Biology subjects

Takahata, Y.

Publications and source records attributed to Takahata, Y..

3 recordsLinked to original sources

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↗

bioRxiv2022

Haploid-resolved and chromosome-scale genome assembly in hexa-autoploid sweetpotato (Ipomoea batatas (L.) Lam)

Sweetpotato (Ipomoea batatas (L.) Lam) is the worlds seventh most important food crop by production quantity. Cultivated sweetpotato is a hexaploid (2n = 6x = 90), and its genome (B1B1B2B2B2B2) is quite complex due to polyploidy, self-incompatibility, and high heterozygosity. Here we established a haploid-resolved and chromosome-scale de novo assembly of autohexaploid sweetpotato genome sequences. Before constructing the genome, we created chromosome-scale genome sequences in I. trifida using a highly homozygous accession, Mx23Hm, with PacBio RSII and Hi-C reads. Haploid-resolved genome assembly was performed for a sweetpotato cultivar, Xushu18 by hybrid assembly with Illumina paired-end (PE) and mate-pair (MP) reads, 10X genomics reads, and PacBio RSII reads. Then, 90 chromosome-scale pseudomolecules were generated by aligning the scaffolds onto a sweetpotato linkage map. De novo assemblies were also performed for chloroplast and mitochondrial genomes in I. trifida and sweetpotato. In total, 34,386 and 175,633 genes were identified on the assembled nucleic genomes of I. trifida and sweetpotato, respectively. Functional gene annotation and RNA-Seq analysis revealed locations of starch, anthocyanin, and carotenoid pathway genes on the sweetpotato genome. This is the first report of chromosome-scale de novo assembly of the sweetpotato genome. The results are expected to contribute to genomic and genetic analyses of sweetpotato.

genomics↗

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↗