Biology subjects

Akiyoshi, K.

Publications and source records attributed to Akiyoshi, K..

5 recordsLinked to original sources

bioRxiv2026

In vivo brain temperature measurement using quantum dot imaging temperature sensors

Temperature regulation in the brain is essential for maintaining neuronal function and preventing thermally induced damage. Here, we report the development and in vivo application of quantum dots (QDs) to high-resolution thermometry in the mouse brain using two-photon excitation microscopy. These QDs, via the red-to-green photoluminescence (PL) intensity ratios, enabled stable temperature measurements in both normal and chronically hypo-perfused cerebral tissue. Our findings show that localized neuronal activity leads to transient heat generation, which is rapidly dissipated by cerebrovascular responses. In a chronic hypoperfusion model, impaired vascular function resulted in exaggerated and prolonged brain temperature elevations. This thermometry system provides unprecedented insight into the mechanisms of cerebral thermoregulation and highlights the importance of vascular cooling in protecting the brain from heat-induced stress, particularly in pathological conditions such as stroke.

bioengineering↗

bioRxiv2023

A Straightforward Approach for Living Biomembrane Printing onto Nanoparticle

Biomembrane coating technologies have increasingly been pursued to grant natural dynamic bio-interfaces onto synthetic nanomaterials. Herein, we report a one-step method to coat "living" biomembrane on nanoparticle surfaces in a non-destructive manner. In our method, nanoparticles were efficiently coated with cell membranes without losing the structural integrity by mechanically facilitating the passage of nanoparticles to a concentration layer of living cells with simple centrifugation. This was similar to the exosome-releasing process via endocytosis and exocytosis. The biomembrane originating from living Raw264.7 cells was coated onto the silica nanoparticle prepared by our method, and proteome profiling with nanoflow liquid chromatography-tandem mass spectrometry demonstrated that it was constructed with proteins derived from the membranous component. This proteome profile was not observed in silica nanoparticles prepared with dead cells. Finally, the hybridized cell membrane effectively suppressed the phagocytic activity of Raw264.7 cells to silica nanoparticles and improved the uptake efficiency into cancer cells. We believe our simple and efficient method to coat living biomembranes should be useful in developing medical and pharmaceutical applications involving nanoparticles.

synthetic biology↗

bioRxiv2022

Classification of Extracellular Vesicles based on Surface Glycan Structures by Spongy-like Separation Media

Extracellular vesicles (EVs) are lipid bilayer vesicles that enclose various biomolecules. EVs hold promise as sensitive biomarkers to detect and monitor various diseases. However, they have heterogenous molecular compositions. The compositions of EVs from identical donor cells obtained using the same purification methods may differ, which is a significant obstacle for elucidating objective biological functions. Herein the potential of a novel lectin-based affinity chromatography (LAC) method to classify EVs based on their glycan structures is demonstrated. The proposed method utilizes a spongy-like monolithic polymer (spongy monolith, SPM), which consists of poly(ethylene-co-glycidyl methacrylate) with continuous micropores and allows an efficient in-situ protein reaction with epoxy groups. Two distinct lectins with different specificities, Sambucus sieboldiana agglutinin and concanavalin A, are effectively immobilized on SPM without impacting the binding activity. Moreover, high recovery rates of liposomal nanoparticles as a model of EVs are achieved due to the large flow-through pores (>10 m) of SPM. Finally, lectin-immobilized SPMs are employed to classify EVs based on the surface glycan structures and demonstrate different subpopulations by proteome profiling.

biochemistry↗

bioRxiv2021

Role of miR-181c in Diet-Induced Obesity Through Regulation of Lipid Synthesis in Liver

We recently identified a nuclear-encoded miRNA (miR-181c) in cardiomyocytes that can translocate into mitochondria to regulate mitochondrial gene (mt-COX1), and influence obesity-induced cardiac dysfunction through mitochondrial pathway. Liver plays a pivotal role during obesity. Therefore, we hypothesized that miR-181c plays an important role in pathophysiological complications associated with obesity. We used miR-181c/d-/- mice to study the miR-181c role in lipogenesis in hepatocytes during diet-induced obesity (DIO). Indirect calorimetric measurements were made during the 26 weeks high fat diet (HFD) exposure. qPCR was performed to examine the gene expression involved in lipid synthesis. Here, we show that miR-181c/d-/- mice are not protected against all metabolic consequences of HFD exposure. After 26 weeks of the HFD, miR-181c/d-/- mice had a significantly higher body fat (%) compared to WT. Glucose tolerance tests showed hyperinsulinemia and hyperglycemia, indicative of insulin insensitivity in the miR-181c/d-/- mice. HFD-fed miR-181c/d-/- mice had higher serum and liver triglyceride levels compared to HFD-fed WT mice. qPCR data demonstrated that several genes which are regulated by isocitrate dehydrogenase 1 (IDH1) were upregulated in miR-181c/d-/- liver compared to WT liver. Furthermore, an AAV-8 was used to deliver miR-181c, in vivo, to validate the potential role of miR-181c in the liver. miR-181c delivery attenuate the lipogenesis by downregulating the same lipid synthesis genes in the liver. In hepatocytes, miR-181c regulates lipid biosynthesis by targeting IDH1. Taken together, the data indicate that overexpression of miR-181c can be beneficial for various lipid metabolism disorders.

cell biology↗

bioRxiv2020

New Lipophilic Fluorescent Dyes for Exosome Labeling: Monitoring of Cellular Uptake of Exosomes

We have developed three types of exosomal membrane binding fluorescent probes, Mem Dye-Green, Mem Dye-Red and Mem Dye-Deep Red, to monitor exosome uptake into cells. The dyes contain a cyanine group as a fluorescent scaffold, which allows for highly sensitive fluorescence imaging of the exosome. These dyes can also be used to observe the dynamics of exosomes in live cells. The use of PKH dyes (Figure 1), which are currently the most widely-used fluorescent probes for exosome labeling, has some limitations. For example, PKH dyes tend to aggregate to form exosome-like nanoparticles, and these nanoparticles are uptaken by cells. Moreover, Mehdi suggested that the use of PKH dyes triggers an enlargement of the exosome size owing to membrane fusion or intercalation. To overcome the limitations of PKH dyes, we introduce amphiphilic moieties to the cyanine. To investigate the characteristics of the Mem Dyes as exosome labeling probes, we perform nanoparticle tracking analysis (NTA), zeta potential measurement and confocal microscopy. The Mem Dyes show excellent performance for exosome labeling (no aggregation and less size shift). O_FIG O_LINKSMALLFIG WIDTH=91 HEIGHT=200 SRC="FIGDIR/small/931295v1_fig1.gif" ALT="Figure 1"> View larger version (8K): org.highwire.dtl.DTLVardef@e978aeorg.highwire.dtl.DTLVardef@1f208cdorg.highwire.dtl.DTLVardef@11fdb1dorg.highwire.dtl.DTLVardef@6a7373_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Chemical structure of PKH26. C_FIG

biochemistry↗