A multicellular star-shaped actin network underpins epithelial organization and connectivity

Epithelial tissues withstand external stresses while maintaining structural stability. Bicellular junctions and the actomyosin network support epithelial integrity, packing and remodelling. While their role in development and disease are well studied, their synergistic impact on maintaining tissue organization remains unclear. Here, we identify a tissue-scale actomyosin network in adult murine intestinal villi, as well as in an ex vivo organoid-based epithelium model. This actomyosin network consists of repeated units of actin stars - radial actin structures at the base of hexagonal cells - linked via bicellular junctions into a multicellular array. Functionally, actin stars maintain epithelial morphological stability by preserving cell shape and packing. Laser ablation experiments support a modified vertex model, linking tension along actin star branches to epithelial arrangement. Additionally, actin stars act as basal locks, limiting protrusive activity, and hindering cell migration and tissue disruption. Together, these findings reveal the star-shaped supracellular actin network as a pivotal biomechanical system governing epithelial layer coordination.