The DDX6–4E-T interaction mediates translational repression and P-body assembly

Kamenska, Anastasiia; Simpson, Clare; Vindry, Caroline; Broomhead, Helen; Bénard, Marianne; Ernoult‐Lange, Michèle; Lee, Benjamin P.; Harries, Lorna W.; Weil, Dominique; Standart, Nancy

doi:10.1093/nar/gkw565

Cited by 109 publications

(119 citation statements)

References 79 publications

Supporting

Mentioning

110

Contrasting

Unclassified

Order By: Relevance

“…Our previous work showed that in addition to the C-terminal 4E-T fragment, the middle region of 4E-T (residues 335-490) also interacts with the LSM domain of LSM14 in vitro (Nishimura et al, 2015). This finding was recently corroborated by other studies demonstrating the middle region to be sufficient for this interaction (Kamenska et al, 2016). The middle and C-terminal regions contain conserved hydrophobic residues that can be partially aligned ( Fig EV1A).…”

Section: Discussionsupporting

confidence: 61%

Molecular architecture of LSM 14 interactions involved in the assembly of mRNA silencing complexes

et al. 2018

View full text Add to dashboard Cite

The LSM domain-containing protein LSM14/Rap55 plays a role in mRNA decapping, translational repression, and RNA granule (P-body) assembly. How LSM14 interacts with the mRNA silencing machinery, including the eIF4E-binding protein 4E-T and the DEAD-box helicase DDX6, is poorly understood. Here we report the crystal structure of the LSM domain of LSM14 bound to a highly conserved C-terminal fragment of 4E-T. The 4E-T C-terminus forms a bi-partite motif that wraps around the N-terminal LSM domain of LSM14. We also determined the crystal structure of LSM14 bound to the C-terminal RecA-like domain of DDX6. LSM14 binds DDX6 via a unique non-contiguous motif with distinct directionality as compared to other DDX6-interacting proteins. Together with mutational and proteomic studies, the LSM14-DDX6 structure reveals that LSM14 has adopted a divergent mode of binding DDX6 in order to support the formation of mRNA silencing complexes and P-body assembly.

show abstract

Section: Discussionsupporting

confidence: 61%

Molecular architecture of LSM 14 interactions involved in the assembly of mRNA silencing complexes

et al. 2018

View full text Add to dashboard Cite

show abstract

“…1C). Likewise, endogenous 4EHP coprecipitated with endogenous DDX6, as well as HA-tagged PATL-1, a physical partner of CCR4-NOT, DDX6, and 4E-T (12,32,33) (Fig. 1 D and E).…”

Section: Resultsmentioning

confidence: 85%

“…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.

111

View full text Add to dashboard Cite

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...

show abstract

“…Interestingly, our 3D‐culture experiments showed that silencing of DDX6 induced growth inhibition of tumor spheroid formation through the suppression of the c‐Myc expression (Figure ). In normal cells, DDX6 is a key component for the assembly of P‐bodies, which are involved in post‐transcriptional regulation and associated with decapping complex, translation repression, the RNA‐induced silencing complex (RISC), and the Ccr4/Not complex . Thus, DDX6 most likely acts as translation repressor.…”

Section: Discussionmentioning

confidence: 99%

“…In normal cells, DDX6 is a key component for the assembly of P-bodies, which are involved in post-transcriptional regulation and associated with decapping complex, translation repression, the RNA-induced silencing complex (RISC), and the Ccr4/Not complex. 14,30 Thus, DDX6 most likely acts as translation repressor. However, the higher expression of DDX6 in cancer cells deregulates the above-mentioned translational regulation, but the reason why needs to be clarified.…”

Section: Discussionmentioning

confidence: 99%

Oncogene RNA helicase DDX6 promotes the process of c‐Myc expression in gastric cancer cells

Taniguchi

Iwatsuki

Sugito

et al. 2018

Molecular Carcinogenesis

View full text Add to dashboard Cite

Human DEAD-box RNA helicase gene DDX6 was cloned from B-cell lymphoma cell line RC-K8. Previously, we reported that DDX6 acts as oncogene in several cancers such as colorectal cancer and hepatocellular carcinoma. However, the detailed mechanism of DDX6 action in carcinogenesis is largely unknown. In this study, we examined the functions of DDX6 in clinical gastric cancer (GC) samples and GC cells. DDX6 protein expression levels of cancer samples were higher than those of the adjacent normal tissues in 25 clinical GC samples (median value: 1.4 times higher). Also, the results of an RNA immunoprecipitation-assay (RIP-assay) showed that DDX6 associated with c-Myc mRNA. Moreover, enforced overexpression of DDX6 promoted both mRNA and protein expression of c-Myc in GC cells. On the other hand, the gene silencing of DDX6 induced growth suppression through down-regulation of c-Myc in GC cells grown in either two or three dimensions. Furthermore, c-Myc mRNA expression levels of cancer samples were higher than those of the adjacent normal tissues in DDX6 up-regulated-GC clinical samples. Our findings in this study suggested that DDX6 acted as oncogene in GC cells through promotion of c-Myc expression by association with the mRNA of c-Myc.

show abstract

The DDX6–4E-T interaction mediates translational repression and P-body assembly

Cited by 109 publications

References 79 publications

Molecular architecture of LSM 14 interactions involved in the assembly of mRNA silencing complexes

Molecular architecture of LSM 14 interactions involved in the assembly of mRNA silencing complexes

Cap-binding protein 4EHP effects translation silencing by microRNAs

Oncogene RNA helicase DDX6 promotes the process of c‐Myc expression in gastric cancer cells

Contact Info

Product

Resources

About