Interplay between membrane protrusive activities and their adhesion strength regulates cell migration

Migratory cells can adopt membrane protrusions like blebbing or lamellipodia for efficient migration. The underlying mechanisms of how switching contributes to cell migration are not clearly understood. Here, we found that nonmuscle myosin II (NM II) mediated blebbing to lamellipodia conversion (BLC) increased the speed of migration, whereas lamellipodia to blebbing conversion (LBC) decreased it in various cells, such as cancerous cells, mesenchymal stem cells, and T-lymphocytes. Cells with lamellipodia had larger and greater numbers of focal adhesions compared with blebbing cells, suggesting a link between adhesion strength and membrane protrusions and migration. Migratory cells seeded on collagen I, but not on poly-L-lysine, exhibited a faster BLC and greater migration speed compared with cells seeded on an uncoated surface. Knockdown of integrinβ1 reduced cell migration, but these cells were able to undergo conversion of membrane protrusions, albeit with a substantial delay. These findings suggest that cells can fine-tune the migration strategy by controlling NM II-mediated protrusion switching and modulating integrin-dependent adhesion strength.