Amoeboid Cells Migrate by Alternating Between Modes with Distinct Adhesion Dynamics and Contractility

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Directional cell migration is involved in a broad range of biological phenomena, ranging from the metastatic spreading of cancer to wound healing. Chemotaxing Dictyostelium cells adapt their morphology and speed to external conditions like the stiffness and adhesive properties of their substrate. The mechanism by which they control both their shape and speed remains largely unknown. Using Traction Force Microscopy measurements, we construct traction tension kymographs to examine the spatio-temporal dynamics of both the adhesions and the traction stresses during migration. We show that wild-type cells control their motility by switching between two motility modes with distinct adhesion and contractility dynamics. In the “Stepping-Stepping” mode, the adhesion sites remain stationary while the cell moves forward by periodic axial contractions. The back adhesions break after new frontal adhesions are formed. In the “Stepping-Gliding” mode, the cell reduces the magnitude of the traction stresses, increases the frequency of axial contractions and its migration speed, and keeps the frontal adhesion stationary while sliding the back adhesion forward. These two modes are not conserved when cells move on adhesive poly-L-Lys coated substrates, where cells alternate between a “Nearly Stationary” mode, characterized by strong lateral contractions and extremely low migration speed and a “Gliding-Gliding” mode, where multiple weak and transient adhesions are formed which are gliding forward as the cell moves by barely adhering to the substrate. In summary, our findings have contributed to a more precise understanding of how the coordination of traction stresses together with the adhesion dynamics result in efficient amoeboid cell migration. We propose that these are highly conserved mechanisms, which function in a range of amoeboid cells, including leukocytes, as well as other forms of cell motility.