Quantitative analysis of Argonaute protein reveals microRNA-dependent localization to stress granules
Quantitative analysis of Argonaute protein reveals microRNA-dependent localization to stress granules
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DOI：
10.1073/pnas.0608845103
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发表时间：
2006-11-28
影响因子：
11.1
通讯作者：
Sharp, Phillip A.
中科院分区：
文献类型：
--
作者：
Leung, Anthony K. L.;Calabrese, J. Mauro;Sharp, Phillip A.
Argonaute 蛋白与 microRNA (miRNA) 结合，通过部分碱基配对结合 mRNA，主要抑制动物体内的翻译。一部分 Argonaute 蛋白和 miRNA 在生化上与多核糖体共沉积，而另一部分则矛盾地积聚在细胞质中的无核糖体加工体 (PB) 中。在本报告中，我们定量描述了不同细胞状态下活细胞中 Argonaute 蛋白的定位和动态。我们发现大部分 Argonaute 广泛分布在细胞质中，当细胞受到应激时，Argonaute 蛋白会积累到新组装的结构中，除了 PB 之外，称为应激颗粒 (SG)。 Argonaute 蛋白在不同结构下表现出不同的动力学：SG 处的交换速度更快，PB 处的交换速度慢得多。此外，Argonaute 蛋白定位到 SG 需要 miRNA，但不需要 PB。这些定量动力学数据提供了对 miRNA 介导的抑制的见解。
Argonaute proteins associate with microRNAs (miRNAs) that bind mRNAs through partial base-pairings to primarily repress translation in animals. A fraction of Argonaute proteins and miRNAs biochemically cosediment with polyribosomes, yet another fraction paradoxically accumulates in ribosome-free processing bodies (PBs) in the cytoplasm. In this report, we give a quantitative account of the Argonaute protein localization and dynamics in living cells in different cellular states. We find that the majority of Argonaute is distributed diffusely in the cytoplasm, and, when cells are subjected to stress, Argonaute proteins accumulate to newly assembled structures known as stress granules (SGs) in addition to PBs. Argonaute proteins displayed distinct kinetics at different structures: exchange faster at SGs and much slower at PBs. Further, miRNAs are required for the Argonaute protein localization to SGs but not PBs. These quantitative kinetic data provide insights into miRNA-mediated repression.