Exact mechanisms of epithelial cell extrusion

Determine the exact biophysical mechanisms of epithelial cell extrusion in epithelial tissues, including quantifying the contributions of specialized actin structures on the lateral and basal cell surfaces, to clarify how dying cells are expelled while maintaining the epithelial barrier.

Background

Epithelial tissues regulate cell density through a balance of cell division and cell extrusion, ensuring removal of dying cells without compromising barrier integrity. While extrusion is well documented and associated with actin-driven processes, the precise mechanistic pathway remains unresolved.

This paper develops a three-dimensional bubbly vertex model to study how curvature and topological defects promote bulging and extrusion, offering theoretical insights and predictions. However, the foundational question of the exact molecular and mechanical pathways driving extrusion—beyond identifying candidate actin structures—remains open and is explicitly acknowledged by the authors.