Homo sapiens
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ABSTRACT:
OTHER RELATED OMICS DATASETS IN: E-GEOD-56887
PROVIDER: PRJNA244865 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Rocaglamide A (RocA) typifies a class of protein synthesis inhibitors that selectively kill aneuploid tumor cells and repress translation of specific mRNAs. RocA targets eukaryotic initiation factor 4A (eIF4A), an ATP-dependent DEAD-box RNA helicase; its mRNA selectivity is proposed to reflect highly structured 5â² UTRs that depend strongly on eIF4A-mediated unwinding. However, rocaglate treatment may not phenocopy the loss of eIF4A activity, as these drugs actually increase the affinity between eIF4A and RNA. Here, we show that secondary structure in 5â² UTRs is only a minor determinant for RocA selectivity and RocA does not repress translation by reducing eIF4A availability. Rather, in vitro and in cells, RocA specifically clamps eIF4A onto polypurine sequences in an ATP-independent manner. This artificially clamped eIF4A blocks 43S scanning, leading to premature, upstream translation initiation and reducing protein expression from transcripts bearing the RocA-eIF4A target sequence. In elucidating the mechanism of selective translation repression by this lead anti-cancer compound, we provide an example of a drug stabilizing sequence-selective RNA-protein interactions. Bind-n-Seq and iCLIP-Seq
2016-06-15 | E-GEOD-79392 | biostudies-arrayexpress
Project description:Rocaglamide A (RocA) typifies a class of protein synthesis inhibitors that selectively kill aneuploid tumor cells and repress translation of specific mRNAs. RocA targets eukaryotic initiation factor 4A (eIF4A), an ATP-dependent DEAD-box RNA helicase; its mRNA selectivity is proposed to reflect highly structured 5′ UTRs that depend strongly on eIF4A-mediated unwinding. However, rocaglate treatment may not phenocopy the loss of eIF4A activity, as these drugs actually increase the affinity between eIF4A and RNA. Here, we show that secondary structure in 5′ UTRs is only a minor determinant for RocA selectivity and RocA does not repress translation by reducing eIF4A availability. Rather, in vitro and in cells, RocA specifically clamps eIF4A onto polypurine sequences in an ATP-independent manner. This artificially clamped eIF4A blocks 43S scanning, leading to premature, upstream translation initiation and reducing protein expression from transcripts bearing the RocA-eIF4A target sequence. In elucidating the mechanism of selective translation repression by this lead anti-cancer compound, we provide an example of a drug stabilizing sequence-selective RNA-protein interactions.
2016-06-15 | GSE79392 | GEO
Project description:Rocaglamide A (RocA) typifies a novel class of protein synthesis inhibitors that selectively kill aneuploid tumor cells and repress translation of specific mRNAs. RocA targets eukaryotic initiation factor 4A (eIF4A), the prototypical DEAD-box RNA helicase, and its mRNA selectivity is proposed to reflect highly structured 5′ UTRs that are very dependent on eIF4A-mediated unwinding. Here, we show that secondary structure in 5′ UTRs is only a minor determinant for RocA selectivity and RocA does not repress translation by reducing eIF4A activity. Rather, in vitro and in vivo, RocA clamps eIF4A onto a specific sequence motif even after ATP hydrolysis. This artificially clamped eIF4A blocks 43S scanning, leading to premature, upstream translation initiation and reducing gene expression on transcripts bearing the RocA-eIF4A target sequence. In elucidating the mechanism of this lead anti-cancer compound and explaining its mRNA selectivity, we provide the first example of a drug stabilizing sequence-specific RNA-protein interactions.
2016-06-15 | GSE70211 | GEO
Project description:Ribosome profiling of MDA-MB-231 cells treated with Silvestrol to monitor transcriptome wide, eIF4A-dependent changes in translation efficiency Translation efficiency (TE) of mRNAs dervied from ribosome footprints was monitored in the presence or absence of 25 nM Silvestrol, an inhibitor of eukaryotic translation initiation factor 4A (eIF4A). Transcripts with reduced TE in the presence of Silvestrol were compare to transcripts with reduced TE in the presence of INK128, a catalytic mTOR inhbitor.
2014-09-13 | E-GEOD-61375 | biostudies-arrayexpress
Project description:A novel class of translation inhibitors isolated from Aglaia plants, exemplified by Rocaglamide A (RocA), shows promise as an anti-cancer therapy. RocA converts its molecular target, translation initiation factor 4A (eIF4A), a DEAD-box protein, into a purine-selective RNA-binding protein that represses protein synthesis from a subset of mRNAs. This unusual mechanism of action raises the question of how the drug induces selectivity for polypurine sequences. Furthermore, as eIF4A is found in all eukaryotes, it is unclear how Aglaia resists the effects of RocA. Here, we assembled the Aglaia transcriptome de novo and identified highly specific mutations in eIF4A that enable it to evade RocA-dependent translation inhibition. Furthermore, we determined the crystal structure of the human eIF4A1•ATP analog•RocA•polypurine RNA complex. RocA binds residues mutated in Aglaia and intercalates between consecutive purines at a sharp RNA bend, revealing the structural basis of polypurine-selective translational inhibition by RocA in human and resistance in Aglaia.
2018-12-30 | GSE102720 | GEO
Project description:Translational dysregulation is an emerging hallmark of cancer, and increased activity of the mRNA helicase eIF4A is associated with poor survival in malignancies. This is believed to be due to the unwinding of secondary structures within the 5’UTRs of oncogenic mRNAs, with studies showing that in general eIF4A-dependent mRNAs have longer 5’UTRs with more stable secondary structures, yet our ability to predict eIF4A-dependency from 5’UTR properties alone remains poor. We therefore used Structure-seq 2 to measure transcriptome-wide changes in RNA structure in MCF7 cells, following eIF4A inhibition with hippuristanol. This technique measures the single-strandedness of RNA by specific and rapid methylation of single-stranded adenosines and cytosines with Dimethyl Sulphate (DMS). When paired with polysome profiling data to identify which mRNAs are most translationally repressed, we can identify the structural determinants of eIF4A-dependency. Upon eIF4A inhibition, both 5’UTRs and CDSs become generally more structured, while overall this was not observed for 3’UTRs. This was most pronounced in CDSs, supporting recent findings that the ribosome sculpts RNA structure in this region. 5’UTRs are generally more structured at their 5’ ends and highly translated mRNAs are less structured just upstream of the CDS. Following eIF4A inhibition, the 5’UTR is remodelled. eIF4A-dependent mRNAs have greater localised gains of structure. The degree of these structural changes is strongly correlated with 5’UTR length, explaining why eIF4A-dependent mRNAs have longer 5’UTRs. Crucially, in eIF4A-dependent mRNAs these highly-structured elements are located predominantly at the 3’ end of the 5’UTR, suggesting that increased structure just upstream of the CDS is most inhibitory to translation following eIF4A inhibition and is a key determinant of eIF4A-dependency.
2019-11-26 | GSE134865 | GEO
Project description:Rocaglamide A (RocA) typifies a novel class of protein synthesis inhibitors that selectively kill aneuploid tumor cells and repress translation of specific mRNAs. RocA targets eukaryotic initiation factor 4A (eIF4A), the prototypical DEAD-box RNA helicase, and its mRNA selectivity is proposed to reflect highly structured 5â² UTRs that are very dependent on eIF4A-mediated unwinding. Here, we show that secondary structure in 5â² UTRs is only a minor determinant for RocA selectivity and RocA does not repress translation by reducing eIF4A activity. Rather, in vitro and in vivo, RocA clamps eIF4A onto a specific sequence motif even after ATP hydrolysis. This artificially clamped eIF4A blocks 43S scanning, leading to premature, upstream translation initiation and reducing gene expression on transcripts bearing the RocA-eIF4A target sequence. In elucidating the mechanism of this lead anti-cancer compound and explaining its mRNA selectivity, we provide the first example of a drug stabilizing sequence-specific RNA-protein interactions. Ribosome profiling, mRNA-Seq, RIP-Seq, and Bind-n-Seq Ribosome profiling for sample 1-5, and 11-15. Sample1 and 2 are replicates of control of DMSO treatment for sample 3-5, and 11, with RocA and PP242 treatments. Sample 12 and 13 are replicates of control of DMSO treatment for sample 14 and 15 with Hipp treatments. mRNA-Seq for sample 6-10. Sample 6 and 7 are replicates of control of DMSO treatment for sample 8-10 with RocA treatments. RIP-Seq for 16-19. Sample 16 and 17 are replicates of control of DMSO treatment for sample 18-19 with RocA treatments. Bind-n-Seq for 20-23. Sample 21 is control of DMSO treatment for sample 22-23 with RocA treatments. Sample 20 is a input contol for protein-bound fraction of sample 21. We stably expressed SBP (streptavidin binding peptide)-tagged eIF4A in HEK 293T-REx cells and purified it via M270 streptavidin beads (life techonologies).
2016-06-15 | E-GEOD-70211 | biostudies-arrayexpress
Project description:DEAD-box RNA helicases eIF4A and Ded1 are believed to promote translation initiation by resolving mRNA secondary structures that impede ribosome attachment at the mRNA 5’ end or subsequent scanning of the 5’UTR, but whether they perform distinct functions or act redundantly in vivo is poorly understood. We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling. Despite similar reductions in bulk translation, inactivation of a cold-sensitive Ded1 mutant substantially reduced the TEs of >600 mRNAs, whereas inactivation of a temperature-sensitive eIF4A mutant yielded <40 similarly impaired mRNAs. The broader requirement for Ded1 did not reflect more pervasive secondary structures at low temperature, as inactivation of temperature-sensitive and cold-sensitive ded1 mutants gave highly correlated results. Interestingly, Ded1-dependent mRNAs exhibit greater than average 5’UTR length and propensity for secondary structure, implicating Ded1 in scanning though structured 5' UTRs. Reporter assays confirmed that cap- distal stem-loop insertions increase dependence on Ded1 but not eIF4A for efficient translation. While only a small fraction of mRNAs is strongly dependent on eIF4A, this dependence is significantly correlated with requirements for Ded1 and 5’UTR features characteristic of Ded1- dependent mRNAs. Our findings suggest that Ded1 is critically required to promote scanning through secondary structures within 5’UTRs; and while eIF4A cooperates with Ded1 in this function, it also promotes a step of initiation common to virtually all yeast mRNAs. We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling.The study includes 32 samples, comprised of 16 mRNA-Seq samples and 16 ribosome footprint profiling samples, derived from biological replicates of 3 mutant strains, ded1-cs, ded1-ts and tif1-ts, and the corresponding wild-type strains. The tif1-ts mutant and its wild-type counterpart were analyzed at 30°C and 37°C.
2015-03-02 | E-GEOD-66411 | biostudies-arrayexpress
Project description:DEAD-box RNA helicases eIF4A and Ded1 promote translation by resolving mRNA secondary structures that impede preinitiation complex (PIC) attachment to mRNA or scanning. eIF4B is a cofactor for eIF4A but might also function independently of eIF4A. Ribosome profiling of mutants lacking eIF4B or with impaired eIF4A or Ded1 activity revealed that eliminating eIF4B reduces the relative translational efficiencies of many more genes than does inactivation of eIF4A, despite comparable reductions in bulk translation, and few genes display unusually strong requirements for both factors. However, either eliminating eIF4B or inactivating eIF4A preferentially impacts mRNAs with longer, more structured 5’UTRs. These findings reveal an eIF4A-independent role for eIF4B in addition to its function as eIF4A cofactor in promoting PIC attachment or scanning on structured mRNAs. eIF4B, eIF4A, and Ded1 mutations also preferentially impair translation of longer mRNAs in a fashion mitigated by the ability to form closed-loop mRNPs via eIF4F-Pab1 association, suggesting cooperation between closed-loop assembly and eIF4B/helicase functions. Remarkably, depleting eIF4G, the scaffold subunit of eIF4F, preferentially impacts short mRNAs with strong closed-loop potential and unstructured 5’UTRs, exactly the opposite features associated with hyperdependence on the eIF4B/helicases. We propose that short, highly efficient mRNAs preferentially depend on the stimulatory effects of eIF4G-dependent closed-loop assembly.
2016-05-27 | GSE81966 | GEO
Project description:The translational control of oncoprotein expression is implicated in many cancers. Here we report an eIF4A/DDX2 RNA helicase-dependent mechanism of translational control that contributes to oncogenesis and underlies the anticancer effects of Silvestrol and related compounds. For example, eIF4A promotes T-ALL development in vivo and is required for leukaemia maintenance. Accordingly, inhibition of eIF4A with Silvestrol has powerful therapeutic effects in vitro and in vivo. We use transcriptome-scale ribosome footprinting to identify the hallmarks of eIF4A-dependent transcripts. These include 5'UTR sequences such as the 12-mer guanine quartet (CGG)4 motif that can form RNA G-quadruplex structures. Notably, among the most eIF4A-dependent and Silvestrol-sensitive transcripts are a number of oncogenes, super-enhancer associated transcription factors, and epigenetic regulators. Hence, the 5'UTRs of selected cancer genes harbour a targetable requirement for the eIF4A RNA helicase. Comparison of ribosome-protected RNA for drug treated and DMSO treated KOPT-K1 cell, two replicates of ribosome-protected RNA sequencing and three replicates of RNA-seq.
2014-07-27 | E-GEOD-56887 | biostudies-arrayexpress