Dihydrocapsaicin induces translational repression and stress granule through HRI-eIF2α phosphorylation axis

2021 ◽  
Author(s):  
Koushitak De ◽  
Aravinth Kumar Jayabalan ◽  
Ramesh Mariappan ◽  
Vijay Sankar Ramasamy ◽  
Takbum Ohn
Keyword(s):  
Stress Granule ◽  
Translational Repression ◽  
Eif2α Phosphorylation

scholarly journals The Leader Protein of Theiler's Virus Prevents the Activation of PKR

2019 ◽  
Vol 93 (19) ◽  
Author(s):  
Fabian Borghese ◽  
Frédéric Sorgeloos ◽  
Teresa Cesaro ◽  
Thomas Michiels
Keyword(s):  
Stress Granule ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Wild Type Virus ◽  
Granule Formation ◽  
Double Stranded Rna ◽  
Eif2α Phosphorylation ◽  
Leader Protein ◽  
Infected Cells ◽  
L Proteins

ABSTRACT Leader (L) proteins encoded by cardioviruses are multifunctional proteins that contribute to innate immunity evasion. L proteins of Theiler’s murine encephalomyelitis virus (TMEV), Saffold virus (SAFV), and encephalomyocarditis virus (EMCV) were reported to inhibit stress granule assembly in infected cells. Here, we show that TMEV L can act at two levels in the stress granule formation pathway: on the one hand, it can inhibit sodium arsenite-induced stress granule assembly without preventing eIF2α phosphorylation and, thus, acts downstream of eIF2α; on the other hand, it can inhibit eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation and the consequent PKR-mediated eIF2α phosphorylation. Interestingly, coimmunostaining experiments revealed that PKR colocalizes with viral double-stranded RNA (dsRNA) in cells infected with L-mutant viruses but not in cells infected with the wild-type virus. Furthermore, PKR coprecipitated with dsRNA from cells infected with L-mutant viruses significantly more than from cells infected with the wild-type virus. These data strongly suggest that L blocks PKR activation by preventing the interaction between PKR and viral dsRNA. In infected cells, L also rendered PKR refractory to subsequent activation by poly(I·C). However, no interaction was observed between L and either dsRNA or PKR. Taken together, our results suggest that, unlike other viral proteins, L indirectly acts on PKR to negatively regulate its responsiveness to dsRNA. IMPORTANCE The leader (L) protein encoded by cardioviruses is a very short multifunctional protein that contributes to evasion of the host innate immune response. This protein notably prevents the formation of stress granules in infected cells. Using Theiler’s virus as a model, we show that L proteins can act at two levels in the stress response pathway leading to stress granule formation, the most striking one being the inhibition of eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation. Interestingly, the leader protein appears to inhibit PKR via a novel mechanism by rendering this kinase unable to detect double-stranded RNA, its typical activator. Unlike other viral proteins, such as influenza virus NS1, the leader protein appears to interact with neither PKR nor double-stranded RNA, suggesting that it acts indirectly to trigger the inhibition of the kinase.

scholarly journals Control of HIF-1α Expression by eIF2α Phosphorylation–Mediated Translational Repression

2009 ◽  
Vol 69 (5) ◽  
pp. 1836-1843 ◽  
Author(s):  
Keyi Zhu ◽  
WaiKin Chan ◽  
John Heymach ◽  
Miles Wilkinson ◽  
David J. McConkey
Keyword(s):  
Translational Repression ◽  
Eif2α Phosphorylation

scholarly journals Hydrogen peroxide induces stress granule formation independent of eIF2α phosphorylation

2012 ◽  
Vol 423 (4) ◽  
pp. 763-769 ◽  
Author(s):  
Mohamed M. Emara ◽  
Ken Fujimura ◽  
Daniele Sciaranghella ◽  
Victoria Ivanova ◽  
Pavel Ivanov ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stress Granule ◽  
Granule Formation ◽  
Eif2α Phosphorylation

scholarly journals Large G3BP-induced granules trigger eIF2α phosphorylation

2012 ◽  
Vol 23 (18) ◽  
pp. 3499-3510 ◽  
Author(s):  
Lucas C. Reineke ◽  
Jon D. Dougherty ◽  
Philippe Pierre ◽  
Richard E. Lloyd
Keyword(s):  
Stress Granules ◽  
Stress Granule ◽  
Initiation Factor ◽  
Protein Kinase R ◽  
Translational Machinery ◽  
Initiation Factors ◽  
Eif2α Phosphorylation ◽  
Translation Initiation Factors ◽  
Messenger Ribonucleoprotein ◽  
Translation Apparatus

Stress granules are large messenger ribonucleoprotein (mRNP) aggregates composed of translation initiation factors and mRNAs that appear when the cell encounters various stressors. Current dogma indicates that stress granules function as inert storage depots for translationally silenced mRNPs until the cell signals for renewed translation and stress granule disassembly. We used RasGAP SH3-binding protein (G3BP) overexpression to induce stress granules and study their assembly process and signaling to the translation apparatus. We found that assembly of large G3BP-induced stress granules, but not small granules, precedes phosphorylation of eIF2α. Using mouse embryonic fibroblasts depleted for individual eukaryotic initiation factor 2α (eIF2α) kinases, we identified protein kinase R as the principal kinase that mediates eIF2α phosphorylation by large G3BP-induced granules. These data indicate that increasing stress granule size is associated with a threshold or switch that must be triggered in order for eIF2α phosphorylation and subsequent translational repression to occur. Furthermore, these data suggest that stress granules are active in signaling to the translational machinery and may be important regulators of the innate immune response.

scholarly journals YB-1 regulates tiRNA-induced Stress Granule formation but not translational repression

2016 ◽  
Vol 44 (14) ◽  
pp. 6949-6960 ◽  
Author(s):  
Shawn M. Lyons ◽  
Chris Achorn ◽  
Nancy L. Kedersha ◽  
Paul J. Anderson ◽  
Pavel Ivanov
Keyword(s):  
Stress Granule ◽  
Translational Repression ◽  
Granule Formation ◽  
Induced Stress

scholarly journals Translational Repression of MCL-1 Couples Stress-induced eIF2α Phosphorylation to Mitochondrial Apoptosis Initiation

2007 ◽  
Vol 282 (31) ◽  
pp. 22551-22562 ◽  
Author(s):  
Ralph M. Fritsch ◽  
Günter Schneider ◽  
Dieter Saur ◽  
Melanie Scheibel ◽  
Roland M. Schmid
Keyword(s):  
Translational Repression ◽  
Mitochondrial Apoptosis ◽  
Eif2α Phosphorylation ◽  
Apoptosis Initiation

scholarly journals The Autophagy Protein ATG16L1 Is Required for Sindbis Virus-Induced eIF2α Phosphorylation and Stress Granule Formation

Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 39
Author(s):  
Matthew Jefferson ◽  
Benjamin Bone ◽  
Jasmine L. Buck ◽  
Penny P. Powell
Keyword(s):  
Immune Response ◽  
Protein Synthesis ◽  
Innate Immune Response ◽  
Viral Protein ◽  
Sindbis Virus ◽  
Binding Protein ◽  
Innate Immune ◽  
Stress Granule ◽  
Viral Protein Synthesis ◽  
Eif2α Phosphorylation

Sindbis virus (SINV) infection induces eIF2α phosphorylation, which leads to stress granule (SG) assembly. SINV infection also stimulates autophagy, which has an important role in controlling the innate immune response. The importance of autophagy to virus-induced translation arrest is not well understood. In this study, we show that the autophagy protein ATG16L1 not only regulates eIF2α phosphorylation and the translation of viral and antiviral proteins, but also controls SG assembly. Early in infection (2hpi), capsids were recruited by host factors Cytotoxic Granule-Associated RNA Binding Protein (TIA1), Y-box binding protein 1 (YBX1), and vasolin-containing protein 1 (VCP), to a single perinuclear body, which co-localized with the viral pattern recognition sensors, double stranded RNA-activated protein-kinase R (PKR) and RIG-I. By 6hpi, there was increased eIF2α phosphorylation and viral protein synthesis. However, in cells lacking the autophagy protein ATG16L1, SG assembly was inhibited and capsid remained in numerous small foci in the cytoplasm containing YBX1, TIA1 with RIG-I, and these persisted for over 8hpi. In the absence of ATG16L1, there was little phosphorylation of eIF2α and low levels of viral protein synthesis. Compared to wild type cells, there was potentiated interferon protein and interferon-stimulated gene (ISG) mRNA expression. These results show that ATG16L1 is required for maximum eIF2α phosphorylation, proper SG assembly into a single perinuclear focus, and for attenuating the innate immune response. Therefore, this study shows that, in the case of SINV, ATG16L1 is pro-viral, required for SG assembly and virus replication.

scholarly journals The small molecule ISRIB reverses the effects of eIF2α phosphorylation on translation and stress granule assembly

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Carmela Sidrauski ◽  
Anna M McGeachy ◽  
Nicholas T Ingolia ◽  
Peter Walter
Keyword(s):  
Mrna Translation ◽  
Ribosome Profiling ◽  
Stress Granule ◽  
Long Term Memory ◽  
Mrna Levels ◽  
Eif2α Phosphorylation ◽  
Genome Wide ◽  
Stressed Cells

Previously, we identified ISRIB as a potent inhibitor of the integrated stress response (ISR) and showed that ISRIB makes cells resistant to the effects of eIF2α phosphorylation and enhances long-term memory in rodents (<xref ref-type="bibr" rid="bib54">Sidrauski et al., 2013</xref>). 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.

scholarly journals Infectious bronchitis virus regulates cellular stress granule signaling

2019 ◽  
Author(s):  
Matthew J. Brownsword ◽  
Nicole Doyle ◽  
Michèle Brocard ◽  
Nicolas Locker ◽  
Helena J. Maier
Keyword(s):  
Stress Responses ◽  
Infectious Bronchitis Virus ◽  
Cellular Stress ◽  
Stress Granules ◽  
Stress Granule ◽  
Granule Formation ◽  
Translation Machinery ◽  
Infectious Bronchitis ◽  
Eif2α Phosphorylation ◽  
Cellular Translation

AbstractViruses must hijack cellular translation machinery to efficiently express viral genes. In many cases, this is impeded by cellular stress responses. These stress responses swiftly relocate and repurpose translation machinery, resulting in global inhibition of translation and the aggregation of stalled 48S mRNPs into cytoplasmic foci called stress granules. This results in translational silencing of all mRNAs excluding those beneficial for the cell to resolve the specific stress. For example, expression of antiviral factors is maintained during viral infection. Here we investigated stress granule regulation by Gammacoronavirus infectious bronchitis virus (IBV), which causes the economically important poultry disease, infectious bronchitis. Interestingly, we found that IBV is able to inhibit multiple cellular stress granule signaling pathways whilst at the same time IBV replication also results in induction of seemingly canonical stress granules in a proportion of infected cells. Moreover, IBV infection uncouples translational repression and stress granule formation and both processes are independent of eIF2α phosphorylation. These results provide novel insights into how IBV modulates cellular translation and antiviral stress signaling.

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