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Biology subjects

Sun, J.

Publications and source records attributed to Sun, J..

At least 91 records · Page 5Linked to original sources

Flexible Skull-Conformal Phased Array for Aberration-Corrected Transcranial Focused Ultrasound Therapy

Transcranial focused ultrasound (tFUS) is a promising non-invasive tool for precise deep-brain interventions, including neuromodulation, blood-brain barrier opening, and drug delivery. However, conventional rigid tFUS arrays suffer from poor skull conformity, compromising patient comfort and targeting precision, while skull-induced aberrations degrade focal accuracy and efficiency. To address these challenges, we present the first flexible, skull-conformal aberration-corrected phased array (F-SCAPA), a transformative solution integrating mechanical adaptability with advanced acoustic correction. The 0.5-MHz array--comprising 8x8 elements--features an optimized fabrication process that enhances material efficiency, ensures flexibility and stretchability, and maintains uniform electrical performance. Coupled with CT-based skull modeling and time-reversal aberration correction, F-SCAPA dynamically conforms to cranial anatomy while compensating for phase distortions. Transcranial validation in a human skull demonstrates precise focusing at 36 mm depth, achieving an axial full width at half maximum (FWHM) of 8.9 mm. This breakthrough overcomes existing limitations by combining mechanical adaptability with high-resolution transcranial focusing, establishing F-SCAPA as a robust, patient-compatible platform for next-generation non-invasive brain therapies.

bioengineering↗

Scalable integration and prediction of unpaired single-cell and spatial multi-omics via regularized disentanglement

Deciphering cellular states requires methods capable of integrating large-scale heterogeneous single-cell and spatial omics data. However, these data are typically unpaired due to destructive assays and further confounded by modality heterogeneity, technical noise, and immense scale. Here we present scMRDR, a scalable computational framework based on regularized disentangled representation learning for integrating fully unpaired single-cell and spatial multi-omics datasets. Built on a unified and structure-preserving architecture, scMRDR removes the need for pairing supervision while maintaining computational efficiency, enabling scaling to large datasets spanning multiple disparate omics modalities. Across diverse real-world benchmarks, scMRDR demonstrates strong performance in batch correction, modality alignment, and biological signal preservation. The framework further supports cross-modal translation across omics modalities and enables spatial coordinate imputation for non-spatial single-cell datasets using a reference atlas. The resulting spatial mapping allows spatially resolved analyses, including identification of spatially variable genes and characterization of epigenetic regulatory programs in their native tissue context. These capabilities position scMRDR as a scalable and versatile framework for large-scale multi-omics integration.

genomics↗

Single-cell disentangled representations for perturbation modeling and treatment effect estimation

Dissecting cell-state-specific changes in gene regulation induced by perturbations is crucial for understanding biological mechanisms. However, single-cell sequencing provides only unmatched snapshots of cells under different conditions. This destructive measurement process hinders the estimation of individualized treatment effects (ITEs), which are essential for pinpointing these heterogeneous mechanistic responses. We develop scDRP, a generative framework that leverages disentangled representation learning with asymptotic correctness guarantees to separate perturbation-induced and perturbation-invariant latent variables via a sparsity regularized {beta}-VAE. Assuming quantile-preserving effects of perturbations conditional on confounders, scDRP performs conditional optimal transport in the disentangled latent space to infer counterfactual states and estimate ITEs. Applied to simulated and real single-cell perturbation data, scDRP accurately estimates treatment effects and individual counterfactual responses, with subsequent biclustering analysis further elucidating cell-type-specific functional gene module dynamics. Specifically, it captures distinct cellular patterns under rhinovirus and cigarette-smoke extract exposures, reveals heterogeneous responses to interferon stimulation across diverse immune cell types, and identifies distinct functional module activation in chronic myeloid leukemia cells following CRISPR activation targeting different genes. scDRP also generalizes to unseen perturbation doses and combinations. Our framework provides a principled computational approach to extracting heterogeneous causal relationships from single-cell perturbation data, enabling a deeper understanding of cellular and molecular mechanisms.

genomics↗

Orchestrating Spatial Transcriptomics Analysis with Bioconductor

Spatial transcriptomics technologies provide spatially-resolved measurements of gene expression through assays that can either target selected genes or capture transcriptome-wide expression profiles. The complexity and variability of these technologies and their associated data necessitate multi-step workflows integrating diverse computational methods and software packages. We provide a freely accessible, open-source, continuously updated and tested online book containing reproducible code examples, datasets, and discussion about data analysis workflows for spatial omics data using Bioconductor in R, including interoperability with Python.

bioinformatics↗

Identification and Characterization of a Small Molecule Ligand for the Huntingtin-HAP40 Complex

Huntingtons disease (HD) is caused by a CAG repeat expansion mutation, giving rise to a polyglutamine expansion in the huntingtin (HTT). However, the explicit molecular functions of HTT and opportunities for direct pharmacological modulation remain incompletely understood. Here, we report the discovery of a small molecule ligand for the full-length HTT protein in complex with its partner, HAP40. Using affinity selection mass spectrometry (AS-MS), we identified a stereoselective binder, whose binding was characterized by surface plasmon resonance, hydrogen-deuterium exchange mass spectrometry, and cryo-electron microscopy at 2.3 [A] resolution. The ligand binds HTT-HAP40 in vitro with single-digit micromolar affinity and one-to-one stoichiometry at a druggable interface previously predicted computationally. In silico studies predicted and experimental analyses confirmed the (R)-enantiomer as the eutomer and initial structure activity relationship was established experimentally. This work details a structurally-validated chemical scaffold and highlights a ligandable pocket which could enable development of chemical probes for probing HTT biology, as well as therapeutics such as degraders and imaging agents for HD.

pharmacology and toxicology↗

Skull Bone Marrow Drainage and Its Associations with Inflammation, Sleep Quality, and Cognitive Performance

BackgroundRecent studies using human craniotomy samples and murine models have revealed channels that connect the inner skull cortex to the skull marrow cavities. While cerebrospinal fluid (CSF) tracer access to skull bone marrow has been described in CSF circulation disorders, evidence on regional patterns and clinical correlates in broader clinical cohorts is limited. MethodsThree-dimensional imaging was performed at baseline, 4.5, 15, and 39 hours post-gadolinium administration in 87 patients with neurological conditions. Signal changes in skull bone marrow near the superior sagittal sinus, lateral fissure, and cisterna magna were recorded. CSF drainage function was characterized as the percentage changes in the signal unit ratio within the skull bone marrow from baseline to time points post administration of gadolinium. ResultsThe tracer drained from CSF into the skull bone marrow, highlighting the drainage variations nearby different regions. Reduced drainage was associated with female sex, hypertension, diabetes, and elevated neutrophil levels (p < 0.05). Drainage near the superior sagittal sinus was inversely associated with sleep quality and positively associated with cognitive scores, and partially accounted for the association of sleep quality with cognitive function (indirect effect {Delta}{beta} = -0.092; bootstrap 95% CI -0.195 to -0.004; proportion mediated {approx} 38%). ConclusionThese results support the presence of skull bone marrow adjacent routes for CSF tracer movement and suggest that skull bone marrow tracer dynamics relate to systemic inflammation, sleep quality, and cognitive performance in this clinical cohort.

neuroscience↗

Generative Design of Cell Type-Specific RNA Splicing Elements for Programmable Gene Regulation

Programmable control of gene expression in specific cell types is essential for both basic discovery and therapeutic intervention, yet current strategies lack scalability across diverse cellular contexts. Here, we introduce SPICE (Splicing Proportions In Cell types), an integrated experimental and computational framework that harnesses alternative RNA splicing as a programmable modality for cell type-specific gene regulation. To power SPICE, we constructed a massively parallel reporter assay (MPRA) comprising 46,372 human-derived sequences and profiled exon skipping across 43 cell lines spanning 10 lineages, uncovering widespread cell type-specific exon skipping. Using this data, we trained deep learning models that both predict splicing in unseen contexts and generate synthetic sequences with programmed, cell type-specific splicing patterns. Leveraging these models, we further engineered sequences that selectively splice in cells harboring oncogenic splicing factor mutations, demonstrating translational potential. SPICE provides a generalizable strategy for dissecting splicing regulation and engineering alternative splicing as a gene expression regulatory layer for research and therapeutic applications. One Sentence SummaryWe introduce SPICE, an integrated framework that couples large-scale splicing assays with generative design to uncover regulatory principles and design programmable, cell-specific gene expression for research and therapeutic applications.

molecular biology↗

Two routes to land: Genomic underpinnings of parallel aerial egg deposition in aquatic Old-World Pila and New-World Pomacea (Ampullariidae)

The parallel evolution of aerial oviposition in Old-World Pila and New-World Pomacea apple snails--diverged since the Gondwanan breakup yet convergently transitioning from aquatic to terrestrial egg deposition--offers a powerful model for probing genomic adaptations underpinning key evolutionary innovations. We generated chromosomal-level genomes of Pila celebensis and Pila pesmei, revealing a genus-specific doubling in genome size driven by transposable element expansions. Parallel chromosomal rearrangements linked to environmental sensing, stress responses, and metabolism were identified in both lineages. Gene family analyses uncovered parallel expansions in cellulases, immune genes, and environmental sensors, alongside convergent positive selection in aquaporins critical for aerial osmoregulation. Strikingly, proteomics of egg perivitelline fluid (PVF) highlighted parallel adaptations in the PV1 protein family, where increased hydrophobicity enhances desiccation resistance in aerially deposited eggs. Phylogenetic and structural evidence traced PV1s likely origin to horizontal gene transfer (HGT) from a virus in the Ampullariidae ancestor, with subsequent duplications enabling lineage-specific aerial adaptations. Despite distinct genomic trajectories, Pila and Pomacea demonstrate that parallel molecular evolution and HGT-driven innovation facilitated their convergent transition to terrestrial reproduction, providing unprecedented insights into the genomic architecture of adaptive convergence.

evolutionary biology↗

Quantifying the impact of genetic mutations on enhancer dynamics

Transcriptional regulation is mediated by enhancers, yet how genetic perturbations alter enhancer activity and gene expression remains poorly understood. We developed UDI-UMI-STARR-seq, which integrates dual indexes and unique molecular identifiers, and combined it with RNA-seq to profile the effects of perturbations on enhancer activity and target gene expression. We applied this approach to a library of 253,632 fragments representing 46,142 cell type-specific candidate enhancers and assessed the impact of CRISPR/Cas9-mediated deletion of six transcription factors (or TFs; ATF2, CTCF, FOXA1, LEF1, TCF7L2, and SCRT1) with diverse regulatory roles. Across knockout lines, we identified responsive enhancers that were either repressed or induced, often through motifs such as the p53 family of TFs. Enhancer-gene mapping revealed TF-specific programs, including repression of Wnt/p53 targets with ATF2 or LEF1 loss, downregulation of the FIRRE locus with CTCF loss, and compensatory upregulation of RNA polymerase II regulators following FOXA1 depletion. A deep learning model trained on enhancer sequences recapitulated core principles of enhancer grammar, including cooperative motif syntax and the influence of flanking sequence context. Applying this framework to the neurodevelopmental disorder-associated 16p12.1 deletion identified responsive enhancers linked to genes involved in axon guidance, synaptic plasticity, and translational control, providing a scalable readout of enhancer dynamics generalizable to genetic mutations.

genomics↗

Distinct 5' and 3' Coverage Biases Shape Transcriptome Interpretation in Nanopore Direct RNA versus PCR-cDNA Sequencing

Long-read RNA sequencing enables isoform-resolved transcriptomics, but library preparation introduces systematic biases that shape biological interpretation. We benchmarked Oxford Nanopores two protocols--PCR-cDNA and direct RNA--using SKMM2 myeloma cells stimulated with interleukin-6 (IL-6) and ERCC synthetic spike-ins. Direct RNA produced longer, higher-quality reads and more high-confidence isoforms, but showed pronounced 5' coverage loss. PCR-cDNA yielded shorter fragments with 3' underrepresentation, detecting more low-abundance transcripts at reduced confidence. Protocol-specific biases had major consequences: differential expression analysis revealed limited overlap in IL-6-responsive genes, and pathway enrichment was broader in direct RNA. At the isoform level, differential transcript usage was almost entirely protocol-specific, with case studies (e.g. RPL22L1, GRB2, RNF220) illustrating concordance and divergence. ERCC controls confirmed these biases as technical rather than biological. Together, our results show that while both methods provide accurate gene-level quantification, transcript-level conclusions depend critically on protocol choice, highlighting the need for careful selection in long-read transcriptomics.

cell biology↗

tRNA Modification Landscapes in Streptococci: Shared Losses and Clade-Specific Adaptations

tRNA modifications are central to bacterial translational control. Here, we integrated genetics, mass spectrometry, epitranscriptomics, and comparative genomics to map the tRNA modification genes of the Gram-positive pathogens Streptococcus mutans and Streptococcus pneumoniae. Both species show a marked loss of modifications dependent on Fe-S enzymes, consistent with a broader trend of Fe-S enzyme reduction in Streptococcus central metabolism. In addition, the D, m1A, m7G, t6A, and i6A modifications were mapped in S. pneumoniae tRNAs, and we confirmed that a unique DusB1 enzyme is responsible for the insertion of all the detectable D modifications. We uncovered differences in queuosine (Q) metabolism: while S. mutans synthesizes Q de novo, S. pneumoniae instead salvages preQ and accumulates the epoxy-Q precursor, a strategy shared with multiple other Streptococci as revealed by analysis of Q pathways in 1,599 sequenced streptococcal genomes. Comparative essentiality profiling of modification genes revealed notable differences, including the essentiality of the NLJ-threonylcarbamoyladenosine (tLJA) synthesis enzyme TsaE in S. pneumoniae but not in S. mutans, which was confirmed by genetic studies. We found that suppressor mutations in asnS encoding asparaginyl-tRNA synthetase (AsnRS) restored viability to {Delta}tsaE mutants, albeit with reduced growth. Our finding highlights the functional importance of modifications in the recognition of tRNAs by aminoacyl-tRNA synthetases.

microbiology↗

PymolFold: A PyMOL Plugin for API-driven Structure Prediction and Quality Assessment

Deep learning has transformed protein structure prediction, yet many experimental scientists face barriers in accessing state-of-the-art (SOTA) models due to technical complexity and hardware requirements. To address this, we present PymolFold, an open-source PyMOL plugin that seamlessly integrates cutting edge API-based protein structure predictors such as ESM-3 and Boltz2 into the molecular visualization environment. PymolFold supports both graphical and command-line interfaces for flexible usage and incorporates PXMeter, an open-source Python package for quantitative evaluation of protein structure predictions against reference data. Together, these features establish a unified "predict-visualize-analyze" workflow, lowering technical entry barriers and broadening access to advanced structural modeling. PymolFold is freely available at https://github.com/jinyuansun/PymolFold.

bioinformatics↗

Targeting a macrophage stemness factor to mitigate diseases post respiratory viral infection

Tissue-resident alveolar macrophages (AMs) rely on intrinsic stem-like programs for self-renewal and maintenance, yet the transcriptional networks that support these functions and their relevance to post-viral lung disease remain largely unknown. Here, we identify TCF4 (Tcf7l2) as a critical transcription factor that governs AM maturation and stemness. Loss of TCF4 impaired AM proliferation, shifted their identity toward a pro-inflammatory phenotype, and exacerbated host morbidity following influenza or SARS-CoV-2 infection. Conversely, enforced TCF4 expression promoted the expansion of mature AMs, and supported lung recovery, thereby protecting against severe acute viral disease. Mechanistically, TCF4 antagonized {beta}-catenin-driven inflammatory transcription while preserving oxidative phosphorylation, defining a reciprocal regulatory axis essential for AM function. Notably, respiratory viral infections and exuberant interferon signaling suppressed TCF4 expression, which remains chronically reduced in murine and human lungs with post-COVID fibrosis. This downregulation is associated with persistent KRT8hi dysplastic epithelium and collagen deposition. Moreover, aging diminished TCF4 levels and enforced TCF4 expression dampened age-associated decline of AM self-renewal. Furthermore, in vivo TCF4 overexpression after viral clearance enhanced mature AM accumulation, promoted lung epithelium regeneration, attenuated chronic tissue fibrosis and restored pulmonary physiologial function in aged lungs in a model of persistent pulmonary fibrosis post-acute viral infection. These findings have established TCF4 as a key regulator of AM stemness and identified a promising therapeutic target for long COVID and related chronic lung diseases through the modulation of embryonic-derived macrophage regenerative capacity by targeting TCF4.

immunology↗

A load-bearing function for the cytoplasmic membrane of Escherichia coli

The structural integrity of bacterial cells is traditionally attributed to the peptidoglycan cell wall, and more recently to the outer membrane, with the cytoplasmic membrane assumed to be mechanically passive. Cells lacking filaments of the actin homolog MreB are more bendable, suggesting a role for the cytoskeleton in cell stiffness. Here, we show that MreB does not stiffen the envelope directly, but instead mechanically couples the cell wall to the cytoplasmic membrane through its role in peptidoglycan synthesis, increasing resistance to bending. Under hyperosmotic stress, MreB relocalized to the poles, forming linkages that prevent membrane detachment from the cell wall and attenuate cytoplasmic contraction. Disruption of MreB filament formation, nutrient starvation, or inactivation of glycan elongation factors abolished or reduced this coupling, revealing that peptidoglycan biosynthesis actively mediates stress distribution across surface layers. Our findings redefine the bacterial envelope as a mechanically integrated composite, with the cytoplasmic membrane having substantial load-bearing capacity.

microbiology↗

Compositional and Functional Profiling of the Gut Microbiome in Sarcoidosis

BackgroundSarcoidosis is a chronic inflammatory disease characterized by systematic granuloma formation, predominantly in the lungs. One leading hypothesis posits that prolonged exposure to microbial antigens may trigger chronic and dysregulated inflammation. Prior studies have examined the lung microbiota of sarcoidosis patients, but the role of the gut microbiota along the gut-immune axis remains largely unexplored. We elucidate the community composition and function of the gut microbiome in sarcoidosis. MethodsSubjects diagnosed with sarcoidosis (n=37) were recruited and matched with healthy control subjects (n=37). Stool samples were collected from sarcoidosis patients for metagenomic sequencing, followed by taxonomic classification and functional annotation as KEGG Orthology (KO) pathways. Differential analysis between sarcoidosis and control cohorts was performed using both standard and compositional approaches. ResultsSarcoidosis microbiomes exhibited similar alpha diversity but significantly different beta diversity from control microbiomes (p<0.05). At the phylum level, the proportion of Actinobacteria and Firmicutes expanded whereas Bacteroides and Verrucomicrobia proportionally shrunk in sarcoidosis gut microbiomes compared to healthy control ones. At the species level, 1,495 species were significantly more abundant and 279 less abundant in sarcoidosis compared to controls (FDR<0.05). Of these, 13 species demonstrated greater intergroup than intragroup variation (effect size>1), including microbes previously detected in the lungs and granulomas of sarcoidosis. Functional profiling revealed 409 KO pathways that were significantly underrepresented in sarcoidosis compared to control (FDR<0.05), of which 79 met an effect size > 1. These include pathways in amino acid and energy metabolism as well as HIF-1 signaling. ConclusionsOur findings highlight the potential role of gut microbiome composition and function in inflammatory processes that are associated with granuloma formation in sarcoidosis and warrant further investigation into gut hyperoxia-driven dysbiosis.

microbiology↗

Mechanisms of superior respiratory IgA responses against SARS-CoV-2 after mucosal vaccination

Mucosal immunization and respiratory IgA offer significant promise in protecting against airborne pathogens, including SARS-CoV-2. However, the conditions and mechanisms that lead to the robust induction of respiratory IgA responses following mucosal vaccination remain poorly understood. It is also currently debatable whether mucosal vaccination is still warranted given that most individuals in developed countries have established a hybrid immunity from vaccination and infection. Here we characterized respiratory mucosal immune responses after SARS-CoV-2 infection, vaccination or both in humans. We found that hybrid immunity resulted in moderately increased respiratory IgA and neutralizing antibody responses compared to infection or vaccination alone. However, a direct comparison of hybrid immunity and a mucosal adenovirus-based booster vaccination in animal models revealed that respiratory booster immunization elicited markedly stronger and more durable respiratory IgA, T cell response, and protective immunity against SARS-CoV-2, supporting the promise of respiratory mucosal vaccination. Mechanistically, we found that mucosal booster immunization induced local IgA- secreting cells in the respiratory mucosa, aided by pulmonary CD4+ T cells in situ. Strikingly, local IL-21-producing Blimp-1+ Th1 effector cells were critical in mediating the CD4+ T cell help for respiratory IgA production. Furthermore, lung macrophages were important for this respiratory IgA response via the production of TGF-{beta}. Consequently, we demonstrated delivery of adenoviral booster to the lower airway was necessary to generate robust upper and lower airway IgA responses. Collectively, our results uncover a local cellular network supporting enhanced respiratory IgA responses, with implications for the development of optimal mucosal immunization strategies against SARS-CoV-2 and other respiratory pathogens.

immunology↗

Integrative Systems Biology Identifies the AHR Signaling Axis as a Mechanistic Basis for Xiaobi Plaster in Lumbar Disc Degeneration

BackgroundLumbar disc degeneration (LDD) is characterized by chronic inflammation, oxidative stress, and extracellular matrix (ECM) breakdown, yet current therapies provide only symptomatic relief. Xiaobi Plaster (XBG), a traditional Chinese transdermal herbal preparation, has shown clinical benefit, but its molecular mechanisms remain unclear. MethodsWe applied an integrative systems biology framework combining network pharmacology, machine learning, and transcriptomic validation to identify candidate targets of Xiaobi Plaster in LDD. Molecular docking, dynamics simulations, and immune infiltration analysis further elucidated the underlying mechanisms, which were experimentally validated in a rat puncture-induced degeneration model. ResultsThree key targets--AHR, PTPN2, and SOAT1--were identified, with AHR emerging as the central regulator. Differential expression and enrichment analyses highlighted inflammatory and ECM-remodeling pathways, which overlapped with AHR-specific GSEA, underscoring its hub role in integrating immune and redox signaling with matrix turnover. Molecular docking and 100-ns molecular dynamics confirmed rutaecarpine (MOL002662) as the most stable AHR ligand. Transcriptomic data further showed AHR expression correlates with degeneration severity and mast cell infiltration. In vivo qPCR and Western blotting validated upregulation of AHR and supporting roles of PTPN2 and SOAT1 in degenerative discs. ConclusionThis study elucidates the multi-target and multi-pathway mechanisms of XBG in LDD, highlighting AHR as a pivotal therapeutic target modulated by rutaecarpine, with PTPN2 and SOAT1 serving as auxiliary regulators. These findings provide mechanistic insights into the transdermal application of XBG and support the therapeutic relevance of targeting the AHR signaling axis in LDD.

bioinformatics↗

N6-Methyladenine DNA modification regulates pathogen virulence in nematodes

Understanding the global regulatory mechanisms that control pathogen virulence gene expression is essential for elucidating the molecular basis of pathogenicity. N6-methyladenine (6mA) plays a crucial role in regulating gene expression in response to various environmental stresses; however, its role in pathogen virulence remains largely unexplored. Here, we report the widespread occurrence of 6mA across 17 nematode isolates and map its genomic landscape in six notorious agriculturally important pathogen root-knot nematodes (RKNs). We demonstrated that 6mA is characterized by a conserved GAG motif across nematodes, but exhibits species-specific distribution patterns and distinct effects on gene expression. In particular, its enrichment in transposable elements differs between polyploid and diploid nematodes, suggesting lineage-specific epigenetic regulation potentially associated with polyploidy. We further identified two functional 6mA demethylases, MiNMAD-1 and MiNMAD-2, and confirmed their catalytic activity and active sites. Host-induced gene silencing of minmad-1 significantly increased plant resistance to three polyploid RKN species. A detailed functional analysis revealed that minmad-1 knockdown disrupted virulence gene expression during the parasitic stage, thereby reducing nematode infectivity. Together, our findings suggest 6mA demethylase as a key epigenetic regulator of RKNs virulence, providing new insights into nematode biology and offering promising targets for the development of sustainable control strategies. Significance Statement6mA methyltransferase regulates the expression of virulence genes in certain pathogenic bacteria and plays a critical role in their infectivity. However, the regulation of virulence gene expression in eukaryotic pathogens, particularly plant pathogens, remains poorly understood. Most studies on pathogen virulence have focused on individual effectors, with little insight into global regulatory mechanisms. Here, we demonstrate that 6mA broadly shapes virulence gene expression patterns in polyploid RKNs. Moreover, transgenic tobacco, tomato, and rice plants expressing dsRNA against nematode demethylases showed significantly enhanced resistance to RKNs. These findings establish 6mA demethylase as a promising epigenetic target for controlling plant-parasitic nematodes.

molecular biology↗