Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA274997 | ENA |
REPOSITORIES: ENA
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Project description:We recently identified ISRIB as a potent inhibitor of the integrated stress response (ISR). ISRIB renders cells resistant to the effects of eIF2α phosphorylation and enhances long-term memory in rodents (10.7554/eLife.00498). Here we show by genome-wide in vivo ribosome profiling that translation of a restricted subset of mRNAs is induced upon ISR activation. ISRIB substantially reversed the translational effects elicited by phosphorylation of eIF2α and induced no major changes in translation or mRNA levels in unstressed cells. eIF2α phosphorylation-induced stress granule (SG) formation was blocked by ISRIB. Strikingly, ISRIB addition to stressed cells with pre-formed SGs induced their rapid disassembly, liberating mRNAs into the actively translating pool. Restoration of mRNA translation and modulation of SG dynamics may be an effective treatment of neurodegenerative diseases characterized by eIF2α phosphorylation, SG formation and cognitive loss. Ribosome profiling with paired RNA-seq
2015-02-27 | E-GEOD-65778 | biostudies-arrayexpress
Project description:We recently identified ISRIB as a potent inhibitor of the integrated stress response (ISR). ISRIB renders cells resistant to the effects of eIF2α phosphorylation and enhances long-term memory in rodents (10.7554/eLife.00498). Here we show by genome-wide in vivo ribosome profiling that translation of a restricted subset of mRNAs is induced upon ISR activation. ISRIB substantially reversed the translational effects elicited by phosphorylation of eIF2α and induced no major changes in translation or mRNA levels in unstressed cells. eIF2α phosphorylation-induced stress granule (SG) formation was blocked by ISRIB. Strikingly, ISRIB addition to stressed cells with pre-formed SGs induced their rapid disassembly, liberating mRNAs into the actively translating pool. Restoration of mRNA translation and modulation of SG dynamics may be an effective treatment of neurodegenerative diseases characterized by eIF2α phosphorylation, SG formation and cognitive loss.
2015-02-27 | GSE65778 | GEO
Project description:Endoplasmic reticulum (ER) stress triggers an adaptive response which fosters tumor cell survival and resilience to stress conditions. Activation of the endoplasmic reticulum stress response, through its PERK branch, promotes the phosphorylation of the α-subunit of translation initiation factor eIF2alpha, thereby repressing general protein translation and selectively augmenting the translation of ATF4 with the downstream CHOP transcription factor and the protein disulfide oxidase ERO1. Here, we show that ISRIB, a small molecule, which inhibits the action of the phosphorylated α-subunit of eIF2, thereby activating protein translation, synergistically interacts with the genetic deficiency of protein disulfide oxidase ERO1 enfeebling tumor growth and spreading. ISRIB represses CHOP signal but surprisingly does not inhibit ERO1. Mechanistically, ISRIB increases the ER protein load with a prominent perturbing effect on ERO1 deficient Triple-Negative breast cells, which have adapted to live with low client protein load, while ERO1 deficiency selectively impairs VEGF-dependent angiogenesis. Strikingly, ERO1-deficient Triple Negative Breast Cancer xenografts have augmented ER stress response and PERK branch. In vivo, ISRIB synergistically with ERO1 deficiency inhibits the growth of Triple-Negative Breast cancer xenografts by impairing proliferation and angiogenesis, while it is not effective on the xenograft counterparts with ERO1. In summary, these results demonstrate that ISRIB together with ERO1 deficiency synergistically shatters a feature of the adaptive ER stress response while ERO1 deficiency selectively impairs angiogenesis in tumors, thereby together promoting tumor cytotoxicity. Therefore, our findings suggest two surprising findings in breast tumors: ERO1 is not regulated via CHOP and ISRIB represents a therapeutic option to efficiently inhibit tumor progression in those tumors with limited ERO1 and high PERK.
2022-07-20 | E-MTAB-11313 | biostudies-arrayexpress
Project description:All cells and organisms exhibit stress-coping mechanisms to ensure survival. Cytoplasmic protein-RNA assemblies termed stress granules are increasingly recognized to promote cellular survival under stress. Thus, they might represent tumor vulnerabilities that are currently poorly explored. The translation-inhibitory eIF2α kinases are established as main drivers of stress granule assembly. Using a systems approach, we identify the translation enhancers PI3K and MAPK/p38 as pro-stress-granule-kinases. They act through the metabolic master regulator mammalian target of rapamycin complex 1 (mTORC1) to promote stress granule assembly. When highly active, PI3K is the main driver of stress granules; however, the impact of p38 becomes apparent as PI3K activity declines. PI3K and p38 thus act in a hierarchical manner to drive mTORC1 activity and stress granule assembly. Of note, this signaling hierarchy is also present in human breast cancer tissue. Importantly, only the recognition of the PI3K-p38 hierarchy under stress enabled the discovery of p38’s role in stress granule formation. In summary, we assign a new pro-survival function to the key oncogenic kinases PI3K and p38, as they hierarchically promote stress granule formation.
2020-01-03 | MODEL2001030002 | BioModels
Project description:Stress granules are dynamic cytoplasmic ribonucleoprotein granules that assemble in response to cellular stress. Aberrant formation of stress granules has been linked to neurodegenerative diseases. However, the molecular mechanisms underlying the initiation of stress granules remain elusive. Here we report that the brain-enriched protein kinase FAM69C promotes stress granule assembly through phosphorylation of eukaryotic translation initiation factor 2 (eIF2α). FAM69C physically interacts with eIF2α and functions as a stress-specific kinase for eIF2α, leading to stress-induced protein translation arrest and stress granule assembly. Primary microglia derived from Fam69c knockout mice exhibit aberrant stress granule assembly in response to oxidative stress and ATP. Defective stress granule assembly in microglia correlates with the formation of ASC specks and NLRP3 inflammasome activation, whereas induction of stress granule precludes inflammasome formation. Consistently, increased NLRP3 levels, caspase-1 cleavage and Il18 expression corroborate microglia-associated neuroinflammation in aged Fam69c knockout mice. Our study demonstrates that FAM69C is critical for stress granule assembly and suggests its role in the regulation of microglia function.
2023-04-21 | PXD037697 | Pride
Project description:Translational control of gene expression is an important regulator of adult stem cell quiescence, activation and self-renewal. In skeletal muscle, quiescent satellite cells maintain low levels of protein synthesis, mediated in part through the phosphorylation of eIF2α (P-eIF2α). Pharmacological inhibition of the eIF2α phosphatase with the small molecule sal003 maintains P-eIF2α and permits the expansion of satellite cells ex vivo. Paradoxically, P-eIF2α also increases the translation of specific mRNAs, which is mediated by P-eIF2α-dependent read-through of inhibitory upstream open reading frames (uORFs). Here, we ask whether P-eIF2α-dependent mRNA translation enables expansion of satellite cells. Using transcriptomic and proteomic analyses, we show a number of genes associated with the assembly of the spindle pole to be upregulated at the level of protein, without corresponding change in mRNA levels, in satellite cells expanded in the presence of sal003. We show that uORFs in the 5′ UTR of mRNA for the mitotic spindle stability gene Tacc3 direct P-eIF2α-dependent translation. Satellite cells deficient for TACC3 exhibit defects in expansion, self-renewal and regeneration of skeletal muscle.
2021-01-14 | GSE164774 | GEO
Project description:In response to stress, eukaryotes activate the integrated stress response (ISR) via phosphorylation of eIF2α to promote the translation of pro-survival effector genes, such as GCN4 in yeast. Complementing the ISR is the Target of Rapamycin (TOR) pathway, which regulates eIF4E function. Here we probe translational control in the absence of eIF4E in Saccharomyces cerevisiae. Intriguingly, we find that loss of eIF4E leads to de-repression of GCN4 translation. In addition, we find that de-repression of GCN4 translation is neither accompanied by eIF2α phosphorylation nor reduction in initiator ternary complex. Our data suggest that when eIF4E levels are depleted, GCN4 translation is de-repressed via a unique mechanism that may involve faster scanning by the small ribosome subunit due to increased local concentration of eIF4A. Overall, our findings suggest that relative levels of eIF4F components are key to ribosome dynamics and may play important roles in translational control of gene expression.
2023-01-25 | GSE223465 | GEO
Project description:The eIF2 initiation complex is central to maintaining a functional translation machinery. Extreme stress such as life-threatening sepsis exposes vulnerabilities in this tightly regulated system, resulting in an imbalance between the opposing actions of kinases and phosphatases on the main regulatory subunit eIF2α. Here, we report that translation shutdown is a hallmark of established sepsis-induced kidney injury brought about by excessive eIF2α phosphorylation and sustained by blunted expression of the counterregulatory phosphatase subunit Ppp1r15a. We determined that the blunted Ppp1r15a expression persists because of the presence of an upstream open reading frame (uORF). Overcoming this barrier with genetic approaches enabled the derepression of Ppp1r15a, salvaged translation and improved kidney function in an endotoxemia model. We also found that the loss of this uORF has broad effects on the composition and phosphorylation status of the immunopeptidome that extended beyond the eIF2α axis. Collectively, our findings define the breath and potency of the highly conserved Ppp1r15a uORF and provide a paradigm for the design of uORF-based translation rheostat strategies. The ability to accurately control the dynamics of translation during sepsis will open new paths for the development of therapies at codon level precision.
2021-12-22 | GSE191262 | GEO
Project description:mRNA translation plays a major role in homeostasis, whereas its dysregulation underpins a variety of pathological states including cancer, metabolic syndrome and neurological disorders. Ternary complex (TC) and eIF4F complex assembly are two major rate-limiting steps in translation initiation that are thought to be regulated by eIF2α phosphorylation, and the mTOR/4E-BP pathway, respectively2. However, how TC and eIF4F assembly are coordinated remains largely unknown. Using polysome-profiling, we show that on a genome-wide scale mTOR suppresses translation of mRNAs, which are translationally activated under short-term ER stress when TC recycling is attenuated by eIF2α phosphorylation. During acute nutrient or growth factor stimulation, mTORC1 induces eIF2β phosphorylation, which increases recruitment of NCK1 to eIF2, decreases eIF2α phosphorylation and bolsters TC recycling. Accordingly, eIF2β appears to act as a previously unidentified mediator of mTORC1 on protein synthesis and proliferation. In addition, we demonstrate a formerly undocumented role for CK2 in regulation of translation initiation, whereby CK2 stimulates phosphorylation of eIF2β and simultaneously bolsters eIF4F complex assembly via the mTORC1/4E-BP pathway. These findings imply a previously unrecognized mode of translation regulation whereby mTORC1 and CK2 coordinate TC and eIF4F complex assembly to stimulate cell proliferation.
2016-04-01 | GSE76766 | GEO
Project description:Stress granule and inflammasome assembly determine contrasting fates of stressed cells. FAM69C is a brain-enriched kinase associated with neurodegenerative diseases, but its biological functions are still largely unknown. Here we show that FAM69C plays an important role in the regulation of stress responses through promoting stress granule assembly and suppressing inflammasome activation. In response to ATP, a common inflammasome activator, mouse primary microglia, and BV-2 cells form stress granules. FAM69C deficiency hastens inflammasome activation in mouse microglia, which is accompanied by inhibited stress granule assembly. FAM69C promotes the assembly of stress granules and halts protein translation under stress. Aged Fam69c knockout mice show increased neuroinflammation and ASC specks formation. We further find that FAM69C physically phosphorylates eIF2α and promotes stress granule assembly. Our data reveal that FAM69C promotes stress granule assembly under stress and suppresses inflammasome formation in microglia, suggesting that FAM69C may be a potential therapeutic target for neurodegenerative diseases.
2022-10-05 | GSE214646 | GEO