Gcn2 eIF2a kinase mediates combinatorial translational regulation through nucleotide motifs and uORFs in the mRNA 5’ leader regions
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PROVIDER: PRJNA599945 | ENA |
REPOSITORIES: ENA
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Project description:Cellular signaling controls translation through cis regulatory elements found in mRNAs. Gcn2 is the master regulator of translation during nutrient limitation in normal and cancer cells. Activated Gcn2 phosphorylates eIF2a, thereby repressing general translation while activating translation of specific mRNAs with upstream ORFs (uORFs) in its leader regions. Here we performed genome-wide measurement of mRNA translation during histidine starvation in fission yeast Schizosaccharomyces pombe. Polysomal microarray hybridization experiments identified a group of 1779 genes whose translation is up-regulated in Gcn2-dependent manner. We find that translation is reprogrammed to enhance organellar synthesis and transcription and repress ribosome synthesis. The 1779 genes included gcn5 and hri2 shown to promote growth under histidine starvation. They encode histone acetyl transferase and heme-binding eIF2a kinase activated by oxidative stress, and their 5’-leader contains 3 or 4 uORFs, respectively. Our reporter studies show that uORFs in gcn5 and hri2 operate similarly to those found in S. cerevisiae GCN4, the founding case for uORF-dependent regulation. Moreover, motif analysis identified 5’-UGA(C/G)GG-3’ as a motif promoting translation during starvation. Using hrd1 5’UTR with such a motif, we demonstrated its requirement in Gcn2-dependent translational control. To our knowledge, this is the first nucleotide motif found to be responsible for translational control by Gcn2. We propose that Gcn2 mediates translational control of more specific mRNAs than previously anticipated
2020-09-23 | GSE143299 | GEO
Project description:To study the mitochondrial stress response HRI-eIF2a-ATF4 signaling pathway in mitochondrial cardiomyopathy , we generated Ptpmt1 cardiomyocytes-specific Knockout mcie, Eif2a mutant mcie, Gcn2 Knockout mcie, and Hri Knockout mcie
2022-04-21 | GSE201042 | GEO
Project description:General translational repression is predicted as a key process to reduce energy consumption under hypoxia. We have previously showed that mRNA loading onto polysome is reduced in Arabidopsis under submergence. Here, we showed that plant stress activated GCN2 (general control nonderepressible 2) can phosphorylate eIF2a (Eukaryotic Initiation Factor 2a) in Arabidopsis under submergence, and this process is reversible after desubmergence. Compared to the wild-type, the reduction in polysome loading during submergence was less severe in the gcn2 mutant. Transgenic lines overexpressing GCN2 had more ATP and conferred better tolerance under submergence, suggesting that GCN2 might modulate the dynamics of translation to adjust the energy homeostasis under hypoxia. Interestingly, GCN2-eIF2a signaling was activated by ethylene under submergence. However, GCN2 activity was not affected in ein2-5 and eil1ein3 under submergence, suggesting that GCN2 activity was regulated by noncanonical ethylene signaling. In addition, the polysome loading was retained in both ein2-5 and etr1-1 under submergence, implying that ethylene modulated the dynamic translation under submergence via EIN2 and GCN2. Notably, our NGS analysis also demonstrated that EIN2 and GCN2 regulated the translation of 23 core hypoxia genes as well as 53% translational repressed genes under submergence. On the other hand, EIN2 and GCN2 also affected the expression of genes involved in hypoxic response, ethylene response, biotic stress and negative regulation of cytokinin signaling. Taken together, these demonstrated that entrapped ethylene triggers GCN2 and EIN2 to ensure the translation of stress required proteins under submergence and also provide a step stone for future investigation how eukaryotic cells modulate the translation to response for the changeable environments.
2022-06-08 | GSE149414 | GEO
Project description:The integrated stress response (ISR) is a central signalling network that enables eukaryotic cells to respond to a variety of different environmental stresses. Such stresses cause ribosome collisions that lead to activation of the kinase Gcn2, resulting in the phosphorylation and inactivation of eukaryotic initiation factor 2 and thereby promoting selective translation of mRNAs to restore homeostasis. Despite the importance of the ISR and intensive study over the past decades, structural insight into how Gcn2 interacts with ribosomal particles has been lacking. Using ex vivo affinity purification approaches, we have obtained a native structure of a Gcn2 dimer in complex with the ribosomal 60S subunit. The Gcn2 dimer is formed by dimerization of the histidine tRNA synthetase-like domains, which establish extensive interactions with the stalk-base and sarcin-ricin loop of the 60S subunit. The C-terminal domain of Gcn2 is also dimerized and occupies the A- and P-site tRNA binding sites at the peptidyl-transferase center of the 60S subunit. Complementary functional studies indicate that binding of Gcn2 to the 60S subunit does not require the co-activators Gcn1 or Gcn20, nor does it lead to phosphorylation of eIF2a. Rather, upon stress, we observe a shift of Gcn2 from the 60S subunit into the colliding ribosome fraction, suggesting that the Gcn2-60S complex represents an inactive stand-by state to enable a rapid redistribution to collided ribosomes, and thereby facilitating a quick and efficient response to stress.
2024-09-16 | PXD055898 | Pride
Project description:The RNA-binding protein eIF2A has been implicated in a variety of cellular processes including tumorigenesis. This role has been attributed to its function as alternative translation initiation factor. However, the mechanisms by which eIF2A regulates translation and its contribution to oncogenic transformation are unclear. Here, we shed light on these aspects using a melanoma cell model consisting of the non-tumoral melanocytic cell line MelST and its metastatic counterpart obtained by RasV12 overexpression (MelSTR). Depletion of eIF2A from MelST and MelSTR cells revealed acquired dependencies upon Ras transformation for migration. Surprisingly, analysis of the transcriptome (RNA-Seq) and translatome (ribosome profiling) upon eIF2A depletion showed minor to no changes in translation. RIP-Seq and RT-qPCR furthermore indicate that eIF2A binds mRNA targets in a translation-independent manner. Interestingly, protein interactome analyses point towards a function of eIF2A in cytoskeletal remodeling and indeed we can show that eIF2A localizes to the centrosome and affects its composition and orientation, linking eIF2A with migration. In addition, eIF2A promotes migration in a manner that depends on its RNA-binding activity. Together, these results indicate that eIF2A does not function as a translation factor in melanoma cells, but through a novel function which is based on its RNA-binding activity and its connections to the centrosome.
2025-06-27 | GSE279657 | GEO
Project description:The RNA-binding protein eIF2A has been implicated in a variety of cellular processes including tumorigenesis. This role has been attributed to its function as alternative translation initiation factor. However, the mechanisms by which eIF2A regulates translation and its contribution to oncogenic transformation are unclear. Here, we shed light on these aspects using a melanoma cell model consisting of the non-tumoral melanocytic cell line MelST and its metastatic counterpart obtained by RasV12 overexpression (MelSTR). Depletion of eIF2A from MelST and MelSTR cells revealed acquired dependencies upon Ras transformation for migration. Surprisingly, analysis of the transcriptome (RNA-Seq) and translatome (ribosome profiling) upon eIF2A depletion showed minor to no changes in translation. RIP-Seq and RT-qPCR furthermore indicate that eIF2A binds mRNA targets in a translation-independent manner. Interestingly, protein interactome analyses point towards a function of eIF2A in cytoskeletal remodeling and indeed we can show that eIF2A localizes to the centrosome and affects its composition and orientation, linking eIF2A with migration. In addition, eIF2A promotes migration in a manner that depends on its RNA-binding activity. Together, these results indicate that eIF2A does not function as a translation factor in melanoma cells, but through a novel function which is based on its RNA-binding activity and its connections to the centrosome.
2025-06-27 | GSE279472 | GEO
Project description:The RNA-binding protein eIF2A has been implicated in a variety of cellular processes including tumorigenesis. This role has been attributed to its function as alternative translation initiation factor. However, the mechanisms by which eIF2A regulates translation and its contribution to oncogenic transformation are unclear. Here, we shed light on these aspects using a melanoma cell model consisting of the non-tumoral melanocytic cell line MelST and its metastatic counterpart obtained by RasV12 overexpression (MelSTR). Depletion of eIF2A from MelST and MelSTR cells revealed acquired dependencies upon Ras transformation for migration. Surprisingly, analysis of the transcriptome (RNA-Seq) and translatome (ribosome profiling) upon eIF2A depletion showed minor to no changes in translation. RIP-Seq and RT-qPCR furthermore indicate that eIF2A binds mRNA targets in a translation-independent manner. Interestingly, protein interactome analyses point towards a function of eIF2A in cytoskeletal remodeling and indeed we can show that eIF2A localizes to the centrosome and affects its composition and orientation, linking eIF2A with migration. In addition, eIF2A promotes migration in a manner that depends on its RNA-binding activity. Together, these results indicate that eIF2A does not function as a translation factor in melanoma cells, but through a novel function which is based on its RNA-binding activity and its connections to the centrosome.
2025-06-27 | GSE279471 | 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.
2009-11-23 | E-GEOD-11496 | biostudies-arrayexpress
Project description:The RNA-binding protein eIF2A has been implicated in a variety of cellular processes including tumorigenesis. This role has been attributed to its function as alternative translation initiation factor. However, the mechanisms by which eIF2A regulates translation and its contribution to oncogenic transformation are unclear. Here, we shed light on these aspects using a melanoma cell model consisting of the non-tumoral melanocytic cell line MelST and its metastatic counterpart obtained by RasV12 overexpression (MelSTR). Depletion of eIF2A from MelST and MelSTR cells revealed acquired dependencies upon Ras transformation for migration. Surprisingly, analysis of the transcriptome (RNA-Seq) and translatome (ribosome profiling) upon eIF2A depletion showed minor to no changes in translation. RIP-Seq and RT-qPCR furthermore indicate that eIF2A binds mRNA targets in a translation-independent manner. Interestingly, protein interactome analyses point towards a function of eIF2A in cytoskeletal remodeling and indeed we can show that eIF2A localizes to the centrosome and affects its composition and orientation, linking eIF2A with migration. In addition, eIF2A promotes migration in a manner that depends on its RNA-binding activity. Together, these results indicate that eIF2A does not function as a translation factor in melanoma cells, but through a novel function which is based on its RNA-binding activity and its connections to the centrosome.
2025-08-05 | PXD055625 | Pride
Project description:Gene expression profile at Ptpmt1 cardiomyocytes-specific Knockout mcie, Eif2a mutant mice, Gcn2 Knockout mice, and Hri Knockout mice
| PRJNA828131 | ENA