Soleilhac, M.; Ruiz, L.; Berrebi, D.; Barai, A.; Lecouffe, B.; Richelme, S.; Obino, V.; Dang, T.; Buzhinsly, N.; Rico, F.; Salomon, J.; Ruemmele, F.; DELACOUR, D.

Crypt morphogenesis is a fundamental process that drives intestinal growth and maintains its homeostasis. Although intestinal tissue mechanics is recognized as pivotal for early crypt initiation and budding, the molecular mechanisms that couple epithelial forces to mature crypt behavior remain largely unexplored. In particular, while Paneth cells have been proposed to be implicated in the mechanical control of crypt remodeling and fission, the underlying pathways have remained elusive. Here, we identified EpCAM (Epithelial Cell Adhesion Molecule) as a key regulator of epithelial contractility and crypt morphogenesis. EpCAM was preferentially enriched at lateral interfaces of Paneth cells in vivo and in organoid models, where it maintained cortical tension and contractile organization. Loss of EpCAM disrupted crypt cell cortical myosin II-A localization, leading to aberrant Paneth cell apical contractility, enlarged apical surfaces, distorted pyramidal morphology, and altered aspect ratios. Consequently, Paneth cells lose their tight clustering in crypt base, their spatial distribution along the crypt axis becomes irregular, and the collective architecture of the crypt epithelium was compromised. At the tissue level, EpCAM deficiency profoundly perturbed crypt fission, increasing fission frequency while favoring asymmetric outcome both in EPCAM-mutated Congenital Tufting Enteropathy (CTE) patients. Live imaging of EpCAM-knockout mouse organoids confirmed a failure in the spatial control of crypt bifurcation. Collectively, our findings revealed that EpCAM is not required to initiate fission, but is essential to coordinate the mechanical forces and ensure correct division of the crypt. We showed that EpCAM-dependent biomechanical integrity of Paneth cells generates a stabilizing force field at the crypt base, orchestrating coordinated tissue remodeling. Disruption of this program led to unbalanced force transmission, distorted crypt geometry, and aberrant fission outcomes, revealing a critical link between epithelial mechanics and intestinal morphogenesis.