Biology subjects

Kim, J.

Publications and source records attributed to Kim, J..

At least 73 records · Page 4Linked to original sources

bioRxiv2026

The basal cell state maintains pancreatic cancers by controlling an immunosuppressive circuit

Intra-tumoral heterogeneity is a cardinal feature of solid tumors, yet how distinct cancer cell states functionally contribute to malignant and stromal diversity in situ remains poorly understood. Using mouse models to lineage-trace or genetically ablate the two predominant cancer cell states in autochthonous pancreatic ductal adenocarcinoma (PDAC), we discover that basal cancer cells are highly plastic, whereas classical cancer cells exhibit limited plasticity. Strikingly, ablation of the basal, but not the classical, state induced rapid and durable tumor collapse, driven by loss of immunosuppressive cancer-associated fibroblasts, macrophage repolarization, and reprogramming of the tumor cytokine milieu, culminating in tumor destruction by cytotoxic lymphocytes. Knockout of a single cytokine, GM-CSF, specifically in basal cells recapitulated macrophage repolarization and lymphocyte recruitment observed upon basal state ablation and shrank tumors. These results reveal the basal cell state controls an immunosuppressive cell circuit critical for PDAC maintenance, motivating therapeutic targeting of the basal cells.

cancer biology↗

bioRxiv2026

Confined T cell migration controls programmed cell death 1 expression

T cell immune checkpoint expression and dysfunction are attributed solely to molecular cues. We discover using microphysiological systems and in vivo models that transmigration through confined pores induces acute loss of programmed cell death 1 within minutes of surface immune checkpoint markers on CD8+ T cells through ubiquitin-mediated proteasomal degradation, corresponding with enhanced fitness and function. Such imprints and its underlying mechanism of programmed cell death 1 loss are conserved across species and applicable to human TIL and CAR T cells, and are correlative with disease outcomes in human melanoma. Our findings establish the diverse tissues landscapes that T cells traverse during immunosurveillance, and specifically transmigration, as a form of mechanical immune regulation, and reveal a mechano-modulatory strategy to improve the quality and persistence of engineered or patient-derived T cells for adoptive immunotherapy.

immunology↗

bioRxiv2026

First community challenge for automated virus taxonomy

The rapid rate of virus discovery renders manual curation by taxonomy experts increasingly impractical, creating a need for reliable software that can reproducibly assign viral contigs to taxa at all fifteen ranks of the virus taxonomy. We led an open community challenge for the computational taxonomic classification of viruses and assembled a dataset of virus sequences combining expert-curated and metagenomic sequences. Seventeen teams contributed a total of thirty-four automated, fully reproducible classification pipelines. Most tools correctly assigned viruses belonging to established species, genera, or families, but viruses that are unclassified at those lower ranks remain challenging. This study provides datasets, open-source software, novel approaches, and recommendations to benchmark computational taxonomic classification of viruses, and support organizing the many viruses discovered in big omics data.

microbiology↗

bioRxiv2026

Spatial Metabolomics by Desthiobiotin Ligase (DESTNI) in Live Cells

Proximity labeling has transformed spatial proteomics by enabling compartment-resolved mapping of protein environments in living cells, yet its extension to small-molecule metabolites has not been demonstrated, probably due to limitations in labeling chemistry and labeled metabolites identification. Here, we introduce DESTNI, an engineered desthiobiotin (DTB) ligase derived from TurboID through directed evolution, and establish a platform for spatially resolved profiling of amine-containing metabolites. A directed evolution strategy based on a yeast display system yielded DESTNI with efficient DTB-dependent reactivity, enabling robust and compartment-specific proximity labeling across diverse subcellular environments. To identify the DTB-modified amino metabolome, we developed an integrated analytical framework combining DTB-modified amino metabolite standards, in vitro DESTNI profiling, and in silico MS/MS prediction, enabling systematic annotation of DTB-modified amino metabolites. To extend this chemistry to metabolites, we combined synthetic DTB-conjugated metabolite reference standards, in vitro DESTNI-reactive metabolite discovery, and machine-learning prediction of DTB-derivatized metabolites and oligopeptides. Organelle-targeted DESTNI recovered reproducible compartment-enriched amino metabolite signatures, including mitochondrial matrix-enriched glycine, 5-aminolevulinic acid, ornithine and spermidine adducts, as well as nuclear-enriched {gamma}-aminobutyric acid and 5-aminovaleric acid adducts. Together, this work establishes DESTNI as a proximity labeling platform that bridges spatial proteomics and metabolomics and provides a general strategy for mapping subcellular biochemical environments in living cells.

biochemistry↗

bioRxiv2026

P-DOpE probes reveal local amplification of phasic noradrenergic release in the hippocampus

Fiber photometry (FP) has become a tool of choice for in vivo monitoring of genetically encoded biosensors. The ability to record and optogenetically manipulate circuits through the same fiber stub is powerful, but limited, as biosensors typically do not sample membrane voltage, leaving the experimenter blind to the direct effects of opsin photoactivation. Here we developed the Photometry Device with Optogenetics and Electrophysiology (P-DOpE) probe, fabricated via a new convergence taper-break (CTB) method that integrates industry-standard silica optical waveguides with low-impedance metal electrodes that can be arranged in experimenter-defined configurations. We demonstrate that chronically implanted P-DOpE probes provide months-long recordings of local field potential, single unit recording, and fiber photometry, with parallel optogenetic circuit perturbation. Conducting fiber photometry with same-site optogenetic stimulation, we identified a robust fluorescence signal that scaled with network activity and survived biosensor antagonism. As this confound could not be eliminated with standard isosbestic controls, we propose a simple correction strategy. As a first application, we used the probe to test a proposed mechanism for focal modulation of noradrenergic signaling in and by cortical circuits receiving afferents from the locus coeruleus. We found that increasing spiking activity in CA1 amplifies noradrenergic signaling evoked by contextual arousal by [~]50%, but does not induce norepinephrine release in the absence of a phasic trigger - thus supporting the central prediction of the glutamate amplifies noradrenergic effects (GANE) hypothesis. The P-DOpE probe thus enables optogenetic manipulation and multimodal readout in a configurable low-cost, scalable, and robust format.

neuroscience↗

bioRxiv2026

DNA methylation maintenance by DNMT1 is essential for human trophoblast stem cell homeostasis and differentiation

Proliferation of cytotrophoblasts (CTBs) and their differentiation into invasive extravillous trophoblasts (EVTs) are critical processes in early placental development. Defects in these processes are associated with adverse pregnancy outcomes, including recurrent pregnancy loss (RPL). There is evidence that reduced expression of the maintenance DNA methyltransferase DNMT1 in the placenta occurs in pregnancy loss and that RPL is associated with aberrant DNA methylation patterns. Therefore, we investigated the role of DNMT1 in human trophoblast growth and differentiation. Using human trophoblast stem cells (hTSCs), an in vitro analog to CTBs, we found that shRNA-mediated knockdown of DNMT1 led to decreased hTSC proliferation, genome-wide reductions in methylation, broad changes in gene expression, and impaired EVT differentiation. Transcriptome profiling of DNMT1-deficient hTSCs and hTSC-derived EVTs highlighted aberrant cytokine expression, drawing a connection to prior reports of immunological dysfunction in RPL. Finally, using a catalytic DNMT1 chemical inhibitor, we demonstrate the canonical methyltransferase activity of DNMT1 is essential for EVT differentiation and invasion. This study identifies new roles for DNMT1 in trophoblasts and addresses the molecular basis of the associations between DNMT1 expression, altered DNA methylation profiles, and RPL.

developmental biology↗

bioRxiv2026

The AadR-FixK hierarchy coordinates iron-responsive metabolism via Fur-family regulators in Rhodopseudomonas palustris TIE-1

Rhodopseudomonas palustris (Rp.) is a metabolically versatile environmental bacterium that flourishes across gradients of iron, oxygen, and light. The varying metabolic landscapes Rp. exploits have pressured it to evolve hierarchical regulatory networks, enabling tuneable expression in response to multiple input signals. However, many studies of regulation in this organism have used standard laboratory conditions: incandescent illumination and single-substrate growth, which do not fully engage the complexity of its regulatory networks and lack relevance to natural environments. Rp. can generate energy through light-powered iron oxidation via the PioABC system, and swathes of its anaerobic metabolism employ proteins using ferrous cofactors produced from bioavailable Fe(II). Rp. lacks the Fe(II)-sensing regulators found in related lineages, leaving it unclear how it balances expression of anaerobic metabolic pathways with sensed iron levels. Using what we term naturomimetic conditions, including growth with simultaneous provision of an organic carbon source and Fe(II), we uncovered a surprising link between oxygen-responsive and iron-responsive regulatory networks in Rp. FixK and AadR mediate the regulatory shift from aerobic to anaerobic metabolism, but, as we demonstrate here, they also orchestrate the response to Fe(II) by modulating a secondary network of Fur-family regulators. {Delta}aadR and {Delta}fixK strains were both defective in iron metabolism, and {Delta}aadR showed perturbed expression of all four Fur-family regulators, sometimes in entirely opposite directions. Our findings establish that iron regulation in Rp. occurs via a regulatory network integrating multiple environmental signals. Phylogenetic analyses suggest conservation of network components across several related evolutionary lineages, including Bradyrhizobium.

microbiology↗

bioRxiv2026

Cryo-EM structures of Arabidopsis PRC2 histone methyltransferase isoforms reveal a differential regulatory mechanism

Polycomb Repressive Complex 2 (PRC2) is a histone H3K27 methyltransferase that represses gene expression. Arabidopsis thaliana (A. thaliana) has several different PRC2 isoforms that are functionally distinct during the life cycle of the plants. However, their biochemical and structural characteristics have not been investigated. Here, we biochemically characterized PRC2 isoforms having different catalytic subunits: SWNINGER (SWN; PRC2SWN) and CURLY LEAF (CLF; PRC2CLF). Interestingly, PRC2SWN showed much lower activity than PRC2CLF. In addition, PRC2SWN methylates histone H3K27 in mono and di-methylation, while PRC2CLF shows robust tri-methylase activity. We also determined the cryo-electron microscopy (cryo-EM) structures of PRC2SWN and PRC2CLF, revealing that the substrate binding pocket of the SWN SET domain is blocked by a loop in the pre-SET domain, functioning as an auto-inhibitory loop, while that of the CLF SET domain is freely accessible. Introduction of CLF-like mutations in the auto-inhibitory loop in SWN enhances PRC2SWN activity. Furthermore, structure-guided in planta analysis shows that a CLF-mimetic SWN mutant rescues the CLF knockout phenotype. Our work provides structural and molecular insights into the isoform-specific regulatory mechanism of plant PRC2.

Plant Biology↗

bioRxiv2026

A Snakemake-based bacterial whole genome comparison pipeline for multi-group clinical isolates

Organisms have continuously evolved in response to environmental conditions. Pathogenic bacteria evolve under host and environmental pressures, reshaping their genomes through insertions, inversions, deletions, and duplications during infection. In clinical settings, phenotypic traits of pathogenic bacteria such as virulence or antimicrobial resistance directly affect disease severity, transmission, and treatment. Conventional genotyping provides insights into genomic relatedness but does not always align with these clinically relevant traits, limiting its utility for phenotype-driven interventions. Here, we develop ABComp (Assembly polishing and Bacterial whole-genome Comparison for multi-group clinical isolates), a modular and Snakemake-based workflow for phenotype-driven comparative genomics. ABComp automates assembly polishing, group-wise pangenome analysis, and enables flexible pathogenic marker discovery through user-defined comparisons. We validated ABComp using a Klebsiella pneumoniae ground truth dataset stratified by yersiniabactin presence and successfully recovered the entire locus as a group-specific core marker. By applying ABComp to another dataset of clinical isolates with experimentally measured virulence, we discovered the ferric citrate (Fec) uptake system as a potential marker specific to a hypervirulent group. These results demonstrate ABComps utility in uncovering phenotype-linked genomic markers with clinical significance, supporting targeted treatments and rapid diagnosis.

bioinformatics↗

bioRxiv2026

Bispecific Antibody Architecture and TNFRSF Target Selection Determine CD8+ T Cell Differentiation and Anti-tumour Immunity

Tumour necrosis factor receptor superfamily (TNFRSF)-targeting bispecific antibodies (bsAb) enable tumour-localised T cell co-stimulation, yet how antibody architecture and receptor choice govern activity remains unclear. Here we define how bsAb format and TNFRSF target selection shape CD8+ T cell responses and anti-tumour immunity. Using B7-H3 as a tumour-associated antigen, we show that dual-bivalent 2x2 bsAb elicit maximal agonistic activity, whereas the corresponding monovalent 1x1 format is least active. A 2x1 format retaining TNFRSF bivalency but monovalent B7-H3 binding preserves substantial activity, identifying co-stimulatory receptor bivalency as a key determinant of efficacy. Across TNFRSF targets, 4-1BB drives the strongest cytotoxic CD8+ T cell differentiation and anti-tumour response. This superiority is conserved in human T cells and reproduced by cognate ligands, indicating that the observed functional hierarchy reflects receptor-intrinsic biology. Mechanistically, efficacy requires tumour-associated B7-H3 and T cell-dependent 4-1BB signalling. Together, these findings establish general principles linking antibody architecture and receptor biology to co-stimulatory bsAb efficacy and provide a framework for rational design leading to optimal therapeutics.

immunology↗

bioRxiv2026

Representational similarity analysis of EEG reveals multiple spatiotemporal dynamics of selective attention

Selective attention allows listeners to follow a target speaker in complex scenes, but less is known about the neural mechanisms that control this capacity. We collected electroencephalography (EEG) during an auditory attention task encompassing spatial attention, talker-based attention, and passive listening. Time-resolved representational similarity analysis (RSA) of broadband scalp voltage and alpha-band oscillations revealed distinct representational trajectories in the two measurements: scalp voltage produced brief peaks in task discriminability shortly after the target cue and around 300 ms after target onset, whereas alpha-band power emerged more slowly and remained elevated throughout the trial. These patterns distinguish attentive from passive conditions and spatial from talker attention. Furthermore, broadband activity and alpha power encode complementary information, while other frequency bands contribute little independent explanatory power. These results demonstrate that RSA allows a unified interpretation of evoked and induced EEG measures, revealing how distinct neural computations jointly encode the spatiotemporal dynamics of selective attention.

neuroscience↗

bioRxiv2026

Tumor-Derived SPP1 Drives Immunosuppressive Macrophage Reprogramming in Gastric Peritoneal Carcinomatosis

Peritoneal carcinomatosis is a major cause of death in gastric cancer, yet effective therapies remain limited. Tumor-derived soluble factors are increasingly recognized as key regulators of the peritumoral microenvironment. Here, we nominate osteopontin (SPP1) as a tumor-derived mediator that orchestrates macrophage-driven immunoregulation in gastric peritoneal carcinomatosis. Using integrated analyses of human clinical datasets and murine models, we demonstrate that tumor-secreted SPP1 promotes macrophage recruitment and induces tolerogenic IL-10 production. Clinically, SPP1 correlated with inferior overall survival and progression-free survival in gastric cancer. In syngeneic murine models of gastric peritoneal carcinomatosis, intracavitary pharmacologic inhibition of SPP1 restricted peritoneal dissemination, impaired macrophage infiltration and suppressed IL-10 production. Consistent with these findings, macrophage depletion phenocopied antitumor effects of SPP1 inhibition, resulting in decreased metastatic burden. Collectively, these findings define a mechanism of tumor-macrophage crosstalk that promotes peritoneal dissemination and provide a rationale for therapeutic targeting of SPP1 in gastric peritoneal carcinomatosis.

Cancer Biology↗

bioRxiv2026

MOTS-c Coordinates Inter-Organellar Proteostasis for Adaptation to Chronic Metabolic Stress

Mitochondrial communication coordinates adaptive responses across organelles to sustain cellular homeostasis, a network that declines with age and contributes to loss of proteostasis. Here, we identify MOTS-c, an exercise-induced mitochondrial-derived peptide (MDP) encoded within the 12S rRNA locus, as an inter-organellar arm of the mitochondrial stress response (MSR) that links mitochondrial signaling to endoplasmic reticulum (ER) proteostasis and enables adaptation to chronic stress. Using progressive stress media (PSM), a model of gradual and multifactorial metabolic stress, we show that MOTS-c enables adaptation through a biphasic program: acutely, a reversible, ATF4-independent suppression of protein synthesis; and chronically, an ATF6-biased ER unfolded protein response (UPRER) with tempered ATF4 engagement and coordinated metabolic remodeling. Whereas mitochondrial unfolded protein response (UPRmt) pathways have been extensively characterized in acute, genetic, and sustained models of mitochondrial perturbation, this work reveals how mitochondrial communication actively engages ER proteostasis during progressive and persistent metabolic stress. By expanding proteostatic capacity while tempering terminal stress signaling, MOTS-c enables cells to withstand chronic stress. Together, these findings define a MOTS-c-dependent arm of the MSR that integrates mitochondrial communication with ER proteostasis to promote chronic metabolic stress adaptation.

Cell Biology↗

bioRxiv2026

Multiomic profiling of LKB1 loss of expression in breast cancer

The tumour suppressor LKB1 (STK11) is implicated in diverse cancers, yet its transcriptomic role in breast cancer remains poorly defined. Here, we integrate bulk-tumour genomic analysis of the METABRIC cohort, CRISPR-Cas9-mediated STK11 knockout in human breast cancer cell lines, single-cell RNA sequencing of patient tumours, and a novel Lkb1 murine model to characterise LKB1-dependent transcriptomic programmes across breast cancer subtypes. We discovered that the loss of STK11 induced divergent, subtype-specific gene expression changes, suppressing estrogen, progesterone and androgen signalling pathways. In patient tumours, transcriptomic intratumour heterogeneity was highest in epithelial cells, where STK11 co-expression genes showed cell-type-selective patterns that was most striking in triple-negative breast cancer (TNBC), where STK11 was paradoxically upregulated in myoepithelial cells. While in a novel murine model, mammary-specific Lkb1 deletion drove tumourigenesis with long latency, confirming LKB1 loss as sufficient for malignant transformation with an underlying TNBC phenotype. STK11 mutations in METABRIC samples disproportionately affected the catalytic domain in TNBC tumours and were associated with immune evasion. Together these findings highlight that loss of Lkb1 is sufficient to drive breast tumourigenesis and uncover a new role for LKB1 in TNBC.

Cancer Biology↗

bioRxiv2026

Holotomography reveals biophysical remodeling of mouse oocytes during post-ovulatory aging

Routine assessment of oocyte state in reproductive biology and clinical embryology still relies largely on two-dimensional transmitted-light morphology, leaving the underlying three-dimensional intracellular organization largely unmeasured. Here, we use holotomography to reconstruct volumetric refractive index (RI) distributions in unlabeled live mouse oocytes and combine this imaging with sparse-annotation, AI-assisted compartment segmentation and multidimensional feature extraction across geometry, RI statistics, dry-mass density, and intracellular texture. Applied to an in vitro model of post-ovulatory aging, holotomography-derived biophysical profiles separated fresh and aged oocytes more strongly than two-dimensional brightfield-derived features, and feature-family ablation indicated that non-morphological descriptors contributed substantially to this separation. At the population level, aged oocytes showed coordinated ooplasmic remodeling, including reduced volume, increased RI heterogeneity, and increased dry-mass density while total dry mass was broadly conserved. These findings demonstrate a label-free quantitative framework for detecting post-ovulatory aging-associated biophysical remodeling in intact mammalian oocytes. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=167 SRC="FIGDIR/small/733271v1_ufig1.gif" ALT="Figure 1"> View larger version (89K): org.highwire.dtl.DTLVardef@c7257aorg.highwire.dtl.DTLVardef@6d92f0org.highwire.dtl.DTLVardef@1c9f7eborg.highwire.dtl.DTLVardef@b36637_HPS_FORMAT_FIGEXP M_FIG C_FIG

Developmental Biology↗

bioRxiv2026

Label-Free All-Electrical Tracking of Individual and Collective Cell Migration on a Megapixel CMOS Capacitance Sensor

Label-free tracking of adherent cell migration could enable important insights into biological processes such as tissue repair, inflammatory response, or cancer progression. Nevertheless, visualizing unlabeled animal cells using optical microscopy remains challenging due to low contrast as well as frequent changes in cell shape and number. A promising alternative uses electrical capacitance measurements, which are sensitive to cell adhesion to electrode surfaces. However, prior examples often utilized electrodes with areas larger than single cells, resulting in averaged readouts over multiple cells. Here, we demonstrate label-free, live-cell tracking using a capacitance sensor array with more than 1 million pixels on a 10 micron pitch across an area larger than 1 square centimeter. We show that single cell morphology can be clearly segmented, and then used to reconstruct migration and proliferation dynamics using optical flow. We further track the spreading of multicellular spheroids, revealing fast-moving peripheral regions led by a collective leader cell "front." Finally, we demonstrate label-free imaging of millimeter-scale honeycomb-shaped tissues without the multi-image stitching often required for conventional microscopy. We utilize mutual capacitance measurements with electrically-programmable electrode spacing to reconstruct topographical features of these engineered tissues. Overall, CMOS capacitance imaging arrays enables label-free imaging spanning from single cells to large tissues, in a portable and scalable format for settings where optical microscopy may be difficult to access.

bioengineering↗

bioRxiv2026

Generalisable tissue-wide molecular reconstruction from histology

Spatial transcriptomics technologies measure gene expression within intact tissues but remain difficult to scale across large tissue sections and patient cohorts. Consequently, many studies rely on tissue microarrays (TMAs) or sparse spatial profiling designs, where molecular measurements are available for only limited tissue regions and are often generated using heterogeneous gene panels. Existing H&E to spatial gene expression prediction methods remain challenged by sparse molecular measurements, partially overlapping gene panels and tissue-wide reconstruction across heterogeneous spatial datasets. Here, we present GHIST+, a framework for tissue-wide reconstruction of single-cell molecular states from H&E histology. GHIST+ integrates cellular morphology, local tissue context and shared tissue representations to extend sparse molecular measurements into tissue-wide molecular maps across heterogeneous spatial datasets. Across multiple cancer types and GTEx breast tissues, GHIST+ reconstructs biologically meaningful tissue-wide molecular organisation from sparse TMA-derived measurements while preserving spatial tissue structure, cell-type organisation and age-associated tissue states across cancer and non-cancer settings. GHIST+ establishes a scalable framework for transforming sparse spatial profiling experiments into tissue-wide molecular maps, enabling cohort-scale molecular reconstruction from routine histology under heterogeneous spatial transcriptomic settings.

bioinformatics↗

bioRxiv2026

Deconstructing a behavioral state: parallel neural integrators control distinct features of an aversive behavioral state in C. elegans

Transient sensory stimuli can trigger long-lasting changes in behavior and cognition. For example, repeated aversive experiences can lead to persistent changes in arousal and mood. Specialized integrator circuits can store information about recent experiences, but how they are embedded within the architecture of the brain to control internal brain states remains poorly understood. We find that C. elegans accumulates evidence of past aversive experiences over minutes to generate a scalable behavioral state consisting of multiple behavioral changes. Using a brain-wide imaging screen, we identified a set of neurons that integrate aversive sensory stimuli over different timescales, from seconds to minutes. Neuronal perturbations show that these integrator neurons are critical for the aversive behavioral state. They control distinct behavioral features, such as changes in locomotion speed or increased responsiveness to subsequent aversive stimuli. Moreover, the integrator neurons function in parallel to one another, utilize different mechanisms to generate persistent neural activity, and signal through different transmitters. Our result show how a behavioral state can be decomposed into distinct behavioral features that map onto different neural integrators that act in parallel. Combined action of the integrators then generates the full set of behaviors that comprise the global state.

neuroscience↗