Maintenance of p-eIF2 alpha levels by the eIF2B complex is vital for colorectal cancer
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1047524 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR27012908.fastq.gz | Fastqsanger.gz | |||
| SRR27012909.fastq.gz | Fastqsanger.gz | |||
| SRR27012910.fastq.gz | Fastqsanger.gz | |||
| SRR27012911.fastq.gz | Fastqsanger.gz | |||
| SRR27012912.fastq.gz | Fastqsanger.gz |
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Project description:Protein synthesis is an essential cellular process highly deregulated in multiple tumour types, where control of several translation factors is hijacked to benefit oncogenic growth. Here we show that colorectal cancer (CRC) is characterized specifically by elevated levels of phosphorylated eukaryotic initiation factor 2 alpha (p-eIF2alpha). In contrast to its canonical association with reduced translation rates, we reveal that CRC with high p-eIF2alpha has increased protein synthesis rates. Thus, we hypothesize that eIF2B, the sensor of p-eIF2 alpha, plays a central role in cells’ inability to relay this inhibitory signal. Using a combination of in cellulo biochemistry, phenotypic assays, and analysis of translation upon modulation of eIF2B subunits alpha and delta, the two eIF2B subunits responsible for sensing p-eIF2 alpha, we demonstrate that CRC cells require an intact eIF2B complex to sense p-eIF2 alpha. Crucially, we show that the alpha subunit of eIF2B is necessary to translate the oncogenic programs driven by APC loss, highlighting its central role in oncogenic transformation. To conclude, we demonstrate that whilst normal cells do not depend on eIF2B alpha, CRC cells require this eIF2B subunit for correct sensing of p-eIF2 alpha and regulation of their proteostasis, thus validating eIF2B alpha as a target for therapeutic intervention in CRC.
2025-01-09 | GSE249128 | GEO
Project description:Various stressors such as viral infection lead to the suppression of cap-dependent translation and the activation of the integrated stress response (ISR), since the stress-induced phosphorylated eukaryotic translation initiation factor 2 [eIF2(αP)] tightly binds to eIF2B to prevent it from exchanging guanine nucleotide molecules on its substrate, unphosphorylated eIF2. Sandfly fever Sicilian virus (SFSV) evades this cap-dependent translation suppression through the interaction between its nonstructural protein NSs and host eIF2B. However, its precise mechanism has remained unclear. Here, our cryo-electron microscopy (cryo-EM) analysis revealed that SFSV NSs binds to the α-subunit of eIF2B in a competitive manner with eIF2(αP). Together with SFSV NSs, eIF2B retains nucleotide exchange activity even in the presence of eIF2(αP), in line with the cryo-EM structures of the eIF2B•SFSV NSs•unphosphorylated eIF2 complex. A genome-wide ribosome profiling analysis clarified that SFSV NSs expressed in cultured human cells attenuates the ISR triggered by thapsigargin, an endoplasmic reticulum stress inducer. Furthermore, SFSV NSs introduced in rat hippocampal neurons and human induced-pluripotent stem (iPS) cell-derived motor neurons exhibited neuroprotective effects against the ISR-inducing stress. Since ISR inhibition is beneficial in various neurological disease models, SFSV NSs is promising as a therapeutic ISR inhibitor.
2021-11-11 | GSE174764 | GEO
Project description:Protein synthesis is an essential process, deregulated in multiple tumor types showing differential dependence on translation factors compared to untransformed tissue. We show that colorectal cancer (CRC) with loss-of-function mutation in the APC tumor suppressor depends on an oncogenic translation program regulated by the ability to sense phosphorylated eIF2a (p-eIF2a). Despite increased protein synthesis rates following APC loss, eIF2a phosphorylation, typically associated with translation inhibition, is enhanced in CRC. Elevated p-eIF2a, and its proper sensing by the decameric eIF2B complex, are essential to balance translation. Knockdown or mutation of eIF2Ba and eIF2Bd, two eIF2B subunits responsible for sensing p-eIF2a, impairs CRC viability, demonstrating that the eIF2B/p-eIF2a nexus is vital for CRC. Specifically, the decameric eIF2B linked by two eIF2Ba subunits is critical for translating growth-promoting mRNAs which are induced upon APC loss. Depletion of eIF2Ba in APC-deficient murine and patient-derived organoids establishes a therapeutic window, validating eIF2Ba as a target for clinical intervention. In conclusion, we demonstrate how expression of the oncogenic signature in CRC is crucially controlled at the translational level.
| S-SCDT-10_1038-S44318-025-00381-9 | biostudies-other
Project description:Purpose: The integrated stress response (ISR) attenuates the rate of protein synthesis while inducing expression of stress proteins in cells. Various insults activate kinases that phosphorylate the GTPase eIF2 leading to inhibition of its exchange factor eIF2B. Vanishing White Matter (VWM) is a neurological disease caused by eIF2B mutations that, like phosphorylated eIF2, reduce its activity. We performed RNA-seq analysis of cerebellum collected from mice harboring a homozygous point mutation in eIF2B5 (HO R191H), a mutation that causes a severe form of VWM in humans and compared gene expression to wildtype age-matched littermates to identify transcriptomic differences at early, mid and late time points during disease progression. We also performed RNA-seq on cerebellum collected from animals treated with the eIF2B activator 2BAct for 1 month to determine to what extent small molecule treatment could normalize the VWM transcriptome. Methods: Samples were collected at 2, 5, and 7 months of age. In addition, HO R191H and WT mice treated with and without with the eIF2B activator 2BAct for 1 month were profiled. RNA-seq libraries were prepared using purified RNA isolated from frozen tissue using the RNeasy Mini kit. RNA quality and concentration were assayed using a Fragment Analyzer instrument. RNA-seq libraries were prepared using the TruSeq Stranded Total RNA kit paired with the Ribo-Zero rRNA removal kit. Libraries were sequenced on an Illumina HiSeq 4000 instrument. For the experiment comparing different ages, N = 3 males/genotype/time point. For the 4-week 2BAct treatment experiment, N = 3 females/condition. Conclusions: HO R191H mutant brains show an elevated gene expression signature of the Integrated Stress Reponse in mice as early as 2 months, preceding the appearance of overt pathology in these animals. The expression of the ISR-related genes does not significantly increases at 5 months and 7 months of age. One month of treatment with 2BAct completely prevented the expression of ISR-related in genes in 2 month old animals.
2019-03-11 | GSE128092 | GEO
Project description:In times of cellular stress, such as during virus infections, the integrated stress response (ISR) blocks translation initiation through phosphorylation of the essential translation initiation factor eIF2. Phosphorylated eIF2 (p-eIF2) sequesters the eIF2-specific guanidine exchange factor (GEF) eIF2B, thereby preventing eIF2 recycling. Here we describe the first example of a viral ISR antagonist that inhibits the ISR at its most central step: the interplay between p-eIF2 and eIF2B. Using AP-MS, we determine that BW10 binds eIF2B. There, it selectively displaces eIF2B’s inhibitor p-eIF2 without affecting the association of its substrate eIF2. By this mechanism, BW10 renders cellular translation immune to regulation by eIF2 phosphorylation. Thus, under stress conditions BW10 creates the unprecedented situation of high levels of p-eIF2 coinciding with unimpaired translation.
2020-07-24 | PXD011879 | Pride
Project description:Genome-wide mRNA expression in brains of wild-type and eIF2B-R132H/R132H mutant mice (Geva et al., BRAIN 133 (8), 2010) profiled at postnatal (P) days 1, 18 and 21 to reflect the early proliferative stage prior to white matter establishment (P1) and the peak of oligodendrocye differentiation and myelin synthesis (P18 and P21). 3 biological replicates (whole brain without the cerebellum) from each wild-type and eIF2B-R132H/R132H mutant mice at 3 postnatal (P) days 1, 18 and 21 were used for RNA extraction and hybridization on Affymetrix microarrays.
2011-11-14 | E-GEOD-32201 | biostudies-arrayexpress
Project description:eIF2B is a master regulator of translation initiation and mediator of the integrated stress response (ISR). Partial-loss-of function mutations are associated with eIF2B-leukodystrophy termed Vanishing White Matter Disease (VWMD), a recessive neurodegenerative disorder. Astrocytes, the brain homeostasis keepers, are central to VWMD owing to their hyper-sensitivity to eIF2B activity, as manifested by their phenotypic deficits due to the mutation. Here we used astrocytes isolated from the brains of WT and eIF2B5R132H/R132H mice to assess their transcriptome and translatome responses upon cytokine-mediated activation, an mTOR-driven process critical for brain homeostasis. We found that: (i) a mild eIF2B mutation has the power to disrupt translation regulation programs involving ~30% of the expressed genes; (ii) a common compensatory strategy to overcome the translation regulation failure is manipulation of mRNA abundance; and (iii) dysregulation of functionally related genes can be used to reliably predict deficits of corresponding cellular functions. Specifically, the study illuminates the molecular anomalies responsible for the impaired ribogenesis and mitochondrial respiration of eIF2B-mutant astrocytes. Moreover, it reliably predicts, for the first time, impaired cholesterol biosynthesis in eIF2B-mutant astrocytes. This work demonstrates the strength of combined transcriptome/translatome approach to decipher links between mild expression anomalies and downstream cellular defects associated with VWMD.
2025-03-19 | GSE252362 | GEO
Project description:Janthinobacterium lividum strain:EIF2 Genome sequencing
| PRJNA610480 | ENA
Project description:Eukaryotic translation initiation factor 2B (eIF2B) is a heteropentameric guanine nucleotide exchange factor that converts protein synthesis initiation factor 2 (eIF2) from a GDP-bound form to the active eIF2-GTP complex. Cellular stress can repress translation initiation by activating kinases capable of phosphorylating the alpha subunit of eIF2 (eIF2α), which sequesters eIF2B to prevent exchange activity. Previously, we demonstrated that tumor cells are sensitive to viral replication, possibly due to the occurrence of defects in eIF2B that overcome the inhibitory effects of eIF2α phosphorylation. To extend this analysis, we have investigated the importance of eIF2Bα function and report that this subunit can functionally substitute for its counterpart, GCN3, in yeast. In addition, a variant of mammalian eIF2Bα harboring a point mutation (T41A) was able overcome translational inhibition invoked by amino acid depravation, which activates Saccharomyces cerevisiae GCN2 to phosphorylate the yeast eIF2α homolog SUI2. Significantly, we also demonstrate that the loss of eIF2Bα, or the expression of the T41A variant in mammalian cells, is sufficient to neutralize the consequences of eIF2α phosphorylation and render normal cells susceptible to virus infection. Our data emphasize the importance of eIF2Bα in mediating the eIF2 kinase translation-inhibitory activity and may provide insight into the complex nature of viral oncolysis.
| S-EPMC3196436 | biostudies-literature
Project description:In eukaryotic translation initiation, the eIF2.GTP/Met-tRNA(i)(Met) ternary complex (TC) binds the eIF3/eIF1/eIF5 complex to form the multifactor complex (MFC), whereas eIF2.GDP binds the pentameric factor eIF2B for guanine nucleotide exchange. eIF5 and the eIF2Bvarepsilon catalytic subunit possess a conserved eIF2-binding site. Nearly half of cellular eIF2 forms a complex with eIF5 lacking Met-tRNA(i)(Met), and here we investigate its physiological significance. eIF5 overexpression increases the abundance of both eIF2/eIF5 and TC/eIF5 complexes, thereby impeding eIF2B reaction and MFC formation, respectively. eIF2Bvarepsilon mutations, but not other eIF2B mutations, enhance the ability of overexpressed eIF5 to compete for eIF2, indicating that interaction of eIF2Bvarepsilon with eIF2 normally disrupts eIF2/eIF5 interaction. Overexpression of the catalytic eIF2Bvarepsilon segment similarly exacerbates eIF5 mutant phenotypes, supporting the ability of eIF2Bvarepsilon to compete with MFC. Moreover, we show that eIF5 overexpression does not generate aberrant MFC lacking tRNA(i)(Met), suggesting that tRNA(i)(Met) is a vital component promoting MFC assembly. We propose that the eIF2/eIF5 complex represents a cytoplasmic reservoir for eIF2 that antagonizes eIF2B-promoted guanine nucleotide exchange, enabling coordinated regulation of translation initiation.
| S-EPMC1589998 | biostudies-literature