Search Results (240)

The increasing environmental release of nano-titanium dioxide (nTiO₂) due to its widespread industrial application raises concerns about its potential effects on aquatic ecosystems, particularly marine organisms. Fertilization, a critical reproductive process for broadcast-spawning bivalves, is highly sensitive to environmental pollutants. In the present investigation, we explored the effects of nTiO₂ at environmentally relevant concentrations on oocyte quality and the fertilization process in the economically important marine bivalve Tegillarca granosa. nTiO₂ exposure significantly reduced fertilization success and sperm–egg fusion efficiency, while markedly increasing polyspermy incidence. Mechanistically, nTiO₂ triggered oxidative stress in oocytes, elevating ROS and MDA levels and causing structural damage to the oocyte membrane. Moreover, nTiO₂ exposure disrupted cellular energy metabolism by inhibiting PK and PFK activities, depleting ATP content, and reducing MMP. Additionally, nTiO₂ exposure impaired Ca²⁺ homeostasis by suppressing Ca²⁺-ATPase activity, which reduced intracellular Ca²⁺ levels. These cellular disruptions collectively compromised the cortical reaction by inhibiting cortical granule exocytosis and microfilament migration. Our findings suggest that nTiO₂-induced oxidative stress, coupled with an imbalance in energy and Ca²⁺ homeostasis, impairs the cortical reaction and fertilization capacity in T. granosa. This study provides valuable insights into the mechanistic pathway underlying the reproductive toxicity of nTiO₂ in marine invertebrates, offering a basis for evaluating the ecological risks associated with the presence of nanomaterials in marine environments. Full article

In skeletal muscles fibers, cellular respiration, excitation–contraction (EC) coupling (the mechanism that translates action potentials in Ca²⁺ release), and store-operated Ca²⁺ entry (SOCE, a mechanism that allows recovery of external Ca²⁺ during fatigue) take place in organelles specifically dedicated to each function: (a) aerobic ATP production in mitochondria; (b) EC coupling in intracellular junctions formed by association between transverse tubules (TTs) and sarcoplasmic reticulum (SR) named triads; (c) SOCE in Ca²⁺ entry units (CEUs), SR-TT junctions that are in continuity with membranes of triads, but that contain a different molecular machinery (see Graphical Abstract). In the past 20 years, we have studied skeletal muscle fibers by collecting biopsies from humans and isolating muscles from animal models (mouse, rat, rabbit) under different conditions of muscle inactivity (sedentary aging, denervation, immobilization by casting) and after exercise, either after voluntary training in humans (running, biking, etc.) or in mice kept in wheel cages or after running protocols on a treadmill. In all these studies, we have assessed the ultrastructure of the mitochondrial network and of the sarcotubular system (i.e., SR plus TTs) by electron microscopy (EM) and then collected functional data correlating (i) the changes occurring with aging and inactivity with a loss-of-function, and (ii) the structural improvement/rescue after exercise with a gain-of-function. The picture that emerged from this long journey points to the importance of the internal architecture of muscle fibers for their capability to function properly. Indeed, we discovered how the intracellular organization of the mitochondrial network and of the membrane systems involved in controlling intracellular calcium concentration (i[Ca²⁺]) is finely controlled and remodeled by inactivity and exercise. In this manuscript, we give an integrated picture of changes caused by inactivity and exercise and how they may affect muscle function. Full article

Inorganic polyphosphate is highly conserved, critical, yet poorly understood polymer that regulates diverse cellular functions in mammals. Its importance is well established in coagulation, inflammation, mitochondrial function, and stress responses, though the molecular mechanisms for these effects remain only partly understood. Fundamental questions also persist regarding its physiological concentration, chain-length distributions, and the mechanisms that regulate its behavior in specific cellular compartments. Progress is limited by the absence of a known mammalian polyphosphate-synthesizing enzyme. Despite this, recent studies have broadened the scope of polyphosphate biology, suggesting roles in protein phase separation, ATP-independent chaperone activity, metabolic regulation, and intracellular signaling. Polyphosphate modulates the mitochondrial permeability transition pore through calcium-dependent regulation and activates factor XII in coagulation. Findings have also introduced potential connections between polyphosphate and processes such as neurodegeneration, cancer, and tissue regeneration. Despite this expanding landscape, many biological effects remain difficult to interpret due to incomplete mapping of protein targets and longstanding technical limitations in detecting and quantifying polyP. This review integrates molecular protein-interaction mechanisms with compartment-specific functions and disease physiology, providing a clearer mechanistic framework while identifying key conceptual and methodological gaps and outlining priorities for advancing polyphosphate research in mammalian systems. Full article

In this study, a strain of green microalga adapted to the extreme environmental conditions of the Tibetan Plateau was isolated from the Lalu Wetland. The isolate was identified and tentatively designated as Micractinium sp. LL-1. Following the inoculation of strain LL-1 into tannery wastewater, the ammonia nitrogen concentration was rapidly reduced, achieving a removal efficiency of 98.7%. The maximum accumulated biomass reached 1641.68 mg/L and 1461.28 mg/L. Integrated transcriptomic and label-free quantitative proteomic approaches were employed to systematically investigate the molecular response mechanisms of LL-1 under tannery wastewater stress. Transcriptomic analysis revealed that differentially expressed genes were enriched in pathways related to cell proliferation, morphogenesis, intracellular transport, protein synthesis, photosynthesis, and redox processes. Proteomic analysis indicated that LL-1 enhances cellular and enzymatic activities, strengthens regulatory capacity, modulates key metabolic pathways, and upregulates stress-responsive proteins. Under tannery wastewater stress, LL-1 exhibits dynamic adaptation involving signal perception and metabolic reconfiguration through the coordinated regulation of multiple pathways. Specifically, ribosomal translation and nucleic acid binding regulate biosynthetic capacity; the redistribution of energy metabolism boosts photosynthetic carbon fixation and ATP generation; and membrane transport coupled with antioxidant mechanisms mitigates stress-induced damage. Collectively, this study provides theoretical insights into microalgal adaptation to complex wastewater environments and offers potential targets for strain improvement and wastewater valorization. Full article

Bacterial carbonic anhydrases (CAs) are essential for intracellular pH regulation, bicarbonate homeostasis, and energy metabolism, making them attractive antimicrobial targets. Here, building on evidence that acetazolamide (AZA) delivered via hyaluronic acid–palmitate (HA-PA) nanocarriers impairs Escherichia coli growth and its glucose uptake, we investigated the physiological roles of β- and γ-class CAs using sulphonamide inhibitors with distinct selectivity encapsulated in HA-PA nanomicelles to ensure intracellular delivery. AZA, a potent dual β/γ-CA inhibitor, ethoxzolamide (EZA), a selective β-CA inhibitor, and hydrochlorothiazide (HCT), a weaker inhibitor of both classes, were tested for effects on bacterial physiology. The nanoparticles reduced growth in a dose- and class-dependent manner, with AZA exerting the strongest activity, EZA intermediate inhibition, and HCT only modest effects at higher concentrations. Early metabolic responses assessed via intracellular ATP after three hours of exposure revealed an unexpected and reproducible ATP increase for all inhibitors relative to untreated cells, suggesting reduced ATP consumption in bicarbonate-dependent pathways. These findings provide indirect yet compelling evidence that β- and γ-class CAs influence bacterial energy homeostasis and support the rationale for CA inhibition as an antimicrobial strategy, while highlighting HA-PA carriers as effective systems for delivering CA inhibitors intracellularly and enhancing their functional activity in bacterial cells. Full article

Anthonoic acids A–C (1–3), the first representatives of sulfated and N-(2-hydroxyethyl)-substituted lipidic α-amino acids, were isolated along with their plausible precursor, anthamino acid A (4), from the marine sponge Antho ridgwayi. The structures of these compounds were determined using the analysis of 1D and 2D NMR and HR ESI mass spectra. A structural feature of 1–4, compared to all previously known lipidic amino acids, is the presence of a sulfate group near the end opposite the amino acid terminus. At a concentration of 1 µM, anthonoic acids A–C (1–3) effectively protected H9c2 and SH-SY5Y cells in biotests, which modeled hypoxia induced by the addition of CoCl₂ to the medium and damage caused by ischemia/reperfusion. These natural products act via the Nrf2-mediated pathway by reducing intracellular ROS levels, accompanied by the upregulation of SOD activity, which is controlled by the Nrf2 transcriptional factor. Anthonoic acids A–C (1–3) do not activate the transcriptional activity of NF-κB but inhibit ATP-induced cell damage and calcium influx, indicating the involvement of P2X7 receptors in the cytoprotective effect of anthonoic acids A–C. Full article

Background: The reintroduction of colistin has led to the rapid emergence of colistin-resistant strains, significantly diminishing its therapeutic efficacy. This presents a need for effective adjuvants to restore colistin efficacy. Approach: We screened the colistin adjuvants through a high-throughput method and then evaluated their synergistic effects and underlying mechanisms. Results: We identified β,β-dimethylacrylalkannin (β,β-Dim), a naphthoquinone compound derived from Lithospermum erythrorhizon, as a potent colistin adjuvant (fractional inhibitory concentration index (FICI) < 0.5). β,β-Dim enhanced colistin activity against 4 of 6 susceptible strains and all 18 colistin-resistant strains carrying either plasmid-borne mcr genes (mcr-1, mcr-3, mcr-8, and mcr-9) or chromosomal two-component system (TCS) mutations (pmrA/B, phoP, and mgrB). These strains included Klebsiella pneumoniae, Escherichia coli, Salmonella Typhimurium, Pseudomonas aeruginosa, and Acinetobacter baumannii. The combination reduced the minimum inhibitory concentrations (MICs) of colistin by 4–1024-fold (from 512 to ≤2 µg/mL). Mechanistically, colistin-mediated outer membrane permeabilization facilitates β,β-Dim entry. Once internalized, β,β-Dim interacts with cytoplasmic membrane phospholipids and disrupts membrane biofunction. Further analysis showed that LPS transport and efflux pump activity were impaired, leading to LPS accumulation in the cytoplasmic membrane and increased intracellular colistin content. These processes elevated reactive oxygen species (ROS) production and markedly reduced ATP levels. In a murine infection model, β,β-Dim (2 mg/kg) combined with colistin (0.2 mg/kg) markedly increased survival from 20% (colistin alone) to 80%. Conclusions: These findings highlight that β,β-Dim combined with colistin is a promising therapeutic strategy for infections caused by colistin-resistant pathogens. Full article

Platelets are anucleate cells whose dysregulation contributes to thrombocytopenia during sepsis. Thrombocytopenia is an early complication of Gram-negative infection, in which lipopolysaccharide (LPS) serves as a principal mediator; however, its precise contribution remains unclear. In this study, LPS, at concentration 10 µg/mL, did not induce human platelet aggregation but significantly potentiated low-dose collagen (0.5 μg/mL)-induced aggregation, ATP release, intracellular calcium levels ([Ca²⁺]i) and P-selectin expression. Scanning electron microscopy revealed that either collagen or LPS activated filopodia elongation in human platelets, whereas LPS combined with collagen further activated the phenotype of platelet activation (lamellipodia formation). Beyond these activation responses, LPS also increased TLR4 expression and triggered hallmark apoptotic events, including mitochondrial depolarization, Bax expression, caspase-8 and caspase-3 activation, and phosphatidylserine exposure, concomitant with downregulation of Bcl-2. Moreover, LPS-induced apoptotic platelets displayed ultrastructural changes, characterized by membrane blebbing and filopodia loss. Thus, these findings present the first evidence that LPS enhances platelet aggregation in association with apoptosis through the TLR4–Bax/Bcl-2–mitochondrial dysfunction–caspase-8/3 activation signaling pathway, providing mechanistic insight into sepsis-associated thrombocytopenia. Full article

The concentration of intracellular adenosine triphosphate (ATP) is one of the most important characteristics of the metabolic state of the cells of microorganisms and their viability. This indicator, monitored by bioluminescent ATP-metry, and accumulation of the suspension biomass in the medium were used to assess the effect of particles of different synthetic microplastics (MPs) (non-biodegradable and biodegradable) on the cells of yeast, filamentous fungi, bacteria and phototrophic microorganisms (microalgae and cyanobacteria) co-exposed with polymer samples in different environments and concentrations. It was found that the effect of MPs on microorganisms depends on the concentration of MPs (1–5 g/L), as well as on the initial concentration of cells (10⁴ or 10⁷ cells/mL) in the exposure medium with polymers. It was shown that the lack of a sufficient number of nutrition sources in the medium with MPs is not fatal for the cells. The study of the effect of MPs on the photobacteria Photobacterium phosphoreum, widely used as a bioindicator for assessing the ecotoxicity of various environments, demonstrated a correlation between the residual bioluminescence of these cells and the level of their intracellular ATP in media with biodegradable polycaprolactone and polylactide, which had an inhibitory effect on these cells. Marine representatives of phototrophic microorganisms showed the greatest sensitivity to the presence of MPs, which was confirmed by both a decrease in the level of intracellular ATP and the concentration of their biomass. Among the eight microorganisms studied, bacteria of the genus Pseudomonas turned out to be not only the most tolerant to the presence of the seven MP samples used in the work, but also actively growing in their presence. Full article

Statins are the first-line therapy for managing elevated cholesterol levels that represent a risk of acute cardiovascular events. However, the use of statins is associated with several side effects, likely due to the depletion of Coenzyme Q₁₀ (CoQ₁₀), a key component of the mitochondrial electron transport chain and a membrane antioxidant. In our study, we present evidence of the cytotoxic effects of Atorvastatin on human dermal fibroblasts in terms of oxidative stress and mitochondrial impairment. Interestingly, CoQ₁₀ supplementation in statin-treated cells significantly reduced ROS levels and restored mitochondrial oxygen consumption rate and the intracellular ATP/ADP ratio. Moreover, our data suggest that the mechanism for Atorvastatin off-target effects at high concentrations involves the inhibition of respiratory complexes I and III, leading to reverse electron transport and ROS production by Complex I. These findings highlight the potential benefits of CoQ₁₀ supplementation in mitigating statin-induced cytotoxicity and propose a mechanistic basis for the adverse effects associated with Atorvastatin therapy. Full article

Tuberculosis (TB) persists as a formidable global health threat, especially with the rising incidence of multidrug-resistant strains. This study aimed to evaluate the in vitro activity of contezolid, a novel oxazolidinone antibiotic, against Mycobacterium tuberculosis (Mtb) and assess potential cross-resistance with linezolid. Thirty-one Mtb clinical isolates (5 susceptible, 8 multidrug-resistant [MDR], 18 pre-extensively drug-resistant [pre-XDR]) were tested. Minimum inhibitory concentrations (MICs) of contezolid and linezolid were determined, along with mutation resistance frequencies. Intracellular replication inhibition in macrophages and whole-genome sequencing of resistant colonies were assessed. Cytotoxicity was evaluated via luciferase-coupled ATP assay. The MIC50 and MIC90 values of contezolid were comparable to those of linezolid. Contezolid induced higher mutation frequencies in 7 isolates. At 12 mg/L, both drugs similarly inhibited intracellular Mtb replication. Whole-genome sequencing revealed that the mce3R gene was linked to contezolid resistance, with no cross-resistance observed between two drugs. No significant cytotoxicity was observed in contezolid-treated mouse peritoneal macrophages (p > 0.05). Contezolid exhibits anti-Mtb activity, with mce3R potentially associated with resistance. No cross-resistance with linezolid was found. Full article

This study aimed to investigate whether intracellular complement 3 (C3) activation regulates ATP production in yak rumen epithelial cells under inflammatory conditions and its potential mechanism. An in vitro inflammation model was established by stimulating yak rumen epithelial cells with lipopolysaccharide (LPS). Then, protease inhibitors targeting C3 activation enzymes were added. Additionally, to explore the downstream signaling pathway, exogenous C3a and the C3a receptor (C3aR) inhibitor C3aRY were applied to the inflammation model. After treatment with different concentrations of LPS, the gene expression levels and concentrations of pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6 were significantly up-regulated (p < 0.05), while a significant reduction in cellular ATP levels was observed (p < 0.05), along with a significant reduction in mitochondrial membrane potential (p < 0.05). After treating the inflammation model with different protease inhibitors, the ATP content and gene expression of the ATP synthase subunit ATP5A were significantly increased (p < 0.05). Exogenous addition of the C3aR inhibitor C3aRY in the inflammation model exhibited a significant increase in ATP content and ATP5A gene expression (p < 0.05) when compared to the inflammation model. These results demonstrated that intracellular C3 activation inhibited ATP production in yak rumen epithelial cells under inflammatory conditions, likely through C3a–C3aR signaling and the cAMP/PKA pathway. Full article

Background/Objectives: Glucagon-like peptide-1 (GLP-1) is an endogenous hormone with receptors widely expressed across multiple organs. GLP-1 receptor agonists (GLP-1RAs), primarily used for diabetes management, have demonstrated anti-inflammatory and antioxidant properties beyond glucose regulation. This study explores the protective effect of semaglutide, a GLP-1RA, in reducing oxidative stress and promoting wound healing in human dermal fibroblasts. Additionally, it assesses whether semaglutide offers the direct protection of retinal endothelial cells under oxidative stress. Methods: Human dermal fibroblasts and retinal endothelial cells were treated with semaglutide at concentrations ranging from 0 to 45 pg/mL for 24 h under oxidative stress induced by hydrogen peroxide (H₂O₂). Cell viability and ATP levels were measured via MTT and ATP assays. Apoptosis was evaluated using propidium iodide staining. Intracellular reactive oxygen species (ROS) and mitochondrial superoxide were assessed through confocal microscopy with specific fluorescent probes. Wound healing was tested using scratch assays, with closure monitored over time and quantified with ImageJ (version 1.51). Gene expression levels of antioxidants, extracellular matrix components, inflammatory cytokines, and MMPs (MMP3, MMP9) were determined via real-time PCR. Results: Semaglutide significantly improved cell viability and ATP production under oxidative stress (p < 0.001), while reducing apoptosis and intracellular ROS levels. It notably accelerated fibroblast wound closure, achieving near-complete restoration. Gene analysis revealed increased expression of antioxidant and ECM-related genes, along with decreased pro-inflammatory cytokines and MMPs, indicating reduced inflammation and enhanced tissue remodeling. Conclusions: Semaglutide offers robust antioxidative and cytoprotective effects in dermal fibroblasts and retinal endothelial cells, promoting wound healing. These findings highlight its therapeutic potential for diabetic foot ulcers and diabetic retinopathy, supporting further in vivo investigation. Full article

Background: Gold nanoparticles (AuNPs) have several beneficial properties that make them effective as intracellular drug carriers, and their potential for various diagnostic and therapeutic applications is gaining recognition. Depending on their size and shape, AuNPs can cross the central nervous system (CNS) through the blood–brain barrier (BBB). In the CNS, they can exert a variety of influences on neuronal and glial cells, which can be both supportive—promoting cell health and function—and cytotoxic, potentially leading to cellular damage. The hypothalamus (HT) is the first region where nanoparticles (NPs) interact, as this neuroendocrine center is particularly sensitive to factors in the systemic circulation due to its function and location. This area is affected by systemic factors, including pro-opiomelanocortin (POMC) neurons, which regulate metabolic function and maintain homeostasis. The activity of mitochondria within these cells influences their response to both external factors and the presence of AuNPs, thereby facilitating a complex interplay between nanoparticle interactions and cellular metabolism in this vital brain region. Aims: This study investigates how AuNPs, at different concentrations and exposure times under in vitro conditions, affect the mitochondrial activity of POMC neurons, aiming to provide a comprehensive understanding of the mechanisms in the HT. Methods: The study investigates the effect of varying gold nanoparticle concentrations on the mitochondrial activity of POMC neurons over treatment periods of 1, 15, 24, and 48 h. Mitochondrial activity was measured using a Seahorse XFp Analyzer to provide high-resolution insights. Additionally, mitochondrial functionality was assessed through the detection of reactive oxygen species (ROS) and cell viability. Results: The findings indicated that the effects of gold nanoparticles on mitochondrial activity depend significantly on their concentration and exposure time. Specifically, exposure leads to an increase in early response systems, the citric acid cycle, and proton efflux, ultimately resulting in the inhibition of mitochondrial function and ATP production in POMC cells. This disruption may affect hypothalamic regulation and energy metabolism. Full article

The administration of isolated mitochondria is a promising strategy for protecting cells from oxidative damage. This study aimed to identify mitochondrial characteristics that contribute to stronger protective effects. We compared two types of mitochondria isolated from C6 cells with similar ATP-producing capacity but differing in outer membrane integrity. To evaluate their stability in extracellular conditions, we examined their behavior in serum. Both types underwent mitochondrial permeability transition to a similar extent; however, under intracellular-like conditions after serum incubation, mitochondria with intact membranes retained more polarized mitochondria. Notably, mitochondria with intact outer membranes were internalized more efficiently than those with damaged membranes. In H9c2 cells, both types of mitochondria similarly increased intracellular ATP levels 1 h after administration under all tested conditions. When co-administered with H₂O₂, both suppressed oxidative damage to a comparable degree, as indicated by similar H₂O₂-scavenging activity in solution, comparable intracellular ROS levels, and equivalent preservation of electron transport chain activity. However, at higher H₂O₂ concentrations, cells treated with mitochondria possessing intact outer membranes exhibited greater survival 24 h after co-administration. Furthermore, when mitochondria were added after H₂O₂-induced damage and their removal, intact mitochondria conferred superior cell survival compared to damaged ones. These findings suggest that while both mitochondrial types exert comparable antioxidant effects, outer membrane integrity prior to administration plays a critical role in enhancing cell survival under conditions of oxidative stress. Full article