The let-7 target gene mouse lin-41 is a stem cell specific E3 ubiquitin ligase for the miRNA pathway protein Ago2
The let-7 target gene mouse lin-41 is a stem cell specific E3 ubiquitin ligase for the miRNA pathway protein Ago2
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DOI：
10.1038/ncb1987
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发表时间：
2009-12-01
影响因子：
21.3
通讯作者：
Wulczyn, F. Gregory
中科院分区：
文献类型：
--
作者：
Rybak, Agnieszka;Fuchs, Heiko;Wulczyn, F. Gregory
Let-7miRNA及其靶基因Lin-28在控制多能性的调控电路中相互作用。我们研究了另一个let-7靶点mLin41(LIN-41的小鼠同源物)，作为该电路的潜在贡献者。我们证明了mLin41蛋白存在于几个干细胞的小生境中，包括胚胎外胚层、表皮和雄性生殖细胞系。MLin41与P体标记物和miRNA途径蛋白Ago2、Mov10和Tnrc6b共定位于细胞质内。在共沉淀实验中，mLin41与DICER和ArgAerte蛋白Ago1、Ago2和Ago4相互作用。此外，我们发现mLin41在自身泛素化实验中作为E3泛素连接酶发挥作用，并且在体外和体内mLin41介导Ago2的泛素化。MLin41的过度表达和缺失导致了Ago2蛋白水平的反向变化，提示mLin41参与了Ago2周转的调节。MLin41至少部分地通过拮抗Ago2来干扰let-7和miR-124的靶mRNAs的沉默。此外，mLin41与多能因子Lin-28协同抑制了let-7的活性，揭示了干细胞中let-7的双重调控机制。
The let-7 miRNA and its target gene Lin-28 interact in a regulatory circuit controlling pluripotency. We investigated an additional let-7 target, mLin41 (mouse homologue of lin-41), as a potential contributor to this circuit. We demonstrate the presence of mLin41 protein in several stem cell niches, including the embryonic ectoderm, epidermis and male germ line. mLin41 colocalized to cytoplasmic foci with P-body markers and the miRNA pathway proteins Ago2, Mov10 and Tnrc6b. In co-precipitation assays, mLin41 interacted with Dicer and the Argonaute proteins Ago1, Ago2 and Ago4. Moreover, we show that mLin41 acts as an E3 ubiquitin ligase in an auto-ubiquitylation assay and that mLin41 mediates ubiquitylation of Ago2 in vitro and in vivo. Overexpression and depletion of mLin41 led to inverse changes in the level of Ago2 protein, implicating mLin41 in the regulation of Ago2 turnover. mLin41 interfered with silencing of target mRNAs for let-7 and miR-124, at least in part by antagonizing Ago2. Furthermore, mLin41 cooperated with the pluripotency factor Lin-28 in suppressing let-7 activity, revealing a dual control mechanism regulating let-7 in stem cells.