Biology subjects

Takagi, S.

Publications and source records attributed to Takagi, S..

13 recordsLinked to original sources

bioRxiv2026

Effects of Arachis hypogaea extract on TRPV4 activation and epidermal barrier function

Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable non-selective cation channel and its activating stimuli include anandamide, bisandrographolide, citric acid, arachidonic acid metabolic products by epoxygenases, hypo-osmotic cell swelling, and warm temperature. TRPV4 is involved in Ca2+-dependent signal transduction in several tissues. Since the activation of TRPV4 facilitates adherens junction formation in the skin epithelium, compounds that activate TRPV4 are expected to maintain or improve the barrier function of epidermal cells. In this study, we found that the extract of Arachis hypogaea (A. hypogaea) activate human TRPV4 (hTRPV4). In the Ca2+-imaging experiment, the application of A. hypogaea extract exhibited an increase in intracellular Ca2+ concentration ([Ca2+]i) in HEK293T cells expressing hTRPV4. The [Ca2+]i increases by application of A. hypogaea extract were not observed in HEK293T cells expressing hTRPV1, mouse TRPV2, hTRPV3, hTRPM8, or hTRPA1. We then examined the physicochemical properties of the components responsible for TRPV4 activation. Ethanol extracts of A. hypogaea caused an increase in [Ca2+]i in hTRPV4-expressing HEK293JN cells, whereas water, chloroform, and hexane extracts showed no activity. Moreover, the application of A. hypogaea extract enhanced transepithelial electrical resistance in the keratinocyte monolayer. These results suggest that A. hypogaea extract may contribute to the maintenance and improvement of the epidermal barrier function.

pharmacology and toxicology↗

bioRxiv2025

A GPCR signaling pathway in insect odor detection

Odor detection differs fundamentally in vertebrates, which use G protein-coupled receptors (GPCRs)1,2, and insects, which employ ion channels3,4. Here, we report the first evidence for a GPCR defining tuning properties of insect olfactory sensory neurons. Single-cell transcriptomics of the Drosophila melanogaster antenna identified selective expression of the G{gamma}30A subunit in acid-sensing Ir64a-DC4 neurons5,6. G{gamma}30A is essential for broadening responses to long-chain acids, acting with Gs, G{beta}13F, adenylate cyclase Ac13E and the Cngl channel. We further discovered that Cirl, a latrophilin-family GPCR7, is broadly-transcribed in the antenna but the protein is localized only in Ir64a-DC4 sensory cilia, dependent upon G{gamma}30A, but not Ir64a. Importantly, loss of Cirl also narrows Ir64a-DC4 tuning properties. Homologous neurons in Drosophila sechellia naturally exhibit narrow acid tuning, despite functional conservation of Ir64a; these differences correlate instead with lower expression of metabotropic components. Our findings reveal unexpected roles for GPCR/metabotropic signaling in olfactory detection and divergence in insects.

neuroscience↗

bioRxiv2024

Olfactory projection neuron rewiring in the brain of an ecological specialist

Animals behaviours can vary greatly between even closely-related species. While changes in the sensory periphery have frequently been linked to species-specific behaviours, very little is known about if and how individual cell types in the central brain evolve. Here, we develop a set of advanced genetic tools to compare homologous neurons in Drosophila sechellia - which specialises on a single fruit - and Drosophila melanogaster. Through systematic morphological analysis of olfactory projection neurons (PNs), we reveal that global anatomy of these second-order neurons is conserved. However, high-resolution, quantitative comparisons identify a striking case of convergent rewiring of PNs in two distinct olfactory pathways critical for D. sechellias host location. Calcium imaging and labelling of pre-synaptic sites in these evolved PNs demonstrate that novel functional connections with third-order partners are formed in D. sechellia. This work demonstrates that peripheral sensory evolution is accompanied by highly-selective wiring changes in the central brain to facilitate ecological specialisation, and paves the way for systematic comparison of other cell types throughout the nervous system.

neuroscience↗

bioRxiv2024

Promoted extension of an epidermal cell by semaphorin in C. elegans revealed by a mosaic gene expression analysis by using the IR-LEGO single-cell gene induction system

One of the major functions of the semaphorin signaling system is the regulation of cell shape. In the nematode C. elegans, membrane-bound semaphorins SMP-1/2 (SMPs) regulate the morphology of epidermal cells via their receptor plexin, PLX-1. In the larval male tail of the SMPs/PLX-1 signaling mutants, the border between two epidermal cells, R1.p and R2.p, is displaced anteriorly, resulting in the anterior displacement of the anterior most ray, ray 1, in the adult male. To elucidate how the intercellular signaling mediated by SMPs regulates the position of the intercellular border, we performed mosaic gene expression analyses by using IR-LEGO (InfraRed Laser Evoked Gene Operator). We show that PLX-1 expressed in R1.p and SMP-1 expressed in R2.p is required for proper positioning of ray 1. The result suggests that SMPs signaling promotes extension, rather than retraction, of R1.p. This is in contrast to a previous finding that SMPs mediate inhibition of cell-extension of vulval precursor cells, another group of epidermal cells of C. elegans, indicating the context-dependence of cell shape control via the semaphorin signaling system.

cell biology↗

bioRxiv2023

Sensory neuron population expansion enhances odour tracking through relaxed projection neuron adaptation

The evolutionary expansion of sensory neuron populations detecting important environmental cues is widespread, but functionally enigmatic. We investigated this phenomenon through comparison of homologous neural pathways of Drosophila melanogaster and its close relative Drosophila sechellia, an extreme specialist for Morinda citrifolia noni fruit. D. sechellia has evolved species-specific expansions in select, noni-detecting olfactory sensory neuron (OSN) populations, through multigenic changes. Activation and inhibition of defined proportions of neurons demonstrate that OSN population increases contribute to stronger, more persistent, noni-odor tracking behavior. These sensory neuron expansions result in increased synaptic connections with their projection neuron (PN) partners, which are conserved in number between species. Surprisingly, having more OSNs does not lead to greater odor-evoked PN sensitivity or reliability. Rather, pathways with increased sensory pooling exhibit reduced PN adaptation, likely through weakened lateral inhibition. Our work reveals an unexpected functional impact of sensory neuron expansions to explain ecologically-relevant, species-specific behavior.

neuroscience↗

bioRxiv2023

Segment-specific axon guidance by Wnt/Fz signaling diversifies motor commands in Drosophila larvae

Functional diversification of homologous neuronal microcircuits is a widespread feature observed across brain regions as well as across species, while its molecular and developmental mechanisms remain largely unknown. We address this question in Drosophila larvae by focusing on segmentally homologous Wave command-like neurons, which diversify their wiring and function in a segment-specific manner. Anterior Wave (a-Wave) neurons extend axons anteriorly and connect to circuits inducing backward locomotion, whereas posterior Wave (p-Wave) neurons extend axons posteriorly and trigger forward locomotion. Here, we show that Frizzled receptors DFz2 and DFz4, together with the DWnt4 ligand, regulate the segment-specific Wave axon projection. DFz2 knock-down (KD) not only reroutes Wave axons to posterior neuromeres but also biases its motor command to induce forward instead of backward locomotion as tactile response. Thus, segment-specific axon guidance diversifies the function of homologous command neurons in behavioral regulation. Since control of anterior-posterior (A-P) axon guidance by Wnt/Fz-signaling is evolutionarily conserved, our results reveal a potentially universal molecular principle for formation and diversification of the command system in the nerve cord. Furthermore, this work indicates that sensorimotor transduction can be rerouted by manipulating a single gene in a single class of neurons, potentially facilitating the evolutionary flexibility in action selection. Impact statementRewiring the command neurons in the tactile circuit suffices to change the behavioral strategy of a whole animal, implying a "plug-and-play" flexibility in sensorimotor circuits.

neuroscience↗

bioRxiv2023

Latent inter-organ mechanism of idiopathic pulmonary fibrosis unveiled by a generative computational approach

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive disease characterized by complex lung pathogenesis affecting approximately three million people worldwide. While the molecular and cellular details of the IPF mechanism is emerging, our current understanding is centered around the lung itself. On the other hand, many human diseases are the products of complex multi-organ interactions. Hence, we postulate that a dysfunctional crosstalk of the lung with other organs plays a causative role in the onset, progression and/or complications of IPF. In this study, we employed a generative computational approach to identify such inter-organ mechanism of IPF. The approach works as follows: 1) To find unexpected relatedness of IPF to other diseases of non-lung organs and to identify molecular features that define such relatedness, 2) To identify differentially expressed genes between the lung tissues of IPF vs. those of non-IPF pulmonary disease patients, 3) To detect ligand-receptor relationships across multiple organs and their upstream and downstream signaling pathways in 1) and 2), 4) To generate a map of the inter-organ IPF mechanism with the molecular and cellular resolution. This approach found unexpected molecular relatedness of IPF to neoplasm, diabetes, Alzheimers disease, obesity, atherosclerosis, and arteriosclerosis. Furthermore, as a potential mechanism underlying this relatedness, we uncovered a putative molecular crosstalk system across the lung and the liver. In this inter-organ system, a secreted protein, kininogen 1, from hepatocytes in the liver interacts with its receptor, bradykinin receptor B1 in the lung. This ligand-receptor interaction across the liver and the lung leads to the activation of calmodulin pathways in the lung, leading to the activation of interleukin 6 and phosphoenolpyruvate carboxykinase 1 pathway across these organs. Furthermore, we retrospectively identified several pre-clinical and clinical evidence supporting this inter-organ mechanism of IPF. In conclusion, such feedforward and feedback system across the lung and the liver provides a unique opportunity for the development of the treatment and/or diagnosis of IPF. Furthermore, the result illustrates a generative computational framework for machine-mediated synthesis of mechanisms that facilitates and complements the traditional experimental approaches in biomedical sciences.

pathology↗

bioRxiv2023

Different Physical Parameters in the Bonds between Platelet Glycoprotein Ibalpha with von Willebrand factor and with Coagulant Factor XI -Results from the Molecular Dynamic Simulation-

BackgroundBoth von Willebrand factor (VWF) and coagulation factor XI (FXI) bind with platelet membrane glycoprotein (GP) Ib. However, the differences in the physical parameters in the bonds between VWF-GPIb and FXI-GPIb mediating different biological functions are unclear. MethodsThe FXI molecule was arranged in 9 different initial positions around the structure of GPIb bound to VWF. The position coordinate and velocity vectors of all atoms constructing VWF, GPIb, and FXI were calculated in each 2 femto (10-15) second using the Chemistry at HARvard Macromolecular Mechanics (CHARMM) force field. The physical parameters of VWF-GPIb and FXI-GPIb bonds were calculated by molecular dynamic (MD) simulations. ResultsMD calculation revealed 2.8 to 11.3 times greater positional fluctuations in atoms constructing FXI-GPIb as compared to those constructing VWF-GPIb (RMSDs: 5.9{+/-}1.5 to 18.1{+/-}7.9 [A] for FXI-GPIb vs 1.6{+/-}0.1 to 2.1{+/-}0.3 [A] for VWF-GPIb). The absolute value of non-covalent binding energy generated in FXI-GPIb (65.5{+/-}79.7 to 517.6{+/-}54.2 kcal/mol) was smaller than that generated in VWF-GPIb (678.5{+/-}58.3 to 1000.4{+/-}75.1 kcal/mol). The binding structure of VWF-GPIb was stable and was only minimally influenced by the presence of FXI-GPIb binding. ConclusionsOur MD calculation results revealed that atoms constructing the VWF-GPIb bond are physically more stable and produce more non-covalent binding energy than the bond of FXI-GPIb. The physical parameters in the VWF-GPIb bond were not largely influenced by FXI binding with GPIb.

bioengineering↗

bioRxiv2021

Acoustic frequency-dependent physical mechanism of sub-MHz ultrasound neurostimulation

Ultrasound is an innovative physical modality allowing non-invasive and reversible modulation of neural circuit activity in the brain with high spatial resolution. Despite growing interest in clinical applications, the safe and effective use of ultrasound neuromodulation has been limited by a lack of understanding of the physical mechanisms underlying its effects. Here, we demonstrate acoustic frequency-dependent physical effects that underlie ultrasound neuromodulation, where cavitation and radiation forces are the dominant sources of low- and high-frequency stimulation, respectively. We used 39.5 kHz and 500 kHz acoustic frequencies to stimulate cultured neural and glial cells, excised from rat cortex, to study acoustic frequency-dependent neural responses. We demonstrate increased evoked responses due to increased cavitation activity at the 39.5 kHz acoustic frequency. In contrast, notable cavitation activity was not detected at 500 kHz despite detection of evoked responses. Our work highlights the dependence of ultrasound neuromodulation on acoustic frequencies, with different physical effects underlying cell responses to low and high sub-MHz acoustic frequency ranges.

bioengineering↗

bioRxiv2021

Acoustic light-sheet microscopy

Light-sheet imaging of 3D objects with high spatial resolution remains an open challenge because of the trade-off between field-of-view (FOV) and axial resolution originating from the diffraction of light. We developed acoustic light-sheet microscopy (acoustic LSM), which actively manipulates the light propagation inside a large sample to obtain wide-field microscopic images deep inside a target. By accurately coupling a light-sheet illumination pulse into a planar acoustic pulse, the light-sheet can be continuously guided over large distances. We imaged a fluorescence-labeled transparent mouse brain for the FOVs of 19.3 x 12.4 mm2 and 9.7 x 5.9 mm2 with resolved microstructures and single cells deep inside the brain. Acoustic LSM creates new opportunities for the application of light-sheet in the field of industry to basic science. One Sentence SummaryAn acoustic-optical method overcomes a trade-off between field-of-view and axial resolution in light-sheet microscopy.

bioengineering↗

bioRxiv2021

A Novel Mouse Wound Model for Scar Tissue Formation in Abdominal-Muscle Wall

Scar tissue formation is a result of excess healing reactions after wounding. Hypertrophic scars scarcely develop in a mouse. In the present study, we established a novel experimental model of a scar-forming wound by resecting a small portion of the abdominal wall on the lower center of the abdomen, which exposed contractive forces by the surrounding muscle tissue. As a tension-less control, a back-skin excision model was used with a splint fixed onto the excised skin edge, and granulation tissue formed on the muscle facia supported by the back skeleton. One week after the resection, initial healing reactions such as fibroblast proliferation took place in both models. However, after 21 days, lesions with collagen-rich granulation tissues forming multiple nodular/spherical-like structures developed only in the abdominal-wall model. The lesions are analogous to scar lesions in humans. Such lesions, however, did not develop in the back-skin excision model. Therefore, this animal model is unique in that fibrous scar tissues form under a physiological condition without using any artificial factors and is valuable for studying the pathogenesis and preclinical treatment of scar lesions. Summary StatementScar lesions are hardly developed in animals. We thus developed a scar lesion in mice without using any artificial factors. The model is reliable, reproducible, and valuable.

pathology↗

bioRxiv2020

Culture influences audiovisual emotion perception in early sensory areas

Emotion perception from facial and vocal expressions is a multisensory process critical for human social interaction. When asked to judge emotions by attending to either face or voice, the accuracy was higher when facial expressions are congruent with vocal expressions than when they are incongruent. This congruency effect was shown to be affected by cultural background. Here we conducted functional MRI alongside a multisensory emotion perception task involving Japanese and Dutch participants. They were presented with movies in which congruent or incongruent emotions were expressed through faces and voices. The participants were asked to judge the emotion of either the face or the voice. Consistent with previous studies, behavioral results showed an interaction between group and task. fMRI results revealed that during voice-based judgement, congruency effects of the primary visual cortex, by means of the task related activity of congruent stimuli subtracted by that of incongruent stimuli, were more prominent in the Dutch group than in Japanese group. Finally, behavioral and neural congruency effects of the primary visual cortex were positively correlated only in the Dutch group. Taken together, our results show that culture affects the activities of early sensory areas in multisensory perception from facial and vocal expressions.

neuroscience↗

bioRxiv2018

Pharmacological inhibition of PRMT7 links arginine monomethylation to the cellular stress response

Protein arginine methyltransferases (PRMTs) regulate diverse biological processes and are increasingly being recognized for their potential as drug targets. Here we report the discovery of a potent, selective and cell active chemical probe for PRMT7. SGC3027 is a cell permeable prodrug, which in cells, is converted to SGC8158, a potent, SAM-competitive PRMT7 inhibitor. Inhibition or knockout of cellular PRMT7 resulted in drastically reduced levels of arginine monomethylation of HSP70 family members and other stress-associated proteins. Structural and biochemical analysis revealed that PRMT7-driven in vitro methylation of HSP70 at R469 requires an ATP-bound, open conformation of HSP70. In cells, SGC3027 inhibited methylation of both constitutive and inducible forms of HSP70, and led to decreased tolerance for perturbations of proteostasis including heat shock and proteasome inhibitors. These results demonstrate a role for PRMT7 and arginine methylation in stress response.

biochemistry↗