scholarly journals Mammalian orthoreovirusinfection is enhanced in cells pre-treated with sodium arsenite

2019 ◽  
Author(s):  
Michael M. Lutz ◽  
Megan P. Worth ◽  
Meleana M. Hinchman ◽  
John S. L. Parker ◽  
Emily D. Ledgerwood
Keyword(s):  
Stress Response ◽  
Heat Shock ◽  
Protein Expression ◽  
Stress Responses ◽  
Sodium Arsenite ◽  
Integrated Stress Response ◽  
Reovirus Infection ◽  
Cellular Stress Responses ◽  
Pre Treatment ◽  
Reovirus Replication

ABSTRACTFollowing reovirus infection, cells activate stress responses that repress canonical cellular translation as a mechanism to limit production of progeny virions. This includes the formation of stress granules (SG) that sequester translationally-stalled cellular transcripts, translation initiation factors, ribosomal proteins, and RNA binding proteins until conditions improve and translation can resume. Work by others suggests that these cellular stress responses, which are part of the integrated stress response, may benefit rather than repress reovirus replication. In agreement with this, we report that stressing cells prior to infection with sodium arsenite (SA), a robust inducer of SG and activator of eIF2α kinases, enhanced viral protein expression, percent infectivity and viral titer in SA-treated cells compared to untreated cells. SA-mediated enhancement of reovirus replication was not strain-specific, but was cell-type specific. While pre-treatment of cells with SA offered the greatest enhancement, treatment of infected cultures as late as 4 h post infection resulted in an increase in the percent of cells infected. SA activates the HRI kinase, which phosphorylates eIF2α and subsequently induces SG formation. Other stresses, such as heat shock (HS) and osmotic shock also activate HRI. Heat shock of cells prior to reovirus infection readily induced SG in greater than 85% of cells. Although HS pre-treatment had no effect on the percentage of infected cells or viral yield, it did enhance viral protein expression. These data suggest that SA pre-treatment perturbs the cell in a way that is beneficial for reovirus and that neither HRI activation nor SG induction is sufficient for reovirus infection enhancement.SIGNIFICANCEAll viruses rely on the host translational machinery for the synthesis of viral proteins. In response to viral infection, cells activate the integrated stress response resulting in the phosphorylation of eIF2α and translation shutoff. Despite this, reovirus replicates to reduced titers in the absence of this response. In this work, we report that sodium arsenite activation of the integrated stress response prior to virus inoculation enhances virus infectivity, protein expression and titer. Together, these data suggest that modulation of conserved cellular stress responses can alter reovirus replication.

scholarly journals Mammalian orthoreovirus Infection is Enhanced in Cells Pre-Treated with Sodium Arsenite

Viruses ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 563 ◽  
Author(s):  
Michael M. Lutz ◽  
Megan P. Worth ◽  
Meleana M. Hinchman ◽  
John S.L. Parker ◽  
Emily D. Ledgerwood
Keyword(s):  
Protein Expression ◽  
Stress Responses ◽  
Viral Protein ◽  
Sodium Arsenite ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Viral Protein Expression ◽  
Viral Yield ◽  
Pre Treatment ◽  
In Cells

Following reovirus infection, cells activate stress responses that repress canonical translation as a mechanism to limit progeny virion production. Work by others suggests that these stress responses, which are part of the integrated stress response (ISR), may benefit rather than repress reovirus replication. Here, we report that compared to untreated cells, treating cells with sodium arsenite (SA) to activate the ISR prior to infection enhanced viral protein expression, percent infectivity, and viral titer. SA-mediated enhancement was not strain-specific, but was cell-type specific. While SA pre-treatment of cells offered the greatest enhancement, treatment within the first 4 h of infection increased the percent of cells infected. SA activates the heme-regulated eIF2α (HRI) kinase, which phosphorylates eukaryotic translation initiation factor 2 alpha (eIF2α) to induce stress granule (SG) formation. Heat shock (HS), another activator of HRI, also induced eIF2α phosphorylation and SGs in cells. However, HS had no effect on percent infectivity or viral yield but did enhance viral protein expression. These data suggest that SA pre-treatment perturbs the cell in a way that is beneficial for reovirus and that this enhancement is independent of SG induction. Understanding how to manipulate the cellular stress responses during infection to enhance replication could help to maximize the oncolytic potential of reovirus.

scholarly journals Structural Variants of poly(alkylcyanoacrylate) Nanoparticles Differentially Affect LC3 and Autophagic Cargo Degradation

2020 ◽  
Vol 16 (4) ◽  
pp. 432-445
Author(s):  
Tonje Sønstevold ◽  
Nikolai Engedal ◽  
Ýrr Mørch ◽  
Tore Geir Iversen ◽  
Tore Skotland ◽  
...  
Keyword(s):  
Stress Response ◽  
Er Stress ◽  
Stress Responses ◽  
Drug Carrier ◽  
Drug Carriers ◽  
Autophagic Flux ◽  
Integrated Stress Response ◽  
Alkyl Side Chains ◽  
Cellular Stress Responses ◽  
Autophagic Degradation

Nanoparticle drug carriers trigger a variety of cellular stress responses, including ER stress and antioxidant responses, but may also affect the intracellular degradative pathway autophagy. This can impose profound effects on drug delivery, cellular treatment responses, and nanoparticle cytotoxicity. We recently demonstrated that even small variations in the alkyl side chains of poly(alkylcyanoacrylate) (PACA) drug carrier nanoparticles, namely butyl (PBCA), ethylbutyl (PEBCA), or octyl (POCA), differentially induce ER stress and redox imbalance in human cell lines. Here, we systematically investigate how these PACA variants affect autophagy. Interestingly, treatment with PEBCA or POCA particles led to intracellular accumulation of the autophagosome marker LC3-II, but via different mechanisms. PEBCA induced an integrated stress response-and ATF4-mediated increase in LC3B mRNA, whereas POCA blocked autophagic degradation of LC3-II and long-lived proteins in bulk. PBCA also increased LC3B mRNA via the integrated stress response and ATF4, but unlike PEBCA, it inhibited LC3 lipidation and autophagic cargo degradation. Our data demonstrate that even subtle variations in NP structure can have profoundly different impacts on autophagy, and that careful monitoring of autophagic flux and cargo degradation is critical for drawing accurate conclusions. Our findings have important implications for the choice of PACA monomer in different therapeutic settings.

scholarly journals Flavonoids: Potential Candidates for the Treatment of Neurodegenerative Disorders

Biomedicines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 99
Author(s):  
Shweta Devi ◽  
Vijay Kumar ◽  
Sandeep Kumar Singh ◽  
Ashish Kant Dubey ◽  
Jong-Joo Kim
Keyword(s):  
Stress Response ◽  
Stress Responses ◽  
Neurodegenerative Disorders ◽  
Cell Damage ◽  
Cellular Stress ◽  
Clinical Manifestations ◽  
Cellular Stress Response ◽  
Dramatic Rise ◽  
Cellular Stress Responses

Neurodegenerative disorders, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), Amyotrophic lateral sclerosis (ALS), and Huntington’s disease (HD), are the most concerning disorders due to the lack of effective therapy and dramatic rise in affected cases. Although these disorders have diverse clinical manifestations, they all share a common cellular stress response. These cellular stress responses including neuroinflammation, oxidative stress, proteotoxicity, and endoplasmic reticulum (ER)-stress, which combats with stress conditions. Environmental stress/toxicity weakened the cellular stress response which results in cell damage. Small molecules, such as flavonoids, could reduce cellular stress and have gained much attention in recent years. Evidence has shown the potential use of flavonoids in several ways, such as antioxidants, anti-inflammatory, and anti-apoptotic, yet their mechanism is still elusive. This review provides an insight into the potential role of flavonoids against cellular stress response that prevent the pathogenesis of neurodegenerative disorders.

scholarly journals Monogenic Diabetes and Integrated Stress Response Genes Display Altered Gene Expression in Type 1 Diabetes

2021 ◽  
Author(s):  
Helmut Hiller ◽  
Dawn E. Beachy ◽  
Joseph J. Lebowitz ◽  
Stefanie Engler ◽  
Justin R. Mason ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Stress Response ◽  
Stress Responses ◽  
Disease Process ◽  
Monogenic Diabetes ◽  
Integrated Stress Response ◽  
Altered Expression ◽  
Increased Risk ◽  
Gene And Protein Expression

Type 1 diabetes has a multifactorial autoimmune etiology, involving environmental prompts and polygenic predisposition. We hypothesized that pancreata from individuals with and at risk for type 1 diabetes would exhibit dysregulated expression of genes associated with monogenic forms of diabetes caused by non-redundant single-gene mutations. Employing a “monogenetic transcriptomic strategy,” we measured the expression of these genes in human type 1 diabetes, autoantibody positive (autoantibody+), and control pancreas tissues using RTqPCR in accordance with the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. Gene and protein expression were visualized <i>in situ</i> using immunofluorescence, RNAScope, and confocal microscopy. Two-dozen monogenic diabetes genes showed altered expression in human pancreata from individuals with type 1 diabetes versus unaffected controls. Six of these genes also saw dysregulation in pancreata from autoantibody+ persons at increased-risk for type 1 diabetes. As a subset of these genes are related to cellular stress responses, we measured integrated stress response (ISR) genes and identified 20 with altered expression in type 1 diabetes pancreata, including three of the four eIF2a-dependent kinases. Equally intriguing, we observed significant repression of the three arms of the ISR in autoantibody+ pancreata. Collectively, these efforts suggest monogenic diabetes and ISR genes are dysregulated early in the type 1 diabetes disease process and likely contribute to the disorder’s pathogenesis.

scholarly journals Translational induction of ATF4 during integrated stress response requires noncanonical initiation factors eIF2D and DENR

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Deepika Vasudevan ◽  
Sarah D. Neuman ◽  
Amy Yang ◽  
Lea Lough ◽  
Brian Brown ◽  
...  
Keyword(s):  
Stress Response ◽  
Er Stress ◽  
Stress Responses ◽  
Rna Binding ◽  
Open Reading Frames ◽  
Binding Motif ◽  
Integrated Stress Response ◽  
Developmental Defects ◽  
Initiation Factors

Abstract The Integrated Stress Response (ISR) helps metazoan cells adapt to cellular stress by limiting the availability of initiator methionyl-tRNA for translation. Such limiting conditions paradoxically stimulate the translation of ATF4 mRNA through a regulatory 5′ leader sequence with multiple upstream Open Reading Frames (uORFs), thereby activating stress-responsive gene expression. Here, we report the identification of two critical regulators of such ATF4 induction, the noncanonical initiation factors eIF2D and DENR. Loss of eIF2D and DENR in Drosophila results in increased vulnerability to amino acid deprivation, susceptibility to retinal degeneration caused by endoplasmic reticulum (ER) stress, and developmental defects similar to ATF4 mutants. eIF2D requires its RNA-binding motif for regulation of 5′ leader-mediated ATF4 translation. Consistently, eIF2D and DENR deficient human cells show impaired ATF4 protein induction in response to ER stress. Altogether, our findings indicate that eIF2D and DENR are critical mediators of ATF4 translational induction and stress responses in vivo.

scholarly journals Protein Expression Profiles of Chlamydia pneumoniae in Models of Persistence versus Those of Heat Shock Stress Response

2006 ◽  
Vol 74 (7) ◽  
pp. 3853-3863 ◽  
Author(s):  
Sanghamitra Mukhopadhyay ◽  
Richard D. Miller ◽  
Erin D. Sullivan ◽  
Christina Theodoropoulos ◽  
Sarah A. Mathews ◽  
...  
Keyword(s):  
Stress Response ◽  
Heat Shock ◽  
Protein Expression ◽  
Chlamydia Pneumoniae ◽  
Expression Profiles ◽  
Stress Component ◽  
Expression Patterns ◽  
Heat Shock Stress ◽  
Shock Stress

ABSTRACT Chlamydia pneumoniae is an obligate intracellular pathogen that causes both acute and chronic human disease. Several in vitro models of chlamydial persistence have been established to mimic chlamydial persistence in vivo. We determined the expression patterns of 52 C. pneumoniae proteins, representing nine functional subgroups, from the gamma interferon (IFN-γ) treatment (primarily tryptophan limitation) and iron limitation (IL) models of persistence compared to those following heat shock (HS) at 42°C. Protein expression patterns of C. pneumoniae persistence indicates a strong stress component, as evidenced by the upregulation of proteins involved in protein folding, assembly, and modification. However, it is clearly more than just a stress response. In IFN persistence, but not IL or HS, amino acid and/or nucleotide biosynthesis proteins were found to be significantly upregulated. In contrast, proteins involved in the biosynthesis of cofactors, cellular processes, energy metabolism, transcription, and translation showed an increased in expression in only the IL model of persistence. These data represent the most extensive protein expression study of C. pneumoniae comparing the chlamydial heat shock stress response to two models of persistence and identifying the common and unique protein level responses during persistence.

scholarly journals Reovirus Induces and Benefits from an Integrated Cellular Stress Response

2006 ◽  
Vol 80 (4) ◽  
pp. 2019-2033 ◽  
Author(s):  
Jennifer A. Smith ◽  
Stephen C. Schmechel ◽  
Arvind Raghavan ◽  
Michelle Abelson ◽  
Cavan Reilly ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Stress Response ◽  
Stress Responses ◽  
Cellular Stress Response ◽  
Initiation Factor ◽  
Viral Protein Synthesis ◽  
Protein Levels ◽  
Eif2α Phosphorylation ◽  
Infected Cells ◽  
Reovirus Replication

ABSTRACT Following infection with most reovirus strains, viral protein synthesis is robust, even when cellular translation is inhibited. To gain further insight into pathways that regulate translation in reovirus-infected cells, we performed a comparative microarray analysis of cellular gene expression following infection with two strains of reovirus that inhibit host translation (clone 8 and clone 87) and one strain that does not (Dearing). Infection with clone 8 and clone 87 significantly increased the expression of cellular genes characteristic of stress responses, including the integrated stress response. Infection with these same strains decreased transcript and protein levels of P58IPK, the cellular inhibitor of the eukaryotic initiation factor 2α (eIF2α) kinases PKR and PERK. Since infection with host shutoff-inducing strains of reovirus impacted cellular pathways that control eIF2α phosphorylation and unphosphorylated eIF2α is required for translation initiation, we examined reovirus replication in a variety of cell lines with mutations that impact eIF2α phosphorylation. Our results revealed that reovirus replication is more efficient in the presence of eIF2α kinases and phosphorylatable eIF2α. When eIF2α is phosphorylated, it promotes the synthesis of ATF4, a transcription factor that controls cellular recovery from stress. We found that the presence of this transcription factor increased reovirus yields 10- to 100-fold. eIF2α phosphorylation also led to the formation of stress granules in reovirus-infected cells. Based on these results, we hypothesize that eIF2α phosphorylation facilitates reovirus replication in two ways—first, by inducing ATF4 synthesis, and second, by creating an environment that places abundant reovirus transcripts at a competitive advantage for limited translational components.

scholarly journals A Genomic Catalog of Stress Response Genes in Anaerobic Fungi for Applications in Bioproduction

2021 ◽  
Vol 2 ◽  
Author(s):  
Candice L. Swift ◽  
Nikola G. Malinov ◽  
Stephen J. Mondo ◽  
Asaf Salamov ◽  
Igor V. Grigoriev ◽  
...  
Keyword(s):  
Stress Response ◽  
Heat Shock ◽  
Stress Responses ◽  
Protein Trafficking ◽  
Anaerobic Fungi ◽  
Transcriptional Responses ◽  
Unfolded Protein ◽  
Catalytic Domains ◽  
Stress Response Genes ◽  
Stress Sensing

Anaerobic fungi are a potential biotechnology platform to produce biomass-degrading enzymes. Unlike model fungi such as yeasts, stress responses that are relevant during bioprocessing have not yet been established for anaerobic fungi. In this work, we characterize both the heat shock and unfolded protein responses of four strains of anaerobic fungi (Anaeromyces robustus, Caecomyces churrovis, Neocallimastix californiae, and Piromyces finnis). The inositol-requiring 1 (Ire1) stress sensor, which typically initiates the fungal UPR, was conserved in all four genomes. However, these genomes also encode putative transmembrane kinases with catalytic domains that are similar to the metazoan stress-sensing enzyme PKR-like endoplasmic reticulum kinase (PERK), although whether they function in the UPR of anaerobic fungi remains unclear. Furthermore, we characterized the global transcriptional responses of Anaeromyces robustus and Neocallimastix californiae to a transient heat shock. Both fungi exhibited the hallmarks of ER stress, including upregulation of genes with functions in protein folding, ER-associated degradation, and intracellular protein trafficking. Relative to other fungi, the genomes of Neocallimastigomycetes contained the greatest gene percentage of HSP20 and HSP70 chaperones, which may serve to stabilize their asparagine-rich genomes. Taken together, these results delineate the unique stress response of anaerobic fungi, which is an important step toward their development as a biotechnology platform to produce enzymes and valuable biomolecules.

scholarly journals Integrated stress response restricts macrophage necroptosis

2021 ◽  
Vol 5 (1) ◽  
pp. e202101260
Author(s):  
David E Place ◽  
Parimal Samir ◽  
RK Subbarao Malireddi ◽  
Thirumala-Devi Kanneganti
Keyword(s):  
Cell Death ◽  
Stress Response ◽  
Cell Survival ◽  
Stress Responses ◽  
Critical Role ◽  
Stress Granule ◽  
Integrated Stress Response ◽  
Signaling Axis ◽  
Stressed Cells

The integrated stress response (ISR) regulates cellular homeostasis and cell survival following exposure to stressors. Cell death processes such as apoptosis and pyroptosis are known to be modulated by stress responses, but the role of the ISR in necroptosis is poorly understood. Necroptosis is an inflammatory, lytic form of cell death driven by the RIPK3-MLKL signaling axis. Here, we show that macrophages that have induced the ISR are protected from subsequent necroptosis. Consistent with a reduction in necroptosis, phosphorylation of RIPK1, RIPK3, and MLKL is reduced in macrophages pre-treated with ISR-inducing agents that are challenged with necroptosis-inducing triggers. The stress granule component DDX3X, which is involved in ISR-mediated regulation of pyroptosis, is not required for protecting ISR-treated cells from necroptosis. Disruption of stress granule assembly or knockdown of Perk restored necroptosis in pre-stressed cells. Together, these findings identify a critical role for the ISR in limiting necroptosis in macrophages.

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