Zyxin and non-muscle myosin are required for single fibroblast durotaxis, but Rho-kinase activity and the Arp2/3 complex are dispensable

Abstract

Durotaxis, migration of cells directed by stiffness gradient, is critical in development and disease. To study the molecular determinants of single cell durotaxis, we developed an all-in-one photopolymerized hydrogel system containing areas of stiffness gradients with different slopes, along with uniform stiffness (soft and stiff) regions. We find that fibroblasts rely on non-muscle myosin II (NMII) activity and the LIM-domain protein zyxin for durotaxis on both steep and shallow stiffness gradients. Importantly, unlike haptotaxis, the Arp2/3 complex is dispensable for durotaxis on both stiffness gradients. Lack of Arp2/3 results in a filopodia-based durotactic migration that is equally efficient as that of lamellipodia-based durotactic migration. Finally, we reveal an essential role for the actin-bundler fascin in the formation and asymmetric distribution of filopodia during filopodia-based durotaxis in shallow, but not steep, stiffness gradient. Together, our all-in-one hydrogel system can serve as a platform to identify, discriminate, and characterize stiffness gradient specific molecular mechanisms that cells employ to efficiently durotax.