Regulation of Cell-Surface Adhesion During Amoeboid Migration

Abstract

During amoeboid migration, cell-substrate interactions play a critical role by supplying the traction allowing a cell to move itself forward. It has been shown that the ability of individual mammalian cells to move will depend on their adhesiveness to that surface, with moderately adhesive surfaces being ideal: moderate adhesion allows cells to gain traction to move forward while still permitting detachment of the cell rear. In addition to cell-substrate adhesion, migrating cells often experience cell-cell adhesion, and in many systems (such as wound healing or embryogenesis) such adhesion can dominate. The amoeba Dictyostelium discoideum naturally exhibits both cell-substrate and cell-cell adhesion during the aggregation process. We used both high- and low-magnification time-lapse microscopy to investigate the individual and collective migration of D. discoideum on substrates of varying adhesiveness, as well as on interfaces between substrates. We find that non-ideal adhesive surfaces can affect both individual cell migration as well as the behavior of cell groups. At the population scale, non-ideal surfaces slow down the initiation of aggregation and change how the process is performed: instead of forming large aggregation centers, the population forms small aggregation centers which coarsen over time until the standard aggregation center size is eventually reached. At the scale of single cells, we measure both adhesion ability as well as the area of contact between cells and surface for individual cells and cells that are part of groups. On all surfaces the contact area oscillates, reflecting the migration dynamics. Surprisingly, comparable forces are needed to rip cells off all surfaces, indicating that surface adhesion may be regulated by the cells.