Biology subjects

Ishii, K.

Publications and source records attributed to Ishii, K..

At least 19 recordsLinked to original sources

bioRxiv2026

Dynamic organizational strategies of multidomain glycosyltransferases revealed by high-speed AFM and solution biophysics

Glycosyltransferases often contain multiple structural modules that contribute to substrate recognition, catalytic coordination, and higher-order molecular organization. However, how multidomain glycosyltransferases dynamically organize their catalytic domains in solution remains poorly understood. Here, we investigated the assembly states and conformational dynamics of POMGNT2, LARGE1, K4CP, and L137 using high-speed atomic force microscopy (HS-AFM) integrated with complementary solution biophysical analyses. POMGNT2 formed a stable dimeric architecture with limited large-scale conformational fluctuation, consistent with its role in site-selective substrate recognition. In contrast, LARGE1 and K4CP exhibited concentration-dependent and heterogeneous assembly behavior. K4CP displayed pronounced open-closed interdomain motion and substrate-dependent conformational compaction, indicating dynamic catalytic-domain reorganization during glycan elongation. By comparison, the mimivirus glycosyltransferase candidate L137 predominantly behaved as a monomeric species under the tested conditions. These findings demonstrate that multidomain glycosyltransferases employ diverse dynamic organizational strategies ranging from rigid recognition architectures to highly flexible and reversible catalytic assemblies. Our results further suggest that glycosyltransferase function is governed not only by catalytic-domain structure, but also by dynamic conformational coordination adapted to distinct catalytic demands.

biophysics↗

bioRxiv2026

Cellular and functional dissection of the octopaminergic system in the Drosophila brain

Octopamine (OA) is a major biogenic amine in the invertebrate nervous system and is often considered a functional analog of vertebrate noradrenaline. Along with its immediate precursor tyramine (TA), OA influences diverse physiological and behavioral processes, including sensory processing and social behavior. However, understanding the neural basis of its multifunctionality has been constrained by the limited genetic access to defined OA/TA neuron types. Here, we present a curated set of transgenic driver strains that provide selective access to nearly all long-range OA/TA cell types in the brain of common fruit flies, Drosophila melanogaster. Using these tools, we map cell-type-specific innervation patterns, compare male and female neuroanatomy, and cross-reference identified neuron types with electron microscopy connectome datasets. As a proof of principle, we show that distinct optic lobe-projecting OA/TA neuron types differentially modulate visually guided behaviors, and we identify a novel OA/TA cell type that suppresses aggression in both sexes. This resource establishes a practical and conceptual foundation for cell-type-resolved analysis of OA/TA circuit function and enables direct integration of genetics, anatomy, and connectomics for studies of neuromodulatory circuit organization.

neuroscience↗

bioRxiv2025

Short-chain fatty acids modulate the development and the cell surface molecule expression of dendritic cells by epigenetic regulation

BackgroundShort-chain fatty acids (SCFAs) are produced by the gut microbiota as secondary metabolites during fermentation process of dietary fibers. Although SCFAs are beneficial for immuno-related diseases because they regulate the gene expression and functions of myeloid cells, the effects of SCFAs on the development of DCs remain unclear. MethodsWe analyzed the effect of SCFAs on the expression levels of surface proteins and mRNAs, and histone modification in Flt3L-induced bone marrow-derived DCs. ResultsSCFAs, particularly butyrate, regulated the expression of surface molecules on mouse bone marrow-derived dendritic cells (DCs): increases in MHCII, CD86, CD11b, and LPAM-1 (4{beta}7) levels and the ratio of CD11c+/PDCA-1-/B220- conventional DCs (cDCs) to CD11c+/PDCA-1+/B220+ plasmacytoid DCs (pDCs). Experiments using inhibitors of histone deacetylase (HDAC) and Gi proteins, and GPR109A deficient mice indicated that butyrate regulated DCs by suppression of HDACs and not through a stimulatory effect on G protein-coupled receptors. Butyrate and the HDAC inhibitor, trichostatin A (TSA), increased the cDC/pDC ratio, surface LPAM-1 and Itga4 mRNA, while the mRNA level of Itgb7 was not affected by butyrate and was reduced by TSA. ChIP assays showed that butyrate and TSA increased histone acetylation in the Itga4 and Spi1 genes. Furthermore, the butyrate treatment increased the levels of Spi1 mRNA and PU.1 protein and decreased those of Spib/SpiB in DCs. In knockdown (KD) experiments using siRNAs, the gene expression of Itga4 was decreased by KD of Spi1 or Irf8, and cDC/pDC ratio decreased by Spi1 KD. ConclusionsButyrate controls the gene expression and development of DCs through epigenetic regulation and DC-related transcription factors.

immunology↗

bioRxiv2025

Gelsolin Counteracts ER Stress-Driven Inflammatory Circuits in Psoriasis-like Dermatitis

Psoriasis is a chronic inflammatory skin disorder driven by amplified communication between immune cells and keratinocytes. Here, we show that imiquimod (IMQ) triggers organelle stress responses that directly contribute to this pathogenic circuit. In dendritic cells (DCs), IMQ promotes formation of ER-mitochondria contact sites (MAMs), inducing ER stress and activation of the unfolded protein response (UPR). These pathways act independently of, yet converge with, TLR7/MyD88 signaling to enhance IL-23 expression. IMQ also increases cytosolic Ca{superscript 2}+, facilitating NLRP3 inflammasome activation and release of mitochondrial DNA (mtDNA). In parallel, keratinocytes exposed to IMQ activate UPR-dependent genes, including Defb14 (mBD14), a psoriasis-associated antimicrobial peptide. Extracellular mtDNA and mBD14 then cooperatively stimulate plasmacytoid DCs through TLR9, establishing a feed-forward inflammatory loop. We further identify Gelsolin as a direct IMQ-binding protein that mitigates IMQ-induced ER stress; its loss amplifies ER stress, UPR activation, and oxidative stress, and its expression is reduced in human psoriatic lesions. Thus, MAM-UPR signaling links intracellular organelle stress to the intercellular networks that drive psoriatic inflammation, with Gelsolin acting as a critical intrinsic safeguard.

immunology↗

bioRxiv2025

Synchronous and asynchronous counterillumination by three types of photophores in the firefly squid, Watasenia scintillans

Countershading--animal body coloration that is darker on the dorsum than the ventrum--is a form of crypsis achieved through a gradient in skin pigmentation. Counterillumination is somewhat similar, achieving crypsis in midwater marine organisms by emitting downward-directed bioluminescence. Although mesopelagic squids are assumed to use counterillumination, high-resolution spatiotemporal changes in illumination, particularly for each photophore type, have not been elucidated. Watasenia scintillans has three types of photophores on its ventral surfaces: blue- and green-emitting ventral photophores and ocular photophores. It is demonstrated here that all three types of photophores are synchronously, reversibly, and repeatedly involved in counterillumination in response to changes in dim overhead lighting. Furthermore, the green-emitting photophores maintained luminescence in darkness, and their on/off switching is precisely regulated within the ambient temperature range. The photoreceptors responsible for counterillumination are extraocular photosensitive vesicles (EOPs) rather than eyes. Exposure of EOPs to visible light (blue, green, and yellow) elicited counterillumination in proportion to light intensity. No color shifts (such as from green to blue) were observed in any of the photophores. While synchronous illumination seems to support the crypsis hypothesis, the ability to independently control each photophore type could also support a previous hypothesis of conspecific signaling. Significance StatementBioluminescence is widespread among deep-sea organisms, yet the specific functions of individual light-producing organs distributed across the body surface remain underexplored. In this study, three types of ventral photophores in the firefly squid, Watasenia scintillans, were video-recorded, revealing their synchronous involvement in counterillumination--a mechanism that obscures the body silhouette when viewed from below against blue downwelling surface light. Notably, green-emitting photophores remained illuminated for extended periods in darkness, indicating a potential role in visual communication among conspecifics. The video-based techniques employed to quantify individual photophore activity provide new opportunities to investigate photo-signaling in animals inhabiting the mesopelagic zone.

animal behavior and cognition↗

bioRxiv2025

Arabidopsis aneuploidy mutant C30-81-as6, possesses enormous variations in multiple phenotypic characteristics.

Heavy-ion beam irradiation can be recognized as one of the powerful mutagenesis techniques because it induces high mutation frequency, minimal damage to the other traits and the possibility of having large DNA fragmental mutations. Aneuploid cells may have an additional or fewer number of chromosomes compared to their wild-type. The mutant line of C30-81-as6 is an ion beam-generated, Arabidopsis Col-0 based, aneuploid mutant line confirmed by whole genome sequence analysis, DNA quantity measurement using flow cytometry analysis and microscopic observations of additional chromosome. The mutant shows abnormal leaf shapes, petioleless rosette leaves, elevated trichome bases and later flowering phenotypes. Segregation analysis confirmed that additional DNA amount is correlated with observed phenotype since mutants showing intermediate phenotype possess moderate DNA quantities. A set of candidate causal genes was identified using up and downregulated differentially expressed genes in transcriptome analysis. Gene ontology analysis further supports mutant phenotypic characteristics and provides insights into its functional priorities, including promotion of cellular structure and energy production. Meanwhile, the downregulation of senescence-related gene ontology terms validates its extended vegetative phase. The whole genome sequence analysis based chromosome rearrangement prediction and the gene density mapping of upregulated DEGs, suggested that the long arm of chromosome 2 is a main component of the additional chromosome. In addition, the phenotype of C30-81-as6 largely resembles Arabidopsis additional chromosome 2 containing aneuploidy mutant. The ion beam mutagenesis generated aneuploidy mutant that may possess a fused DNA fragmented chromosome and it may successfully challenge the wild-type plants for establishment in nature.

genetics↗

bioRxiv2025

DISC1-PML protein interaction for congenital CMV infection-induced cortical neural progenitor deficit: perturbance of host signaling via viral IE1

Congenital CMV infection is the most common perinatal infection, affecting up to 0.5% of infants. This elicits long-term disabilities that include neuropsychiatric manifestations, such as intellectual disability, microcephaly. Despite its high prevalence, the underlying mechanism of how congenitally acquired CMV infection causes brain pathology remains unknown. Here we discovered the molecular interplay of key host (DISC1 and PML) and viral (IE1) proteins within the neural progenitor cells, which underlay an attenuated neural progenitor proliferation. Abolishing the viral IE1 protein by delivering IE1-targeting CRISPR/Cas9 to fetal brain rescued this progenitor cell deficit, a key pathology in congenital CMV infection. A selective targeting to a viral-specific protein by the CRISPR/Cas9 system is minimal in off-target effects. Therefore, we believe that a pivotal role of IE1 in an attenuated neural progenitor proliferation in the developing cortex through its interfering with interaction between host DISC1 and PML proteins.

developmental biology↗

bioRxiv2025

Independent component analysis disentangles fluorescence signals from diffusing single molecules

Multiparameter measurements offer new possibilities of single-molecule fluorescence experiments for detecting and quantifying heterogeneity in freely diffusing molecules. However, data analysis remains challenging due to limited photon rates from individual molecules. Here, we present independent fluorescence component analysis (IFCA), a universal analytical framework that applies independent component analysis (ICA) to unmix multiparameter fluorescence signals. In this work, we developed an efficient algorithm of ICA for multiparameter photon data based on third-order cumulant tensor decomposition. To validate its performance, we applied IFCA to a static mixture of fluorescent dyes and found that IFCA enables robust separation of signals from five species in a nanomolar mixture solution with a 5 {micro}s binning time. We further analyzed a photon dataset from a FRET-labeled DNA construct using IFCA, demonstrating its capability to quantitatively characterize signals from subpopulations exchanging on a sub-millisecond time scale in a model-independent manner. These findings highlight the high ability of IFCA for quantitative analysis of complex molecular systems exploiting these advantages.

biophysics↗

bioRxiv2025

The role of GATA2 in the expression of the soluble decoy receptor ST2/IL1RL1 in human and mouse mast cells

The ST2/IL1RL1 gene encodes a receptor subunit for IL-33. The ST2/IL1RL1 gene is transcribed and translated to two splice variants, full-length ST2 (ST2L) and soluble ST2 (sST2). ST2L is expressed on cell surface as membrane bound molecule and forms a heterodimer with IL-1RAcP, which plays an important role in Th2 transduces a signaling of IL-33. In contrast, sST2 blocks the IL-33-signaling via functioning as a decoy receptor of IL-33. In this study, we analyzed the regulatory mechanisms of the gene expression of sST2 in mast cell, the major source of sST2. We found that a hematopoietic cell-specific transcription factor GATA2 is essential for sST2 expression in human mast cells (a cell line and primary cells) and mouse mast cells. Various assays including ChIP assay, reporter assay, and 3C assay revealed that GATA2 binding to the distal promoter of the IL1RL1 gene transcriptionally activates proximal promoter-driven expression of sST2 through chromosomal conformation.

immunology↗

bioRxiv2025

PU.1 and TGF-β signaling transactivate CD103 expression in mast cells and dendritic cells: Opposite roles of GATA2 in the expression of mucosal mast cell-specific genes

Mucosal mast cells (MMCs) are distinguished from connective tissue MCs by the specific expression of integrin CD103 (E/{beta}7) and MC proteases Mcpt1 and Mcpt2. Although the expression of the Mcpt1 and Mcpt2 genes is cooperatively regulated by the transcription factor GATA2 and TGF-{beta} signaling in MMCs, the transcriptional mechanism of CD103 expression remains unknown. Here, we found that surface CD103 and Itgae mRNA levels were significantly increased by the knockdown (KD) of Gata2 in bone marrow-derived MCs (BMMCs), which was accelerated by a TGF-{beta} stimulation. Since the mRNA levels of Spi1 (encoding PU.1) were increased in Gata2 KD BMMCs, we examined the effects of PU.1 on CD103 expression. As expected, CD103 levels on BMMCs were significantly decreased by Spi1 KD and increased by Spi1 overexpression. Spi1 KD suppressed Itgae expression even in the presence of TGF-{beta} in BMMCs and peritoneal MCs, whereas Gata2 KD amplified the TGF-{beta}-induced increase in Itgae expression. The amount of PU.1 binding to the cis-element in the Itgae gene was significantly and moderately increased by Gata2 KD and the TGF-{beta} stimulation, respectively. Since PU.1 is an essential transcription factor for dendritic cells (DCs), we examined the role of PU.1 in CD103 expression on DCs. The KD experiment using BMDCs showed a significant decrease in CD103 levels in Spi1 siRNA-transfected BMDCs. We concluded that PU.1 affected CD103 expression on MMCs and DCs by transactivating the Itgae gene, and also that GATA2, which positively regulated the MMC-specific expression of Mcpt1 and 2, inhibited CD103 expression by repressing PU.1.

molecular biology↗

bioRxiv2025

Neuropeptidergic circuit modulation of developmental sleep in Drosophila

Sleep-wakefulness regulation dynamically evolves along development in a wide range of organisms. While the mechanism regulating sleep in adults are relatively well understood, little is known about its counterpart in early developmental stages. Here we report a neuropeptidergic circuitry that modulates sleep in developing Drosophila larvae. Through an unbiased screen, we identified the neuropeptide Hugin and its receptor PK2-R1 as critical regulators of larval sleep. Our genetic and behavioral data suggest that HugPC neurons secrete Hugin peptides to activate Insulin-producing cells (IPCs), which expresses a Hugin receptor PK2-R1. IPCs, in turn, release insulin-like peptides (Dilps) to regulate sleep. We further show that the Hugin/PK2-R1 axis is dispensable for adult sleep. Our findings thus reveal the neuromodulatry circuit that regulates developmental sleep in larvae, and highlight differential impacts of the same modulatory axis on early-life sleep and adult sleep.

neuroscience↗

bioRxiv2024

A novel RyR2-selective stabilizer prevents and ameliorates severe arrhythmias in stress-induced ventricular tachycardia

Background and PurposeAberrant activation of the type 2 ryanodine receptor (RyR2) causes lethal arrhythmias, such as catecholaminergic polymorphic ventricular tachycardia (CPVT). Developing drugs that suppress RyR2 hyperactivation may be key to novel arrhythmia treatments. This study evaluated the antiarrhythmic potential of Ryanozole, a recently developed novel RyR2 modulator with high affinity and selectivity, using CPVT mouse models harboring mutant RyR2s. Experimental approachIn vitro effects of Ryanozole were evaluated by ER Ca2+-based assay and [3H]Ryanodine binding assay using RyR2-expressing HEK293 cells. Two lines of mice with different arrhythmia severity, RyR2-R420W and -K4750Q, were employed for in vivo assessments. Intracellular Ca2+ signals were analyzed in isolated cardiomyocytes using Cal520. Antiarrhythmic effects were evaluated by ECG under catecholaminergic challenge in anesthetized mice and during spontaneous arrhythmias in conscious mice. ECG and echocardiographic parameters were evaluated before and after drug administration. Key resultsRyanozole inhibited both wild type and mutant RyR2s with similar IC50 of 15-40 nM. The inhibition was more potent at lower cytosolic Ca2+ concentrations. It suppressed Ca2+ waves and Ca2+ sparks without affecting action potential-evoked Ca2+ transients. Ryanozole effectively prevented adrenaline-induced arrhythmias and rapidly terminated spontaneous arrhythmias during daily activity. Importantly, Ryanozole did not impair cardiac conduction or contractility, unlike conventional antiarrhythmic drugs. Conclusions and implicationsRyanozole strongly suppresses RyR2 under diastolic Ca2+ conditions, thereby preventing the arrhythmogenic trigger of aberrant Ca2+ release. This mechanism likely provides potent antiarrhythmic effects while preserving cardiac function. Ryanozole is a promising therapeutic candidate treating RyR2-mediated arrhythmias, such as CPVT.

pharmacology and toxicology↗

bioRxiv2024

Effect of heterozygous deletions on phenotypic changes and dosage compensation in Arabidopsis thaliana

Heterozygous deletions, which include a large number of genes, are often caused by the induction of mutations. The induction of gene dosage compensation should be considered when assessing the effects of heterozygous deletions on phenotypic changes. This mechanism is known to balance the expression levels of genes with different copy numbers in sex chromosomes, but it is also known to operate in autosomes. In the present study, 12 Arabidopsis thaliana BC1 mutants with heterozygous deletions were produced by crossing wild-type Col-0 plants with mutants induced by heavy ion beams. The sizes of the deletions ranged from 50.9 kb to 2.03 Mb, and the number of deleted genes ranged from 8 to 92. Nine of the 12 BC1 mutants showed phenotypic changes in fresh weight 14 days after cultivation or during the flowering period. RNA-sequencing (RNA-seq) analyses of 14-day-old leaves, 40-day-old leaves, and flower buds showed that dosage compensation did not occur in any stage or tissue tested. These results indicate that heterozygous deletions cause phenotypic changes owing to the absence of dosage compensation. Article SummaryIn this study, we examined the impact of heterozygous deletions in Arabidopsis thaliana. By crossing wild-type Col-0 plants with mutants induced by heavy ion beams, we created 12 BC1 mutants, each having heterozygous deletions. The deletions ranged from 50.9 kb to 2.03 Mb, affecting 8 to 92 genes. Nine mutants showed changes in fresh weight or flowering time. RNA-seq analyses of leaves and flower buds revealed no gene dosage compensation. Our findings indicate that phenotypic changes result from the lack of dosage compensation in heterozygous deletions.

genetics↗

bioRxiv2024

Flow zoometry of Drosophila

Drosophila serves as a highly valuable model organism across numerous fields including genetics, immunology, neuroscience, cancer biology, and developmental biology. Central to Drosophila-based biological research is the ability to perform comprehensive genetic or chemical screens. However, this research is often limited by its dependence on laborious manual handling and analysis, making it prone to human error and difficult to discern statistically significant or rare events amid the noise of individual variations resulting from genetic and environmental factors. In this article we present flow zoometry, a whole-animal equivalent of flow cytometry for large-scale, individual-level, high-content screening of Drosophila. Our flow zoometer automatically clears the tissues of Drosophila melanogaster, captures three-dimensional (3D) multi-color fluorescence tomograms of single flies with single-cell volumetric resolution at an unprecedented throughput of over 1,000 animals within 48 hours (24 hr for clearing; 24 hr for imaging), and performs AI-enhanced data-driven analysis - a task that would traditionally take months or years with manual techniques. To demonstrate its broad applications, we employed the flow zoometer in various laborious screening assays, including those in toxicology, genotyping, and tumor screening. Flow zoometry represents a pivotal evolution in high-throughput screening technology: previously from molecules to cells, now from cells to whole animals. This advancement serves as a foundational platform for "statistical spatial biology", to improve empirical precision and enable serendipitous discoveries across various fields of biology.

bioengineering↗

bioRxiv2024

Client recognition differences between PDI and ERp46 to guide oxidative folding

Endoplasmic reticulum (ER)-resident protein disulfide isomerase (PDI) family members function not only as disulfide bond-catalysts but also as chaperones for the oxidative folding of client proteins. However, due to the scarcity of structural data, the client recognition mechanism remains poorly understood. We report the distinct recognition mechanisms for PDI/ERp46 proteins to recruit a reduced and denatured bovine pancreatic trypsin inhibitor (BPTI). NMR data demonstrated that PDI recognizes a broad region consisting of [~]30 amino acid residues in unfolded BPTI in order to function as a chaperone, while ERp46 interacts nonspecifically and weakly with unfolded BPTI to promiscuously and rapidly introduce disulfide bonds. These two distinct client recognition modes are likely important for the functional modulation of the disulfide-catalyst and chaperone against client proteins. Client recognition differences between PDI family proteins likely contribute to determining whether disulfide bonds are introduced into the client protein or aggregates are reduced to an unfolded state during the early folding step. Thus, the mammalian ER ensures concerted protein quality control through the differences in the client recognition modes of PDI family proteins, resulting in the production of large quantities of multiple-disulfide bonded proteins.

biochemistry↗

bioRxiv2024

Roles of C/EBPα, GATA2, TGF-β-signaling, and epigenetic regulation in the expression of basophil-specific protease genes

In the present study, we analyzed the transcriptional regulation of genes encoding basophil-specific proteases Mcpt8 and Mcpt11 to clarify the molecular mechanisms by which the commitment between basophil and mast cell (MC) is determined. We used bone marrow-derived (BM) cells maintained in the presence of IL-3, in which basophil-like cells and MC-like cells exist. Knock down (KD) and overexpression of a transcription factor C/EBP showed that Cebpa mRNA levels were associated with those of Mcpt8 and Prss34 (a gene symbol of Mcpt11). Treatment with trichostatin A (TSA), a histone deacetylase inhibitor, decreased mRNA levels of Cebpa, Mcpt8, and Prss34 in BM cells, whereas these mRNA levels were increased by the treatment with an inhibitor of DNA methyltransferase. TSA treatment upregulated mRNA levels of Gata1 and Mitf in BM cells, and Mitf KD but not Gata1 KD increased mRNA levels of Cebpa and Prss34. Furthermore, Gata2 KD significantly decreased mRNA levels of Mcpt8 and Prss34 without affecting Cebpa mRNA level. In addition, mRNA levels of Gata1 and Mitf were increased in BM cells transfected with Cebpa siRNA, and decreased in Cebpa-overexpressing BM cells. We also found the TGF-{beta} treatment increased mRNA levels of Mcpt8, Prss34, along with upregulation of Gata2 and Cebpa transcription. Taken together, we conclude that the transcription of basophil-specific protease genes was positively regulated by C/EBP, GATA2, and TGF-{beta} signaling with modification of epigenetic regulation.

immunology↗

bioRxiv2024

Opioid-driven disruption of the septal complex reveals a role for neurotensin- expressing neurons in withdrawal

Because opioid withdrawal is an intensely aversive experience, persons with opioid use disorder (OUD) often relapse to avoid it. The lateral septum (LS) is a forebrain structure that is important in aversion processing, and previous studies have linked the lateral septum (LS) to substance use disorders. It is unclear, however, which precise LS cell types might contribute to the maladaptive state of withdrawal. To address this, we used single-nucleus RNA-sequencing to interrogate cell type specific gene expression changes induced by chronic morphine and withdrawal. We discovered that morphine globally disrupted the transcriptional profile of LS cell types, but Neurotensin-expressing neurons (Nts; LS-Nts neurons) were selectively activated by naloxone. Using two-photon calcium imaging and ex vivo electrophysiology, we next demonstrate that LS-Nts neurons receive enhanced glutamatergic drive in morphine-dependent mice and remain hyperactivated during opioid withdrawal. Finally, we showed that activating and silencing LS-Nts neurons during opioid withdrawal regulates pain coping behaviors and sociability. Together, these results suggest that LS-Nts neurons are a key neural substrate involved in opioid withdrawal and establish the LS as a crucial regulator of adaptive behaviors, specifically pertaining to OUD.

neuroscience↗

bioRxiv2023

Apolipoprotein-E transforms intracellular Amyloid-β oligomers to a more toxic state

It is poorly understood why ApoE variants are major genetic risk factors in Alzheimers disease (AD), which is associated with the aggregation of amyloid beta (A{beta}). Here we directly image specific changes in small A{beta} oligomers in rat brain cells that correlate with the cellular ApoE content. An inhibitor of A{beta}-ApoE interaction suppresses this change and concomitantly reduces A{beta} toxicity in a dose-dependent manner. Single-molecule techniques show changes both in the conformation and the stoichiometry of the oligomers. hiPSC-derived neural stem cells from Alzheimers patients also show similar changes. Interaction with ApoE therefore changes the oligomeric state, membrane affinity, and toxicity of A{beta} oligomers, and can be directly read out in live cells. Our findings suggest a rapid and quantitative assay for AD drug discovery. One-sentence summaryApoE causes specific toxicogenic modifications of A{beta} oligomers, and these changes can be directly imaged in live cells.

biochemistry↗