Translation elongation factor 2 depletion by siRNA in mouse liver leads to mTOR-independent translational upregulation of ribosomal protein genes
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ABSTRACT:
PROVIDER: PRJNA561206 | ENA |
REPOSITORIES: ENA
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Project description:Due to breakthroughs in RNAi and genome editing methods in the past decade, it is now easier than ever to study fine details of protein synthesis in animal models. However, most of our understanding of translation comes from unicellular organisms and cultured mammalian cells. In this study, we demonstrate the feasibility of perturbing protein synthesis in a mouse liver by targeting translation elongation factor 2 (eEF2) with RNAi. We were able to achieve over 90% knockdown efficacy and maintain it for 2 weeks effectively slowing down the rate of translation elongation. As the total protein yield declined, both proteomics and ribosome profiling assays showed robust translational upregulation of ribosomal proteins relative to other proteins. Although all these genes bear the TOP regulatory motif, the branch of the mTOR pathway responsible for translation regulation was not activated. Paradoxically, coordinated translational upregulation of ribosomal proteins only occurred in the liver but not in murine cell culture. Thus, the upregulation of ribosomal transcripts likely occurred via passive mTOR-independent mechanisms. Impaired elongation sequesters ribosomes on mRNA and creates a shortage of free ribosomes. This leads to preferential translation of transcripts with high initiation rates such as ribosomal proteins. Furthermore, severe eEF2 shortage reduces the negative impact of positively charged amino acids frequent in ribosomal proteins on ribosome progression.
2020-05-31 | GSE136091 | GEO
Project description: Not available
| S-EPMC7511953 | biostudies-literature
Project description:The PI3K-Akt-mTOR signaling pathway is a master regulator of RNA translation. Pharmacological inhibition of this pathway preferentially and coordinately suppresses, in a 4EBP1/2-dependent manner, translation of mRNAs encoding ribosomal proteins. However, it remains unclear whether mTOR-4EBP1/2 is the exclusive translational regulator of this group of genes, and furthermore, systematic searches for novel translational modulators have been immensely challenging due to difficulties in scaling existing RNA translation profiling assays. Here, we developed a rapid and highly scalable approach for gene-specific quantitation of RNA translation, termed Targeted Profiling of RNA Translation (TPRT). We applied this technique in a chemical screen for novel translational modulators, and identified numerous preclinical and clinical therapeutic compounds, with diverse nominal targets, that preferentially suppress translation of ribosomal proteins. Surprisingly, some of these compounds act in a manner that bypasses canonical regulation by mTOR-4EBP1/2. Instead, these compounds exert their translational effects in a manner that is dependent upon GCN2-eIF2α, a central signaling axis within the integrated stress response. Furthermore, we were also able to identify metabolic perturbations that also suppress ribosomal protein translation in an mTOR-independent manner. Together, we describe a novel translational assay that is directly applicable to large-scale RNA translation studies, and that enabled us to identify a non-canonical, mTOR-independent mode for translational regulation of ribosomal proteins.
2018-09-21 | GSE118422 | GEO
Project description:The mammalian target of rapamycin (mTOR) kinase is a master regulator of protein synthesis that couples nutrient sensing to cell growth and cancer. However, the downstream translationally regulated nodes of gene expression that may direct cancer development are poorly characterized. Employing ribosome profiling we uncover specialized translation of the prostate cancer genome by oncogenic mTOR signaling, revealing a remarkably specific repertoire of genes involved in cell proliferation, metabolism, and invasion. We extend these findings by functionally characterizing a class of translationally controlled pro-invasion mRNAs that we show direct prostate cancer invasion and metastasis downstream of oncogenic mTOR signaling. We further develop a clinically relevant ATP site inhibitor of mTOR, INK128, which reprograms this gene expression signature with therapeutic benefit for prostate cancer metastasis, for which there is presently no cure. Together, these findings significantly extend our understanding of how the M-bM-^@M-^\cancerousM-bM-^@M-^] translation machinery steers specific cancer cell behaviors and may be therapeutically targeted. Examination of mRNA translation in human prostate cancer upon differential inhibition of the mTOR signaling pathway.
2012-02-28 | E-GEOD-35469 | biostudies-arrayexpress
Project description:Type-I interferon (IFN)-induced activation of the mammalian target of rapamycin (mTOR) signaling pathway has been implicated in translational control of mRNAs encoding interferon-stimulated genes (ISGs). However, mTOR-sensitive translatomes commonly include mRNAs with a 5’ terminal oligopyrimidine tract (TOP), such as those encoding ribosomal proteins, but not ISGs. Because these translatomes were obtained under conditions when ISG expression is not induced, we examined the mTOR-sensitive translatome in human WISH cells stimulated with IFNβ. The mTOR inhibitor Torin1 resulted in a repression of global protein synthesis, including that of ISG products, and translation of all but 3 ISG mRNAs (TLR3, NT5C3A, and RNF19B) was not selectively more sensitive to mTOR inhibition. Detailed studies of NT5C3A revealed an IFN-induced change in transcription start site resulting in a switch from a non-TOP to a TOP-like transcript variant and mTOR sensitive translation. Thus, we show that, in the cell model used, translation of the vast majority of ISG mRNAs is not selectively sensitive to mTOR activity and describe an uncharacterized mechanism wherein the 5’-UTR of an mRNA is altered in response to a cytokine, resulting in a shift from mTOR-insensitive to mTOR-sensitive translation.
2015-07-07 | GSE70270 | GEO
Project description:Pancreatic ductal adenocarcinoma (PDAC) relies on hyper-activated protein synthesis. Consistently, human and mouse PDAC lose expression of the translational repressor and mTOR target 4E-BP1. Using genome-wide polysome-profiling, we here explore mRNAs whose translational efficiencies depend on the mTOR/4E-BP1 axis in Miapaca-2 cells. This was performed by isolating cytoplasmic and efficiently translated (heavy polysome-associated) mRNAs from MiaPaca-2 cells upon PP242-mediated mTOR inhibition
2019-09-18 | GSE137553 | GEO
Project description:The mammalian target of rapamycin (mTOR) kinase is a master regulator of protein synthesis that couples nutrient sensing to cell growth and cancer. However, the downstream translationally regulated nodes of gene expression that may direct cancer development are poorly characterized. Employing ribosome profiling we uncover specialized translation of the prostate cancer genome by oncogenic mTOR signaling, revealing a remarkably specific repertoire of genes involved in cell proliferation, metabolism, and invasion. We extend these findings by functionally characterizing a class of translationally controlled pro-invasion mRNAs that we show direct prostate cancer invasion and metastasis downstream of oncogenic mTOR signaling. We further develop a clinically relevant ATP site inhibitor of mTOR, INK128, which reprograms this gene expression signature with therapeutic benefit for prostate cancer metastasis, for which there is presently no cure. Together, these findings significantly extend our understanding of how the “cancerous” translation machinery steers specific cancer cell behaviors and may be therapeutically targeted.
2012-02-28 | GSE35469 | GEO
Project description:We leverage a model statistical framework coupled with high resoluation ribosome profiling data to produce robust estimates of per-codon elongation rates in yeast.
2018-08-18 | GSE102837 | GEO
