Biology subjects

Yoo, J.

Publications and source records attributed to Yoo, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Circular Data Analysis for Spatial Omics

Many biological quantities in omics are inherently periodic or directional, including circadian phase, cell-cycle position, and cellular orientation. Treating such quantities as ordinary linear variables can introduce artificial discontinuities and obscure biological interpretation. Circular methods are well developed across directional statistics, bioinformatics, and spatial statistics, but practical guidance for omics applications remains limited. We present key considerations for circular data analysis in single-cell and spatial omics, including the provenance and observational unit of the circular quantity, the inferential or predictive objective, the distinction between tissue composition and residual spatial dependence, and the choice of appropriate models. We describe relevant approaches for circular representation, inference, clustering, regression, machine learning, and spatial analysis, together with representative R software. Their practical use is illustrated through spatial transcriptomic case studies of derived circadian peak phase in a mouse model of Alzheimer's disease and latent cell-cycle position in human ovarian cancer. These examples demonstrate how the definition of the angle, its observational unit, and tissue heterogeneity shape appropriate analysis and interpretation, including when spatial modeling is not warranted. We conclude with practical recommendations and directions for future methodological development.

bioinformatics↗

bioRxiv2026

Intra-uterine position modulates lifelong hippocampal neurogenesis and anxiety-related behavior

Individual differences in vulnerability to disease are a defining feature of biology and are especially prominent in mood disorders, where susceptibility to stress varies markedly across individuals. Strikingly, such individuality also emerges in inbred mice despite genetic homogeneity and controlled environments, suggesting that early non-genomic factors can durably shape behavioral trajectories. Yet the developmental origin of this variability remains largely unknown. Here, we identify the intra-uterine position (IUP) as a potent source of inter-individual variability in emotional behavior by showing that it influences prenatal steroid exposure, hippocampal development, adult neurogenesis, and anxiety-like traits in inbred mice. At embryonic day 18.5, embryos adjacent to one or two male siblings (i.e. 1M/2M) exhibited altered brain steroid profiles, coinciding with increased proliferation of neural stem and progenitor cells in the dentate gyrus, as compared to 0M mice. Single-nucleus RNA sequencing further revealed that IUP leaves a transcriptional imprint on hippocampal development, with 1M/2M neural stem cells showing reduced stemness and activation of a neurogenic transcription program. In adulthood, 1M/2M mice presented reduced hippocampal and dentate gyrus volumes, diminished radial-glia-like cell counts, lower cell proliferation, and impaired dendritic maturation of immature neurons. Behaviorally, both juvenile (PND22) and young adult (8-week) 1M/2M mice displayed increased trait anxiety, and 1M/2M males exhibited heightened stress reactivity. In vitro, testosterone, but not progesterone, directly enhanced proliferation of adult rat hippocampal stem/progenitor cells, whereas corticosterone reduced it. In vivo, administration of the androgen receptor agonist dihydrotestosterone (DHT) to pregnant dams recapitulated IUP effects by increasing embryonic dentate gyrus (DG) proliferation in female embryos, whereas antagonism reduced progenitor proliferation in male embryos. Together, these results indicate that IUP has long-lasting effects on hippocampal development and anxiety and may underlie natural variations in trait anxiety.

neuroscience↗

bioRxiv2026

Longitudinal transcriptomic analysis reveals adaptive transcript usage remodeling associated with PARP inhibitor resistance

Poly (ADP-ribose) polymerase inhibitors (PARPi) have revolutionized the treatment of ovarian and breast cancers with homologous recombination deficiency (HRD). Despite substantial initial efficacy, the frequent development of acquired resistance poses a critical clinical challenge, necessitating a deeper understanding of the underlying molecular mechanisms. While genomic profiling provides information on baseline HRD status, it is insufficient to capture the dynamic and functional adaptations accompanying resistance during treatment. In this study, we investigated the role of alternative splicing in PARPi resistance using longitudinal pre- and post-treatment RNA-sequencing data from an ovarian cancer patient cohort (n=40). We demonstrated that profiling alternative splicing dynamics and differentially used transcripts (DUTs) provides transcriptomic insights distinct from conventional differential gene expression analysis. Notably, we observed significant differences between acquired resistance (AR) and innate resistance (IR) groups. Specifically, longitudinal analysis revealed that AR tumors exhibit a distinct transcript usage pattern, characterized by an increase in canonical protein-coding transcripts involved in cell-cycle processes and a decrease in non-canonical non-coding transcripts within the homologous recombination pathway following treatment. Extending this comparison across AR and IR tumors at both pre- and post-treatment stages, these transcriptomic features were most pronounced in the AR post-treatment group. Further analysis of subsequent treatment outcomes showed that, among AR patients, greater resistance-associated transcriptomic remodeling was associated with poorer response and shorter progression-free survival. The resistance-associated transcriptomic signatures identified through longitudinal profiling were further recapitulated in an independent pre-treatment cohort (n=71; 43 AR and 28 IR), with more pronounced differences among BRCA wild-type patients. Taken together, our findings identify differential transcript usage as dynamic transcriptomic features associated with acquired PARPi resistance and establish a framework for utilizing longitudinal transcriptome dynamics to investigate the molecular basis of clinical drug resistance.

cancer biology↗

bioRxiv2026

A pleiotropic EPAS1 enhancer mediating Tibetan adaptation to hypoxia is active in adipocytes

In response to hypoxic stress at high altitudes, variation at the EPAS1 locus has experienced strong selection in Tibetans. Functional dissection of the selection signals at this locus identified ENH5, an enhancer within the adaptive haplotype that has a blunted response to hypoxic stress in Tibetans. ENH5 was shown to be pleiotropic in several tissues related to hypoxia response, suggesting that a possible mechanism behind the strong selection signatures could be adaptive pleiotropy. Tibetans not only experience hypoxic conditions, but also cold temperatures due to the altitude and climate of the Tibetan Plateau. However, it is unclear whether cold temperatures affect ENH5 activity possibly contributing to the selective pressure at this locus. Here, we further characterized the role of ENH5 in subcutaneous white adipose tissue, an important tissue type that regulates body temperature in response to cold temperatures by releasing stored fat as heat through a process called thermogenesis. In this work, we investigated the role of ENH5 in adipocytes using ENH5 knockout mice (ENH5 KO), which phenocopy the reduced activity of the Tibetan allele. We show that ENH5 KO mice at normoxia and room temperature do not have significant differences in organismal phenotypes related to adiposity and metabolism compared to WT mice on a high fat diet. However, we detected effects of ENH5 conditional on thermogenic stimulation and hypoxia exposure, independently, in adipocytes cultured in vitro. Under either of these conditions, ENH5 KO has stronger differential expression of key genes involved in thermogenesis activity and adipocyte differentiation compared to WT. This differential response to thermogenic stimulation expands on the pleiotropic effects of the Tibetan ENH5 allele(s), in addition to those previously shown in well-established hypoxia-responsive tissues. Our results raise the possibility that pleiotropic effects of ENH5 may implicate unforeseen mechanisms, such as cellular energetics and thermogenesis, possibly contributing to the phenotypic adaptation to high altitude in Tibetans.

genetics↗

bioRxiv2026

Title: Zero-shot automated insulin delivery for type 1 diabetes via dynamic physiology-aware reinforcement learning

Insulin therapy in type 1 diabetes requires constant dose adjustment based on blood glucose, meals, physiological states, and physical activity. This demanding self-management imposes a substantial burden and increases dosing-error risk, underscoring the need for automated insulin delivery (AID) systems that reduce user intervention. However, many current systems depend on fixed, individualized parameters and may not fully adapt to rapid or unobserved physiological changes. We developed the Dynamic Physiology-Aware Reinforcement learning Controller (DPARC), a zero-shot insulin optimizer that infers latent physiological dynamics from recent continuous glucose monitoring (CGM) and insulin-delivery history without prior personalization, carbohydrate announcements, or preset subject-specific parameters. DPARC uses a rolling 24-hour CGM and insulin-history window, but closed-loop operation can begin after 1 hour of observed data by initializing unobserved history with neutral normalized padding and progressively replacing it with observations. In silico, a single frozen DPARC policy adapted within 1 hour, improved time in range compared with a total daily insulin-conditioned reinforcement learning baseline, and approached the upper-bound performance of a fully personalized model under stochastic unannounced meals with randomized timing, carbohydrate amounts, absorption variability, and meal skipping. In supervised porcine studies under unannounced meals, DPARC maintained high time in range without manual configuration, supporting large-animal feasibility while prospective human evaluation is needed before clinical efficacy can be established. Learned latent representations correlated with physiological markers including insulin sensitivity and plasma insulin concentration, supporting physiological alignment and explanatory anchors. Collectively, these findings support DPARC as a preclinical proof-of-concept zero-shot AID framework for future supervised human evaluation.

bioengineering↗

bioRxiv2026

NGFR/Ngfr-marked basal duct progenitors drive ductal--acinar regeneration in injured salivary glands

Severe salivary gland injury can cause chronic xerostomia and persistent secretory dysfunction, yet the epithelial populations that support repair remain poorly defined. Here, we identify NGFR/Ngfr as a conserved surface marker for isolating organoid-forming epithelial stem/progenitor cells from human and mouse salivary glands and show that mouse Ngfr-lineage cells contribute to ductal-acinar regeneration after injury. Single-cell transcriptomic analysis of human salivary gland tissue identified a restricted NGFR-expressing basal duct epithelial subpopulation with progenitor-like features and early positions along inferred epithelial differentiation trajectories. Functionally, NGFR-expressing cells showed enhanced primary and secondary organoid-forming capacity, and NGFR-enriched human organoids engrafted after transplantation into injured salivary glands of immunodeficient mice. In mouse salivary glands, isolated Ngfr-expressing cells showed enriched organoid-forming activity, and Ngfr expression localized to injury-associated ductal regions after duct ligation and local inflammatory injury. Ngfr-CreERT2 lineage tracing further showed that Ngfr-lineage cells contribute to ductal and acinar compartments during post-injury regeneration. Together, these findings establish NGFR/Ngfr as a conserved surface marker for prospectively isolating basal duct epithelial stem/progenitor populations with organoid-forming activity and injury-responsive ductal-acinar regenerative potential.

cell biology↗

bioRxiv2026

Co-limitation by stable, dynamic and directional habitat features shapes climate vulnerability in an alpine specialist

Alpine ecosystems are among the most climate sensitive on Earth, yet logistical challenges and detection biases often impede robust assessment of alpine dependent species. We investigated habitat associations and density patterns of the Sierra Nevada subspecies of the Gray-crowned Rosy-Finch (Leucosticte tephrocotis dawsoni), an alpine obligate and regional endemic, over five breeding seasons from 2018 to 2022 using hierarchical distance sampling and mark-recapture distance sampling to explicitly account for imperfect detection and spatial heterogeneity. Density estimates tracked annual snowpack variation, ranging from 4.77 individuals/km{superscript 2} in a low snow year to 12.08 individuals/km{superscript 2} in a high snow year. Abundance was highest near persistent snow patches that provide foraging habitat and near cliffs that provide nesting substrate, and declined sharply above approximately 10% woody cover, with densities approaching zero beyond approximately 25%, indicating a steep ecological threshold. In contrast, the proportion of surveyed blocks with detections remained relatively stable across years. Together, these patterns indicate a three timescale co-limitation framework in which breeding habitat is shaped by static features (cliffs), dynamic annual drivers (snowpack), and longer-term directional change (woody encroachment). By linking population density to climate sensitive habitat features, this study provides a high-resolution abundance-based baseline for long term monitoring and offers a framework for evaluating climate vulnerability in alpine and other resource-limited systems. Open Research StatementData necessary to replicate the analyses and results presented in this manuscript will be archived in the Dryad Digital Repository upon acceptance, with no embargo on the material. The R code associated with this manuscript is not novel. All analyses use publicly available packages and functions without modification, including mrds (v2.3.0), unmarked (v1.2.5), tidyverse (v2.0.0), MuMIn (v1.47.5), and standard ggplot2 visualization tools. All code is properly cited within the manuscript and publicly available through CRAN. Complete analysis scripts will be archived in Dryad alongside the data upon acceptance to facilitate full reproducibility of results.

ecology↗

bioRxiv2026

A transcriptomic axis aligns with in vivo functional dynamics in hippocampal inhibitory circuits

Linking molecular identity to function in vivo at single-cell resolution remains an outstanding challenge in neuroscience. Here, we bridge this gap in the mouse hippocampus with an end-to-end pipeline of cell-resolved two-photon imaging and spatial transcriptomics. CA1 interneurons exhibiting heterogeneous physiological responses during a virtual-reality navigation task were post hoc clustered by gene expression into 5 GABAergic subclasses and 14 types. Physiological responses of individual cells aligned with a transcriptomic axis, and a classifier trained on physiological features alone recovered the same ordered organization. Our approach establishes a direct, scalable framework for linking in vivo circuit dynamics to constituent cell identity, revealing a transcriptomic axis that encompasses the structural and functional diversity of hippocampal inhibitory neurons. One-Sentence SummaryTracking neurons from behavior to spatial transcriptomics links in vivo function to molecular identity in the hippocampus.

neuroscience↗

bioRxiv2026

MOZAIC: Compound Growth via In Silico Reactions and Global Optimization using Conformational Space Annealing

MotivationFragment-based drug discovery (FBDD) is an efficient strategy that leverages small molecular fragments to explore broader chemical space by combining them. Advances in computational methods have enabled the calculation of molecular properties and docking scores, thereby accelerating the development of algorithm- and AI-based approaches in FBDD. However, it should be noted that certain methods do not provide synthetic pathways to obtain the proposed compounds. Consequently, these molecules might not be synthesized easily. ResultsIn light of these developments, we propose MOZAIC, a novel framework that explores chemical space using a reaction-based fragment growing and Conformational Space Annealing, a powerful global optimization algorithm. Our results show that MOZAIC effectively produces chemically diverse molecules with balanced improvements in lead-like properties, including QED, synthetic accessibility, and binding affinity. Furthermore, its flexible objective function allows fine-tuning for specific design goals, such as enhancing solubility with binding affinity. These capabilities position MOZAIC as a valuable platform for advancing fragment-to-lead and lead optimization efforts in drug discovery. Availability and implementationMOZAIC is available at https://github.com/kucm-lsbi/MOZAIC/. Supplementary InformationSupplementary data are available at Bioinformatics online.

bioinformatics↗

bioRxiv2026

Identification of Lupus Immune Complex-Driven Pathogenic Pro-inflammatory Monocytes and Macrophages in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE or lupus) is an autoimmune disease characterized by anti-nuclear antibody (ANA) production and inflammation, though the mechanisms by which ANAs induce inflammation and tissue injury are incompletely understood. Here, we identified distinct subsets of mononuclear phagocytes (MPs), including monocytes (Mo) and macrophages (M{Phi}), driven by lupus immune complex (IC), comprised of ANAs and their target antigens. scRNA-seq of human Mo incubated with U1-snRNP (snRNP) lupus IC revealed expansion of distinct pro-inflammatory Mo subsets with upregulation of inflammatory genes including those encoding cytokines, NLRP3, and transcription factors. These transcriptomic changes strongly correlated with protein expression, as determined by proteomic analysis. Mo developed similar pro-inflammatory transcriptomic changes in response to other lupus ICs containing anti-dsDNA and Ro60 antibodies. Interrogation of scRNA-seq datasets from the skin, kidney, and peripheral blood of lupus patients revealed the presence and expansion of pro-inflammatory Mo and M{Phi} populations exhibiting transcriptomic signatures similar to those observed in lupus IC-stimulated Mo. Some of these cells expressing the snRNP IC gene signature exhibited low expression of the type I IFN signature, suggesting that lupus IC and type I IFN signaling may independently affect Mo subsets. In lupus nephritis, infiltration of CD68+ M{Phi} expressing NLRP3 was associated with treatment outcomes. Inhibiting activation of the transcription factor ETS2, a master regulator of Mo/M{Phi}-driven inflammation, attenuated lupus IC-induced activation of pro-inflammatory Mo. Collectively, these findings provide novel insights into the role of lupus IC-driven pro-inflammatory MPs in the pathogenesis of SLE and highlight their relevance as therapeutic targets. Significance StatementSystemic lupus erythematosus (SLE or lupus) is a multi-systemic autoimmune inflammatory disease characterized by anti-nuclear antibody (ANA) production. Lupus immune complex (IC), consisting of ANAs and their target antigens, likely play a critical role in the pathogenesis of lupus through activation of mononuclear phagocytes (MPs), including monocytes (Mo) and macrophages (M{Phi}), which can produce an array of inflammatory molecules. Using transcriptomic and proteomic analyses, our study identified distinct pro-inflammatory Mo populations driven by lupus IC, along with expansion of similar pro-inflammatory Mo and M{Phi} subsets in the skin, kidneys, and peripheral blood of lupus patients. These findings provide novel insights into the pathogenic role of lupus IC-driven pro-inflammatory MPs and support a scientific rationale for therapeutically targeting these cells. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=155 HEIGHT=200 SRC="FIGDIR/small/700902v2_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@1839430org.highwire.dtl.DTLVardef@175dd1dorg.highwire.dtl.DTLVardef@107b54forg.highwire.dtl.DTLVardef@11096b0_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

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

Establishing a continuum of cell types in the visual cortex

The mammalian cerebral cortex is composed of neurons whose properties vary in a continuous fashion rather than falling into discrete cell types. In the mouse visual cortex, excitatory neurons in layer 2 and 3 (L2/3) form such a continuum along cortical depth, patterned by the graded expression of hundreds of genes. Here we sought to understand how this continuum develops and contributes to cortical wiring. Using single-nucleus multiomics (RNA- and ATAC-Seq) and spatial transcriptomics, we show that the L2/3 continuum is established in two phases. During the first postnatal week, a genetically hardwired program establishes a primitive continuum of cell identities spanning the depth of L2/3. The second program, promoted by visual experience, is later superimposed upon the preexisting continuum. This second phase is driven by activity-regulated transcription factors that drive the L2/3 depth-dependent expression of genes linked to synaptic function and plasticity. We show that neurons at different positions along the L2/3 continuum project preferentially to distinct higher visual areas and that visual deprivation disrupts targeting to some higher visual areas while sparing others. Thus, cortical continua emerge through a stepwise process in which genetic programs and sensory experience specify neuronal identity and sculpt intracortical wiring specificity.

neuroscience↗

bioRxiv2025

Breeding Males, But Not Females, Have Elevated Androgen Receptor Expression in the Northern House Wren (Troglodytes Aedon), a Temperate Songbird with Female Song

In many male temperate-breeding songbirds, increased plasma testosterone in the early breeding season regenerates song control nuclei that regulate song. Females of some temperate species also sing but have lower circulating testosterone concentrations. We hypothesized that upregulation of steroid receptors in females could compensate for low circulating testosterone, focusing on the northern house wren (Troglodytes aedon), a temperate-breeding songbird in which both sexes sing. We collected brain tissue from both sexes during the early breeding, late breeding, and nonbreeding season. Using quantitative PCR, we quantified mRNA expression of four genes--androgen receptor (AR), estrogen receptors (ER and ER{beta}), and aromatase (AROM)--in three song nuclei--HVC, Area X, and RA--and compared sexes. We found females had lower expression than males of AR, AROM and ER in most song nuclei, especially of AR in HVC in the breeding season. Both sexes, however, had low ER expression in Area X and RA. In males, expression differed seasonally: breeding males had higher expression of AR in RA and AROM in HVC than nonbreeding males. In both sexes, expression differed among song nuclei: in most genes, HVC had the highest expression, followed by RA, then Area X. These findings suggest singing female house wrens do not compensate for low plasma testosterone by upregulating steroid receptors beyond male levels or during early breeding, when they sing most. Conversely, increased AR expression in breeding males indicates differences in the mechanisms regulating male and female song, with testosterone playing a greater role in male birdsong.

animal behavior and cognition↗

bioRxiv2024

IDH-mutant gliomas arise from glial progenitor cells harboring the initial driver mutation

Discovering the cell-of-origin harboring the initial driver mutation provides a fundamental basis for understanding tumor evolution and development of new treatments. For isocitrate dehydrogenase (IDH)-mutant gliomas - the most common malignant primary brain tumors in adults under 50 - the cell-of-origin remains poorly understood. Here, using patient brain tissues and genome-edited mice, we identified glial progenitor cells (GPCs), including oligodendrocyte progenitor cells (OPCs), as the glioma-originating cell type harboring the IDH mutation as the initial driver mutation. We conducted comprehensive deep sequencing, including droplet digital PCR and deep panel and amplicon sequencing to 128 tissues from 62 patients (29 IDH-mutant gliomas and 33 IDH-negative controls) comprising tumors, normal cortex or normal subventricular zone (SVZ), and blood. Surprisingly, low-level IDH mutation was found in the normal cortex away from the tumor in 38.5% (10 of 26) of IDH-mutant glioma patients, whereas no IDH mutation was detected in the normal SVZ. Furthermore, by analyzing cell-type-specific mutations, the direction of clonal evolution, the single-cell transcriptome from patient brains and novel mouse model of IDH-mutant glioma arising from mutation-carrying OPCs, we determined that GPCs, including OPCs, harboring the initial driver mutation are responsible for the development and evolution of IDH-mutant gliomas. In summary, our results demonstrate that GPCs containing the IDH mutation are the cells-of-origin harboring the initial driver mutation in IDH-mutant gliomas.

cancer biology↗

bioRxiv2024

Human-specific paralogs of SRGAP2 induce neotenic features of microglia structural and functional maturation

Microglia play key roles in shaping synaptic connectivity during neural circuits development. Whether microglia display human-specific features of structural and functional maturation is currently unknown. We show that the ancestral gene SRGAP2A and its human-specific (HS) paralogs SRGAP2B/C are not only expressed in cortical neurons but are the only HS gene duplications expressed in human microglia. Here, using combination of xenotransplantation of human induced pluripotent stem cell (hiPSC)-derived microglia and mouse genetic models, we demonstrate that (1) HS SRGAP2B/C are necessary and sufficient to induce neotenic features of microglia structural and functional maturation in a cell-autonomous manner, and (2) induction of SRGAP2-dependent neotenic features of microglia maturation non-cell autonomously impacts synaptic development in cortical pyramidal neurons. Our results reveal that, during human brain evolution, human-specific genes SRGAP2B/C coordinated the emergence of neotenic features of synaptic development by acting as genetic modifiers of both neurons and microglia.

neuroscience↗

bioRxiv2023

Comparison of the mechanism of antimicrobial action of the gold(I) compound auranofin in Gram-positive and Gram-negative bacteria

The antirheumatic gold(I) compound auranofin has been suggested to exhibit bactericidal activity by disrupting the thiol homeostasis through direct inhibition of bacterial thioredoxin reductase (TrxB). While highly effective at killing Gram-positive bacteria, it lacks significant activity against Gram-negative species for reasons that largely remain unclear. Here, we aimed to elucidate the molecular mechanisms underlying the low susceptibility of the Gram-negative model organism Escherichia coli to auranofin when compared to the Gram-positive model organism Bacillus subtilis. A change in the proteome of E. coli exposed to auranofin suggested that the effect of this gold compound is a combination of inactivation of thiol-containing enzymes, upregulation of proteins involved in basal metabolism, and the consequent induction of systemic oxidative stress. Susceptibility tests in E. coli mutants lacking the proteins upregulated upon auranofin treatment suggested that none of them are directly involved in E. colis high tolerance to auranofin. To elucidate factors that could make Gram-negative bacteria less susceptible to auranofin, we tested E. coli cells lacking the efflux pump component TolC. These cells were more sensitive to auranofin treatment than the wild type, but not to an extent that would fully explain the observed difference in susceptibility of Gram-positive and Gram-negative organisms. We thus tested if E. colis thioredoxin reductase (TrxB) is inherently less sensitive to auranofin than TrxB from B. subtilis, which was not the case. E. coli cells lacking components of the thioredoxin-system were also only marginally more susceptible to auranofin. However, E. coli strains lacking the low molecular weight thiol glutathione, but not glutathione reductase, showed a high susceptibility to auranofin. Bacterial cells expressing the genetically encoded redox probe roGFP2 allowed us to observe the oxidation of cellular protein thiols in situ. In line with their susceptibility, the kinetics of probe oxidation and the degree of oxidation promoted by auranofin is significantly higher in Gram-positive bacteria when compared to Gram-negative bacteria. Based on our findings, we hypothesize that auranofin leads to a global disturbance in the cellular thiol redox homeostasis in bacteria, but Gram-negative bacteria are inherently more resistant due to the presence of drug export systems and high cellular concentrations of glutathione.

biochemistry↗

bioRxiv2023

Mapping of multiple neurotransmitter receptor subtypes and distinct protein complexes to the connectome

Neurons express different combinations of neurotransmitter receptor (NR) subunits and receive inputs from multiple neuron types expressing different neurotransmitters. Localizing NR subunits to specific synaptic inputs has been challenging. Here we use epitope tagged endogenous NR subunits, expansion light-sheet microscopy, and EM connectomics to molecularly characterize synapses in Drosophila. We show that in directionally selective motion sensitive neurons, different multiple NRs elaborated a highly stereotyped molecular topography with NR localized to specific domains receiving cell-type specific inputs. Developmental studies suggested that NRs or complexes of them with other membrane proteins determines patterns of synaptic inputs. In support of this model, we identify a transmembrane protein associated selectively with a subset of spatially restricted synapses and demonstrate through genetic analysis its requirement for synapse formation. We propose that mechanisms which regulate the precise spatial distribution of NRs provide a molecular cartography specifying the patterns of synaptic connections onto dendrites.

neuroscience↗

bioRxiv2023

In vitro broad-spectrum antiviral activity of MIT-001, a mitochondria-targeted reactive oxygen species scavenger, against severe acute respiratory syndrome coronavirus 2 and multiple zoonotic viruses

The COVID-19 pandemic caused by SARS-CoV-2 becomes a serious threat to global health and requires the development of effective antiviral therapies. Current therapies that target viral proteins have limited efficacy with side effects. In this study, we investigated the antiviral activity of MIT-001, a small molecule reactive oxygen species (ROS) scavenger targeting mitochondria, against SARS-CoV-2 and other zoonotic viruses in vitro. The antiviral activity of MIT-001 was quantified by RT-qPCR and plaque assay. We also evaluated the functional analysis of MIT-001 by JC-1 staining to measure mitochondrial depolarization, total RNA sequencing to investigate gene expression changes, and immunoblot to quantify protein expression levels. The results showed that MIT-001 effectively inhibited the replication of B.1.617.2 and BA.1 strains, Zika virus, Seoul virus, and Vaccinia virus. Treatment with MIT-001 restored the expression of heme oxygenase-1 (HMOX1) and NAD(P)H: quinone oxidoreductase 1 (NqO1) genes, anti-oxidant enzymes reduced by SARS-CoV-2, to normal levels. The presence of MIT-001 also alleviated mitochondrial depolarization caused by SARS-CoV-2 infection. These findings highlight the potential of MIT-001 as a broad-spectrum antiviral compound that targets for zoonotic RNA and DNA viruses, providing a promising therapeutic approach to combat viral infection.

microbiology↗