A MYC/GCN2/eIF2alpha negative feedback loop limits protein synthesis to prevent MYC-dependent apoptosis in colorectal cancer
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ABSTRACT:
PROVIDER: PRJNA418238 | ENA |
REPOSITORIES: ENA
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Project description:Tumours depend on altered rates of protein synthesis for growth and survival, suggesting that mechanisms controlling mRNA translation may be exploitable for therapy. Here, we show that loss of APC, which occurs almost universally in colorectal tumours, strongly enhances the dependence on the translation initiation factor eIF2B5. Depletion of eIF2B5 induces an integrated stress response and enhances translation of MYC via an internal ribosomal entry site. This perturbs cellular amino acid and nucleotide pools and strains energy resources and causes MYC-dependent apoptosis. eIF2B5 limits MYC expression and prevents apoptosis in APC-deficient murine and patient-derived organoids and in APC-deficient murine intestinal epithelia in vivo. Conversely, the high MYC levels present in APC-deficient cells induce phosphorylation of eIF2alpha via the GCN2 and PKR kinases. Pharmacological inhibition of GCN2 phenocopies eIF2B5 depletion and has therapeutic efficacy in tumour organoids, demonstrating that a negative MYC/eIF2alpha feedback loop constitutes a targetable vulnerability of colorectal tumours.
2019-11-04 | GSE106858 | GEO
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Project description:In addition to genomic alterations, aberrant changes in post-transcriptional regulation can modify gene function and drive cancer development. RNA-binding proteins (RBPs) are a large class of post-transcriptional regulators that have been increasingly implicated in carcinogenesis. By integrating multi-omics data, we identify LARP1 as one of the most upregulated RBPs in colorectal cancer (CRC), and demonstrate its oncogenic properties. We perform LARP1:RNA interactome profiling and unveil a previously unexplored role for LARP1 in targeting the 3′UTR of oncogenes in CRC. Notably, we identify the proto-oncogenic transcription factor MYC as a key LARP1-regulated target. Our data show that LARP1 positively modulates MYC expression by associating with its 3′UTR. In addition, antisense oligonucleotide-mediated blocking of the interaction between LARP1 and the MYC 3′UTR reduces MYC expression and in vitro CRC growth. Furthermore, a systematic analysis of LARP1:protein interactions reveals IGF2BP3 and YBX1 as LARP1-interacting proteins that also regulate MYC expression and CRC development. Finally, we demonstrate that MYC reciprocally modulates LARP1 expression by targeting its enhancer. In summary, our data reveal a critical, previously uncharacterized role of LARP1 in promoting CRC tumorigenesis, validate its direct regulation of the proto-oncogene MYC, and delineate a model of the positive feedback loop between MYC and LARP1 that promotes CRC growth and development.
2022-03-10 | PXD030215 | Pride
Project description:General control nonderepressible 2 (GCN2) phosphorylates eIF2α, regulating translation in response to nutritional stress. Here, we show that mammalian ribosomes are potent GCN2 activators. Hydrogen/deuterium exchange–mass spectrometry (HDX-MS) showed GCN2 interacting with domain II of the uL10 P-stalk protein. The P-stalk is a uL10/P12/P22 pentameric complex that is part of the ribosomal GTPase-associated center. Recombinant human P-stalk greatly stimulates GCN2. Both domain II of uL10 and the C-terminal tails of P1 and P2 are necessary for maximal GCN2 activation. On actively translating ribosomes, the C-terminal tails of P1 and P2 are sequestered by elongation factors, suggesting P-stalk availability could link translational stress to GCN2 activation.
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Project description:Compared protein synthesis in Gcn2 WT vs Gcn2 KO murine PDAC cells (KRPC) in amino acid-replete or leucine-free media.
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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: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: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.
2024-03-06 | GSE239867 | GEO
Project description:To identify new Gcn2 target proteins, we performed a set of Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC)-based quantitative phosphoproteomics experiments, in which we compared WT cells to gcn2∆ and sui2S52A cells (n=3), all treated, or not, with rapamycin, which has previously been shown to stimulate eIF2alpha phosphorylation by Gcn2.
2021-03-22 | PXD021109 | Pride
Project description:This study was designed to evaluate similarities and differences between transcriptional responses of developing Th17 cells to the prolyl-tRNA synthetase inhibitor, halofuginone, and the mTOR inhibitor, rapamycin. Further comparisons between wild-type and Gcn2-/- Th17 cells allow for investigation into which gene modules regulated by halofuginone or rapamycin treatment require Gcn2. Murine CD4+ CD25- T cells were magnetically isolated from wild-type or Gcn2-/- T cells. These cells were activated through anti-CD3/ anti-CD28 antibodies and polarized into Th17 cells using TGFb plus IL-6. 10 nM halofuginone, 10 nM rapamycin, or vehicle control (DMSO) were added to cultures at the time of activation. Cells were harvested at 4, 18, or 72 hours post-activation and differentiation. RNA was isolated from each sample and used for microarray analysis. Each culture condition and time-point was repeated twice in independent experiments using cells isolated from different wild-type or Gcn2-/- mice. Vehicle versus halofuginone, vehicle versus rapamycin, halofuginone versus rapamycin. Gcn2-/- versus wild-type T cells treated with vehicle, halofuginone, or rapamycin.
2014-05-29 | E-GEOD-47478 | biostudies-arrayexpress