Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany.
Mol Cell. 2011 Oct 7;44(1):120-33. doi: 10.1016/j.molcel.2011.09.007.
miRNAs are posttranscriptional regulators of gene expression that associate with Argonaute and GW182 proteins to repress translation and/or promote mRNA degradation. miRNA-mediated mRNA degradation is initiated by deadenylation, although it is not known whether deadenylases are recruited to the mRNA target directly or by default, as a consequence of a translational block. To answer this question, we performed a screen for potential interactions between the Argonaute and GW182 proteins and subunits of the two cytoplasmic deadenylase complexes. We found that human GW182 proteins recruit the PAN2-PAN3 and CCR4-CAF1-NOT deadenylase complexes through direct interactions with PAN3 and NOT1, respectively. These interactions are critical for silencing and are conserved in D. melanogaster. Our findings reveal that GW182 proteins provide a docking platform through which deadenylase complexes gain access to the poly(A) tail of miRNA targets to promote their deadenylation, and they further indicate that deadenylation is a direct effect of miRNA regulation.
miRNAs 是基因表达的转录后调控因子，它们与 Argonaute 和 GW182 蛋白结合，抑制翻译和/或促进 mRNA 降解。miRNA 介导的 mRNA 降解是由去腺苷酸化引发的，尽管尚不清楚去腺苷酸酶是否直接或默认地被招募到 mRNA 靶标上，作为翻译受阻的结果。为了回答这个问题，我们进行了筛选，以寻找 Argonaute 和 GW182 蛋白与两种细胞质去腺苷酸酶复合物的亚基之间的潜在相互作用。我们发现人类 GW182 蛋白通过与 PAN3 和 NOT1 的直接相互作用，分别募集 PAN2-PAN3 和 CCR4-CAF1-NOT 去腺苷酸酶复合物。这些相互作用对于沉默至关重要，并且在 D. melanogaster 中是保守的。我们的研究结果表明，GW182 蛋白提供了一个对接平台，通过该平台，去腺苷酸酶复合物可以进入 miRNA 靶标的 poly(A)尾巴，促进其去腺苷酸化，并且进一步表明去腺苷酸化是 miRNA 调节的直接效应。
