Moving without motors: Amoeboid cell migration and shape dynamics driven by actin polymerization - Winfried Schmidt (ECCEL, LIPhy)

Mammalian cell motility is essential for many physiological and pathological processes, such as embryonic development, wound healing, and cancer metastasis. Cells have developed the amoeboid migration mode, which is characterized by large, dynamic shape deformations. This strategy allows cells to move rapidly and in the absence of strong adhesion across a variety of different environments, including two-dimensional confinement, three-dimensional matrix, and bulk fluids. Molecular motors, such as myosin, are traditionally considered essential for cell polarization. Here, a model of an amoeboid cell is analyzed both analytically and numerically. It is shown that actin polymerization alone is sufficient to trigger both cell polarity and motility, in line with recent experiments on T-lymphocytes showing that inhibition of molecular motors does not significantly affect motility. Depending on parameter values, the cells exhibit straight, circular, or even chaotic trajectories. A similar variety of motion is observed across multiple motile cells. These findings open up a new perspective on amoeboid motility, providing a scenario for the onset of polarity, migration, and dynamical cell shape changes without contractile activity.