Polyploid giant cancer cells: A novel target in future cancer therapy.

Zein/Fucoidan microcarriers promote myogenic differentiation via topographical cues and hydrodynamic modulation.

Severe acute respiratory syndrome coronavirus 2 infects host cells through binding of the spike protein receptor-binding domain (RBD) to the human angiotensin-converting enzyme 2 receptor. In this study, the antiviral activity of 14 catechin derivatives was evaluated using a pseudovirus assay that emulates spike-mediated cell fusion. Of these, gallocatechin gallate, epigallocatechin gallate, epigallocatechin 3-(3″-O-methyl) gallate, and epigallocatechin exhibit strong inhibitory effects on infection. A structural comparison of the compounds revealed that catechins with a pyrogallol-type B-ring configuration exhibited greater inhibitory effects than their catechol-type counterparts. Docking simulations demonstrated that the hydroxyl group at the 5-position of the B-ring forms a hydrogen bond with Gln493 on the spike RBD, thereby facilitating additional stabilizing interactions with adjacent residues, such as Tyr453. Although catechin bioavailability is low, the results of this study suggest that regular consumption or gargling may offer localized antiviral activity at mucosal surfaces, such as those found in the oral or nasal cavity, because the catechin concentrations used in the cell assays are similar to those observed in green tea (100µM). This study underscores the potential of pyrogallol-type catechins to act as antiviral agents.

MyoFuse is a fully AI-based workflow for automated quantification of skeletal muscle cell fusion in vitro.

ABSTRACTCell fusion requires the activity of several phagocytic receptors and the temporary exposure of phosphatidylserine (PS) on the surface of viable myoblasts. Recently, we reported that these receptors turn myoblasts into potent phagocytic cells. Since cell fusion and phagocytosis share many molecules and mechanisms in myoblasts, we aimed to investigate how myoblasts choose between the two pathways during fusion. To prevent accidental uptake, viable cells express “don't eat‐me” signals. By analyzing RNA sequencing data, we found that differentiation affected the expression of multiple “don't eat‐me” genes in the C2C12 mouse myoblast cells, including upregulation of Sirpα, a receptor for CD47. The same was observed in differentiating myoblasts in vivo following cardiotoxin‐induced injury in mouse skeletal muscle. Treatment of differentiating C2C12 cells with anti‐CD47 antibody significantly reduced cell fusion but did not affect cell survival or differentiation. Both CD47 and SIRPα appeared at contact points of fusing myoblasts. Blocking CD47 signaling increased the uptake of viable red blood cells but only slightly increased the uptake of viable myoblasts. Blocking thrombospondin‐1, another CD47 ligand, also inhibited fusion. Inhibiting CD47 signaling did not impact the engulfment of apoptotic cells. However, long‐term exposure to continuously PS‐expressing apoptotic cells disrupted myotube formation by inhibiting PIEZO1 activation, leading to syncytia formation. Overall, our data show that differentiating myoblasts upregulate CD47 to avoid accidental phagocytosis of live cells but mainly to promote myoblast fusion. Therefore, the activity of this signaling pathway contributes to the decision‐making between the two processes that would compete with each other during myoblast differentiation.

Gestational hyperglycemia (GHG) causes fetal growth restriction (FGR), while its mechanism remains incompletely understood. Defects in the syncytiotrophoblast, which is pivotal for maternal-fetal substance exchange, adversely affect fetal development. Whether dysfunction in syncytiotrophoblast is involved in GHG-related FGR remains unclear. In this study, we used an STZ-induced GHG mouse model and found that GHG-induced FGR (44.5% reduction in fetal weight) was associated with a 28.3% decrease in placental efficiency. Immunofluorescence and transmission electron microscopy examinations revealed defective formation of the syncytiotrophoblast layer in GHG placenta, resulting from impaired fusion of trophoblast cells. Gene expression profiling and staining analysis of the placenta revealed that Tim1, a phosphatidylserine-binding protein, was 43.5% downregulated in GHG placenta. In vitro studies confirmed that hyperglycemia decreased Tim1 and led to trophoblast fusion defects. Tim1 silence alone recapitulated the effects of hyperglycemia on trophoblast fusion, while Tim1 overexpression rescued the anti-fusion effects of hyperglycemia. Moreover, we generated a Tim1 knockout mouse strain, and observed that Tim1 deficiency alone induced defective formation of syncytiotrophoblast and FGR during pregnancy. Further analysis revealed that Tim1 was downregulated by hyperglycemia-related oxidative stress. Antioxidant treatment during pregnancy reversed Tim1 downregulation, promoted syncytiotrophoblast formation and improved FGR. Finally, the reduction of TIM1 expression was confirmed in human placenta with pre-gestational diabetes and FGR. These findings suggest that Tim1 downregulation in GHG inhibits placental syncytiotrophoblast formation and contributes to FGR.

This study aimed to investigate the effects of soluble epoxide hydrolase (sEH) inhibition on osteoclast differentiation and activity in vitro and in vivo, as well as to elucidate the signaling pathways associated with osteoclastogenesis. Primary murine bone marrow monocytes were stimulated with macrophage colony-stimulating factor and receptor activator of nuclear factor kappa B ligand to induce osteoclastogenesis and treated with the sEH inhibitor 1-(1-propanoylpiperidin-4-yl)-3-[4-(trifluoromethoxy)phenyl]urea (TPPU) (0.1-10 μM). Tartrate-resistant acid phosphatase staining, gene expression analyses, and immunofluorescence were used to evaluate osteoclast formation, transcriptional regulation, and cell fusion. A murine model of ligature-induced periodontitis was used to assess in vivo effects of sEH inhibition (TPPU 10 mg/kg). Alveolar bone loss was quantified by histomorphometry, and gingival gene expression was analyzed. In vitro, sEH inhibition significantly reduced tartrate-resistant acid phosphatase-positive multinucleated osteoclast formation, downregulated the expression of key transcription factors and osteoclast activity-related genes. Immunofluorescence analysis revealed attenuation of mitogen-activated protein kinase signaling and reduced dendritic cell-specific transmembrane protein expression, indicating impaired cell fusion. In vivo, TPPU treatment preserved alveolar bone structure, reduced osteoclast-like cell numbers, and decreased the expression of osteoclastic markers in gingival tissues during experimental periodontitis. sEH acts as a crucial regulator of osteoclast differentiation and function. Pharmacological inhibition of sEH suppresses osteoclastogenesis and protects against inflammatory bone loss. Therefore, targeting sEH may represent a novel therapeutic approach to modulate osteoclast activity and prevent bone destruction in periodontitis and other bone-resorptive diseases. SIGNIFICANCE STATEMENT: This study provides direct evidence that soluble epoxide hydrolase inhibition modulates osteoclast differentiation and fusion, contributing to reduced inflammatory bone loss. By demonstrating effects on osteoclast-intrinsic pathways while also influencing the inflammatory microenvironment, our findings support soluble epoxide hydrolase as a pharmacological target for chronic inflammatory bone-resorptive diseases.

Oxidative stress-induced lipid peroxidation products (LPPs), particularly 4-hydroxy-nonenal (4-HNE) and 4-oxo-nonenal (4-ONE), have recently gained attention for their direct regulation of ion channels essential for pain signaling. In this study, we investigated how these two LPPs affect the electrophysiological properties of neurons, specifically voltage-gated sodium (NaV) channels, thereby influencing sensory neuron excitability and pain pathways. Using human neuroblastoma (SH-SY5Y) and ND7/23 cells (a fusion cell line exhibiting partial sensory neuron properties), we measured changes in NaV channel-mediated sodium currents following treatment with 4-HNE or 4-ONE. Whole-cell patch-clamp experiments showed that 4-ONE (10 µM) and 4-HNE (100 µM) did not significantly alter the peak sodium current amplitude in SH-SY5Y cells. However, in ND7/23 cells, both 4-HNE and 4-ONE induced a negative shift in NaV channel activation voltage dependence, enabling sodium channel activation at lower membrane potentials. Furthermore, current-clamp recordings in primary mouse dorsal root ganglion neurons demonstrated that treatment with 4-ONE and 4-HNE reduced the current threshold required to elicit action potentials and significantly increased action potential firing frequency. These findings indicate that LPPs enhance pain sensitivity by modulating NaV channels, which play a crucial role in pain transmission. In conclusion, 4-HNE and 4-ONE shift the voltage-dependent activation of sodium channels toward more negative potentials, thereby increasing the excitability of primary sensory neurons and amplifying pain signals. This study provides molecular insights into how oxidative stress-related lipid peroxidation contributes to sensory mechanisms and offers potential avenues for developing new treatments for oxidative stress- or inflammation-associated pain.

Fluridone (FLU), a commonly used aquatic herbicide in water environmental management, poses threats to aquatic ecosystems and aquatic product safety due to issues of misuse, abuse, and residues. Therefore, it is necessary to develop highly sensitive detection methods. Here, two novel FLU haptens with distinct spacer arms were rationally designed, and the best scheme was selected through computer-aided chemical simulations. Through mouse immunization and cell fusion techniques, a high-affinity, specific antibody against FLU (mAb-2B2) was obtained. The affinity constant (Ka) and maximal half-inhibitory concentration (IC50) of mAb-2B2 were 3.72 × 109 L/mol and 0.50 ng/mL, respectively, with negligible cross-reactivity to six other analogues. Molecular docking analysis revealed that the key amino acid residues mediating the specific recognition of mAb-2B2 were primarily ARG 99 (at distances of 2.47, 3.88, and 2.80 Å), ARG 96 (at 3.56 Å), ARG 100 (at 5.32 Å), and TYR 91 (at 3.79 Å). Based on mAb-2B2, a gold nanoparticles-immunochromatographic strips (GNPs-ICS) method for detecting FLU residues in river water, crayfish, and fish samples was established for the first time, with detection ranges of 4.22-31.55 ng/mL, 13.61-65.01 μg/kg, and 5.51-35.40 μg/kg, respectively. This method was demonstrated to be suitable for rapid primary screening of FLU residues in environmental and aquatic products.

From development to cancer: Wnt/β-Catenin signaling in cell fusion and polyploid giant cancer cell formation.

Pheromone MAPK pathway regulates the yeast-to-hypha transition in the parasitic mushroom Naematelia sinensis in a cell fusion-independent manner.

Myomaker and ether lipids cooperate to promote fusion-competent membrane states.

Unveiling the role of PGCCs in tumor recurrence and therapeutic resistance: Hidden architects of cancer's comeback.

A mathematical model for temperature effects on virus-mediated cell fusion.

Tumor-immune hybrid cell biology: A review of its potential impact in oncology.

Mitochondria are the energy factories of a cell and mitochondrial morphology, quantity, membrane potential, and DNA copy number can change depending on metabolic requirements and/or genetic defects. Different mutations in mitochondrial DNA might affect mitochondrial morphology and membrane potential differently. In this study we investigated mitochondrial morphology and membrane potential in vitro in mesoangioblast-derived human myotubes harboring a pathogenic mtDNA mutation and analyzed mitochondrial behavior following fusion with healthy mesoangioblasts. Myotubes were differentiated in vitro from mesoangioblasts obtained from two mitochondrial myopathy patients, M02 (96% m.3271T>C) and M11 (73% m.3291T>C), and from a functionally healthy male control, M06 (3% m.3243A>G). On day 5 of differentiation, healthy male mesoangioblasts (mM06) were added to mutant myotube cultures to allow cell fusion. On day 11, mitochondrial morphology and membrane potential were assessed by three-dimensional live-cell imaging using spinning disk confocal microscopy with tetramethylrhodamine methyl ester (TMRM). Following live imaging, cells were fixed and subjected to Y-chromosome fluorescence in situ hybridization (FISH), enabling identification and retrospective analysis of hybrid (i.e., fused with male control mesoangioblasts) and non-hybrid (i.e., not fused with these control mesoangioblasts) myotubes within the same imaging fields. Quantitative image analysis at the level of individual myotubes revealed that, when normalized to sarcoplasmic volume, mitochondrial volume, object number, and membrane potential did not differ between mutant and control myotubes despite heteroplasmy levels exceeding 70%. Fusion of healthy mM06 mesoangioblasts did not impair myotube formation and resulted in redistribution of mitochondrial content without an increase in mitochondrial object number, consistent with integration of donor mitochondria into the existing mitochondrial network. Across conditions, mitochondrial parameters were strongly influenced by myotube size, underscoring the importance of accounting for biological variation when quantifying mitochondrial features. Together, these findings demonstrate that high mtDNA mutation loads do not necessarily alter mitochondrial morphology or membrane potential under standard in vitro differentiation conditions and provide mechanistic insight into mitochondrial behavior following mesoangioblast fusion in human myotubes. Fusion of healthy mesoangioblasts supports integration of donor mitochondria into the existing network without compromising myogenesis, consistent with mitochondrial mixing rather than replacement.

Skeletal muscle regeneration is a multistep process involving the activation, proliferation, differentiation, and fusion of muscle stem cells, known as satellite cells. Fusion of satellite cell-derived myoblasts (SCMs) is indispensable for generating the multinucleated, contractile myofibers during muscle repair. However, the molecular and cellular mechanisms underlying SCM fusion during muscle regeneration remain incompletely understood. Here, we reveal a critical role for branched actin polymerization in SCM fusion during mouse skeletal muscle regeneration. Using conditional knockouts of the Arp2/3 complex and its actin nucleation-promoting factors N-WASP and WAVE, we demonstrate that branched actin polymerization is specifically required for SCM fusion but dispensable for satellite cell proliferation, differentiation, and migration. We show that the N-WASP and WAVE complexes have partially redundant functions in regulating SCM fusion and that branched actin polymerization is essential for generating invasive protrusions at fusogenic synapses in SCMs. Together, our study identifies branched-actin regulators as key components of the myoblast fusion machinery and establishes invasive protrusion formation as a critical mechanism enabling myoblast fusion during skeletal muscle regeneration.

SUMMARY In the planozygotes of chlorophytes, parental flagella and eyespot(s) are generally arranged in a coordinated manner in the cell following the fertilization of biflagellate gametes. This phenomenon can be attributed to the process of gamete‐gamete fusion occurring at a specific location on the cell surface, which is designated as the mating structure/cell fusion site. Notably, this structure/site occupies distinct positions in the gametes of opposite mating types or sexes. To ascertain whether analogous cell fusion processes and planozygote formation are observed in species lacking eyespots, the fertilization of the markedly anisogamous marine green macroalga Codium fragile was observed using fluorescence microscopy, field emission‐scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM). Both the female and male gametes were biflagellate and, presumably, lacked the mating structure. Following the mixing of female and male gametes, the male gametes immediately gathered around the female gamete and adhered to its surface within 10 s. Subsequently, one male gamete entered the female gamete at the vicinity of the flagellar base, where the female nucleus was located. In the mating gametes, gamete‐gamete adhesion and fusion occurred between the lateral side of the male gamete, which was parallel to the flagellar beat plane, and the cell anterior of the female gamete, which was close to the flagellar base. This suggests that cell fusion occurred at the limited region of the gamete cell surface. Consequently, female and male flagella became a pair and showed a Y‐shaped arrangement in the planozygote when viewed from the cell anterior.

Palmitoylation is a reversible post‐translational modification that enhances protein hydrophobicity and regulates cellular functions such as trafficking and signaling. In humans, this modification is catalyzed by 23 DHHC enzymes, but the mechanisms by which they recognize their substrates remain unclear. The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike protein undergoes palmitoylation primarily by DHHC20 with subsequent modification by DHHC9 at 10 cytoplasmic tail (CT) cysteines, a modification crucial for membrane fusion and viral entry. Using AlphaFold2 modeling and site‐directed mutagenesis, we identified three key components critical for efficient spike palmitoylation: (i) Lys1211 at the ectodomain–transmembrane domain (TMD) interface, likely facilitating electrostatic interactions with DHHC20's acidic residues; (ii) a stable trimeric TMD helix, where mutations at the trimer interface impair palmitoylation, in contrast to changes in outward‐facing residues; and (iii) a conserved hydrophilic motif in the CT, located between acylated cysteine clusters, likely promoting optimal substrate positioning near DHHC20's catalytic site. Co‐immunoprecipitation assays revealed that mutations in these residues disrupt spike‐DHHC20 interactions, while leaving spike–DHHC9 binding unchanged, suggesting that they affect enzyme‐substrate complex formation. Fusion assays revealed nuanced effects; while palmitoylation generally correlated positively with membrane fusion, certain exceptions highlighted the complex relationship between these processes. Mutations in the CT markedly reduce total spike palmitoylation but only modestly affect cell–cell fusion. Some substitutions in the TMD impair fusion with little change in overall acylation. Our findings elucidate the structural and biophysical determinants of spike palmitoylation and its distinct roles in membrane fusion, offering insights into SARS‐CoV‐2 pathogenesis and potential antiviral targets.

Antigen-enriched tumor vaccines represent a promising strategy for cancer immunotherapy. Nevertheless, their clinical efficacy is often limited by insufficient antigen presentation and low immunogenicity. Here, a novel nanovaccine was developed that synergistically combines mitochondrial fission inhibition, tumor-dendritic cell fusion, and metal-phenolic nanoparticle technology. Tumor cells were pretreated with the mitochondrial fission inhibitor Mdivi‑1, yielding antigen‑enriched cell membranes (CM(M)). Subsequently, these CM(M) were fused with the dendritic cell membranes (DCM) overexpressing B7 biomolecules to create a tumor-dendritic cell fusion membrane (DCCM(M)). R848-loaded metal-phenolic nanoparticles (TF/R848) were further coated with the fusion membrane to create a dual-functional nanovaccine (TF/R848@DCCM(M)). This nanovaccine increases immunogenicity and optimizes antigen presentation. The nanovaccine promotes dual T-cell activation via direct antigen presentation and DC-mediated cross-presentation. TF/R848@DCCM(M) showed remarkable anticancer activity in melanoma-bearing mouse models, greatly reducing tumor development and extending longevity. Moreover, the nanovaccine enhanced the effects of immune checkpoint inhibitors, offering a promising strategy for combination immunotherapy. This study presents a novel, efficient platform for cancer immunotherapy, positioning a versatile and powerful approach for next-generation tumor vaccines.