Biology subjects

Fujii, W.

Publications and source records attributed to Fujii, W..

4 recordsLinked to original sources

bioRxiv2023

Protective role of protease-activated receptor-2 in anaphylaxis model mice

Anaphylaxis is a severe life-threatening hypersensitivity reaction induced by mast cell degranulation. Among the various mediators of mast cells, little is known about the role of tryptase. Therefore, we aimed to elucidate the role of protease-activating receptor-2 (PAR-2), a receptor activated by tryptase, in murine anaphylactic models using PAR-2-deficient mice and newly generated tryptase-deficient mice. Anaphylaxis was induced by IgE-dependent and IgE-independent mast cell degranulation in mice. PAR-2 deficiency exacerbated the decrease in body temperature and hypotension during anaphylaxis; however, the number of skin mast cells, degree of mast cell degranulation, and systemic and local vascular hyperpermeability were comparable in PAR-2 knockout and wild-type mice. Nitric oxide, which is produced by endothelial nitric oxide synthase (eNOS), is an indispensable vasodilator in anaphylaxis. In the lungs of anaphylactic mice, PAR-2 deficiency promoted eNOS expression and phosphorylation, suggesting a protective effect of PAR-2 against anaphylaxis by downregulating eNOS activation and expression. Based on the hypothesis that the ligand for PAR-2 in anaphylaxis is mast cell tryptase, tryptase-deficient mice were generated using CRISPR-Cas9. In wild-type mice, the PAR-2 antagonist exacerbated the body temperature drop due to anaphylaxis; however, the effect of the PAR-2 antagonist was abolished in tryptase-deficient mice. These results suggest that tryptase is a possible ligand of PAR-2 in anaphylaxis and that the tryptase/PAR-2 pathway attenuates the anaphylactic response in mice.

molecular biology↗

bioRxiv2021

Periosteum-derived podoplanin-expressing stromal cells regulate nascent vascularization during epiphyseal marrow development

Bone marrow development and endochondral bone formation occur simultaneously. During endochondral ossification, periosteal vasculatures and stromal progenitors invade the primary avascular cartilaginous anlage; this induces primitive marrow development. We previously determined that bone marrow podoplanin (PDPN)-expressing stromal cells exist in a perivascular microenvironment, and promote megakaryopoiesis and erythropoiesis. In this study, we aimed to examine the involvement of PDPN-expressing stromal cells in the postnatal bone marrow generation. We found that periosteum-derived PDPN-expressing stromal cells regulate vascularization during postnatal epiphyseal marrow development. Our findings suggest that these cells act as pericytes on the primitive vasculature of the nascent marrow. They invade the cartilaginous epiphysis and regulate marrow development and homeostasis by maintaining vascular integrity. To the best of our knowledge, this is the first study to comprehensively examine how PDPN-expressing stromal cells contribute to marrow development and homeostasis.

developmental biology↗

bioRxiv2020

Alterations of multiple alveolar macrophage states in chronic obstructive pulmonary disease

Despite the epidemics of chronic obstructive pulmonary disease (COPD), the cellular and molecular mechanisms of this disease are far from being understood. Here, we characterize and classify the cellular composition within the alveolar space and peripheral blood of COPD patients and control donors using a clinically applicable single-cell RNA-seq technology corroborated by advanced computational approaches for: machine learning-based cell-type classification, identification of differentially expressed genes, prediction of metabolic changes, and modeling of cellular trajectories within a patient cohort. These high-resolution approaches revealed: massive transcriptional plasticity of macrophages in the alveolar space with increased levels of invading and proliferating cells, loss of MHC expression, reduced cellular motility, altered lipid metabolism, and a metabolic shift reminiscent of mitochondrial dysfunction in COPD patients. Collectively, single-cell omics of multi-tissue samples was used to build the first cellular and molecular framework for COPD pathophysiology as a prerequisite to develop molecular biomarkers and causal therapies against this deadly disease.

systems biology↗

bioRxiv2018

Aggregation recovers developmental plasticity in mouse polyploid embryos

Polyploidy is comparatively prevalent in amphibians and fishes, but is infrequent in animals because of lethality after implantation. On the contrary, tetraploid embryos normally develop into blastocysts, and embryonic stem cells can be established from tetraploid blastocysts in mice. Thus, polyploidization does not seem to be so harmful during preimplantation development. However, the mechanisms by which early mammalian development accepts polyploidization are still poorly understood. In this study, we aimed to elucidate the effect of polyploidization on early mammalian development and to further comprehend its tolerability using hyperpolyploid embryos produced by artificial, repetitive whole genome duplication. Therefore, we successfully established several types of polyploid embryos (tetraploid, octaploid, and hexadecaploid), produced using repeated electrofusion of two-cell embryos in mice, and studied their developmental potential in vitro. We demonstrated that all types of these polyploid embryos maintained the ability to develop to the blastocyst stage, which implies that mammalian cells might have basic cellular functions in implanted embryos, despite polyploidization. However, the inner cell mass was absent in the hexadecaploid blastocysts. To complement the total cells in blastocysts, a fused hexadecaploid embryo was produced by aggregating a number of hexadecaploid embryos. The results indicated that the fused hexadecaploid embryo finally recovered pluripotent cells in blastocysts. Thus, our findings suggested that early mammalian embryos may have the tolerability and higher plasticity to adapt to hyperpolyploidization for blastocyst formation, despite intense alteration of the genome volume.

developmental biology↗