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Biology subjects

Zhai, H.

Publications and source records attributed to Zhai, H..

At least 19 recordsLinked to original sources

Pyruvate partitioning defines an immunosuppressive metabolic niche in colorectal cancer

Purpose. Colorectal cancer (CRC) reprograms glucose metabolism, diverting pyruvate from mitochondrial oxidation toward lactate export. How this partitioning decision is organized across cell types and tissue space, and how it relates to immune programmes, remains unresolved. Methods. We defined a Pyruvate Partitioning Index (PPI) as the difference between an oxidative arm (MPC1, MPC2, PDHA1, PDHB, DLAT, DLD, PDHX) and an export arm (LDHA, LDHB, SLC16A1, SLC16A3, SLC16A7), and computed it across TCGA COADREAD (n = 592), GSE39582 (n = 579), two single-cell atlases (370,115 and 63,689 cells), 13 Visium sections and an exploratory urothelial immunotherapy cohort (IMvigor210, n = 298). Results. PPI was lowest in microsatellite-unstable (MSI) tumours (Mann-Whitney p = 3.8 x 10^-9) and inversely associated with overall survival (log-rank p = 1.2 x 10^-4). Epithelial cells were the most oxidative compartment (median +0.058) and myeloid cells the most export-prone (-0.171; Kruskal p [~] 0), reproduced independently; MMRd epithelium was intrinsically export-shifted (-0.012 vs +0.076 vs +0.192 for MMRd, MMRp and normal). Spatially, PPI was non-random (Moran's I significant in 12/13 sections), with low-PPI spots enriched for SPP1+ macrophages, myofibroblasts and plasma cells, but not CD8+ T-cell factors. Low-PPI tumours showed coordinated increases in immune-checkpoint, myeloid and Treg programmes (checkpoint rho = -0.262), and network perturbation identified LDHA as the hub. Conclusions. Pyruvate partitioning is cellularly and spatially organized in CRC and defines a myeloid-stromal immunosuppressive niche. Because MSI tumours (the best CRC immunotherapy responders) had the lowest PPI, the PPI-response relationship appears cancer-type specific and requires validation in CRC cohorts.

cancer biology↗

Human Cytomegalovirus Infects and Remodels 3D-biofabricated Skin Equivalents

Viral infection, including for the prototypical betaherpesvirus human cytomegalovirus (HCMV) is typically studied in two-dimensional monocultures, which provide experimentally tractable systems for measuring viral replication but do not reproduce the biologically accurate multicellular organization or interactions, nor the three-dimensional (3D) architecture of stratified epithelial tissues. Here, we evaluated a biofabricated 3D skin model containing fibroblasts and keratinocytes as a system to study HCMV infection. The model is generated using a fibrin-based matrix and spatially organization deposition of keratinocytes in combination with fibroblasts, followed by cellular differentiation controlled by calcium conditions. Cultures were infected with a GFP-expressing clinical strain of HCMV (TB40/E-GFP) and compared to traditional monolayer cultures or single cell type 3D cultures. HCMV infection was detectable by GFP expression in an MOI-dependent and longitudinal manner. Infectious virus was recovered from both the cellular associated and released into the extracellular space of the model, demonstrating that the model supports productive viral infection. Transit of infectious virus is reduced in both multicellular and single type 3D cultures, suggesting that the matrix composition influences viral kinetics. Treatment with the antiviral Ganciclovir suppressed virus production in both fibroblast monolayer cultures and 3D skin cultures. These findings establish a tractable, longitudinal observable, multicellular 3D system that supports productive HCMV infection and provides a reliable platform for investigating viral replication in a spatially organized tissue context.

microbiology↗

Architectural trade-offs between environmental stability and genomic redundancy reveal divergent pneumoviral entry strategies

Human respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) exhibit distinct seasonal epidemiology, with RSV circulating in early autumn and hMPV peaking in midwinter, yet the structural basis for this niche partitioning remains undefined. Here, we integrate in situ cryo-electron tomography and functional virology to decode the architectural logic governing their entry dynamics. RSV employs a matrix (M)-regulated prefusion F (pre-F) organization, partitioning trimers into stabilizing hexagonal superlattices and fusion-competent pools to maintain superior thermotolerance. By contrast, hMPV compensates for its intrinsically unstable, monomeric pre-F with extreme ribonucleoprotein polyploidy, packaging [~]4-fold more genome equivalents to ensure productive infection. Fusion events localize exclusively to M-depleted, non-arrayed membrane regions, establishing a spatial checkpoint for activation. These findings reveal a conserved trade-off between environmental resilience and genomic redundancy that dictates divergent pneumoviral entry strategies, explaining their distinct seasonal ecological niches.

microbiology↗

A hierarchical activation threshold shapes RSV F antibody repertoires from toddler vulnerability to adult protection

Respiratory syncytial virus (RSV) causes severe infant morbidity, yet the mechanisms underlying their suboptimal immunity and the failure of prefusion F-stabilized adult vaccines in infants remain unclear. Here we integrate deep mutational scanning of 761 preF-binding antibodies, repertoire profiling of 102 repeatedly exposed pediatricians and 61 RSV-experienced toddlers, structural analysis, and >40,000 viral genomes to decode RSV F immunity. We resolved 12 immunologically distinct functional antibody subclasses and uncovered a hierarchical activation threshold: apical epitope-targeting antibodies with superior neutralizing potency demand extensive somatic hypermutation and cooperative CDR networks, whereas central-to-basal epitope-directed, marginal or non-neutralizing antibodies engage germline-encoded antibodies through minimal mutations (e.g., S31G). Toddler repertoires are confined to low-threshold, non-productive sites; adult repertoires enrich for apical elite neutralizers whose immune pressure drives contemporary RSV-B evolution. These reframe pediatric RSV vulnerability as a threshold-gated repertoire deficit and prescribe vaccine strategies that actively redirect immunodominance from permissive epitopes toward high-barrier apical targets.

immunology↗

Rational antigen engineering and mucosal delivery design for next-generation RSV vaccines

Respiratory syncytial virus (RSV) prefusion F (preF) vaccines have transformed adult prophylaxis, yet unmet needs in antigen stability, pediatric safety, and mucosal protection persist. Here, we develop an integrated structure-guided RSV vaccine design platform that couples allosteric stabilization, epitope-focused immunogen engineering, and route-specific mRNA delivery for systemic and mucosal immune activations. By mapping prefusion F "breathing" motions and applying a ThermoNet-and Rosetta-guided screening funnel, we identified R296, a stabilized prefusion F immunogen that reinforces the 1-5 hinge and interprotomer interfaces while preserving key neutralizing epitopes. Cryo-EM confirmed that R296 retains a native-like prefusion architecture. And mRNA-LNP vaccination elicited potent, durable, and broadly protective neutralizing responses in mice, rats, and cotton rats, with clearance of detectable infectious virus and no evidence of Th2-skewed enhanced respiratory disease. To address pediatric safety, we designed a stalkless nanoparticle immunogen, Head38-50AB-3, which enriches high-potency apical epitopes while excluding stalk regions associated with low-potency or non-protective responses, conferring protection without VAERD-like pathology. Finally, we engineered an intranasal-delivered LNP that enables intranasal R296 mRNA delivery, inducing systemic neutralization together with robust nasal and bronchoalveolar secretory IgA (sIgA). R296 has now advanced to Phase 1 clinical trials. These results establish a modular framework for next-generation RSV vaccines.

microbiology↗

Cryo-EM structures and structure-guided design of Atlas virus capsids

Endogenous viruses and retroelements occupy a large fraction of genomes, but the properties of proteins they encode remain largely uncharted. Here, we define Atlas viruses, a new clade of endogenous viruses in nematodes with a retrovirus-like genome organization, phlebovirus-like envelope glycoproteins, and highly divergent Gag proteins. Cryo-EM structures of particles from three Atlas viruses reveal thin-shelled icosahedral assemblies containing 60, 240, 420 or 720 capsid proteins and ranging from 20 to 60 nm in diameter. The capsid fold and assembly interactions are distinct from those of orthoretroviruses but reminiscent of spumaretrovirus and dArc capsids. Atlas capsids package nucleic acids, enter cell by endocytosis, and disassemble at endolysosomal pH. Through structure-guided engineering, we generated recombinant Atlas particles with increased pH resilience and particles displaying a CTLA-4 receptor-targeting tag. This work identifies Atlas capsids as attractive candidates for development as engineerable scaffolds for tissue-specific nucleic acid delivery.

biochemistry↗

Hemodynamic Analysis of a Repaired Ascending Aorta with Preserved Aortic Root

PurposeTo evaluate the hemodynamic impact of restoring a normal sino-tubular junction (STJ) following a novel Hegar dilator-based procedure in patients undergoing root-sparing ascending thoracic aortic aneurysm (ATAA) repair using computational modeling. MethodsWe retrospectively selected an ATAA patient who underwent pre- and postoperative gated computed tomography angiography (CTA). We developed a novel workflow to segment the lumen, thick-walled aorta, and aortic valve from CTA images for subsequent blood flow analysis using computational fluid dynamics (CFD) and fluid-structure interaction (FSI). Morphological and hemodynamic characteristics of the root were quantified and compared against those of a control subject, with no noted ascending aortic dilation. The models sensitivity to graft properties and leaflet material heterogeneity was analyzed. ResultsBoth CFD and FSI results showed that the postoperative geometry reconstructed with a normal STJ profile reintroduces sinus vortices during peak systole, similar to the control subject, but were absent pre-surgery. Accounting for aortic valve leaflets in FSI studies yielded qualitatively similar results to the CFD cases, albeit with locally elevated velocities, time-averaged wall shear stress (TAWSS), and energy dissipation, likely due to the dynamically changing orifice area and differing profiles of the left ventricular outflow tract (LVOT). ConclusionWe demonstrated that the novel Hegar dilator-based STJ reconstruction restores normal blood flow patterns, highlighting the importance of reprofiling the aortic sinuses and STJ. The study also highlights the models sensitivities, particularly the LVOT shape and leaflet morphology and mobility, and may assist planning STJ reconstruction to yield optimal hemodynamics before intervention.

bioengineering↗

Multiplexed Neuromodulatory-Type-Annotated EM-Reconstruction of Larval Zebrafish

Diverse neuromodulatory systems confer functional flexibility upon the hardwired sensorimotor pathways of the brain1-6. Among these, the evolutionarily conserved locus coeruleus (LC)-norepinephrinergic (NE) system integrates and broadcasts information globally7-9. While previous studies have primarily focused on its axonal outputs and effects on neural processing, the organizational logic of its synaptic inputs, enabling it to sense global brain states and in turn shape its activity dynamics for appropriate neuromodulation10,11, remains poorly explored. To address this, we mapped the synaptic input architecture of individual LC-NE neurons by establishing Fish-X, a whole-brain microscale reconstruction of larval zebrafish with neuron-type annotations. This dataset encompasses the retina, brain and anterior spinal cord, capturing >240,000 cells and >25 million synapses. Monoaminergic (including NE, dopaminergic, and serotonergic), hypocretinergic, and glycinergic neurons were resolved by multiplexed subcellular APEX2 labeling, while glutamatergic and GABAergic identities were inferred via morphology comparison with a zebrafish mesoscopic atlas12,13. Compared with other neuronal populations, LC-NE neurons display distinct perisomatic features and high dendritic indegrees. Reconstruction of near-complete dendritic inputs to individual LC-NE neurons reveals their broad yet sparse synaptic convergence across the brain. These synaptic inputs are not randomly distributed but instead organized according to sensory/motor modality, excitatory/inhibitory identity, and synaptic strength. Individual LC-NE neurons share common inputs, a feature conserved within and across monoaminergic systems, suggesting a co-innervation mechanism for coordinated neuromodulation. Thus, our study uncovers multi-level principles governing the spatial organization of LC-NE neurons broad-yet-sparse inputs and provides a pivotal resource for deciphering the microscale architecture of neuromodulatory systems.

neuroscience↗

PIBE: Parallel ion beam etching of sections collected on wafer for ultra large-scale connectomics

We developed a parallel ion beam etching device that simultaneously thins hundreds of sections on a whole 4-inch wafer at 20 nm steps, enabling sub-centimeter volumetric imaging with high axial resolution. Compared with traditional volume electron microscopy, PIB preserves in-situ continuity within sections and simplifies inter-section registration. Its high axial resolution facilitates reliable neuron segmentation and tracing with reduced proofreading, providing an efficient route toward ultra-large-scale connectomics, such as whole-mouse-brain reconstruction.

neuroscience↗

Connectomic Organization of the Suprachiasmatic Nucleus

The suprachiasmatic nucleus (SCN), the mammalian master clock, is a special structure dedicated to the time computation. However, a connectomic understanding of the nucleus as a whole is lacking. Using serial section electron microscopy, we reconstructed multiscale and multimodal SCN communication networks. Intra-SCN synaptic network consists of 9,566 morphologically similar neurons and 4.3 million synapses, organized into multiscale circuitries that interact with SCN-traversing axon fascicles. Strikingly, SCN neurons engage in unique soma-soma ephaptic interaction, forming 2,038 electrotonic integrative units with the largest overlapping the light-responsive area (LRA). SCNs paracrine modality contains 47,396 m3 dense core vesicles, with notable scarcity in the LRA, suggesting cross-modal coordination and functional integration. These distinct network features provide comprehensive insights into the system architecture of the mammalian circadian clock.

neuroscience↗

Data-Driven Image Analysis to Determine Antibody-Induced Dissociation of Cell-Cell Adhesion and Antibody Pathogenicity in Pemphigus Vulgaris

Pemphigus vulgaris (PV) is a blistering autoimmune disease that affects the skin and mucous membranes. The precise mechanisms by which PV antibodies induce a complete loss of cohesion of keratinocytes are not fully understood. But it is accepted that the process starts with antibody binding to desmosomal targets which leads to its disassembly and subsequent structural changes to cell-cell adhesions. In vitro immunofluorescence imaging of desmosome molecules has been used to characterize this initial phase, often qualitatively. However, there remains an untapped potential of image analysis in providing us more in-depth knowledge regarding ultrastructural changes after antibody binding. Currently, there is no such effort to establish a quantitative framework from immunofluorescence images in PV pathology. We take on this effort here in a comprehensive study to examine the effects of antibodies on key adhesion molecules and the cytoskeletal network, aiming to establish a correlation of ultrastructural changes in cell-cell adhesion with antibody pathogenicity. Specifically, we introduced a data-driven approach to quantitatively evaluate perturbations in adhesion molecules, including desmoglein 3, E-cadherin, as well as the cytoskeleton, following antibody treatment. We identify distinct immunofluorescence imaging signatures that mark the impact of antibody binding on the remodeling of the adhesion molecules and introduce a pathogenicity score to compare the relative effects of different antibodies. From this analysis, we showed that the biophysical response of keratinocytes to distinct PV associated antibodies is highly specific, allowing for accurate prediction of their pathogenicity. For instance, the high pathogenicity scores of the PVIgG and AK23 antibodies show strong agreement with their reported PV pathology. Our data-driven approach offers a more detailed framework for the action of autoantibodies in pemphigus and has the potential to pave the way for the development of effective novel diagnostic methods and therapeutic strategies. SIGNIFICANCEPemphigus vulgaris (PV) presents a critical unmet medical challenge due to its autoimmune-induced disruption of skin cell adhesion. Our study presents a data-driven approach to quantitatively analyze changes in adhesion molecules and the cytoskeleton upon exposure to various PV antibodies. By introducing a pathogenicity score, we pinpoint the specific impacts of different antibodies on various proteins, build association among these antibodies, and reveal the contribution of previously overlooked non-desmosomal antibodies, broadening the understanding of PV pathology. Although centered on PV, our method offers a versatile framework applicable for evaluating the effects of other antibodies and drugs, paving the way for new diagnostic tools for personalized medicine.

biophysics↗

Selective Labeling Meets Semi-Supervised Neuron Segmentation

Semi-supervised learning offers a cost-effective approach for neuron segmentation in electron microscopy (EM) volumes. This technique leverages extensive unlabeled data to regularize supervised training for more robust predictions of neuron boundaries. However, the distribution mismatch between labeled and unlabeled data, due to limited annotations and diverse neuronal structures, can cause unreliable predictions on unlabeled data, thus limiting the generalization of semi-supervised models. In this paper, we develop a distribution-aware pipeline to address the inherent mismatch issue and enhance semi-supervised neuron segmentation in EM volumes. At the data level, we propose an unsupervised heuristic to select valuable sub-volumes as labeled data based on distribution similarity in a pretrained feature space, ensuring a representative coverage of neuronal structures. At the model level, we introduce an axial-through mixing strategy into anisotropic neuron segmentation and integrate it into a semi-supervised framework. Building on this, we establish cross-view consistency constraints through intra- and inter-mixing of labeled and unlabeled data, which facilitates the learning of shared semantics across distributions. Extensive experiments on public EM datasets from multiple species, imaging modalities, and resolutions demonstrate the effectiveness of our method. Codes and demos are available at https://github.com/yanchaoz/SL-SSNS.

neuroscience↗

Desmosomal Cadherin Tension Loss in Pemphigus Vulgaris Mediated by the Inhibition of Active RhoA at Cell-Cell Adhesions

Binding of autoantibodies to keratinocyte surface antigens, primarily desmoglein 3 (Dsg3) of the desmosomal complex, leads to the dissociation of cell-cell adhesion in the blistering disorder pemphigus vulgaris (PV). After the initial disassembly of desmosomes, cell-cell adhesions actively remodel in association with the cytoskeleton and focal adhesions. Growing evidence highlights the role of adhesion mechanics and mechanotransduction at cell-cell adhesions in this remodeling process, as their active participation may direct autoimmune pathogenicity. However, a large part of the biophysical transformations after antibody binding remains underexplored. Specifically, it is unclear how tension in desmosomes and cell-cell adhesions changes in response to antibodies, and how the altered tensional states translate to cellular responses. Here, we showed a tension loss at Dsg3 using fluorescence resonance energy transfer (FRET)-based tension sensors, a tension loss at the entire cell-cell adhesion, and a potentially compensatory increase in junctional traction force at cell-extracellular matrix adhesions after PV antibody binding. Further, our data indicate that this tension loss is mediated by the inhibition of RhoA at cell-cell contacts, and the extent of RhoA inhibition may be crucial in determining the severity of pathogenicity among different PV antibodies. More importantly, this tension loss can be partially restored by altering actomyosin based cell contractility. Collectively, these findings provide previously unattainable details in our understanding of the mechanisms that govern cell-cell interactions under physiological and autoimmune conditions, which may open the window to entirely new therapeutics aimed at restoring physiological balance to tension dynamics that regulates the maintenance of cell-cell adhesion.

biophysics↗

Mechano-regulation of GLP-1 production by Piezo1 in intestinal L cells

Glucagon-like peptide 1 (GLP-1) is a gut-derived hormone secreted by intestinal L cells and vital for postprandial glycemic control. As open-type enteroendocrine cells, whether L cells can sense mechanical stimuli caused by chyme and thus regulate GLP-1 synthesis and secretion is unexplored. Our study showed expression of Piezo1 in intestinal L cells. Its level varied in different energy status and correlates with blood glucose and GLP-1 levels. Mice with L cell-specific loss of Piezo1 (IntL-Piezo1-/-) exhibited impaired glucose tolerance, increased body weight, reduced GLP-1 production and decreased CaMKK{beta}/CaMKIV-mTORC1 signaling pathway under normal chow diet or high fed diet. Activation of the intestinal Piezo1 by its agonist Yoda1 or intestinal bead implantation increased the synthesis and secretion of GLP-1, thus alleviated glucose intolerance in diet-induced-diabetic mice. Overexpression of Piezo1, Yoda1 treatment or stretching stimulated GLP-1 production and CaMKK{beta}/CaMKIV-mTORC1 signaling pathway, which could be abolished by knockdown or blockage of Piezo1 in primary cultured mouse L cells and STC-1 cells. These findings suggest a previously undiscovered mechano-regulation of GLP-1 production in L cells, which may shed new light on the treatments of diabetes.

physiology↗

InSituCor: a toolkit for discovering non-trivial spatial correlations in spatial transcriptomics

Spatial transcriptomics presents the best kind of problem: how to find the many biological insights hidden within complex datasets. Spatially correlated genes can reveal high-interest phenomena like cell-cell interactions and latent variables. We introduce InSituCor, a toolkit for discovering modules of spatially correlated genes. A major contribution is that InSituCor returns only correlations not explainable by obvious factors like the cell type landscape; this spares precious analyst effort for non-trivial findings. InSituCor supports both unbiased discovery of whole-dataset correlations and knowledge-driven exploration of genes of interest. As a special case, it evaluates ligand-receptor pairs for spatial co-regulation.

bioinformatics↗

Tomato CYP94C1 terminates jasmonate signaling during fruit ripening by inactivating bioactive jasmonoyl-L-isoleucine

Ripe fruits are more susceptible to necrotrophic pathogens than unripe fruits. Although this phenomenon is widespread across different fruit species and results in substantial economic losses, the underlying mechanism is still poorly understood. Previous studies revealed that ethylene (ET) is a key signal controlling climacteric fruit ripening and that jasmonate (JA) regulates plant resistance to necrotrophs. We investigated the function of tomato cytochrome P450 94 (CYP94) family genes in JA signaling and report here that ET-mediated ripening suppresses JA-mediated defense by promoting the deactivation of bioactive JA-Ile. ETHYLENE-INSENSITIVE 3 (EIN3)/EIN3-LIKE (EIL) transcription factors directly activated CYP94C1 to convert JA-Ile to its inactive form 12-COOH-JA-Ile, thereby terminating JA signaling during fruit ripening. Mutation of CYP94C1 led to increased resistance of ripe fruits to the necrotrophic pathogen Botrytis cinerea without affecting the ripening process. Additionally, the master transcription factor MYC2 directly activated two other CYP94 members CYP94B1 and CYP94B2 to convert JA-Ile to its less active form 12-OH-JA-Ile, thereby attenuating JA signaling in wounded leaves. Simultaneous mutation of CYP94B1 and CYP94B2 increased the resistance of leaves to B. cinerea. Thus, differences in the expression and enzymatic activities of CYP94 family gene members precisely control JA-mediated defense responses in tomato.

plant biology↗

Haploid-resolved and chromosome-scale genome assembly in hexa-autoploid sweetpotato (Ipomoea batatas (L.) Lam)

Sweetpotato (Ipomoea batatas (L.) Lam) is the worlds seventh most important food crop by production quantity. Cultivated sweetpotato is a hexaploid (2n = 6x = 90), and its genome (B1B1B2B2B2B2) is quite complex due to polyploidy, self-incompatibility, and high heterozygosity. Here we established a haploid-resolved and chromosome-scale de novo assembly of autohexaploid sweetpotato genome sequences. Before constructing the genome, we created chromosome-scale genome sequences in I. trifida using a highly homozygous accession, Mx23Hm, with PacBio RSII and Hi-C reads. Haploid-resolved genome assembly was performed for a sweetpotato cultivar, Xushu18 by hybrid assembly with Illumina paired-end (PE) and mate-pair (MP) reads, 10X genomics reads, and PacBio RSII reads. Then, 90 chromosome-scale pseudomolecules were generated by aligning the scaffolds onto a sweetpotato linkage map. De novo assemblies were also performed for chloroplast and mitochondrial genomes in I. trifida and sweetpotato. In total, 34,386 and 175,633 genes were identified on the assembled nucleic genomes of I. trifida and sweetpotato, respectively. Functional gene annotation and RNA-Seq analysis revealed locations of starch, anthocyanin, and carotenoid pathway genes on the sweetpotato genome. This is the first report of chromosome-scale de novo assembly of the sweetpotato genome. The results are expected to contribute to genomic and genetic analyses of sweetpotato.

genomics↗

A bioactive phlebovirus-like envelope protein in a hookworm endogenous virus

Endogenous retroviruses (ERVs), accounting for 14% of our genome, serve as a genetic reservoir from which new genes can emerge. Nematode ERVs are particularly diverse and informative of retrovirus evolution. We identify Atlas virus - a novel, intact ERV in the human hookworm Ancylostoma ceylanicum with an envelope protein genetically related to GN-GC glycoproteins from phleboviruses. A cryo-EM structure of Atlas GC reveals a class II viral membrane fusion protein fold not previously seen in retroviruses. Atlas GC has the structural hallmarks of an active fusogen. Atlas GC trimers insert into membranes with endosomal lipid compositions and low pH. When expressed on the plasma membrane, Atlas GC has cell-cell fusion activity. Atlas virus is transcriptionally active at specific stages of hookworm development. The preserved activities and expression pattern of Atlas GC suggest it has acquired a cellular function. Our work reveals an unexpected degree of structural and genetic plasticity in retroviruses.

molecular biology↗