaction and microscopy assays showed that HST directly interacts with the microprocessor core component DCL1 through its N-terminal domain. Moreover, mass spectrometry analysis revealed that HST also interacts independently of its N-terminal domain with the mediator complex subunit MED37. Further experiments revealed that HST could act as a scaffold to facilitate the recruitment of DCL1 to genomic MIRNA loci by stabilizing the DCL1-MED37 complex, which in turn promotes the transcription and proper processing of primary miRNA transcripts (pri-miRNAs). Taken together, these results suggest that HST is likely associated with the formation of the miRNA biogenesis complex at MIRNA genes, promoting the transcription and processing of pri-miRNAs rather than the direct export of processed miRNAs from the nucleus.