Dynamics of cell rounding during detachment.

Animal cells undergo repeated shape changes, for example by rounding up and respreading as they divide. Cell rounding can be also observed in interphase cells, for example when cancer cells switch from a mesenchymal to an ameboid mode of cell migration. Nevertheless, it remains unclear how interphase cells round up. In this article, we demonstrate that a partial loss of substrate adhesion triggers actomyosin-dependent cortical remodeling and ERM activation, which facilitates further adhesion loss causing cells to round. Although the path of rounding in this case superficially resembles mitotic rounding in involving ERM phosphorylation, retraction fiber formation, and cortical remodeling downstream of ROCK, it does not require Ect2. This work provides insights into the way partial loss of adhesion actives cortical remodeling to drive cell detachment from the substrate. This is important to consider when studying the mechanics of cells in suspension, for example using methods like real-time deformability cytometry (RT-DC).