PhD thesis: Stabilization and motility mechanism of blebs in cancer cells

Blebs are cellular protrusions driven by intracellular pressure that typically retract within minutes after formation. It was recently reported that confined cells migrate by forming a single large stable bleb with fast cortical flows, by upregulating cortical contractility. Here, we report a new type of stable bleb protrusions that appears before cell-scale polarisation. Remarkably, stable blebs bear cortical flows and can self-fragment and migrate autonomously, constituting a simple system to study actomyosin-based motility. We propose a model for bleb morphogenesis in which the final phenotype — transient versus stable bleb — is due to the relative timing of cortex formation versus myosin contraction. Stress percolation and a sol-gel phase transition of the actin network at the leading edge determines bleb stability and shape. The description of a live cellular process explained by percolation theory at a molecular level constitutes a novel contribution to the cytoskeleton field. In this archive, we included raw images, datasets, the original PhD thesis manuscript, and associated Supplementary videos.