Biology subjects

Suzuki, M.

Publications and source records attributed to Suzuki, M..

At least 19 recordsLinked to original sources

bioRxiv2026

CLOSING THE CONFORMATIONAL CYCLE OF THE BETA-BARREL ASSEMBLY MACHINERY

The {beta}-barrel assembly machinery (BAM) catalyzes the folding and insertion of {beta}-barrel outer membrane proteins (OMPs) in Gram-negative bacteria without an external energy source. BAM comprises the central subunit BamA and associated lipoproteins, with BamA forming a conformationally dynamic lateral gate. Although substrate-engaged structures have revealed key steps in OMP assembly, how substrate-free BamA closes its lateral gate and which conformations it adopts in a lipid bilayer remain unclear. Here, we determined cryo-EM structures of the Escherichia coli (E. coli) BAM complex in three detergents and in Saposin A nanodiscs composed of E. coli polar lipids. In addition to the canonical outward-open (OO) state, we identified an occluded (OC) state in which both the lateral gate and the periplasmic opening of the BamA barrel are closed. OC predominated in lipid-reconstituted BAM that retained OMP-folding activity, indicating that this state is substantially populated in a functional BAM ensemble within a lipid bilayer. We also identified a semi-occluded (sOC) state in which {beta}1-{beta}2 adopts an OC-like closed position while rearrangement of {beta}16 remains incomplete. Comparison of OO, sOC, and OC reveals asynchronous rearrangements of the {beta}1-{beta}2 and {beta}16 regions, with {beta}1-{beta}2 movement occurring without complete repositioning of {beta}16. Re-examination of previously reported lipid-embedded BAM structures further highlights the importance of local map quality at the gate region for conformational assignment. Together, our findings expand the BamA conformational landscape beyond the conventional OO-inward-open (IO) framework to include OC and sOC as distinct structural states associated with lateral-gate closure following OMP insertion.

molecular biology↗

bioRxiv2026

HPV-Associated Tonsillar Intraepithelial Neoplasia and Oral High-Risk HPV mRNA as a Candidate Biomarker

Early detection of human papillomavirus (HPV)-associated oropharyngeal cancer is an unmet need, as its premalignant lesions remain unestablished. We hypothesized that such lesions exist in individuals with oral high-risk HPV (HR-HPV) mRNA. We preoperatively screened 1,180 individuals undergoing tonsillectomy due to benign conditions and detected five with oral HR-HPV mRNA. Serial sectioning of the entire excised tonsils identified HPV-associated intraepithelial lesions in three of these five individuals. A similar lesion was identified in an additional individual with oral HPV16 infection with unknown oral HR-HPV mRNA status. Intraepithelial lesions in two individuals were HPV16-associated and showed moderate-to-severe atypia, whereas those in the other two individuals were associated with other HR-HPV and showed minimal-to-mild atypia. Based on HPV life cycle, the former were classified as transforming lesions and the latter as productive-to-intermediate lesions. Spatial transcriptomic analysis revealed molecular profiles intermediate between those of normal epithelium and HPV-associated oropharyngeal cancer. These findings establish the first evidence for HPV-associated tonsillar premalignant lesions and suggest oral HR-HPV mRNA as a candidate biomarker.

cancer biology↗

bioRxiv2026

Change-point oddball elicits pupil-linked signatures of Bayesian belief updating

The auditory oddball protocol is widely used to study neural responses to unexpected events. In conventional designs, however, stimulus statistics are stationary: deviants do not indicate environmental change and therefore should not drive learning. Here, we introduce change-point oddball, a passive, no-report protocol in which the standard-oddball mapping reverses at unpredictable change points, requiring inference over latent environmental states. We measured pupil-linked arousal in three human cohorts. Pupil responses were larger for state-specific oddballs than standards, decayed across newly established standards after state changes, and scaled with model-derived change-point probability. A many-standards control experiment implicated a prediction-based rather than repetition-based mechanism. Finally, within participants, stronger pupil encoding of change-point probability during the passive task was associated with greater change-point-sensitive belief updating in a separate active navigation task. Thus, passive change-point oddball preserves core signatures of adaptive belief updating, enabling cross-species and clinical investigations.

neuroscience↗

bioRxiv2026

Selective binocular integration in mouse visual cortex: binocular but not monocular neurons respond distinctly to congruent stimuli

Even though binocular integration is a foremost example of integrative computations in the brain, it remains unknown how the visual cortex mediates it. Here, we investigated neuronal responses to binocular stimuli in layers 2/3 of mouse primary visual cortex (V1) and lateromedial (LM) area with in vivo two-photon imaging. We presented mice with three types of binocular stimuli: congruent gratings, orthogonal gratings and a flashing Mondrian pattern in binocular conflict with a grating. We looked for congruency-specific responses to the binocular stimuli, but found that most neurons responded homogeneously across stimulus types. Responses of cells with a strong monocular preference for the contralateral eye responded similarly to monocular and binocular stimulation, while responses of cells with a preference for ipsilateral stimuli showed a strong but nonspecific suppression to all binocular stimuli. Only cells without a strong monocular preference (i.e. binocular cells) exhibited linear integration of monocular responses to incongruent stimuli and binocular facilitation to congruent gratings. Responses to ipsilateral components of a binocular display were found to be poor predictors of binocular responses regardless of eye preference of individual cells. We conclude that most neuronal responses to binocular stimuli in mouse V1 & LM are uninformative about the congruency of the monocular components, with the exception of binocular cells which show either linear or supralinear integration.

neuroscience↗

bioRxiv2026

Core genome MLST reveals genetic and BafA-associated phenotypic diversities in Bartonella henselae strains

Bartonella henselae is a zoonotic pathogen associated with cat-scratch disease. Although multilocus sequence typing (MLST) has been used for strain classification, its resolution for distinguishing between B. henselae isolates remains limited. We herein developed a B. henselae-specific core genome MLST (cgMLST) scheme based on whole-genome sequencing data and examined the genetic and phenotypic diversities of 80 strains derived from cats, humans, mongooses, and masked palm civets. Using the conventional MLST scheme, the 80 strains were classified into nine sequence types (STs), while cgMLST subdivided them into 72 cgSTs, demonstrating a marked improvement in discriminatory power. The cgMLST scheme comprised 1,183 core genes and showed high applicability across the 80 strains. A phylogenetic analysis revealed that ST1, which has been associated with cat-scratch disease, was further subdivided into three major clusters and two singletons, indicating high genetic heterogeneity within this ST. We also found that the bafA subtypes clustered in a manner that was largely consistent with the cgMLST-based phylogenetic structure, suggesting a close relationship between bafA variations and the genomic background of B. henselae strains. In a human umbilical vein endothelial cell proliferation assay, strains belonging to distinct cgSTs exhibited strain-dependent differences in proliferative capacity, which were associated with the bafA subtype classification. Some strains induced focal cell fragmentation and a reduced cell density at a high multiplicity of infection, indicating strain-dependent differences in endothelial cell injury. Collectively, the present results establish a high-resolution cgMLST framework for B. henselae and demonstrate that genetically distinct strains have diverse endothelial cell phenotypes.

microbiology↗

bioRxiv2026

Identification of a transient receptor potential channel that is regulated by phospholipid asymmetry

AbstractPhospholipid asymmetry is a hallmark of mammalian cell membranes and reflects the selective distribution of distinct phospholipid species between the two leaflets of the lipid bilayer. Although this asymmetry is tightly maintained, the membrane proteins whose functions depend on it remain largely unknown. To perturb phospholipid asymmetry experimentally, we expressed a constitutively active phospholipid scramblase and thereby identified transient receptor potential melastatin 8 (TRPM8) as an ion channel regulated by this membrane property. Activation of TRPM8 by both l-menthol and innocuous cold was markedly suppressed following disruption of phospholipid asymmetry. Likewise, selective depletion of phosphatidylserine (PS), a phospholipid enriched in the cytoplasmic leaflet, using a cytosolically targeted PS decarboxylase attenuated TRPM8 activation, indicating that cytoplasmic PS is required for proper TRPM8 function. Mechanistically, our findings suggest that cytoplasmic PS supports efficient TRPM8 activation by maintaining the biochemical state of the channel. Together, these findings identify TRPM8 as a phospholipid asymmetry-dependent ion channel and establish an experimental strategy for systematically identifying membrane proteins regulated by phospholipid asymmetry. This work provides a foundation for future studies investigating the biological significance of this fundamental membrane property.

biochemistry↗

bioRxiv2026

Sequential intra-articular HCAd-NFκB-IL-1Ra delivery improves therapeutic efficacy in post-traumatic osteoarthritis

Osteoarthritis is the most common joint disease for which disease-modifying therapies remain unavailable. Intra-articular gene delivery of interleukin-1 receptor antagonist (IL-1Ra) using high-capacity adenovirus (HCAd) has shown therapeutic promise; however, the duration of therapeutic benefit and the feasibility of repeat dosing under anti-adenoviral immunity remain unresolved. Using the murine anterior cruciate ligament transection model of osteoarthritis, we show that a single intraarticular injection of HCAd5-NF{kappa}B-IL-1Ra provides structural preservation and functional improvement in early-stage osteoarthritis but fails to sustain cartilage protection as disease progresses. However, HCAd5 transduction following repeated treatment is limited due to pre-existing immunity against this serotype. Notably, exchanging serotypes for repeated treatments effectively restores vector transduction and transgene expression in both healthy and osteoarthritic joints. Leveraging this strategy, we demonstrate that sequential intra-articular HCAd-NF{kappa}B-IL-1Ra administration does not further improve pain or motor function compared to the initial treatment, but preserves cartilage as assessed by histopathology and phase-contrast CT, irrespective of serotype. These findings establish HCAd serotype switching as a feasible approach to overcome immune barriers to repeat intra-articular gene therapy. Importantly, sequential HCAd-NF{kappa}B-IL-1Ra administration enhances therapeutic durability in post-traumatic osteoarthritis, providing a translational framework for repeat intra-articular gene delivery strategies aimed at long-term disease modification in osteoarthritis.

molecular biology↗

bioRxiv2026

Cross-Species Efficacy of Combinatorial Gene Therapy for Osteoarthritis and Correction of Neuro-Inflammatory Pain Mechanisms

Osteoarthritis is a leading cause of chronic pain and disability, which lacks disease-modifying treatment. Given the complex multi-tissue and multifactorial drivers behind disease progression, effective treatments will require simultaneously targeting several mechanisms underlying joint degeneration and pain. Here, we developed and evaluated a combinatorial gene therapy, consisting of a high-capacity adenoviral vector carrying two therapeutic genes to target distinct pathological mechanisms: inflammation (IL-1Ra) and chondrocyte health (PRG4). Intra-articular delivery of this treatment improved functional, structural, and pain outcomes in murine and equine osteoarthritis models. In addition, treatment normalized inflammatory environments in joint tissues, as well as in the dorsal root ganglia (DRG) known to harbor joint-innervating sensory neurons. Moreover, gene therapy reversed OA-induced molecular signatures of neural hyperexcitability, suggesting amelioration of peripheral sensitization. Collectively, these findings support combinatorial gene therapy as a promising treatment for osteoarthritis, while identifying neuroinflammatory signatures for correction of disease progression and pain. One Sentence SummaryA single intra-articular injection of a combinatorial gene therapy slows OA progression and reduces pain in small and large animal models.

systems biology↗

bioRxiv2026

MLL3 adaptor function, not methyltransferase catalytic activity, is essential for breast tumor suppression

MLL3 (Mixed-Lineage Leukemia 3), also known as KMT2C, is one of the most frequently altered epigenetic regulators in breast cancer. MLL3 loss-of-function leads to accelerated tumor onset and growth and increased metastasis. As a large multi-domain protein, MLL3 functions as a histone methyltransferase and a nuclear protein adaptor interacting with other epigenetic proteins. Since breast cancer MLL3 mutations are often truncating mutations that lead to protein degradation, whether the MLL3 tumor suppressor activity depends on its catalytic activity or non-catalytic chromatin adaptor function remains unclear. Here, using CRISPR genetically engineered mouse mammary stem cell organoid-based breast tumor models, we dissected dosage-dependent and domain-specific functions of MLL3 in breast tumor suppression. MLL3 heterozygous loss breast tumor models revealed that MLL3 is haplo-insufficient for breast tumor suppression. Interestingly, homozygous catalytic-dead MLL3-Y4792A mutation did not accelerate tumor onset, growth, or metastasis. By contrast, G367V mutation in the PHD2 domain, which disrupts the BAP1 complex binding without affecting MLL3 protein stability, accelerated tumor onset and growth, phenocopying MLL3 loss. Mechanistically, MLL3 loss impaired chromatin localization of UTX, and genetic depletion of UTX accelerated breast tumor progression in MLL3-wildtype but not MLL3-deficient cells. Integrated RNA-seq, CUT&TAG, and ATAC-seq analyses further showed that transcriptional changes induced by MLL3 loss were more closely associated with promoter-proximal alterations in H3K27Ac, H3K27me3, and chromatin accessibility than with putative MLL3-dependent enhancer regions. Together, these findings reveal that MLL3 suppresses breast tumor initiation through a dosage-sensitive, catalytic-independent adaptor function that regulates promoter-proximal epigenetic states.

cancer biology↗

bioRxiv2026

Cold-induced hepatic metabolic change links gluconeogenesis, lipid remodeling, and redox regulation in Xenopus laevis

BackgroundEctothermic vertebrates exhibit substantial physiological plasticity in response to environmental temperature fluctuations. Among them, amphibians show particularly pronounced metabolic adjustments under cold conditions; however, the molecular mechanisms by which the liver adapts to low temperatures remain poorly understood. To address this gap, we investigated the hepatic transcriptional response to cold exposure in the African clawed frog (Xenopus laevis) using RNA sequencing (RNA-seq) and quantitative PCR. ResultsExposure to 5{degrees}C for five days in X. laevis resulted in pronounced hyperglycemia and extensive transcriptional reprogramming in the liver. RNA-seq analysis indicated that, relative to frogs maintained at 24{degrees}C, 2,392 genes were upregulated, whereas 2,031 genes were downregulated. Notably, genes associated with gluconeogenesis, such as foxo1, g6pc1, and pck1, exhibited significant upregulation, whereas genes related to glycolysis and glucose utilization, including gck, pfkm, and ldhb, were downregulated. Concurrently, cold exposure induced the expression of genes involved in fatty acid synthesis, desaturation, and cholesterol biosynthesis, such as srebf1, acaca, fasn, scd, fads2, srebf2, and hmgcr. Conversely, genes related to fatty acid {beta}-oxidation, including ppara, cpt1a, cpt1b, slc25a20, acadl, hadha, and hadhb, were significantly suppressed. In alignment with this pattern, multiple components of the mitochondrial electron transport chain and ATP synthesis machinery were also downregulated. Additionally, gene groups involved in antioxidant defenses, such as gpx4, gpx1, prdx2, prdx5, prdx6, and ferritin-related genes, were upregulated. Representative transcriptomic changes were validated using quantitative PCR analysis. ConclusionsExposure to cold temperatures induced coordinated metabolic reprogramming in the liver of X. laevis. This reprogramming was characterized by the activation of gluconeogenesis, suppression of glycolysis, fatty acid {beta}-oxidation, and oxidative phosphorylation, and induction of lipid and cholesterol biosynthetic pathways. These metabolic adjustments suggest that frogs acclimated to cold conditions adopt an energy-conserving metabolic strategy while sustaining glucose production and promoting lipid remodeling to adapt to low-temperature environments. These findings offer novel insights into the molecular mechanisms underlying cold adaptation in ectothermic vertebrates and underscore the pivotal role of the liver in managing transcriptional responses to cold stress.

physiology↗

bioRxiv2026

Wnt signaling and tissue tension reconstitute planar cell polarity in vitro

Planar cell polarity (PCP) aligns cells within the plane of a tissue through asymmetric localization of core PCP proteins. In vivo, PCP arises from integration of biochemical signaling and mechanical inputs, making it challendging to reconstruct in vitro. Here we reconstitute PCP in cultured MDCK epithelial cells using Wnt signaling, collective migration, and Prickle3 overexpression. Loss of Vangl1 disrupts reconstituted PCP, directional collective migration, and propagation of ERK traveling waves. Orthogonal manipulation of signaling and mechanics show that tissue tension contributes to establishing a polarity axis, but not its direction, whereas local Wnt input specifies polarity direction. Together, these inputs generate tissue-wide vectorial polarity. This system provides a tractable framework for dissecting how signaling and mechanics are integrated to organize tissues. TeaserWnt signaling and tissue tension reconstitute planar cell polarity in cultured epithelial cells through core-component interdependence and ERK dynamics.

synthetic biology↗

bioRxiv2026

Visualization of peripheral nerves in developing and regenerating limbs using a novel peripherin reporter line of Xenopus laevis

Peripherin (PRPH) is a class III intermediate filament protein expressed in peripheral nerves and upregulated during axon outgrowth and regeneration. In this study, we developed a transgenic Xenopus laevis line for long-term in vivo visualization of the peripheral nervous system. Deletion and motif analyses identified cis-regulatory regions within the promoter and intron 1 that are important for neuronal expression of the X. laevis prph gene. Stable lines exhibited robust EGFP reporter activity in developing neural primordia in embryos and in the peripheral nerves of tadpoles. Transgenic tadpoles enabled in vivo imaging of peripheral nerves throughout limb development. During larval limb regeneration, we observed modest early nerve entry into the blastema, recapitulating that seen in early limb development. In contrast, post-metamorphic limb blastemas displayed extensive innervation from the early phase of regeneration. Moreover, increased reporter activity in the nerves of the regenerating adult forelimb suggests regeneration-associated regulation of peripheral innervation and its potential role in blastema formation. This transgenic line will serve as a versatile tool for analyzing such large-scale neural remodeling across development, metamorphosis, and regeneration.

developmental biology↗

bioRxiv2026

Transcriptomic timeseries links hepatic gene expression to an early and self-limited systemic response to enteric infection

The liver receives microbe and host signals from the intestine via the portal vein, thereby connecting the gut to systemic physiology. Homeostatic control of the timing of systemic responses is critical to prevent the expansion and dissemination of gut microbes and to mitigate untoward effects from prolonged systemic inflammation, however these mechanisms remain enigmatic. Here, to determine the role of the liver in coordinating systemic immune responses to enteric infection, matched measurements of global gene expression profiles were collected from the murine liver and intestinal epithelium throughout the course of enteric infection and clearance of Citrobacter rodentium, a mouse model of infectious colitis. These data revealed metabolic suppression in the liver during the peak of infection and a long-lived immune signaling pattern in the colon associated with CD4 and CD8 T cell infiltration that persisted beyond the clearance of infection. Furthermore, an early inflammatory signal was detected in the liver that resolved before the peak of disease and pathogen colonization. This self-limited, early signal depended on the pathogens virulence program and correlated with the timing of a corresponding systemic response, including circulating TNF- and IL-6, key mediators of acute-phase proteins. These results uncover the temporal pattern of hepatic changes in response to the course of intestinal infection and provide correlative evidence that an early pulse of gene expression in the liver coordinates and limits the duration of the systemic acute-phase protein response. Author summaryLocalized infections can trigger systemic inflammatory responses that help limit infection. However, prolonged systemic inflammation risks tissue damage and disease. Thus, the timing of systemic immune reactions is critical to the balance between immunity and damage. Yet, knowledge of the pathways that link gut-localized infections to systemic immune tone is limited. Since the liver is anatomically central to the connection between the gut and circulatory systems, we hypothesized that monitoring the kinetics of liver gene expression throughout the natural course of an intestinal bacterial infection would provide a valuable resource and yield insight into the control of systemic immune tone. Critically, we identified a burst of liver cytokine signaling that occurred and resolved before peak pathogen burden and disease in the colon and predicted the circulating inflammatory response. We propose that this early and self-limited signal from the liver coordinates the timing of the systemic response, ensuring it occurs early enough to promote immunity and resolve before causing tissue damage.

immunology↗

bioRxiv2026

VicMAG, an open-source tool for visualizing circular metagenome-assembled genomes highlighting bacterial virulence and antimicrobial resistance

Bacterial pathogens spread in clinical and environmental settings, and mobile genetic elements (MGEs), such as plasmids and phages, mediate the transfer of virulence factor genes (VFGs) and antimicrobial resistance genes (ARGs) among bacterial communities. Metagenomic analysis of environmental and wastewater samples using highly accurate long-read sequencing technologies, such as PacBio HiFi sequencing, provides valuable insights into monitoring the regional spread of VFGs and ARGs, including dissemination mediated by MGEs. No visualization tool is currently available for the comprehensive display of numerous resulting circular metagenome-assembled genomes (cMAGs) with functional gene annotations. Here, we developed VicMAG, a visualization tool for highly complex cMAGs derived from long-read metagenome assemblies annotated using updated databases of VFGs, ARGs, and MGEs. Using 353 cMAGs from PacBio HiFi sequencing of a wastewater sample, we demonstrated the utility of VicMAG for metagenome visualization. VicMAG provides comprehensive, size-aware visualization of cMAGs representing bacterial chromosomes and plasmids, annotated with VFGs, ARGs, and phages. By simultaneously visualizing all cMAGs in a framework, VicMAG facilitates a holistic understanding of the distribution and genomic context of VFGs and ARGs across complex microbial communities. This tool supports integrated surveillance of bacteria associated with virulence and antimicrobial resistance across clinical, environmental, and One Health contexts.

bioinformatics↗

bioRxiv2026

Tracing the emergence of the novel fluoroquinolone resistance gene qrtA in enterococci through environmental reservoirs and pELF-type linear plasmids

As animal hosts adapted to land, Enterococcus species diverged from a common ancestor shared with Vagococcus species by acquiring genes essential for survival and transmission in the exposed arid environment. In addition to their intrinsic ruggedness, human-associated enterococci now frequently exhibit multidrug resistance, largely driven by the accumulation of antimicrobial resistance genes (ARGs) on mobile genetic elements (MGEs). However, the source of these resistance elements, their diversity in natural reservoirs, and the risk that they pose remain unclear. To investigate the movement of novel ARGs from the environmental reservoir and the elements that convey them into clinically important enterococcal lineages, we examined environmental vancomycin-resistant enterococci (VRE) circulating in a polluted urban river in Hanoi, Vietnam. Whole-genome sequencing of VRE isolates revealed multidrug-resistance pELF-type linear plasmids harboring a novel fluoroquinolone resistance gene (qrtA) encoding a major facilitator superfamily transporter. The qrtA gene appears to have originated on Vagococcus chromosomes and to have been mobilized by IS1216E-associated MGEs. Vagococcus genomes show strong associations between ARGs, IS1216E, and plasmids related to those in enterococci, and conjugation experiments demonstrated that pELF-type linear plasmids can transfer between Enterococcus and Vagococcus without major fitness costs, positioning them as plausible vehicles for importing environmental ARGs into enterococci. Reconstruction of pELF-type linear plasmid evolution in the environment, together with database mining of rare qrtA-positive clinical isolates from Asia and Europe, suggests that qrtA-bearing pELF-type linear plasmids are in an early phase of global dissemination. These findings highlight the need for coordinated international One Health surveillance of ARG and MGE dynamics, including emerging determinants such as qrtA, together with proactive interventions to limit their spread.

microbiology↗

bioRxiv2026

Divergent mechanics of inner ear morphogenesis are coupled to developmental tempo over vertebrate evolution

Vertebrate embryos vary in size and developmental tempo based on reproductive strategies; however, organs of ancient origin, such as the eye and inner ear, remain highly conserved in structure and function. How both diverse embryonic traits and conserved organ development occur remains unclear. Here, we identify divergent morphogenetic mechanics of inner ear development, particularly in vesicular primordium expansion, in 12 species representing the major vertebrate lineages. Differences in cell volume regulation determine tissue growth mechanics, which diversify the expansion process but yield a conserved morphological outcome. Heterochronic shifts in organogenesis allow this regulation to evolve in coordination with a prolonged developmental period. These findings suggest that alternative morphogenetic mechanics mitigate the effects of diversified embryonic traits, thereby ensuring consistent morphological outcomes for highly conserved organs.

evolutionary biology↗

bioRxiv2026

Transregional astrocyte-dependent metaplasticity in the hippocampus

Learning-related synaptic plasticity is regulated by metaplasticity, which adjusts plasticity thresholds in an activity-dependent manner. We have previously described a heterodendritic form of metaplasticity whereby priming stimulation in stratum oriens (SO) inhibits subsequent long-term potentiation (LTP) in the neighboring stratum radiatum of the hippocampal CA1 region. Here, we report that this metaplasticity is, in fact, transregional, in that the SO priming stimulation also inhibits later LTP induction at dentate gyrus (DG) middle molecular layer (MML) synapses, both in vitro and in vivo. This effect operates across the hippocampal fissure since it occurs in the absence of CA3, thus highlighting a previously unappreciated reverse-direction and long-distance hippocampal crosstalk. Our findings demonstrate an essential role of astrocytes as SO priming elicited a sustained increase in the frequency of calcium (Ca2+) events in astrocytes in the DG MML, while the metaplasticity effect was blocked by calcium-buffering in MML astrocytes. It could be triggered by either activation of M1 muscarinic acetylcholine receptors or group II metabotropic glutamate receptors, and was critically dependent on inositol 1,4,5-trisphosphate receptor type 2 signaling. The transregional inhibition of LTP was mediated by astrocytic release of tumor necrosis factor (TNF), which likely acts in an autocrine fashion on astrocytic TNF type 1 receptors (TNFR1s). Downstream of TNF-TNFR1 signaling, the inhibition of MML LTP was mediated by the activation of GluN2B-containing N-methyl-D-aspartate receptors. Thus, a complex, bidirectional neuron-glia signaling cascade orchestrates long-distance metaplasticity across hippocampal subregions, providing a novel framework for understanding how hippocampal neuronal networks dynamically regulate plasticity thresholds across space and time. Significance StatementThis study documents the existence of a transregional metaplasticity that traverses from area CA1 to the dentate gyrus across the hippocampal fissure. This reveals a novel long-distance crosstalk within the hippocampus, in addition to the classical pathways of information transfer. This form of metaplasticity entails an essential contribution by astrocytes that integrate neuronal activity and use a complex Ca2+-dependent neuron-glia-neuron signaling cascade to dynamically regulate LTP thresholds in the hippocampal dentate gyrus.

neuroscience↗

bioRxiv2026

Atomistic simulation study reveals transduction of mechanical work generated by ATP hydrolysis onto myosin II functional loops

Myosin II is a paradigm of biological molecular energy transducers that convert the chemical energy of ATP, via hydrolysis, into mechanical work with high efficiency in living cells. The physicochemical mechanisms underlying energy conversion by myosin II have been extensively investigated. However, a remaining challenge concerns the initial stage of the ATP hydrolysis cycle, specifically the conversion of ATP-to-ADP:Pi, because of technical difficulties in directly and seamlessly observing atomic trajectories during this early step and the subsequent processes. Here, we simulate the consequences of the chemical reaction by switching force field parameters between reactant and product systems within classical molecular dynamics simulations. We consider two possible ATP hydrolysis mechanisms in which either singly protonated (Pi{superscript 2}-) or doubly protonated (Pi-) inorganic phosphate is produced. Our results indicate that, in both Pi-generating processes, the kinetic energy supplied by conversion of ATP-to-ADP:Pi increases only transiently, whereas myosin functional loops store several kcal/mol of potential energy. Meanwhile, the amount of potential energy stored in the Pi{superscript 2}--producing reaction is approximately five-fold larger than that in the Pi--producing reaction. Our analysis indicates that this difference emerges when ATP-derived mechanical work is transmitted into the functional loops via rearrangement of intermolecular hydrogen bonds with the hydrolysis products. Notably, these steric interactions remain stably established even when the kinetic energy input associated with ATP-to-ADP:Pi conversion is actively quenched. We therefore propose that transient storage of ATP-derived mechanical work as atomic-scale conformational strain within myosin molecules constitutes a critical step for efficient conversion of ATP chemical energy into mechanical work under conditions of intracellular thermal noise. SignificanceMyosin II converts chemical energy released by ATP hydrolysis into mechanical work with exceptionally high efficiency, even in the presence of substantial thermal fluctuations in living systems. It has long been proposed that release of inorganic phosphate (Pi) from myosin II is a critical step for efficient energy transfer. However, this prevailing view has been challenged by recent state-of-the-art experimental observations, necessitating a reexamination of the chemical steps responsible for ATP-derived energy storage. Here, we employ atomistic molecular dynamics simulations specifically designed to capture key aspects of ATP hydrolysis. We demonstrate that ATP hydrolysis increases the potential energy of myosin II functional loops while Pi remains bound, and that this increase occurs independently of heat release associated with the reaction. Together, these findings identify an alternative mechanism for energy retention and emphasize the intrinsic robustness of myosin II as a highly efficient molecular motor.

biophysics↗