Biology subjects

Ohnishi, H.

Publications and source records attributed to Ohnishi, H..

6 recordsLinked to original sources

bioRxiv2025

Identification of stem cell marker-positive subpopulations in the vocal fold of the larynx through transcriptomic analyses

Information on the maintenance of tissue homeostasis is important for the development of effective therapeutic methods, however, reports on the cellular composition and tissue stem cells of the larynx were scarce. Therefore, we analyzed mouse laryngeal mucosa using scRNA-seq, and spatial transcriptomics by photo-isolation chemistry, and performed the generation of laryngeal organoid used as an in vitro model from mouse laryngeal mucosa. As a result, we found a SOX9-positive basal cell subpopulation and a Lgr5-positive fibroblast subpopulation in the mouse vocal fold, and obtained three types of epithelial organoids from laryngeal epithelium. We also confirmed the differences in pseudostratified ciliated columnar epithelium composition between the supraglottis and subglottis of the mouse larynx. These findings provide novel insights and valuable tools for future research in laryngology and stem cell biology.

cell biology↗

bioRxiv2024

From Monomers to Oligomers: Structural Mechanism of Receptor-Triggered MyD88 Assembly in Innate Immune Signaling

MyD88 plays a pivotal role in Toll-like receptor (TLR) and interleukin-1 family signaling through its oligomerization upon receptor activation, leading to downstream protein recruitment. The Toll/interleukin-1 receptor domain of MyD88 (TIRMyD88) is responsible for this receptor-mediated oligomerization, but the detailed mechanism involved remains elusive. We investigated the structure of TIRMyD88 oligomers and their interactions with TLRs. Cryoelectron microscopy revealed that tandemly arrayed TIRMyD88 subunits formed an antiparallel double-stranded filament that could further form rings and cylindrical filaments. Moreover, the self-assembly of TIRMyD88 in vitro was markedly accelerated by dimeric rather than monomeric receptor TIRs, possibly reflecting the signal initiation step in vivo. High-speed atomic force microscopy further captured the dynamic processes of oligomerization of TIRMyD88, in addition to its direct interaction with the receptor TIRs. Based on these results, a novel regulatory mechanism of TIRMyD88 oligomerization underlying the signal initiation step was revealed.

biophysics↗

bioRxiv2023

Changes in cell morphology and function induced by NRAS Q61R mutation in lymphatic endothelial cells

Recently, a low-level somatic mutation in NRAS gene (c.182 A > G, Q61R) was identified in the specimens of patients with kaposiform lymphangiomatosis (KLA). However, it is unknown how these low-frequency mutated cells can affect the characterization and surrounding environment of their lesions. To understand the pathogenesis and association of these gene abnormalities, we established NRASQ61R mutated lymphatic endothelial cells (LECs) transfected with lentivirus vector and undertook morphological and functional characterization, protein expression profiling, and metabolome analysis. NRASQ61R human dermal LECs showed poor tube formation and high cell proliferation and migration ability with increasing ratios of mutated cells. Analysis of signaling pathways showed inactivation of the PIK3/AKT/mTOR pathway and hyperactivation of the RAS/MAPK/ERK pathway, which was improved by MEK inhibitor treatment. This study may show the theoretical circumstances in vitro induced by NRASQ61R-mutated cells in the affected lesions of KLA patients.

cell biology↗

bioRxiv2023

EBF1 limits the numbers of cochlear hair and supporting cells and forms the scala tympani and spiral limbus during the development of the inner ear

Early B-cell factor 1 (EBF1) is a basic helix-loop-helix transcription factor essential for the differentiation of various tissues. Our single-cell RNA sequencing data suggest that Ebf1 is expressed in the sensory epithelium of the inner ear. Here, we found that the Ebf1 gene and its protein are expressed in the prosensory domain of the inner ear, medial region of the cochlear floor, inner ear mesenchyme, and cochleo-vestibular ganglion. Ebf1 deletion results in incomplete formation of the spiral limbus and scala tympani, increased number of cells in the organ of Corti and Kollikers organ, and aberrant course of the spiral ganglion axons. The inner ear-specific deletion of Ebf1 revealed that scala tympani formation depended on Ebf1 expressed in the otic mesenchyme. Ebf1 deletion in the cochlear epithelia caused the proliferation of SOX2-positive cochlear cells at E13.5, indicating that EBF1 suppresses the proliferation of the prosensory domain and cells of Kollikers organ to facilitate the development of appropriate numbers of hair and supporting cells. Furthermore, mice with deletion of cochlear epithelium-specific Ebf1 showed poor postnatal hearing function. Our results suggest that Ebf1 is essential for normal auditory function in mammals.

developmental biology↗

bioRxiv2022

Single-cell RNA-seq reveals stepwise fate conversion of supporting cells to hair cells in the chick auditory epithelium

In contrast to mammals, the avian cochlea, specifically the basilar papilla, can regenerate sensory hair cells, which involves fate conversion of supporting cells to hair cells. To determine the mechanisms for converting supporting cells to hair cells, we used single-cell RNA sequencing during hair cell regeneration in explant cultures of chick basilar papillae. We identified dynamic changes in the gene expression of supporting cells, and the pseudotime trajectory analysis demonstrated the stepwise fate conversion from supporting cells to hair cells. Initially, supporting cell identity was erased and transition to the precursor state occurred. A subsequent gain in hair cell identity progressed together with downregulation of precursor-state genes. Transforming growth factor beta receptor 1-mediated signaling was involved in induction of the initial step, and its inhibition resulted in suppression of hair cell regeneration. Our data provide new insights for understanding fate conversion from supporting cells to hair cells in avian basilar papillae.

neuroscience↗

bioRxiv2018

Microglial SIRPα regulates the emergence of CD11c+ microglia and demyelination damage in white matter

A characteristic subset of microglia expressing CD11c appears in response to brain damage. However, the functional role of CD11c+ microglia, as well as the mechanism of its induction, are poorly understood. Here we report that the genetic ablation of signal regulatory protein (SIRP), a membrane protein, induced CD11c+ microglia in the brain white matter. Mice lacking CD47, a physiological ligand of SIRP, and microglia-specific SIRP knockout mice exhibited the same phenotype, suggesting the interaction between microglial SIRP and CD47 on neighbouring cells suppressed the emergence of CD11c+ microglia. A lack of SIRP did not cause detectable damage in the white matter, but resulted in the increased expression of genes characteristic of the repair phase after demyelination. In addition, cuprizone-induced demyelination was alleviated by the microglia-specific ablation of SIRP. Thus, microglial SIRP suppresses the induction of CD11c+ microglia that have the potential to accelerate the repair of damaged white matter.

neuroscience↗