Biology subjects

Kim, J.

Publications and source records attributed to Kim, J..

At least 181 records · Page 10Linked to original sources

bioRxiv2026

Scalable high-fidelity human vascularized cortical assembloids recapitulate neurovascular co-development and cell specialization

Human cortical development involves the coupling of neurogenesis and cerebrovascular growth. However, interactions between neural and vascular cells are largely missing in most brain organoids, which are crucial models for studying neurodevelopment and disease. Here, we establish vascularized cortical assembloids (vCAs) by fusing mesoderm-derived vascular organoids (VOs) with cortical organoids (COs). vCAs self-assemble lumenized networks of endothelial cells, pericytes, and perivascular fibroblasts that acquire blood-brain barrier (BBB) specialization and arteriovenous specification in vitro. Single-cell RNA-sequencing and immunofluorescence imaging revealed that vascularization improves neuroepithelial architecture, reduces hypoxia and apoptosis, expands cortical progenitor pools, and enhances neuronal maturation and connectivity compared with COs. Moreover, atlas-level integration with human neurodevelopmental tissue and cross-protocol benchmarking demonstrate superior transcriptional concordance, especially for vascular cell and glial populations, relative to existing approaches. This scalable and reproducible platform improves fidelity and throughput for modeling human neurovascular co-development and enables systematic studies across brain regions and diseases using engineered or patient-derived iPSCs.

developmental biology↗

bioRxiv2026

Metabolite mimicry identifies butyrate analogs with select protective functions in the intestinal mucosa

Microbial-derived short-chain fatty acids regulate a variety of pathways in the healthy colonic mucosa. In particular, butyrate serves as the primary energy source for colonocytes and regulates gene transcription by stabilizing the transcription factor hypoxia-inducible-factors (HIF) and functioning as a histone deacetylase (HDAC) inhibitor. A limitation of butyrate as a therapeutic is its rapid metabolism in differentiated colonocytes. Furthermore, intestinal stem cells (ISCs) respond differently to butyrate, preferentially using glucose for energy procurement. To address these limitations, we explored metabolite-mimicry to discover compounds with potent or selective biological responses within the butyrate pathway(s). We discovered an analog, 3-chlorobutyrate (3-Cl BA), that significantly enhances epithelial barrier formation and wound healing in vitro. Mechanistically, we revealed that 3-Cl BA is a potent HDAC inhibitor. Furthermore, unlike butyrate, 3-Cl BA does not stabilize HIF and it is not used as metabolic fuel. In vivo studies in a DSS-colitis model revealed that contrary to butyrate, 3-Cl BA is protective. Studies in stem-like colonoids demonstrated that only butyrate inhibits ISC proliferation and differentiation. Furthermore, it was recently reported that HIF stabilization inhibits ISCs activity. Given the fact that butyrate but not 3-Cl BA stabilizes HIF, we surmised that 3-Cl BA would circumvent these detrimental functional consequences. We demonstrate here that pharmacologic HIF stabilization inhibits colonoid differentiation and that genetic loss of HIF significantly promotes ISC differentiation. This study reveals a promising butyrate analog protective in colitis and demonstrates the advantages of metabolite-mimicry to dissect selective biological functions from major metabolites in the gut. Significance statementButyrate is a well-studied microbial short-chain fatty acid that regulates a number of mucosal pathways and is paramount in maintaining intestinal integrity. In health, it is a major source of energy for colonocytes and regulates gene transcription. The role of butyrate in disease is still controversial and not well understood. When butyrate is not metabolized or well-utilized (e.g. disease), it accumulates in intestinal stem cells leading to reduced cell proliferation and differentiation, thereby hampering intestinal barrier recovery. In this study, we describe a butyrate analog that enhances epithelial barrier formation and wound healing. Furthermore, as opposed to native butyrate, this butyrate analog is protective in a colitis mouse model and does not exhibit detrimental influences on intestinal stem cells. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/697087v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1dd0f0borg.highwire.dtl.DTLVardef@6d27forg.highwire.dtl.DTLVardef@1e5d07corg.highwire.dtl.DTLVardef@dab74f_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO Microbially derived butyrate plays a key role in intestinal homeostasis. It is the primary source of energy for colonocytes, contributing to a metabolic and oxygen gradient as it is metabolized by differentiated cells along the intestinal crypt. Through the regulation of transcription factors such as HIF and the inhibition of HDAC, it regulates barrier formation and wound healing promoting a strong tight junction profile. Furthermore, well oxygenated ISCs at the bottom of the crypt are unaccustomed to the effects of butyrate, including HIF stabilization (left). In disease, loss of intestinal architecture leads to a disrupted metabolic/oxygen gradient where butyrate accumulates in stem cells leading to decreased proliferation, differentiation, and increases in apoptosis. 3-Cl BA selectively acts as an HDACi and does not stabilize HIF, exhibiting no significant detrimental effects on ISCs (right). Created in BioRender. Ornelas, A. (2026) https://BioRender.com/x9cy8mw C_FIG

molecular biology↗

bioRxiv2026

HSF1-dependent, long-range directional HSPA1 gene motion to nuclear speckles is coupled to DDX39B condensate dynamics

Approximately 5-10% of the genome, enriched [~]10-fold in the most highly active genes, positions near deterministically within several hundred nm of nuclear speckles (NS). This includes the HSPA1 locus, among the most strongly NS-associated genes. Here we address how HSPA1 endogenous genes and transgenes stably position adjacent to the nuclear speckle periphery, facilitating their gene expression amplification. Live-cell imaging demonstrates a transcription-dependent speckle-anchoring of HSPA1 genes. Removal of this anchoring reveals sustained, long-range, curvilinear oscillations of the HSPA1 genes away from and back to nuclear speckles or between nuclear speckles. Curvilinear transgene movements are dependent on the transcription factor HSF1, largely independent of nuclear actin or cohesin, but unexpectedly spatially and temporally correlated with DDX39B condensate dynamics and dependent on DDX39B protein levels. We propose that stable nuclear speckle association of HSPA1 results from combining metastable speckle anchoring with constitutive, restorative long-range chromosome movements driven by DDX39B condensate dynamics.

cell biology↗

bioRxiv2026

The Extracellular Matrix Regulates Invasion in Fusion-Negative Rhabdomyosarcoma via YAP-PIEZO1 Signaling Axis

BackgroundFusion-negative rhabdomyosarcoma (FNRMS) represents the most prevalent subtype of rhabdomyosarcoma, the most common pediatric soft tissue sarcoma. Although its invasion is a leading cause of recurrence and poor prognosis, its underlying mechanism remains unclear. We investigated how extracellular matrix (ECM) density regulates FNRMS progression via mechano-transduction. MethodsWe used three-dimensional spheroid invasion assays with RD and SMS-CTR cells embedded in varying collagen concentrations. Mechanistic insights were gained through immunofluorescence, ChIP-seq re-analysis, Fluo-4 calcium live cell imaging, and pharmacological inhibition of the YAP-PIEZO1 axis. ResultsHigh ECM density significantly enhanced invasive spreading, correlating with increased YAP nuclear localization. YAP overexpression was sufficient to promote invasion, while its inhibition attenuated the matrix-enhanced phenotype. We identified PIEZO1 as a direct transcriptional target of the YAP. High ECM density stimulated PIEZO1-dependent calcium influx, which was required for invasion. Furthermore, elevated PIEZO1 expression was significantly associated with poorer overall survival in FNRMS patients. Targeting YAP or ROCK signaling effectively suppressed both calcium flux and invasion. ConclusionsOur findings establish a YAP-PIEZO1 axis linking ECM density to FNRMS invasion. This mechanosensitive pathway represents a potential therapeutic vulnerability in aggressive FNRMS. Simple SummaryFusion-negative rhabdomyosarcoma (FNRMS) is the prevalent subtype of rhabdomyosarcoma, the most common pediatric soft tissue sarcoma. Its invasion often leads to recurrence and poor prognosis. This study investigates how the density of the extracellular matrix (ECM), surrounding cancer cells in the tissue, influences FNRMS invasion. We found that high ECM density activates the protein YAP, which directly triggers the expression of the mechanical sensor PIEZO1. This sensor allows calcium to enter the cells, providing a signal that facilitates invasion. Pharmacological inhibition of this axis successfully reduced the invasive potential, highlighting a novel therapeutic vulnerability for FNRMS patients.

cancer biology↗

bioRxiv2026

Neural markers of visual working memory during an upper extremity movement-coupled task: a mobile brain-body imaging (MOBI) study.

Optimal goal-directed behavior in everyday life involves the appropriate coupling of cognition and movement. In this study we employed a mobile brain-body imaging (MoBI) system that integrated time-synchronized high-density electroencephalography with 3-dimensional motion capture during a touchscreen visual working memory task requiring dynamic upper extremity reach responses. Using this framework we examined how increasing memory load (i.e. from 1-disc to 4-discs) influences behavior and scalp-recorded neural activity when cognitive and motor processes are coupled within a single task and whether these effects are modulated by handedness. Increasing memory load reliably degraded working memory task performance and slowed motor preparation, while core movement execution measures remained largely preserved. Regarding electroencephalography data, parieto-occipital activity increased with load during both the early visual-evoked N1 and the delay period. However, load-related modulation reached a plateau at the 3-disc condition during the delay period only. Posterior-frontal engagement also strengthened as load increased, consistent with demands on attentional control, memory maintenance, and sensorimotor planning. Brain-behavior associations were most robust at a moderate level (2-disc), where contralateral delay activity correlated with both cognitive and motor performance measures. Finally, although handedness exerted selective behavioral effects, it did not modulate load-related parieto-occipital neural activity. Together, these findings demonstrate that a multimodal MoBI approach captures integrated cognitive-motor dynamics during working memory-guided actions, providing a more comprehensive characterization of behavior and underlying neural signatures than either modality alone. This framework offers a translational approach for studying cognitive-motor interactions and their potential disruption in neurological conditions such as Parkinsons disease.

neuroscience↗

bioRxiv2025

APE1 Coordinates Its Disordered Region and Metal Cofactors to Drive Genome Surveillance

Efficient recognition of DNA lesions such as apurinic/apyrimidinic (AP) sites is essential for maintaining genome stability. Apurinic/apyrimidinic endonuclease 1 (APE1) is the primary eukaryotic AP endonuclease, yet how it identifies rare lesions among vast stretches of undamaged DNA remains incompletely understood. Using single-molecule imaging combined with molecular dynamics simulations, we reveal that APE1 employs a distinctive dual mechanism to search DNA. First, Mg{superscript 2} coordination at the active site neutralizes clustered negative charges, stabilizing electrostatic contacts during scanning. Second, its N-terminal intrinsically disordered region (IDR)--a feature conserved only in eukaryotic homologs but absent in prokaryotic ExoIII--not only forms DNA through transient IDR contacts but also engages continuous interactions via the unprecedented 177 arginine residue within the structured nuclease domain, thereby prolonging residence time and enabling long-range diffusion. Together, these two modules synergize to promote a sliding-based search strategy tailored to the complexity of eukaryotic genomes. Consistent with this model, IDR deletion restricts APE1 to 3D collisions, whereas IDR duplication enhances 1D scanning. Thus, APE1 exemplifies how structural disorder and metal-ion coordination integrate to enable long-range lesion recognition, highlighting an evolutionary innovation in eukaryotic DNA repair.

molecular biology↗

bioRxiv2025

Large scale prospective evaluation of co-folding across 557 Mac1-ligand complexes and three virtual screens

Accurate prediction of ligand-bound protein complexes and ranking them by affinity are central problems in drug discovery. While deep learning co-folding methods can help address these challenges, their evaluation has been hampered by the difficulties in assessing independence from training data and insufficiently large test sets. Here we test the ability of co-folding methods to predict the structures of 551 ligands, 489 of which are of sufficient quality for evaluation, bound to the SARS-CoV-2 NSP3 macrodomain (Mac1) that were determined after the training cut-off dates. AlphaFold3 (AF3), Boltz-2, and Chai-1 each reproduced >50% of the Mac1 ligand poses to better than 2 [A] RMSD of experiment. Despite the potential for co-folding to describe protein conformational changes that stabilize ligand binding, we did not find that common conformational rearrangements, including peptide flip and a large loop opening, were recapitulated by the co-folding prediction. For AF3 and Chai-1, ligand pose prediction confidence weakly, but significantly, tracked experimental potency, while DOCK3.7 energies were only weakly correlated. Boltz-2 affinity predictions showed the strongest correlation with measured potency and, after calibration, achieved lower mean absolute error than a baseline predictor. We next assessed whether co-folding scores could rescore docking hit-lists to distinguish true ligands from non-binders among hundreds of molecules prospectively experimentally tested against AmpC {beta}-lactamase, the dopamine D4 and the {sigma}2 receptors. AF3 ligand pose confidence values did not separate true ligands from high-scoring false-positives as effectively as docking scores or Boltz-2 affinity predictions did. Taken together, the modest, but independent correlations of docking score and co-folding confidence or affinity suggests that integrating physics-based and deep-learning approaches may help with hit prioritization and subsequent optimization in structure-based ligand discovery.

biophysics↗

bioRxiv2025

Microbiome-host interactions drive a trade-off between sleep quality and lifespan in Drosophila

Understanding the interactions between various aging processes and the resulting heterogeneity in aging is crucial for promoting healthy aging. Here, we provide evidence that heterogeneity in microbiome and host interactions contributes to diversifying aging phenotypes in sleep, gut integrity, and longevity in Drosophila. Aged flies exhibiting sleep fragmentation preserve gut integrity, accompanied by a shift in microbiota composition, particularly an increase in Acinetobacter junii. A. junii induces sleep fragmentation via its metabolite, urocanic acid, through serotonin receptor-dependent dopamine upregulation. In parallel, A. junii exploits the host response to promote its growth, leading to lifespan extension, which is recapitulated by genetically modified Escherichia coli, suggesting a trade-off between sleep quality and lifespan. Our study demonstrates a systematic mechanism underlying aging heterogeneity, suggesting interventions through bacterial supplements.

animal behavior and cognition↗

bioRxiv2025

Chronic alcohol exposure drives inflammaging and transposon derepression in hematopoietic stem and progenitor cells

Chronic alcohol use can cause pancytopenia and diminished immune responses against pathogens. However, its underlying molecular mechanisms remain unclear. Furthermore, whether chronic alcohol consumption directly induces inflammation in human hematopoietic stem progenitor cells (HSPCs) or whether it affects aging hematopoiesis differently is unknown. To examine how chronic alcohol use influences HSPCs, we performed single-cell RNA-seq in murine and human HSPCs and single-cell ATAC-seq in aged murine HSPCs following alcohol exposure. In the native murine bone marrow, chronic alcohol exposure primed HSPCs to differentiate into myeloid cells and to exhibit heightened inflammation, DNA damage, and epigenetic reactivation of transposable elements (TEs) in an age-dependent manner. Alcohol-exposed aged long-term hematopoietic stem cells (LT-HSCs) displayed increased chromatin accessibility at TE-containing loci correlated with aberrant TE transcription. This transposon derepression was associated with the accumulation of dsRNAs in aged bone marrow cells, and activation of innate immune pathways, perpetuating HSC inflammaging. Furthermore, we identified two epigenetically distinct LT-HSC clusters, LT-HSC1 and LT-HSC2, with the LT-HSC2 cluster expanding in response to chronic alcohol consumption, resembling activated HSCs. In xenotransplanted human HSPCs, chronic alcohol feeding resulted in a significant myeloid bias, heightened inflammation, upregulation of double-stranded RNA (dsRNA) sensors, activation of type I interferon responses, and increased expression of endogenous retroviruses. Despite these molecular alterations, we did not observe a decrease in long-term repopulation capacity in either human or murine HSCs. This suggests that HSC function may recover following alcohol cessation. However, previous chronic alcohol exposures imprint murine HSPCs to exhibit long-term myeloid bias and reduced cell cycle entry upon bacterial LPS challenge. Our data illuminate potential interactions between alcohol and aging that can reinforce inflammaging and epigenetic dysregulation in HSPCs. KeypointsO_LIAging perpetuates alcohol-induced myeloid bias, inflammation, DNA damage, and TE upregulation in murine HSPCs C_LIO_LIPrior chronic alcohol consumption does not affect long-term repopulation but causes persistent myeloid bias and inefficient stress responses after LPS challenge C_LIO_LIChronic alcohol consumption alters chromatin accessibility in TE-overlapping regions C_LIO_LIChronic alcohol consumption promotes myeloid bias, inflammation, and upregulation of endogenous retroviruses in xenotransplanted human HSPCs. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/696246v2_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@e0357aorg.highwire.dtl.DTLVardef@1d702fdorg.highwire.dtl.DTLVardef@10553ddorg.highwire.dtl.DTLVardef@c4e62e_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Urolithin A Restores Mitochondrial Function and Reverses Cardiac Remodeling in Heart Failure with Preserved Ejection Fraction

BackgroundHeart failure with preserved ejection fraction (HFpEF) accounts for nearly half of all heart failure cases; however, mechanism-based therapies targeting cellular dysfunction remain absent. Emerging evidence suggests that mitochondrial dysfunction and impaired quality control, particularly defective mitophagy, are central to the pathogenesis of HFpEF. Urolithin A (UA), a gut microbiome-derived postbiotic metabolite, has shown promise as a mitophagy activator in preclinical models; however, its therapeutic efficacy in HFpEF remains unknown. MethodsWe used a clinically relevant two-hit HFpEF mouse model (high-fat diet (HFD) plus N{omega}-nitro-L-arginine methyl ester (L-NAME)) and co-administered UA during disease progression. The cardiac structure and function were assessed using echocardiography, histology, and transmission electron microscopy. Mitochondrial bioenergetics were evaluated using Seahorse-based respirometry. Mitophagy flux was monitored using mt-Keima assays in H9c2 cells and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Mechanistic insights were obtained using immunoblotting, integrated shotgun metagenomic and lipidomic profiling, and single-nucleus RNA sequencing (snRNA-seq). ResultsUA treatment significantly attenuated cardiac remodeling and fibrosis in HFpEF mice while improving diastolic function parameters. Transmission electron microscopy revealed restoration of the mitochondrial ultrastructure, and mitochondrial stress tests demonstrated enhanced oxidative phosphorylation capacity and glycolytic reserves. Immunoblot assays revealed that UA treatment recovered PINK1/Parkin-mediated mitophagy markers (reduced LC3-II and p62/SQSTM1). Mt-Keima assays confirmed enhanced mitophagic flux in H9c2 cells under HFpEF-like stress conditions. Integrated metagenomics and lipidomics revealed significant reductions in cardiovascular risk-associated ceramides. snRNA-seq demonstrated that HFpEF-like stress downregulated contractile, calcium-handling, and mitochondrial mitophagy gene programs. UA treatment restored the mitochondrial quality control signatures and normalized profibrotic and conduction-type cell populations. ConclusionsUrolithin A restored mitochondrial quality control through the activation of mitophagy and reversed cardiac remodeling in HFpEF. These findings establish UA as a mitochondria-targeted therapeutic candidate for HFpEF. Novelty and SignificanceO_ST_ABSWhat is known?C_ST_ABS{checkmark} Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome driven by metabolic stress and myocardial remodeling, for which effective disease-modifying therapies are lacking. {checkmark}Mitochondrial dysfunction and impaired mitophagy have been implicated in HFpEF, but their roles in cardiomyocyte state remodeling and fibrosis remain incompletely defined. {checkmark}Urolithin A, a gut microbiome-derived metabolite, enhances mitophagy in aging and metabolic tissues, but its relevance to HFpEF has not been established. What new information does this article contribute?{checkmark} Urolithin A restores mitochondrial quality control and mitophagic flux in cardiomyocytes, improving diastolic function and attenuating cardiac remodeling in a two-hit HFpEF model. {checkmark}Integrated metagenomic and lipidomic analyses identify suppression of gut microbiome-associated ceramide biosynthesis as a systemic mechanism linked to Urolithin A-mediated cardioprotection. {checkmark}Single-nucleus RNA sequencing reveals that Urolithin A reverses maladaptive cardiomyocyte transcriptional state transitions toward fibrogenic and conduction-like programs.

molecular biology↗

bioRxiv2025

Image-Based Profiling of Induced Trophoblast Stem Cells Identifies Signatures Associated with Sex, Schizophrenia Genomic Risk and Placental Stress

Schizophrenia (SCZ) is a neurodevelopmental disorder where both genetic and environmental risks converge during pregnancy. Recent studies have highlighted the importance of placental biology in influencing risk of developing SCZ. However, the pathways by which genetic risk factors for SCZ interact with environmental influences to alter placental development are poorly understood. Through image-based profiling using Cell Painting, we leveraged trophoblast cultures derived from human induced pluripotent stem cells (hiPSCs) from male and female SCZ and neurotypical donors with varying placental genomic risk scores (PlacGRS) to explore the developmental dynamics of placental cells under normal growth and hypoxic stress. We employed both classical (e.g., CellProfiler) and deep learning feature extraction combined with downstream supervised machine learning to analyze high-dimensional data obtained from this hiPSC-derived model system, highlighting that these approaches overcome the inherent line-to-line variability in phenotypic analysis. Our findings reveal a salient nucleus-localized SCZ risk signature across cell lines, along with clear sexual dimorphism. This research underscores the capability of hiPSC-derived placenta models to elucidate complex interactions between genetic risk and environmental factors implicated in the neurodevelopment of SCZ, paving the way for future studies aimed at developing targeted therapeutic and prevention strategies.

neuroscience↗

bioRxiv2025

Origin and evolution of acrocentric chromosomes in human and great apes

The short arms of human acrocentric chromosomes are characterized by nucleolar organizer regions essential for ribosome biogenesis, but their highly repetitive nature has hindered genomic analysis. Leveraging the recently completed genomes of all major ape lineages, we identified recurrent features of their acrocentrics, including enriched repeat classes, centromere repositioning by whole-arm inversion, interchromosomal sequence exchange, and birth-and-death evolution of multiple gene families. Together, these processes have enabled the repeated amplification and diversification of the FRG1 gene family over 25 million years of ape evolution, and, in gorilla, the formation and amplification of a novel IGSF3-GGT fusion gene under positive selection. Similar evolutionary events also explain the distribution of segmental duplications and heterochromatin in the modern human genome, predisposing it to karyotypic abnormalities such as Robertsonian translocations. Our findings highlight acrocentric chromosomes as key drivers of evolution in the great apes, with implications for speciation, adaptation, and clinical genomics.

genomics↗

bioRxiv2025

Identifying membrane-bound transcriptional regulatory proteins from rare but evolutionarily conserved domain combinations

Transcriptional regulatory proteins, including transcription factors (TFs) and chromatin modifiers, must act inside cell nuclei, but membrane-bound transcription factors (MBTFs) are first anchored in membranes before nuclear translocation. Known MBTFs are vital for processes from myelin expression (MYRF) to cholesterol homeostasis (SREBP), yet their overall diversity remains uncharted. We hypothesized that additional membrane-bound transcriptional regulators (MBTRs) might exist, so we developed a bioinformatics screen to prioritize membrane proteins that are likely to regulate transcription. Our approach leverages domain composition by positing that surprising domain combinations suggest novel biological functions. We searched for rare but evolutionarily conserved pairings of transmembrane domains with domains likely involved in transcriptional regulation. Our method rediscovered known MBTFs and membrane-bound histone kinases, and identified novel MBTR candidates, including transmembrane histone N-acetyltransferases, a putative new subclass of MBTFs that share MYRFs DNA-binding domain, and the prolactin regulatory element-binding protein PREB (SEC12). Assays using recombinant PREB demonstrated that the transmembrane domain is the determinant of PREB subcellular localization, governing its distribution between the membrane and the nucleus in mouse embryonic stem cells. These findings underscore the utility of our method and provide a framework for investigating MBTRs that likely facilitate the integration of extracellular signals with transcriptional responses. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/695554v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@15c71e9org.highwire.dtl.DTLVardef@3aa8e8org.highwire.dtl.DTLVardef@1272f0eorg.highwire.dtl.DTLVardef@18246e1_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

bioRxiv2025

High-Coverage Jomon Genomes Provide Insights into Population Structure and Genetic Traits of Ancient Japanese Hunter-Gatherers

We analyzed eight high-coverage Jomon genomes spanning 9,000-2,800 years ago across the Japanese archipelago. Population genomic analyses revealed substantial genetic homogeneity across time and space reflecting post-glacial isolation, yet temporal stratification emerged: Initial Jomon (Iyai) individuals formed the earliest branch with weaker affinities to present-day Japanese. Using genomes from Todoroki and Chidorikubo sites, we estimated Jomon ancestry in mainland Japanese at [~]20%, substantially higher than previous estimates ([~]13%). Polygenic score analyses, based on the direct analysis of Jomon genomes, provided the genetic evidence for their phenotypic predispositions, including elevated BMI and metabolic trait scores, reduced immune-related scores, and larger cardiac dimensions, patterns consistent with hunter-gatherer adaptations. These ancestral genetic influences, including elevated risks for obesity and dyslipidemia, persist in present-day Japanese. Our findings demonstrate that Jomon populations maintained genetic continuity despite ecological diversity, while their greater-than-expected contribution to present-day Japanese reshapes population history models and reveals how ancient adaptations continue influencing contemporary disease susceptibility.

genomics↗

bioRxiv2025

Master clock-thalamic-prefrontal circuit controls circadian social priority

Social behaviors arise from complex brain operations that adapt to changing social contexts and internal states. However, how internal states guide the resolution of competing social goals remains unclear. Here, we show that prioritization between competing instincts follows a circadian pattern via a circuit linking the suprachiasmatic nucleus (SCN) to the medial prefrontal cortex (mPFC). Specifically, SCNVIP neurons project to Vipr2-expressing neurons in the nucleus reuniens (RE), which innervate the mPFC to regulate social prioritization. Vipr2 signaling in the RE is essential for circadian modulation of appetitive and consummatory social behaviors, aligning social behaviors with clock-regulated reproductive system. Overall, this SCN-RE-mPFC circuit provides a neural principle through which the master clock coordinates the prefrontal cortex to resolve a conflict of motivated behaviors by referencing an internal state.

neuroscience↗

bioRxiv2025

Loss of heterozygosity exposes germline mutations in complex I and drives Warburg metabolism in oncocytic carcinoma of the thyroid

Oncocytic (Hurthle cell) carcinoma of the thyroid (OCT) is characterized by widespread loss of heterozygosity (LOH), mitochondrial accumulation and recurrent mitochondrial DNA mutations leading to impairment of complex I. Here, we establish and characterize a novel OCT cell line, UT946, which displays severe mitochondrial electron transport chain dysfunction and a Warburg metabolic phenotype. Using a series of cytoplasmic hybrids, we establish that the complex I defect in UT946 stems from a nuclear-encoded loss of function mutation in the complex I subunit NDUFS1. To our surprise, the mutation in NDUFS1 was inherited as a recessive germline allele that underwent LOH in the tumor to expose functional loss of complex I. A re-analysis of 91 OCT tumor genomes revealed that LOH-driven exposure of recessive germline mutations in complex I subunits was a recurrent mechanism underlying complex I inactivation in OCT. These findings unveil a new germline-driven mechanism of complex I loss and metabolic reprogramming in cancer, and provide further evidence of the strong selective pressure for complex I impairment in OCT. TeaserGermline mutations in complex I induce aerobic glycolysis in oncocytic carcinoma of the thyroid through somatic loss of heterozygosity.

cancer biology↗

bioRxiv2025

Membrane curvature enhances lipid peroxidation in a composition-dependent manner

Excessive production of reactive oxygen species (ROS) in cells results in oxidative stress, which can promote lipid oxidation in cellular membranes. This oxidation of membrane lipids accompanies various diseases and can even result in cell death through processes such as ferroptosis. The complex compositions and diverse morphologies of cellular membranes make understanding the mechanisms of lipid oxidation challenging, especially when attempting to investigate membrane composition and curvature simultaneously. Here, we utilize reconstituted lipid membranes and the fluorescent oxidation probe C11-BODIPY to quantify oxidation in lipid bilayers as functions of both lipid composition and membrane curvature. By tethering synthetic lipid vesicles to glass substrates, we were able to monitor oxidation of the fluorescent probe on a per vesicle basis using fluorescence microscopy. Our results demonstrate that highly curved membranes markedly increase both the rate and extent of oxidation across diverse membrane compositions. This effect arises from greater exposure of lipid tails to the aqueous environment, which allows more efficient transport of ROS into the hydrophobic core of the bilayer. Compositional effects on oxidation are most pronounced in membranes with low curvature (i.e., greater than 100 nm diameter) and become progressively weaker as curvature increases. We found that low to moderate cholesterol levels (i.e., 10-25 mol%) suppress curvature-dependent oxidation by tightening lipid packing, whereas high cholesterol content (i.e., 50 mol%) restores curvature sensitivity by influencing lateral lipid mobility. Together, these findings establish membrane curvature and lipid composition as interdependent determinants of oxidative susceptibility, offering new insight into how cells regulate or resist oxidative stress. Statement of significanceOxidative stress drives lipid oxidation in cellular membranes, but the combined influence of membrane curvature and composition remains poorly defined. Using reconstituted lipid vesicles and a fluorescent oxidation probe, we show that oxidation in lipid bilayers is enhanced in smaller vesicles (i.e., highly curved membranes). The oxidation rate increases with unsaturated lipids, while cholesterol suppresses this effect. Measurements of membrane packing and diffusivity support these findings, demonstrating how curvature and composition together govern membrane susceptibility to oxidative damage. These results provide new insight into the physicochemical basis of membrane stability under oxidative stress and have broad implications for understanding the vulnerability of curved cellular membranes.

biophysics↗

bioRxiv2025

Subspace clustering identifies transcriptome constraints determining cell type identity

With the advent of single-cell RNA-sequencing, researchers now have the ability to define cell types from large amounts of transcriptome information. Currently, most clustering algorithms measure cell-to-cell similarities using distance metrics based on the assumption that each cluster is comprised of "nearby" neighbors. In effect, clusters are a collection of similar cells in the embedded metric. Here, we propose that biological clusters should be comprised of sets of cells that satisfy a set of stochiometric constraints, whose intersections define a cell type. We propose to model each cell population with a single affine subspace, where all cells of the same type share a common set of linear constraints. We present an algorithm that leverages this subspace structure and learns a cell-to-cell affinity matrix based on notions of subspace similarity. We simulate scRNA-seq data according to the subspace model and benchmark our algorithm against pre-existing methods. We further benchmark our algorithm on a C. elegans dataset and show recovery of information on both cell type and developmental time. Lastly, we find the subspaces that our algorithm recovers allow us to find biologically significant genes involved in an organisms development.

cell biology↗