Homo sapiens
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ABSTRACT:
PROVIDER: PRJDB13735 | ENA |
REPOSITORIES: ENA
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Project description:The mechanistic target of rapamycin complex 1 (mTORC1) is involved in nutrient-induced signaling and is a master regulator of cell growth and metabolism. Amino acid-deficient conditions affect mTORC1 activity; however, its upstream regulators warrant further investigation. MicroRNAs are key regulators of nutrient-related responses; therefore, the present study aimed to assess the leucine starvation-induced microRNA profile and its impact on mTORC1 activity. Transcriptome analysis of human hepatocellular carcinoma cells (HepG2) under leucine deprivation revealed that hsa-miR-663a and hsa-miR-1469 were altered in a transcription factor 4-dependent manner. Overexpression of these microRNAs induced phosphorylation of the ribosomal protein S6 kinase beta-1, a mTORC1 downstream target. Furthermore, hsa-miR-663a downregulated proline-rich Akt1 substrate of 40 kDa (PRAS40), one of the mTORC1 components. In summary, this study provides new insights into the regulatory role of microRNAs in amino acid metabolism and demonstrate alterations in microRNA profile under leucine deprivation in human hepatocytes.
2022-07-15 | GSE208228 | GEO
Project description:We previously demonstrated the proof of concept for the functionality of the NUTRIREG system in T cells. This technology allows for the induction of transgene expression following the consumption of a diet deficient in an essential amino acid, by activating the GCN2-ATF4 signaling pathway. To utilize the NUTRIREG technology for therapeutic purposes in cell therapy with short-term EAA deprivation, we explored the general impact of 6-hour leucine deprivation on primary activated human T cells using RNA-seq technology. We identified 3,431 differentially expressed genes (adjusted p-value < 0.05) between T cells cultured in control media and those cultured in leucine-deprived media for 6 hours. Gene Set Enrichment Analysis revealed that "TNFα signaling via NFκB", "interferon-γ response", and "unfolded protein response" gene sets were positively enriched, while "mTORC1 signaling", "Myc targets", and "oxidative phosphorylation" gene sets were negatively enriched. T cells were cultured with or without a GCN2 inhibitor, which allowed us to assess the involvement of GCN2 kinase in differential gene expression during the 6-hour leucine deprivation. We found that 59% of the differentially expressed genes (DEGs) in our dataset were dependent on GCN2 kinase (n=2028), with 1,140 up-regulated and 888 down-regulated GCN2-dependent genes.
2025-01-20 | GSE279263 | GEO
Project description:Glutamine is a key nutrient for tumor cells that supports nucleotide and amino acid biosynthesis, replenishes the TCA cycle intermediates and contributes to redox metabolism. We identified oncogenic KRAS as a critical regulator of the response to glutamine deprivation in NSCLC. Full activation of the ATF4 stress response pathway is dependent on expression of NRF2 downstream of oncogenic KRAS in NSCLC. Through this mechanism, KRAS alters amino acid uptake and metabolism and sustains mTORC1 signaling during nutrient stress. Furthermore, we identified regulation of asparagine synthetase (ASNS) as a key effect of oncogenic KRAS signaling via ATF4 during glutamine deprivation, and a potential therapeutic target in KRAS mutant NSCLC.
2017-12-30 | GSE81643 | GEO
Project description:Glutamine is a key nutrient for tumor cells that supports nucleotide and amino acid biosynthesis, replenishes the TCA cycle intermediates and contributes to redox metabolism. We identified oncogenic KRAS as a critical regulator of the response to glutamine deprivation in NSCLC. Full activation of the ATF4 stress response pathway is dependent on expression of NRF2 downstream of oncogenic KRAS in NSCLC. Through this mechanism, KRAS alters amino acid uptake and metabolism and sustains mTORC1 signaling during nutrient stress. Furthermore, we identified regulation of asparagine synthetase (ASNS) as a key effect of oncogenic KRAS signaling via ATF4 during glutamine deprivation, and a potential therapeutic target in KRAS mutant NSCLC.
2017-12-30 | GSE81642 | GEO
Project description:Glutamine is a key nutrient for tumor cells that supports nucleotide and amino acid biosynthesis, replenishes the TCA cycle intermediates and contributes to redox metabolism. We identified oncogenic KRAS as a critical regulator of the response to glutamine deprivation in NSCLC. Full activation of the ATF4 stress response pathway is dependent on expression of NRF2 downstream of oncogenic KRAS in NSCLC. Through this mechanism, KRAS alters amino acid uptake and metabolism and sustains mTORC1 signaling during nutrient stress. Furthermore, we identified regulation of asparagine synthetase (ASNS) as a key effect of oncogenic KRAS signaling via ATF4 during glutamine deprivation, and a potential therapeutic target in KRAS mutant NSCLC.
2017-12-30 | GSE81641 | GEO
Project description:Lysosomes are central platforms for not only the degradation of macromolecules but also the integration of multiple signaling pathways. However, whether and how lysosomes mediate the mitochondrial stress response (MSR) remain largely unknown. Here, we demonstrate that lysosomal acidification via the vacuolar H+-ATPase (v-ATPase) is essential for the transcriptional activation of the mitochondrial unfolded protein response (UPRmt). Mitochondrial stress stimulates v-ATPase-mediated lysosomal activation of the mechanistic target of rapamycin complex 1 (mTORC1), which then directly phosphorylates the MSR transcription factor, activating transcription factor 4 (ATF4). Disruption of mTORC1-dependent ATF4 phosphorylation blocks the UPRmt, but not other similar stress responses, such as the UPRER. Finally, ATF4 phosphorylation downstream of the v-ATPase/mTORC1 signaling is indispensable for sustaining mitochondrial redox homeostasis and protecting cells from reactive oxygen species (ROS)-associated cell death upon mitochondrial stress. Thus, v-ATPase/mTORC1-mediated ATF4 phosphorylation via lysosomes links mitochondrial stress to UPRmt activation and mitochondrial function resilience.
2023-06-19 | GSE179510 | GEO
Project description:La-related protein 1 (LARP1) has been identified as a key translational inhibitor of terminal oligopyrimidine tract (TOP) mRNAs downstream of the nutrient sensing protein kinase complex, mTORC1. LARP1 exerts this inhibitory effect on TOP mRNA translation by binding to the mRNA cap and the adjacent 5’TOP motif, resulting in the displacement of the eIF4E complex from TOP mRNAs. In the present study, we identify a second nutrient sensing kinase GCN2 that converges on LARP1 to control TOP mRNA translation. GCN2 inhibits TOP mRNA translation via ATF4-dependent transcriptional induction of LARP1 mRNAs and GCN1-mediated recruitment of LARP1 to stalled ribosomes. We performed ATF4 ChIP-seq experiments in both WT and GCN2 KO MEFs with or without leucine deprivation.
2022-08-31 | GSE166590 | GEO
Project description:Lysosomes mediate the mitochondrial UPR via mTORC1-dependent ATF4 phosphorylation
| PRJNA744091 | ENA
Project description:In response to a variety of upstream growth and oncogenic signals, the mechanistic target of rapamycin complex 1 (mTORC1) promotes anabolic metabolism, in part, through activation of downstream transcription factors. The transcription factor activating transcription factor 4 (ATF4) has been previously shown to function downstream of mTORC1 signaling to promote de novo purine synthesis and this activation of ATF4 can occur independently of the canonical activation of ATF4 through the integrated stress response (ISR). Here, we show that ATF4 activation through mTORC1 signaling drives a specific transcriptional program through ATF4 which is comprised of only a subset of genes involved in the broader cellular stress response. We find genes involved in amino acid uptake, biosynthesis, and charging by tRNA synthetases display transcriptional changes downstream of both mTORC1 and ATF4. We discovered that ATF4 activation contributes to the mTORC1-stimulated increase in protein synthesis, highlighting the importance of these transcriptional changes. Additionally, we observe regulation of the cystine transporter SLC7A11 by ATF4. We show that SLC7A11 is important for cell survival and is one mechanism by which cells with active mTORC1 signaling produce glutathione. Thus, ATF4 downstream of mTORC1 signaling regulates protein and glutathione synthesis.
2020-09-28 | GSE158605 | 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