Spatial heterogeneity in epithelial cell area under induced cell contraction

Epithelial tissues are active, dynamic materials that can alter their physical properties in response to external stimuli. The physical mechanisms used to maintain epithelial monolayer integrity during external perturbations are not fully understood. Recent studies have shown that upon elevated cell contractility or under large deformations, epithelial tissues accommodate the resulting deformations through heterogeneities in cell area within the monolayer. We show that by exogenously increasing cell contractility across a cell monolayer, the monolayer divides into regions with small and large cell areas. We track the formation of small and large cells in the monolayer by tracking single cell area, enabled through cell nuclei imaging and Voronoi tessellation. The small and large cells are characterized by comparing cytoskeletal structure and force production, measured through traction force microscopy. The smaller cells express more apical and basal actin, and exert greater cell-substrate traction than the larger cells. Interestingly, this observation is in contrast with prior studies, which showed that larger cells tend to exert greater traction. We hypothesize that the spatial heterogeneity in cell area is a potential mechanism for preserving monolayer integrity.