Durotaxis and Frictiotaxis

Durotaxis and Frictiotaxis



Cells migrate along gradients of substrate stiffness — a process called durotaxis. Here, I will show that this process relies on different physical mechanisms that operate in different contexts. First, I will discuss the collective durotaxis of cell clusters on adhesive surfaces. In this case, durotaxis is driven by the active traction forces exerted by cells on the substrate through focal adhesions. Combining theory and experiments, I will show that durotaxis is related to the wetting properties of the cell clusters, which we model as active droplets. This model allows us to explain the experimental observation that durotaxis is optimal at intermediate substrate stiffnesses. Then, I will discuss the durotaxis of single cells in non-adhesive channels, in the absence of focal adhesions. Combining theory and experiments, I will show that the mechanism of this adhesion-independent durotaxis is based on the fact that stiffer substrate offers higher friction. Therefore, cells actually perform frictiotaxis — a new mode of directed cell migration guided by friction gradients. Altogether, these results show that durotaxis is very robust: Cells use different mechanisms to perform it as both collectives and single cells, and on both adhesive and non-adhesive substrates.