Multiple mechanisms activate GCN2 eIF2 kinase in response to diverse stress conditions
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PROVIDER: PRJNA1001302 | ENA |
REPOSITORIES: ENA
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Project description:Diverse environmental insults induce the integrated stress response (ISR), which features eIF2 phosphorylation and translational control that serves to restore protein homeostasis. The eIF2 kinase GCN2 is a first responder in the ISR that is activated by amino acid depletion and other unrelated stresses. Two processes are suggested to trigger an ordered process of GCN2 activation during stress: GCN2 monitoring stress via accumulating uncharged tRNAs or by stalled and colliding ribosomes. Our results suggest that while ribosomal collisions are indeed essential for GCN2 activation in response to translational elongation inhibitors, conditions that trigger deacylation of tRNAs activate GCN2 via its direct association with affected tRNAs. Both process require the GCN2 regulatory domain related to histidyl tRNA synthetases. GCN2 activation by UV irradiation features lowered amino acids and increased uncharged tRNAs and ribosome collisions are dispensable. We conclude that there are multiple mechanisms that activate GCN2 during diverse stresses.
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Project description:When eukaryotic cells are deprived of amino acids, uncharged tRNAs accumulate and activate the conserved GCN2 protein kinase. We examine how yeast growth and tRNA charging or aminoacylation is affected during amino acid depletion in the presence and absence of GCN2. tRNA charging is measured using a microarray technique which allows for simultaneous measurement of all cytosolic tRNAs. A fully prototrophic and its isogenic GCN2 deletion strain were used. We measured relative tRNA charging levels in yeast strains with an intact and deleted GCN2.
2010-08-01 | E-GEOD-22452 | biostudies-arrayexpress
Project description:When eukaryotic cells are deprived of amino acids, uncharged tRNAs accumulate and activate the conserved GCN2 protein kinase. We examine how yeast growth and tRNA charging or aminoacylation is affected during amino acid depletion in the presence and absence of GCN2. tRNA charging is measured using a microarray technique which allows for simultaneous measurement of all cytosolic tRNAs. A fully prototrophic and its isogenic GCN2 deletion strain were used.
2010-08-01 | GSE22452 | GEO
Project description:Discordant regulation of eIF2 kinase GCN2 and mTORC1 during nutrient stress
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Project description:Cancers invoke response pathways to mitigate external and internal stresses to aid growth and proliferation. For example, we reported that GCN2 eIF2 kinase and the Integrated Stress Response are constitutively active in prostate cancer (PCa) and are required to maintain amino acid homeostasis needed to fuel tumor growth. However, while genetic or pharmacological loss of GCN2 lowers intracellular amino acids and deters PCa growth, there does not appear to be appreciable cell death. Using biochemical and molecular approaches, RNA-seq and CRISPRi-based screens, along with in vitro and in vivo PCa models, we discovered that the loss of GCN2 in PCa induces p53 signaling and tumor senescence. Activation of p53 occurs by reductions in purine nucleobases and lowered rRNA synthesis that induce the Impaired Ribosome Biogenesis Checkpoint. Loss of GCN2 combined with depletion of p53 or pharmacological inhibition of de novo purine biosynthesis with the GART inhibitor pelitrexol sharply reduces PCa growth and triggers apoptosis, emphasizing the importance of coordinated GCN2 and p53 regulation and their utility in PCa therapeutics.
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Project description:Here we report Total RNA seq and RiboSeq on MEF cells treated with halofuginone. Halofuginone is a competitive inhibitor of the Prolyl-tRNA synthetase that results in an accumulation of uncharged Prolyl-tRNA upon treatment that leads to an activation of the protein kinase Gcn2.
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Project description:Here we report total RNA seq on wounded and unwounded NTERT WT and GCN2 KO cells.
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Project description:In response to different cellular stressors, the ISR kinases, PERK, PKR, HRI and GCN2, activate downstream transcriptional programs. While the core ISR transcription program is well characterized, markers that are specific to each individual ISR kinase activation pathway are not known. To identify markers that are induced by PERK or GCN2, but not the other ISR kinases, we subjected WT, GCN2-/-, and PERK-/- MEFs to amino acid starvation (RPMI 1640 SILAC -Lys -Arg) or Thapsigargin (200nM) treatment for 6 hours to activate the GCN2 and PERK pathways, respectively and performed RNA sequencing.
2022-07-01 | GSE179559 | GEO
Project description:In eukaryotes, regulation of mRNA translation enables a fast, localized and finely tuned expression of gene products. Within the translation process, the first stage of translation initiation is most rigorously modulated by the actions of eukaryotic initiation factors (eIFs) and their associated proteins. These 11 eIFs catalyze the joining of the tRNA, mRNA and rRNA into a functional translation complex. Their activity is influenced by a wide variety of extra- and intracellular signals, ranging from global, such as hormone signaling and unfolded proteins, to specific, such as single amino acid imbalance and iron deficiency. Their action is correspondingly comprehensive, in increasing or decreasing recruitment and translation of most cellular mRNAs, and specialized, in targeting translation of mRNAs with regulatory features such as a 5’ terminal oligopyrimidine tract (TOP), upstream open reading frames (uORFs), or an internal ribosomal entry site (IRES). In mammals, two major pathways are linked to targeted mRNA translation. The target of rapamycin (TOR) kinase induces translation of TOP and perhaps other subsets of mRNAs, whereas a family of eIF2 kinases does so with mRNAs containing uORFs or an IRES. TOR targets translation of mRNAs that code for proteins involved in translation, an action compatible with its widely accepted role in regulating cellular growth. The four members of the eIF2 kinase family increase translation of mRNAs coding for stress response proteins such as transcription factors and chaperones. Though all four kinases act on one main substrate, eIF2, published literature demonstrates both common and unique effects by each kinase in response to its specific activating stress. This suggests that the activated eIF2 kinases regulate the translation of both a global and a specific set of mRNAs. Up to now, few studies have attempted to test such a hypothesis; none has been done in mammals. We use array analysis to determine the global mRNA shift into polysomes following a stress response, and to compare the translational response following activation of GCN2 versus PERK, two of the four eIF2alpha kinases. Experiment Overall Design: Gcn2 wild-type or knockout mouse liver were perfused with complete amino acids media or media lacking methionine for RNA extraction and hybridization of Affymetrix microarrays. RNA was extracted from unfractionated liver samples and polysome fraction of samples separated on sucrose density gradient. To minimize biological variations, we pooled RNA from two perfused liver samples to use in each array analysis. The conditions were total and polysome fraction of Gcn2+/+, +Met or -Met; total and polysome fraction of Gcn2-/-, +Met or -Met. Each array analysis was done in duplicate.
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Project description:Coordination between GCN2 eIF2 kinase and p53 signaling supports purine metabolism and enhances growth and progression of prostate cancer
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