Biology subjects

Lee, G.-H.

Publications and source records attributed to Lee, G.-H..

4 recordsLinked to original sources

bioRxiv2025

Neural dynamics of emergent social roles in collective foraging by mice

We investigated how neural dynamics support role differentiation in group foraging by mice cohabiting with a predator-like spider robot serving as a mobile food platform. While solitary foraging behaviors were consistent among mice, group foraging revealed distinct roles-working, participating, and freeriding-that solidified over time, leading to an imbalance (Gini = 0.5) across five groups. Recordings from the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), and basolateral amygdala (BLA) revealed enhanced beta power in active foragers. Workers exhibited a stronger fast beta drive from mPFC to BLA compared to participants, and role prediction accuracy based on spectral features improved over trials. Our findings highlight how neural dynamics underlie the emergence of distinct roles in collective action by mice. One-Sentence SummaryDistinct foraging roles emerge in group-housed mice, driven by fast beta (24-32 Hz) activity in the mPFC-NAc-BLA circuit.

animal behavior and cognition↗

bioRxiv2023

Depletion of tropomyosin 1.6 promotes matrix-degrading phenotype in TGF-β1-induced myofibroblast

Fibroblasts can be transformed into myofibroblasts under pro-fibrotic conditions, which is characterized by increased contractility and reduced matrix degradation. The relationship between contractile activity and matrix degradation is not fully understood. We found that TGF-{beta}1-induced myofibroblast activation occurs on a culture dish, favoring stress fiber formation and inhibiting podosome structures due to high matrix stiffness. To mimic physiological conditions, we cultured fibroblasts on collagen gel. Blocking actomyosin signaling significantly reduced TGF-{beta}1-induced myofibroblast activation. Tpm1.6, an actomyosin-associated contractile unit, was specifically upregulated by TGF-{beta}1 on soft collagen substrates. Depletion of Tpm1.6 attenuated TGF-{beta}1-induced increase of -SMA, N-cadherin, and {beta}1-integrin, indicating its crucial role in early myofibroblast activation during fibrosis progression. Tpm1.6 depletion reduced TGF-{beta}1-induced cell contractility and enhanced collagen degradation. Notably, in Tpm1.6-depleted fibroblasts, TGF-{beta}1 triggered formation of distinct -SMA dot structures enriched with MMP9, promoting collagen degradation. Our study highlights the pivotal role of Tpm1.6 in TGF-{beta}1-induced myofibroblast activation and collagen degradation. Depletion of Tpm1.6 triggers robust collagen degradation through distinct -SMA dots, presenting a potential therapeutic approach for chronic kidney disease.

cell biology↗

bioRxiv2021

Visualization of reactive astrocytes in living brain of Alzheimer's disease patient

An early appearance of reactive astrocytes is a hallmark of Alzheimers disease (AD)1,2, providing a substrate for early diagnostic neuroimaging targets. However, there is no clinically validated neuroimaging probe to visualize the reactive astrogliosis in the human brain in vivo. Here, we report that PET/CT imaging with 11C-acetate and 18F-fluorodeoxyglucose (18F-FDG) functionally visualizes the reactive astrocyte-mediated neuronal hypometabolism in the brains with neuroinflammation and AD. We demonstrate that reactive astrocytes excessively absorb acetate through elevated monocarboxylate transporter-1 (MCT1), leading to aberrant GABA synthesis and release which suppresses neuronal glucose uptake through decreased glucose transporter-3 (GLUT3) in both animal and human brains. We propose the non-invasive functional PET/CT imaging for astrocytic acetate-hypermetabolism and neuronal glucose-hypometabolism as an advanced diagnostic strategy for early stages of AD.

neuroscience↗

bioRxiv2019

Measurements of 3-D morphology of individual red blood cells upon localized photothermal effects using gold nanorods

We investigated the in-situ photothermal response of human red blood cells (RBCs) by combining photothermal heat generation and 3D quantitative phase imaging techniques. Gold-nanorod-coated substrates were excited using near-infrared light to generate local heat to RBCs, and response was measured by imaging 3-D refractive index tomograms of cells under various near infrared (NIR) excitation conditions. On photothermal treatment, cell morphology changed from discoid to crescent shapes, cell volume and dry mass decreased, and hemoglobin concentration increased. We also investigated the irreversible deformation of RBCs when multiple intense excitation shocks are applied. These results provide a new understanding of thermodynamic aspects of cell biology and hematology. O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

biophysics↗