Biology subjects

Saito, M. K.

Publications and source records attributed to Saito, M. K..

7 recordsLinked to original sources

bioRxiv2026

In vivo xenogenic reconstitution of human alveolar epithelial architecture and function

An urgent need exists for lung models that accurately replicate human physiological profiles. We developed a chimeric mouse model enabling targeted ablation of alveolar type 2 (AT2) cells and lung macrophages, creating niches for endoscopically transplanted human induced pluripotent stem cell (hiPSC)-derived lung progenitors (hLPs). These engrafted cells were retained for 24 weeks, demonstrating self-renewal and differentiation potential, surfactant protein secretion, and maintaining alveolar phosphate homeostasis, suggesting their maturation into AT2 cells. Furthermore, transplantation of hLPs derived from disease-specific hiPSCs recapitulated the phenotype of pulmonary alveolar microlithiasis. The architecture, function, and metabolism of human alveolar epithelium were accurately replicated in vivo. This model has the potential to link experimental models and first-in-human studies, facilitating the development of novel therapies for intractable lung diseases.

developmental biology↗

bioRxiv2022

SMN promotes mitochondrial metabolic maturation during myogenesis by regulating the MYOD-miRNA axis.

Spinal muscular atrophy (SMA) is a congenital neuromuscular disease caused by the mutation or deletion of survival motor neuron 1 (SMN1) gene. Although the primary cause of progressive muscle atrophy in SMA has classically been considered the degeneration of motor neurons, recent studies have indicated a skeletal muscle-specific pathological phenotype such as impaired mitochondrial function and enhanced cell death. Here we found that the downregulation of SMN causes mitochondrial dysfunction and subsequent cell death in in vitro models of skeletal myogenesis with both a murine C2C12 cell line and human induced pluripotent stem cells. During myogenesis, SMN binds to the genome upstream of the transcriptional start sites of MYOD1 and microRNA (miR)-1 and -206. Accordingly, the loss of SMN downregulates these miRs, whereas supplementation of the miRs recovers the mitochondrial function, cell survival and myotube formation of SMN-deficient C2C12, indicating the SMN-miR axis is essential for myogenic metabolic maturation. Additionally, introduction of the miRs into ex vivo muscle stem cells derived from {Delta}7-SMA mice caused myotube formation and muscle contraction. In conclusion, our data revealed novel transcriptional roles of SMN during myogenesis, providing an alternative muscle-oriented therapeutic strategy for SMA patients. HighlightsO_LIReduced SMN causes mitochondrial dysregulation in myogenic cells. C_LIO_LIReduced SMN downregulates miR-1 and miR-206 expression in myogenic cells. C_LIO_LISMN protein binds to the genome upstream of MYOD1, miR-1 and miR-206. C_LIO_LImiR-1 and miR-206 are sufficient to improve skeletal muscle function in an SMA model. C_LI

cell biology↗

bioRxiv2021

Prediction of broad chemical toxicities using induced pluripotent stem cells and gene networks by transfer learning from embryonic stem cell data

The assessment of toxic chemicals using animals has limited applicability to humans. Moreover, from the perspective of animal protection, effective alternatives are also desired. Previously, we developed a method that combines developmental toxicity testing based on undifferentiated human embryonic stem (ES) cells (KhES-3) and gene networks. We showed that [≥] 95% accurate predictions could be achieved for neurotoxins, genotoxic carcinogens, and non-genotoxic carcinogens. Here, we expanded this method to predict broad toxicities and predicted the toxicity of 24 chemicals in six categories (neurotoxins, cardiotoxins, hepatotoxins, nephrotoxins [glomerular nephrotoxins/tubular nephrotoxins], and non-genotoxic carcinogens) and achieved high prediction accuracy (AUC = 0.90-1.00) in all categories. Moreover, to develop a testing system with fewer ethical issues, we screened for an induced pluripotent stem (iPS) cell line on the basis of cytotoxic sensitivity and used this line to predict toxicity in the six categories based on the gene networks of iPS cells using transfer learning from the ES cell gene networks. We successfully predicted toxicities in four toxin categories (neurotoxins, hepatotoxins, glomerular nephrotoxins, and non-genotoxic carcinogens) at high accuracy (AUC = 0.82-0.99). These results demonstrate that the prediction of chemical toxicity is possible even with iPS cells by transfer learning once a gene expression database has been developed from an ES cell line. This method holds promise for tailor-made safety evaluations using individual iPS cells.

pharmacology and toxicology↗

bioRxiv2021

Aberrant localization of CDC42 C-terminal variants to the Golgi apparatus drives pyrin inflammasome-dependent autoinflammation

Mutations in the C-terminal region of the CDC42 gene cause severe neonatal-onset autoinflammation. Elevated levels of serum IL-18 in patients and effectiveness of IL-1{beta}-blocking therapy indicate that the pathology involves abnormal inflammasome activation; however, the mechanism underlying autoinflammation remains to be elucidated. Using induced-pluripotent stem cells established from patients carrying CDC42R186C, we found that patient-derived cells secreted larger amounts of IL-1{beta} in response to pyrin-activating stimuli. Aberrant palmitoylation and localization of CDC42R186C protein to the Golgi apparatus promoted pyrin inflammasome assembly downstream of pyrin dephosphorylation. Aberrant subcellular localization was the common pathological feature shared by CDC42 C-terminal variants with inflammatory phenotypes, including CDC42*192C*24 that also localizes to the Golgi apparatus. Furthermore, the level of pyrin inflammasome overactivation paralleled that of mutant protein accumulation in the Golgi apparatus, but no that of the mutant GTPase activity. These results reveal an unexpected association between CDC42 subcellular localization and pyrin inflammasome activation that could pave way for elucidating the mechanism of pyrin inflammasome formation.

immunology↗

bioRxiv2019

Angiocrine factors from HUVECs amplify erythroid cells

Erythropoiesis is regulated by microenvironmental factors from the vasculature. Enhanced erythropoiesis, which occurs under stress or during development, amplifies erythroid cells to meet the demand of red blood cells. This process uncouples cell division and differentiation, thus the accumulated erythroid cells remain undifferentiated in the vasculature. However, little is known about how vascular endothelial cells (ECs) regulate erythropoiesis. Here we identified that human umbilical vein endothelial cells (HUVECs) keep erythroid cells undifferentiated and amplify their number. We determined that HUVECs amplify erythroid cells via secreted angiocrine factors. The expression profile of these factors suggested that they resemble macrophage-crines for enhanced erythropoiesis. Molecularly, HUVECs mediate the activation of ERK signaling. These data indicate that angiocrine factors from HUVECs enhance erythropoiesis via the amplification of undifferentiated erythroid cells. Our study contributes to the ultimate goal of harnessing erythropoiesis to replace blood transfusions.

developmental biology↗

bioRxiv2019

Biomimetic Aorta-Gonad-Mesonephros on-a-Chip to Study Human Developmental Hematopoiesis

We established a multilayer microfluidic Aorta-Gonad-Mesonephros (AGM)-on-a-chip to emulate developmental hematopoiesis from human pluripotent stem cells. We show that the AGM-chip efficiently derives endothelial-to-hematopoietic transition (EHT) in the presence of mesenchymal stroma and endothelial cells. The AGM-chip could dissect the cellular and molecular mechanisms of human developmental hematopoiesis.

bioengineering↗

bioRxiv2019

Modeling the Human Segmentation Clock with Pluripotent Stem Cells

Pluripotent stem cells (PSCs) have increasingly been used to model different aspects of embryogenesis and organ formation1. Despite recent advances in the in vitro induction of major mesodermal lineages and mesoderm-derived cell types2,3, experimental model systems that can recapitulate more complex biological features of human mesoderm development and patterning are largely missing. Here, we utilized induced pluripotent stem cells (iPSCs) for the stepwise in vitro induction of presomitic mesoderm (PSM) and its derivatives to model distinct aspects of human somitogenesis. We focused initially on modeling the human segmentation clock, a major biological concept believed to underlie the rhythmic and controlled emergence of somites, which give rise to the segmental pattern of the vertebrate axial skeleton. We succeeded to observe oscillatory expression of core segmentation clock genes, including HES7 and DKK1, and identified novel oscillatory genes in human iPSC-derived PSM. We furthermore determined the period of the human segmentation clock to be around five hours and showed the presence of dynamic traveling wave-like gene expression within in vitro induced human PSM. Utilizing CRISPR/Cas9-based genome editing technology, we then targeted genes, for which mutations in patients with abnormal axial skeletal development such as spondylocostal dysostosis (SCD) (HES7, LFNG and DLL3) or spondylothoracic dysostosis (STD) (MESP2) have been reported. Subsequent analysis of patient-like iPSC knock-out lines as well as patient-derived iPSCs together with their genetically corrected isogenic controls revealed gene-specific alterations in oscillation, synchronization or differentiation properties, validating the overall utility of our model system, to recapitulate not only key features of human somitogenesis but also to provide novel insights into diseases associated with the formation and patterning of the human axial skeleton.

developmental biology↗