Biology subjects

Hayashi, Y.

Publications and source records attributed to Hayashi, Y..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

Beyond Basic Characterization and Omics: Immunomodulatory Roles of Platelet-Derived Extracellular Vesicles Unveiled by Functional Testing

Renowned for their role in hemostasis and thrombosis, platelets are also increasingly recognized for their contribution in innate immunity, immunothrombosis and inflammatory diseases. Platelets express a wide range of receptors, which allows them to reach a variety of activation endpoints and grants them immunomodulatory functions. Activated platelets release extracellular vesicles (PEVs), whose formation and molecular cargo has been shown to depend on receptor-mediated activation and environmental cues. This study compares the immunomodulatory profiles of PEVs generated via activation of platelets by different receptors, glycoprotein VI, C-type lectin-like receptor 2, and combining all thrombin-collagen receptors. Functional assays in vivo in zebrafish and in vitro in human macrophages respectively highlighted distinct homing and secretory responses triggered by the PEVs. In contrast, omics analyses of protein and miRNA cargo combined with physicochemical particle characterization found only subtle differences between the PEV types, which were insufficient to explain their different functional immunomodulatory profiles. Constitutively released PEVs, formed in the absence of an exogenous activator, displayed a disparate activation profile from the receptor induced PEVs. Our findings underscore that PEVs are tunable through receptor-mediated activation. To truly comprehend their role(s) in mediating platelet functions among immune cells, conducting functional assays is imperative. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/570750v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@75a9dborg.highwire.dtl.DTLVardef@e2787corg.highwire.dtl.DTLVardef@543525org.highwire.dtl.DTLVardef@6d1362_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2023

A liquid-like coat mediates chromosome clustering during mitotic exit

SummaryThe individualization of chromosomes during early mitosis and their clustering upon exit from cell division are two key transitions that ensure efficient segregation of eukaryotic chromosomes. Both processes are regulated by the surfactant-like protein Ki-67, but how Ki-67 achieves these diametric functions has remained unknown. Here, we report that Ki-67 radically switches from a chromosome repellent to a chromosome attractant during anaphase. We show that Ki-67 dephosphorylation during mitotic exit and the simultaneous exposure of a conserved basic patch induce the RNA-dependent formation of a liquid-like condensed phase on the chromosome surface. Experiments and coarse-grained simulations support a model in which the coalescence of chromosome surfaces driven by phase separation promote clustering of chromosomes. Our study reveals how the switch of Ki-67 from a surfactant to a liquid-like condensed phase can generate the mechanical forces during genome segregation that are required for re-establishing nuclear-cytoplasmic compartmentalization after mitosis.

cell biology↗

bioRxiv2023

Integration of shoot-derived polypeptide signals by root TGA transcription factors is essential for survival under fluctuating nitrogen environments

Unlike plants in the field, which experience significant temporal fluctuations in environmental conditions, plants in the laboratory are typically grown in controlled, stable environments. Therefore, signaling pathways evolved for survival in continuously fluctuating environments often remain functionally latent in laboratory settings. Here, we show that TGA1 and TGA4 act as hub transcription factors through which the expression of genes involved in high-affinity nitrate uptake are regulated in response to shoot-derived phloem mobile polypeptides, CEP DOWNSTREAM 1 (CEPD1), CEPD2 and CEPD-like 2 (CEPDL2) as nitrogen (N) deficiency signals, and Glutaredoxin S1 (GrxS1) to GrxS8 as N sufficiency signals. CEPD1/2/CEPDL2 and GrxS1-S8 competitively bind to TGA1/4 in roots, with the former acting as transcription coactivators that enhance the uptake of nitrate, while the latter function as corepressor complexes together with TOPLESS to limit nitrate uptake. Arabidopsis plants deficient in TGA1/4 maintain basal nitrate uptake and exhibit growth similar to wild-type plants in a stable N environment, but were impaired in regulation of nitrate acquisition in response to shoot N demand, leading to defective growth under continuously fluctuating N environments where rhizosphere nitrate ions switch periodically between deficient and sufficient states. TGA1/4 are crucial transcription factors that enable plants to survive under fluctuating and challenging N environmental conditions.

plant biology↗

bioRxiv2023

Complete suspension culture of human induced pluripotent stem cells supplemented with suppressors of spontaneous differentiation

Human induced pluripotent stem cells (hiPSCs) are promising resources for producing various types of tissues in regenerative medicine; however, the improvement in a scalable culture system that can precisely control the cellular status of hiPSCs is needed. Utilizing suspension culture without microcarriers or special materials allows for massive production, automation, cost-effectiveness, and safety assurance in industrialized regenerative medicine. Here, we found that hiPSCs cultured in suspension conditions with continuous agitation without any microcarriers or extracellular matrix components were more prone to spontaneous differentiation than those cultured in conventional adherent conditions. Adding PKC{beta} and Wnt signaling pathway inhibitors in the suspension conditions suppressed the spontaneous differentiation of hiPSCs into ectoderm and mesendoderm, respectively. In these conditions, we successfully completed the culture processes of hiPSCs including the generation of hiPSCs from peripheral blood mononuclear cells with the expansion of bulk population and single-cell sorted clones, long-term culture with robust self-renewal characteristics, single-cell cloning, direct cryopreservation from suspension culture and their successful recovery, and efficient mass production of a clinical-grade hiPSC line. Our results demonstrate that precise control of the cellular status in suspension culture conditions paves the way for their stable and automated clinical application.

bioengineering↗

bioRxiv2023

Large-scale annotated dataset for cochlear hair cell detection and classification

Our sense of hearing is mediated by cochlear hair cells, localized within the sensory epithelium called the organ of Corti. There are two types of hair cells in the cochlea, which are organized in one row of inner hair cells and three rows of outer hair cells. Each cochlea contains a few thousands of hair cells, and their survival is essential for our perception of sound because they are terminally differentiated and do not regenerate after insult. It is often desirable in hearing research to quantify the number of hair cells within cochlear samples, in both pathological conditions, and in response to treatment. However, the sheer number of cells along the cochlea makes manual quantification impractical. Machine learning can be used to overcome this challenge by automating the quantification process but requires a vast and diverse dataset for effective training. In this study, we present a large collection of annotated cochlear hair-cell datasets, labeled with commonly used hair-cell markers and imaged using various fluorescence microscopy techniques. The collection includes samples from mouse, human, pig and guinea pig cochlear tissue, from normal conditions and following in-vivo and in-vitro ototoxic drug application. The dataset includes over 90,000 hair cells, all of which have been manually identified and annotated as one of two cell types: inner hair cells and outer hair cells. This dataset is the result of a collaborative effort from multiple laboratories and has been carefully curated to represent a variety of imaging techniques. With suggested usage parameters and a well-described annotation procedure, this collection can facilitate the development of generalizable cochlear hair cell detection models or serve as a starting point for fine-tuning models for other analysis tasks. By providing this dataset, we aim to supply other groups within the hearing research community with the opportunity to develop their own tools with which to analyze cochlear imaging data more fully, accurately, and with greater ease.

neuroscience↗

bioRxiv2023

Collective Almost Synchronization Modeling Used for Motor Imagery EEG Classification

Classification based on feature extraction is a crucial technique to develop Brain Computer Interface (BCI) systems. The human brain can be considered as a dynamical system, and its behavior measured by EEG signals can be modeled by a group of nonlinear oscillators. Exploring the dynamical nature of EEG signals along with model based approach may improve classification accuracy in BCI. This study proposes a novel feature extraction method for the classification of Motor Imagery (MI) EEG using a dynamical network model operating in a special collective state, so called Collective Almost Synchronization (CAS). The CAS, the nonlinear oscillators set to operate in a weakly coupled regime, can be used to model an EEG. Purpose of this study is to investigate the performance of the CAS model to identify features for the classification of MI states. To achieve this goal, a linear regression method is used and linear coefficients are extracted as feature vectors. Our approach boils down to identifying patterns in the MI-EEG by associating them to the coefficients of a linear regression (or weights of an output function) constructed to model the MI-EEG signals from simulated time-series generated by a dynamical neural network. The dataset 2b from BCI Competition-IV was used to evaluate the performance of the proposed method. Results indicate that the CAS-based classification method is more robust in extracting distinguishable features from EEG signals as compared with other state-of-the-art methods. The proposed method achieved better performance on two-class MI classification. Moreover, the method developed in this study for MI classification across subjects is effective with 74.03% of the accuracy.

neuroscience↗

bioRxiv2023

DRACC1, a major postsynaptic protein, regulates the condensation of postsynaptic proteins via liquid-liquid phase separation

Numerous proteome analyses have been conducted on the postsynaptic density (PSD), a protein condensate beneath the postsynaptic membrane of excitatory synapses. Each has identified several hundred to thousands of proteins. While proteins with predictable functions have been well studied, functionally uncharacterized proteins are mostly overlooked. In this study, we perform a meta-analysis of the 35 PSD proteome datasets, including 5,869 proteins, identifying 97 uncharacterized proteins that appeared in multiple datasets. We focus on the top-ranked protein, FAM81A, renamed DRACC1. DRACC1 is expressed in forebrain neurons and enriched at the synapse. DRACC1 interacts with PSD proteins, including PSD-95, SynGAP, and NMDA receptors, and promotes liquid-liquid phase separation of those proteins. Consistently, the downregulation of DRACC1 in neurons causes a decrease in the size of PSD-95 puncta and the frequency of neuronal firing. Our results characterize DRACC1 as a novel synaptic protein facilitating the assembly of proteins within PSD. It also indicates the effectiveness of a meta-analytic approach of existing proteome datasets in identifying uncharacterized proteins.

neuroscience↗

bioRxiv2022

Genetically encoded multimeric tags for intracellular protein localisation in cryo-EM

Cryo-electron tomography is a powerful label-free tool for visualizing biomolecules in their native cellular context at molecular resolution. However, the precise localisation of biomolecules of interest in the tomographic volumes is challenging. Here, we present a tagging strategy for intracellular protein localisation based on genetically encoded multimeric particles (GEMs). We show the applicability of drug-controlled GEM labelling of endogenous proteins in cryo-electron tomography and cryo-correlative fluorescence imaging in human cells.

cell biology↗

bioRxiv2022

Image-based quantification of Arabidopsis thaliana stomatal aperture from leaf images

The quantification of stomatal pore size has long been a fundamental approach to understand the physiological response of plants in the context of environmental adaptation. Automation of such methodologies not only alleviates human labor and bias, but also realizes new experimental research methods through massive analysis. Here, we present an image analysis pipeline that automatically quantifies stomatal aperture of Arabidopsis thaliana leaves from brightfield microscopy images containing mesophyll tissue as noisy backgrounds. By combining a YOLOX-based stomatal detection submodule and a U-Net-based pore segmentation submodule, we achieved 0.875 mAP50 (mean average precision; stomata detection performance) and 0.745 IoU (intersection of union; pore segmentation performance) against images of leaf discs taken with a brightfield microscope. Moreover, we designed a portable imaging device that allows easy acquisition of stomatal images from detached/undetached intact leaves on-site. We further combined this device with fine-tuned models of the pipeline we generated here and recapitulated manual measurement of stomatal responses against pathogen inoculation. Utilization of our hardware and pipeline for automated stomatal aperture measurements is expected to accelerate research on stomatal biology of model dicots.

plant biology↗

bioRxiv2022

Structure and Function of Gli123 Involved in Mycoplasma mobile Gliding

Mycoplasma mobile is a fish pathogen that glides on solid surfaces by means of a unique mechanism. The gliding machinery of M. mobile is composed of internal and surface structures. In the present study, we focused on the function and structure of Gli123, a surface protein that is essential for the localization of other surface proteins. The amino acid sequence of Gli123, which is 1128 amino acids long, contains lipoprotein-specific repeats. We isolated the native Gli123 protein from M. mobile cells and a recombinant protein, rGli123, from Escherichia coli. The isolated rGli123 complemented a non-binding and non-gliding mutant of M. mobile that lacked Gli123. Circular dichroism and rotary-shadowing electron microscopy (EM) showed that rGli123 has a structure that is not significantly different from that of the native protein. Rotary-shadowing EM suggested that the molecules changed their shape between globular and rod-like structures, depending on the ionic strength of the solution. Negative-staining EM coupled with single-particle analysis revealed that Gli123 forms a globular structure featuring a small protrusion with dimensions of 20.0, 14.5, and 16.0 nm. Small-angle X-ray scattering analyses indicated a rod-like structure composed of several tandem globular domains with total dimensions of approximately 34 nm length and 4 nm width. Both molecular structures were suggested to be dimers based on the predicted molecular size and structure. Gli123 may have evolved by multiplication of repeating lipoprotein units and acquired clumping role of surface proteins. IMPORTANCEMycoplasmas are pathogenic bacteria that are widespread in animals. They are characterized by small cell and genome sizes but are equipped with unique abilities to escape host immunity, such as surface variation and gliding. Here, we focused on a surface-localizing protein that is essential for Mycoplasma mobile gliding. The findings of this study suggested that the protein undergoes drastic conformational changes between its rod-like and globular structures. These changes may be caused by a repetitive structure common in the surface proteins that is responsible for the modulation of the cell surface structure and related to the assembly process for the surface gliding machinery. An evolutionary process for this unique mycoplasma gliding mechanism has also been suggested in the present study.

microbiology↗

bioRxiv2022

Gene expression profiles of chemosensory genes of termite soldier and worker antennae

Termite caste differentiation and social behavior are appropriately regulated by the chemical signals among individuals in each colony. Signal transduction is well known to be triggered by the reception of odorant molecules by some binding proteins in the antennae, after which, a signal is transmitted to chemosensory receptors. However, there is insufficient information on the role of chemosensory genes involved in signal transduction in termites. Here, we identified the genes involved in chemosensory reception in the rhinotermitid termite Reticulitermes speratus, and performed a genome-wide comparative transcriptome analysis of worker and soldier antennae. First, we identified 31 odorant-binding proteins (OBPs), and three chemosensory protein A (CheA) from the available genome sequence data. Thereafter, we performed RNA sequencing to compare the expression levels of OBPs, CheAs, and previously identified chemosensory receptor genes between workers and soldiers antennae. Of note, there were no receptor genes with significant differences in expression between castes. However, the expression levels of three non-receptor genes (OBP, CheA, and Sensory neuron membrane protein) were significantly different between castes. Quantiative polymerase chain reaction (qPCR) analysis using antennae and other head parts confirmed that these genes were highly expressed in soldier antennae. Finally, independent qPCR analysis showed that the expression patterns of these genes were altered in soldiers from different social contexts. The present results suggest that some non-receptor protein genes are involved in the social behaviors of termites.

evolutionary biology↗

bioRxiv2022

HOTARU: Automatic sorting system for large scale calcium imaging data

Currently, calcium imaging allows long-term recording of large-scale neuronal activity in diverse states. However, it remains difficult to extract neuronal dynamics from recorded imaging data. In this study, we propose an improved constrained nonnegative matrix factorization (CNMF)-based algorithm and an effective method to extract cell shapes with fewer false positives and false negatives through image processing. We also show that the evaluation metrics obtained during image and signal processing can be combined and used for false-positive cell determination. For the CNMF algorithm, we combined cell-by-cell regularization and baseline shrinkage estimation, which greatly improved its stability and robustness. We applied these methods to real data and confirmed their effectiveness. Our method is simpler and faster, detects more cells with lower firing rates and signal-to-noise ratios, and enhances the quality of the extracted cell signals. These advances can improve the standard of downstream analysis and contribute to progress in neuroscience.

neuroscience↗

bioRxiv2022

Dynamic de novo adipose tissue development during metamorphosis in Drosophila melanogaster

Adipose tissue is a central organ for controlling systemic metabolism both in invertebrates and vertebrates. Here, we have investigated the cellular mechanisms of the adult-type fat body (AFB) development in Drosophila. We have established genetic tools that allow visualization and genetic manipulations of cells in the AFB lineage from early in metamorphosis. We identified precursor cells that give rise to the AFB and delineated dynamic cellular mechanisms underlying AFB formation. These precursor cells displayed polarized cell shapes and oriented motility, with emigration from the thorax and subsequent dispersal to the abdomen and head. After the migration period, these cells adhered to each other, assembling into the AFB with a sheet-like architecture. Continuous cell proliferation occurred during and after the large-scale migration to achieve appropriate fat tissue mass. Homotypic cell fusion after the sheet formation contributed to the establishment of multinucleated cells in the AFB. We also examined candidate gene functions, and our results argue that Rac1, ecdysone signaling, and the transcription factor Serpent support adult fat body organogenesis. Brief Summary StatementDrosophila adult fat body precursor cells form adult adipose tissue during metamorphosis by directional migration, continuous cell proliferation, and homotypic cell fusion.

developmental biology↗

bioRxiv2022

Thoracic crop formation is spatiotemporally coordinated with flight muscle histolysis during claustral colony foundation of a Lasius japonicus queen

In a majority of ants, a newly mated queen independently founds a colony and claustrally raises her first brood without foraging outside the nest. During claustral independent colony foundation (ICF) in several ants, the esophagus of the founding queen expands and develops into a thoracic crop, which is then filled with a liquid substrate for larval feeding. It has been suggested that these substrates are converted from her body reserves (e.g., histolyzed flight muscles) or redistributed from a gastral crop. Here, we examined thoracic crop development in Lasius japonicus during claustral ICF. The foundresses claustrally fed their larvae from week 2 to 5 after ICF onset, and the first worker emerged at week 6. The development proceeded as follows: in week 0, foundress dorsal esophagus wall was pleated and thickened. Then, from week 2 to 5, the esophagus expanded dorsally toward where flight muscles had been present, following flight muscle histolysis. Gastral crop expansion followed esophagus expansion. Thus, thoracic crop formation may be spatiotemporally coordinated with flight muscle histolysis in Lasius japonicus queens, and similar developmental regulations might be common in other claustral ICF ants.

zoology↗

bioRxiv2022

The Temporal and Contextual Stability of Activity Levels in Hippocampal CA1 Cells

Recent long-term optical imaging studies have demonstrated that the activity levels of hippocampal neurons in a familiar environment change on a daily to weekly basis. However, it is unclear whether there is any time-invariant property in the cells neural representations. In this study, using miniature fluorescence microscopy, we measured the neural activity of the mouse hippocampus in four different environments every 3 days. Although the activity level of hippocampal neurons fluctuated greatly in each environment across days, we found a significant correlation between the activity levels for different days, and the correlation was higher for averaged activity levels across multiple environments. When the number of environments used for averaging was increased, a higher activity correlation was observed. Furthermore, the number of environments in which a cell showed activity was preserved. Cells that showed place cell activity in many environments had greater spatial information content, and thus carried a higher amount of information about the current position. In contrast, cells that were active only in a small number of environments provided sparse representation for the environment. These results suggest that each cell has not only an inherent activity level but also play a characteristic role in the coding of space. Significance StatementRecent studies have revealed that place cell activity in the hippocampal CA1 cells exhibit instability on a daily to weekly scale. However, it is unclear whether there is any invariant property in the activity of the cells. In this study, we found that, although the activity level of CA1 neurons fluctuated greatly in one environment, the mean activity level across multiple environments was more stable. Furthermore, the number of environments in which a cell showed activity was preserved over time. These results suggest that even though the spatial code changes dynamically, each cell has an inherent activity level and plays a characteristic role in spatial coding.

neuroscience↗

bioRxiv2021

Hematopoietic stem and progenitor cells integrate Bacteroides-derived innate immune signals to promote gut tissue repair

Bone marrow (BM)-resident hematopoietic stem and progenitor cells (HSPCs) are often activated by bacterial insults to replenish the host hemato-immune system, but how they integrate the associated tissue damage signals to initiate distal tissue repair is largely unknown. Here, we showed that acute gut inflammation expands HSPCs in the BM through GM-CSFR activation, and directs them to inflamed mesenteric lymph nodes for further differentiation into myeloid cells specialized in gut tissue repair. We also identified that this process is exclusively mediated by Bacteroides, a commensal gram-negative bacteria, that activates innate immune signaling. In contrast, chronic gut inflammation reduces HSC potential for hematopoietic reconstitution and immune response against infection. Similarly, microbial signals contribute to aging-associated HSPC expansion. These findings establish a cross-organ communication that promotes tissue regeneration, but if sustained, impairs tissue homeostasis that may be relevant to aging and chronic disorders. SummaryThe infiltrating microbiota Bacteroides upon acute colitis directed MPP migration from the BM to the MLN for their subsequent expansion and differentiation into tissue-repairing Ly6C+/G+ cells, whereas chronic colitis impairs HSC functionality similarly as aging.

pathology↗

bioRxiv2021

Direct neuronal conversion of microglia/macrophages reinstates neurological function after stroke

Ischaemic brain injury causes permanent neuronal loss, which often results in persistent severe neurological dysfunctions. Although generating new neurons in the injured brain would be an ideal approach to replenish the lost neurons for repairing the damage, the adult mammalian brain retains only limited neurogenic capability. Here, we show that direct conversion of microglia/macrophages into neurons in the brain has great potential as a therapeutic strategy for ischaemic brain injury. After transient middle cerebral artery occlusion in adult mice, microglia/macrophages converge at the lesion core of the striatum, where neuronal loss is prominent. Targeted expression of a neurogenic transcription factor, NeuroD1, in microglia/macrophages in the injured striatum enables their conversion into induced neuronal cells that functionally integrate into the existing neuronal circuits. Furthermore, NeuroD1-mediated induced neuronal cell generation significantly improves neurological function in the mouse stroke model, and ablation of these cells abolishes the gained functional recovery. Our findings thus demonstrate that neuronal conversion contributes directly to functional recovery after stroke and shed further light on the development of therapies for ischaemic brain injury by in situ neuronal conversion technology.

neuroscience↗

bioRxiv2021

Aberrant accumulation of NIK promotes tumorigenicity by dysregulating post-translational modifications in breast cancer

Post-translational modifications and mRNA translation are frequently altered in human cancers. However, investigations to understand their roles in the cancer progression mechanism remain insufficient. In this research, we explored protein levels altered by translational or post-translational regulation by analyzing transcriptome and western blotting data of the highly malignant breast cancer cell lines. From these analyses, NIK was found to be upregulated at the protein level to predominantly activate the non-canonical NF-{kappa}B pathway in a breast cancer cell line. Furthermore, the increase in NIK protein production was attributed to the dysregulation of ubiquitin-proteasome system caused by a decrease in the translation of cIAP1. NIK upregulation contributed to tumorigenicity by regulating the expression of inflammatory response-related genes. Collectively, our study suggests that NIK is post-translationally modified and has the potential to be a therapeutic target and diagnostic marker for breast cancer.

cancer biology↗