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Microplastic has emerged as a global threat owing to its chronic ubiquity and persistence. Microplastics' small size expedites their ingestion at each trophic level causing biomagnification and bioaccumulation, which has raised public concerns. The present study isolated, quantified and characterized the abundance, shape, size, color, and chemical composition of the microplastics from water and sediments of the Hirakud Reservoir through a scanning electron microscope and FTIR. The ecological risk associated with the microplastics was assessed using the species sensitivity distribution (SSD) method to derive the Predicted No-Effect Concentration (PNEC) value and risk quotient (RQ). The abundance of microplastics in the surface water and sediments of the Hirakud Reservoir was estimated at 82-89 particles/L and 159-163 particles/kg, respectively. Fiber-shaped microplastics dominated both surface water (46.21%) and sediment samples (44.86%). Small-sized microplastics (53-300 µm) prevailed in all samples. Color delineation exhibited an abundance of transparent microplastics. Chemical characterization indicated the dominance of polypropylene (38%), followed by high-density polyethylene, low-density polyethylene, and polystyrene. The calculated PNEC value was 3,954 particles/m3, and the RQ was estimated to be 0.02073-0.04122 indicating negligible ecological risk to freshwater species in all the sampling sites.
Sujet(s)
Surveillance de l'environnement , Microplastiques , Polluants chimiques de l'eau , Microplastiques/analyse , Microplastiques/toxicité , Inde , Polluants chimiques de l'eau/analyse , Appréciation des risques , Sédiments géologiques/composition chimique , Sédiments géologiques/analyse , Eau douce/composition chimique , Eau douce/analyseRÉSUMÉ
RNA virus infections have been a leading cause of pandemics. Aided by global warming and increased connectivity, their threat is likely to increase over time. The flaviviruses are one such RNA virus family, and its prototypes such as the Japanese encephalitis virus (JEV), Dengue virus, Zika virus, West Nile virus, etc., pose a significant health burden on several endemic countries. All viruses start off their life cycle with an infected cell, wherein a series of events are set in motion as the virus and host battle for autonomy. With their remarkable capacity to hijack cellular systems and, subvert/escape defence pathways, viruses are able to establish infection and disseminate in the body, causing disease. Using this strategy, JEV replicates and spreads through several cell types such as epithelial cells, fibroblasts, monocytes and macrophages, and ultimately breaches the blood-brain barrier to infect neurons and microglia. The neurotropic nature of JEV, its high burden on the paediatric population, and its lack of any specific antivirals/treatment strategies emphasise the need for biomedical research-driven solutions. Here, we highlight the latest research developments on Japanese encephalitis virus-infected cells and discuss how these can aid in the development of future therapies.
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Virus de l'encéphalite japonaise (espèce) , Flavivirus , Virus du Nil occidental , Infection par le virus Zika , Virus Zika , Enfant , Humains , Virus de l'encéphalite japonaise (espèce)/génétique , Virus de l'encéphalite japonaise (espèce)/métabolisme , Virus du Nil occidental/physiologie , Barrière hémato-encéphaliqueRÉSUMÉ
Background: One-third of all cancer deaths are preventable by alterations in diet. Methods: A case control study was conducted in a Regional Cancer Center in North India to evaluate the relationship of diet with selected gastrointestinal cancers. A total of 171 cases, 151 hospital controls, and 167 healthy controls were interviewed using food frequency questionnaire. Data was analyzed using odds ratio with 95% confidence interval and Chi-square test. Results: Two to three times increased risk of GI cancers was observed with hot and salted tea. Alcohol [OR 2.30 (1.32-4)] and smoking [OR (2.77 (1.77-4.33)] emerged as risk factors in healthy controls among whom freshly prepared food had significant protective effect [OR 0.57 (0.37-0.88)]. Sweet tea showed protective effect in hospital and healthy controls (OR 0.33 and 0.26, respectively). NSAIDS was associated with significantly higher risk of GI cancers. Consumption of dietary fibers decreased risk, which was significant for wheat and pulses but insignificant for rice. Vegetables and fruits showed significant protective effect ranging from 20 to 80% while intake of non-vegetarian foods showed significantly higher odds among controls (OR 2.37-13.4). Odds of GI cancer cases having consumed chutneys and pickles were significantly higher in comparison to healthy controls while consumption of dairy products showed protection. Low and medium intake of mixed spices inclusive of curcumin showed protection (OR 0.13 and 0.39, respectively) while intake of red chillies was associated with 2-30 times significantly higher odds. Conclusions: We have been able to generate baseline evidence of association between diet and selected GI cancers to encourage prevention and further research.
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Régime alimentaire , Tumeurs gastro-intestinales , Humains , Études cas-témoins , Régime alimentaire/effets indésirables , Facteurs de risque , Tumeurs gastro-intestinales/épidémiologie , Tumeurs gastro-intestinales/étiologie , Thé , Odds ratioRÉSUMÉ
The excessive usage of non-renewable resources to produce plastic commodities has incongruously influenced the environment's health. Especially in the times of COVID-19, the need for plastic-based health products has increased predominantly. Given the rise in global warming and greenhouse gas emissions, the lifecycle of plastic has been established to contribute to it significantly. Bioplastics such as polyhydroxy alkanoates, polylactic acid, etc. derived from renewable energy origin have been a magnificent alternative to conventional plastics and reconnoitered exclusively for combating the environmental footprint of petrochemical plastic. However, the economically reasonable and environmentally friendly procedure of microbial bioplastic production has been a hard nut to crack due to less scouted and inefficient process optimization and downstream processing methodologies. Thereby, meticulous employment of computational tools such as genome-scale metabolic modeling and flux balance analysis has been practiced in recent times to understand the effect of genomic and environmental perturbations on the phenotype of the microorganism. In-silico results not only aid us in determining the biorefinery abilities of the model microorganism but also curb our reliance on equipment, raw materials, and capital investment for optimizing the best conditions. Additionally, to accomplish sustainable large-scale production of microbial bioplastic in a circular bioeconomy, extraction, and refinement of bioplastic needs to be investigated extensively by practicing techno-economic analysis and life cycle assessment. This review put forth state-of-the-art know-how on the proficiency of these computational techniques in laying the foundation of an efficient bioplastic manufacturing blueprint, chiefly focusing on microbial polyhydroxy alkanoates (PHA) production and its efficacy in outplacing fossil based plastic products.
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BACKGROUND: Fermented foods are the results of metabolic activities of various microorganisms. People have traditionally known how to culture desirable microorganisms, primarily lactic acid bacteria, yeasts, and filamentous molds, for the manufacture of edible foods. Yeast isolated from home-made mango pickle from Hamirpur, Himachal Pradesh, was assessed for probiotic properties and their enzymatic profiling. RESULTS: Four yeast isolates were isolated out of which P. kudriavzevii Y33 was selected on the basis of high acid tolerance as well as broadest antimicrobial activity. The selected isolate was observed to have high acid tolerance at pH 2 and show strong antimicrobial activity against all the pathogens examined. P. kudriavzevii Y33 can also withstand high bile concentration and showed high viability index, i.e., 95% at concentration of 2% of bile. The isolate was able to demonstrate high cholesterol assimilation in medium containing ox bile and taurocholate, at 88.58 and 86.83%, respectively. The autoaggregation ability of isolate increases with increasing the time of incubation and showed 87% of autoaggregation after 24 h of incubation. P. kudriavzevii Y33 exhibited resistance towards different antibiotics, found to be positive for exopolysaccharide production and showed no hemolytic activity. The isolate was observed to produce several enzymes such as ß-galactosidase, protease, amylase, phytase, and lipase. CONCLUSIONS: The results of the current study revealed that P. kudriavzevii Y33 has various beneficial qualities that suggest it could be used as probiotics. Enzymes produced by yeast isolate help in improving flavor and mineral availability in the fermented products.
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RNA virus infection triggers interferon (IFN) receptor signaling, leading to the activation of hundreds of interferon-stimulated genes (ISGs). Guanylate-binding proteins (GBPs) belong to one such IFN inducible subfamily of guanosine triphosphatases (GTPases) that have been reported to exert broad anti-microbial activity and regulate host defenses against several intracellular pathogens. Here, we investigated the role of human GBP1 (hGBP1) in Japanese encephalitis virus (JEV) infection of HeLa cells in both an IFNγ unprimed and primed environment. We observed enhanced expression of GBP1 both at transcript and protein levels upon JEV infection, and GBP1 association with the virus replication membranes. Depletion of hGBP1 through siRNA had no effect on JEV replication or virus induced cell death in the IFNγ unprimed environment. IFNγ stimulation provided robust protection against JEV infection. Knockdown of GBP1 in the primed environment upregulated expression and phosphorylation of signal transducer and activator of transcription 1 (STAT1) and significantly reduced JEV replication. Depletion of GBP1 in an IFNγ primed environment also inhibited virus replication in human neuroblastoma SH-SH5Y cells. Our data suggests that in the presence of IFNγ, GBP1 displays a proviral role by inhibiting innate immune responses to JEV infection.
Sujet(s)
Virus de l'encéphalite japonaise (espèce) , Encéphalite japonaise , Cellules HeLa , Humains , Interféron gamma/métabolisme , Interférons , Réplication viraleRÉSUMÉ
SARS-CoV-2 evolution has continued to generate variants, responsible for new pandemic waves locally and globally. Varying disease presentation and severity has been ascribed to inherent variant characteristics and vaccine immunity. This study analyzed genomic data from 305 whole genome sequences from SARS-CoV-2 patients before and through the third wave in India. Delta variant was responsible for disease in patients without comorbidity(97%), while Omicron BA.2 caused disease primarily in those with comorbidity(77%). Tissue adaptation studies brought forth higher propensity of Omicron variants to bronchial tissue than lung, contrary to observation in Delta variants from Delhi. Study of codon usage pattern distinguished the prevalent variants, clustering them separately, Omicron BA.2 isolated in February grouped away from December strains, and all BA.2 after December acquired a new mutation S959P in ORF1b (44.3% of BA.2 in the study) indicating ongoing evolution. Loss of critical spike mutations in Omicron BA.2 and gain of immune evasion mutations including G142D, reported in Delta but absent in BA.1, and S371F instead of S371L in BA.1 could possibly be due to evolutionary trade-off and explain very brief period of BA.1 in December 2021, followed by complete replacement by BA.2.
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Maintenance of cellular homeostasis through regulated degradation of proteins and organelles is a defining feature of autophagy. This process itself is tightly regulated in a series of well-defined biochemical reactions governed largely by the highly conserved ATG protein family. Given its crucial role in regulating protein levels under both basal and stress conditions such as starvation and infection, genetic or pharmacological perturbation of autophagy results in massive changes in the cellular proteome and impacts nearly every biological process. Therefore, studying autophagy perturbations at a global scale assumes prime importance. In recent years, quantitative mass spectrometry (MS)-based proteomics has emerged as a powerful approach to explore biological processes through global proteome quantification analysis. Tandem mass tag (TMT)-based MS proteomics is one such robust quantitative technique that can examine relative protein abundances in multiple samples (parallel multiplexing). Investigating autophagy through TMT-based MS approach can give great insights into autophagy-regulated biological processes, protein-protein interaction networks, spatiotemporal protein dynamics, and identification of new autophagy substrates. This chapter provides a detailed protocol for studying the impact of a dysfunctional autophagy pathway on the cellular proteome and pathways in a healthy vs. disease (virus infection) condition using a 16-plex TMT-based quantitative proteomics approach. We also provide a pipeline on data processing and analysis using available web-based tools.
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Protéomique , Spectrométrie de masse en tandem , Autophagie , Protéome/analyse , Protéomique/méthodes , Plan de recherche , Spectrométrie de masse en tandem/méthodesRÉSUMÉ
Microalgae have garnered much contemplation as candidates to fix CO2 into valuable compounds. Although microalgae have been studied to produce various metabolites, they have not yet proved successful for commercialization. Since, handling such problems practically requires satisfying multiple parameters simultaneously, we put forth a multi-parameter optimization strategy to manipulate the carbon metabolism of Scenedesmus sp. to improve biomass production and enhance CO2 fixation to increase the production of fuel-related metabolites. The Box-Behnken design method was applied with CO2 concentration, CO2 sparging time and glucose concentration as independent variables; biomass and total fatty acid methyl ester (total FAME) content were analyzed as response variables. The strain is supplemented with both CO2 and glucose with an aim to enhance carbon flux and rechannel it towards carbon fixation. As per the results obtained in this study, Scenedesmus sp. could effectively exploit high CO2 concentration (15%) for longer duration under high concentration of glucose supplementation (9 g/L) producing a biomass of 635.24 ± 39.9 µg/mL with a high total fatty acid methyl ester (FAME) content of 71.29 ± 4.2 µg/mg, significant acetyl-CoA carboxylase enzyme activity and a favorable fatty acid profile: 35.8% palmitic acid, 10.5% linoleic acid and 30.6% linolenic acid. The carbohydrate content was maximum at 10% CO2 sparged for the longest duration of 90 min under glucose concentration of 9 g/L. This study puts forth an optimal design that can provide evidence on comprehending the carbon assimilation mechanism to enhance production of biomass and biofuels and provide conditions to microalgal species to tolerate CO2 rich flue gas.
Sujet(s)
Microalgues , Scenedesmus , Biomasse , Carbone , Dioxyde de carboneRÉSUMÉ
Advances in proteomics have enabled a comprehensive understanding of host-pathogen interactions. Here we have characterized Japanese encephalitis virus (JEV) infection-driven changes in the mouse embryonic fibroblast (MEF) proteome. Through tandem mass tagging (TMT)-based mass spectrometry, we describe changes in 7.85â% of the identified proteome due to JEV infection. Pathway enrichment analysis showed that proteins involved in innate immune sensing, interferon responses and inflammation were the major upregulated group, along with the immunoproteasome and poly ADP-ribosylation proteins. Functional validation of several upregulated anti-viral innate immune proteins, including an active cGAS-STING axis, was performed. Through siRNA depletion, we describe a crucial role of the DNA sensor cGAS in restricting JEV replication. Further, many interferon-stimulated genes (ISGs) were observed to be induced in infected cells. We also observed activation of TLR2 and inhibition of TLR2 signalling using TLR1/2 inhibitor CU-CPT22-blocked production of inflammatory cytokines IL6 and TNF-α from virus-infected N9 microglial cells. The major proteins that were downregulated by infection were involved in cell adhesion (collagens), transport (solute carrier and ATP-binding cassette transporters), sterol and lipid biosynthesis. Several collagens were found to be transcriptionally downregulated in infected MEFs and mouse brain. Collectively, our data provide a bird's-eye view into how fibroblast protein composition is rewired following JEV infection.
Sujet(s)
Virus de l'encéphalite japonaise (espèce)/physiologie , Encéphalite japonaise/métabolisme , Encéphalite japonaise/virologie , Fibroblastes/métabolisme , Fibroblastes/virologie , Protéome , Animaux , Molécules d'adhérence cellulaire/métabolisme , Lignée cellulaire , Collagène/génétique , Cytokines/génétique , Cytokines/métabolisme , Régulation négative , Encéphalite japonaise/génétique , Encéphalite japonaise/immunologie , Fibroblastes/immunologie , Interactions hôte-pathogène , Immunité innée/génétique , Inflammation , Interférons/immunologie , Métabolisme lipidique , Protéines membranaires/génétique , Protéines membranaires/métabolisme , Protéines de transport membranaire/métabolisme , Souris , Souris de lignée C57BL , Nucleotidyltransferases/génétique , Nucleotidyltransferases/métabolisme , Protéines/métabolisme , Protéomique , Transduction du signal , Récepteur de type Toll-2/génétique , Récepteur de type Toll-2/métabolisme , Régulation positiveRÉSUMÉ
Japanese encephalitis virus (JEV) is a flavivirus, spread by the bite of carrier Culex mosquitoes. The subsequent disease caused is Japanese encephalitis (JE), which is the leading global cause of virus-induced encephalitis. The disease is predominant in the entire Asia-Pacific region with the potential of global spread. JEV is highly neuroinvasive with symptoms ranging from mild fever to severe encephalitis and death. One-third of JE infections are fatal, and half of the survivors develop permanent neurological sequelae. Disease prognosis is determined by a series of complex and intertwined signaling events dictated both by the virus and the host. All flaviviruses, including JEV replicate in close association with ER derived membranes by channelizing the protein and lipid components of the ER. This leads to activation of acute stress responses in the infected cell-oxidative stress, ER stress, and autophagy. The host innate immune and inflammatory responses also enter the fray, the components of which are inextricably linked to the cellular stress responses. These are especially crucial in the periphery for dendritic cell maturation and establishment of adaptive immunity. The pathogenesis of JEV is a combination of direct virus induced neuronal cell death and an uncontrolled neuroinflammatory response. Here we provide a comprehensive review of the JEV life cycle and how the cellular stress responses dictate the pathobiology and resulting immune response. We also deliberate on how modulation of these stress pathways could be a potential strategy to develop therapeutic interventions, and define the persisting challenges.
Sujet(s)
Virus de l'encéphalite japonaise (espèce) , Encéphalite japonaise , Immunité acquise , Animaux , Humains , InflammationRÉSUMÉ
In today's era, we need to replace chemical or physical processes of nanoparticle synthesis with biosynthesis processes to avoid environmental damage. These bioderived nanoparticles can help in addressing the problems of wastewater treatment and biofuels production. This review gives an insight into solving multiple problems using a nano-biorefinery approach in conjugation with wastewater treatment. The major advantage of using a bio-derivative method in nanoparticle synthesis is its low toxicity towards the environment. The current review discusses the development of nanoscience and its biogenic importance. It covers the usage of microalgae for (A) Nanoparticle's biosynthesis (B) Mechanism of nanoparticle biosynthesis (C) Nanoparticles in bio-refinery processes (D) Wastewater treatment with microalgae and bio-derived nanoparticles (E) A hypothetical mechanistic approach, which utilizes the photothermal effect of metallic nanoparticles to extract lipids from the cells without cell damage. The term "cell milking" has been around for quite some time, and the hypothesis discussed in the present study can help in this context. The current hypothesized process can pave ways for futuristic endeavors to conjugate nanoparticles and microalgae for viable and commercial production of biofuel, nanoparticles, and many other molecules.
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Microalgues , Purification de l'eau , Biocarburants/analyse , Biomasse , Phénomènes physiques , Eaux uséesRÉSUMÉ
In the present study, solid-state fermentation (SSF) of four fenugreek cultivars viz. HM-57, AFG-2, RMT-1 and RMT-303 were carried out using Aspergillus awamori and its effect on antioxidant properties, phenolic content and bioactive compounds were studied. Macro (Ca, K, and Na) as well as micro (Fe, Zn, and Cu) elements and in vitro bioavailability of the unfermented fenugreek (UFF) and Aspergillus-fermented fenugreek (AFF) samples were assessed with standard methods. On 5th day, total phenolic and condensed tannin contents showed significant (p ≤ 0.05) increase for all cultivars. Further, HPLC analysis confirmed formation of some new bioactive (vanillin, benzoic acid and catechin) compounds. Similarly, extracts from all AFF also showed an increase in the antioxidant potential such as inhibition of DPPH, hydroxyl free radical scavenging, reducing power, and total antioxidant capacity up to 5th day of SSF. Mineral in AFF were found with enhanced values when compared with respective UFF. In vitro bioavailability of Fe, Zn and Ca was also improved during SSF. Results from the present study may be helpful to food industry in developing new health foods and may provide a rational for development of functional ingredient in preparation of novel nutraceuticals.
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Microtubule-associated protein 1 light chain 3 (MAP1LC3) is a protein with a well-defined function in autophagy, but still incompletely understood roles in several other autophagy-independent processess. Studies have shown MAP1LC3 is a host-dependency factor for the replication of several viruses. Japanese encephalitis virus (JEV), a neurotropic flavivirus, replicates on ER-derived membranes that are marked by autophagosome-negative non-lipidated MAP1LC3 (LC3-I). Depletion of LC3 exerts a profound inhibition on virus replication and egress. Here, we further characterize the role of LC3 in JEV replication, and through immunofluorescence and immunoprecipitation show that LC3-I interacts with the virus capsid protein in infected cells. This association was observed on capsid localized to both the replication complex and lipid droplets (LDs). JEV infection decreased the number of LDs per cell indicating a link between lipid metabolism and virus replication. This capsid-LC3 interaction was independent of the autophagy adaptor protein p62/Sequestosome 1 (SQSTM1). Further, no association of capsid was seen with the Gamma-aminobutyric acid receptor-associated protein family, suggesting that this interaction was specific for LC3. High-resolution protein-protein docking studies identified a putative LC3-interacting region in capsid, 56FTAL59, and other key residues that could mediate a direct interaction between the two proteins.
Sujet(s)
Protéines de capside/métabolisme , Virus de l'encéphalite japonaise (espèce)/physiologie , Gouttelettes lipidiques/métabolisme , Protéines associées aux microtubules/métabolisme , Compartiments de réplication virale/métabolisme , Séquence d'acides aminés , Animaux , Capside/composition chimique , Capside/métabolisme , Protéines de capside/composition chimique , Lignée cellulaire , Virus de l'encéphalite japonaise (espèce)/métabolisme , Interactions hôte-pathogène , Humains , Souris , Simulation de docking moléculaire , Motifs et domaines d'intéraction protéique , Réplication viraleRÉSUMÉ
@#Background & Objectives: Depression, anxiety and suicide are the main psychiatric comorbidities which are more prevalent among persons with epilepsy (PWE). This study aims to determine the prevalence of depression, anxiety and suicidal ideation/behaviour in PWE and to correlate their clinical profile with psychiatric comorbidities in a population in North India. Methods: This study was conducted at Pt. BD Sharma PGIMS, Rohtak Haryana among PWE attending outpatient clinic at the Department of Neurology. A total of 100 eligible PWE were included in this study. The demographic and clinical history was documented. All patients filled up the Hospital anxiety and depression scale (HADS) and Columbia-suicide severity rating scale (C-SSRS) questionnaire. Results: The prevalence of depression and anxiety among PWE was found to be 60% and 70% respectively and the prevalence of suicidal ideation and suicidal behaviour was 42% and 3% respectively among PWE. Female gender, longer duration of epilepsy, higher seizure frequency, temporal lobe epilepsy, polytherapy, uncontrolled epilepsy and drug resistant epilepsy were found to be positively correlated with these psychiatric comorbidities. Conclusion: This study shows that the prevalence of depression, anxiety and suicidal ideation/ behaviour is high among PWE in Haryana, North India. PWE should be screened for these psychiatric comorbidities to improve their quality of life
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Basal autophagy is crucial for maintenance of cellular homeostasis. ATG5 is an essential protein for autophagosome formation, and its depletion has been extensively used as a tool to disrupt autophagy. Here, we characterize the impact of Atg5 deficiency on the cellular proteome of mouse embryonic fibroblasts (MEFs). Using a tandem mass tagging (TMT)-based quantitative proteomics analysis, we observe that 14% of identified proteins show dysregulated levels in atg5-/- MEFs. These proteins were distributed across diverse biological processes, such as cell adhesion, development, differentiation, transport, metabolism, and immune responses. Several of the upregulated proteins were receptors involved in transforming growth factor ß (TGF-ß) signaling, JAK-STAT signaling, junction adhesion, and interferon/cytokine-receptor interactions and were validated as autophagy substrates. Nearly equal numbers of proteins, including several lysosomal proteins and enzymes, were downregulated, suggesting a complex role of autophagy/ATG5 in regulating their levels. The atg5-/- MEFs had lower levels of key immune sensors and effectors, including Toll-like receptor 2 (TLR2), interferon regulatory factor 3 (IRF3), IRF7, MLKL, and STAT1/3/5/6, which were restored by reexpression of ATG5. While these cells could efficiently mount a type I interferon response to the double-stranded RNA (dsRNA) mimic poly(I·C), they were compromised in their inflammatory response to the bacterial pathogen-associated molecular patterns (PAMPs) lipopolysaccharide (LPS) and Pam3CSK4. Transcriptional activation and secretion of interleukin-6 (IL-6) in these cells could be recovered by ATG5 expression, supporting the role of autophagy in the TLR2-induced inflammatory response. This study provides a key resource for understanding the effect of autophagy/ATG5 deficiency on the fibroblast proteome.IMPORTANCE Autophagy performs housekeeping functions for cells and maintains a functional mode by degrading damaged proteins and organelles and providing energy under starvation conditions. The process is tightly regulated by the evolutionarily conserved Atg genes, of which Atg5 is one such crucial mediator. Here, we have done a comprehensive quantitative proteome analysis of mouse embryonic fibroblasts that lack a functional autophagy pathway (Atg5 knockout). We observe that 14% of the identified cellular proteome is remodeled, and several proteins distributed across diverse cellular processes with functions in signaling, cell adhesion, development, and immunity show either higher or lower levels under autophagy-deficient conditions. These cells have lower levels of crucial immune proteins that are required to mount a protective inflammatory response. This study will serve as a valuable resource to determine the role of autophagy in modulating specific protein levels in cells.
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Diphenyleneiodonium (DPI) and N-acetyl-l-cysteine (NAC), two widely used anti-oxidants, were employed to evaluate the role of oxidative stress in Japanese encephalitis virus (JEV) induced autophagy, stress responses and replication. DPI and NAC exerted opposite effects on ROS levels in JEV infected mouse neuronal cells (Neuro2a), mouse embryonic fibroblasts (MEFs) and human epithelial cells (HeLa). While NAC effectively quenched ROS, DPI enhanced ROS levels, suggesting that DPI induces oxidative stress in JEV infected cells. DPI treatment of JEV infected Neuro2a cells further blocked autophagy induction and activation of all three arms of the ER stress pathway, and, inhibited virus particle release. Autophagy induction in JEV infection has been previously shown to be linked to the activation of XBP1 and ATF6 ER stress sensors. Our data suggests that DPI mediated block of autophagy is a result of inhibition of ER stress responses and is not associated with an anti-oxidative effect. Since DPI has a wide inhibitory potential for all Flavin dependent enzymes, it is likely that the signalling pathways for ER stress and autophagy during JEV infection are modulated by DPI sensitive enzymes.
Sujet(s)
Virus de l'encéphalite japonaise (espèce)/effets des médicaments et des substances chimiques , Composés onium/pharmacologie , Acétylcystéine/pharmacologie , Animaux , Antioxydants/pharmacologie , Autophagie/effets des médicaments et des substances chimiques , Cellules cultivées , Virus de l'encéphalite japonaise (espèce)/pathogénicité , Virus de l'encéphalite japonaise (espèce)/physiologie , Stress du réticulum endoplasmique/effets des médicaments et des substances chimiques , Cellules HeLa , Humains , Souris , Stress oxydatif/effets des médicaments et des substances chimiques , Suidae , Réplication virale/effets des médicaments et des substances chimiquesRÉSUMÉ
Stringent regulation of antiviral signaling and cellular autophagy is critical for the host response to virus infection. However, little is known how these cellular processes are regulated in the absence of type I interferon signaling. Here, we show that ATF3 is induced following Japanese encephalitis virus (JEV) infection, and regulates cellular antiviral and autophagy pathways in the absence of type I interferons in mouse neuronal cells. We have identified new targets of ATF3 and show that it binds to the promoter regions of Stat1, Irf9, Isg15 and Atg5 thereby inhibiting cellular antiviral signaling and autophagy. Consistent with these observations, ATF3-depleted cells showed enhanced antiviral responses and induction of robust autophagy. Furthermore, we show that JEV replication was significantly reduced in ATF3-depleted cells. Our findings identify ATF3 as a negative regulator of antiviral signaling and cellular autophagy in mammalian cells, and demonstrate its important role in JEV life cycle.
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Facteur de transcription ATF-3/métabolisme , Autophagie , Virus de l'encéphalite japonaise (espèce) , Encéphalite japonaise/métabolisme , Encéphalite japonaise/virologie , Interféron de type I/métabolisme , Transduction du signal , Animaux , Lignée cellulaire , Encéphalite japonaise/génétique , Régulation de l'expression des gènes , Interactions hôte-pathogène/génétique , Humains , Sous-unité gamma du complexe ISGF3/génétique , Sous-unité gamma du complexe ISGF3/métabolisme , Souris , Régions promotrices (génétique) , Liaison aux protéines , Facteurs de transcription STAT/génétique , Facteurs de transcription STAT/métabolisme , Suidae , Réplication viraleRÉSUMÉ
Algal carbon-concentrating mechanisms can be used to sequester CO2 from the atmosphere, and the resulting biomass can produce various value-added products. Mechanisms for carbon concentration in algae are complex and sometimes inefficient. We need to understand how algae successfully overcome these challenges while capturing CO2 from their nearby environment.
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Polluants atmosphériques/métabolisme , Dioxyde de carbone/métabolisme , Cyanobactéries/croissance et développement , Microalgues/croissance et développementRÉSUMÉ
Endoplasmic reticulum (ER) stress and autophagy are key cellular responses to RNA virus infection. Recent studies have shown that Japanese encephalitis virus (JEV)-induced autophagy negatively influences virus replication in mouse neuronal cells and embryonic fibroblasts, and delays virus-induced cell death. Here, we evaluated the role of ER stress pathways in inducing autophagy during JEV infection. We observed that JEV infection of neuronal cells led to activation of all three sensors of ER stress mediated by eIF2α/PERK, IRE1/XBP1 and ATF6. The kinetics of autophagy induction as monitored by levels of SQSTM1 and LC3-II paralleled activation of ER stress. Inhibition of the eIF2α/PERK pathway by siRNA-mediated depletion of proteins and by the PERK inhibitor had no effect on autophagy and JEV replication. However, depletion of XBP1 and ATF6, alone or in combination, prevented autophagy induction and significantly enhanced JEV-induced cell death. JEV-infected cells depleted of XBP1 or ATF6 showed reduced transcription of ER chaperones, ERAD components and autophagy genes, resulting in reduced protein levels of the crucial autophagy effectors ATG3 and BECLIN-1. Conversely, pharmacological induction of ER stress in JEV-infected cells further enhanced autophagy and reduced virus titres. Our study thus demonstrates that a crucial link exists between the ER stress pathways and autophagy in virus-infected cells, and that these processes are highly regulated during virus infection.