The mTORC1-mediated activation of ATF4 promotes protein and glutathione synthesis (Tunicamycin)
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ABSTRACT:
PROVIDER: PRJNA665968 | ENA |
REPOSITORIES: ENA
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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:The mammalian target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth that is commonly deregulated in human diseases. Here we find that mTORC1 controls a transcriptional program encoding amino acid transporters and metabolic enzymes through a mechanism also used to regulate protein synthesis. Bioinformatic analysis of mTORC1-responsive mRNAs identified a promoter element recognized by activating transcription factor 4 (ATF4), a key effector of the integrated stress response. ATF4 translation is normally induced by phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α) through a mechanism that requires upstream open reading frames (uORFs) in the ATF4 5' UTR. mTORC1 also controls ATF4 translation through uORFs, but independent of changes in eIF2α phosphorylation. mTORC1 instead employs the 4E-binding protein (4E-BP) family of translation repressors. These results link mTORC1-regulated demand for protein synthesis with an ATF4-regulated transcriptional program that controls the supply of amino acids to the translation machinery.
2017-04-15 | GSE97384 | GEO
Project description:To further development of our miRNA expression approach to ER stress, we have employed miRNA microarray expression profiling as a discovery platform to identify ER stress-responsible ones. Mouse embryonic fibroblasts (MEFs) deficient in a ER stress mediator ATF4 were treated with tunicamycin for 12 or 24 hrs. miRNAs responsible for tunicamycin-treatment for 12hrs in ATF4-dependent manner were extracted. Among them, expression of three miRNAs (miR-193b, miR-423-5p, miR-199a-3p) was quantified in the RNA samples from the same as the microarray by real-time PCR. Mouse embryonic fibroblasts (MEFs) deficient in a ER stress mediator ATF4 were treated with 2ug/mL tunicamycin for 12 or 24 hrs. Two independent experiments were performed at each time (untreated, 12 or 24 hrs). miRNAs responsible for tunicamycin-treatment for 12hrs in ATF4-dependent manner were extracted.
2015-01-18 | E-GEOD-35175 | biostudies-arrayexpress
Project description:Glutathione peroxidase 4 (GPX4) utilizes glutathione (GSH) to detoxify lipid peroxidation and
plays an essential role in inhibiting ferroptosis. As a selenoprotein, GPX4 protein synthesis is
highly inefficient and energetically costly. How cells coordinate GPX4 synthesis with nutrient
availability remains unclear. In this study, integrated proteomic and functional analyses reveal
that SLC7A11-mediated cystine uptake promotes not only GSH synthesis but also GPX4 protein synthesis. Mechanistically, cyst(e)ine activates mechanistic/mammalian target of rapamycin complex 1 (mTORC1) and promotes GPX4 protein synthesis at least partly through the mTORC1-4E-BP signaling axis. Pharmacologic inhibition of mTORC1 decreases GPX4 protein levels, sensitizes cancer cells to ferroptosis, and synergizes with ferroptosis inducers (FINs) to suppress patient-derived xenograft tumor growth in vivo. Together, our results reveal a hitherto unrecognized regulatory mechanism to coordinate GPX4 protein synthesis with cyst(e)ine availability and suggest to use the combination of mTORC1 inhibitors and FINs in cancer treatment.
2020-08-25 | MSV000086009 | MassIVE
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:To further development of our miRNA expression approach to ER stress, we have employed miRNA microarray expression profiling as a discovery platform to identify ER stress-responsible ones. Mouse embryonic fibroblasts (MEFs) deficient in a ER stress mediator ATF4 were treated with tunicamycin for 12 or 24 hrs. miRNAs responsible for tunicamycin-treatment for 12hrs in ATF4-dependent manner were extracted. Among them, expression of three miRNAs (miR-193b, miR-423-5p, miR-199a-3p) was quantified in the RNA samples from the same as the microarray by real-time PCR.
2015-01-18 | GSE35175 | GEO
Project description:We examined ATF4 genomic occupancy resulting from treatment of HCT116 colon carcinoma human cell lines with DMSO, etoposide, histidinol, or, tunicamycin, using Cut&Run.
2022-08-20 | GSE211264 | GEO
Project description:We report the direct target genes of ATF4 and CHOP in response to endoplasim reticulum stress through next generation sequencing. By obtaining genowide sequence from chromatin immunoprecipitated DNA with anti-CHOP and anit-ATF4, we identified direct binding sites of ATF4 and CHOP in promoter regions of their target genes in mouse embrynic fibroblasts (MEFs) in response to ER stress. In addition, we obtained list of genes which are differentially regulated in Atf4 or Chop-deficient MEFs compared to the wild-type MEFs in response to ER stress. We found that genes related with unfolded protein response and protein synthesis were directly regulated by ATF4 and CHOP. Through this observation, we conclude that main role of ATF4 and CHOP as transcription factors is to enhance mRNA translation in respone to ER stress. This sutdy provide new insight of genetic network of ATF4 and CHOP in response to ER stress. For ChIP-seq, Chop+/+ and Chop-/- MEFs were treated with Tunicamycin, N-glycosylation inhibitor, to induce ER stress for 8hr. Atf4+/+ and Atf4-/- MEFs were also treated same condition for ChIP-Seq. For mRNA-seq, wild-type, Atf4-/-, and Chop-/- MEFs were treated with tunicamycin for 8hr for experiments.
2013-04-11 | E-GEOD-35681 | biostudies-arrayexpress
Project description:Oxidative stress is pathogenic in neurological diseases including stroke. The identity of oxidative stress-inducible transcription factors and their role(s) in propagating the death cascade are poorly understood. Microarray analysis of neurons undergoing oxidative stress showed significant induction of prodeath genes. These genes have been shown to be regulated by the bZip transcription factor, ATF4. ATF4 protein localized to the promoter of a putative death gene in neurons in vitro and in vivo. Germline deletion of ATF4 in neurons resulted in a reduction in oxidative stress-induced gene expression and resistance to oxidative death. ATF4 knockout mice experienced significantly smaller infarcts and improved behavioral recovery as compared to wild-type mice subjected to the same reductions in blood flow in a rodent model of stroke. ATF4 modulates an early, upstream event in the death pathway, as resistance to oxidative death by ATF4 deletion was associated with decreased consumption of the antioxidant glutathione. Restoration of ATF4 protein in knockout neurons was sufficient to restore sensitivity to oxidative death and to reaccelerate loss of glutathione. Together, these findings establish ATF4 as a redox-regulated, pro-death transcriptional activator in the nervous system that propagates death responses to oxidative stress in vitro and to stroke in vivo. Keywords: ATF4, oxidative stress, gene expression, neuroprotection, stroke WT and ATF4 KO embryonic neurons were studied. Untreated neurons (no=8 per genotype) and neurons challenged with oxidative stress with the glutamate homolog homocysteate (HCA, no=4 per genotype) were studied, for a total of 24 samples.
2010-06-25 | E-GEOD-10470 | biostudies-arrayexpress
Project description: Not available
| S-EPMC7997658 | biostudies-literature