Search Results (807)

B cell activation requires the formation of an immune synapse (IS), where coordinated cytoskeletal remodeling and organelle dynamics enable antigen extraction and presentation. While mitochondria are known to regulate cellular metabolism during activation, their role in IS function remains poorly understood. Here, we investigated how mitochondrial dynamics influence antigen processing and presentation in B cells. We show that B cell receptor (BCR) engagement induces rapid phosphorylation of the mitochondrial fission GTPase Drp1 at Ser616. Treatment with mdivi-1, a compound used to perturb Drp1-associated mitochondrial fission that can also affect mitochondrial complex I activity, altered mitochondrial morphology, reduced mitochondrial activity, and decreased their stable accumulation at the synapse. This was accompanied by increased tubulin acetylation, lysosome retention near the MTOC, and reduced delivery to the synaptic membrane. Accordingly, lysosome fusion, antigen extraction, and presentation to T cells were significantly diminished in mdivi-1-treated B cells. Together, our findings suggest that mdivi-1-sensitive mitochondrial fission and activity are associated with mitochondrial positioning, lysosomal trafficking, and exocytosis at the B cell immune synapse, supporting a model in which mitochondrial dynamics contribute to efficient antigen extraction and presentation. Full article

Background: Early endolysosomal and autophagic defects are among the earliest cellular alterations observed in Alzheimer’s disease (AD). However, the molecular mechanisms linking amyloid precursor protein (APP) metabolism to vesicle trafficking dysfunction remain incompletely understood. The APP-derived fragment C99 has emerged as a potential upstream mediator of intracellular toxicity, but its impact on organelle homeostasis and its modulation by metabolic interventions remain unclear. Methods: To investigate these mechanisms, we expressed human C99 in Drosophila neurons and examined intracellular pathology using ultrastructural analysis, fluorescent reporters of autophagy and mitochondrial turnover, and proteomic interactome mapping. The effects of the ketone body β-hydroxybutyrate (BHB) were evaluated to assess the impact of metabolic intervention. Results: Neuronal C99 expression induced pronounced vesicular abnormalities, impaired autophagic turnover, and disrupted mitochondrial quality control. Transmission electron microscopy revealed extensive accumulation of enlarged vesicular compartments, accompanied by reduced mitochondrial turnover and accumulation of aged mitochondria. BHB treatment restored autophagic cargo clearance, improved mitochondrial turnover, and normalized vesicular ultrastructure. These protective effects required neuronal ketone transport, indicating a neuron-intrinsic metabolic mechanism. Proteomic analysis of the C99-associated interactome revealed that ketone treatment remodels networks enriched for vesicle trafficking and proteostasis pathways. Network prioritization identified the retromer component VPS35 as a candidate regulatory hub. Functional analyses demonstrated that depletion of VPS35 abolished the BHB-dependent restoration of autophagy, mitochondrial turnover, and vesicle morphology. Conclusions: Ketone treatment restores mitochondrial quality control and autophagic homeostasis through a VPS35-dependent mechanism in C99-induced neurodegeneration. These findings provide mechanistic insight into how metabolic interventions may restore intracellular homeostasis in Alzheimer’s disease. Full article

Copper (Cu) contamination in aquatic environments induces oxidative stress and structural damage to crustaceans. This study investigated the protective effects and associated mechanisms of exogenous melatonin (MT) against Cu-induced toxicity in Procambarus clarkii using integrated physiological, histopathological, proteomic, and molecular analyses. MT supplementation enhanced antioxidant defense by elevating SOD, CAT, and T-AOC activities, while reducing MDA accumulation, with peak effects observed at 24 h. MT also restored endogenous melatonin levels and regulated phosphatase activity, thereby maintaining immune and metabolic homeostasis. Histopathology showed reduced hepatopancreatic damage, characterized by reduced epithelial vacuolization and preserved basement membrane integrity. Proteomics suggested that MT modulates a multilayered network associated with detoxification, redox balance, and cellular homeostasis. Pathway enrichment showed that Cu exposure dysregulated proteins involved in mitochondrial biogenesis, ABC transporters, membrane trafficking, and apoptosis. MT administration partially counteracted these alterations and was associated with the regulation of glutathione metabolism, as well as reduced enrichment of lysosome- and apoptosis-related pathways. Quantitative RT-PCR results were consistent with the proteomic data. Overall, MT partially alleviated Cu-induced toxicity and was associated with enhanced antioxidant defense, improved cellular homeostasis, and metabolic regulation. Our study provides new molecular insights and suggests its potential application for mitigating metal toxicity in aquaculture. Full article

Caveolin-1 is a scaffolding protein of caveolae, flask-shaped membrane microdomains involved in diverse cellular processes. Caveolae are primarily localized to the plasma membrane, the trans-Golgi network, and mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs). Most enzymes involved in cholesterol biosynthesis reside in the ER, and although caveolin-1 avidly binds cholesterol, its role in cholesterol trafficking remains unclear. Acyl-coenzyme A:cholesterol acyltransferases (ACAT1 and ACAT2) convert free cholesterol into cholesteryl esters for storage, with ACAT1 serving as the predominant isoenzyme in most cell types. ACAT1 is an ER-resident protein, with a fraction associated with specialized ER subdomains, including the MAM. Here, we report that a subset of caveolin-1 molecules appears to be associated with a fraction of ACAT1 in ER subdomains. Using immunoprecipitation under detergent conditions, immunoadsorption of MAM-enriched membranes under detergent-free conditions, and electron microscopy, we provide evidence consistent with an association between a subset of caveolin-1 molecules and ACAT1. Functionally, in mouse embryonic fibroblasts, we show that genetic ablation of caveolin-1 significantly increases the esterification of low-density lipoprotein-derived cholesterol, suggesting that caveolin-1 may attenuate ACAT1 activity. Collectively, these findings indicate that caveolin-1 may modulate cholesterol esterification and contribute to the regulation of cholesterol distribution among cellular membranes. Full article

Background: Gynecological cancers include collections of cancers with diverse cellular and molecular characteristics that often develop drug resistance, making them treatment-resistant. Biomolecule–drug conjugates (BDCs), especially antibody–drug conjugates (ADCs), have revolutionized the targeted therapy of cancer; however, the creation of these entities has so far been achieved by empirical, resource-intensive design methods. Objective: The aim of this review is to critically analyze how AI can be used for the rational design and optimization of high-affinity BDCs for gynecological cancer treatment. Methods and discussion: Recent advances in machine learning (ML)- and deep learning (DL)-based methods to predict biomolecule-target binding affinity, structural compatibility, linker stability, payload selection, trafficking in the cell, and biomolecule resistance mechanisms are summarized. The review also explores the possibilities for incorporation of structural, chemical, biological, and multi-omics data to enhance specificity, efficacy, and safety of conjugates. Besides antibody-based systems, AI-assisted design approaches with peptides, aptamers, and hybrid biomolecular systems are also included. This review also highlights parameters and experimental/numerical validation restrictions related to data quality, interpretability of models, regulatory aspects, etc. Conclusions: AI-based conjugate engineering is increasingly moving BDC development from a largely ‘trial and error’ approach to a more predictive and data-driven approach. While there are still challenges to be addressed in terms of translations and validations, the potential of AI approaches in the field of precision oncology and the development of more personalized treatment is promising in the context of gynecological cancers. Full article

Pancreatic cancer remains one of the most lethal malignancies worldwide, with pancreatic ductal adenocarcinoma accounting for the vast majority of cases and characterized by extensive desmoplasia, immune exclusion, and resistance to systemic therapies. Increasing evidence implicates lysosomal cathepsins as important regulators of these defining features of pancreatic tumor biology. Cathepsin-dependent proteolysis and lysosome-associated signaling pathways contribute to extracellular matrix remodeling, regulate immune cell trafficking, and influence antigen processing and presentation. Beyond their classical degradative functions, cathepsins participate in stress-adaptive cellular programs linked to autophagy, metabolic regulation, and proteostasis, supporting tumor cell survival under hypoxic, nutrient-limited, and therapy-induced stress conditions. Within the tumor microenvironment, dysregulated cathepsin activity promotes immune evasion by reshaping cytokine networks, impairing effective antigen presentation, and reinforcing physical and functional barriers to cytotoxic T-cell infiltration. Collectively, these mechanisms position the lysosome–cathepsin system as a central regulator of proteolytic remodeling, immune exclusion, and adaptive therapy resistance in pancreatic cancer, highlighting its potential relevance for emerging combinatorial therapeutic strategies. Full article

Ductal carcinoma in situ (DCIS) is a non-invasive precursor to invasive breast cancer. DCIS incidence continues to rise, yet its clinical management remains constrained by the absence of reliable biomarkers that can adequately distinguish indolent lesions from those with high invasive potential, to circumvent over- or under-treatment. Black women with DCIS are significantly more likely to progress to invasive breast cancer, are disproportionately diagnosed with high-grade, hormone receptor-negative lesions, and experience elevated risk of recurrence and mortality relative to White women with DCIS. These disparities persist despite comparable access to screening and treatment, suggesting underlying biological and tissue microenvironmental factors. This review synthesizes emerging evidence implicating early molecular and systemic changes that may be driving the disparity in DCIS progression. We highlight racial distinctions in interconnected pathways involving Wnt/β-catenin signaling, metabolic and nutritional dysregulation, immune microenvironment remodeling, and cellular tolerance of genomic instability. We further discuss how epigenetic alterations, obesity-associated inflammation, and immune dysregulation may arise during the pre-invasive stage that intersect with social and environmental exposures to influence racial differences in lesion fate. We spotlight candidate biomarkers disproportionately associated with aggressive disease in Black women—including KIFC1, a mediator of centrosome clustering and genomic instability tolerance, and ACKR1/DARC, a regulator of chemokine gradients and immune trafficking—as potential drivers of progression-permissive states. This review advances an integrated, equity-informed framework for DCIS progression that links early tumor evolution to coordinated alterations in genomic instability, immune regulation, metabolic signaling, and stress-adaptive pathways. Importantly, we propose that DCIS progression is governed not by isolated molecular alterations but by coordinated programs that enable survival under genomic and immunologic stress. Current clinical risk assays, which primarily capture tumor-intrinsic proliferation and hormone signaling, do not fully resolve these pathways and may therefore incompletely reflect biologically meaningful racial disparities. This synthesis underscores the need for pathway-level, microenvironment-informed, and population-representative approaches to DCIS risk stratification. Advancing such frameworks will be essential for identifying actionable biomarkers, refining early intervention strategies, and ultimately reducing racial disparities in breast cancer outcomes. Full article

Macrophage-derived extracellular vesicles (EVs) have emerged as promising biomimetic platforms for targeted cancer drug delivery due to their biocompatibility, immune-modulatory properties, and tumor-homing capabilities. Among macrophage subtypes, M1-polarized macrophages exhibit potent anti-tumor functions characterized by pro-inflammatory cytokine secretion, improved antigen presentation, and the ability to remodel the tumor microenvironment (TME). Utilizing these properties, M1-polarized macrophage-derived EVs serve as cell-free therapeutic systems capable of delivering bioactive cargo while simultaneously promoting anti-tumor immune responses. However, the clinical application of natural EVs is limited by low yield, heterogeneity, and challenges in large-scale production. Artificial nanovesicles (ANVs) have been developed to address these limitations, offering improved scalability, compositional control, and reproducibility. This review provides an overview of macrophage differentiation and polarization, with a focus on the immunological profile and anti-tumor mechanisms of M1-polarized macrophages. It further discusses current methodologies for EV isolation and ANV generation, along with cargo loading strategies that balance encapsulation efficiency and vesicle stability. In addition, this review also emphasizes their targeting approaches, cellular uptake pathways, and the intracellular trafficking mechanisms that influence delivery efficiency and therapeutic outcomes. Key challenges, including standardization, biological barriers, and functional consistency, are critically evaluated. Emerging strategies that integrate vesicle engineering with personalized medicine underscore the potential of these systems to advance precision oncology. Full article

Background/Objectives: Multiple sclerosis (MS) constitutes a chronic autoimmune, inflammatory, and neurodegenerative disease, with dissemination in space and time, warranting diagnosis. Epstein–Barr virus (EBV) is increasingly recognized as a key contributor to MS pathogenesis. This review summarizes evidence on EBV-related mechanisms of currently approved disease-modifying therapies (DMTs) and emerging EBV-directed therapeutic strategies in MS. Methods: A systematic search of PubMed, Embase, Cochrane, and Web of Science was performed. Original English-language studies addressing EBV-related therapeutic mechanisms or EBV-targeted interventions in MS were included; 23 studies met the inclusion criteria. Results: Current DMTs may influence EBV-related immunity through diverse mechanisms, including modulation of B-cell subsets, altered lymphocyte trafficking, reduction in EBV-specific humoral responses, and restoration of T-cell surveillance. Monoclonal antibody-based therapies, particularly anti-CD20 agents and natalizumab, appear to affect the EBV–B-cell–immune axis through distinct but complementary mechanisms. Other interventions, including interferons, glatiramer acetate, dimethyl fumarate, autologous hematopoietic stem cell transplantation, and vitamin D supplementation, may also modulate EBV-specific cellular or humoral responses, although the magnitude and durability of these effects vary. Emerging EBV-directed approaches, including EBV-specific T-cell therapy, inhibition of specific proteins, modulation of autophagy, and cholesterol-dependent viral latency, provide additional support for targeting EBV-related pathways in MS. Conclusions: The therapeutic efficacy of DMTs in MS may extend beyond nonspecific immunomodulation and involve partial disruption of EBV-driven immune persistence. Further controlled studies are required to validate EBV-related biomarkers and determine whether direct EBV-targeted therapies can provide sustained clinical benefit. Full article

Intercellular mitochondrial trafficking has emerged as an important mechanism influencing tumor progression, metabolic adaptability, and cancer cell plasticity. Beyond their classical bioenergetic functions, mitochondria act as central regulators of redox homeostasis, signaling pathways, and epigenetic remodeling. Increasing evidence suggests that mitochondria can be transferred between tumor, stromal, and immune cells through tunneling nanotubes (TNTs), extracellular vesicles (EVs), gap junctions, and cell fusion within the tumor microenvironment. This dynamic excshange enables metabolically compromised cancer cells to restore oxidative phosphorylation, optimize energy production, and survive under hypoxia and therapeutic stress. Mitochondrial transfer has been increasingly associated with enhanced cellular plasticity and adaptive phenotypic transitions, including the acquisition of stem-like features that contribute to tumor heterogeneity, metastasis, and treatment resistance. In addition to bioenergetic restoration, transferred mitochondrial DNA and metabolites participate in retrograde signaling, linking metabolic state to epigenetic regulation and transcriptional reprogramming. This metabolic epigenetic interplay supports tumor cell adaptation to environmental stress and therapeutic pressure. Although significant progress has been made, the precise mechanisms governing mitochondrial integration and their long-term impact on cellular phenotypes remain incompletely understood. A deeper understanding of these processes may reveal novel therapeutic strategies to disrupt tumor adaptability and progression. Specifically, targeting intercellular mitochondrial trafficking and its associated metabolic and epigenetic effects could help limit tumor plasticity, overcome treatment resistance, reduce disease recurrence, and improve overall clinical outcomes in cancer patients. Full article

Fructose 1,6-bisphosphatase 2 (FBP2) is a multifunctional protein whose cellular functions depend on its oligomeric state. Forced FBP2 tetramerization has been linked to microtubule disruption and impaired mitochondrial trafficking, accompanied by abnormal mitochondrial morphology. Here, we identify MIC60 (mitofilin), a core element of the mitochondrial contact site and cristae organizing system (MICOS), as a potential mediator of these effects. Using proximity ligation assay, protein crosslinking combined with mass spectrometry, and ultrastructural analysis, we demonstrate that FBP2 is in close proximity to MIC60 under basal conditions and this proximity is reduced upon FBP2 tetramerization or partial FBP2 depletion. Loss of this proximity coincides with marked remodeling of inner-membrane ultrastructure. These findings are consistent with a working model in which dimeric FBP2 contributes to the coordination of microtubule-dependent mitochondrial positioning with MICOS-linked intramitochondrial organization, providing a plausible mechanistic bridge between metabolic cues (AMP/NAD⁺) and mitochondrial structural integrity. Full article

Serotonin (5-HT) signaling is strictly controlled by the serotonin transporter (SERT). The present study aims to establish optogenetic approaches for the control of SERT localization and function by modulating the interaction between SERT and its regulatory protein, soluble guanylate cyclase (sGC). We generated several cell lines that stably express blue light-inducible optogenetic elements fused to sGC or the fourth internal loop (IL4) motif of SERT. Our results indicated that blue light-induced SERT-sGC interaction by heterodimerizing SsrA embedded in the membrane-associated improved light-induced dimer (iLID) and SspB-sGCβ1 decreased SERT localization in the plasma membrane, thus reducing the maximum transport velocity of SERT without affecting its K_m for substrate. The light-induced subcellular redistribution of SERT was shown to be attributable to an interference of the SERT-sGC interaction with SERT trafficking but not PKC-mediated internalization. In addition, the light-induced SERT-sGC interaction was blocked by the IL4 peptide or a mutation in the IL4 motif. Furthermore, light-induced exposure of the IL4 motif in iLID decreased the SERT-sGC interaction by displacing SERT from the SERT-sGC complex, thus increasing SERT localization in the membrane and elevating its ability for substrate uptake. This study achieved light-inducible modulation of the protein–protein interaction that allows for the study of biochemical and cellular processes in live cells. Full article

Background/objectives: This study presents a mechanistic assessment of an anti-HSPG2 monoclonal antibody (AM6) as an antibody–drug conjugate (ADC) carrier in vitro. Methods: Using live-cell confocal imaging with pathway inhibitors, we qualitatively characterized AM6 internalization and trafficking and compared linker/payload configurations for intracellular delivery and in vitro cytotoxicity. Results: AM6 exhibited rapid cellular entry in MDA-MB-231-LM2 cells, with contributions from clathrin-mediated endocytosis and macropinocytosis, followed by accumulation in endo-lysosomal compartments. Consistent with these trafficking observations, AM6 ADCs bearing cleavable linkers and a potent payload (MMAE) produced more pronounced antiproliferative effects in MDA-MB-231-LM2 and other HSPG2-positive tumor cells than non-cleavable constructs, whereas doxorubicin-based ADCs showed limited activity and greater aggregation risk. Conclusions: Overall, the data inform linker/payload selection and highlight considerations for future work, including quantitative internalization, antigen-negative or knockdown controls, and in vivo pharmacology. Full article

Background/Objectives: CTLA-4 is a key checkpoint of peripheral immune regulation, yet its biology cannot be reduced to inhibitory signaling alone. This review discusses CTLA-4 as a dynamic regulatory pathway shaped by ligand handling, intracellular trafficking, recycling, and cell-type-specific function, and examines how these features link molecular mechanism to human disease and therapy. Methods: We synthesized the structural, mechanistic, translational, and clinical literature spanning CTLA-4 molecular biology, cell-type-specific function, inborn errors of immunity, polygenic autoimmunity, transplantation, cancer immunotherapy, and immune-related adverse events. Results: CTLA-4 function depends on surface availability, trans-endocytosis of CD80/CD86, and tight control of endosomal trafficking. These features help explain why CTLA-4 haploinsufficiency, LRBA deficiency, and DEF6 deficiency converge clinically despite different upstream lesions, and why subtler CTLA-4 variation contributes to polygenic autoimmunity. Therapeutic studies also provide mechanistic insight. Abatacept can partly replace pathway function in monogenic disease, whereas belatacept highlights the limits of ligand blockade when endogenous coinhibition is also lost. In oncology, anti-CTLA-4 antibodies act through a more complex interplay involving checkpoint blockade, Fc biology, intratumoral Treg depletion, and receptor recycling. Emerging next-generation agents aim to retain antitumor activity while reducing systemic toxicity through more selective use of these mechanisms. Conclusions: Rather than a static inhibitory receptor, CTLA-4 is better viewed as a context-dependent regulatory pathway whose function depends on trafficking, surface availability, and cellular context. This perspective links molecular mechanism to clinical phenotype and supports more precise CTLA-4-targeted therapy. Full article

Natural killer (NK) cells are increasingly recognized as a complementary platform to T-cell-based cancer immunotherapies. Their innate, MHC-unrestricted recognition, capacity to mediate antibody-dependent cellular cytotoxicity (ADCC) and comparatively favorable toxicity profile have given rise to a broad therapeutic pipeline that includes cytokine-supported regimens, adoptive NK products, bispecific and trispecific NK engagers, and chimeric antigen receptor (CAR)-engineered NK cells. Clinical data, particularly in hematologic malignancies, show that NK-cell-based strategies can be safe and biologically active, although limited persistence, suboptimal trafficking and immune escape remain key challenges. Nasopharyngeal carcinoma (NPC), an Epstein–Barr virus (EBV)-driven epithelial cancer, illustrates how a tumor microenvironment (TME) can simultaneously impair NK function and create specific vulnerabilities that NK-focused therapies can exploit. This review summarizes NK biology and current therapeutic platforms, analyzes major limitations, highlights the specific context of NK-cell-based strategies in NPC and compares NK- and T-cell-based therapies with an emphasis on clinical translation. Full article