Translation in amino acid-poor environments is limited by tRNAGln charging
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PROVIDER: PRJNA660742 | ENA |
REPOSITORIES: ENA
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Project description:An inadequate supply of amino acids leads to accumulation of uncharged tRNAs, which can bind and activate GCN2 kinase to reduce translation. Here, we show that glutamine-specific tRNAs selectively become uncharged when extracellular amino acid availability is compromised. In contrast, all other tRNAs retain charging of their cognate amino acids in a manner that is dependent upon intact lysosomal function. In addition to GCN2 activation and reduced total translation, the reduced charging of tRNAGln in amino acid-deprived cells also leads to specific depletion of proteins containing polyglutamine tracts including core binding factor α1, mediator subunit 12, transcriptional coactivator CBP and TATA-box binding protein. Treating amino acid-deprived cells with exogenous glutamine or glutaminase inhibitors restores tRNAGln charging and the levels of polyglutamine-containing proteins. Together, these results demonstrate that the activation of GCN2 and the translation of polyglutamine-encoding transcripts serve as the key sensors of glutamine availability in mammalian cells.
2020-12-14 | GSE157276 | GEO
Project description: Not available
| S-EPMC7744096 | biostudies-literature
Project description:One of the central goals of evolutionary biology is to explain and predict the molecular basis of adaptive evolution. We studied the evolution of genetic networks in Saccharomyces cerevisiae (budding yeast) populations propagated for more than 200 generations in different nitrogen-limiting conditions. We find that rapid adaptive evolution in nitrogen-poor environments is dominated by the de novo generation and selection of copy number variants (CNVs), a large fraction of which contain genes encoding specific nitrogen transporters including PUT4, DUR3 and DAL4. The large fitness increases associated with these alleles limits the genetic heterogeneity of adapting populations even in environments with multiple nitrogen sources. Complete identification of acquired point mutations, in individual lineages and entire populations, identified heterogeneity at the level of genetic loci but common themes at the level of functional modules, including genes controlling phosphatidylinositol-3-phosphate metabolism and vacuole biogenesis. Adaptive strategies shared with other nutrient-limited environments point to selection of genetic variation in the TORC1 and Ras/PKA signaling pathways as a general mechanism underlying improved growth in nutrient-limited environments. Within a single population we observed the repeated independent selection of a multi-locus genotype, comprised of the functionally related genes GAT1, MEP2 and LST4. By studying the fitness of individual alleles, and their combination, as well as the evolutionary history of the evolving population, we find that the order in which these mutations are acquired is constrained by epistasis. The identification of repeatedly selected variation at functionally related loci that interact epistatically suggests that gene network polymorphisms (GNPs) may be a frequent outcome of adaptive evolution. Our results provide insight into the mechanistic basis by which cells adapt to nutrient-limited environments and suggest that knowledge of the selective environment and the regulatory mechanisms important for growth and survival in that environment greatly increases the predictability of adaptive evolution. mRNA from each evolved clone or from the ancestral strain growing in the specificied nitrogen-limited condition was co-hybridized with mRNA from the ancestral strain grown in ammonium limited media
2013-11-28 | E-GEOD-52786 | biostudies-arrayexpress
Project description:One of the central goals of evolutionary biology is to explain and predict the molecular basis of adaptive evolution. We studied the evolution of genetic networks in Saccharomyces cerevisiae (budding yeast) populations propagated for more than 200 generations in different nitrogen-limiting conditions. We find that rapid adaptive evolution in nitrogen-poor environments is dominated by the de novo generation and selection of copy number variants (CNVs), a large fraction of which contain genes encoding specific nitrogen transporters including PUT4, DUR3 and DAL4. The large fitness increases associated with these alleles limits the genetic heterogeneity of adapting populations even in environments with multiple nitrogen sources. Complete identification of acquired point mutations, in individual lineages and entire populations, identified heterogeneity at the level of genetic loci but common themes at the level of functional modules, including genes controlling phosphatidylinositol-3-phosphate metabolism and vacuole biogenesis. Adaptive strategies shared with other nutrient-limited environments point to selection of genetic variation in the TORC1 and Ras/PKA signaling pathways as a general mechanism underlying improved growth in nutrient-limited environments. Within a single population we observed the repeated independent selection of a multi-locus genotype, comprised of the functionally related genes GAT1, MEP2 and LST4. By studying the fitness of individual alleles, and their combination, as well as the evolutionary history of the evolving population, we find that the order in which these mutations are acquired is constrained by epistasis. The identification of repeatedly selected variation at functionally related loci that interact epistatically suggests that gene network polymorphisms (GNPs) may be a frequent outcome of adaptive evolution. Our results provide insight into the mechanistic basis by which cells adapt to nutrient-limited environments and suggest that knowledge of the selective environment and the regulatory mechanisms important for growth and survival in that environment greatly increases the predictability of adaptive evolution. DNA from each evolved clone or population is hybridized vs DNA from the ancestral strain
2013-11-28 | E-GEOD-52696 | biostudies-arrayexpress
Project description:One of the central goals of evolutionary biology is to explain and predict the molecular basis of adaptive evolution. We studied the evolution of genetic networks in Saccharomyces cerevisiae (budding yeast) populations propagated for more than 200 generations in different nitrogen-limiting conditions. We find that rapid adaptive evolution in nitrogen-poor environments is dominated by the de novo generation and selection of copy number variants (CNVs), a large fraction of which contain genes encoding specific nitrogen transporters including PUT4, DUR3 and DAL4. The large fitness increases associated with these alleles limits the genetic heterogeneity of adapting populations even in environments with multiple nitrogen sources. Complete identification of acquired point mutations, in individual lineages and entire populations, identified heterogeneity at the level of genetic loci but common themes at the level of functional modules, including genes controlling phosphatidylinositol-3-phosphate metabolism and vacuole biogenesis. Adaptive strategies shared with other nutrient-limited environments point to selection of genetic variation in the TORC1 and Ras/PKA signaling pathways as a general mechanism underlying improved growth in nutrient-limited environments. Within a single population we observed the repeated independent selection of a multi-locus genotype, comprised of the functionally related genes GAT1, MEP2 and LST4. By studying the fitness of individual alleles, and their combination, as well as the evolutionary history of the evolving population, we find that the order in which these mutations are acquired is constrained by epistasis. The identification of repeatedly selected variation at functionally related loci that interact epistatically suggests that gene network polymorphisms (GNPs) may be a frequent outcome of adaptive evolution. Our results provide insight into the mechanistic basis by which cells adapt to nutrient-limited environments and suggest that knowledge of the selective environment and the regulatory mechanisms important for growth and survival in that environment greatly increases the predictability of adaptive evolution.
2013-11-28 | GSE52786 | GEO
Project description:One of the central goals of evolutionary biology is to explain and predict the molecular basis of adaptive evolution. We studied the evolution of genetic networks in Saccharomyces cerevisiae (budding yeast) populations propagated for more than 200 generations in different nitrogen-limiting conditions. We find that rapid adaptive evolution in nitrogen-poor environments is dominated by the de novo generation and selection of copy number variants (CNVs), a large fraction of which contain genes encoding specific nitrogen transporters including PUT4, DUR3 and DAL4. The large fitness increases associated with these alleles limits the genetic heterogeneity of adapting populations even in environments with multiple nitrogen sources. Complete identification of acquired point mutations, in individual lineages and entire populations, identified heterogeneity at the level of genetic loci but common themes at the level of functional modules, including genes controlling phosphatidylinositol-3-phosphate metabolism and vacuole biogenesis. Adaptive strategies shared with other nutrient-limited environments point to selection of genetic variation in the TORC1 and Ras/PKA signaling pathways as a general mechanism underlying improved growth in nutrient-limited environments. Within a single population we observed the repeated independent selection of a multi-locus genotype, comprised of the functionally related genes GAT1, MEP2 and LST4. By studying the fitness of individual alleles, and their combination, as well as the evolutionary history of the evolving population, we find that the order in which these mutations are acquired is constrained by epistasis. The identification of repeatedly selected variation at functionally related loci that interact epistatically suggests that gene network polymorphisms (GNPs) may be a frequent outcome of adaptive evolution. Our results provide insight into the mechanistic basis by which cells adapt to nutrient-limited environments and suggest that knowledge of the selective environment and the regulatory mechanisms important for growth and survival in that environment greatly increases the predictability of adaptive evolution.
2013-11-28 | GSE52696 | GEO
Project description:Amino acid availability regulates translation through the action of the GCN2 and mTORC1 pathways. Low amino acids activate the eIF2α kinase GCN2 through binding of uncharged tRNAs to a histidyl-tRNA synthetase−related regulatory domain. Once activated GCN2 phosphorylates eIF2α, inhibiting ternary complex formation and translation initiation. Recent studies show that mTORC1 is particularly sensitive to arginine and leucine status, with a deprivation of these amino acids leading to a strong inhibition of mTORC1 that prevents the phosphorylation and inactivation of the translational repressor 4EBP1. Though amino acids are known regulators of translation, the effects that deficiencies of specific amino acids have on translation have yet to be determined. We demonstrate that deprivation of leucine or methionine results in large inhibitory effects on translation initiation and on polysome formation that are not replicated by overexpressing non-phosphorylatable 4EBP1 or a phosphomimetic eIF2α. Our results demonstrate that a lack of either leucine or methionine has a major impact on mRNA translation, though they act by quite different mechanisms. Leucine deprivation appears to primarily inhibit ribosome loading, whereas methionine deprivation appears to primarily impair start site recognition. These data point to a unique regulatory effect that methionine status has on translation initiation.
2018-04-04 | GSE112643 | GEO
Project description:Recent observations about how cells sense amino acids have argued for preeminent roles of mTOR and the stress kinase GCN2 in allowing cells to estimate their amino acid needs. Here we used models of programmed immune microenvironments where helper T cells have to sense how much amino acids are available to engage in antigen-fueled proliferation. Contrary to current models, T cells activate mTOR in the competency phase of the cell cycle regardless of amino acid amounts, GCN2 or surface TCR. Instead, we found T cells use an amino acid sensing system to target IL-2-induced STAT5 phosphorylation at the restriction point of cell cycle commitment. mTOR activity is subsequently reduced and specifically connected to SREBP activation. T cells can be pushed into cycle by increasing IL-2 even when no amino acids are available. Collectively, our studies reveal helper T cells use sequential and distinct pathways to measure local amino acid concentrations.
2016-11-02 | GSE68804 | GEO
Project description:Protein synthesis is metabolically costly, and the level of translation must match nutrient availability and cellular needs. Overall protein synthesis levels are modulated by regulating translation initiation. The cap-binding protein eIF4E—the earliest contact between mRNAs and the translation machinery—serves as one point of control, but its contributions to mRNA-specific translation regulation remain poorly understood. We acutely depleted eIF4E, which is essential in budding yeast, and observed surprisingly modest effects on cell growth and protein synthesis. Long-lived transcripts were downregulated, likely reflecting accelerated turnover, and the strongest gene-specific effects arose as secondary effects of reduced protein biosynthesis on amino acid pools. Futile cycles of amino acid synthesis and degradation were accompanied by translational activation of GCN4, which is typically induced by amino acid starvation. We further identified translational tuning of PCL5, a negative regulator of Gcn4, that provides a consistent protein-to-mRNA ratio under varying translation environments. This translational control depended in part on a uniquely long poly-(A) tract in the PCL5 5’ UTR and on poly-(A) binding protein. These results highlight the intricate interplay between translation, amino acid homeostasis, and gene regulation and uncover new layers of feedback control in cellular response to stress and nutrient availability.
2023-05-09 | GSE231756 | GEO
Project description:Protein synthesis is metabolically costly, and the level of translation must match nutrient availability and cellular needs. Overall protein synthesis levels are modulated by regulating translation initiation. The cap-binding protein eIF4E—the earliest contact between mRNAs and the translation machinery—serves as one point of control, but its contributions to mRNA-specific translation regulation remain poorly understood. We acutely depleted eIF4E, which is essential in budding yeast, and observed surprisingly modest effects on cell growth and protein synthesis. Long-lived transcripts were downregulated, likely reflecting accelerated turnover, and the strongest gene-specific effects arose as secondary effects of reduced protein biosynthesis on amino acid pools. Futile cycles of amino acid synthesis and degradation were accompanied by translational activation of GCN4, which is typically induced by amino acid starvation. We further identified translational tuning of PCL5, a negative regulator of Gcn4, that provides a consistent protein-to-mRNA ratio under varying translation environments. This translational control depended in part on a uniquely long poly-(A) tract in the PCL5 5’ UTR and on poly-(A) binding protein. These results highlight the intricate interplay between translation, amino acid homeostasis, and gene regulation and uncover new layers of feedback control in cellular response to stress and nutrient availability.
2023-05-09 | GSE231757 | GEO