Biology subjects

Kuo, C.-J.

Publications and source records attributed to Kuo, C.-J..

3 recordsLinked to original sources

bioRxiv2026

Hormetic heat shock activates HLH-30/TFEB independently of canonical nutrient-sensing pathways

In Caenorhabditis elegans, a brief, sublethal heat shock (HS) induces a hormetic response that increases resistance to subsequent stress and extends lifespan. These benefits require hlh-30, the ortholog of mammalian transcription factor EB (TFEB). Although HS induces robust HLH-30 nuclear translocation, how this response is regulated remains poorly understood. Nutrient- and energy-sensing pathways, including mTORC1 and AMPK, regulate HLH-30/TFEB subcellular localization under other physiological conditions, but whether they mediate its nuclear translocation during HS is unknown. Here, we show that, although HS inhibited mTORC1 and dephosphorylated its conserved HLH-30 S201 target site, HLH-30 S201 phosphorylation was dispensable for HS-induced HLH-30 nuclear localization and hormetic protection. Moreover, HS remained protective in hlh-30 mutants when mTORC1 activity was reduced, revealing an HLH-30-independent component of the hormetic response. HS also activated AMPK and aak-2 was required for hormetic protection but dispensable for HS-induced HLH-30 nuclear localization and autophagosome formation. Together, these findings demonstrate that although HS engages canonical mTORC1 and AMPK signaling, these pathways do not account for HS-induced HLH-30 nuclear localization and instead make distinct contributions to hormetic protection. Our findings reveal stress-specific regulation of HLH-30/TFEB and point to additional mechanisms that drive its activation during heat stress.

cell biology↗

bioRxiv2026

Nanodisc-Mediated Visualization of Crowding-Induced Condensation and Membrane Reorganization in Two-Dimensional Membrane Environments

Although biological membranes exhibit complex and dynamic organization, the mechanistic role of molecular crowding in governing lateral membrane heterogeneity remains poorly characterized experimentally. Here, we provide direct experimental visualization showing that crowding-induced condensation of membrane-anchored macromolecules above the bilayer interface reorganizes membrane dynamics and gives rise to spatially heterogeneous lipid mobility. Both PEGylated lipids and membrane-anchored proteins undergo surface-density-driven condensation on supported lipid bilayers, forming immobile regions that constrain lipid diffusion. Notably, the condensation threshold varies inversely with PEG chain length and surface density, defining a quantitative relationship between molecular size and crowding strength. To directly visualize these crowding-induced structures, we employed nanodelivery using lipid-loaded nanodiscs, revealing a clear correspondence between condensed crowder regions and diffusion barriers reminiscent of the picket-fence model of live-cell membranes. Similar condensation behavior observed for protein-crowded SLBs demonstrates the generality of this crowding-driven mechanism. Together, these findings establish surface-density-driven crowding and condensation of membrane-anchored macromolecules as a key physical mechanism underlying lateral membrane inhomogeneity and position nanodelivery as a general approach for interrogating membrane organization across synthetic and biological systems.

biophysics↗

bioRxiv2021

Plakoglobin and HMGB1 mediate intestinal epithelial cell apoptosis induced by Clostridioides difficile TcdB

Clostridioides difficile infection (CDI) is the leading cause of antibiotic-associated intestinal disease, resulting in severe diarrhea and fatal pseudomembranous colitis. TcdB, one of the essential virulence factors secreted by this bacterium, induces host cell apoptosis through a poorly understood mechanism. Here, we performed an RNAi screen customized to Caco-2 cells, a cell line model of the intestinal epithelium, to discover host factors involved in TcdB-induced apoptosis. We identified plakoglobin, also known as junction plakoglobin (JUP) or {gamma}-catenin, a member of the catenin family, as a novel host factor, and a previously known cell death-related chromatin factor, high mobility group box 1 (HMGB1). Disruption of those host factors by RNAi and CRISPR resulted in resistance of cells to TcdB-mediated and mitochondria-dependent apoptosis. JUP was redistributed from adherens junctions to the mitochondria and colocalized with Bcl-XL after stimulation by TcdB, suggesting a role of JUP in cell death signaling through mitochondria. Treatment with glycyrrhizin, an HMGB1 inhibitor, resulted in significantly increased resistance to TcdB-induced epithelial damage in cultured cells and a mouse ligated colon loop model. These findings demonstrate the critical roles of JUP and HMGB1 in TcdB-induced epithelial cell apoptosis.

microbiology↗