Ontology highlight
ABSTRACT:
PROVIDER: PRJNA579144 | ENA |
REPOSITORIES: ENA
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Project description:Translational control is a key determinant of protein abundance, which in turns defines the physiology and pathology of human cells. Initiation of translation is highly regulated in eukaryotes and is considered as the rate-limiting step of protein synthesis. mRNA secondary structures in 5’ untranslated region (UTR) and associated helicases have been characterised as key determinants of translation initiation. Nevertheless the transcriptome-wide contribution of non-canonical secondary structures, such as RNA G-quadruplexes (rG4s), to the translation of human mRNAs remains largely unappreciated. Here we use a ribosome profiling strategy to investigate the translational landscape associated to rG4s-containing mRNAs and the contribution of two rG4s-specialised DExH-box helicases, DHX9 and DHX36, to translation initiation in human cells. We show that rG4-forming sequences in 5’-UTR is associated with decreased translation efficiency which correlate with an increased ribosome density within the 5’-UTRs. We found that rG4s contribute to the translation of upstream open reading frames, and as a consequence, thwart the translation of the associated protein coding sequences (CDS). Depletion of the DHX36 and DHX9 helicases demonstrated that the formation of the rG4 structural motif rather than its nucleotide sequence mediate translation initiation. Our findings unveil a role for non-canonical structures in defining alternative 5’ starts for human mRNAs translation initiation.
2018-04-30 | GSE105082 | GEO
Project description:Messenger RNA acts as an informational molecule between DNA and translating ribosomes. Emerging evidence places mRNA in central cellular processes beyond its major function as informational entity. Although individual examples show that specific structural features of mRNA regulate translation and transcript stability, their role and function throughout the bacterial transcriptome remains unknown. Combining three sequencing approaches to provide a high resolution view of global mRNA secondary structure, translation efficiency and mRNA abundance, we unraveled structural features in E. coli mRNA with implications in translation and mRNA degradation. A poorly structured site upstream of the coding sequence serves as an additional unspecific binding site of the ribosomes and the degree of its secondary structure propensity negatively correlates with gene expression. Secondary structures within coding sequences are highly dynamic and influence translation only within a very small subset of positions. A secondary structure upstream of the stop codon is enriched in genes terminated by UAA codon with likely implications in translation termination. The global analysis further substantiates a common recognition signature of RNase E to initiate endonucleolytic cleavage. This work determines for the first time the E. coli RNA structurome, highlighting the contribution of mRNA secondary structure as a direct effector of a variety of processes, including translation and mRNA degradation.
2015-10-21 | GSE63817 | GEO
Project description:Protein concentrations evolve under greater evolutionary constraint than mRNA levels. In addition, translation efficiency of mRNA populations represents the chief determinant of basal protein concentrations. This raises a fundamental question as to how mRNA and protein levels are actively coordinated in dynamic systems responding to acute physiological stimuli. This report examines the contributions of mRNA abundance and translation efficiency to protein output in cells responding to oxygen stimulus. We show that alternative translation efficiencies, not mRNA levels, represent the major adaptive mechanism that governs the cellular response to perturbations in [O2]. This phenomenon is coordinated by eIF4F under atmospheric [O2] and the previously uncharacterized hypoxic eIF4F (eIF4FH) under low [O2]. The oxygen-regulated remodeling of translation efficiency enables oxygenated and hypoxic cells to produce surprisingly divergent translatomes of similar complexity, with minimal dependence on mRNA levels. Changes in mRNA concentrations observed between normoxic and hypoxic cells are likely neutral, as they are during evolution. We propose that mRNAs contain hard-wired translation efficiency determinants for their triage by the translation apparatus on [O2] stimulus.
2016-07-20 | MSV000079962 | MassIVE
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naïve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naïve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naïve pluripotent state, and subsequently undergo aberrant priming and early lineage commitment at the post-implantation stage. A comprehensive functional and genomic analysis involving profiling of m6A, RNA transcription and translation in Mettl3 wild-type and knockout pluripotent and differentiated cells, identified m6A as a critical determinant that destabilizes secondary naïve specific pluripotency genes Esrrb, Klf4 and Nanog, and restrains their transcript stability and translation efficiency. In summary, our findings provide for the first time evidence for a critical role for an mRNA epigenetic modification in early mammalian development in vivo, and identify a mechanism that functionally regulates mouse naïve and primed pluripotency in an opposing manner. Ribosome footprint (Ribo-Seq) was measured from mouse embryonic stem cells and mouse embriod bodies, in WT and Mettl3-KO cell lines.
2014-11-02 | E-GEOD-61996 | biostudies-arrayexpress
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naM-CM-/ve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naM-CM-/ve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naM-CM-/ve pluripotent state, and subsequently undergo aberrant priming and early lineage commitment at the post-implantation stage. A comprehensive functional and genomic analysis involving profiling of m6A, RNA transcription and translation in Mettl3 wild-type and knockout pluripotent and differentiated cells, identified m6A as a critical determinant that destabilizes secondary naM-CM-/ve specific pluripotency genes Esrrb, Klf4 and Nanog, and restrains their transcript stability and translation efficiency. In summary, our findings provide for the first time evidence for a critical role for an mRNA epigenetic modification in early mammalian development in vivo, and identify a mechanism that functionally regulates mouse naM-CM-/ve and primed pluripotency in an opposing manner. 3' polyA RNA-sequencing (equivalent to Digital Gene Expression) measured in mouse Embryonic Stem Cells (ESCs) and mouse Embriod bodies (EBs) 0,4 & 8 hours after treatment with Actinomycin which halts transcription. Measured in both WT and Mettl3-KO cells.
2014-11-02 | E-GEOD-61994 | biostudies-arrayexpress
Project description:Protein concentrations evolve under greater evolutionary constraint than mRNA levels. In addition, translation efficiency of mRNA populations represents the chief determinant of basal protein concentrations. This raises a fundamental question as to how mRNA and protein levels are actively coordinated in dynamic systems responding to acute physiological stimuli. This report examines the contributions of mRNA abundance and translation efficiency to protein output in cells responding to oxygen stimulus. We show that alternative translation efficiencies, not mRNA levels, represent the major adaptive mechanism that governs the cellular response to perturbations in [O2]. This phenomenon is coordinated by eIF4F under atmospheric [O2] and the previously uncharacterized hypoxic eIF4F (eIF4FH) under low [O2]. The oxygen-regulated remodeling of translation efficiency enables oxygenated and hypoxic cells to produce surprisingly divergent translatomes of similar complexity, with minimal dependence on mRNA levels. Changes in mRNA concentrations observed between normoxic and hypoxic cells are likely neutral, as they are during evolution. We propose that mRNAs contain hard-wired translation efficiency determinants for their triage by the translation apparatus on [O2] stimulus.
2016-02-05 | PXD003037 | Pride
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:Understanding the physiological relevance of structures in mammalian mRNAs remains elusive, especially considering the global unfolding of mRNA structures in eukaryotic organisms recently examined, as well as the decade-long observation that mRNAs generally seem no more likely than random sequences to be stably folded. Here we show that RNA secondary structures, mostly weak and close-to-random, facilitate the 3′-end processing of thousands of human mRNAs by juxtaposing poly(A) signals (PASs) and cleavage sites that are otherwise too far apart. Folding of these 3′-end structures also enhances mRNA stability. Global structure probing shows that 3′-end regions are indeed folded in cells despite substantial unfolding of PAS-upstream regions. Analyses of thousands of ectopically expressed variants prove that folding both enhances processing and increases stability. Mutagenesis of a genomic locus further implicates structure-controlled processing in regulating neighboring gene expression. These results reveal widespread roles for RNA structure in mammalian mRNA biogenesis and metabolism.
2017-03-12 | GSE93424 | GEO
Project description:Understanding the physiological relevance of structures in mammalian mRNAs remains elusive, especially considering the global unfolding of mRNA structures in eukaryotic organisms recently examined, as well as the decade-long observation that mRNAs generally seem no more likely than random sequences to be stably folded. Here we show that RNA secondary structures, mostly weak and close-to-random, facilitate the 3′-end processing of thousands of human mRNAs by juxtaposing poly(A) signals (PASs) and cleavage sites that are otherwise too far apart. Folding of these 3′-end structures also enhances mRNA stability. Global structure probing shows that 3′-end regions are indeed folded in cells despite substantial unfolding of PAS-upstream regions. Analyses of thousands of ectopically expressed variants prove that folding both enhances processing and increases stability. Mutagenesis of a genomic locus further implicates structure-controlled processing in regulating neighboring gene expression. These results reveal widespread roles for RNA structure in mammalian mRNA biogenesis and metabolism.
2017-03-12 | GSE95467 | GEO
Project description:Understanding the physiological relevance of structures in mammalian mRNAs remains elusive, especially considering the global unfolding of mRNA structures in eukaryotic organisms recently examined, as well as the decade-long observation that mRNAs generally seem no more likely than random sequences to be stably folded. Here we show that RNA secondary structures, mostly weak and close-to-random, facilitate the 3′-end processing of thousands of human mRNAs by juxtaposing poly(A) signals (PASs) and cleavage sites that are otherwise too far apart. Folding of these 3′-end structures also enhances mRNA stability. Global structure probing shows that 3′-end regions are indeed folded in cells despite substantial unfolding of PAS-upstream regions. Analyses of thousands of ectopically expressed variants prove that folding both enhances processing and increases stability. Mutagenesis of a genomic locus further implicates structure-controlled processing in regulating neighboring gene expression. These results reveal widespread roles for RNA structure in mammalian mRNA biogenesis and metabolism.
2017-03-12 | GSE95466 | GEO