Biology subjects

Saitoh, Y.

Publications and source records attributed to Saitoh, Y..

7 recordsLinked to original sources

bioRxiv2026

Anti-Nucleolin Aptamer iSN04 Inhibits Alveolar Rhabdomyosarcoma Cell Growth by Inducing Myogenic Differentiation

Rhabdomyosarcoma (RMS) is a muscle-derived soft tissue tumor that retains myogenic potential. Novel drugs for RMS are strongly needed because the standard chemotherapeutic agents for RMS, including vincristine (VCR), have marginally improved the survival rate of high-risk patients for several decades. An anti-nucleolin aptamer, iSN04, was originally identified to promote myogenic differentiation of myoblasts, and was subsequently reported to suppress the growth of embryonal RMS cells by potentiating their differentiation and arresting proliferation. The present study investigated the effects of iSN04 on two alveolar RMS cell lines, NRS-1 and RH30. iSN04 modulated gene expression levels such as myogenic transcription factors (MyoD and myogenin), inhibitor of differentiation proteins (ID1 and ID3), and the tumor suppressor CASZ1. iSN04 treatment induced NRS-1 cells to differentiate into contracting myotube-like cells, and severely impaired the ability of RH30 cells to form and grow tumorspheres in three-dimensional culture. Co-treatment with iSN04 and a low dose of VCR cooperatively suppressed the proliferation of RH30 cells compared with single-agent treatments. These data demonstrate that iSN04 can be a beneficial agent for RMS and hold potential for use in combination therapy with current standard drugs.

cell biology↗

bioRxiv2025

Splitting Hairs: Optimized Sample Preparation Strategy for Mass Spectrometry Imaging of Nematode Caenorhabditis elegans

Caenorhabditis elegans is a powerful model organism for studying development, neurobiology, aging, and toxicology, yet most investigations rely on genetic and phenotypic measurements that do not directly capture their biochemical landscape. Mass spectrometry (MS)-based metabolomics has begun to address this gap by enabling detection of small-molecule metabolites and lipids. However, conventional liquid or gas chromatography-MS approaches require homogenization of whole worms, eliminating spatial information. Mass spectrometry imaging (MSI) offers an avenue for visualizing metabolite distributions in situ, but its application to C. elegans is hindered by the nematodes small size and thick cuticle which make it challenging for structure preservation during cryo-sectioning and ion image interpretation. We develop an integrated sample preparation workflow to overcome these challenges and enable high-resolution MSI of C. elegans adult hermaphrodites. To facilitate anatomical and ion images interpretation, we employed a dual-fluorescent reporter strain expressing GFP in intestinal cells and RFP in neuronal nuclei. We optimized embedding media compositions and freezing strategies to preserve tissue architecture and genetically encoded reporter fluorescence during cryo-sectioning. Additionally, we implemented a simple "sandwiching" method that reproducibly orients worms, allowing consistent longitudinal sectioning. Using this optimized workflow, we achieved matrix-assisted laser desorption/ionization (MALDI) MSI of 10-m spatial resolution and demonstrated tissue-specific distributions of lipids and metabolites in adult hermaphrodites. With structural preservation, consistent orientation, and fluorescence-guided spatial annotation, our approach provides a foundation for investigating metabolic heterogeneity in C. elegans and can be adapted to other microscale biological systems for MSI applications.

biochemistry↗

bioRxiv2025

Human TIMELESS, a potential circadian clock regulator, plays an essential role in survival and reawakening of metastasis-initiating cells in bone

Bone metastasis is becoming increasingly common globally. In such cases, cancer cells disseminate from the primary site to bone, subsequently entering a dormant state. Following a certain incubation period, the cells reawaken and grow, forming a metastatic mass. These dormant cells are called metastasis-initiating cells (MICs), but their survival and reawakening are poorly understood. Here, we established an in vivo MIC-reawakening mouse model in bone. Microarray analysis demonstrated enrichment for mitochondrial oxidative phosphorylation (OXPHOS) and fatty acid synthesis in isolated MICs. In addition, transcriptional regulator TIMELESS was identified as an independent poor prognostic factor by using clinical transcriptomic datasets, which was validated by immunostaining on 209 breast cancer cases. TIMELESS-deficient breast, prostate, and bladder cancer cell lines exhibited reduced viability and MIC reawakening in bone. Single-cell analysis on the epigenetic landscape of MICs revealed that motif activities of CLOCK and BMAL1/ARNTL were enhanced in a cluster with increased TIMELESS accessibility scores. As TIMELESS regulates stemness through the OXPHOS metabolic state, an inhibitor targeting the metabolic pathway, MP-A08, was identified to suppress MIC reawakening and growth in bone more efficiently than cisplatin. These results suggest that TIMELESS regulates survival and reawakening in MICs and MP-A08 could contribute to adjuvant therapeutic strategies.

cancer biology↗

bioRxiv2025

Dynamics of biofilm-forming Bacillus subtilis in Caenorhabditis elegans gut

Biofilm-forming Bacillus subtilis strain NCIB3610 has been reported to show biofilm-mediated beneficial effects when fed to Caenorhabditis elegans, including enhanced stress resistance, extended lifespan, and protection against neurotoxic agents. However, biofilm-forming B. subtilis presents multiple cell types, and thus a thorough characterization of B. subtilis cell dynamics in the C. elegans gut in vivo is necessary to understand mechanisms of the biofilm-mediated beneficial effects. In this study, we utilized an isogenic NCIB3610 strain expressing a biofilm reporter PtapA-mKate2 to monitor matrix-producing components in C. elegans gut. Interestingly, our results revealed that in live C. elegans gut, no B. subtilis biofilms were formed but only free spores and diffused fluorescence, which were likely from dietary matrix-producing cells crushed by the pharynx. Additional data showed that spores can geminate into motile cells but not matrix-producing cells in living C. elegans gut. Biofilm formation was found in gut after C. elegans death, indicating that mechanistically, life-dependent functions of the worm inhibit the formation of matrix-producing cells in gut. These findings resolved a key piece of puzzle in understanding the fundamental mechanisms of C. elegans-B. subtilis interaction and highlighted the importance of characterizing cell dynamics in vivo in host-microbe interaction research.

physiology↗

bioRxiv2023

Activation of prefrontal parvalbumin interneurons ameliorates treatment-resistant working memory deficit even under continuous antipsychotic treatment in a mouse model of schizophrenia

BACKGROUNDOne of the critical unmet medical needs in schizophrenia is a remedy for cognitive deficits. However, the neural circuit mechanisms of them remain unresolved. In addition, despite the patients with schizophrenia cannot stop taking antipsychotics due to a high rate of discontinuation-induced relapse, previous studies using animal models of schizophrenia have not considered these clinical situations. METHODSHere, we employ multi-dimensional approaches, including histological analysis in the prelimbic cortex, LC-MS/MS-based in vivo dopamine D2 receptor occupancy analysis for antipsychotic drugs, in vivo calcium imaging and behavioral analyses of mice using chemogenetic manipulation, to investigate neural mechanisms and potential therapeutic interventions for working memory deficit in a mouse model with chronic phencyclidine (PCP) administration that resembles the schizophrenia symptomatology. RESULTSChronic PCP administration led to abnormalities in excitatory and inhibitory synapses, including dendritic spines of pyramidal neurons, vesicular glutamate transporter 1 (VGLUT1) positive terminals, and parvalbumin (PV) positive GABAergic interneurons, in layer 2-3 of the prelimbic cortex. Continuous olanzapine, which achieved a sustained therapeutic window of dopamine D2 receptor occupancy (60-80%) in the striatum, did not affect these synaptic abnormalities and working memory deficit in the PCP-treated mice. We found that the selective prelimbic PV activation, using hM3D(Gq)-DREADD system confirmed by in vivo calcium imaging, restored working memory deficit, even under continuous olanzapine treatment. CONCLUSIONSOur study raises a possibility that intervention in prefrontal PV neurons leads to an add-on therapy to antipsychotics targeting amelioration of treatment-resistant cognitive deficits in schizophrenia.

neuroscience↗

bioRxiv2022

A novel micro-ECoG recording method for recording multisensory neural activity from the parietal to temporal cortexes in mice

Characterization of inter-regional interactions in brain is essential for understanding the mechanism relevant to normal brain function and neurological disease. The recently developed flexible micro ()-electrocorticography (ECoG) device is one prominent method used to examine large-scale cortical activity across multiple regions. The sheet-shaped ECoG electrodes arrays can be placed on a relatively wide area of cortical surface beneath the skull by inserting the device into the space between skull and brain. Although rats and mice are useful tools for neuroscience, current ECoG recording methods in these animals are limited to the parietal region of cerebral cortex. Recording cortical activity from the temporal region of cortex in mice has proven difficult because of surgical barriers created by the skull and surrounding temporalis muscle anatomy. Here, we developed a sheet-shaped 64-channel ECoG device that allows access to the mouse temporal cortex, and we determined the factor determining the appropriate bending stiffness for the ECoG electrode array. We also established a surgical technique to implant the electrode arrays into the epidural space over a wide area of cerebral cortex covering from the barrel field to olfactory (piriform) cortex, which is the deepest region of the cerebral cortex. Using histology and computed tomography (CT) images, we confirmed that the tip of the ECoG device reached to the most ventral part of cerebral cortex without causing noticeable damage to the brain surface. Moreover, the device simultaneously recorded somatosensory and odor stimulus-evoked neural activity from dorsal and ventral parts of cerebral cortex in awake and anesthetized mice. These data indicate that our ECoG device and surgical techniques enable the recording of large-scale cortical activity from the parietal to temporal cortex in mice, including somatosensory and olfactory cortices. This system will provide more opportunities for the investigation of physiological functions from wider areas of the mouse cerebral cortex than those currently available with existing ECoG techniques.

neuroscience↗

bioRxiv2017

Adult Neurogenesis Conserves Hippocampal Learning Capacity

Memory coding strengthens synaptic efficacy in the hippocampus via a long-term potentiation (LTP)-like mechanism. Given that animals are able to store memories of everyday experiences, hippocampal circuits should be able to avoid saturation of overall synaptic weight to preserve learning capacity. However, the underlying mechanism for this is still poorly understood. Here, we show that adult neurogenesis in rats plays a crucial role in the maintenance of the hippocampal learning capacity for learning. Artificial saturation with hippocampal LTP impaired learning capacity in contextual fear conditioning, which then completely recovered after 14 days, when LTP had decayed to the basal level. Ablation of neurogenesis by X-ray irradiation delayed the recovery of learning capacity, while enhancement of neurogenesis using running wheel sped up the recovery. Thus, one benefit of ongoing adult neurogenesis is the maintenance of hippocampal learning capacity through homeostatic renewing of hippocampal memory circuits. Decreased neurogenesis in aged animals may underlie declines in cognitive function with aging.

neuroscience↗