Jakymiw, A. et al. Disruption of GW bodies impairs mammalian RNA interference. Nat. Cell Biol. 7, 1267-1274

Department of Biochemistry and Molecular Biology, The University of Calgary, Calgary, Alberta, Canada
Nature Cell Biology (Impact Factor: 19.68). 01/2006; 7(12):1267-74. DOI: 10.1038/ncb1334
Source: PubMed


The GW182 RNA-binding protein was initially shown to associate with a specific subset of mRNAs and to reside within discrete cytoplasmic foci named GW bodies (GWBs). GWBs are enriched in proteins that are involved in mRNA degradation. Recent reports have shown that exogenously introduced human Argonaute-2 (Ago2) is also enriched in GWBs, indicating that RNA interference function may be somehow linked to these structures. In this report, we demonstrate that endogenous Ago2 and transfected small interfering RNAs (siRNAs) are also present within these same cytoplasmic bodies and that the GW182 protein interacts with Ago2. Disruption of these cytoplasmic foci in HeLa cells interferes with the silencing capability of a siRNA that is specific to lamin-A/C. Our data support a model in which GW182 and/or the microenvironment of the cytoplasmic GWBs contribute to the RNA-induced silencing complex and to RNA silencing.

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    • "Processing bodies (P-bodies), cytoplasmic foci containing enzymes acting in mRNA turnover, were first implicated as sites of RNA silencing (Jakymiw et al, 2005; Liu et al, 2005; Pillai et al, 2005). In animals, Ago, miRNAs, and target mRNAs were detected in P-bodies and P-bodies were proposed to be sites of sRNA-mediated translational inhibition (Jakymiw et al, 2005; Liu et al, 2005; Pillai et al, 2005). However, visible P-body formation was found to be dispensable for miRNAmediated gene silencing, raising the possibility that the localization of the RNA silencing machinery and target mRNAs to P-bodies is the consequence rather than the cause of RNA silencing activity (Chu & Rana, 2006; Eulalio et al, 2007). "
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    ABSTRACT: microRNAs (miRNAs) and small interfering RNAs (siRNAs) are small RNAs that repress gene expression at the post-transcriptional level in plants and animals. Small RNAs guide Argonaute-containing RNA-induced silencing complexes to target RNAs in a sequence-specific manner, resulting in mRNA deadenylation followed by exonucleolytic decay, mRNA endonucleolytic cleavage, or translational inhibition. Although our knowledge of small RNA biogenesis, turnover, and mechanisms of action has dramatically expanded in the past decade, the subcellular location of small RNA-mediated RNA silencing still needs to be defined. In contrast to the prevalent presumption that RNA silencing occurs in the cytosol, emerging evidence reveals connections between the endomembrane system and small RNA activities in plants and animals. Here, we summarize the work that uncovered this link between small RNAs and endomembrane compartments and present an overview of the involvement of the endomembrane system in various aspects of RNA silencing. We propose that the endomembrane system is an integral component of RNA silencing that has been long overlooked and predict that a marriage between cell biology and RNA biology holds the key to a full understanding of post-transcriptional gene regulation by small RNAs.
    Full-text · Article · May 2014 · The EMBO Journal
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    • "The most popular hypothesis posits that mRNAs under miRNA-mediated inhibition are stored (Brengues et al., 2005; Bhattacharyya et al., 2006) and degraded (Eulalio et al., 2007; Parker and Sheth, 2007) into cytoplasmic particles called processing bodies or glycine-tryptophan (GW) bodies. These cytoplasmic foci are free of translational machinery but are enriched in proteins that are required for efficient mRNA inhibition (Jakymiw et al., 2005; Liu et al., 2005; Rehwinkel et al., 2005; Behm-Ansmant et al., 2006). "
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    ABSTRACT: MicroRNAs (miRNAs) are emerging as master regulators of gene expression in the nervous system where they contribute not only to brain development but also to neuronal network homeostasis and plasticity. Their function is the result of a cascade of events including miRNA biogenesis, target recognition, and translation inhibition. It has been suggested that miRNAs are major switches of the genome owing to their ability to regulate multiple genes at the same time. This regulation is essential for normal neuronal activity and, when affected, can lead to drastic pathological conditions. As an example, we illustrate how deregulation of miRNAs can affect neuronal plasticity leading to chronic pain. The origin of pain and its dual role as a key physiological function and a debilitating disease has been highly debated until now. The incidence of chronic pain is estimated to be 20-25% worldwide, thus making it a public health problem. Chronic pain can be considered as a form of maladaptive plasticity. Long-lasting modifications develop as a result of global changes in gene expression, and are thus likely to be controlled by miRNAs. Here, we review the literature on miRNAs and their targets responsible for maladaptive plasticity in chronic pain conditions. In addition, we conduct a retrospective analysis of miRNA expression data published for different pain models, taking into account recent progress in our understanding of the role of miRNAs in neuronal plasticity.
    Full-text · Article · Feb 2014 · Frontiers in Cellular Neuroscience
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    • "P bodies are multimegadalton RNA-protein complexes that function in mRNA surveillance and may associate with miRNAs, miRNA-targeted mRNAs, and Ago2 (reviewed in Eulalio et al., 2007a; Parker and Sheth, 2007). MK2 phosphorylation of Ago2 at S387 has been shown to facilitate Ago2 localization to these complexes (Zeng et al., 2008), and Ago2 is known to bind the P body marker GW182 (Jakymiw et al., 2005). We therefore sought to assess Akt's impact on the physical association of Ago2 and GW182. "
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    ABSTRACT: A high-throughput RNA interference (RNAi) screen targeting 542 genes of the human kinome was used to discover regulators of RNAi. Here we report that the proto-oncogene Akt-3/PKBγ (Akt3) phosphorylates Argonaute 2 (Ago2) at S387, which downregulates cleavage and upregulates translational repression of endogenous microRNA (miRNA)-targeted messenger RNAs (mRNAs). We further demonstrate that Akt3 coimmunoprecipitates with Ago2 and phosphorylation of Ago2 at S387 facilitates its interaction with GW182 and localization to cytoplasmic processing bodies (P bodies), where miRNA-targeted mRNAs are thought to be stored and degraded. Therefore, Akt3-mediated phosphorylation of Ago2 is a molecular switch between target mRNA cleavage and translational repression activities of Ago2.
    Full-text · Article · Apr 2013 · Molecular cell
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