Epithelial cells cultured in a monolayer are very motile in isolation but reach a near-jammed state when mitotic division increases their number above a critical threshold. We have recently shown that a monolayer can be reawakened by over-expression of a single protein, RAB5A, a master regulator of endocytosis. This reawakening of motility was explained in term of a flocking transition that promotes the emergence of a large-scale collective migratory pattern. Here we focus on the impact of this reawakening on the structural properties of the monolayer. We find that the unjammed monolayer is characterised by a fluidisation at the single cell level and by enhanced non-equilibrium large-scale number fluctuations at a larger length scale. Also with the help of numerical simulations, we trace back the origin of these fluctuations to the self-propelled active nature of the constituents and to the existence of a local alignment mechanism, leading to the spontaneous breaking of the orientational symmetry.
- active matter
- jamming transition
- collective cell migration
- non-equilibrium fluctuations
Giavazzi, F., Malinverno, C., Corallino, S., Ginelli, F., Scita, G., & Cerbino, R. (2017). Giant fluctuations and structural effects in a flocking epithelium. Journal of Physics D: Applied Physics, 50, 1-11. . https://doi.org/10.1088/1361-6463/aa7f8e