Valentin Laplaud, Nicolas Levernier, Judith Pineau, Mabel San Roman, Lucie Barbier, Pablo J. Sáez, Ana-Maria Lennon-Duménil, Pablo Vargas, Karsten Kruse, Olivia du Roure, Matthieu Piel and Julien Heuvingh
The cell cortex is a contractile actin meshwork, which determines cell shape and is essential for cell mechanics, migration, and division. Because its thickness is below optical resolution, there is a tendency to consider the cortex as a thin uniform two-dimensional layer. Using two mutually attracted magnetic beads, one inside the cell and the other in the extracellular medium, we pinch the cortex of dendritic cells and provide an accurate and time-resolved measure of its thickness. Our observations draw a new picture of the cell cortex as a highly dynamic layer, harboring large fluctuations in its third dimension because of actomyosin contractility. We propose that the cortex dynamics might be responsible for the fast shape-changing capacity of highly contractile cells that use amoeboid-like migration.