Biology subjects

Lim, D.-S.

Publications and source records attributed to Lim, D.-S..

3 recordsLinked to original sources

bioRxiv2025

De Novo design of a potent Wnt Surrogate specific for the frizzled7 subtype members

In humans, 19 Wnt ligands interact with 10 Frizzled (Fzd) receptors and the co-receptors LRP5/6 to initiate signaling. Wnts and Fzds are highly promiscuous, making it challenging to dissect the specific outcomes of individual Wnt-Fzd interactions. Developing Wnt surrogates with specificity for individual Fzd subtypes could be pivotal. We present a modular, potent, and Fzd7-specific Wnt surrogate that consists of three de novo designed modules, a Fzd7 binder, an LRP6 binder and a homodimeric protein. The Fzd7-specific module was designed by targeting two less conserved surface patches on the cysteine-rich domain (CRD) of Fzds to achieve both selectivity and affinity. It exhibits a strong binding affinity (KD < 2.3 nM) for the very closely related Fzd7 subtype members (Fzd7, Fzd1, Fzd2) with no measurable binding to the CRDs of the other seven Fzd receptors. This Wnt surrogate induced spheroid organoid formation from intestinal stem cells at subnanomolar concentration, and promoted full hair follicle regeneration and robust hair growth in mice. These results suggest that our strategy could be extended to design modular Wnt surrogates capable of selectively activating individual Fzd receptors, providing a valuable tool kit for development and differentiation, organoid cultures and targeted regeneration.

bioengineering↗

bioRxiv2024

Decorin promotes cardiac organoid maturation by activating AMPK-PGC1A pathway to enhance cardiac metabolism and mitophagy

RationaleCardiac organoids (COs) are advanced models for investigating heart development and disease, while require maturation to resemble the structural and functional characteristics of the human heart. ObjectiveThis study reveals the role of Decorin (DCN) contributes to the mature and vascularized COs and assesses the biological mechanism responsible for CO maturation. Methods and ResultsDCN-treated COs exhibit structural maturation involving aligned sarcomere, mitochondria, and t-tubule structures, and vessel formations, as well as functional maturation involving synchronized contraction-relaxation, Ca2+ transient, and increases ion channel expressions. DCN-treated COs also show metabolic maturation, including enhanced fatty acid oxidation and increased mitophagy. Transcriptional profiling results indicate that DCN-treated COs have increased levels of AMPK signaling and mitophagy. In DCN-treated COs, AMPK knockdown affects mitochondrial biogenesis, cardiac metabolism, ion channels, and mitophagy. ConclusionsThese findings indicate that DCN is crucial for development of mature, vascularized COs and that CO maturation is primarily regulated through AMPK signaling, which is triggered by DCN. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/599970v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1333cfaorg.highwire.dtl.DTLVardef@e842baorg.highwire.dtl.DTLVardef@74ce1corg.highwire.dtl.DTLVardef@87ad38_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGRAPHIC ABSTRACTC_FLOATNO A graphic abstract is available for this article. DCN enhances metabolic maturation in COs by AMPK-triggered regulation of the glycolysis, fatty acid oxidation, and mitophagy. C_FIG

developmental biology↗

bioRxiv2024

Formation of a giant unilocular vacuole via macropinocytosis-like process confers anoikis resistance

Cell survival in metazoans depends on cell attachment to the extracellular matrix (ECM) or to neighboring cells. Loss of such attachment triggers a type of programmed cell death known as anoikis, the acquisition of resistance to which is a key step in cancer development. The mechanisms underlying anoikis resistance remain unclear, however. The intracellular F-actin cytoskeleton plays a key role in sensing the loss of cell-ECM attachment, but how its disruption affects cell fate during such stress is not well understood. Here, we reveal a cell survival strategy characterized by the formation of a giant unilocular vacuole (GUVac) in the cytoplasm of the cells whose actin cytoskeleton is disrupted during loss of matrix attachment. Time-lapse imaging and electron microscopy showed that large vacuoles with a diameter of >500 nm accumulated early after inhibition of actin polymerization in cells in suspension culture, and that these vacuoles subsequently coalesced to form a GUVac. GUVac formation was found to result from a variation of a macropinocytosis-like process, characterized by the presence of inwardly curved membrane invaginations. This phenomenon relies on both F-actin depolymerization and the recruitment of septin proteins for micron-sized plasma membrane invagination. The vacuole fusion step during GUVac formation requires PI(3)P produced by VPS34 and PI3K-C2 on the surface of vacuoles. Furthermore, its induction after loss of matrix attachment conferred anoikis resistance. Our results thus show that the formation of a previously unrecognized organelle promotes cell survival in the face of altered actin and matrix environments.

cell biology↗