Biology subjects

Tran, Y. T. B.

Publications and source records attributed to Tran, Y. T. B..

3 recordsLinked to original sources

bioRxiv2026

N-cadherin orientational order decreases with mechanical load at cardiomyocyte adherens junctions

Adherens junctions physically connect neighboring cells and are built around classical cadherins, homophilic transmembrane proteins that link to the actin cytoskeleton. Classical cadherins can organize into ordered arrays in vitro, but whether they do so in cells remains to be established. Here, we use fluorescence polarization microscopy to show that the classical cadherin N-cadherin is orientationally ordered at cardiomyocyte cell-cell junctions. Whereas the desmosomal cadherin desmoglein 2 was similarly ordered across junction types, N-cadherin order was spatially heterogeneous. Order was lowest where organized myofibrils terminate at high-load, vinculin-enriched axial junctions and highest at low-load, vinculin-poor lateral junctions. This inverse relationship between order and mechanical load suggests that robust cadherin-mediated adhesion does not require ectodomain order. Our findings provide evidence that a classical cadherin is orientationally ordered in cells and show that mechanically active adhesions adopt distinct organizational strategies according to local mechanical demands. Summary StatementAt cardiomyocyte junctions, N-cadherin is ordered where mechanical load is low but disordered where load is high, suggesting that cadherin organization adapts to local force conditions.

cell biology↗

bioRxiv2025

The role of actin dynamics in vesicle formation during clathrin mediated endocytosis

Clathrin-mediated endocytosis (CME) is an important internalization route for macromolecules, lipids, and membrane receptors in eukaryotic cells. During CME, the plasma membrane invaginates and pinches off forming a clathrin coated vesicle. We previously identified heterogeneity in this process with clathrin coated vesicles forming though multiple routes including simultaneous clathrin accumulation and membrane invagination (constant curvature; CCM) as well as membrane bending after accumulation of flat clathrin (flat to curved; FTC). The architectural dynamics of vesicle formation could be influenced by osmotic or confining pressure, membrane stiffness, fluid force, or cytoskeletal arrangement. Whether these biophysical factors regulate the heterogeneity of vesicle formation dynamics is not well understood. To address this, we investigated the interconnected roles of actin and membrane tension in CME using simultaneous two-wavelength axial ratiometry (STAR) microscopy with nanometer-scale axial resolution. First, we treated Cos-7 cells with latrunculin A (LatA) to inhibit actin polymerization and found the total number of clathrin coated vesicles increased significantly, short-lifetime curved events especially. The proportion of vesicles formed following the FTC model was reduced, the membrane curved sooner after clathrin recruitment, and vesicles were less stable in the x-y plane compared to control. Next, we disrupted actin branching by inhibiting Arp2/3 with CK-869. We found an increased delay between membrane invagination and clathrin recruitment, reduced number of curved events, increased vesicle stability and an increase in the FTC model compared to control. As loss of actin filaments also reduces membrane tension, we treated Cos7 with high osmolality to decrease membrane tension and observed similar result with LatA treated group except vesicle stability stayed unchanged. This suggested the increased curved events in LatA groups may result from reduced membrane tension. We conclude actin polymerization promotes FTC while actin branching promotes vesicle formation though the CCM.

cell biology↗

bioRxiv2025

Desmoplakin tail domain position in the desmosomal plaque is isoform dependent

Desmoplakin (DP) is the anchoring subunit of desmosomes, macromolecular junctions that provide mechanical integrity to the skin and heart. DP has three isoforms, DPI, DPIa, and DPII that arise from alternative splicing. The isoforms are structurally identical excluding the length of their central rod domain. As desmosomes are macromolecular complexes, the precise arrangement of their component proteins, or architecture, is essential to maintain physiological function. Alterations of the tissue-specific expression of DP isoforms underlies rare human diseases impacting the skin and heart. Overall DP is oriented with its head domain closest to the plasma membrane and tail domain extending into the cytosol. However, the differences in the architecture of the DP isoforms within the desmosomal plaque remains unknown. Here, we sought to define the architectural arrangement of each DP isoform. To address this, we utilized direct stochastic optical reconstruction microscopy (dSTORM) and analysis of DP KO HaCaT cells stably expressing DPI, DPIa, or DPII with a C-terminal mEGFP tag. Our results show the DP head domain position in the desmosomal plaque is isoform independent and the DP tail domain position correlates with rod length. The tail domain of DPI, the isoform with the longest rod, is furthest from the plasma membrane and that of DPII, the isoform with the shortest rod, is closest. We propose a variable tail location model to describe the architectural arrangement of each isoform. In this model, the DP isoforms are arranged with their rod domains parallel at an angle between 21{degrees} to 25{degrees} from the plasma membrane. These results provide valuable insight into the role of DP isoforms in desmosomal architecture and function.

cell biology↗