Human UPF1 Participates in Small RNA-Induced mRNA Downregulation
Human UPF1 Participates in Small RNA-Induced mRNA Downregulation
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DOI：
10.1128/mcb.00653-09
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发表时间：
2009-11-01
影响因子：
5.3
通讯作者：
Kim, V. Narry
中科院分区：
文献类型：
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作者：
Jin, Hua;Suh, Mi Ra;Kim, V. Narry
MicroRNA (miRNA) 是内源性反义调节因子，可触发核酸内切 mRNA 切割、翻译抑制和/或 mRNA 衰减。 miRNA 介导的基因调控对于许多生物途径都很重要，但其潜在机制仍在严格研究中。在这里，我们将人类 UPF1 (hUPF1) 确定为一种有助于 RNA 沉默的蛋白质。当 hUPF1 被敲低时，miRNA 靶标就会上调。 hUPF1 的缺失还会增加小干扰 RNA (siRNA) 的脱靶信息，这些信息与转染的 siRNA 不完全互补。相反，当过度表达时，野生型 hUPF1 会下调 miRNA 靶标。 hUPF1 的解旋酶结构域突变体无法抑制 miRNA 靶标。 hUPF1 与人类 Argonaute 1 (hAGO1) 和 hAGO2 相互作用，并与加工体中的 hAGO1 和 hAGO2 共定位，加工体是已知的翻译抑制和 mRNA 破坏的位点。我们进一步发现，当 hUPF1 耗尽时，与 hAGO2 结合的目标消息量会减少。因此，我们的数据表明 hUPF1 可能通过促进 RNA 诱导的沉默复合物与靶标的结合并加速 mRNA 的衰变来参与 RNA 沉默。
MicroRNAs (miRNAs) are endogenous antisense regulators that trigger endonucleolytic mRNA cleavage, translational repression, and/or mRNA decay. miRNA-mediated gene regulation is important for numerous biological pathways, yet the underlying mechanisms are still under rigorous investigation. Here we identify human UPF1 (hUPF1) as a protein that contributes to RNA silencing. When hUPF1 is knocked down, miRNA targets are upregulated. The depletion of hUPF1 also increases the off-target messages of small interfering RNAs (siRNAs), which are imperfectly complementary to transfected siRNAs. Conversely, when overexpressed, wild-type hUPF1 downregulates miRNA targets. The helicase domain mutant of hUPF1 fails to suppress miRNA targets. hUPF1 interacts with human Argonaute 1 (hAGO1) and hAGO2 and colocalizes with hAGO1 and hAGO2 in processing bodies, which are known to be the sites for translational repression and mRNA destruction. We further find that the amounts of target messages bound to hAGO2 are reduced when hUPF1 is depleted. Our data thus suggest that hUPF1 may participate in RNA silencing by facilitating the binding of the RNA-induced silencing complex to the target and by accelerating the decay of the mRNA.