Human DDX6 effects miRNA-mediated gene silencing via direct binding to CNOT1

Rouya, Christopher; Siddiqui, Nadeem; Morita, Masahiro; Duchaîne, Thomas F.; Fabian, Marc R.; Sonenberg, Nahum

doi:10.1261/rna.045302.114

Cited by 121 publications

(154 citation statements)

References 73 publications

(155 reference statements)

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“…Our data together with previous studies indicate that human DDX6 is required for translational repression mediated by the CCR4–NOT complex in human cells (Chen et al , 2014; Mathys et al , 2014; Rouya et al , 2014). The contribution of DDX6 to this repression becomes apparent in particular for reporters that lack a poly(A) tail and hence are not degraded.…”

Section: Discussionsupporting

confidence: 86%

“…We and others have shown that DDX6 acts downstream of the CCR4–NOT complex to mediate translational repression and stimulate decapping in human cells (Chen et al , 2014; Mathys et al , 2014; Rouya et al , 2014). To further confirm that DDX6 function lies downstream of CCR4–NOT, we used tethering assays to analyze the repressive activity of a NOT1 mutant that it is impaired in binding to DDX6 but binds to CNOT2 and CNOT3 (Fig 6G, NOT1 Mut; Appendix Table S1).…”

Section: Resultsmentioning

confidence: 96%

“…It was suggested that this interaction locks eIF4A2 onto the mRNA 5′‐UTR and represses translation by blocking 43S scanning (Meijer et al , 2013). However, the interaction between NOT1 and eIF4A2 was not confirmed in subsequent studies (Chen et al , 2014; Mathys et al , 2014; Rouya et al , 2014) and the knockout of eIF4A2 in human cells does not suppress silencing (Galicia‐Vazquez et al , 2015). …”

Section: Introductionmentioning

confidence: 98%

“…Translational repression by the CCR4–NOT complex can, at least in part, be explained by a direct interaction between the NOT1 subunit and the DEAD‐box ATPase DDX6 (also known as RCK). Human DDX6 and its Drosophila melanogaster ( Dm ) ortholog Me31B repress translation, activate decapping, and play a role in silencing (Chu & Rana, 2006; Eulalio et al , 2007; Nishihara et al , 2013; Chen et al , 2014; Mathys et al , 2014; Rouya et al , 2014). …”

Section: Introductionmentioning

confidence: 99%

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mi RISC and the CCR 4– NOT complex silence mRNA targets independently of 43S ribosomal scanning

et al. 2016

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AbstractmiRNAs associate with Argonaute (AGO) proteins to silence the expression of mRNA targets by inhibiting translation and promoting deadenylation, decapping, and mRNA degradation. A current model for silencing suggests that AGOs mediate these effects through the sequential recruitment of GW182 proteins, the CCR4–NOT deadenylase complex and the translational repressor and decapping activator DDX6. An alternative model posits that AGOs repress translation by interfering with eIF4A function during 43S ribosomal scanning and that this mechanism is independent of GW182 and the CCR4–NOT complex in Drosophila melanogaster. Here, we show that miRNAs, AGOs, GW182, the CCR4–NOT complex, and DDX6/Me31B repress and degrade polyadenylated mRNA targets that are translated via scanning‐independent mechanisms in both human and Dm cells. This and additional observations indicate a common mechanism used by these proteins and miRNAs to mediate silencing. This mechanism does not require eIF4A function during ribosomal scanning.

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Section: Discussionsupporting

confidence: 86%

Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

mi RISC and the CCR 4– NOT complex silence mRNA targets independently of 43S ribosomal scanning

et al. 2016

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“…The silencing activity of miRISC is mediated by the CCR4-NOT deadenylase complex through the scaffolding subunit, CNOT1 (6)(7)(8). CNOT1 recruits the DDX6 and 4E-T (eIF4E transporter, also known as EIF4ENIF1) proteins, which are important for miRNA-mediated silencing (9)(10)(11)(12)(13)(14)(15)(16). The 4E-T protein is a conserved eIF4E-binding protein, which directly binds to the dorsal surface of eIF4E through its canonical eIF4E-binding YX 4 LL (Y 30 TKEELL) motif and impairs the eIF4E/eIF4G interaction and translation initiation (17).…”

mentioning

confidence: 99%

Cap-binding protein 4EHP effects translation silencing by microRNAs

Chapat

Jafarnejad

Matta‐Camacho

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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111

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MicroRNAs (miRNAs) play critical roles in a broad variety of biological processes by inhibiting translation initiation and by destabilizing target mRNAs. The CCR4-NOT complex effects miRNA-mediated silencing, at least in part through interactions with 4E-T (eIF4E transporter) protein, but the precise mechanism is unknown. Here we show that the cap-binding eIF4E-homologous protein 4EHP is an integral component of the miRNA-mediated silencing machinery. We demonstrate that the cap-binding activity of 4EHP contributes to the translational silencing by miRNAs through the CCR4-NOT complex. Our results show that 4EHP competes with eIF4E for binding to 4E-T, and this interaction increases the affinity of 4EHP for the cap. We propose a model wherein the 4E-T/4EHP interaction engenders a closed-loop mRNA conformation that blocks translational initiation of miRNA targets.M icroRNAs (miRNAs) are short, ∼22-nucleotide noncoding RNAs that affect gene expression in most eukaryotes. miRNAs mediate posttranscriptional silencing by guiding the miRNA-induced silencing complex (miRISC), an assembly of Argonautes and GW182/TNRC6 proteins, to target mRNAs. Target recognition initiates a succession of events: mRNA translational repression, deadenylation, and mRNA decay (1). miRNAs impair the function of eIF4F, a three-subunit complex composed of eIF4E, the m 7 GTP (cap)-interacting factor; eIF4G, a scaffolding protein; and eIF4A, a DEAD-box RNA helicase (2-5). The silencing activity of miRISC is mediated by the CCR4-NOT deadenylase complex through the scaffolding subunit, CNOT1 (6-8). CNOT1 recruits the DDX6 and 4E-T (eIF4E transporter, also known as EIF4ENIF1) proteins, which are important for miRNA-mediated silencing (9-16). The 4E-T protein is a conserved eIF4E-binding protein, which directly binds to the dorsal surface of eIF4E through its canonical eIF4E-binding YX 4 LL (Y 30 TKEELL) motif and impairs the eIF4E/eIF4G interaction and translation initiation (17). The 4E-T protein also facilitates the decay of CCR4-NOT-targeted mRNAs by linking the 3′-terminal mRNA decay machinery to the cap via its interaction with eIF4E (13).In mammals, eIF4E is the best-studied member of a family of proteins composed of eIF4E (eIF4E1), 4EHP (4E-homologous protein; eIF4E2), and eIF4E3. The 4EHP and eIF4E proteins share 28% sequence identity (18,19). The 4EHP protein is ubiquitously expressed, and it is 5-10 times less abundant than eIF4E in a number of mammalian cell lines (18)(19)(20). Like eIF4E, 4EHP binds to 4E-T, but in sharp contrast to eIF4E, it does not associate with eIF4G (18, 21). The 4EHP protein has a 30-to 100-fold weaker affinity for the cap than eIF4E due to a twoamino acid substitution in its cap-binding pocket (22).The 4EHP protein has primarily been documented as a translation repressor. In the Drosophila embryo, 4EHP associates with the RNA binding protein Bicoid to repress caudal mRNA translation (23). Similarly, 4EHP also represses the hunchback mRNA by binding to the nanos repressive element complex, which consists of nanos...

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The Ccr4‐Not complex is a key regulator of eukaryotic gene expression

2016

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The Ccr4‐Not complex is a multisubunit complex present in all eukaryotes that contributes to regulate gene expression at all steps, from production of messenger RNAs (mRNAs) in the nucleus to their degradation in the cytoplasm. In the nucleus it influences the post‐translational modifications of the chromatin template that has to be remodeled for transcription, it is present at sites of transcription and associates with transcription factors as well as with the elongating polymerase, it interacts with the factors that prepare the new transcript for export to the cytoplasm and finally is important for nuclear quality control and influences mRNA export. In the cytoplasm it is present in polysomes where mRNAs are translated and in RNA granules where mRNAs will be redirected upon inhibition of translation. It influences mRNA translatability, and is needed during translation, on one hand for co‐translational protein interactions and on the other hand to preserve translation that stalls. It is one of the relevant players during co‐translational quality control. It also interacts with factors that will repress translation or induce mRNA decapping when recruited to the translating template. Finally, Ccr4‐Not carries deadenylating enzymes and is a key player in mRNA decay, generic mRNA decay that follows normal translation termination, co‐translational mRNA decay of transcripts on which the ribosomes stall durably or which carry a non‐sense mutation and finally mRNA decay that is induced by external signaling for a change in genetic programming. Ccr4‐Not is a master regulator of eukaryotic gene expression. WIREs RNA 2016, 7:438–454. doi: 10.1002/wrna.1332For further resources related to this article, please visit the WIREs website.

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Human DDX6 effects miRNA-mediated gene silencing via direct binding to CNOT1

Cited by 121 publications

References 73 publications

mi RISC and the CCR 4– NOT complex silence mRNA targets independently of 43S ribosomal scanning

mi RISC and the CCR 4– NOT complex silence mRNA targets independently of 43S ribosomal scanning

Cap-binding protein 4EHP effects translation silencing by microRNAs

The Ccr4‐Not complex is a key regulator of eukaryotic gene expression

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