在哺乳动物中，RNA 干扰 (RNAi) 历来被作为细胞质事件进行研究。然而，在过去十年中，越来越多的报告令人信服地证明了 Argonaute (AGO) 蛋白的核定位。然而，核 RNAi 的程度及其在生物学机制中的含义仍有待阐明。我们发现，降低的Lamin A水平显着诱导SHSY5Y神经母细胞瘤和A375黑色素瘤癌细胞系中AGO2的核流入，这些细胞系通常没有核AGO2。与 A375 细胞相比，Lamin A KO 在 SHSY5Y 细胞中表现出更明显的作用，这通过细胞形态的变化、细胞增殖增加和致癌 miRNA 表达来证明。此外，Lamin A KO SHSY5Y 细胞中的 AGO fPAR-CLIP 显示 RNAi 活性显着降低。通过质谱法对核 AGO 相互作用组进行进一步探索，鉴定出 FAM120A，这是一种 RNA 结合蛋白，也是 AGO2 的已知相互作用蛋白。随后的 FAM120A fPAR-CLIP 显示 FAM120A 与 AGO 靶点共同结合，并且这种竞争降低了 RNAi 活性。因此，Lamin A 的丢失会触发核 AGO2 易位、FAM120A 介导的 RNAi 损伤以及致癌 miRNA 的上调，从而促进癌细胞增殖。© 作者 2024。由牛津大学出版社代表 Nucleic Acids Research 出版。

In mammals, RNA interference (RNAi) was historically studied as a cytoplasmic event; however, in the last decade, a growing number of reports convincingly show the nuclear localization of the Argonaute (AGO) proteins. Nevertheless, the extent of nuclear RNAi and its implication in biological mechanisms remain to be elucidated. We found that reduced Lamin A levels significantly induce nuclear influx of AGO2 in SHSY5Y neuroblastoma and A375 melanoma cancer cell lines, which normally have no nuclear AGO2. Lamin A KO manifested a more pronounced effect in SHSY5Y cells compared to A375 cells, evident by changes in cell morphology, increased cell proliferation, and oncogenic miRNA expression. Moreover, AGO fPAR-CLIP in Lamin A KO SHSY5Y cells revealed significantly reduced RNAi activity. Further exploration of the nuclear AGO interactome by mass spectrometry identified FAM120A, an RNA-binding protein and known interactor of AGO2. Subsequent FAM120A fPAR-CLIP, revealed that FAM120A co-binds AGO targets and that this competition reduces the RNAi activity. Therefore, loss of Lamin A triggers nuclear AGO2 translocation, FAM120A mediated RNAi impairment, and upregulation of oncogenic miRNAs, facilitating cancer cell proliferation.© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.