Department of Biochemistry, Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany.
Nucleic Acids Res. 2012 Jul;40(12):5651-65. doi: 10.1093/nar/gks218. Epub 2012 Mar 7.
GW182 family proteins are essential for miRNA-mediated gene silencing in animal cells. They are recruited to miRNA targets via interactions with Argonaute proteins and then promote translational repression and degradation of the miRNA targets. The human and Drosophila melanogaster GW182 proteins share a similar domain organization and interact with PABPC1 as well as with subunits of the PAN2-PAN3 and CCR4-NOT deadenylase complexes. The homologous proteins in Caenorhabditis elegans, AIN-1 and AIN-2, lack most of the domains present in the vertebrate and insect proteins, raising the question as to how AIN-1 and AIN-2 contribute to silencing. Here, we show that both AIN-1 and AIN-2 interact with Argonaute proteins through GW repeats in the middle region of the AIN proteins. However, only AIN-1 interacts with C. elegans and D. melanogaster PABPC1, PAN3, NOT1 and NOT2, suggesting that AIN-1 and AIN-2 are functionally distinct. Our findings reveal a surprising evolutionary plasticity of the GW182 protein interaction network and demonstrate that binding to PABPC1 and deadenylase complexes has been maintained throughout evolution, highlighting the significance of these interactions for silencing.
GW182 家族蛋白对于动物细胞中的 miRNA 介导的基因沉默至关重要。它们通过与 Argonaute 蛋白的相互作用被招募到 miRNA 靶标上，然后促进 miRNA 靶标的翻译抑制和降解。人类和黑腹果蝇的 GW182 蛋白具有相似的结构域组织，并与 PABPC1 以及 PAN2-PAN3 和 CCR4-NOT 脱腺苷酸酶复合物的亚基相互作用。秀丽隐杆线虫中的同源蛋白 AIN-1 和 AIN-2 缺乏脊椎动物和昆虫蛋白中存在的大多数结构域，这引发了一个问题，即 AIN-1 和 AIN-2 如何参与沉默。在这里，我们表明 AIN-1 和 AIN-2 都通过 AIN 蛋白中间区域的 GW 重复与 Argonaute 蛋白相互作用。然而，只有 AIN-1 与秀丽隐杆线虫和黑腹果蝇的 PABPC1、PAN3、NOT1 和 NOT2 相互作用，这表明 AIN-1 和 AIN-2 在功能上是不同的。我们的发现揭示了 GW182 蛋白相互作用网络惊人的进化灵活性，并证明了与 PABPC1 和脱腺苷酸酶复合物的结合在整个进化过程中都得到了保留，突出了这些相互作用对于沉默的重要性。
