EIF2B-capturing viral protein NSs suppresses the integrated stress response
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PROVIDER: PRJNA731488 | ENA |
REPOSITORIES: ENA
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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: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:Transcriptomic profiling of a eIF2B mutant mouse with a chronic Integrated Stress Response
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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:Anti-viral host factors are essential for controlling SARS-CoV-2 infection but remain largely unknown due to the biases of previous large-scale studies toward pro-viral host factors. To fill this gap, we performed a genome-wide CRISPR dropout screen and integrated analyses of the multi-omics data of the CRISPR screen, genome-wide association studies, single-cell RNA-seq, and host-host/viral protein-protein/RNA interactome. We identified many anti-viral host genes that were missed by previous studies, including the components of V-ATPases, ESCRT, and N-glycosylation pathways that inhibited viral entry/replication. We also identified the cohesin complex as a novel antiviral pathway, supporting an important role of three-dimensional chromatin organization in mediating host-viral interaction. Furthermore, we discovered an anti-viral transcription factor KLF5, a regulator of sphingolipid metabolism, which was up-regulated and harbored genetic variations linked to COVID-19 patients with severe symptoms. Our analyses provide a resource for understanding the host antiviral network for combating SARS-CoV-2 and may help develop new therapeutic strategies.
2023-08-08 | GSE209750 | GEO
Project description:Comparison of genes induced during activation of the Integrated Stress Response by tunicamycin or following AP20187 induced dimerization of a Fv2E-PERK chimera in wildtype cells and cells carrying mutations in key ISR signaling molecules. Keywords: other
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Project description:Retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), including RIG-I (encoded by Ddx58) and MDA5 (melanoma-differentiation-associated gene 5, encoded by Ifih1), are crucial for initiating antiviral responses. Endogenous retroviral elements (ERVs) are transposable elements derived from exogenous retrovirus that integrated into the genome. KRAB-associated protein 1 (KAP1) is a master epigenetic suppressor of ERVs, and thereby protects cells from detrimental genome instability. Increased ERV transcripts are sensed by RLRs and trigger innate immune signaling. However, whether KAP1 could directly control RLRs activity remain unclear. Here we show that KAP1 attenuates RNA viral infection induced type I IFNs and facilitates viral replication by inhibiting RIG-I/MDA5 expression in primary peritoneal macrophages of C57BL/6J mice. Kap1 deficiency increased IFN-β expression and inhibited VSV replication in C57BL/6J mice in vivo. Mechanistically, KAP1 binds to the promoter regions of Ddx58 and Ifih1, and promotes the establishment of repressive histone marks in primary peritoneal macrophages of C57BL/6J mice. Concordantly, KAP1 suppresses the expression of RIG-I and MDA5 at transcriptional level in primary peritoneal macrophages of C57BL/6J mice. Our results establish that KAP1 epigenetically suppresses host antiviral responses by direct targeting RIG-1 and MDA5, and thus facilitates the immune escape of RNA viruses.
2021-07-28 | GSE178443 | GEO