Karpov, K. I. | Search bioRxiv

bioRxiv2026

Mechanical opening of the αE-catenin M-region gates afadin condensation in cardiomyocytes

In mechanically active tissues, cell-cell adhesions must withstand high and dynamic loads to maintain tissue integrity. The ability to detect and withstand load centers on the mechanosensitive adherens junction (AJ), which couples the actin networks of adjacent cells. The mechanosensor E-catenin responds to force by opening its Middle (M) region, revealing cryptic binding sites for adaptor proteins such as afadin and vinculin. Here we show that the afadin coiled-coil (CC) region binds the open E-catenin M-region with modest affinity and fast exchange, unlike the high-affinity, long-lived binding of vinculin, suggesting distinct roles. In cardiomyocytes, the afadin CC is necessary and sufficient for afadin localization at high-load AJs, where it exhibits the dynamic, hexanediol-sensitive properties of a biomolecular condensate. By contrast, the afadin CC is dispensable for recruitment at low-load epithelial AJs, suggesting that junctional load determines the basis of afadin recruitment. We propose that force-gated opening of E-catenin seeds afadin condensate formation, a mechanism that drives reorganization of high-load AJs.

cell biology↗

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↗