Search Results (463)

Background: There is growing interest in the potential role of manganese (Mn) in the development of Alzheimer’s Disease and related dementias (ADRD). Methods: In this nested pilot study of a ferroalloy worker cohort, we investigated the impact of chronic occupational Mn exposure on cognitive function through β-amyloid (Aβ) deposition and multi-omics profiling. We evaluated six male Mn-exposed workers (median age 63, exposure duration 31 years) and five historical controls (median age: 60 years), all of whom had undergone brain PET scans. Exposed individuals showed significantly higher Aβ deposition in exposed individuals (p < 0.05). The average annual cumulative respirable Mn was 329.23 ± 516.39 µg/m³ (geometric mean 118.59), and plasma Mn levels were significantly elevated in the exposed group (0.704 ± 0.2 ng/mL) compared to controls (0.397 ± 0.18 in controls). Results: LC-MS/MS-based pathway analyses revealed disruptions in olfactory signaling, mitochondrial fatty acid β-oxidation, biogenic amine synthesis, transmembrane transport, and choline metabolism. Simoa analysis showed notable alterations in ADRD-related plasma biomarkers. Protein microarray revealed significant differences (p < 0.05) in antibodies targeting neuronal and autoimmune proteins, including Aβ (25–35), GFAP, serotonin, NOVA1, and Siglec-1/CD169. Conclusion: These findings suggest Mn exposure is associated with neurodegenerative biomarker alterations and disrupted biological pathways relevant to cognitive decline. Full article

Cold environments challenge the structural and functional integrity of membrane proteins, requiring specialized adaptations to maintain activity under low thermal energy. Here, we investigate the molecular basis of cold tolerance in the peptide transporter PepT1 from the Antarctic icefish (Chionodraco hamatus, ChPepT1) using molecular dynamics simulations, binding free energy calculations (MM/GBSA), and dynamic network analysis. We compare ChPepT1 to its human ortholog (hPepT1), a non-cold-adapted variant, to reveal key features enabling psychrophilic function. Our simulations show that ChPepT1 displays enhanced global flexibility, particularly in domains adjacent to the substrate-binding site and the C-terminal domain (CTD). While hPepT1 loses substrate binding affinity as temperature increases, ChPepT1 maintains stable peptide interactions across a broad thermal range. This thermodynamic buffering results from temperature-sensitive rearrangement of hydrogen bond networks and more dynamic lipid interactions. Importantly, we identify a temperature-responsive segment (TRS, residues 660–670) within the proximal CTD that undergoes an α-helix to coil transition, modulating long-range coupling with transmembrane helices. Dynamic cross-correlation analyses further suggest that ChPepT1, unlike hPepT1, reorganizes its interdomain communication in response to temperature shifts. Our findings suggest that cold tolerance in ChPepT1 arises from a combination of structural flexibility, resilient substrate binding, and temperature-sensitive interdomain dynamics. These results provide new mechanistic insight into thermal adaptation in membrane transporters and offer a framework for engineering proteins with enhanced functionality in extreme environments. Full article

The fungal kingdom, with an estimated five million species, has undergone extensive diversification over the past billion years and now occupies a wide array of ecological niches from terrestrial to aquatic ecosystems. To thrive in such diverse environments, fungi must exhibit finely tuned physiological and morphological responses orchestrated by conserved molecular pathways. Increasing evidence suggests that aquaporins (AQPs) play a key role in mediating these adaptive responses, particularly under varying abiotic and biotic stress conditions. However, despite notable advances in recent decades, the precise functional roles of AQPs within the fungal kingdom remains largely unresolved in the field of cell biology. AQPs are transmembrane proteins belonging to the major intrinsic proteins (MIPs) superfamily, which is characterized by remarkable sequence and structural diversity. Beyond their established function in facilitating water transport, MIPs mediated the bidirectional diffusion of a range of small inorganic and organic solutes, ions, and gases across cellular membranes. In fungi, MIPs are classified into three main subfamilies: orthodox (i.e., classical) AQPs, aquaglyceroporins (AQGP), and X-intrinsic proteins (XIPs). This review provides a concise summary of the fundamental structural and functional characteristics of fungal aquaporins, including their structure, classification, and known physiological roles. While the majority of the current literature has focused on the aquaporin and aquaglyceroporin subfamilies, this review also aims to offer a comprehensive and original overview of the relatively understudied X-intrinsic protein subfamily, highlighting its potential implication in fungal biology. Full article

Bestrophinopathies are a group of inherited retinal diseases caused by mutations in the BEST1 gene. The protein encoded by this gene, bestorphin-1 (hBest1), is a calcium-dependent transmembrane channel localized on the basolateral membrane of retinal pigment epithelial (RPE) cells. We have already demonstrated the surface behavior and organization of recombinant hBest1 and its interactions with membrane lipids such as 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM) and cholesterol (Chol) in models of biological membranes, which affect the hBest1 structure–function relationship. The main aim of our current investigation is to integrate pure hBest1 protein into lipid bilayer nanostructures. We synthesized and characterized various hBest1-containing nanostructures based on 1,2-Dipalmitoylphosphatidylcholine (DPPC), SM, glycerol monooleate (GMO) and Chol in different ratios and determined their cytotoxicity and incorporation into cell membranes and/or cells by immunofluorescence staining. Our results show that these newly designed nanoparticles are not cytotoxic and that their incorporation into MDCK II cell membranes (used as a model system) may provide a mechanism that could be applied to RPE cells expressing mutated hBest1 in order to restore their ion transport functions, affected by mutated and malfunctioning hBest1 molecules. Full article

Aquaporins in rice (Oryza sativa L.) represent a pivotal class of transmembrane channel proteins that mediate the bidirectional transport of water and small solutes, which have critical functions in cellular osmoregulation and ion homeostasis maintenance. Their evolutionary diversity and functional plasticity constitute fundamental mechanisms underlying the adaptive responses to diversified environmental challenges. This review systematically summarizes rice AQPs’ evolutionary origins, structural characteristics, and spatiotemporal expression patterns under both physiological and stress conditions, highlighting the high conservation of their key functional domains across evolution and their environment-driven functional diversification. The molecular mechanisms governing AQPs in water utilization, nutrient uptake, and stress responses are unraveled. Furthermore, the potential of precision gene editing and multi-omics integration is discussed to decipher the intricate relationships between AQP evolutionary history, environmental adaptability, and functional specialization, thereby providing a theoretical basis for advancing crop stress resistance and high-quality breeding. Full article

Introduction: The interface between T cells and the tumor microenvironment, termed the ‘immunological synapse’, consists of multiple checkpoint protein pairs co-expressed on both sides of the synapse. mir-16, a microRNA from a widely known tumor-suppressor family of miRNAs, was previously shown by us to be downregulated in melanoma. As other miRNAs from this family have been shown to directly target checkpoint proteins, here we investigated whether miR-16 influences the expression patterns of checkpoint proteins in melanoma. Methods: Single-cell gene expression data from the melanoma microenvironment were retrieved from a public database. Melanoma cell lines were established from metastatic lesions and transiently transfected with an hsa-miR-16-5p-mimic RNA or a mir-16-expressing plasmid. The mRNA expression profiles were analyzed using an Affymetrix microarray. Direct targets of miR-16 were identified by luciferase reporter assays. Protein levels were assessed by Western blotting. Results: Bioinformatic analysis revealed that the expression levels of eight checkpoint mRNAs, known to be present on the melanoma side of the immunological synapse, were highly correlated. Four of these mRNAs contained putative binding sites for the miR-15/16 family. miR-16 expression was significantly reduced in melanoma cells, compared to normal melanocytes. Luciferase reporter assays demonstrated that miR-16 directly targets the 3′ untranslated regions (3′UTRs) of CD40, CD80. The mRNAs downregulated following miR-16 overexpression were highly enriched for genes involved in autophagy, vesicle-mediated transport, and the regulation of protein membrane localization. Among these, VTI1B and SMPD1 were confirmed to be direct targets of miR-16. Transient overexpression of miR-16 resulted in a significant reduction in SMPD1 and VTI1B levels in melanoma cell lines. Conclusions: Our findings suggest that miR-16 potentially modulates melanoma tumorigenesis, metastasis and immunogenicity by altering the composition of checkpoint proteins at the immunological synapse and by regulating cellular pathways associated with intracellular trafficking and transmembrane protein presentation. Full article

Maltose and maltotriose are the most abundant sugars in brewing wort, and their transport represent a critical bottleneck in the fermentation process. This transport relies on specific transmembrane proteins; however, many yeast strains exhibit inefficient uptake of these sugars, particularly maltotriose. Addressing this limitation requires a comprehensive understanding of the factors influencing the transport of maltose and maltotriose. This review provides a detailed synthesis of the key characteristics and functions of the maltose and maltotriose transmembrane transporters identified in brewer’s Saccharomyces yeasts. Critical amino acid residues involved in transporter activity are also highlighted, and the impact of specific polymorphisms and sequence variations on sugar preference and uptake efficiency is examined. Furthermore, a thorough discussion of the most important reported residues is presented, underscoring the need to closely examine their amino acid composition to better understand transporter mechanisms, optimize their performance, and enhance fermentation outcomes. Full article

Signal peptides (SPs) are short amino acid sequences located at the N-terminus of nascent proteins and are widely present across various life forms. They play crucial roles in protein synthesis, transmembrane transport, and intracellular signal transduction. With the rapid advancement of bioinformatics, studies have revealed that the functions of SPs are far more complex than previously understood. In recombinant protein expression systems, the rational design and optimization of SPs are essential for enhancing the expression efficiency and secretion level of exogenous proteins. Meanwhile, the application value of SPs in vaccine development has attracted increasing attention. This review summarizes the structural characteristics, functional mechanisms, and applications of SPs in recombinant protein production and SP-based vaccines. It also discusses their biological roles, the significance of engineering optimization strategies, and the current challenges, aiming to provide theoretical support and practical guidance for improving recombinant protein yield and advancing SP-based vaccine development. Full article

Serratia plymuthica, isolated from the midgut of Aedes aegypti, displays remarkable resilience to hemin, a toxic hemoglobin byproduct generated during blood digestion. This study explores its proteomic adaptations under oxidative stress induced by 5 mM hemin, mimicking midgut conditions. Growth assays demonstrated that S. plymuthica tolerated hemin concentrations ranging from 5 µM to 1 mM, reaching the stationary phase within approximately 10 h. Colonies exhibited morphological changes—darkened peripheries and translucent halos—suggesting heme accumulation and detoxification. Label-free quantitative proteomics identified 436 proteins, among which 28 were significantly upregulated—including universal stress proteins (USPs), ABC transporters, and flavodoxin—while 54 were downregulated, including superoxide dismutase and several ribosomal proteins. Upregulated proteins were associated with antioxidant defense, heme transport, and redox regulation, whereas downregulated proteins suggested metabolic reprogramming to conserve energy under stress. Functional enrichment analysis revealed significant alterations in transmembrane transport, oxidative stress response, and central metabolism. These findings suggest that S. plymuthica contributes to redox homeostasis in the mosquito gut by mitigating reactive oxygen species (ROS) and detoxifying excess heme, supporting its role as a beneficial symbiont. The observed stress tolerance mechanisms may influence mosquito physiology and vector competence, offering novel insights into mosquito–microbiota interactions and potential microbiota-based strategies for vector control. Full article

Zygotic genome activation (ZGA) marks the critical transition from reliance on maternal transcripts to the initiation of embryonic transcription early in development. Despite extensive characterization in model species, the regulatory framework of ZGA in sheep remains poorly defined. Here, we applied single-cell RNA sequencing (Smart-seq2) to in vivo- and in vitro-derived sheep embryos at the 8-, 16-, and 32-cell stages. Differential expression analysis revealed 114, 1628, and 1465 genes altered in the 8- vs. 16-, 16- vs. 32-, and 8- vs. 32-cell transitions, respectively, with the core pluripotency factors SOX2, NANOG, POU5F1, and KLF4 upregulated during major ZGA. To uncover coordinated regulatory modules, we constructed a weighted gene co-expression network using WGCNA, identifying the MEred module as most tightly correlated with developmental progression (r = 0.48, p = 8.6 × 10⁻¹⁴). The integration of MERed genes into the STRING v11 protein–protein interaction network furnished a high-confidence scaffold for community detection. Louvain partitioning delineated two discrete communities: Community 0 was enriched in ER–Golgi vesicle-mediated transport, transmembrane transport, and cytoskeletal dynamics, suggesting roles in membrane protein processing, secretion, and early signaling; Community 1 was enriched in G2/M cell-cycle transition and RNA splicing/processing, indicating a coordinated network for accurate post-ZGA cell division and transcript maturation. Together, these integrated analyses reveal a modular regulatory architecture underlying sheep ZGA and provide a framework for dissecting early embryonic development in this species. Full article

Ark shells are a group of bivalves that exhibit extraordinary adaptability to the dual environmental pressures of low oxygen and osmotic imbalance. These challenges are particularly pronounced in intertidal zones, where organisms are subjected to rapid and drastic changes in their surroundings. This research investigated the molecular mechanisms that underpin their survival and adaptive strategies, with particular focused on sodium–potassium ATPase (NKA), a pivotal enzyme responsible for maintaining cellular ion transmembrane gradients and ensuring cellular homeostasis under stress conditions. By utilizing genome assemblies and transcriptomics datasets from multiple ark shell species, we successfully identified two distinct NKA-α subunits and two NKA-β subunits, which are essential components of the NKA complex. Moreover, the discovery of a conserved NKA-interacting protein (NKAIN) highlights the complexity and evolutionary significance of the NKA-NKAIN system in ark shells. Phylogenetic analysis revealed a high degree of conservation in the NKA-α and NKA-β subunits across ark shells, suggesting strong selective pressures to preserve their functionality. However, the marked divergence observed between the two NKA-β subunits suggests that they may serve distinct roles in ion transport, potentially specialized for specific environmental conditions or stress responses. Comparative transcriptomic analysis further revealed the regulatory roles of NKA and NKAIN in the adaptive responses to hypoxia and osmotic stress, showing that these genes are dynamically modulated at the transcriptional level in response to environmental challenges. These findings provide a molecular foundation for understanding the osmotic adaptation mechanisms in ark shells and offer novel insights into their ability to thrive in mudflat habitats. This comprehensive exploration of the NKA-NKAIN system not only enhances our understanding of the resilience of ark shells but also provides valuable insights into the molecular and physiological strategies employed by bivalves in intertidal environments. Full article

The interaction among the various Ca²⁺ transporters complicates the assessment of isolated systems in an intact cell. This article proposes the functionally isolated SR model (FISRM), a hybrid (experimental and mathematical) approach to study Ca²⁺ cycling between the cytosol and the sarcoplasmic reticulum (SR), the main source of Ca²⁺ for contraction in mammalian cardiomyocytes. In FISRM, the main transmembrane Ca²⁺ transport pathways are eliminated by using a Na⁺, Ca²⁺-free extracellular medium, and SR Ca²⁺ release is elicited by a train of brief caffeine pulses. Two compounds that exert opposite effects on the SR Ca²⁺ uptake were characterized by this approach in isolated rat ventricular cardiomyocytes. The experimental FISRM was simulated with a simple mathematical model of Ca²⁺ fluxes across the SR membrane, based on a previous model adapted to the present conditions. To a fair extent, the theoretical model could reproduce the experimental results, and confirm the main assumption of the experimental model: that the only relevant Ca²⁺ fluxes occur across the SR membrane. Thus, the FISRM seems to be a valuable framework to investigate the SR Ca²⁺ transport in intact cardiomyocytes under physiological and pathophysiological conditions, and to test therapeutic approaches targeting SR proteins. Full article

Aquaporins (AQPs) are a family of transmembrane water channel proteins facilitating the transport of water and, in some cases, small solutes such as glycerol, lactate, and urea. In the central nervous system (CNS), several aquaporins play crucial roles in maintaining water homeostasis, modulating cerebrospinal fluid (CSF) circulation, regulating energy metabolism, and facilitating neuroprotection under pathological conditions. Among them, AQP2, AQP4, AQP9, and AQP11 have been implicated in traumatic and non-traumatic brain injuries. The most abundant aquaporin (AQP) in the brain, AQP4, is essential for fluid regulation, facilitating water transport across the blood–brain barrier and glymphatic clearance. AQP2 is primarily known for its function in the kidneys, but it is also expressed in brain regions related to vasopressin signaling and CSF dynamics. AQP9 acts as a channel for glycerol and lactate, thus playing a role in metabolic adaptation during brain injury. AQP11, an intracellular aquaporin, is involved in oxidative stress responses and cellular homeostasis, with emerging evidence suggesting its role in neuroprotection. Aquaporins play a dual role in brain injury; while they help maintain homeostasis, their dysregulation can exacerbate cerebral edema, metabolic dysfunction, and inflammation. In traumatic brain injury (TBI), aquaporins regulate the formation and resolution of cerebral edema. In non-traumatic brain injuries, including ischemic stroke, aneurysmal subarachnoid hemorrhage (aSAH), and intracerebral hemorrhage (ICH), aquaporins influence fluid balance, energy metabolism, and oxidative stress responses. Understanding the specific roles of AQP2, AQP4, AQP9, and AQP11 in these brain injuries may lead to new therapeutic strategies to mitigate secondary damage and improve neurological outcomes. This review explores the function of the above aquaporins in both traumatic and non-traumatic brain injuries, highlighting their potential and limitations as therapeutic targets for neuroprotection and recovery. Full article

Tumor cell heterogeneity, e.g., in stroma-rich pancreatic ductal adenocarcinoma (PDAC), includes a differential metabolism of lactate. While being secreted as waste product by most cancer cells characterized by the glycolytic Warburg metabolism, it is utilized by a subset of highly malignant cancer cells running the reverse Warburg metabolism. Key drivers of lactate transport are the carrier proteins SLC16A1 (import/export) and SLC16A3 (export). Expression and function of both carriers are controlled by the chaperone Basigin (BSG), which itself is functionally controlled by the transmembrane protease serine 11B (TMPRSS11B). In this study we explored the impact of TMPRSS11B on the phenotype of PDAC cells under reverse Warburg conditions. Amongst a panel of PDAC cell lines, Panc1 and BxPc3 cells were identified to express TMPRSS11B at a high level, whilst other cell lines such as T3M4 did not. ShRNA-mediated TMPRSS11B knock-down in Panc1 and BxPc3 cells enhanced lactate import through SLC16A1, as shown by GFP/iLACCO1 lactate uptake assay, whereas TMPRSS1B overexpression in T3M4 dampened SLC16A1-driven lactate uptake. Moreover, knock-down and overexpression of TMPRSS11B differentially impacted proliferation and chemoresistance under reverse Warburg conditions in Panc1 or BxPc3 and T3M4 cells, respectively, as well as their stemness properties indicated by altered colony formation rates and expression of the stem cell markers Nanog, Sox2, KLF4 and Oct4. These effects of TMPRSS11B depended on both SLC16A1 and BSG as shown by gene silencing. Immunohistochemical analysis revealed a reciprocal expression of TMPRSS11B and BSG together with SLC16A1 in some areas of tumor tissues from PDAC patients. Those regions exhibiting low or no TMPRSS11B expression but concomitant high expression of SLC16A1 and BSG revealed greater amounts of KLF4. In contrast, other tumor areas exhibiting high expression of TMPRSS11B together with BSG and SLC16A1 were largely negative for KLF4 expression. Thus, the differential expression of TMPRSS11B adds to metabolic heterogeneity in PDAC and its absence supports the reverse Warburg metabolism in PDAC cells by the enhancement of BSG-supported lactate uptake through SLC16A1 and subsequent phenotype alterations towards greater stemness. Full article

Background: Exosomes have recently attracted significant attention for their potential in drug delivery. Plant-derived exosomes, in particular, may serve as direct anticancer agents due to their unique characteristics, including immunogenicity, biocompatibility, safety, cell-free nature, and nanoscale structure. Methods: This study characterizes Persea americana (avocado)-derived exosomes, exploring their anticancer properties, proteomic profile, and therapeutic potential. Results: Isolated exosomes exhibited a diameter of 99.58 ± 5.09 nm (non-loaded) and 151.2 ± 6.36 nm (doxorubicin (DOX)-loaded), with zeta potentials of −17 mV and −28 mV, respectively. Proteomic analysis identified 47 proteins, including conserved exosome markers (GAPDH, tubulin) and stress-response proteins (defensin, endochitinase). Functional enrichment revealed roles in photosynthesis, glycolysis, ATP synthesis, and transmembrane transport, supported by protein–protein interaction networks highlighting energy metabolism and cellular trafficking. DOX encapsulation efficiency was 18%, with sustained release (44.4% at 24 h). In vitro assays demonstrated reduced viability in breast cancer (MCF-7, T47D, 4T1) and endothelial (C166) cells, enhanced synergistically by DOX (Av+DOX). Gene expression analysis revealed cell-specific modulation: Av+DOX upregulated TP53 and STAT in T47D but suppressed both in 4T1/C166, suggesting context-dependent mechanisms. Conclusions: These findings underscore avocado exosomes as promising nanovehicles for drug delivery, combining biocompatibility, metabolic functionality, and tunable cytotoxicity. Their plant-derived origin offers a scalable, low-cost alternative to mammalian exosomes, with potential applications in oncology and targeted therapy. Further optimization of loading efficiency and in vivo validation are warranted to advance translational prospects. Full article