LAUSR

Epithelial monolayers are a classic system of active matter, in which the component particles (cells) endogenously generate forces and change their own shapes without external stimuli. The mechanics of single cells and circular colonies of keratinocytes can be successfully described using a continuum model, however, it is not known how general this model is. Using micropatterning to constrain colonies of MDCK cells to reproducible geometries, the relationship between the shapes of individual cells within the colonies and the mechanical output of otherwise similar colonies can be assessed. We find that wild-type cells are motile with respect to the colony borders and distribute traction forces to localized hot spots that move over time, thus breaking from the continuum model. ZO-1/ZO-2 knockdown cells, which display elevated contractility and straighter cell-cell borders, are employed to examine the impact of these parameters on the magnitude and localization of traction forces.