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Tsuchiya, Y.

Publications and source records attributed to Tsuchiya, Y..

17 recordsLinked to original sources

Latent-Space Residue-Pair Networks from Molecular Dynamics Distinguish Ligand-Activated and SAVI-Associated STING

Stimulator of interferon genes (STING) provides an informative model system for developing methods to extract and compare residue-pair fluctuation patterns from molecular dynamics (MD) trajectories. We combined a one-dimensional convolutional autoencoder trained on apo STING with temporal mean pooling, Mahalanobis-distance clustering, and residue-pair similarity networks to compare apo, ligand-bound, and SAVI-associated multi-mutant datasets using 25-dimensional latent descriptors. Networks constructed from clusters capturing state-dependent fluctuation patterns showed lid-dominated organization in the ligand-bound dataset and a1b1-enriched, structurally distributed relationships involving residue 281 in the multi-mutant dataset. These findings identify contrasting residue-pair fluctuation signatures in the analyzed trajectories and provide an interpretable framework for generating hypotheses about ligand-associated and mutation-associated dynamic allostery.

biophysics↗

The sex determination gene doublesex is essential for female-specific flight and hearing properties in Aedes aegypti mosquitoes

The acoustic communication system supporting reproduction in disease-transmitting mosquitoes is sexually dimorphic, from the sounds that mosquitoes make to the properties of their flagellar ears. The molecular mechanisms shaping these dimorphisms, however, remain unclear. Here, we explored the contributions of the female-specific isoform of the sex determination gene doublesex (dsxF) in specifying female-unique properties in the acoustic communication system of Aedes aegypti mosquitoes. CRISPR-Cas9 based generation of a novel dsxF knockout line found that dsxF mutant females were flightless due to lack of expression of a female-specific myosin gene, myo-fem, in the thorax. We found that DsxF directly binds to four different enhancer sites of myo-fem to promote gene expression. We observed that dsxF female ears exhibited intersex neuroanatomical characteristics and contained a more extensive auditory efferent network than control females. At the peripheral hearing function level, dsxF female ears displayed intersex tuning frequencies associated with increased expression of hearing genes in dsxF female ears compared to control females. We identified three hearing genes transcriptionally inhibited by DsxF via direct binding. DsxF is a bifunctional transcription factor, activating female-specific gene expression in thoraces whilst repressing male-biased gene expression in ears to coordinate female-unique features across sensory and motor systems.

neuroscience↗

Selective quality control of mistargeted mitochondrial proteins at the endoplasmic reticulum

In eukaryotic cells, the function of each organelle depends on its unique protein composition. Protein targeting errors threaten organelle identity and function, yet how mistargeting errors are detected and resolved remains poorly understood. Here, we show that mitochondrial import stress drives widespread rerouting of mitochondrial proteins to the endoplasmic reticulum (ER), with strong enrichment for hydrophobic oxidative phosphorylation (OXPHOS) components. Using proximity proteomics, a split-fluorescence reporter system, and genome-wide CRISPR screening, we find that mistargeted proteins partition into distinct classes with divergent fates, ranging from stable ER residence to rapid degradation by ER-associated degradation (ERAD). The clearance of these mislocalized proteins involves partially redundant ERAD branches, with the ubiquitin ligase MARCHF6 playing a central role. Together, these findings establish the ER as a key organelle for handling mistargeted mitochondrial proteins and reveal how ER quality control maintains proteostasis during mitochondrial dysfunction.

cell biology↗

Inducible degradation of endogenous proteins by AlissAID system and development of a photoactivatable inducer.

Protein analysis strategies involving targeted protein degradation are powerful approaches to determine gene functions. Auxin-inducible degron (AID) is among the most widely used methods for target protein knockdown. This system enables the rapid depletion of AID-tagged target proteins in an auxin-dependent manner. Various improved AID methods have been developed to date; however, the requirement to tag the target protein remains a common challenge. Here, we demonstrated the efficiency of the affinity-linker-based super-sensitive AID system for condition-knockdown of target proteins in cultured animal cells and mouse embryos. This system combines the improved AID method with small-molecule antibodies, enabling the control of GFP and mCherry fusion proteins. Additionally, this system can be used to degrade endogenous targets, such as Ras proteins. We also developed a novel inducer, caged 5-adamantyl-IAA, that precisely controlled targeted protein degradation under light irradiation. This advanced technique aids in the degradation of endogenous proteins of interest and can be used to develop new technologies for localized protein degradation.

cell biology↗

A long-distance inhibitory system regulates haustoria numbers in parasitic plants

The ability of parasitic plants to withdraw nutrients from their hosts depends on the formation of an infective structure known as the haustorium. How parasites regulate their haustoria numbers is poorly understood, and here, we uncovered that existing haustoria in the facultative parasitic plants Phtheirospermum japonicum and Parentucellia viscosa suppressed the formation of new haustoria on distant roots. Using Phtheirospermum japonicum, we found that this effect depended on the formation of mature haustoria and could be induced through the application of external nutrients. To understand the molecular basis of this root plasticity, we analyzed hormone response and found that existing infections upregulated cytokinin responsive genes first at the haustoria and then more distantly in Phtheirospermum shoots. We observed that infections increased endogenous cytokinin levels in Phtheirospermum roots and shoots, and this increase appeared relevant since local treatments with exogenous cytokinins blocked the formation of both locally and distantly formed haustoria. In addition, local overexpression of a cytokinin degrading enzyme in Phtheirospermum prevented this systemic inter-haustoria repression and increased haustoria numbers locally. We propose that a long-distance signal produced by haustoria negatively regulates future haustoria, and in Phtheirospermum, such a signaling system is mediated by a local increase in cytokinin to regulate haustoria numbers and balance nutrient acquisition.

plant biology↗

Hypoxia inhibits newt skeletal muscle dedifferentiation

Unlike mammals, newts are able to regenerate lost muscle tissue by dedifferentiating postmitotic muscle cells, which re-enter the cell cycle to form myogenic progenitors. This ability is considered central to the process of limb regeneration, yet the mechanisms underlying it remain poorly understood. Here, we leverage high-resolution time course bulk transcriptomics profiling to characterise molecular changes during differentiation and dedifferentiation of newt myotubes. We uncover that myogenesis is accompanied by a metabolic shift from glycolysis to OXPHOS, which is partially reverted upon dedifferentiation. By analysing early events during dedifferentiation, we identify TGF{beta} and members of the oxygen-responsive HIF family as putative plasticity inducers. We detect a stark, transient upregulation of HIF3A early during dedifferentiation, followed by a gradual downregulation of HIF2A. Finally, we show that hypoxia inhibits myotube cell cycle re-entry. These data provide a valuable resource to identify regulators of cellular plasticity and offer insights into the impact of oxygen signalling in regenerative processes.

developmental biology↗

Development of bright fluorescent auxin

Polar transport of the phytohormone auxin plays a crucial role in plant growth and response to environmental stimuli. Small-molecule tools that visualize auxin distribution in intact plants enable us to understand how plants dynamically regulate auxin transport to modulate growth. In this study, we developed a new fluorescent auxin probe, BODIPY-IAA2, which effectively visualizes auxin distribution in various plant tissues. We designed this probe to be transported by auxin transporters while lacking the ability to elicit auxin signaling. Using BODIPY as the fluorophore provides bright and stable fluorescence signals, making it suitable for live-imaging under standard fluorescent microscopy. We tested the probe with auxin reporter lines in Arabidopsis and performed yeast two-hybrid assays. The results showed that BODIPY-IAA2 did not activate auxin signaling through the auxin receptor TIR1. However, BODIPY-IAA2 did mildly compete with both exogenous and endogenous auxins for transport, indicating that the probe is transported by auxin transporters in vivo. The probe not only enables visualization of its tissue distribution but also allows sub-cellular staining, including the endoplasmic reticulum and tip regions in elongating cells in moss. We also observed unusual staining patterns in the main root of non-model parasitic plants where genetic transformation is not feasible. Our new fluorescent auxin probe demonstrates significant potential for detailed studies on auxin transport and distribution across diverse plant species.

plant biology↗

A transphyletic study of metazoan β-catenin protein complexes

{beta}-catenin is essential for various biological processes, such as body axis determination and cell differentiation, during embryonic development in metazoans. {beta}-catenin functions are thought to be exerted through complexes formed with various types of proteins. Although {beta}-catenin complex proteins have been identified in several bilaterians, little is known about the structural and functional properties of {beta}-catenin complexes in early metazoan evolution. In this study, we performed a comparative analysis of {beta}-catenin sequences in nonbilaterian lineages that diverged early in metazoan evolution. We also carried out transphyletic function experiments with {beta}-catenin from nonbilaterian metazoans using developing Xenopus embryos, which included secondary axis induction in embryos and proteomic analysis of {beta}-catenin protein complexes. Comparative functional analysis of nonbilaterian {beta}-catenins demonstrated sequence characteristics important for {beta}-catenin functions, and the deep origin and evolutionary conservation of the cadherin-catenin complex. Proteins co-immunoprecipitated with {beta}-catenin included several proteins conserved among metazoans. These data provide new insights into the conserved repertoire of {beta}-catenin complexes.

evolutionary biology↗

Neuronal and non-neuronal functions of the synaptic cell adhesion molecule, neurexin, in Nematostella vectensis.

The transition from diffusion-mediated cell-cell communication to faster and more targeted synaptic signaling in animal nervous systems has long been of interest to evolutionary biologists. Although genome sequencing of early-diverging metazoans has revealed the broad distribution of synapse-related genes among them, synaptic structures have been observed only in Cnidaria, the sister group to Bilateria. How synaptic machinery evolved remains largely unknown. In this study, we investigated the function of neurexins (Nrxns), a core family of presynaptic cell adhesion molecules with critical roles in bilaterian chemical synapses, using the cnidarian model, Nematostella vectensis. Neural Nrxns, named delta-Nrxns, are expressed mainly in neuronal cell clusters that exhibit both peptidergic and classical neurotransmitter signaling. Knockdown of Nrxn{delta} genes reduced spontaneous peristalsis of N. vectensis polyps. Interestingly, gene knockdown and pharmacological studies suggested that Nrxn{delta} is involved in glutamate- and glycine-mediated signaling rather than peptidergic signaling. Knockdown of the epithelial Nrxn in N. vectensis revealed a major role in cell adhesion, particularly between ectodermal and endodermal epithelia. Overall, this study provides molecular, functional, and cellular insights into the ancestral, non-neural function of Nrxns, as well as key information for understanding how and why this family of cell adhesion molecules was recruited to synaptic machinery.

evolutionary biology↗

A high-sensitivity ELISA for detection of human FGF18 in culture supernatants from tumor cell lines

Fibroblast growth factor 18 (FGF18) is elevated in several human cancers, such as gastrointestinal and ovarian cancers, and stimulates the proliferation of tumor cells. This suggests that FGF18 may be a promising candidate biomarker in cancer patients. However, the lack of a high-sensitivity enzyme-linked immunosorbent assay (ELISA) does not permit testing of this possibility. In this study, we generated monoclonal antibodies against human FGF18 and developed a high-sensitivity ELISA to measure human FGF18 at concentrations as low as 10 pg/mL. Of the eight tumor cell lines investigated, we detected human FGF18 in culture supernatants from four tumor cell lines, including HeLa, OVCAR-3, BxPC-3, and SW620 cells, albeit the production levels were relatively low in the latter two cell lines. Moreover, the in-house ELISA could detect murine FGF18 in sera from mice overexpressing murine Fgf18 in hepatocytes, although the sensitivity in detecting murine FGF18 was relatively low. This FGF18 ELISA could be a valuable tool to validate FGF18 as a potential biomarker for cancer patients and to test the contribution of FGF18 for various disease models in vivo and in vitro.

cancer biology↗

Mesophyll specific expression of a bacterial mercury transporter-based vacuolar sequestration machinery sufficiently enhances mercury tolerance of Arabidopsis.

We aimed to efficiently enhance plant Hg(II) tolerance by the transgenic approach utilizing a bacterial mercury transporter MerC, an Arabidopsis mesophyll specific promoter pRBCS1A, and a vacuolar membrane targeting syntaxin AtVAM3/SYP22. We generated two independent homozygous Arabidopsis pRBCS1A-TCV lines expressing mT-Sapphire-MerC-AtVAM3 under the control of pRBCS1A. Quantitative RT-PCR showed that the transgene was expressed specifically in shoots of pRBCS1A-TCV lines. Confocal analyses further demonstrated the leaf mesophyll specific expression of mT-Sapphire-MerC-AtVAM3. Confocal observation of the protoplast derived from the F1 plants of the pRBCS1A-TCV line and the tonoplast marker line p35S-GFP-{delta}TIP showed the tonoplast colocalization of mT-Sapphire-MerC-AtVAM3 and GFP-{delta}TIP. These results clearly demonstrated that mT-Sapphire-MerC-AtVAM3 expression in Arabidopsis is spatially regulated as designed at the transcript and the membrane trafficking levels. We then examined the Hg(II) tolerance of the pRBCS1A-TCV lines as well as the p35S-driven MerC-AtVAM3 expressing line p35S-CV under the various Hg(II) stress conditions. Short-term (12 d) Hg(II) treatment indicated the enhanced Hg(II) tolerance of both pRBCS1A-TCV and p35S-CV lines. The longer (3 weeks) Hg(II) treatment highlighted the better shoot growth of the transgenic plants compared to the wild-type Col-0 and the pRBCS1A-TCV lines were more tolerant to Hg(II) stress than the p35S-CV line. These results suggest that mesophyll-specific expression of MerC-AtVAM3 is sufficient or even better to enhance the Arabidopsis Hg(II) tolerance. The Hg accumulation in roots and shoots did not differ between the wild-type Col-0 and the MerC-AtVAM3 expressing plants, suggesting that the boosted Hg(II) tolerance of the transgenic lines would be attributed to vacuolar Hg-sequestration by the tonoplast-localized MerC. Further perspectives of the MerC-based plant engineering are also discussed.

plant biology↗

Centriole and PCM cooperatively recruit CEP192 to spindle poles to promote bipolar spindle assembly

The pericentriolar material (PCM) that accumulates around the centriole expands during mitosis and nucleates microtubules. While centrosomes facilitate bipolar spindle formation, the individual functions of the centriole and PCM in mitosis remain elusive. Herein, we show the redundant roles of the centriole and PCM in bipolar spindle formation in human cells. Upon depletion of the PCM scaffold components, pericentrin and CDK5RAP2, centrioles remained able to recruit CEP192 onto their walls, which was sufficient for bipolar spindle formation. In contrast, through centriole removal, we found that pericentrin and CDK5RAP2 recruited CEP192 at the acentriolar spindle pole and facilitated bipolar spindle formation in mitotic cells with one centrosome. Furthermore, the chemical perturbation of polo-like kinase 1, a critical kinase for PCM assembly, efficiently suppressed the proliferation of various cancer cell lines from which centrioles were removed. Overall, these data suggest that the centriole and PCM cooperatively recruit CEP192 to spindle poles and facilitate bipolar spindle formation in human cells.

cell biology↗

CLOCK/BMAL1 interferes with segmentation clock oscillation in mouse embryonic organoids

In mammals, circadian clocks are strictly suppressed during early embryonic stages as well as pluripotent stem cells, by the lack of CLOCK/BMAL1 mediated circadian feedback loops. During ontogenesis, the innate circadian clocks emerge gradually at a late developmental stage, then, with which the circadian temporal order is invested in each cell level throughout a body. Meanwhile, in the early developmental stage, a segmented body plan is essential for an intact developmental process and somitogenesis is controlled by another cell-autonomous oscillator, the segmentation clock, in the posterior presomitic mesoderm (PSM). In the present study, focusing upon the interaction between circadian key components and the segmentation clock, we investigated the effect of the CLOCK/BMAL1 on the segmentation clock Hes7 oscillation, revealing that the expression of functional CLOCK/BMAL1 severely interferes with the ultradian rhythm of segmentation clock in induced PSM and gastruloids. RNA sequencing analysis showed that the premature expression of CLOCK/BMAL1 affects the Hes7 transcription and its regulatory pathways. These results suggest that the suppression of CLOCK/BMAL1-mediated transcriptional regulation during the somitogenesis may be inevitable for intact mammalian development.

developmental biology↗

Hoxa10 mediates positional memory to govern stem cell function in adult skeletal muscle

Skeletal muscle stem cells (satellite cells) are distributed throughout the body with heterogeneous properties that corresponds to region-specific pathophysiology. However, topographical genes that have functions remain unidentified in satellite cells of adult muscle. Here, we showed that expression of Homeobox (Hox)-A cluster genes, key regulators of the embryonic body plan, was robustly maintained in both muscles and satellite cells in adult mice and humans, which recapitulates their embryonic origin. We observed that regionally specific expressed Hox genes were linked to hypermethylation of the Hox-A locus. We examined Hoxa10 inactivation in satellite cells and found it led to genomic instability and mitotic catastrophe, which resulted in a decline in the regionally specific regenerative ability of muscles in adult mice. Thus, our results showed that Hox gene expression profiles instill the embryonic history in satellite cells as positional memory, potentially modulating the region-specificity in adult skeletal muscles.

developmental biology↗

Nuclear GAPDH signaling mediates pathological cardiac hypertrophy

Here we report that stress-induced nuclear translocation of GAPDH mediates heart hypertrophy via Brahma-Related-Gene-1 (BRG1)-associated chromatin remodelling. In response to pressure overload elicited by transverse aortic constriction, we observed nuclear translocation of GAPDH in the mouse heart. We also demonstrated a robust nuclear localization of GAPDH in cardiomyocytes from patients with dilated hypertrophic cardiomyopathy, whereas negligible GAPDH in the nucleus in control subjects. This is the first demonstration of disease-associated nuclear GAPDH directly in living patients. Using immunohistochemical methods and a pharmacological way that selectively blocks GAPDH nuclear translocation (RR compound), we proved the causal involvement of GAPDH cysteine-150 modification in this translocation in Gq-induced cell model for heart hypertrophy. Accordingly, both pharmacological and genetic interventions proved that the same mechanism played a causal role for heart hypertrophy and dysfunction in vivo. We discovered that, upon nuclear translocation, GAPDH augmented the protein interaction of BRG1 and histone deacetylase 2 (HDAC2), which further facilitated the Myh7/Myh6 isoform ratio from the mature to immature status, an essential mechanism for heart hypertrophy. Beyond medical implications, we provide a novel mechanism of stress-induced reversion of a cellular phenotype from adult to fetal state, which is mediated by a "moonlighting" function of GAPDH.

molecular biology↗

Covalent Aurora A regulation by the metabolic integrator coenzyme A

Aurora A is a cell cycle protein kinase implicated in multiple human cancers, and several Aurora A-specific kinase inhibitors have progressed into clinical trials. In this study, we report structural and cellular analysis of a novel biochemical mode of Aurora A inhibition, which occurs through reversible covalent interaction with the universal metabolic integrator coenzyme A (CoA). Mechanistically, the CoA 3-phospho ADP moiety interacts with Thr 217, an Aurora A selectivity filter, which permits the formation of an unprecedented covalent bond with Cys 290 in the kinase activation segment, lying some 15 [A] away. CoA modification (CoAlation) of endogenous Aurora A is rapidly induced by oxidative stresses at Cys 290 in human cells, and microinjection of CoA into mouse embryos perturbs meitoic spindle formation and chromosome alignment. Aurora A regulation by CoA reveals how targeting of Aurora A might be accomplished in the future by development of a double-anchored covalent inhibitor.

biochemistry↗

Structural instability of IκB kinase β promotes autophagic degradation through enhancement of Keap1 binding

IKK{beta}, an essential kinase of NF-[kcy]B signaling, is composed of an N-terminal kinase domain (KD) and a C-terminal scaffolding domain, containing a ubiquitin-like domain (ULD). The Hsp90 chaperon has special responsibility for folding of protein kinases including IKK{beta}. Here, we found that Hsp90 inhibition induced IKK{beta} degradation, which is partially mediated by Keap1. Geldanamycin (GA), a Hsp90 inhibitor, enhances association of IKK{beta} with Keap1 through the binding site in KD, and translocates IKK{beta} to detergent-insoluble fractions leading its autophagic degradation. An electrophile tBHQ suppressed Keap1-mediated proteasomal Nrf2 degradation but not autophagic IKK{beta} degradation. Substitution mutation of Leu353 to Ala in the ULD destabilizes IKK{beta}, enhances its association with Keap1, translocates it to detergent-insoluble fractions, and causes its autophagic degradation. These results suggest that Keap1 is involved in the degradation of structural destabilized IKK{beta} and negative regulation of NF-[kcy]B under proteotoxic stress.

biochemistry↗