Search Results (497)

Mucins are highly glycosylated proteins that form the structural basis of mucus and represent a key component of innate immunity at mucosal surfaces, particularly in the respiratory tract. Beyond their mechanical barrier function, mucins actively participate in pathogen trapping, regulation of mucociliary clearance, modulation of inflammatory responses, and maintenance of epithelial homeostasis. Dysregulation of mucin synthesis, composition, or transport contributes to mucus hypersecretion, impaired airway clearance, and chronic inflammation in respiratory diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis. This review summarizes current insights into mucin biology, including their biosynthesis, structure, classification, and regulation, with emphasis on the gel-forming mucins MUC5AC and MUC5B. The role of mucins in mechanical protection, host–pathogen interactions, control of inflammation, and coordination of innate immune responses is reviewed. Attention is given to the interplay between mucins, immune cells, and microbial communities in maintaining airway barrier integrity. The article further examines mucoactive therapeutic strategies aimed at restoring mucus barrier function. Expectorants, mucolytics, mucoregulators, and mucokinetic agents are reviewed with respect to their mechanisms of action and clinical relevance. Established drugs, including N-acetylcysteine, carbocysteine, dornase alfa, ambroxol, and hypertonic solutions, are considered alongside emerging molecular targets such as NF-κB-dependent regulation of mucin expression, calcium-activated chloride channels, MARCKS-mediated mucin exocytosis, purinergic signaling pathways, and NO/cGMP signaling. Non-pharmacological approaches, including airway clearance techniques and respiratory rehabilitation, are covered concisely. Conclusions: Overall, this review highlights mucins as dynamic regulators of innate immunity and underscores the need for mechanism-based, personalized mucoactive therapies to improve outcomes in chronic inflammatory airway diseases. Full article

The common carp (Cyprinus carpio) kidney uniquely integrates excretory nephrons, renal hematopoietic tissue, and hormonally active thyroid follicles, positioning it as a candidate “multipurpose biomarker organ” for pollutants like perfluorooctanoic acid (PFOA), a prototype long-chain PFAS and persistent organic pollutant exhibiting nephrotoxic, immunotoxic, and thyroid-disrupting effects. Building on prior histological, ultrastructural, and morphometric analyses from carp exposed to waterborne PFOA (0, 200 ng L⁻¹, 2 mg L⁻¹ for 56 days), a hierarchical multipurpose index comprising nephrotoxic, immunotoxic, and thyrotoxic subindices was developed from z-scored light-, electron-microscopy, and morphometric features, enabling cross-scale integration; proximal tubule vesiculations and effete rodlet cells (RCs) were newly quantified from archival electron micrographs. The subindices captured PFOA-induced glomerular hyperfiltration with proximal protein reabsorption and collecting duct RCs recruitment (nephrotoxic); hematopoietic tissue RCs recruitment, clustering, and exocytosis (immunotoxic); and increased thyroid follicle abundance/vesiculation, cross-sectional area, and perimeter (thyrotoxic). Quantification of previously only qualitatively assessed features provided statistical validation, while radar plot integration rendered results more intuitively evident—particularly highlighting the non-monotonic thyroid response—condensing organ-level complexity into a coherent framework supporting carp kidney as a translational One Health model for multi-endpoint waterborne pollutant assessment. Full article

Background/Objectives: Type 2 diabetes mellitus (T2DM) is characterized by chronic hyperglycemia and insulin resistance, leading to progressive metabolic dysfunction. Flavonoids, such as astragalin, have reported antidiabetic potential; however, their direct effects on pancreatic β-cell ionic mechanisms and insulin secretion remain unclear. This study aimed to investigate the effects of astragalin on glucose uptake, insulin secretion, and membrane ionic currents in pancreatic β-cell lines. Methods: Murine MIN6 and rat INS-1 pancreatic β-cells were used as experimental models. Following astragalin treatment, glucose uptake was quantified by bioluminescence, and insulin secretion was measured by ELISA. Ionic currents were analyzed using the whole-cell patch-clamp technique. Selective pharmacological blockers targeting ATP-sensitive K⁺ channels (KATP), voltage-dependent K⁺ channels (K_v), and L-type voltage-dependent Ca²⁺ channels were applied to elucidate the underlying mechanisms. Results: Astragalin increased glucose uptake in a time-dependent manner, reaching a plateau between 3 and 5 h. Insulin secretion was significantly enhanced after 1 h of exposure to 100 µM astragalin. Patch-clamp recordings demonstrated that astragalin reduced potassium channel currents in pancreatic β-cells. Pharmacological modulation confirmed the involvement of KATP, K_v, and L-type Ca²⁺ channels. Verapamil attenuated the insulinotropic effect, supporting the role of calcium influx in astragalin-induced insulin exocytosis. Conclusions: Astragalin enhances glucose uptake and stimulates insulin secretion in pancreatic β-cells through modulation of potassium and calcium channels, promoting calcium-dependent exocytosis. These findings support its potential as a candidate for antidiabetic therapeutic strategies. Full article

Multiple sclerosis (MS) is a highly disabling chronic autoimmune disease of the central nervous system with neuroinflammatory and neurodegenerative alterations found in the white and grey matter of the brain. The pathogenesis of MS is complex and not fully understood. Mitochondrial dysfunctions are suspected to play an important role. The visual system is often affected in MS. Optic neuritis is a frequent symptom, but also the retina itself, including retinal synapses appear compromised in MS independent from demyelination of the optic nerve. A previous study demonstrated synapse-specific alterations of mitochondria in photoreceptor synapses in the Experimental Autoimmune Encephalomyelitis (EAE) mouse model of MS at day 9 after injection, an early time point in pre-clinical EAE. In the present study, we analysed even earlier stages of pre-clinical EAE for possible alterations of synaptic mitochondria. For this purpose, we performed qualitative and quantitative immunolabelling analyses of the mitochondrial cristae organising protein MIC60 at retinal synapses and functional analyses by measuring synaptic mitochondrial membrane potential (during rest and depolarisation-induced exocytosis) and visually guided behaviour (optometry analyses). At day 3 after injection, morphological and functional data were indistinguishable between MOG/CFA-injected EAE mice and CFA-injected control mice. But already on day 5 after injection, we observed a decreased expression of the mitochondrial MIC60 protein at synaptic mitochondria, a decreased synaptic mitochondrial membrane potential at rest, an enhanced drop of mitochondrial membrane potential during stimulated exocytosis and a decreased visual performance of the respective EAE mice. These data argue that synaptic pathology in the EAE retina begins as early as day 5 after injection. Our data propose that dysfunctions of mitochondria play an important role already at the very early stages of synaptic pathology in EAE. Full article

Exocytosis is a fundamental biological process in all eukaryotes involving the vesicular transport of cellular cargo to the plasma membrane or extracellular space. However, in walled organisms such as plants, fungi, and certain archaea, the rigid cell wall presents a unique barrier to vesicular secretion. The dense, structured matrix of the mature cell wall restricts the passage of macromolecules and vesicles, raising the fundamental question of how vesicle secretion operates in this constrained environment. In the present study, we integrate transmission electron microscopy (TEM), cryo-electron tomography (cryo-ET), and serial section electron tomography (SS-ET) to investigate the structural mechanisms underlying cell wall-related exocytosis. We demonstrate that secretory vesicles do not undergo fusion with the plasma membrane in cell wall-related vesicle secretion in Arabidopsis thaliana (A. thaliana) and Saccharomyces cerevisiae (S. cerevisiae). Furthermore, in the floral nectary of A. thaliana, we identify the details of vesicles inside the multivesicular body (MVB)-like structure in cell wall. Collectively, these results reveal distinct vesicle secretion pathways adapted to the presence of a cell wall, expanding our understanding of how secretory vesicles traverse and deliver cargo beyond the plasma membrane in walled eukaryotic cells. Full article

Reproductive dysfunction in captive-bred Senegalese sole (Solea senegalensis) limits aquaculture production consolidation, particularly due to reduced fertility and poor sperm quality in F1 males. To elucidate the molecular mechanisms underlying this problem, a quantitative proteomic analysis was conducted using LC–MS/MS on gonadal tissues from wild and F1 males and females. A total of 2221 proteins were identified, of which 1797 were retained after quality filtering. Comparative analyses revealed clear segregation by origin (F1 [cultivated] and wild) and sex (male and female), and 86 proteins were differentially expressed between F1 and wild males. Functional enrichment showed significant downregulation of key reproductive processes in F1 males, including sperm–egg recognition, binding of sperm to zona pellucida, and acrosome reaction, suggesting impaired gamete interaction and fertilization ability. Conversely, F1 males displayed metabolic and proteolytic pathway enrichment, which is indicative of compensatory energy demands. Protein–protein interaction network analysis identified a reproductive subnetwork dominated by zona pellucida sperm-binding proteins, which exhibited reduced connectivity in F1 males. These results demonstrate a coordinated suppression of molecular components essential for sperm–egg communication and acrosomal exocytosis, providing proteomic evidence for the systemic deregulation of the reproductive machinery in F1 fish. This study identifies potential protein biomarkers linked to reproductive performance, offering molecular targets to improve broodstock management and fertilization success in S. senegalensis aquaculture. Full article

Class I myosins form an abundant group of single-headed motor proteins that interact with actin and membrane phospholipids and are employed in a variety of cell processes like cell shape remodeling, motility and invasion, exocytosis, and endocytosis. The large number of class members and their uneven distribution in human cells and tissues complicate their study. Furthermore, this hinders the assessment of their biomarker potential and mechanistic role in oncogenesis and other diseases. Despite the emerging data on their mutations and altered abundance in a number of tumors and other diseases, most studies examine class I myosins individually or in groups of several proteins. Thus, the question of their redundancy and possible functional substitution is ignored. In this work, we simultaneously assess all eight human MYO1 genes on cell lines of different origins by RNA-seq re-analysis. We also report a qPCR system for human myosin I screening and test it on a set of 35 continuous cell lines widely used in biomedicine and fundamental research. These data clarify the restricted expression patterns of MYO1 genes in various human cell types and allow to assess the pattern specific of haematopoietic cell lines. Full article

Background: Poly(lactic-co-glycolic) acid (PLGA) nanoparticles were found to be actively exocytosed from cells in a previous study in our lab. The exocytosis process can be modulated to increase the retention of nanoparticles within the cells so that the therapeutic efficacy of any drug encapsulated within the nanoparticles is increased. So, we wanted to know which membrane proteins were involved in the exocytosis process of the nanoparticles. The roles of VAMP3 and VAMP7, two crucial membrane proteins associated mainly with constitutive and regulated secretion, respectively, in cells, were studied in the context of exocytosis of PLGA nanoparticles. Materials and Methods: The siRNA-mediated knockdown of VAMP3 and VAMP7 genes was performed in the LN229 cancer cell line, and the intracellular accumulation of PLGA nanoparticles was studied by fluorescence microscopy. Results: There was no significant difference in the intracellular accumulation of the PLGA nanoparticles after siRNA-mediated knockdown of VAMP3 or VAMP7. Conclusion: This study shows that VAMP3 and VAMP7, which serve as important membrane proteins associated with the conventional constitutive and regulated secretion of different molecules in cells, are most likely not involved in the exocytosis/secretion of PLGA nanoparticles. So, the pathway of intracellular trafficking of PLGA nanoparticles needs to be deciphered, as it appears to be a non-conventional one. Full article

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

Serotonin (5-HT) performs a wide range of neuromodulatory actions in the nervous system, including the regulation of the neurons that release it, by activation of several types of autoreceptors that modulate their electrical activity, as well as its own release. 5-HT neurons release serotonin in different manners from different subcellular structures, including the presynaptic terminals, the somatodendritic region and the axons. The different releasing structures of the same neurons have different types of autoreceptors, which exert differential auto-regulatory effects. Here we critically review the evidence of serotonergic autoregulation, both in mammals and in invertebrates, with particular emphasis on studies of serotonergic Retzius neurons of the leech, which have been a model for detailed studies of serotonin secretion from different neuronal structures. In these neurons serotonin produces different and even opposite effects on different releasing structures, such as the presynaptic terminals and the soma, through activation of different types of autoreceptors, thus increasing the specialization of the mechanisms that regulate exocytosis from each site. The differential autoregulation of serotonin release from different structures enables a single neuron to exert a variety of different functions in the nervous system. Full article

A growing body of work has linked the dysregulation of transmembrane (TMEM) proteins to the proliferation, metastasis, drug resistance, and tumor microenvironment remodeling of lung cancer, the leading global cause of cancer mortality. Renamed members such as STING1 (stimulator of interferon response cGAMP interactor 1, TMEM173), ANO1 (anoctamin-1, TMEM16A), ORAI1 (ORAI calcium release-activated calcium modulator 1, TMEM142A), ORAI3 (TMEM142C), and NDC1 (NDC1 transmembrane nucleoporin, TMEM48) are among the most extensively studied ones. Mechanisms of TMEM dysregulation in lung cancer span the modulation of Ca²⁺ influx, lysosomal exocytosis, ferroptosis, Wnt and β-catenin signaling, and immune cell infiltration and immune checkpoint rewiring, among others. Epigenetic silencing and targetable fusions (i.e., TMEM106B-ROS1 and TMEM87A-RASGRF1) create DNA-level vulnerabilities, while miRNA sponges offer RNA-level druggability. A subset of studies revealed context-specific expression (endothelial, B cell, and hypoxic EV) that can be exploited to remodel the tumor microenvironment. One study specifically focused on how isoform-specific expression and localization of TMEM88 determine its functional impact on tumor progression. Yet for most TMEMs, only pre-clinical or early-phase data exist, with many supported by a single study lacking independent validation. This review brings together scattered evidence on TMEM proteins in lung cancer, with the aim of guiding future work on their possible use as biomarkers or therapeutic targets. Full article

Severe crusting dermatosis affecting the mucocutaneous junctions, pressure points, and trunk of dogs fed low-quality dry food was first reported in the United States in the 1980s. Since then, only a few cases have been documented. Twenty-two adult dogs owned by private individuals were evaluated. All dogs exhibited thick crusts forming plaques and marked scaling on the face—particularly around the lips, nasal bridge, and eyelids—as well as on the paw pads, dorsal digits, abdomen, and dorsum. Pruritus ranged from moderate to severe, and all dogs showed varying degrees of lethargy and reduced activity. Each dog was fed a low-quality commercial diet. A presumptive diagnosis of dermatosis associated with poor-quality food was made. Skin biopsies from nine dogs revealed similar histopathologic changes, characterized by epidermal hyperplasia, severe parakeratotic hyperkeratosis with spongiosis, and exocytosis of lymphocytes and neutrophils. The skin lesions resolved within 15–30 days after switching to a high-quality diet. This case series highlights that dermatosis associated with low-quality food should remain in the differential diagnosis for dogs presenting with symmetric crusted and scaly lesions on the face, mucocutaneous junctions, and paws, particularly when nutritional deficiencies are suspected. Full article

Neuronal synapses are the functional units of communication in the central nervous system. This review describes the molecular mechanisms regulating synaptic transmission, plasticity, and circuit refinement. At the presynaptic active zone, scaffolding proteins including bassoon, piccolo, RIMs, and munc13 organize vesicle priming and the localization of voltage-gated calcium channels. Neurotransmitter release is mediated by the SNARE complex, comprising syntaxin-1, SNAP25, and synaptobrevin, and triggered by the calcium sensor synaptotagmin-1. Following exocytosis, synaptic vesicles are recovered through clathrin-mediated, ultrafast, bulk, or kiss-and-run endocytic pathways. Postsynaptically, the postsynaptic density (PSD) serves as a protein hub where scaffolds such as PSD-95, shank, homer, and gephyrin anchor excitatory (AMPA, NMDA) and inhibitory (GABA-A, Glycine) receptors are observed. Synaptic strength is modified during long-term potentiation (LTP) and depression (LTD) through signaling cascades involving kinases like CaMKII, PKA, and PKC, or phosphatases such as PP1 and calcineurin. These pathways regulate receptor trafficking, Arc-mediated endocytosis, and actin-dependent remodeling of dendritic spines. Additionally, synapse formation and elimination are guided by cell adhesion molecules, including neurexins and neuroligins, and by microglial pruning via the complement cascade (C1q, C3) and “don’t eat me” signals like CD47. Molecular diversity is further expanded by alternative splicing and post-translational modifications. A unified model of synaptic homeostasis is required to understand the basis of neuropsychiatric and neurological disorders. Full article

Serotonergic signaling is traditionally conceived as a transient, vesicle-mediated process restricted to the synaptic cleft. Here, we propose an expanded model in which serotonin can also be inserted into the plasma membrane of neurons and glial cells, forming a stable, membrane-associated reservoir that prolongs its availability beyond classical synaptic timescales. In this framework, the synapse emerges not as a simple neurotransmitter–receptor interface but as a dynamic, multiscale medium where membrane order, hydration, and quantum-level processes jointly govern information flow. Two temporal “tunnels” appear to regulate serotonin bioavailability: its aggregation in synaptic vesicles during exocytosis, and its cholesterol-dependent insertion into neuronal and glial membranes at the tripartite synapse. Lipid raft microdomains enriched in cholesterol and gangliosides thus act as active regulators of a continuum between transient and constitutive serotonin signaling. This extended serotonergic persistence prompts a reconsideration of current pharmacological models and the action of antidepressants such as fluoxetine, which not only inhibits the serotonin transporter (SERT) but also accumulates in lipid rafts, perturbs raft organization, and alters serotonin–cholesterol equilibria, contributing to SERT-independent effects. Grounded in the recently established fundamental parameters of biological systems, this model invites a broader, quantum-informed rethinking of synaptic transmission. Full article

Synapses, abundant in the brain, are structures needed for life. Our Introduction, based on the forms of such structures published few decades ago, helped in developing recent concepts of health and diseases. Growing axons govern their growth by cell-to-cell communication, axon guidance, and synapse orientations. The assembly of synapses requires the organization and function of pre-synaptic and post-synaptic neuronal terminals with a liquid–liquid phase, governed by Ca²⁺ responses of thin astrocyte domains. Upon synapse stimulation, the clefts expand up to several folds while pre- and post-synaptic thickness remains unchanged. In additional responses, neurons co-operate with astrocytes and extracellular vesicles (EVs), the latter dependent on extracellular and intracellular spaces. Astrocyte and microglia cells and/or EV secretions induce neurons by various effects including traveling changes. Pre-synaptic responses are defined as canonical if based on neurotransmitter release; non-canonical if they are without release and are discharged by EVs, not neurotransmitters. Health and diseases depend on other general properties, such as those defined molecularly. Among neurodegenerative diseases, attention is specified by various properties of Alzheimer’s and other diagnoses. Critical identifications can be due to astrocyte and microglia cells or multiple effects induced by EVs. At present, the complexity of therapies, although of limited success, is developing innovative initiatives. Full article