Biology subjects

Sawada, A.

Publications and source records attributed to Sawada, A..

10 recordsLinked to original sources

bioRxiv2026

High-fat diet-induced obesity differentially alters circadian gene expression across peripheral tissues

Circadian rhythms regulate diverse physiological processes, including metabolism, and their disruption has been implicated in metabolic disorders such as obesity. However, the tissue-specific effects of obesity on peripheral circadian clocks remain incompletely understood. Here, we investigated the impact of high-fat diet (HFD)-induced obesity on circadian gene expression in skeletal muscle, liver, and white adipose tissue (WAT). Mice were fed either a regular diet (RD) or HFD for 6 weeks, followed by tissue collection at 4-hour intervals over a 24-hour period. Under RD conditions, key circadian regulators and their downstream targets exhibited robust 24-hour oscillations across all tissues. In contrast, HFD feeding induced distinct, tissue-specific alterations. In the liver, Per2, Dbp, and Rev-erb showed phase-advanced expression patterns, whereas in WAT, rhythmic expression was markedly attenuated. Notably, skeletal muscle largely preserved circadian gene expression patterns, indicating relative resistance to HFD-induced circadian disruption. In addition, HFD feeding altered metabolic gene expression in adipose tissue, characterized by reduced Pgc1 expression and increased Leptin expression. Together, these findings demonstrate that HFD-induced obesity differentially disrupts peripheral circadian clocks in a tissue-specific manner and highlight skeletal muscle as a relatively resilient tissue. These results provide insight into how circadian dysregulation contributes to metabolic abnormalities in obesity.

physiology↗

bioRxiv2024

Differential clearance rate of proteins encoded on a self-amplifying mRNA vaccine in muscle and lymph nodes

ARCT-154, a recently approved self-amplifying mRNA (saRNA) vaccine, has been shown in clinical trials to induce higher levels of neutralizing antibodies and sustain them for a longer time than the conventional mRNA vaccine BNT162b2. However, the scientific evidence explaining this superiority remain elusive. Hence, we explored the temporal changes in spike protein and replicase components following a single dose of ARCT-154 vaccination in mice. The encoded spike protein reached its highest level approximately 3 days after vaccination and quickly disappeared from the rectus femoris muscle, the injection site. Although the spike protein levels also peaked at an early time point in the lymph nodes, it remained detectable 28 days after the vaccination and then disappeared by 44 days after the vaccination. Expression of nsP1, nsP2 and nsP4 was observed in the injected muscle and/or the lymph nodes for up to 15 days post-vaccination. These data suggest that prolonged expression of spike proteins in lymph nodes may, if not entirely, be responsible for the induction of higher and prolonged levels of neutralizing antibodies by the saRNA vaccine.

molecular biology↗

bioRxiv2024

Ephrin Forward Signaling Controls Interspecies Cell Competition in Pluripotent Stem Cells

In the animal kingdom, evolutionarily conserved mechanisms known as cell competition eliminate unfit cells during development. Interestingly, cell competition also leads to apoptosis of donor cells upon direct contact with host cells from a different species during interspecies chimera formation. The mechanisms underlying how host animal cells recognize and transmit cell death signals to adjacent xenogeneic human cells remain incompletely understood. In this study, we developed an interspecies cell contact reporter system to dissect the mechanisms underlying competitive interactions between mouse and human pluripotent stem cells (PSCs). Through single-cell RNA-seq analyses, we discovered that Ephrin A ligands in mouse cells play a crucial role in signaling cell death to adjacent human cells that express EPHA receptors during interspecies PSC co-culture. We also demonstrated that blocking the Ephrin A-EPHA receptor interaction pharmacologically, and inhibiting Ephrin forward signaling genetically in the mouse cells, enhances the survival of human PSCs and promotes chimera formation both in vitro and in vivo. Our findings elucidate key mechanisms of interspecies PSC competition during early embryogenesis and open new avenues for generating humanized tissues or organs in animals, potentially revolutionizing regenerative medicine.

cell biology↗

bioRxiv2024

FGF2 promotes the expansion of parietal mesothelial progenitor pools and inhibits BMP4-mediated smooth muscle cell differentiation

Mesothelial cells, in the outermost layer of internal organs, are essential for both organ development and homeostasis. Although the parietal mesothelial cell is the primary origin of mesothelioma that may highjack developmental signaling, the signaling pathways that orchestrate developing parietal mesothelial progenitor cell (MPC) behaviors, such as MPC pool expansion, maturation, and differentiation, are poorly understood. To address it, we established a robust protocol for culturing WT1+ MPCs isolated from developing pig and mouse parietal thorax. Quantitative qPCR and immunostaining analyses revealed that BMP4 facilitated MPC differentiation into smooth muscle cells (SMCs). In contrast, FGF2 significantly promoted MPC progenitor pool expansion but blocked the SMC differentiation. BMP4 and FGF2 counterbalanced these effects, but FGF2 had the dominant impact in the long-term culture. A Wnt activator, CHIR99021, was pivotal in MPC maturation to CALB2+ mesothelial cells, while BMP4 or FGF2 was limited. Our results demonstrated central pathways critical for mesothelial cell behaviors.

developmental biology↗

bioRxiv2023

Generation of salivary glands derived from pluripotent stem cells via conditional blastocyst complementation

Various patients suffer from dry mouth due to salivary gland dysfunction. Whole salivary gland generation and transplantation is a potential therapy to resolve this issue. However, the lineage permissible to design the entire salivary gland generation has been enigmatic. Here, we discovered Foxa2 as a lineage critical for generating a salivary gland via conditional blastocyst complementation (CBC). Foxa2 linage, but not Shh nor Pitx2, initiated to label between the boundary region of the endodermal and the ectodermal oral mucosa before primordial salivary gland formation, resulting in marking the entire salivary gland. The salivary gland was agenesis by depleting Fgfr2 under the Foxa2 lineage in the mice. We rescued this phenotype by injecting donor pluripotent stem cells into the mouse blastocysts. Those mice survived until adulthood with normal salivary glands compatible in size compared with littermate controls. These results indicated that CBC-based salivary gland generation is promising for next-generation cell-based therapy.

developmental biology↗

bioRxiv2022

Foxa2 lineage+ mesendoderm forms a competitive pulmonary mesenchyme niche crucial for generating the entire lungs

Millions suffer from incurable lung diseases, and the donor lung shortage hampers organ transplants. Identifying the crucial lineage and the program for lung organogenesis could facilitate designing whole-lung bioengineering. Using lineage-tracing mice and human iPSC-derived lung-directed differentiation, we revealed that gastrulating Foxa2 lineage contributed to both lung mesenchyme and epithelium formation. Interestingly, Foxa2 lineage-derived cells in the lung mesenchyme progressively increased and occupied more than half of the mesenchyme niche, including endothelial cells, during lung development. Foxa2 promoter-driven, conditional Fgfr2 gene depletion caused the lung agenesis phenotype in mice. Importantly, wild-type donor mouse iPSCs injected into their blastocysts rescued this phenotype by complementing the Fgfr2-defective niche in the lung epithelium and mesenchyme. Donor cell is shown to replace the entire lung epithelial and robust mesenchymal niche during early chimeric lung development, resulting in efficient complementation of the nearly entire lung niche at the late stage of lung development. These results suggest that lung complementation based on the Foxa2 lineage is a unique model for the progressive mobilization of donor cells into both epithelial and mesenchymal lung niches and provides crucial insights for designing new bioengineering strategies to generate whole lungs.

developmental biology↗

bioRxiv2022

A developmental program that regulates mammalian organ size offsets evolutionary distance

Pigs are evolutionarily more distant from humans than mice, but their physiological organs are closest to humans. The molecular program leading to a more than 1,000-fold increase in organ size in pigs and humans over that of mice across evolution has not been elucidated. We generated large-scale transcriptional landscapes throughout swine lung development. Our cross-species single-cell molecular atlas let us discover swine progenitor identities, stage-specific markers, and a core organ-size regulation program (COSRP), well-conserved in swine and humans but less so in mice. Across eight mammalian species, human COSRP promoters showed higher homologies to evolutionary-distant large animals, including pigs, than evolutionary-close small animals. Our study provides a molecular foundation during swine lung development that unveils animal size regulation conserved in the COSRP promoter, independent of genome-wide evolution. COSRP is a critical paradigm for studying thousands-fold changes in biological sizes in evolution, development, cancer, zoology, respirology, organoids, and biotechnology, particularly human-compatible organ generation. One Sentence SummaryA cross-species developmental molecular atlas identified the indicator of lung and animal size beyond evolution

evolutionary biology↗

bioRxiv2021

Nasal delivery of single-domain antibodies improve symptoms of SARS-CoV-2 infection in an animal model

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the disease COVID-19 can lead to serious symptoms, such as severe pneumonia, in the elderly and those with underlying medical conditions. While vaccines are now available, they do not work for everyone and therapeutic drugs are still needed particularly for treating life-threatening conditions. Here, we showed nasal delivery of a new, unmodified camelid single-domain antibody (VHH), termed K-874A, effectively inhibited SARS-CoV-2 titers in infected lungs of Syrian hamsters without causing weight loss and cytokine induction. In vitro studies demonstrated that K-874A neutralized SARS-CoV-2 in both VeroE6/TMPRSS2 and human lung-derived alveolar organoid cells. Unlike other drug candidates, K-874A blocks viral membrane fusion rather than viral attachment. Cryo-electron microscopy revealed K-874A bound between the receptor binding domain and N-terminal domain of the virus S protein. Further, infected cells treated with K-874A produced fewer virus progeny that were less infective. We propose that direct administration of K-874A to the lung via a nebulizer could be a new treatment for preventing the reinfection of amplified virus in COVID-19 patients. Author summaryVaccines for COVID-19 are now available but therapeutic drugs are still needed to treat life-threatening cases and those who cannot be vaccinated. We discovered a new heavy-chain single-domain antibody that can effectively neutralize the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes COVID-19. Unlike other drug candidates, which prevent the virus from attaching to the receptor on the host cell, this new antibody acts by blocking the virus membrane from fusing with the host cell membrane. We studied the behavior of the new antibody in vitro using VeroE6/TMPRSS2 cells and human lung organoids. When delivered through the nose to infected Syrian hamsters, we found that this antibody could prevent the typical symptoms caused by SARS-CoV-2. Our results are significant because delivering simple drugs directly to infected lungs using a nebulizer could increase the potency of the drugs while reducing the risk of immune reaction that could occur if the drugs escape or are delivered through the blood stream.

microbiology↗

bioRxiv2018

Changes in clock gene expression in esophagus in rat reflux esophagitis

Background and AimsGastroesophageal reflux disease (GERD) is strongly associated with sleep disturbances. Clock genes harmonize circadian rhythms by their periodic expression and regulate several physiological functions. However, the association between clock genes and GERD is still unknown. We investigated whether reflux esophagitis affects circadian variability of clock genes in the esophagus and other organs using a rat reflux esophagitis model.\n\nMethodsReflux esophagitis was induced in 7-week-old male Wistar rats. Sham-operated rats were used as controls. Rats were sacrificed at 09:00 (light period) and 21:00 (dark period) 3 days (acute phase) and 21 days (chronic phase) after induction of esophagitis. The expression levels of clock gene mRNAs such as Per1, Per2, Per3, Cryl, Cry2, Arntl, and Clock in the esophagus were investigated by qPCR. Arntl expression was examined in stomach, small intestine, colon, and liver tissues. Serum melatonin and IL-6 levels were measured by ELISA.\n\nResultsHistological examination of reflux esophagitis mainly revealed epithelial defects with marked inflammatory cell infiltration in the acute phase, and mucosal thickening with basal cell hyperplasia in the chronic phase. Circadian variability of clock genes, except Cry1, was present in the normal esophagus, and was completely disrupted in reflux esophagitis during the acute phase. The circadian variability of Per2, Per3, and Arntl returned to normal, but disruption of Per1, Cry2, and Clock was present in the chronic phase. Disruption of circadian variability of Arntl was observed in the esophagus, as well as in the stomach, small intestine, and liver tissues in reflux esophagitis during the acute phase. There were no significant differences in serum melatonin and IL-6 levels between control and reflux esophagitis animals in both acute and chronic phases.\n\nConclusionDisruption to circadian variability of clock genes may play a role in the pathogenesis of GERD.

pathology↗

bioRxiv2017

The chromatin factor Gon4l regulates embryonic axis extension by promoting mediolateral cell polarity and notochord boundary formation through negative regulation of cell adhesion

Anteroposterior axis extension during vertebrate gastrulation requires cell proliferation, embryonic patterning, and morphogenesis to be spatiotemporally coordinated, but the underlying genetic mechanisms remain poorly understood. Here we define a role for the conserved chromatin factor Gon4l, encoded by ugly duckling (udu), in coordinating tissue patterning and axis extension during zebrafish gastrulation. Although identified as a recessive enhancer of short axis phenotypes in planar cell polarity (PCP) mutants, we found that Gon4l functions in a genetically independent, partially overlapping fashion with PCP signaling to regulate mediolateral cell polarity underlying axis extension in part by promoting notochord boundary formation. We identified direct genomic targets of Gon4l and found that it acts as both a positive and negative regulator of gene expression, including limiting expression of the cell-cell and cell-matrix adhesion molecules EpCAM and Integrin3b. Excess epcam or itga3b in wild-type gastrulae phenocopied notochord boundary defects of udu mutants, while downregulation of itga3b suppressed them. By promoting formation of this anteroposteriorly aligned boundary and associated cell polarity, Gon4l cooperates with PCP signaling to coordinate morphogenesis with the anteroposterior embryonic axis.

developmental biology↗