A supracellular actin network transmits forces over long distances at the apical surface of squamous carcinoma cells

Epithelial tissues form protective barriers while supporting crucial functions, such as absorption and secretion. Their structural and functional integrity relies on adherens junctions, which coordinate migration and transmit forces between adjacent cells by connecting their actin Cytoskeleton. In this study, we report the presence of an apical supracellular actin network in squamous epithelial cells. Using squamous carcinoma A431 cells as a model, we characterized this network composed of star-shaped actin structures interconnected by linear actin bundles that span multiple cells. We demonstrate that the formation and maintenance of the network require actomyosin contractility and intact adherens junctions, whereas tight junctions seem dispensable. Furthermore, this network dynamically reorganizes as cells migrate and preferentially aligns with the direction of movement. This contractile structure generates mechanical tension that extends across the apical surface of multiple cells. Our findings suggest that this supracellular actin network functions as a long-range force transmission device in squamous cells, advancing our understanding of the biomechanical properties of epithelia.

Actin; Adherens junctions; Collective cell migration; Force transmission; Squamous cells; Supracellular actin structure; Tension.