Abstract
Cellular sorting and pattern formation are crucial for many biological processes such as development, tissue regeneration, and cancer progression. Prominent physical driving forces for cellular sorting are differential adhesion and contractility. Here, we studied the segregation of epithelial co-cultures containing highly contractile, ZO1/2-depleted MDCKII cells (dKD) and their wildtype (WT) counterparts using multiple quantitative, high-throughput methods to monitor their dynamical and mechanical properties. We observe a time-dependent segregation process, governed mainly by differential contractility on short (< 5 h) and differential adhesion on long (> 5 h) time scales, respectively. The overly contractile dKD cells exert strong lateral forces on their WT neighbors, thereby apically depleting their surface area. This is reflected in a six-fold difference in excess surface area between both cell types. The lateral forces lead to a four-to sixfold increase in tension at all junctions that are in contact with the contractile cells including the interface between heterotypic cell-cell contacts. Concomitantly, the tight junction-depleted, contractile cells exhibit weaker cell-cell adhesion and lower traction force. Drug-induced contractility reduction and partial calcium depletion delay the initial segregation but cease to change the final demixed state, rendering differential adhesion the dominant segregation force at longer time scales.
This well-controlled model system shows how cell sorting is accomplished through a complex interplay between differential adhesion and contractility and can be explained largely by generic physical driving forces.
Significance Statement Fundamental biological processes, such as tissue morphogenesis during development, rely on the correct sorting of cells. Cellular sorting is governed by basic physical properties such as the adhesion between cells and their individual contractility. Here, we study the impact of these parameters in co-cultures consisting of epithelial wildtype cells and overly contractile, less adhesive tight junction-depleted ones. We find time-dependent segregation into clusters: differential contractility drives fast segregation on short-time scales, while differential adhesion dominates the final segregated state over longer times.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Competing Interest Statement: There is no competing interest to declare.
The (minor) role of proliferation in the segregation was examined by proliferation inhibition via mitomycin C. Additional data confirming the main conclusions were added: (de-) mixing experiments upon calcium withdrawal, new adhesion measurements upon ROCK inhibition, and AFM curves with different indentation depths. Additional analyses were added to clarify and support the original results.
