A single stiffened nucleus alters cell dynamics and coherence in a monolayer.

Force transmission throughout a monolayer is the result of complex interactions between cells. Monolayer adaptation to force imbalances such as singular stiffened cells provides insight into the initiation of disease and fibrosis. Here, NRK-52E cells transfected with ∆50LA, which significantly stiffens the nucleus. These stiffened cells were sparsely placed in a monolayer of normal NRK-52E cells. Through morphometric analysis and temporal tracking, the impact of the singular stiffened cells shows a pivotal role in mechanoresponse of the monolayer. A method for a detailed analysis of the spatial aspect and temporal progression of the nuclear boundary was developed and used to achieve a full description of the phenotype and dynamics of the monolayers under study. Our findings reveal that cells are highly sensitive to the presence of mechanically impaired neighbors, leading to generalized loss of coordination in collective cell migration, but without seemingly affecting the potential for nuclear lamina fluctuations of neighboring cells. Reduced translocation in neighboring cells appears to be compensated by an increase in nuclear rotation and dynamic variation of shape, suggesting a "frustration" of cells and maintenance of motor activity. Interestingly, some characteristics of the behavior of these cells appear to be dependent on the distance to a ∆50LA cell, pointing to compensatory behavior in response to force transmission imbalances in a monolayer. These insights may suggest the long-range impacts of single cell defects related to tissue dysfunction.