ATF4 couples MYC-dependent translational activity to bioenergetic demands during tumor progression
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PROVIDER: PRJNA481516 | ENA |
REPOSITORIES: ENA
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Project description:Dysregulation of the proto-oncogene c-Myc (MYC henceforward) drives malignant progression, but also induces robust anabolic and proliferative programs leading to intrinsic stress. The mechanisms enabling adaptation to MYC-induced stress are not fully understood. We have uncovered an essential role for the transcription factor ATF4 in cell survival following MYC activation. MYC- upregulates ATF4 by activating GCN2 kinase through uncharged tRNAs. Subsequently, ATF4 co-occupies promoter regions of over 30 MYC target genes, including those regulating amino acid biosynthesis/transport and protein synthesis. ATF4 is essential for MYC-induced upregulation of the negative translational regulator and mTOR target 4E-BP1 and genetic or pharmacological inhibition of mTOR signaling rescues ATF4 deficient cells from MYC-induced stress. Acute deletion of ATF4 significantly delays MYC-driven tumor progression and increases survival in mouse models. Our results establish ATF4 as a cellular rheostat of MYC-activity, ensuring enhanced translation rates are compatible with survival and tumor progression.
2018-07-18 | GSE117240 | GEO
Project description: Not available
| S-EPMC6608727 | biostudies-literature
Project description:Disruptions of protein homeostasis in the endoplasmic reticulum (ER) elicit activation of the unfolded protein response (UPR), a translation- and transcription-coupled proteostatic stress response pathway. The primary translational control arm of the UPR is initiated by the PERK-dependent phosphorylation of eIF2α, leading to a large-scale reprogramming of translation and subsequent activation of an ATF4-mediated transcriptional program. It has remained challenging, however, to accurately evaluate the contribution of each component of the eIF2α/ATF4 pathway to the remodelling of transcription and translation. Here, we have used mouse embryonic fibroblasts containing either a knock-in of the non-phosphorylatable eIF2α S51A mutant or knock-out for ATF4 by ribosome profiling and mRNA-seq to define the specific contributions of eIF2α phosphoryation and ATF4 in controlling the translational and transcriptional components of the UPR. These studies show that the transcriptional and translational targets of each P-eIF2α, ATF4, and the other UPR gene expression programs overlapped extensively, leading to a core set of UPR genes whose robust expression in response to ER stress is driven by multiple mechanisms. The identification of other, more factor-specific targets illustrated the potential for functional specialization of the UPR. As the UPR progressed temporally, cells employed distinct combinations of transcriptional and translational mechanisms, initiated by different factors, to adapt to ongoing stress. These effects were accompanied by a buffering effect where changes in mRNA levels were coupled to opposing changes in ribosome loading, a property which makes cooperation between transcription and translation essential to confer robust protein expression. Translational analysis by ribosome profiling and mRNA-seq of PERK pathways mutants during the UPR. Mouse embryonic fibroblasts (MEFs) lacking components of the PERK pathway (eIF2a phosphorylation and ATF4) were subjected to ER stress and analyzed by ribosome profiling.
2016-07-03 | E-GEOD-68265 | biostudies-arrayexpress
Project description:Cancer cells frequently hijack adaptive stress response signals/pathways to protect themselves from metabolic or genetic vulnerabilities, pointing to candidate therapeutic targets. Among these SIRT3 was recently identified as a non-oncogene addiction mechanism in DLBCL through its role in glutamine metabolism. Here, we investigated downstream signaling pathways linked to SIRT3 function in lymphoma. We performed RNA-seq in DLBCL cells after SIRT3 knockdown and observed that ATF4 target genes were significantly downregulated in SIRT3 deficient cells. ATF4, a master regulator of cellular stress, was required to maintain proliferation and survival of DLBCL cells and its target genes were overexpressed in DLBCL patients as compared to normal germinal center B cells. Translation of ATF4 mRNA was inhibited in SIRT3 knockdown cells and expression of exogenous ATF4 partially rescued cell proliferation and viability inhibited by SIRT3 deficiency. Accordingly, ATF4 protein was expressed at relatively lower levels SIRT3 deficient murine lymphomas, whereas its higher expression was associated with more severe disease. We characterized mechanisms through which SIRT3 maintains ATF4 expression, downstream of its effects on glutamine entry into the TCA cycle and suppression of autophagy. Specifically, loss of SIRT3 disrupted amino acid metabolism in DLBCL cells, with subsequent impairment of ATF4 response to metabolic stressors such as glutamine depletion. Collectively, the data suggest a key SIRT3-ATF4 axis maintains survival of DLBCL cells enabling them to optimize amino acid metabolism and cope with metabolic vulnerabilities possibly associated with their high proliferative rate.
2022-09-20 | GSE158833 | GEO
Project description:For additional details see Ebert et al, Identification and Small Molecule Inhibition of an ATF4-dependent Pathway to Age-related Skeletal Muscle Weakness and Atrophy. Quadriceps femoris muscles were harvested from 22-month-old muscle-specfic ATF4 knockout (ATF4 mKO) mice and littermate controls. mRNA levels in ATF4 mKO muscles were normalized to levels in littermate control muscles.
2015-09-03 | E-GEOD-72658 | biostudies-arrayexpress
Project description:To determine gene expression changes induced by ATF4 overexpression, RNA was isolated from BEAS2B cells after overexpression of ATF4 or negative control. mRNA expression was profiled using Affymetrix Human Gene 1.0 ST Arrays. RNA isolated from BEAS2B cells after overexpression of ATF4 or empty vector was processed and hybridized to Affymetrix Human Gene 1.0 ST Arrays. Experiments were performed in triplicate. Data from the 6 microarrays were used for RMA normalization. RMA normalization was performed in the R statsitical environment using the affy package. A t-test was used to determine the association of gene expression with ATF4 overexpression.
2013-05-01 | E-GEOD-45949 | biostudies-arrayexpress
Project description:Activating Transcription Factor 4 (ATF4) is a transcription factor induced by the integrated stress response (ISR). This experiment is a genome-wide profiling of ATF4-dependent RNA expression in human HAP-1 cells. HAP-1 is a near-haploid human cell line that was derived from KBM-7 cells isolated from a patient with Chronic Myelogenous Leukemia. We analyzed WT and ATF4 KO cells. We induced ATF4 expression by mimicking amino acid starvation with the drug histidinol. RNA expression profiles were generated for WT and ATF4 KO HAP1 cells. ATF4 genes were mutated using Cas9 genome editing technology. Amino acid starvation was mimicked by treating WT and ATF4 KO cells with 2 mM histidinol for 24 hours, which increases ATF4 expression.
2015-08-28 | E-GEOD-69308 | biostudies-arrayexpress
Project description:Disruptions of protein homeostasis in the endoplasmic reticulum (ER) elicit activation of the unfolded protein response (UPR), a translation- and transcription-coupled proteostatic stress response pathway. The primary translational control arm of the UPR is initiated by the PERK-dependent phosphorylation of eIF2α, leading to a large-scale reprogramming of translation and subsequent activation of an ATF4-mediated transcriptional program. It has remained challenging, however, to accurately evaluate the contribution of each component of the eIF2α/ATF4 pathway to the remodelling of transcription and translation. Here, we have used mouse embryonic fibroblasts containing either a knock-in of the non-phosphorylatable eIF2α S51A mutant or knock-out for ATF4 by ribosome profiling and mRNA-seq to define the specific contributions of eIF2α phosphoryation and ATF4 in controlling the translational and transcriptional components of the UPR. These studies show that the transcriptional and translational targets of each P-eIF2α, ATF4, and the other UPR gene expression programs overlapped extensively, leading to a core set of UPR genes whose robust expression in response to ER stress is driven by multiple mechanisms. The identification of other, more factor-specific targets illustrated the potential for functional specialization of the UPR. As the UPR progressed temporally, cells employed distinct combinations of transcriptional and translational mechanisms, initiated by different factors, to adapt to ongoing stress. These effects were accompanied by a buffering effect where changes in mRNA levels were coupled to opposing changes in ribosome loading, a property which makes cooperation between transcription and translation essential to confer robust protein expression.
2016-01-01 | GSE68265 | GEO
Project description:Translation initiation in higher eukaryotes is orchestrated by the tight regulation of the cap binding and the 43S pre-initiation complexes (PIC). The PIC component eukaryotic initiation factor 1A (EIF1A), encoded on human chromosomes X and Y by EIF1AX and EIF1AY, respectively, is essential for recruitment of the ternary complex and for assembling the 43S PIC, which after recruitment onto capped mRNAs scans their 5’UTR and localizes the AUG to initiate translation. Recurrent EIF1AX mutations are found in several cancers, including ~1% of papillary thyroid cancers in a mutually exclusive manner with other drivers (BRAF, RAS, and oncogenic fusions). They are enriched in advanced thyroid cancers (11%) where they display a striking co-occurrence with RAS, which we show cooperate to induce tumorigenesis in mouse models and in isogenic cell lines. The C-terminal tail EIF1AX-A113splice mutation is the most prevalent in advanced thyroid cancer, and private to this disease. We found that EIF1AX-A113spl variants stabilize the PIC and induces ATF4 expression, a sensor of cellular stress, which is co-opted to suppress EIF-2α phosphorylation, thus enabling a general increase in protein synthetic rate. RAS stabilizes c-MYC, an effect augmented by EIF1AX-A113spl. ATF4 and c-MYC induce expression of aminoacid transporters, and enhance sensitivity of mTOR to aminoacid supply. These mutually reinforcing events generate therapeutic vulnerabilities to MEK, BRD4 and mTOR kinase inhibitors. The RNA-Seq and Ribosome Profiling samples provided here were used to support the claim of increased translational efficiency of ATF4.
2019-01-28 | GSE113695 | GEO
Project description:Activating Transcription Factor 4 (ATF4) is a transcription factor induced by the integrated stress response (ISR). This experiment is a genome-wide occupancy profiling of ATF4 in human HAP1 cells. HAP1 is a near-haploid human cell line that was derived from KBM-7 cells isolated from a patient with Chronic Myelogenous Leukemia. We induced ATF4 expression by mimicking amino acid starvation with the drug histidinol. We identified peaks of ATF4 binding using three independent antibodies. Examination of ATF4 binding in HAP1 cells treated with 2 mM histidinol for 24 hours.
2015-08-28 | E-GEOD-69304 | biostudies-arrayexpress