Biology subjects

Yamashiro, T.

Publications and source records attributed to Yamashiro, T..

12 recordsLinked to original sources

bioRxiv2026

Retinoid signaling promotes frontonasal identity while repressing maxillary identity during craniofacial development

Vertebrate facial development depends on the correct specification of embryonic facial prominences, a process known to be governed by region-specific reciprocal signaling pathways between the craniofacial ectoderm, endoderm and mesenchyme. This process is further modulated by transcriptional and epigenetic mechanisms that regulate the expression of essential genes in mesenchymal progenitors derived from cranial neural crest cells. Retinoid signaling plays a critical role in facial development, and both gain-and loss-of-function results in a wide spectrum of facial defects, including orofacial clefts. In this study, we identified retinoid signaling as a critical regulator of cranial neural crest cell specification toward a frontonasal process identity in mice. Rdh10 oxidizes vitamin A (all-trans retinol) to retinal, which is a rate limiting step in the synthesis of retinoic acid. Rdh10 loss-of-function resulted in ectopic formation of whisker pads - a derivative of the maxillary process - within the frontonasal process region. This transformation was evidenced by the mis-expression of maxillary specific transcription factors including Meis2 and Lhx6 in the frontonasal mesenchyme. Furthermore, these transcription factors exhibited increased chromatin accessibility at their consensus binding sites following the loss of retinoid signaling in frontonasal cranial neural crest cells. These results indicate that retinoid signaling acts as a critical regulator specifying frontonasal identity and fate of cranial neural crest cells as they migrate into the frontonasal process, while concomitantly repressing maxillary process fate. These results not only advance our understanding of frontonasal prominence specification and the evolutionary development of craniofacial structures but also offers valuable insights into the etiology and pathogenesis of craniofacial malformations such as orofacial clefts.

developmental biology↗

bioRxiv2026

IMAS enables target-aware integration of tumour multiomics to resolve communication-guided regulatory mechanisms

Tumour single-cell datasets contain weak, sparse and context-restricted regulatory signals that are difficult to distinguish from noise using expression measurements alone. Here we present IMAS, an integrative multiomic augmentation system that learns transferable regulatory structure from a pan-cancer foundation of matched single-cell RNA and chromatin-accessibility profiles and adapts it to data-limited target datasets. We refer to the resulting target-specific regulatory architectures as multi-layer target dependencies (MLTDs). MLTDs prioritize signals that remain supported across coordinated molecular, communication and perturbation-sensitive evidence, rather than by expression magnitude or any single prediction score. Rather than replacing the observed expression matrix, IMAS adds an interpretable regulatory-support layer for mechanism discovery. Across independent tumour datasets, IMAS preserved matched cross-layer supervision, concentrated predictive support into compact target-aligned structures and improved recovery of RNA and transcription-factor states. In colorectal cancer, MLTDs resolved a SOD2-associated perturbation-sensitive architecture that was distinct from native expression, conventional co-expression and the inherited pan-cancer hierarchy. These dependencies promoted propagation of perturbation-associated information through RNA-TF-regulatory-element bridges and into receiver-TF-aware communication across malignant cell states. A LAMB1-centred analysis further showed that successive regulatory, communication and temporal constraints restored an expected extracellular-matrix programme that was weakly represented in the original matrix. In head and neck squamous cell carcinoma, SOX2-centred MLTDs resolved malignant-state-specific perturbation programmes. In renal cancer, MLTD-guided analysis identified tumour-vascular coupling associated with spatially localized endothelial-to-mesenchymal-transition-like states in Xenium data. Together, IMAS reframes tumour multiomic augmentation as the recovery of compact, target-specific regulatory architectures rather than expression-matrix completion, providing an interpretable framework for prioritizing experimentally tractable mechanisms in heterogeneous tumour systems.

bioinformatics↗

bioRxiv2026

A Wnt-responsive fibrocartilage progenitor system coordinates postnatal mandibular condylar cartilage growth

Postnatal growth of the mandibular condyle requires coordinated expansion of fibrocartilage and production of chondrocytes, yet the cellular populations that organize this process remain incompletely defined. Here we identify a Wnt-responsive fibrocartilage progenitor population that contributes to postnatal mandibular condylar cartilage growth. Using a direct Wnt activity reporter (R26-WntVis), inducible genetic lineage tracing (Axin2CreERT2), and single-cell transcriptomics, we define a Wnt-enriched progenitor-like cluster localized predominantly within the fibrocartilage zone. Lineage tracing demonstrates that Axin2-lineage cells expand laterally within fibrocartilage and generate vertically aligned chondrocytes in the chondrocartilage compartment, indicating bidirectional growth contribution in vivo. Conditional ablation of {beta}-catenin in Axin2-lineage cells results in depletion of the fibrocartilage compartment and premature activation of chondrogenic differentiation programs, whereas constitutive {beta}-catenin activation disrupts compartmental organization without enhancing proliferation. Mechanistically, we identify Foxm1 as a Wnt-associated proliferative mediator enriched in fibrocartilage, and genetic reduction of Foxm1 cooperates with {beta}-catenin deficiency to impair condylar growth. In parallel, {beta}-catenin loss derepresses TGF-{beta}-Smad signaling and enhances chondrogenic differentiation, indicating that canonical Wnt activity coordinates proliferative maintenance while restraining lineage commitment within the same cellular compartment. Together, these findings identify a Wnt-responsive fibrocartilage progenitor system that regulates postnatal mandibular condylar cartilage growth by coupling Foxm1-associated proliferative maintenance with suppression of TGF-{beta}-dependent chondrogenic differentiation during temporomandibular joint development. Graphical abstractWnt-responsive fibrocartilage progenitors coordinate postnatal mandibular condylar cartilage growth through Foxm1-dependent proliferative maintenance and suppression of TGF-{beta}-driven chondrogenic differentiation.

developmental biology↗

bioRxiv2025

TMEM2 maintains hyaluronan turnover and cartilage homeostasis during early osteoarthritis progression

Osteoarthritis (OA) is a degenerative joint disease characterized by progressive disruption of the cartilage extracellular matrix (ECM), yet the molecular mechanisms governing ECM turnover during disease initiation remain incompletely defined. Hyaluronan (HA) is a major structural component of articular cartilage, and its regulated turnover is essential for maintaining tissue integrity. Transmembrane protein 2 (TMEM2) is a cell-surface hyaluronidase capable of degrading high-molecular weight HA under physiological conditions, but its role in joint tissues has remained unclear. Here, we examine the spatiotemporal expression and functional contribution of TMEM2 in articular cartilage using single-cell transcriptomic analysis, histological approaches, and a chondrocyte-specific conditional knockout mouse model. Under physiological conditions, Tmem2 was predominantly expressed in non-calcified articular chondrocytes. Following joint destabilization, Tmem2 expression was transiently increased during early osteoarthritis, coinciding with reduced cartilage HA content, consistent with altered HA turnover. Importantly, genetic ablation of Tmem2 in chondrocytes markedly exacerbated osteoarthritis progression, resulting in accelerated cartilage delamination, increased chondrocyte apoptosis, reduced proliferative activity, and enhanced hypertrophic differentiation. These changes occurred without detectable abnormalities in the synovium, subchondral bone, or osteophyte formation, indicating a cartilage-intrinsic phenotype. Collectively, these findings identify TMEM2 as an important regulator of hyaluronan homeostasis within the cartilage ECM and provide in vivo genetic evidence that TMEM2- dependent HA turnover contributes to the maintenance of articular cartilage integrity during osteoarthritis progression.

molecular biology↗

bioRxiv2024

SLC35G1: A highly chloride-sensitive transporter responsible for the basolateral membrane transport in intestinal citrate absorption

The intestinal absorption of essential nutrients, especially those not readily biosynthesized, is a critical physiological process for maintaining homeostasis. Numerous studies have indicated that intestinal absorption is mediated by various membrane transporters. Citrate, a crucial bioactive compound produced as an intermediate in the Krebs cycle, is absorbed in the small intestine through carrier-mediated systems because of its high hydrophilicity. While the luminal absorption of citrate is mediated by Na+-dicarboxylate cotransporter 1 (NaDC1/SLC13A2), the mechanism governing the release of the transported citrate into the bloodstream remains unknown. Here, we explored the transporters responsible for intestinal citrate absorption at the basolateral membrane, focusing on highly expressed orphan transporters in the small intestine as candidates. Consequently, SLC35G1, originally identified as a partner of stromal interaction molecule 1, a cell surface transmembrane glycoprotein, was found to play a role in the intestinal absorption of citrate at the basolateral membrane. Furthermore, our results revealed that SLC35G1-mediated citrate transport was diminished by chloride ions at physiologically relevant extracellular concentrations. This suggests that SLC35G1, to our best knowledge, is the first transporter identified to be extremely sensitive to chloride ions among those functioning on the basolateral membrane of intestinal epithelial cells. This study provides valuable insights into the intestinal absorption of citrate and significantly contributes to elucidating the poorly understood molecular basis of the intestinal absorption system.

physiology↗

bioRxiv2024

Compromised actin dynamics underlie the orofacial cleft in Baraitser-Winter Cerebrofrontofacial Syndrome with a variant in ACTB

Craniofacial anomalies encompassing the orofacial cleft are associated with >30% of systemic congenital malformations. Baraitser-Winter Cerebrofrontofacial syndrome (BWCFF) is a rare genetic disorder attributed to variants in the actin beta (ACTB) or actin gamma genes that are correlated with a range of craniofacial abnormalities, including cleft lip and/or palate. The underlying pathological mechanism of BWCFF remains elusive, and it is necessary to investigate the etiology of orofacial clefts in BWCFF. In this study, we identified a missense variant (c.1043C>T: p.S348L) in the ACTB gene from a patient with BWCFF and concomitant cleft lip and palate. Furthermore, we performed functional assessments of this variant using various disease models such as the MDCK cell line and Xenopus laevis. These models revealed a compromised capacity of mutated ACTB to localize at the epithelial junction, consequently affecting the behavior of epithelial cells. Additionally, we made the noteworthy discovery that mutated ACTB exhibited an impaired ability to bind PROFILIN1, a critical factor in actin polymerization. This defective ability may contribute to the molecular etiology of aberrant epithelial cell adhesion and migration, resulting in orofacial cleft formation in BWCFF. Author SummaryAdvances in clinical sequencing have rapidly elucidated the genetic basis of rare diseases affecting multiple organs. In this study, we investigate the role of a variant in the ACTB gene, which is fundamental to cell structure, in causing orofacial clefts in the Baraitser-Winter Cerebrofrontofacial Syndrome (BWCFF), known for its distinctive facial anomalies. Using epithelial cell lines and frog embryo models, we investigated the effects of the ACTB gene alteration on cellular functions. Our results indicate that this genetic change disrupts the normal adhesion and movement of epithelial cells, processes that are critical for facial development. This research underscores the importance of the ACTB gene in shaping the face and suggests new directions for future research, potentially informing the diagnosis and treatment of BWCFF and related conditions.

genetics↗

bioRxiv2024

The Role of Morphological Adaptability in Vibrio cholerae's Motility and Pathogenicity

Vibrio cholerae, the etiological agent of cholera, exhibits remarkable adaptability to different environmental conditions by undergoing morphological changes that significantly contribute to its pathogenicity and impact the epidemiology of the disease globally. This study investigates the morphological adaptability of the clinically isolated V. cholerae O1 strain, specifically focusing on the motility and pathogenicity differences between the filamentous and original comma-shaped forms within diverse viscosity conditions. Utilizing the El Tor strain of V. cholerae O1, we induced the transformation into the filamentous form and performed a comparative analysis with the canonical comma-shaped morphology. Our approach involved assessing motility patterns, swimming speeds, rotation rates, kinematics, and reversal frequencies through dark-field microscopy and high-speed imaging techniques. The findings reveal that filamentous V. cholerae cell retains enhanced motility in viscous environments. This suggests an evolutionary adaptation enabling survival across a range of habitats, notably the human gastrointestinal tract. Filamentous forms demonstrated increased reversal behavior at mucin interfaces, hinting at an advantage in penetrating the mucus layer. Rabbit intestinal loop assays further showed that both morphological forms exhibit similar fluid accumulation ratios, thus indicating comparable pathogenic potentials. These results underscore the significance of V. choleraes morphological flexibility in adapting to environmental viscosity changes, shedding light on the bacteriums intricate survival and infection strategies. Our study provides critical insights into the dynamics of cholera, underlining the importance of considering bacterial morphology in developing effective cholera control strategies.

microbiology↗

bioRxiv2024

Filamin A mediates embryonical palatal fusion by linking mechanotransduction with β-Catenin/Smad2

To decipher potential mechanisms underlying cleft palate (CP), we used advanced bioinformatic integrated with literature mining and genome-wide association study (GWAS). Re-analysis of RNA-seq data (GSE45568, GSE185279) combined with literature mining highlighted the roles of Filamin A (Flna) and Epithelial-Mesenchymal Transition (EMT) in palatal development. Immunofluorescence of in vivo palatal shelves showed increased Flna in medial edge epithelial (MEE) cells and EMT cells located in an epithelial triangle. Inhibition of TGF-{beta} or RhoA and mechanical stimuli impacted Flna expression in ex vivo cultured palatal shelves. Re-analysis of scRNA-seq data (GSE155928) highlighted a correlation between Flna and Ctnnb1 in EMT cells. Flna knockdown affected {beta}-catenin/Smad2 expression in cultured palatal shelves and HaCaT cells. Epithelium-specific knockout of Flna delayed palatal fusion in female mice but not males. Mendelian randomization analysis suggested that parental habitual physical activity (HPA) was causally associated with lower risk of CP in their offspring. Together, these findings suggested that parental HPA could benefit their offsprings palatal development through Flna by linking mechanotransduction with the Wnt/TGF-{beta}/Smad signaling pathways during palatal fusion.

developmental biology↗

bioRxiv2023

SLC26A2-mediated sulfate metabolism is essential for the tooth development

The sulfate transporter gene SLC26A2 is responsible for diastrophic dysplasia, which represents skeletal dysplasia in humans. This highlights the importance of sulfate metabolism in skeletal formation. SLC26A2-related chondrodysplasia is also known to exhibit abnormalities in craniofacial and tooth development. Although the function of SLC26A2 in mammals has been investigated using genetic mouse models, the essential role of SLC26A2 during craniofacial and tooth development has not been elucidated. In this study, we demonstrate the pivotal roles of SLC26A2-mediated sulfate metabolism during tooth development. Analysis of Slc26a2 expression reveals that it is predominantly expressed in dental tissues, including odontoblasts and ameloblasts, during tooth development. Slc26a2 knockout mice (Slc26a2-KO-{Delta}exon2) exhibit a retrognathic upper jaw, small upper incisors, and hypoplasia of upper molars. Additionally, upper incisors and molars in Slc26a2-KO-{Delta}exon2 mice display flattened odontoblasts and nuclei that lack intracellular polarity. In contrast, tooth phenotype is not remarkable in lower incisors and molars. Furthermore, the expression of odontoblast differentiation markers, Dspp and Dmp1, is significantly decreased in the upper molars of Slc26a2-deficient mice. Ex vivo organ culture of tooth germs by implantation of Slc26a2-deficient tooth germs under the kidney capsule reveals hypoplasia of the dentin matrix as well as tooth root shortening. In vitro studies using human dental pulp stem cells (hDPSCs) show that the expression levels of Dspp and Dmp1 in shSlc26a2 knockdown cells are significantly decreased compared to control cells. Collectively, our data demonstrate that SLC26A2-mediated sulfate metabolism is essential for tooth development. This study may provide insight into the mechanisms underlying tooth abnormalities in patients with recessively inherited chondrodysplasias caused by mutations in the SLC26A2 gene.

developmental biology↗

bioRxiv2021

The cell surface hyaluronidase TMEM2 plays an essential role in mouse neural crest cell development and survival

Neural crest cells (NCCs) are a migratory population that gives rise to a diverse cell lineage, including the craniofacial complex, the peripheral nervous system, and a part of the heart. Hyaluronan (HA) is a major component of the extracellular matrix, and its tissue levels are dynamically regulated in during development. Although the synthesis of HA has been shown to exert substantial influence on embryonic morphogenesis, the functional importance of the catabolic side of HA turnover is poorly understood. Here, we demonstrate that the transmembrane hyaluronidase TMEM2 plays an essential role in NCC development and the morphogenesis of their derivatives. Wnt1-Cre-mediated Tmem2 knockout (Tmem2CKO) mice exhibit severe craniofacial and cardiovascular abnormalities. Analysis of Tmem2 expression using Tmem2 knock-in reporter mice reveals that Tmem2 is expressed at the site of NCC delamination in the neural tube and in Sox9-positive emigrating NCCs, suggesting that Tmem2 is critical for NCC development. Consistent with this possibility, linage tracing analysis reveals that the contribution of Wnt1-Cre-labeled cells to NCC derivatives is significantly reduced in a Tmem2-deficient background. Moreover, the emigration of NCCs from the neural tube is greatly reduced in Tmem2CKO mice. In vitro assays demonstrate that Tmem2 expression is essential for the ability of mouse O9-1 NCCs to form focal adhesion on and migrate into HA-containing substrates. Tmem2CKO mice also exhibit increased apoptotic cell death in NCC-derived tissues. Collectively, our data demonstrate that Tmem2 is essential for normal development of NCC-derivatives, including the craniofacial complex, and that TMEM2-mediated HA degradation allows NCCs to generate a tissue environment suitable for efficient focal adhesion assembly and migration. This study reveals the hitherto unrecognized functional importance of the catabolic side of HA metabolism in embryonic development and highlights the pivotal role of Tmem2 in the process. Author SummaryThe functional significance of hyaluronan (HA) in embryonic developmental processes has been demonstrated by studies using genetic manipulation of HA synthesis. However, the expression of HA is regulated not only by its synthesis, but also by its degradation. This issue is of particular importance due to the extremely rapid metabolic turnover of HA. Curiously, mice with mutations/ablations of known hyaluronidase molecules, such as the lysosomal hyaluronidases HYAL1 and HYAL2, exhibit little embryonic phenotypes. This suggests the existence of yet another hyaluronidase molecule that plays a key role in regulating extracellular HA balance in developing tissues. In this context, transmembrane protein 2 (TMEM2) is a novel hyaluronidase that functions on the cell surface. Here, we demonstrate that TMEM2 is expressed at the site of neural crest development and in neural crest cell (NSC)-derived craniofacial tissue, and that NCC-targeted Tmem2 conditional knockout mice develop severe craniofacial defects, which attests to a requirement for TMEM2-mediated extracellular HA degradation in neural crest development. Our in vitro and in vivo analyses on the underlying mechanisms of the phenotype demonstrate that TMEM2 is essential for generating a tissue environment suitable for efficient focal adhesion formation by NCCs. This paper reveals for the first time that the catabolic machinery for HA exerts a specific regulatory role in embryonic morphogenesis, and that its dysregulation of HA degradation leads to severe developmental defects.

developmental biology↗

bioRxiv2021

Intracellular and intercellular gene regulatory networks inference from time-course individual RNA-Seq

Gene regulatory network (GRN) inference is an effective approach to understand the molecular mechanisms underlying biological events. Generally, GRN inference mainly targets intracellular regulatory relationships such as transcription factors and their associated targets. In multicellular organisms, there are both intracellular and intercellular regulatory mechanisms. Thus, we hypothesize that GRNs inferred from time-course individual (whole embryo) RNA-Seq during development can reveal intercellular regulatory relationships (signaling pathways) underlying the development. Here, we conducted time-course bulk RNA-Seq of individual mouse embryos during early development, followed by pseudo-time analysis and GRN inference. The results demonstrated that GRN inference from RNA-Seq with pseudo-time can be applied for individual bulk RNA-Seq similar to scRNA-Seq. Validation using an experimental-source-based database showed that our approach could significantly infer GRN for all transcription factors in the database. Furthermore, the inferred ligand-related and receptor-related downstream genes were significantly overlapped. Thus, the inferred GRN based on whole organism could include intercellular regulatory relationships, which cannot be inferred from scRNA-Seq based only on gene expression data. Overall, inferring GRN from time-course bulk RNA-Seq is an effective approach for understanding the regulatory relationships underlying biological events in multicellular organisms.

bioinformatics↗

bioRxiv2019

Anterior Cleft Palate due to Cbfb deficiency and its rescue by folic acid

Core binding factor {beta} (Cbfb) is a cofactor of Runx transcription factors. Among Runx transcription factors, Runx1 is a prerequisite for anterior-specific palatal fusion. However, whether Cbfb serves as a modulator or obligatory factor in Runx signaling that regulates palatogenesis is unclear. We herein report that Cbfb is essential and indispensable in anterior palatogenesis. Palatal fusion in Cbfb mutants is disturbed due to failed disintegration of the fusing epithelium specifically at the anterior portion, as is observed in Runx1 mutants. In this mutants, the Tgfb3 expression is disturbed at the corresponding area of the failed palatal fusion, where phosphorylation of Stat3 is also disturbed. TGFB3 protein rescues the palatal fusion in vitro. Strikingly, the anterior cleft palate in Cbfb mutants is further rescued by pharmaceutical application of folic acid that activates suppressed Stat3 phosphorylation and Tgfb3 expression in vitro. With these findings, we provide the first evidence that Cbfb is a prerequisite for anterior palatogenesis as an obligatory cofactor in the Runx1/Cbfb-Stat3-Tgfb3 signaling axis. Furthermore, the rescue of the mutant cleft palate using folic acid may elucidate potential therapeutic targets by Stat3 modification for the prevention and pharmaceutical intervention of cleft palate.\n\nSummary StatementEpithelial deletion of Cbfb results in an anterior cleft palate with impaired fusion of the palatal process and folic acid application rescues the mutant phenotype with Stat3 activation in vitro.

developmental biology↗