Search Results (435)

Human leukocyte antigen class I (HLA-I) molecules present intracellular peptides on the cell surface to enable CD8+ T cells to effectively control viral infections. Many viruses disrupt this antigen presentation pathway to evade immune detection. In this study, we demonstrate that SARS-CoV-2 Nsp1 impairs both the constitutive and interferon-γ (IFN-γ)-induced upregulation of HLA-I. Moreover, Nsp1 also blocks IFN-γ-induced expression of HLA-II. We found that, contrary to previously published work, the early SARS-CoV-2 B 1.1.7 Alpha variant lacking the accessory protein ORF8 retained full capacity to downregulate HLA-I, comparable to an ORF8-expressing wild-type isolate. While ectopic overexpression of ORF8 could reduce HLA-I surface levels, this effect was only observed at high expression levels. In contrast, moderate expression of the viral protein Nsp1 was sufficient to potently suppress both basal and IFN-γ-induced HLA-I, as well as HLA-II expression. To probe the underlying mechanism, we analyzed HLA-I-associated genes in previously published RNA-sequencing datasets and confirmed that Nsp1 reduces expression of components required for HLA-I biosynthesis and antigen processing. These findings identify Nsp1 as a key factor that impairs antigen presentation pathways, potentially contributing to the ability of SARS-CoV-2 to modulate immune recognition. Full article

The demand for eco-friendly nanomaterial synthesis has increased interest in biological approaches. Yeast-mediated biosynthesis of gold nanoparticles (AuNPs) offers a sustainable alternative with potential biotechnological applications. This study developed a rapid screening method to identify oleaginous yeast strains able to synthesize AuNPs. A collection of 114 oleaginous yeasts from the LIBBA laboratory was screened. UV–Vis spectroscopy at 530–560 nm was used to assess nanoparticle formation, identifying 20 strains that effectively synthesize AuNP. Electron microscopy confirmed the presence of intracellular and extracellular nanoparticles, with variations in size and morphology. This screening and optimization approach effectively identified promising yeast candidates and refined biosynthesis conditions, providing a foundation for industrial-scale nanoparticle production. Full article

Perturbations in the tightly regulated processes of VLDL biosynthesis and secretion can directly impact both liver and cardiovascular health. Patients with metabolic disorders have an increased risk of developing hepatic steatosis, which can lead to cirrhosis. These associated metabolic risks underscore the importance of discerning the role of different cellular proteins involved in VLDL biogenesis, transport, and secretion. Small VCP-Interacting Protein (SVIP) has been identified as a component of VLDL transport vesicles and VLDL secretion. This study evaluates the cellular effects stemming from the CRISPR-Cas9-mediated depletion of SVIP in rat hepatocytes. The SVIP-knockout (KO) cells display an increased VLDL retention with elevated intracellular levels of ApoB100 and neutral lipid staining. RNA sequencing studies reveal an impaired PPARα and Nrf2 signaling in the SVIP KO cells, implying a state of metabolic reprograming, with a shift from fatty acid uptake, synthesis, and oxidation to cells favoring the activation of glucose by impaired glycogen storage and increased glucose release. Additionally, SVIP KO cells exhibit a transcriptional profile indicative of acute phase response (APR) in hepatocytes. Many inflammatory markers and genes associated with APR are upregulated in the SVIP KO hepatocytes. In accordance with an APR-like response, the cells also demonstrate an increase in mRNA expression of genes associated with protein synthesis. Together, our data demonstrate that SVIP is critical in maintaining hepatic lipid homeostasis and metabolic balance by regulating key pathways such as PPARα, Nrf2, and APR. Full article

The environmental burden of conventional plastics has sparked interest in sustainable alternatives such as polyhydroxyalkanoates (PHAs). However, despite ample research in bioprocess development and the use of inexpensive waste streams, production costs remain a barrier to widespread commercialization. Complementary to this, genetic engineering offers another avenue for improved productivity. Cupriavidus necator stands out as a model host for PHA production due to its substrate flexibility, high intracellular polymer accumulation, and tractability to genetic modification. This review delves into metabolic engineering strategies that have been developed to enhance the production of poly(3-hydroxybutyrate) (PHB) and related copolymers in C. necator. Strategies include the optimization of central carbon flux, redox and cofactor balancing, adaptation to oxygen-limiting conditions, and fine-tuning of granule-associated protein expression and the regulatory network. This is followed by outlining engineered pathways improving the synthesis of PHB copolymers, PHBV, PHBHHx, and other emerging variants, emphasizing genetic modifications enabling biosynthesis based on unrelated single-carbon sources. Among these, enzyme engineering strategies and the establishment of novel artificial pathways are widely discussed. In particular, this review offers a comprehensive overview of promising engineering strategies, serving as a resource for future strain development and positioning C. necator as a valuable microbial chassis for biopolymer production at an industrial scale. Full article

Galectin-3 (Gal-3) is a β-galactoside-binding lectin that mediates diverse signaling events in multiple cell types, including immune cells. It is also a prognostic indicator for multiple clinically important disorders, including cardiovascular disease. Gal-3 binds to cell surface glycans to form lattices that modulate surface receptor signaling and internalization. However, the tissue-specific regulation of Gal-3 surface expression remains poorly understood. Here, we review evidence for the involvement of Gal-3 in cell surface signaling, intranuclear events, and intracellular trafficking. Our focus will be on the O-GlcNAc modification as a regulator of Gal-3 biosynthesis, non-canonical secretion, and recycling. We argue that the nutrient-driven cytoplasmic hexosamine biosynthetic pathway (HBP) and endomembrane transport mechanisms generate unique pools of nucleotide sugars. The differing levels of nucleotide sugars in the cytosol, endoplasmic reticulum (ER), and Golgi apparatus generate differential thresholds for the responsiveness of O-GlcNAc cycling, N- and O-linked glycan synthesis/branching, and glycolipid synthesis. By regulating Gal-3 synthesis and non-canonical secretion, O-GlcNAc cycling may serve as a nexus constraining Gal-3 cell surface expression and lattice formation. This homeostatic feedback mechanism would be critical under conditions where extensive glycan synthesis and branching in the endomembrane system and on the cell surface are maintained by elevated hexosamine synthesis. Thus, O-GlcNAc cycling and Gal-3 synergize to regulate Gal-3 secretion and influence cellular signaling. In humans, Gal-3 serves as an early-stage prognostic indicator for heart disease, kidney disease, viral infection, autoimmune disease, and neurodegenerative disorders. Since O-GlcNAc cycling has also been linked to these pathologic states, exploring the interconnections between O-GlcNAc cycling and Gal-3 expression and synthesis is likely to emerge as an exciting area of research. Full article

The production of β-alanine from fatty acid feedstocks presents a promising synthetic strategy due to its high carbon yield. However, the excessive reducing power generated during fatty acid utilization disrupts cellular redox balance, adversely affecting metabolism and limiting the efficiency and final yield of β-alanine production. To address this challenge, we engineered a co-production system in which excess reducing equivalents generated during fatty acid β-oxidation and β-alanine biosynthesis were consumed by growth-coupled lycopene biosynthesis. The resulting dual-pathway strain, SA01, achieved 44.78 g/L β-alanine and 3.07 g/L lycopene in bioreactor fermentation, representing a 21.45% increase in β-alanine production compared to the β-alanine-producing strain WA01, and a 74.43% increase in lycopene production compared to the lycopene-producing strain LA01. Further optimization in strain SA06, involving cofactor engineering to shift redox flow from NADH to NADPH, enhanced the titers to 52.78 g/L β-alanine and 3.61 g/L lycopene. Metabolite analysis confirmed a decrease in intracellular NADH and FADH₂ levels in SA06, indicating restoration of redox balance during the late fermentation phase. Additional improvements in the fermentation process, including gradual carbon source switching, optimization of the induction strategy, and fine-tuning of conditions during both growth and bioconversion phases, resulted in further increases in product titers, reaching 72 g/L β-alanine and 6.15 g/L lycopene. This study offers valuable insights into the development of microbial co-production systems, highlighting the critical role of dynamic cofactor and redox balance management, as well as process optimization, in improving production efficiency. Full article

Pediococcus pentosaceus, an important lactic acid bacterium in the brewing of Chinese Baijiu (liquor), usually encounters environmental stresses including ethanol and lactic acid, which severely impact cellular growth and metabolism. In this study, a combined physiological and omics analysis was employed to elucidate the response mechanisms of P. pentosaceus under ethanol and lactic acid stress conditions. The results showed that the biomass of cells decreased by about 40% under single-stress conditions and 70% under co-stress conditions. Analysis of the differentially expressed genes revealed that the cells adjusted various cellular processes to cope with environmental stresses, including modifications in cell wall synthesis, membrane function, and energy production pathways. Meanwhile, the increased expression of genes involved in DNA repair system and protein biosynthesis ensured the normal physiological function of cells. Notably, under ethanol stress, P. pentosaceus upregulated genes involved in unsaturated fatty acid biosynthesis, enhancing membrane stability and integrity. Conversely, under lactic acid stress, cells downregulated F-type ATPase, reducing H⁺ influx to maintain intracellular pH homeostasis. The metabolomic analysis revealed DNA damage under co-stress conditions and further validated the transcriptomic results. Our findings elucidate the molecular and physiological strategies of P. pentosaceus under acid and ethanol stress, providing a foundation for optimizing fermentation processes and enhancing microbial resilience in industrial settings. Full article

Helicobacter pylori is a gastric pathogen implicated in peptic ulcer disease and gastric cancer. The increasing prevalence of antibiotic-resistant strains underscores the urgent need for alternative therapeutic strategies. In this study, we investigated the chemical composition and antibacterial activity of an aqueous extract from Caulerpa lentillifera (sea grape), a farm-cultivated edible green seaweed collected from Krabi Province, Thailand. Ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) revealed that the extract was enriched in bioactive nucleosides and phenolic compounds. In vitro assays demonstrated dose-dependent inhibition of H. pylori growth following exposure to sea grape extract. Furthermore, untargeted intracellular metabolomic profiling of H. pylori cells treated with the extract uncovered significant perturbations in central carbon and nitrogen metabolism, including pathways associated with the tricarboxylic acid (TCA) cycle, one-carbon metabolism, and alanine, aspartate, and glutamate metabolism. Pyrimidine biosynthesis was selectively upregulated, indicating a potential stress-induced shift toward nucleotide salvage and DNA repair. Of particular note, succinate levels were markedly reduced despite accumulation of other TCA intermediates, suggesting disruption of electron transport-linked respiration. These findings suggest that bioactive metabolites from C. lentillifera impair essential metabolic processes in H. pylori, highlighting its potential as a natural source of antimicrobial agents targeting bacterial physiology. Full article

Background: Under oxidative stress conditions, the increased levels of reactive oxygen species (ROS) within cells disrupt the intracellular homeostasis. Tartary buckwheat peptides exert their effects by scavenging oxidative free radicals, such as superoxide anion and hydrogen peroxide, thereby reducing oxidative damage within cells. Meanwhile, these peptides safeguard mitochondria by maintaining the mitochondrial membrane potential, decreasing the production of mitochondrial oxygen free radicals, and regulating mitochondrial biogenesis and autophagy to preserve mitochondrial homeostasis. Through these mechanisms, Tartary buckwheat peptides restore the intracellular redox balance, sustain cellular energy metabolism and biosynthesis, and ensure normal cellular physiological functions, which is of great significance for cell survival and adaptation under oxidative stress conditions. Objectives: In this experiment, a classical cellular oxidative stress model was established. Indicators related to antioxidant capacity and mitochondrial membrane potential changes, as well as pathways associated with oxidative stress, were selected for detection. The aim was to elucidate the effects of Tartary buckwheat oligopeptides on the metabolism of cells in response to oxidative stress. Methods: In this study, we established an oxidative damage model of mouse skeletal muscle myoblast (SOL8) cells using hydrogen peroxide (H₂O₂), investigated the pre-protective effects of Tartary buckwheat oligopeptides on H₂O₂-induced oxidative stress damage in SOL8 cells at the cellular level, and explored the possible mechanisms. The CCK-8 method is a colorimetric assay based on WST-8-[2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodiumsalt], which is used to detect cell proliferation and cytotoxicity. Results: The value of CCK-8 showed that, when the cells were exposed to 0.01 mmol/L H₂O₂ for 1 h and 10 mg/mL Tartary buckwheat oligopeptides intervention for 48 h, these were the optimal conditions. Compared with the H₂O₂ group, the intervention group (KB/H₂O₂ group) showed that the production of ROS was significantly reduced (p < 0.001), the malondialdehyde (MDA) content was significantly decreased (p < 0.05), and the activity of catalase (CAT) was significantly increased (p < 0.01); the mitochondrial membrane potential in the KB/H₂O₂ group tended to return to the level of the control group, and they all showed dose-dependent effects. Compared with the H₂O₂ group, the mRNA expression of KEAP1 in the KB/H₂O₂ group decreased, while the mRNA expression of NRF2α, HO-1, nrf1, PGC-1, P62, and PINK increased. Conclusions: Therefore, Tartary buckwheat oligopeptides have a significant pre-protective effect on H₂O₂-induced SOL8 cells, possibly by enhancing the activity of superoxide dismutase, reducing ROS attack, balancing mitochondrial membrane potential, and maintaining intracellular homeostasis. Full article

Objectives: Modern lifestyles factors such as digital overload, aging, and poor sleep hygiene have led to increasing cases of sleep disturbances and inflammation-related disorders. These conditions are often associated with oxidative stress and immune dysregulation. Longan flower extract (LFE), traditionally used in East Asian medicine, has shown potential health benefits but remains scientifically underexplored. This study aims to investigate the chemical composition and bioactive effects of LFE on inflammation, oxidative stress, and melatonin biosynthesis in relevant cellular models. Methods: LFE was prepared using ethanol extraction and characterized for its total polyphenols, flavonoids, oligomeric proanthocyanidins (OPCs), and corilagin content via HPLC. Its anti-inflammatory, antioxidant, and neuroregulatory activities were assessed in LPS-stimulated RAW 264.7 macrophages and BV-2 microglial cells. Key assays included quantification of cytokines (TNF-α, IL-6), detection of nitric oxide (NO) and reactive oxygen species (ROS), and measurement of antioxidant enzyme activities (GPx, SOD). Gene expression of melatonin biosynthesis enzymes was evaluated using quantitative PCR. Results: LFE treatment significantly reduced LPS-induced TNF-α, IL-6, NO, and ROS production in both cell models. It enhanced GPx and SOD activity and increased intracellular glutathione levels. Moreover, LFE upregulated the expression of TPH1, DDC, AANAT, and ASMT, genes involved in melatonin biosynthesis, and promoted serotonin secretion. Conclusions: These findings suggest that LFE holds significant potential as a natural therapeutic supplement, particularly for alleviating sleep disturbances, reducing oxidative stress, and modulating inflammatory responses associated with modern lifestyle-related health conditions. Full article

As emerging contaminants increasingly detected in aquatic and terrestrial ecosystems, environmental estrogens (EEs) pose significant ecological risks to marine ecosystems, particularly affecting photosynthetic microorganisms occupying fundamental roles in marine food webs. This review summarizes the current knowledge on the toxicological effects of EEs in marine microalgae through a systematic analysis of dose-dependent physiological, biochemical, and molecular responses. Experimental evidence reveals a biphasic response pattern characterized by growth promotion and photosynthetic enhancement in microalgae under low-concentration EE exposure (0.1–10 μg/L), while marked inhibition of both growth and photosynthetic activity was observed at elevated EE concentrations (>50 μg/L). Notably, sustained EE exposure induces metabolic reprogramming, manifested through reduced protein and polysaccharide biosynthesis concurrent with accelerated lipid accumulation. Cellular stress responses include significant ultrastructural alterations such as chloroplast membrane disruption, cell wall thickening, and the formation of multicellular aggregates. The study further elucidates the concentration-dependent modulation of toxin metabolism, with sublethal doses stimulating intracellular microcystin synthesis (1.5–2.3-fold increase), while acute exposure triggers toxin release through membrane permeabilization. At molecular levels, transcriptomic analyses identify the up-regulation of heat shock proteins (HSP70/90) and the differential expression of genes governing cell cycle progression (cyclin-D), apoptotic pathways (caspase-3), photosynthetic electron transport (psbA), and oxidative stress responses (SOD, CAT). These findings demonstrate that EEs exert multilevel impacts on microalgal physiology through interference with fundamental metabolic processes, potentially disrupting marine primary productivity and biogeochemical cycles. The identified response mechanisms provide critical insights for environmental risk assessment and establish a conceptual framework for investigating estrogenic pollutant effects in aquatic ecosystems. Full article

Objectives: The aim of this study was to evaluate the impact of a novel antioxidant formulation (RE:PAIR, RP-25) containing CoQ10, alpha-lipoic acid, and Chaga extract on mitochondrial dysfunction and oxidative stress. To explore the activity of the formulation on neuronal cells, we explored cell metabolism and its activity as an antioxidant, using a combination of NMR-based metabolomics and UHPLC-HRMS analytical techniques. Methods: SH-SY5Y neuroblastoma cells were treated with RP-25, and cell viability was assessed via CCK-8 assay. Metabolomic profiles of the treated and untreated cells were analyzed by 1D-NMR, providing insights into both intracellular metabolites (endometabolome) and excreted metabolites (exometabolome). Additionally, a UHPLC-HRMS method was developed for quality control and analysis of the RP-25 formulation. Multivariate statistical approaches, including PLS-DA and volcano plot analyses, were used to identify key metabolic changes. Changes in mitochondrial membrane potential were assessed by means of TMRE assay, while radical oxygen species (ROS) were measured by means of the DCHF assay. Results: RP-25 treatment did not affect cell viability but significantly increased metabolic pathways, including amino acid biosynthesis, oxidative phosphorylation, and glycolysis. Higher levels of ATP, glutamate, tyrosine, and proline were observed in treated cells than in control cells, indicating enhanced cellular energy production, as also proved by the increased stability of the mitochondrial membrane after RP-25 treatment, an index of preserved mitochondrial functions. In support, the formulation RP-25 showed antioxidant activity when cells underwent peroxide oxygen stimulation. This effect was mainly due to the combination of Chaga, CoQ10, and ALA, main components of the RP25 formulation. Moreover, the analysis of enriched pathways highlighted that RP formulation influenced mitochondrial energy and oxidative stress response. Conclusions: RP-25 demonstrated biological activity in that it mitigated mitochondrial dysfunction and oxidative stress in neuronal cells, with potential implications in neuronal diseases associated with dysfunctional mitochondria. Full article

Listeria monocytogenes is a foodborne pathogen frequently exposed to oxidative stress in diverse environmental conditions. Cyclic di-AMP (c-di-AMP) is a second messenger that plays a key role in stress resistance. This study investigates the role of pdeA (degrades c-di-AMP) and how c-di-AMP accumulation affects catalase activity and oxidative stress response and gene expression. Survival and catalase activity assays were conducted under oxidative stress, and c-di-AMP levels were quantified in L. monocytogenes 10403S under aerobic, anaerobic, and L-cysteine-supplemented conditions. ΔpdeA, which accumulates c-di-AMP, exhibited greater sensitivity to oxidative stress (4.6 log reduction for the wild type (WT) vs 7.34 log reduction for ΔpdeA at 10 h) and lower catalase activity than the WT in the early stationary phase. However, in the late stationary phase, while the catalase activity levels of ΔpdeA remained stable (~6.33 cm foam height), it became resistant to oxidative stress (5.85 log reduction). These findings indicate that pdeA contributes to catalase activity in L. monocytogenes. Transcriptomic analysis revealed differential expression of pathways mainly including pentose phosphate pathway, carbon metabolism, O-antigen nucleotide sugar biosynthesis and ABC transporters in ΔpdeA compared to WT. Our transcriptomic data provided promising insights into the molecular mechanisms underlying c-di-AMP regulation, which may enhance stress resistance. Moreover, oxidative stress led to increased intracellular c-di-AMP levels. Under L-cysteine supplementation, catalase activity levels in WT were similar to ΔpdeA (~1.86 cm foam height for both), but the latter showed enhanced oxidative stress resistance and c-di-AMP levels. Anaerobic conditions also elevated c-di-AMP levels in WT and ΔpdeA but resulted in greater oxidative stress sensitivity. Understanding these regulatory mechanisms provides valuable insights into oxidative stress resistance, with potential implications for food safety and pathogen control. Full article

Background/Objectives: The anti-Leishmania potential of Curcuma longa and its derivatives, such as curcuminoids, is well-established, yet their mechanisms of action remain underexplored. This study investigates the inhibitory effects of C. longa extracts and curcumin on Leishmania infantum arginase, a key enzyme in polyamine and trypanothione biosynthesis, and evaluates their antiparasitic activity. Methods: Extracts were prepared via rhizome successive maceration with hexane (HEXCURC), dichloromethane (DCCURC), and ethanol (ETOHCURC) and chemically characterized by a combination of chromatographic and spectrometric methods. The inhibition of recombinant L. infantum arginase (LiARG) was assessed by urea quantification, while molecular docking explored interactions between the main compounds annotated in the extracts and the enzyme’s active site. Biological activity was tested against L. infantum promastigotes, intracellular amastigotes, and mammalian cells. Results: LC-MS and GC-MS revealed curcuminoids and turmerones as main compounds annotated in the extracts. DCCURC, HEXCURC, and curcumin showed the strongest LiARG inhibition (IC₅₀ = 10.04, 14.4, and 17.55 μg/mL, respectively). Docking analysis revealed that curcumin, demethoxycurcumin, and bisdemethoxycurcumin bind near the active site, with binding energies of –3.43, –4.14, and –3.99 kcal/mol, respectively. Curcumin demonstrated superior anti-promastigote activity (IC₅₀ = 15.01 μg/mL) and selectivity (SI = 12.7) compared to the extracts. It also significantly reduced amastigote burden in infected macrophages (IC₅₀ = 13.6 μg/mL). Conclusions: This is the first report demonstrating that C. longa extracts and curcumin inhibit LiARG. These findings support curcumin’s potential as a lead compound for developing multi-target therapies against leishmaniasis, combining enzyme inhibition with direct antiparasitic effects. Full article

In non-ribosomal peptide synthesis of cyanobacteria, promiscuous adenylation domains allow the incorporation of clickable non-natural amino acids into peptide products—namely into microcystins (MCs) or into anabaenopeptins (APs): 4-azidophenylalanine (Phe-Az), N-propargyloxy-carbonyl-L-lysine (Prop-Lys), or O-propargyl-L-tyrosine (Prop-Tyr). Subsequently, chemo-selective labeling is used to visualize the clickable cyanopeptides using Alexa Fluor 488 (A488). In this study, the time-lapse build up or decline of azide- or alkyne-modified MCs or APs was visualized during maximum growth, specifically MC biosynthesis in Microcystis aeruginosa and AP biosynthesis in Planktothrix agardhii. Throughout the time-lapse build up or decline, the A488 signal occurred with heterogeneous intracellular distribution. There was a fast increase or decrease in the A488 signal for either Prop-Tyr or Prop-Lys, while a delayed or unobservable A488 signal for Phe-Az was related to increased cell size as well as a reduction in growth and autofluorescence. The proportion of clickable MC/AP in peptide extracts as recorded by a chemical–analytical technique correlated positively with A488 labeling intensity quantified via laser-scanning confocal microscopy for individual cells or via flow cytometry at the population level. It is concluded that chemical modification of MC/AP can be used to track intracellular dynamics in biosynthesis using both analytical chemistry and high-resolution imaging. Full article