Epithelial tissues form protective barriers while supporting critical 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 network's formation and maintenance require actomyosin contractility and intact adherens junctions, while 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.
Marpeaux et al. (Thu,) studied this question.