Search Results (165)

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

Background: Connexins (Cx) are a family of transmembrane proteins that form gap junctions and connexin hemichannels (HCs), enabling direct intercellular communication within the nervous system. Connexin 43 (Cx43), the principal astrocytic connexin, exhibits a context-dependent dual role: under physiological conditions it maintains tissue homeostasis and metabolic support, whereas under pathological conditions excessive activation of Cx43 hemichannels promotes neuroinflammation, excitotoxicity, blood–brain barrier disruption, and secondary neural tissue damage. Other connexin isoforms also contribute to the pathogenesis of neurological and psychiatric disorders through alterations in neuronal synchronization, glial signaling, and myelin integrity. Objective: To systematize current evidence on the role of key connexin isoforms in acute nervous system injuries—including stroke, traumatic brain injury, spinal cord injury, and peripheral nerve injury—as well as chronic disorders such as neurodegenerative diseases, epilepsy, and psychiatric disorders, with particular emphasis on the functional duality of connexin channels and the therapeutic potential of their selective modulation. Methods: A systematic literature search was conducted in the PubMed, Scopus, and Web of Science databases in accordance with the PRISMA framework and the PRISMA Extension for Scoping Reviews guidelines. The review included data from experimental models, postmortem brain studies, genetic association analyses, and pharmacological intervention studies. The retrieved studies were screened, assessed for eligibility, and integrated using a qualitative narrative synthesis approach. Results: In acute neural injuries, hyperactivation of Cx43 hemichannels amplifies inflammatory signaling, edema formation, and neuronal death, whereas selective HCs inhibitors reduce lesion volume and improve functional outcomes in experimental models. Connexin 36 (Cx36) contributes to cortical spreading depolarization and seizure propagation, while Connexin 32 (Cx32) and Connexin 47 (Cx47) are critically involved in oligodendrocyte function and white-matter demyelination. In PNI, Cx43 upregulation contributes to neuropathic pain, whereas mutations in Cx32 cause hereditary demyelinating neuropathies. In neurodegenerative diseases—including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis—Cx43 hemichannel activity promotes neuroinflammation and pathological protein accumulation, while reduced Cx32/Cx47 expression disrupts metabolic support of axons. In psychiatric disorders such as major depressive disorder, bipolar disorder, and schizophrenia, decreased astrocytic connexin expression (Cx43 and Cx30) has been associated with impaired glial–neuronal communication and cognitive–emotional dysfunction. In epilepsy, increased Cx43/Cx30 expression contributes to neuronal hypersynchronization and blood–brain barrier dysfunction, whereas selective hemichannel blockade suppresses seizure activity. Conclusions: Cx—particularly Cx43—occupies a central position in the molecular mechanisms of secondary neural injury and network dysfunction. The dual functional properties of gap junctions and hemichannels determine their context-dependent effects across neurological and psychiatric diseases. Selective inhibition of pathological HCs activity shows significant neuroprotective and anticonvulsant potential and represents a promising direction for the development of targeted therapeutic strategies. Further studies are required to determine optimal therapeutic time windows, tissue-specific effects, and the long-term safety of Cx modulation. Full article

Melanoma is a highly malignant neoplasm of the skin with early metastatic spread and increasing incidence worldwide. Although there are significant therapeutic advances in immunotherapy, especially with the checkpoint inhibitors targeting PD-1 and CTLA-4, challenges such as treatment-related toxicities, a heterogeneous response to therapy, and drug resistance continue to exist. There are unmet needs for novel therapeutic strategies and/or approaches to complement the existing treatment options. Potential targets for future melanoma treatment are the gap junction proteins, connexins, which show an altered pattern of regulation during melanoma progression. In this review, we highlight the regulation of gap junctions during melanoma progression and the characterization of gap junctions as tumor suppressors during early-stage tumor development and then the reversion to enhancers of tumor metastasis during late-stage melanoma progression. We provide a comprehensive overview of gap junctions in the skin and how the connexin proteins, which comprise gap junctions, are alternatively regulated in melanoma progression. Connexins are protein channels in the human body that consist of 21 isoforms. These isoforms form gap junctions that provide important intercellular signaling and permeability channels. Each connexin protein consists of four transmembrane domains and a C-terminal tail, which is an important part of its function and regulation. Permeants of gap junctions include signaling molecules such as cyclic AMP and inositol triphosphate which are linked to key cellular behaviors such as proliferation and migration, making them essential for several tumor-related processes. At least ten connexin isoforms are found in normal skin. Connexin 43 (Cx43) is classified as the most prevalent isoform while Connexin 26 (Cx26) has been reported to be more specialized with restricted expression patterns. Cx43 and Cx26 regulate the growth, differentiation, and repair of the epidermis after injury. Evidence suggests that connexins have a stage-related function in melanoma. Loss of connexin expression and gap junctional intercellular communication is linked to tumor suppression and loss of differentiation in early-stage melanoma, while re-expression or overexpression of specific connexins, notably Cx43, may promote metastasis through enhanced tumor–stromal interactions and increased motility in late-stage melanoma. Such opposing actions of connexins support their candidacy as biomarkers and therapeutic targets. Understanding the dual-stage related functions of connexins in melanoma development and progression may lead to less cytotoxic and more efficient future therapeutic approaches. Full article

Growth stagnation or weight loss is prevalent in weaned piglets, with post-weaning diarrhea severely compromising intestinal health, underscoring the criticality of intestinal structural integrity for preventing digestive disorders. Tight junction proteins (TJPs), core components of intestinal intercellular junctions, play indispensable roles in maintaining barrier function, nutrient absorption, and intestinal homeostasis by regulating paracellular permeability and mediating immune defense-related signaling pathways. Dysregulated TJP expression disrupts these processes and impairs piglet growth performance. Despite recent progress in characterizing TJP-mediated regulation of intestinal health in weaned piglets, key knowledge gaps remain regarding the specific regulatory mechanisms by which distinct TJP subtypes modulate intestinal microbiota–immune crosstalk. Future research should prioritize elucidating the effects of nutritional interventions on TJP expression and intestinal health, as well as the molecular mechanisms underlying TJP involvement in intestinal diseases. These efforts will provide theoretical support for developing novel feed additives and nutritional strategies to improve weaned piglet health. Full article

Plant extracts are rich in various bioactive compounds, such as polyphenols, flavonoids, tannins, terpenoids, phenolic acids, saponins, alkaloids, and polysaccharides. Antioxidant polyphenols are increasingly attracting attention, not only as dietary components but also as valuable food industry byproducts. Resveratrol, present in a wide range of plants, is well recognized for its diverse biological activities, including antioxidant, antitumor, cardioprotective, and neuroprotective effects. Given the importance of intercellular communication in these physiological processes, gap junctions (GJs) composed of connexin (Cx) family proteins are of particular interest because they provide a direct pathway for electrical and metabolic signaling and are key players in maintaining normal organ function and cell development. Aberrations of GJ intercellular communication (GJIC) may result in the progression of cardiovascular and neurological diseases and tumorigenesis. Cx43 and Cx45 play crucial roles in cardiac excitation and contraction, and alterations in their expression are associated with disrupted impulse propagation and the development of arrhythmias. In this study, for the first time, we performed a comparative analysis of the effect of resveratrol on Cx43 and Cx45 GJIC using molecular modeling, a dual whole-cell patch-clamp technique to directly measure GJ conductance (g_j), and other approaches. Our results revealed that resveratrol accomplished the following: (1) inhibited GJ g_j in Cx43- but enhanced it in Cx45-expressing HeLa cells; (2) exerted dose- and time-dependent changes in Cx expression and plaque size; (3) reduced cell viability and proliferation; (4) and altered Cx43 phosphorylation patterns linked to gating and plaque stability. Overall, resveratrol modulates GJIC in a dose-, time-, and connexin type-specific manner. Full article

Background/Objectives: The meninges, the protective membranes covering the central nervous system, undergo complex developmental processes that are critical for CNS integrity and function. Connexin 37 (Cx37) and 40 (Cx40), members of the connexin family of gap junction proteins, have been implicated in various physiological and pathological processes. They play a critical role in cell–cell communication. The aim of our study was to investigate the expression of connexins Cx37, Cx40, and Panx1 in the meninges of both human and murine models (yotari and wild type) at the 6th week/E13.5 and 8th week/E15.5 of developmental stages. Methods: Human embryonic tissues (6th–8th week, n = 4 for the 6th week and n = 4 for the 8th week) and mouse embryos (yotari Dab1⁻/⁻ and wild type, E13.5–E15.5) were collected and fixed in 4% paraformaldehyde. Paraffin sections were stained for Cx37, Cx40, and Panx1 using immunofluorescence. Images were analyzed in ImageJ, and statistical comparisons were performed using one-way ANOVA with Tukey’s post hoc test (p < 0.05). Results: Cx37 was consistently expressed across all developmental stages, with the highest threshold area percentage observed at E13.5 and E15.5 in murine leptomeninges, demonstrating statistically significant differences compared to controls (p < 0.05) and notably from corresponding human stages (p < 0.001). Strong Cx37 staining intensity at E13.5 was noted in both wild-type and yot mice, while human leptomeninges displayed mild staining at the 6th week of development. In contrast, both human and murine pachymeninges exhibited moderate Cx37 expression. Additionally, the expression of Cx37 in wild-type mice surpassed that of human samples at both E13.5 and E15.5 stages (p < 0.01 and p < 0.001, respectively). For the developing dura mater, Cx37 expression peaked at E15.5 in yot mice, significantly different from both wild-type and human dura mater (p < 0.01 and p < 0.05). Cx40 expression was highest in the leptomeninges at E15.5. Panx1 was similarly expressed across stages, with the highest threshold area percent observed in wild-type leptomeninges and pachymeninges at E15.5, showing significant differences compared to yot mice and human samples (p < 0.05). Both leptomeninges and pachymeninges exhibited mild Panx1 staining at E13.5, while stronger staining was observed at E15.5 in murine samples, contrasting with mild intensity in human counterparts. Conclusions: These findings highlight the implications of Dab1 deficiency for the expression of gap junction proteins during meninges development, implicating their importance in intercellular communication that is essential for normal meningeal and neurodevelopmental processes. Full article

Effective communication between multipotent mesenchymal stromal cells (MSCs) and endothelial cells (ECs) plays a critical role in the regulation of angiogenesis, especially under conditions of hypoxia. In addition to paracrine stimulation, direct intercellular contacts play an important role in the angiogenic interaction between MSCs and ECs, making them an important target for modulating vascular network restoration under ischemic conditions. The aim of this study was to determine the contribution of gap junctions (GJs) to the angiogenic response of MSCs and the EA.hy926 cell line (an Endothelial Cell Model) under acute hypoxic stress. In a cell co-culture model at 0.1% O₂ using a specific GJ inhibitor (carbenoxolone), molecular, cellular, and functional tests were performed: assessment of viability, proliferation, migration, secretion of angiogenic mediators, and expression of crucial genes. GJ blockade was accompanied by decreases in the proliferation and migration activity and angiogenic potential of the conditioned medium in in vitro and in ovo tests. These data highlight the importance of the GJ in coordinating the angiogenic response in conditions of acute hypoxia and can be used to develop protocols for regenerative medicine. Full article

Radiotherapy (RT) remains a cornerstone of cancer treatment, offering spatially precise cytotoxicity against malignant cells. However, emerging evidence reveals that ionizing radiation (IR) exerts biological effects beyond the targeted tumor volume, manifesting as radiation bystander effects (BEs) and other non-targeted effects (NTEs). These phenomena challenge the traditional paradigm of RT as a localized intervention, highlighting systemic and long-term consequences in non-irradiated tissues. This comprehensive review synthesizes molecular, cellular, and clinical insights about BEs, elucidating the complex intercellular signaling networks gap junctions, cytokines, extracellular vesicles, and oxidative stress that propagate damage, genomic instability, and inflammation. We explore the role of mitochondrial dysfunction, epigenetic reprogramming, immune modulation, and stem cell niche disruption in shaping BEs outcomes. Clinically, BEs contribute to neurocognitive decline, cardiovascular disease, pulmonary fibrosis, gastrointestinal toxicity, and secondary malignancies, particularly in pediatric and long-term cancer survivors. The review also evaluates countermeasures including antioxidants, COX-2 inhibitors, exosome blockers, and FLASH RT, alongside emerging strategies targeting cfCh, inflammasomes, and senescence-associated secretory phenotypes. We discuss the dual nature of BEs: their potential to both harm and heal, underscoring adaptive responses and immune priming in specific contexts. By integrating mechanistic depth with translational relevance, this work posits that radiation BEs are a modifiable axis of RT biology. Recognizing and mitigating BEs is imperative for optimizing therapeutic efficacy, minimizing collateral damage, and enhancing survivorship outcomes. This review advocates for a paradigm shift in RT planning and post-treatment care, emphasizing precision, personalization, and systemic awareness in modern oncology. Full article

Synchronized oscillatory fluctuations in intracellular calcium concentration across extended neuronal networks represent a functional indicator of connectivity and signal coordination. In this study, a model of human immature neurons (differentiated from LUHMES precursors) has been used to establish a robust protocol for generating reproducible intracellular Ca²⁺ oscillations in both two-dimensional monolayers and three-dimensional spheroids. Oscillatory activity was induced by defined ionic conditions in combination with potassium channel blockade. It was characterized by stable frequencies of approximately 0.2 Hz and high synchronization indices across millimeter-scale cultures. These properties were consistently reproduced in independent experiments and across laboratories. Single-cell imaging confirmed that oscillations were coordinated throughout large cell populations. Pharmacological interventions demonstrated that neither excitatory nor inhibitory chemical synaptic transmission influenced oscillatory dynamics. Gap junction blockers completely disrupted synchronization, while leaving individual cell activity unaffected. Functional dye-transfer assays provided additional evidence for electrical coupling. This was further supported by connexin-43 expression profiles and immunostaining. Collectively, these findings indicate that synchronized Ca²⁺ oscillations in LUHMES cultures are mediated by gap junctional communication rather than by conventional synaptic mechanisms. This system offers a practical platform for studying fundamental principles of network coordination and for evaluating pharmacological or toxicological modulators of intercellular coupling. Moreover, it may provide a relevant human-based model to explore aspects of neuronal maturation and to assess compounds with potential neurodevelopmental toxicity. Full article

Traumatic brain injury (TBI) is one of the most common forms of neurotrauma, accompanied by significant disruptions in neuronal homeostasis and intercellular communication. A key protein involved in these processes is connexin 43 (Cx43), which facilitates the formation of gap junctions in the astrocytic network. In this study, using confocal and immunofluorescence microscopy, ultrastructural analysis, and molecular modeling, we investigated the dynamics of Cx43 expression and structural changes in neuroglia during various post-traumatic periods following TBI. It was shown that in the acute phase, 24 h post-injury, there is a reduction in Cx43 expression, accompanied by apoptotic neuronal degradation, disruption of nuclear NeuN localization, and destruction of cellular ultrastructure. By 7 days post-injury, a significant increase in Cx43 levels was observed, along with the formation of protein aggregates associated with pronounced reactive astrogliosis. Peripheral blood analysis revealed persistent neutrophilia, lymphopenia, and reduced monocyte levels, reflecting a systemic inflammatory response and immunosuppression, which was corroborated by a custom-trained neural network-based computer vision model. Linear regression and correlation analyses further identified a strong positive association between normalized monocyte levels and Cx43 expression, a moderate negative correlation with lymphocytes, and no significant correlation with neutrophils. Using a custom-built computer vision model, we confirmed these hematological trends and detected subtle changes, such as early increases in platelet counts, that were not captured by manual evaluation. The model demonstrated strong performance in classifying common blood cell types and proved to be a valuable tool for monitoring dynamic post-traumatic shifts in blood. Molecular dynamics modeling of Cx43 identified a pH-dependent mechanism of conformational reorganization under post-traumatic acidosis, mediated by the interaction between protonated His142 and Glu103. This mechanism mimics the structural consequences of the pathogenic E103K mutation and may play a critical role in the neurotoxic effects of Cx43 in TBI. These findings highlight the complexity of Cx43 regulation under traumatic conditions and its potential significance as a target for neuroprotective therapy. Full article

After delivering my Keynote address to the young scientists at the International Gap Junction meeting, “International Colloquium on Gap Junctions and Cancer: Discussing how cellular communication modifies carcinogenesis and cancer treatment outcomes” (San Paulo, Brazil, 10–14 July 2023), I was asked to condense the talk into a manuscript covering the 50+ years of my scientific journey of basic biomedical research. While this journey had to omit so many important experiences, people and external events, I have tried to illustrate how my initial motivation, personal perspective of my abilities, and naïve goal as a young scientist did not prepare me for the non-linear path to where I ended. That path had many twists, turns, barriers, disappointments, surprises and wrong directions, as well as associations with co-workers, students and collaborators who afforded me with great wisdom, support and technical advice. In the history of science, few individuals have left their footprints in a straight path; however, my early education in human evolutionary genetics provided me a strong background framework, on which multiple other acquired disciplines, forced by circumstances along my uneven journey, allowed me to grow intellectually, as well as making me aware of my limitations. As my late mentor, Dr. Van Rensselaer Potter said: “… humility with responsibility”. At the completion of my experimental journey, I continued to reflect on the implied meanings of my and others’ results to view the current state of collected knowledge on global health issues as one of all scientists’ obligations, namely, to weigh the value and bioethical implications of our work to global society. “ Full article

Particulate matter (PM), mainly PM_0.5, represents a significant concern for human health, particularly relating to lung homeostasis, and more research is required to ascertain its tissue tropism and the molecular pathways involved. In this study, we first focus on classical in vitro toxicological endpoints (cytotoxicity and cell growth) in human bronchial and alveolar epithelial cell lines mimicking the two pulmonary target tissues. Air samples were collected in five Italian cities (Brescia, Lecce, Perugia, Pisa, Turin) during winter and spring. To better decipher the PM_0.5 effects on pulmonary cells, a further winter sampling was performed in Brescia, and studies were extended to assess tumour promotion, oxidative stress, and the activity of Matrix metalloproteases (MMP). The results confirmed that the effect of air pollution is linked to the seasons (winter is usually more cytotoxic than spring) and is correlated with the peculiar characteristics of the cities studied (meteoclimatic conditions, economic/anthropogenic activities). Alveolar cells were often less sensitive than bronchial cells. All PM samples from Brescia inhibited intercellular communication mediated by gap junctions (GJIC), increased the total content in glutathione, and decreased the reduced form of glutathione, whereas the Reactive Oxygen Species (ROS) content was almost constant. Long-term treatments at higher doses of PM decreased MMP2 and MMP9 activity. Taken together, the results confirmed that PM is cytotoxic and can potentially act as tumour promoters, but the mechanisms involved in oxidative stress and lung homeostasis are dose- and time-dependent and quite complex. Full article

Long-range intercellular communication is essential for multicellular biological systems to regulate multiscale cell–cell interactions and maintain life. Growing evidence suggests that intercellular calcium waves (ICWs) act as a class of long-range signals that influence a broad spectrum of cellular functions and behaviors. Importantly, mechanical signals, ranging from single-molecule-scale to tissue-scale in vivo, can initiate and modulate ICWs in addition to relatively well-appreciated biochemical and bioelectrical signals. Despite these recent conceptual and experimental advances, the full nature of underpinning mechanotransduction mechanisms by which cells convert mechanical signals into ICW dynamics remains poorly understood. This review provides a systematic analysis of quantitative ICW dynamics around three main stages: initiation, propagation, and regeneration/relay. We highlight the landscape of upstream molecules and organelles that sense and respond to mechanical stimuli, including mechanosensitive membrane proteins and cytoskeletal machinery. We clarify the roles of downstream molecular networks that mediate signal release, spread, and amplification, including adenosine triphosphate (ATP) release, purinergic receptor activation, and gap junction (GJ) communication. Furthermore, we discuss the broad pathophysiological implications of ICWs, covering pathophysiological processes such as cancer metastasis, tissue repair, and developmental patterning. Finally, we summarize recent advances in optical imaging and artificial intelligence (AI)/machine learning (ML) technologies that reveal the precise spatial-temporal-functional dynamics of ICWs and ATP waves. By synthesizing these insights, we offer a comprehensive framework of ICW mechanobiology and propose new directions for mechano-therapeutic strategies in disease diagnosis, cancer immunotherapies, and drug discovery. Full article

During mouse pregnancy, the pubic symphysis (PS) undergoes a gradual transitioning into an interpubic ligament (IpL) for a successful delivery. After birth, this IpL is rapidly remodeled, returning to the non-pregnant morphology. The PS fibrocartilaginous cells acquire a myofibroblast-like phenotype, characterized by extracellular matrix (ECM) secretion, expression of α-smooth muscle actin (α-SMA), and vimentin. While the presence of myofibroblast-like cells during the IpL remodeling is well described, cell–cell interactions and how this might contribute to the delivery remains poorly understood. This study uses ultrastructure and molecular approaches to investigate cell–cell and cell–ECM junctions during mouse pregnancy and postpartum. Our findings reveal that the intercellular contacts between adjacent IpL myofibroblast-like cells, particularly at late pregnancy stages, are characterized as adherens and GAP junctions. The acquisition of contractile elements by IpL cells, coupled with neighboring cells and the surrounding ECM via junctional complexes, suggests an important role in supporting changes in the mechanical forces generated by pubic bone movements during mouse pregnancy and also in tying the pelvic bones together, which may help the birth canal closure after delivery. Further studies in PS biology may investigate fibroblast to myofibroblast differentiation signaling cascades, which regulate the expression of pro-fibrotic proteins and may provide new insights for preterm labor. Full article

Hypoxia is a critical factor affecting tissue homeostasis that dramatically alters the tumor microenvironment (TME) through genetic, metabolic, and structural changes, promoting tumor survival and proliferation. Hypoxia-inducible factor-1α (HIF-1α) plays a central role in this process by regulating hundreds of genes involved in the processes of tumorigenesis, angiogenesis, metabolic reprogramming, and immune evasion. This review provides a comprehensive examination of the role of HIF-1α in hypoxia and how hypoxia weakens intercellular junctions—including gap junctions, adherens junctions, tight junctions, and desmosomes. The disruption of gap junctions decreases intercellular communication, which alters signal transduction cascades and tumor suppressive properties. Adherens junctions are comprised of proteins that characterize the tissues and link cells to the actin cytoskeleton, whereby their disruption promotes the epithelial-to-mesenchymal transition (EMT). Under hypoxic conditions, the tight junction proteins are dysregulated, altering paracellular transport and cell polarity. In addition, desmosomes provide linkage to intermediate filaments, and hypoxia compromises tissue integrity. Collectively, the influence of hypoxia on cellular junctions promotes tumorigenesis through reducing cell communication, cytoskeletal interactions, and altering signaling pathways. Activation of matrix metalloproteinases (MMPs) further degrades the extracellular matrix and enhances tumor invasion and metastasis. This process also involves hypoxia-induced angiogenesis, regulated by HIF-1α. A comprehensive understanding of the mechanisms of hypoxia-driven tumor adaptation is essential for developing effective therapeutic strategies. Furthermore, this review examines current treatments aimed at targeting HIF-1α and explores future directions to enhance treatment efficacy and improve patient outcomes. Full article